JP6408297B2 - Beam forming method, measurement imaging apparatus, and communication apparatus - Google Patents

Description

  The present invention relates to a beam forming method for performing beam forming using an arbitrary wave coming from a measurement target. Furthermore, the present invention relates to a measurement imaging apparatus and a communication apparatus that use such a beamforming method.

  In particular, the present invention captures an image of a measurement object based on an electromagnetic wave, light, dynamic vibration, sound wave, or arbitrary wave such as a heat wave coming from the measurement object, or temperature or displacement in the measurement object. The present invention relates to a digital beam forming method in an imaging apparatus for nondestructively measuring the physical quantity, composition, structure, or the like. There are various measurement objects such as organic substances, inorganic substances, solids, liquids, gases, objects that follow rheology, living creatures, astronomical objects, the earth, and the environment, and the application range is extremely wide.

  The present invention can be applied to nondestructive inspection, diagnosis, resource exploration, material and structure generation and manufacturing, various physical and chemical repairs and treatment monitoring, clarified functions and physical properties, etc. Relatedly, in such cases, accuracy may be required under conditions that are not invasive, minimally invasive, noninvasive, and the like, without causing great disturbance to the measurement target. Ideally, the measurement object should be observed in situ in situ.

  In addition, treatment or repair may be performed on the measurement target by the action of the wave itself, and the situation may be observed by performing beam forming on the response from the measurement target at that time. Also, beam forming is performed in satellite communication, radar, sonar, etc. to realize an informationally safe environment under energy saving, and accurate communication is performed. Beam forming has also been applied to ad hoc communication devices and mobile communications. When the measurement target is dynamic, real-time characteristics are required, and beam forming is required to be completed in a short time.

  In a wave such as an electromagnetic wave, light, dynamic vibration, sound wave, or heat wave, the behavior as a wave varies depending on the frequency, bandwidth, intensity, or mode. Many types of transducers of various types of waves have been developed so far, and imaging using transmitted waves, reflected waves, refracted waves, scattered waves (forward scattered waves, back scattered waves, etc.) of these waves has been performed.

  For example, it is well known that ultrasonic waves having a high frequency among sound waves are used in non-destructive inspection, medical care, and sonar. Also in the radar, electromagnetic waves (radio waves, FM waves, microwaves, terahertz waves, infrared rays, visible light, ultraviolet rays, radiation such as X-rays, etc.) having an appropriate frequency according to the measurement object are used. The same applies to other waves, and each wave behaves differently depending on the frequency.Therefore, different sensing and communication are performed according to the measurement object, medium, and frequency band. , Polarization can also be used).

  In those applications, a beam forming process is often performed by mechanically scanning a measurement target with a transducer, using the same transducer multiple times, or using a plurality of transducers arranged in advance in an array. . It is well known that aperture surface synthesis processing is performed when observing the earth, land, ocean, and weather with satellite or airplane radar. Beam forming is often aimed at obtaining a high spatial resolution and a high contrast in a region of interest or a point of interest by providing appropriate directivity particularly when imaging a measurement target.

  As a result, by acting on the wave generated from the measurement object, reflection and transmission, various scattering (Rayleigh scattering, Mie scattering, etc.), attenuation, or frequency dispersion due to spatial changes in impedance are observed. It is possible to observe the structure and composition of the inside and surface of the measurement object based on what the measurement object is. The measurement object may be observed with various spatial resolutions. It can be characterized at the level of structure or composition (eg, individual level, molecular level, atomic level, nuclear level, etc.).

  For the purpose of high-accuracy high-resolution imaging, signal compression techniques have been used for a long time, and chirp wave techniques and coding compression techniques have been used as representative ones. In some cases, such as ISAR (Inverse Synthetic Aperture Radar), the observed wave is subjected to inversion of the beam characteristics to perform super-resolution (not always during aperture synthesis). ), And may actively reduce resolution. Among them, singular value decomposition and regularization are effective.

  In addition, the encoding technique is also used when a plurality of signals are separated, for example, when a received signal is separated into received signals corresponding to transmission signals having different transmission positions. Waves coming from different directions may be separated, and signal sources may be identified and separated. In such a case, the place which relies on the matched filter with high signal detection ability is great. However, while it is possible to acquire signal energy, when obtaining the movement, displacement, distortion, etc. of the measurement object accompanied by deformation, the spatial resolution is lowered, and the measurement accuracy is lowered. In separating waves and signals, it is also useful to use frequencies, bands, or multidimensional spectra.

  In the imaging using the above-described wave, the distribution of amplitude data obtained through orthogonal detection, envelope detection, or square detection is usually displayed as a gray image or a color image in one, two, or three dimensions. Often resulting in a morphological image. Functional observation is also possible. For example, in Doppler measurement using these waves, raw coherent signals are processed (ultrasonic Doppler, radar Doppler, laser Doppler, etc.).

  In addition, for example, in the field of medical ultrasound, there is a useful technique that can detect a moving tissue although there is no information on the displacement direction, as in power Doppler. In addition, when microwaves or far infrared rays are used, the temperature distribution of the measurement target can also be observed. These measured physical quantities may be displayed superimposed on the morphological image. In the field of image measurement, it is well known that motion is observed using a signal made incoherent through detection (cross-correlation processing, optical flow, etc.). In medical ultrasound and sonar, imaging using physically generated harmonics, chords, and difference tones is also performed. In particular, when the measurement target is dynamic, real-time characteristics are required for the beam forming process.

  In satellite communications, radar, sonar, etc., beam forming is performed to realize an informationally safe environment under energy saving, and accurate communication is performed. Beam forming has also been applied to ad hoc communication devices and mobile communications. It is also effective for communication with a specific person, a specific signal generation source, and a specific position. In communication, information may be transmitted from a transmitter to a receiver on a wave, and the purpose may be achieved by itself, or the receiver may return the result of the communication to the transmitter, Of course, there is a case of responding to the request, but of course the example of communication is not limited to this. Real-time characteristics are required when the content of information is dynamic depending on the communication target and observation target, and beam forming in that case is required to be completed in a short time.

  Under such circumstances, the first inventor of the present application (the charcoal good friend, the inventor first described in the application), for example, for differential diagnosis of cancerous lesions, sclerosis and the like in human tissues. Development of ultrasonic imaging technique. The first inventor of the present application performs high resolution and high efficiency of HIFU (High Intensity Focus Ultrasound) treatment as well as high resolution of echo imaging and high precision measurement imaging of tissue displacement. And imaging them based on the reception of echoes during intense ultrasound radiation. Such imaging is based on performing high-speed and appropriate beam forming, and high-speed and appropriate detection methods, tissue displacement measurement methods, shear wave propagation measurement methods, and the like have been reported in the past.

  More than 20 years have passed since the medical ultrasonic diagnostic imaging apparatus was digitized. In older cases, a device that performs mechanical scanning using a single aperture conversion element and then performs electronic scanning using a plurality of conversion elements and an array type device composed of them is an analog device. To digital equipment. In fact, the classic aperture synthesis process itself was digital beamforming from the time it was used in radar mounted on satellites and airplanes, but the received signal strength was weak. For that reason, it was rarely used in medical ultrasound.

  On the other hand, in recent years, the first inventor of the present application has invented a multidirectional aperture plane synthesis method and invented beamforming in multiple directions from received echo data for aperture plane synthesis. As a result, it is possible to obtain a multi-directional steering (deflection) image signal at the same frame rate as that of a normal electronic scan, and by performing coherent addition thereof, lateral modulation imaging (depth direction and It has a horizontal carrier frequency orthogonal to this, and has a higher spatial resolution than normal imaging. Furthermore, by using together the multidimensional autocorrelation method invented by the first inventor of the present application, the displacement vector distribution can be measured in real time. In addition, when incoherent addition is performed, it is also possible to reduce speckles (normally, transmission beams are generated in different directions to reduce speckles, but according to the multidirectional aperture synthesis method, High frame rate). Outside the field of ultrasound, digitization is progressing in sensing devices that use radiation such as microwaves, terahertz waves, X-rays, other electromagnetic waves, vibration waves including sound, and heat waves for nondestructive inspection. It has been.

  For example, aperture synthesis in these sensing devices is active beamforming, and the waves to be processed are transmitted waves, reflected waves, refracted waves, or scattered waves (forward) of those waves generated by the transducer. Scattered waves or backscattered waves). On the other hand, in passive beamforming, for example, the temperature distribution measurement based on the above-mentioned microwave observation and the case of observing the electrical activity source due to the brain magnetic field of living creatures are self-divergent. A transmitted wave, a reflected wave, a refracted wave, or a scattered wave (a forward scattered wave, a back scattered wave, or the like) based on a wave emitted from a (self-emanating) signal source is a target. There are many other examples that correspond to these, but as an example different from them, recently, we have called living organisms as measurement objects, called photoacoustics, irradiating measurement objects with lasers, and frequency-dependent A volume change is caused by a certain heat absorption, an ultrasonic wave is generated using this as a sound source, and peripheral blood vessels are differentiated as a result of beam forming.

  A digital device requires more processing time than an analog device, but its computational processing capability has been greatly improved, and it has been downsized, including data storage media, has become inexpensive, and higher-order calculation processing There are many advantages such as being easy to apply and having a high degree of freedom. In fact, even in digital devices, high-speed analog processing after receiving a signal by a sensor is extremely important in sensing devices, and AD conversion (analogue-to-digital conversion) is relatively close. It can be appropriately realized in combination with the digital processing after.

  In an analog device, transmission and reception beamforming are performed by analog processing. On the other hand, in a digital apparatus, transmission beam forming is performed by analog processing or digital processing, and reception beam forming is performed by digital processing. Therefore, in the present application, the digital beamformer means that the reception beamforming is always performed by digital processing.

  After receiving a wave from a measurement object through a plurality of transducer elements, an array type device composed of them, or mechanical scanning of one or more transducer elements, DAS (Delay and Summation) is a so-called aperture plane synthesis process. Addition) processing is performed. In transmission, transmission beam forming may be performed by driving a plurality of elements, and classical aperture synthesis based on single element transmission may be performed. However, in reception beam forming, , DAS processing is performed.

  That is, transmission beam forming is performed by analog processing or digital processing. On the other hand, in receive beamforming, a received signal is generated by receiving a wave by each element in the array or at a different position, and the analog received signal is output after level adjustment or analog filtering by analog amplification or attenuation. A / D conversion into a digital reception signal is performed, and the digital reception signal is stored in a memory. After that, devices and computers with general-purpose computing power, PLD (Programmable Logic Device), FPGA (Field-Programmable Gate Array), DSP (Digital Signal Processor), Digital processing is performed on the stored received signal using a GPU (Graphical Processing Unit), a microprocessor, or a dedicated computer, a dedicated digital circuit, or a dedicated device. The

  Devices that perform these digital processes may include analog devices, AD converters, memories, and the like. Devices and computers with computing power may be multi-core. As a result, at the time of reception, dynamic focusing, which is almost impossible with an analog device, can be easily performed. Parallel processing is also performed. In order to increase the speed of analog processing and digital processing, a transmission line (for example, a stacked circuit) and a broadband wireless path are important.

  Dynamic focusing improves the spatial resolution in the range direction of the generated image signal and the depth direction (depth direction) of the measurement target. On the other hand, the dynamic focusing of transmission is possible only in the case of classic aperture synthesis by single-element transmission. In order to secure the energy of the transmission wave, transmission beam forming at a fixed focal position by multiple element driving is often performed instead of aperture plane synthesis by single element transmission.

  The first inventor of the present application invented high-frame-rate echo imaging that transmits a wave whose wavefront broadens in the horizontal direction, such as a plane wave, and interrogate a wide range in one transmission. Further, the first inventor of the present application coherently adds (superimposes) a plurality of waves of this kind having different steering (deflection) angles, and performs lateral modulation or widening in the lateral direction (high resolution in the lateral direction). In particular, when the above-described multidimensional autocorrelation method is realized, blood flow in the carotid artery where shear wave propagation or blood flow is fast, or in the heart chamber where complicated flow occurs Invented measuring blood flow etc. as a multidimensional displacement vector. The same applies when multidirectional aperture synthesis is performed and when transmission beamforming is performed. In addition, a plurality of waves having different carrier frequencies may be generated and overlapped to realize a wide band in the axial direction (high resolution in the axial direction).

  Such processing is performed in the case of active beam forming, but a transmitter is not used in passive beam forming. In this way, a digital beamformer usually consists of a transmitter (in the case of active beamforming), a receiver, and a DAS processing device, and is realized by assembling these devices. Small packages are now available at low cost.

  This DAS process uses a phase delay process that multiplies a complex exponential function in the frequency domain, which requires a huge amount of time but delays the received signal at high speed by interpolating approximation processing in the spatial domain for phasing. There is one that delays with high accuracy based on the Nyquist theorem (the first invention of the first inventor of the present application), and the received signals are added in the spatial domain after phasing (phasing addition). In a digital device, as a trigger signal for digital sampling (AD conversion) of an analog reception signal, for example, a command signal generated by a control unit may be used so that a transmitter generates a transmission signal to an element to be driven. .

  Also, when driving multiple elements with transmission delay in one beamforming, analog or digital transmission delay patterns that are mounted in advance in the transmission unit and that enable the operator to select the transmission focus position, steering direction, etc. May be used. Furthermore, in the reception digital processing, the command signal for the element to be driven first, the command signal for the element to be driven last, or the command signal for driving another element is used as a trigger signal. Sampling may be started and a digital delay may be applied. These command signals may be generated based on a command signal for starting beam forming for one frame.

  When the digital delay is performed in the transmission delay, unlike the analog delay, an error determined by the clock frequency for generating the digital control signal is inevitably generated. Therefore, the analog delay is better for the transmission delay. In addition, if a digital delay is applied in reception to realize reception dynamic focusing, an error is caused by the above-described interpolation approximation processing. Therefore, the sampling frequency of the AD converter is increased sufficiently at a cost, or the above-described high There was no choice but to apply low-speed beam forming by applying an accurate digital delay (phase rotation processing).

  In the case of the former with interpolation approximation processing, the phasing addition may simply add echo signals from the position including the coordinate position of the signal value to be generated, bi-linear or multi-dimensional polynomial The accuracy may be improved by interpolation using the above. The former is much faster than the latter, which uses a complex exponential function, but the accuracy is low. The latter is highly accurate but extremely slow. This phasing addition is often performed under the assumption that the wave propagation velocity is known or assumed to be constant within the region of interest. On the other hand, the propagation velocity is measured and phase aberration correction is performed. Before or after beamforming, for example, the cross-correlation function between adjacent beam signals or between beam signals at different angles is evaluated to evaluate the phase. Aberration can be determined (if the propagation velocity is uniform, it becomes an interferometry).

  Compared to the case where the aperture elements are distributed or arrayed in a one-dimensional space, the aperture elements are distributed in two dimensions or three dimensions, or the aperture elements constitute a two-dimensional or three-dimensional array. In some cases, it is necessary to perform more processing for beam forming, and a large number of processors are installed to perform parallel processing. In some cases, parallel reception processing is performed for beam forming at a remote position with little interference, transmission beam forming in a plurality of directions with different steering angles, and single transmission beam forming.

  In terms of communication control, it is necessary for waves to be generated appropriately, reflecting the type and amount of communication data, or the characteristics of the medium, and optimized under these observations. It is desirable that communication be performed. It is also possible to separate the interfering waves using analog devices or by analog or digital signal processing. Controlled waves of propagation direction, coding, frequency and / or bandwidth are important.

  As another invention of the first inventor of the present application similar to the above-described multidirectional aperture surface synthesis processing, it is possible to perform multidirectional reception beamforming for one transmission beamforming and improve the frame rate. . In addition, apodization may be important in beam forming. For example, each of transmission and reception apodization may be performed to reduce side lobes, but this has a trade-off relationship with lateral resolution and should be appropriately performed. On the other hand, a simple beam former that does not perform apodization is often used with an emphasis on spatial resolution. However, the first inventor of the present application reports that in order to obtain a lateral resolution while suppressing side lobes during steering, appropriate apodization is necessary. Further, in the past invention of the first inventor of the present application, there is one that removes side lobes in the frequency domain.

  In addition, contrast agents (for example, microbubbles in medical ultrasound imaging) may be used to apply the nonlinear characteristics of waves in the subject. The first inventor of the present application, including application of these, Realizes high-intensity waves and high-harmonic waves (broadband transmission), and non-linear processing on received coherent signals and coherent signals after phasing addition. Invented high-contrast imaging by suppressing resolution and side lobes. The first inventor of the present application also invented highly accurate tissue displacement (vector) measurement based on the nonlinear processing.

It is also possible to generate an imaging signal using a virtual source. As for the virtual source, there have been reports in the past of installing a virtual source before the physical aperture and installing a virtual source at the transmission focal position. Further, the first inventor of the present application may install not only a virtual source but also a detector at an arbitrary position without using a focal point, and a physical source or detector of a wave with an appropriate scatterer or diffraction grating. It is reported that it can be installed at any position. It is possible to increase the spatial resolution and widen the field of vision (FOV).

  As an imaging form, orthogonal detection, envelope detection, or square detection is used. However, the first inventor of the present application also actively displays the wave itself as a color image or a gray image. Emphasis is placed on display including phase information. As described above, development of multi-dimensional devices using various waves is under progress for various purposes.

  There are some digital beam forming using fast Fourier transform disclosed so far, and one of them is analog processing (Fourier transform is an analytical solution of classical monostatic aperture synthesis ( Digitize (see Non-Patent Document 1), and exactly perform classical aperture synthesis at high speed and with high accuracy through Fast Fourier Transform (see Non-Patent Document 2). In this process, interpolation approximation is not required, but in the case of steering (deflection) or multi-static aperture synthesis (generally, reception using the element or a plurality of peripheral elements in one-element transmission) Digital processing is not disclosed.

  All other digital beam forming disclosed requires interpolation approximation processing and has low accuracy. For example, a method of performing wave number matching through fast Fourier transform including the case of steering in plane wave transmission is disclosed (see Non-Patent Document 3-5), but in this case, the aperture shape of the array is not flat. In some cases, when calculating or displaying an image (when the array opening is an arc (see Non-Patent Document 6)), an interpolation approximation process is required, and the accuracy is low. Although the thing using the fast Fourier transformation at the time of plane wave transmission is disclosed also in patent documents 1-4, all perform wave number matching through interpolation approximation. By the wave number matching by the interpolation approximation, the multi-dimensional spectrum is obtained with the angular vector wave vector coordinate system at equal intervals, and the fast inverse Fourier transform is performed, so that the beam forming can be completed at high speed.

  Recent Non-Patent Document 5 discloses that wave number matching is Fourier-transformed with respect to non-uniform sampling signals, but this is also based on interpolation approximation processing. As mentioned above, digital beam forming has a long history, but when the most important is the real-time performance (calculation speed) until the image is displayed, interpolation approximation is often performed, providing the best accuracy. I don't mean. In addition, the most general fixed focus processing known to perform DAS processing, steering at that time, and the like are not disclosed even by a processing method performed through digital fast Fourier transform.

  There is also a report on the migration method (see, for example, Non-Patent Document 7), which also requires interpolation approximation in wave number matching. In order to obtain accuracy in processing involving these interpolation approximations, it is usually necessary to perform oversampling sufficiently by increasing the sampling frequency of the AD converter.

US Pat. No. 5,720,708 US Pat. No. 6,685,641 US Pat. No. 7,957,609 US Patent Application Publication No. 2009/0036772

J. W. Goodman, "Introduction to Fourier Optics" 2nd ed., McGraw-Hill Co, Inc., 1996 L. J. Busse, IEEE Trans.UFFC, vol. 39, no. 2, pp. 174-179, 1992 J. Cheng, J.-y. Lu, IEEE Trans UFFC, vol. 53, no. 5, pp. 880-899, 2006 H. Peng, J.-y. Lu, X. Han, Ultrasonics, 44, e97-e99, 2006. P. Kruizinga et al, IEEE Trans.UFFC, vol. 59, no. 12, pp. 2684-2691, 2012 M. A. Haun, D. L. Jones, W. D. O'Brien, Jr., IEEE Trans.UFFC, vol. 49, pp. 861-870, 2002 D. Garcia, L. L. Tarnec, S. Muth, E. Montagnon, J. Poree, G. Cloutier, IEEE Trans.UFFC, vol. 60, no. 9, pp. 1853-1867, 2013 J. A. Jensen, "Field: A program for simulating ultrasound systems," Med, Biol, Eng, Comp, 10th Nordic-Baltic Conference on Biomedical Imaging, Vol. 34, Supplement 1, Part 1: pp. 351-353, 1996

  As described above, if a digital delay is applied in reception to realize reception dynamic focusing, an error is generated according to the above-described interpolation approximation processing. Therefore, the sampling frequency of the AD converter is sufficiently increased at a high cost. Alternatively, the above-described high-precision digital delay (phase rotation processing) was applied to achieve low-speed beam forming.

  Up to now, reflected waves, transmitted waves, scattered waves (forward) are targeted for vibration waves (mechanical waves) including electromagnetic waves, sound waves (compression waves), shear waves, surface waves, etc., or heat waves. Scattered or backscattered waves, etc.), refracted waves, surface waves, shock waves, or methods of digital beamforming for those waves generated from self-emanating wave sources are disclosed. As described above, the present invention is limited to monostatic type aperture surface synthesis that does not include steering, plane wave transmission that includes steering, and the migration method. Other than the monostatic aperture plane synthesis, digital beam forming could not be performed without requiring interpolation approximation. Therefore, the accuracy was low.

  On the other hand, when using a transmission or reception transducer array device having an arbitrary aperture shape (sometimes used for both transmission and reception, or transmission and reception may be related to different waves) or passive When only receiving transducers are used in beam forming, no interpolation approximation is required, regardless of whether transmission or reception focusing or steering is used, even if the coordinate system of the transmitted and received beams is different from the coordinate system for image display. In addition, it is desired to perform arbitrary beam forming at high speed and with high accuracy.

  In the case of active beamforming, transmit and receive transducer array devices with arbitrary aperture shapes (transducers may be used for both transmit and receive) are used. In the case of passive beamforming, only a receiving transducer array device having an arbitrary aperture shape is used. In those cases, it is desired to realize arbitrary beam forming at high speed and with high accuracy by digital processing. It is desired that virtually any focusing and any steering (deflection) be performed using a transducer array device having an arbitrary aperture shape.

  After beam forming with phasing addition, linear or non-linear signal processing is performed on a plurality of beams in which at least one of wave parameters such as frequency, bandwidth, pulse shape, beam shape in each direction is different, A beam having a different value for at least one of those wave parameters may be generated (frequency modulation, wide band, multi-focus, etc.). In such beam forming, focusing is performed. Steering (deflection) and apodization are performed using a transducer array device having an arbitrary aperture shape based on DAS processing.

  The wave propagation speed is determined by the physical properties of the medium under physical conditions. Therefore, when the aperture element forms a two-dimensional or three-dimensional distribution or a multidimensional array to perform imaging in a multidimensional space, it is a one-dimensional case. Compared to, a lot of beam forming will be performed, and the number of processing data used for one beam forming will increase, so it will take a lot of time, but acquiring the high speed of beam forming, It is desirable to use a device that processes these beam formings in a so-called real time or a device that can display the results in a short time.

  Up to now, digital beam forming through Fourier transform has been disclosed through interpolation approximation in a Cartesian coordinate system mainly using a one-dimensional or two-dimensional linear array transducer. Even when the coordinate system between the reception and the result (image) display is different, it is desirable to perform digital beam forming without performing any interpolation approximation.

  A method disclosed for a case where the aperture shape of the array is not flat (for example, when the array aperture is an arc) also performs interpolation approximation. As a typical example, when a convex transducer is used, or when electronic or mechanical sector scan or IVUS (intravascular ultrasound) scan is performed, transmission and reception are performed in an arbitrary coordinate system such as a polar coordinate system. It is desired to obtain a signal that is directly beamformed in an arbitrary image display system (arbitrary coordinate system) such as a Cartesian coordinate system without processing the digital signal obtained from the wave and performing interpolation approximation.

  In recent years, memory and AD converters have become very inexpensive, but without oversampling, sampling waves based on the Nyquist theorem, it takes time to perform DAS processing that does not require interpolation approximation. It is desired that the corresponding beam forming can be performed at high speed. Proper implementation of apodization can also be important.

  As a result of solving these problems, the spatial resolution and contrast (including the effect of suppressing side lobes) of the image signal obtained in real time or in a short time are high, and the motion (displacement) of the object is obtained from the obtained signal. ), Deformation, or temperature, etc., it is desired to realize highly accurate measurement. For example, in the field of medical ultrasound, in recent years, the Doppler method has been applied to echo signals to measure tissue displacement and speed, and then subjected to spatiotemporal differentiation to obtain acceleration and strain, etc. became. Spatio-temporal differentiation is a process that amplifies high-frequency measurement errors and degrades the signal-to-noise ratio (SNR), so it is necessary to realize highly accurate displacement measurement using a phase. Conventionally, high-precision beamforming that realizes this has been dynamic focusing based on so-called DAS processing. A three-dimensional imaging apparatus using a two-dimensional array or a three-dimensional array also tends to become widespread. In this way, it is desired to achieve arbitrary beam forming including dynamic focusing at high speed and with high accuracy without interpolation approximation.

  Recently, the first inventor of the present application has developed high-accuracy of tissue displacement and shear wave propagation that move relatively quickly based on high-speed beam forming by deflection plane wave transmission (transmission and reception within a region of interest is high-speed). Although the measurement method has been realized, even when such focusing is not performed, it is desired to perform beam forming with high accuracy at high speed without requiring interpolation approximation. By performing high-speed beam forming while changing the steering angle and performing coherent addition, it is possible to obtain almost the same high image quality (spatial resolution and contrast) at high speed compared to scanning using a normal focusing beam. . High-speed beamforming is also effective for multidimensional imaging using a multidimensional array.

  In addition, steering and multistatic aperture synthesis in classical aperture synthesis (monostatic type) based on scanning by driving one element at a time, which has not been disclosed so far, do not require interpolation approximation at high speed. It is desirable to carry out with high accuracy. In addition, even when so-called migration processing is used, it is desirable to process arbitrary beam forming at high speed and with high accuracy without performing interpolation approximation in an arbitrary coordinate system. Other specific examples of beam forming that are desired to be realized are as described in other parts of the present specification, and it is desirable that these beam forming can be performed at high speed and with high accuracy as well. It is.

  Therefore, one object of the present invention is to use a digital beam former having a digital calculation function and perform arbitrary beam forming at high speed and high accuracy without performing approximate calculation.

The present invention has been made to solve at least a part of the above problems. Beamforming method according to the first aspect of the present invention is the Cartesian rectangular coordinate system using the coordinates of the transverse direction x orthogonal axial y and thereto determined by the direction of the opening of the receiving aperture element array, positioned in an arbitrary direction any wave is transmitted toward the measuring object from a wave source to the wave coming from the measurement object when receiving processed as a plane wave, the deflection of zero or non-zero formed by the reception and axial plane waves When the angle is represented by the deflection angle θ, the wave arriving from the measurement object is received by at least one receiving aperture element, and a reception signal is generated (a) and generated in step (a). (B) performing beam forming processing by performing at least Fourier transform and wave number matching on the received signal. Step (b) does not perform wave number matching including interpolation approximation processing in the wave number domain or frequency domain for the received signal, and the received signal is Fourier-transformed with respect to the axial direction y. Perform wave number matching in the horizontal direction x by multiplying by the complex exponential function (101) expressed using i,
Further, the product is Fourier transformed with respect to the lateral direction x to have a resolution with respect to the axial direction y, and a complex exponential function that can be implemented without the effect of wave number matching performed in the lateral direction x is obtained. 102) and at the same time multiplying the complex exponential function (103) to perform wavenumber matching in the axial direction, where the transverse wavenumber is represented as k _x ,
It includes directly generating an image signal in a Cartesian coordinate system by performing wave number matching without performing interpolation approximation processing.

Furthermore, beam forming method according to a second aspect of the present invention, the coordinates of the transverse direction x orthogonal to mechanical scanning or electronic scanning axially y and thereto determined by the direction of the opening of the line the Hare receive effective aperture array And a beamforming method that performs monostatic aperture synthesis to generate a beam subjected to dynamic focusing of transmission and reception in a Cartesian rectangular coordinate system having a zero y coordinate at the position of the reception effective aperture element array. Then, in the case where the zero or non-zero deflection angle formed by the axial direction and the beam direction is represented by the deflection angle θ, a step (a ′) of transmitting a wave from the transmission aperture element toward the measurement object; Receiving a wave coming from the measurement object by one of a plurality of reception aperture elements at different positions, and generating a reception signal a) and a step (b) of performing a monostatic aperture plane synthesis process having a zero or non-zero degree deviation angle θ by performing at least a Fourier transform on the reception signal generated in step (a). Step (a ′), wherein the wave is generated by at least reflection or backscattering at the measurement object, or is generated by at least transmission, forward scattering, or refraction at the measurement object. The transmission aperture element having the same x coordinate as that of the reception aperture element that generates the reception signal, and having a zero y coordinate, is one of the plurality of transmission aperture elements that also serve as the plurality of reception aperture elements. Waves are transmitted from each one of the plurality of transmission aperture elements, each having a non-zero constant y coordinate and facing the plurality of reception aperture elements. Comprises Rukoto, step (b), the wave number region _(k x, _{k y)} to the wave number of the axial direction y and a transverse direction x, respectively _{k y} and _{k x} the wavenumber domain or frequency relative to the received signal For a wave vector (0, k ₀ ) having a wave number k ₀ (= ω ₀ / c) expressed using the wave carrier frequency ω ₀ without performing wave number matching including interpolation approximation processing in the region, In order to perform dynamic focusing of transmission and reception with spectrum shifting to generate an image signal having the vector (sk ₀ sinθ, sk ₀ cosθ) as the center of gravity or instantaneous frequency of the multidimensional spectrum, the received signal is axially a parameter s having a value of 2 when the y-coordinate of the transmission aperture element is zero and a value of 1 when the y-coordinate of the transmission aperture element is non-zero. By multiplying the center of gravity frequency k _{0 of the} wave and the complex exponential function (301) expressed using the imaginary unit i, wave number matching in the lateral direction x is performed,
Further, the product is Fourier transformed with respect to the lateral direction x to have a resolution with respect to the axial direction y, and a complex exponential function that can be implemented without the effect of wave number matching performed in the lateral direction x is obtained. 302) and simultaneously performing wave number matching in the axial direction by multiplying the complex exponential function (303),
It includes directly generating an image signal in a Cartesian coordinate system by performing wave number matching without performing interpolation approximation processing.

  The above beam forming method can be easily applied to a three-dimensional case. Furthermore, an apparatus according to one aspect of the present invention receives at least one reception aperture that receives a wave coming from a measurement object and generates a reception signal, and the generated reception signal is any of the present invention. A digital signal processing unit that performs an operation of generating an image signal by performing the beamforming method according to the above aspect

  The present invention is based on the proper implementation of fast Fourier transform, complex exponential function multiplication, and Jacobi calculation, without performing the approximate calculation required in normal digital processing, An apparatus and a method for performing arbitrary beam forming at high speed and high accuracy in an arbitrary orthogonal coordinate system are included. In order to solve the problem, reflected waves, transmitted waves, and scattered waves are targeted for waves such as electromagnetic waves, vibration waves (mechanical waves) including sound waves (compression waves), shear waves, surface waves, etc., or heat waves. Waves (such as forward scattered waves or back scattered waves), refracted waves, surface waves, shock waves, those generated from self-emanating wave sources, waves emitted from moving objects, or unknown wave sources Appropriately set digital signal processing algorithms (in the implemented digital circuit or software) and analog or digital hardware are used for observed waves such as those coming from.

  The hardware configuration may include a device equipped with a normal digital beamformer phasing addition device of each wave device, and further a device having an arithmetic function for performing digital wave signal processing. May be implemented, or a digital circuit that realizes the calculation may be configured and used. As other necessary devices, at least a normally used transducer, transmitter, receiver, storage device for received signals, and the like may be provided, as described in detail later. Harmonic waves are also processed. Beam forming using a virtual source and a virtual receiver is also performed. Parallel processing is also performed to generate multiple beams simultaneously.

  In the present invention, in order to realize high-speed and high-precision processing, in addition to the analog device such as level adjustment or analog filtering by the above-described analog amplification or attenuation, an analog signal processing device (the waveform of the drive signal) Effective application of linear elements and especially non-linear elements for changing waveforms, such as emphasizing and diminishing features, as well as devices and computers with general-purpose calculation processing capabilities as described above, PLD (Programmable Logic Device) ), FPGA (Field-Programmable Gate Array), DSP (Digital Signal Processor), GPU (Graphical Processing Unit), or microprocessor may be used, but a dedicated computer or dedicated digital circuit, or Digital processing may be performed on the stored signal using a dedicated device.

  It is important that these analog devices, AD converters, memories, and devices that perform digital signal processing (multi-core, etc.) have high performance, but the number of communication between devices, communication line capacity, wiring, or Broadband wireless communication is also important. In particular, in the present invention, in addition to the case where these functional devices are appropriately mounted on one chip or substrate (when detachable), the functional devices are directly mounted on one chip or substrate. (Including lamination) is desirable. Parallel processing is also important. If the device is non-detachable, when the computer doubles as a control unit, it is possible to obtain much higher security performance than that obtained under normal program control. On the other hand, the current law will require more disclosure of processing details.

  According to one aspect of the present invention, a digital beam former having a digital calculation function can be used, and arbitrary beam forming can be performed at high speed and high accuracy without performing approximate calculation through fast Fourier transform. It becomes possible. As will be described in detail later, the present invention is based on the proper use of multiplication of complex exponential functions and Jacobi arithmetic, and can perform any beamforming at high speed in any orthogonal coordinate system including a curved coordinate system. In addition, it can be realized with high accuracy without interpolation approximation.

  Any beamforming including conventional beamforming can be realized by using a DAS (Delay and Summation) process. However, according to the present invention, when a physical aperture forms a one-dimensional array, a general-purpose PC (personal computer) is used. ), The calculation speed is significantly faster than 100 times. When the aperture elements form a two-dimensional or three-dimensional distribution or a multi-dimensional array, the problem of requiring a lot of processing time can be solved more effectively, and the high speed of beam forming becomes more effective.

  That is, according to the present invention, a transmission or reception transducer array device (which may be used for both transmission and reception) or a sensor array device having an arbitrary aperture shape is used, and an arbitrary beam forming can be interpolated at high speed. It can be realized by digital processing with high accuracy without performing it. Virtually any focusing, any steering (deflection), any apodization can be performed with an array device having any aperture shape.

  For example, in the field of medical ultrasonic imaging, in addition to the Cartesian coordinate system using linear transducers, in the convex type, sector scan, or IVUS (intravascular ultrasound), physical transmission, reception, and digitization are performed using a polar coordinate system. What is to be done is popular and can be used according to the observation target. For example, when observing the dynamics of the heart from the gap between the sternum, a sector scan is usually performed. In addition, in the case of an array-type opening shape or a PVDF (polyvinylidene fluoride) based transducer, the opening may be deformable. That is, according to the present invention, a digital signal obtained from a wave transmitted and received in an arbitrary coordinate system is processed, and a signal directly beamformed in an arbitrary coordinate system such as an image display system is obtained without interpolation approximation. be able to.

  In multi-static aperture synthesis, echo data frames composed of echo signals received at the same position among a plurality of reception positions with respect to the transmission position are generated by the number of receiving elements, and each echo is generated in the frequency domain. The data frame is subjected to monostatic type aperture surface synthesis processing according to the present invention, and the result of superimposing these processing results is subjected to inverse Fourier transform. As a result, echo data can be generated by aperture surface synthesis processing equal to the number of channels of the reception aperture, so low spatial resolution image signals are generated and superimposed by DAS, which is known as a multistatic processing method, and high spatial resolution is achieved. It is faster than the method of generating an image signal.

  Further, based on the multi-static processing according to the present invention, dynamic reception and steering at the time of general transmission fixed focus can be performed at high speed and with high accuracy. Either can be accomplished by performing an appropriate phase rotation process using complex exponential multiplication.

  As for the coordinate system, the present invention is based on performing a Jacobi operation in the Fourier transform. For example, in the convex, sector scan, or IVUS signal processing, echo data transmitted / received in the polar coordinate system is used. Based on this, echo data can be generated directly in the Cartesian coordinate system of the display system with high accuracy and high speed without interpolation approximation.

  According to the present invention, even when so-called migration processing is used, arbitrary beam forming can be processed at high speed and with high accuracy without performing interpolation approximation in an arbitrary coordinate system. Further, according to the present invention, high-SNR and high-resolution imaging using a virtual source can be performed at high speed. Furthermore, according to the present invention, the frequency modulation and widening of the beam performed under linear processing and non-linear processing, multi-focus, parallel processing, virtual source and virtual receiver, etc. are also highly accurate at high speed under digital processing. Can be realized. The present invention is also useful in the optimization of beam forming that requires a calculation amount.

  As described above, according to the present invention, for electromagnetic waves, vibration waves (mechanical waves) including acoustic waves (compression waves), shear waves, shock waves, surface waves, etc., or waves such as heat waves, Arbitrary beamforming, regardless of transmission / reception focusing, transmission / reception steering, and transmission / reception apodization, even when the coordinate system for transmitting and receiving and the coordinate system for generating the beamformed signal are different Can be performed with high accuracy and high speed without performing interpolation approximation based on digital processing.

  This not only improves the frame rate when displaying the beamformed signal as an image, but also provides high spatial resolution and high contrast in terms of image quality, and also uses the beamformed signal for displacement and deformation. Alternatively, if the temperature or the like is measured, the measurement accuracy can be improved. The high speed of processing has a great effect in multidimensional imaging using a multidimensional array. The present invention relates to a mathematical algorithm related to wave propagation, is a result of deriving a solution through digital computation but not including approximate calculation, and cannot be easily conceived.

1 is a representative block diagram illustrating a configuration example of a measurement imaging apparatus and a communication apparatus according to a first embodiment of the present invention. The typical block diagram which shows the structural example of the apparatus main body shown in FIG. 1 in detail. The schematic diagram which shows the example of arrangement | positioning of the several transmission aperture element in a transmission transducer. The block diagram which shows the structure of the receiving unit or receiver which mounts a phasing adder, and its peripheral device. The schematic diagram of the transmission of a deflection plane wave. The flowchart which shows the digital signal processing at the time of a deflection plane wave transmission. The schematic diagram in the case of transmitting a wave wide in the angle θ direction in the polar angle (r, θ) in the radius r direction (cylindrical wave transmission). Schematic diagram of a case where a wide wave is transmitted in the direction of the radius r in the angle θ direction of the polar coordinate system (r, θ) using a virtual source installed behind a physical aperture having an arbitrary aperture shape (cylindrical wave transmission) . Schematic diagram of monostatic type aperture surface synthesis. Schematic diagram of spectrum generated by steering in monostatic type aperture plane synthesis (θ is steering angle). Schematic diagram of multi-static type aperture plane synthesis. Schematic diagram of fixed focusing using a linear array. The flowchart which shows the digital signal processing at the time of cylindrical wave transmission. Schematic diagram of fixed focusing using convex array. The flowchart which shows the migration process at the time of transmitting a deflection | deviation plane wave. The figure which shows the numerical phantom used in simulation. The figure which shows the sound pressure waveform of the transmission pulse used in simulation. The figure which shows the image obtained using the method (1) in deflection | deviation plane wave transmission. The figure which shows the deflection angle and error which were obtained using the method (1) in deflection plane wave transmission with respect to a setting angle. The figure which shows the error of the deflection angle obtained using the method (1) in the deflection plane wave transmission. The figure which shows the image obtained by using the method (1) with the compound method in deflection plane wave transmission. The figure which shows the point spread function implement | achieved using the method (1) in deflection | deviation plane wave transmission. The figure which shows the image obtained using the migration method of the method (6) in deflection | deviation plane wave transmission. The figure which shows the image obtained by the monostatic type aperture surface synthesis | combination of the method (2). The figure which shows the image obtained by the multistatic type aperture surface synthesis | combination of the method (3). The figure which shows the point spread function implement | achieved by the multistatic type aperture surface synthesis | combination of the method (3). The figure which shows the image obtained by fixed focusing transmission of the method (4). The figure which shows the image acquired by the method (5-1) in the cylindrical wave transmission using a convex type | mold array. The figure which shows the image obtained by the fixed focusing transmission of the convex type | mold array and the method (5-2).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is used for the same component and the overlapping description is abbreviate | omitted. The apparatus according to the present invention can be used as a measurement imaging apparatus or a communication apparatus. In the following, mainly when the wave is a sound wave such as an ultrasonic wave, the sound pressure or the particle velocity, and as a mechanical wave, a compression wave (longitudinal wave) or a shear wave, a shock wave, a surface wave, a stress wave or When distorted waves and electromagnetic waves are targeted, image signals of electric or magnetic fields, and when heat waves are targeted, transmitted signals of temperature or heat flux, refracted waves, reflected waves, scattered waves (forward scattered waves, backward scattered waves, etc.) The case of generating will be described.

<< First Embodiment >>
First, configurations of the measurement imaging apparatus and the communication apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a representative block diagram illustrating a configuration example of a measurement imaging apparatus and a communication apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the measurement imaging apparatus and communication apparatus according to the present embodiment include a transmission transducer (or applicator) 10, a reception transducer (or reception sensor) 20, an apparatus body 30, an input device 40, An output device (or display device) 50 and an external storage device 60 are provided.

  FIG. 2 is a representative block diagram showing in detail the configuration example of the apparatus main body shown in FIG. The apparatus main body 30 mainly includes a transmission unit 31, a reception unit 32, a digital signal processing unit 33, and a control unit 34. Here, the receiving unit 32 may include a digital signal processing unit 33. 1 and 2 are appropriately simplified block diagrams, and the present embodiment is not limited to these, and details of the present embodiment are as follows. As an example, communication is appropriately performed between the devices described above, between the units in the device main body 30, and within each unit based on wired technology or wireless technology, and may be installed at a remote location. The apparatus main body 30 is composed of a plurality of such units, and is referred to as such for convenience.

<Transmission transducer>
The transmission transducer (or applicator) 10 shown in FIG. 2 generates a wave by a drive signal supplied from the transmission unit 31 in the apparatus main body 30 and transmits it. In the present embodiment, the plurality of transmission aperture elements 10a of the transmission transducer 10 form an array.

  FIG. 3 is a schematic diagram illustrating an arrangement example of a plurality of transmission aperture elements in the transmission transducer. FIG. 3 (a1) shows a plurality of transmission aperture elements 10a densely arranged in a one-dimensional array, and FIG. 3 (b1) shows a plurality of transmission aperture elements 10a sparsely arranged in a one-dimensional shape. Is shown. FIG. 3 (a2) shows a plurality of transmission aperture elements 10a that are densely arranged in a two-dimensional array, and FIG. 3 (b2) shows a plurality of transmission aperture elements 10a that are sparsely arranged in two dimensions. Is shown. FIG. 3 (a3) shows a plurality of transmission aperture elements 10a densely arranged in a three-dimensional array, and FIG. 3 (b3) shows a plurality of transmission aperture elements 10a sparsely arranged in a three-dimensional shape. Is shown.

  Each transmission aperture element 10a has a rectangular, circular, hexagonal, or other aperture shape, and may be flat, concave, or convex, and the array may be one-dimensional, two-dimensional, or There are three-dimensional ones. The directivity of one transmission aperture element 10a is determined by the frequency and bandwidth of the generated wave and the shape of the aperture of the transmission aperture element 10a, and is usually expressed in a two-dimensional space or more, but at least orthogonal. A so-called opening that faces two directions orthogonal to each other so as to have directivity in two directions may be counted as one element, and three directions that so-called openings cross so as to have directivity in three directions orthogonal to each other. There is also a case where the one suitable for the device is counted as one element. There is also an element having an opening in which the opening is directed in more directions than three directions so as to have directivity in more directions than three independent directions. They differ depending on the position and may be mixed.

  Although the transmission aperture elements 10a may exist spatially densely or sparsely (separated positions), the present embodiment will be described without being particularly distinguished from a one-dimensional to three-dimensional array type. Aperture element array is used for IVUS in linear type (element arrangement is flat), convex (convex arc arrangement), focus type (concave arc arrangement), circular type (for example, medical ultrasound) ), Spherical, convex or concave spherical shells, and other shapes that are arranged in a convex or concave shape, various aspects can be taken for objects (communication objects) that propagate waves and observation objects. However, it is not limited to these. By appropriately driving these aperture element arrays, wave transmission, steering, aperture synthesis, fixed transmission focus, etc., in which the wavefront of the plane wave or the like spreads in the horizontal direction are performed, and one beam or generated A transmission wave having a wavefront is realized.

  Regarding electronic scanning, as described in detail later, in order to generate a transmission wave having one transmission beam or wavefront, the driving is performed by independent drive signals generated by a plurality of transmission channels included in the transmission unit 31 shown in FIG. The same number of transmission aperture elements 10a as the number of signals can be driven independently. A transmit aperture element array used to generate a transmit wave having one transmit beam or wavefront is also referred to as a transmit effective aperture. Further, it is distinguished from a physical aperture element array that collectively refers to all aperture elements, and the transmission aperture realized by the transmission aperture element 10a that is driven simultaneously is also referred to as a transmission sub aperture element array or simply a transmission sub aperture. is there.

  In order to observe the entire region of interest at once when the wave propagation object (communication object) is wide, the number of transmission channels of the total number of aperture elements in the physical aperture element array is provided, and all of them can be used at all times. However, in order to reduce the cost of the apparatus, the transmission channel is electronically switched to shift the transmission sub-aperture element array (electronic scanning), or the physical aperture element array is mechanically scanned (mechanical scanning). A wave may be transmitted throughout the region of interest using a minimum number of transmission channels. When a wave propagation target (communication target) is wide or an observation target is large in size, both electronic scanning and mechanical scanning may be performed.

  When sector scanning is performed, a spatially fixed aperture element array of the above type is electronically driven and scanned (electronic scanning), or the aperture element array itself is mechanically scanned. (Mechanical scanning) or both may be performed together. In classic aperture plane synthesis, electronic scanning is performed electronically for each element of an aperture element array, or mechanical transmission of one aperture element is used to transmit at different positions to form a transmission aperture array. In this case, the transmission unit 31 may have the number of transmission channels corresponding to the number of elements of the physical aperture array. However, if a switching device is used, the number of transmission channels can be reduced. Need. When transmitting polarized waves, the transmission unit 31 needs to have at least the number of channels obtained by multiplying the number of elements driven at one time by the number of polarized waves.

<Receiving transducer>
The reception transducer (or reception sensor) 20 shown in FIG. 2 may also serve as the transmission transducer 10, but may be an array type sensor dedicated to reception that is used separately from the transmission transducer 10. Accordingly, the receiving transducer 20 may be set at a position different from that of the transmitting transducer 10. The receiving transducer 20 may sense a wave different from the wave generated by the transmitting transducer 10. Such a receiving transducer 20 may be installed at the same position as the transmitting transducer 10 or may be integrated.

  As in the case of the transmission transducer 10, the reception transducer 20 in the present embodiment includes at least one reception aperture element 20 a constituting an array, and signals received by the respective elements are in an independent state in the apparatus main body 30. To the receiving unit 32 (FIG. 2). Similar to the transmission aperture element 10a, the reception aperture element 20a has a rectangular, circular, hexagonal, or other aperture shape, and may be flat, concave, or convex. There are dimensions, two dimensions, or three dimensions. The directivity of one reception aperture element 20a is determined by the frequency and bandwidth of the wave to be received and the shape of the aperture of the reception aperture element 20a, and an element having a plurality of apertures may be counted as one element. The number of openings in one element varies depending on the position and may be mixed. Further, there are cases where the reception aperture elements 20a are spatially dense or sparse (separate positions), and are not distinguished from the array type here (see the example of the transmission array in FIG. 3).

  Similar to that of the transmission transducer 10, the aperture element array is linear type (element arrangement is flat), convex (convex arc arrangement), focus type (concave arc arrangement), circular type (for example, For objects that propagate waves (communication objects) and observation objects such as spherical, convex or concave spherical shells, and other shapes that are aligned in a convex or concave shape. However, various aspects are taken, and the present invention is not limited to these. Waves are received using these aperture element arrays, and wave reception, steering, aperture synthesis, fixed reception focus, dynamic focus, etc., in which the wavefront of the plane wave or the like spreads widely in the lateral direction, is performed. Received waves with beams and generated wavefronts are realized.

  Transducer apertures (elements) are not spatially dense and may exist in sparse (remote positions), and the measurement target may be mechanically scanned and transmitted or received. In the case of using a transducer that is not referred to as an array type, the received signal may be processed in the same manner. However, in this application, the case where an array type device is used is described without particular distinction. The present invention will be described. For example, when there is a radar aperture at a remote location on land, each radar may or may not constitute an array.

  In addition to radar mounted on satellites and airplanes, the object to be measured may be mechanically scanned by a transducer. Even in such a case, the transducer may or may not form an array. The signal may be transmitted or received continuously in high density or spatially sparsely in remote locations. Therefore, in addition to classical aperture plane synthesis (transmission by a single aperture element), signals may be received while performing transmit beamforming. The aperture element may exist in a one-dimensional form, or may exist in a two-dimensional or three-dimensional space. In addition, mechanical scanning may be performed while performing electronic scanning.

  Regarding electronic scanning, as will be described in detail later, in order to realize a reception wave having one reception beam or a generated wavefront, independent reception signals of the number of reception channels included in the reception unit 32 are received at a time at the aperture element. (The reception effective aperture is determined). The reception effective aperture may be different from the transmission effective aperture. It is distinguished from a physical aperture element array that collectively refers to all aperture elements, and the reception aperture realized by the reception aperture element 20a used at the same time may be referred to as a reception sub aperture element array or simply as a reception sub aperture.

  In order to observe the entire region of interest at a time when the wave propagation object (communication object) is wide, the receiving unit 32 includes the number of reception channels of the total number of aperture elements provided in the physical aperture element array. All may be used, but in order to reduce the cost of the device, the receiving channel is electronically switched to shift the receiving sub-aperture array (electronic scanning), or the physical aperture element array is mechanically scanned. (Mechanical scanning) may receive waves coming from the entire region of interest using a minimum number of received channels.

  When a wave propagation target (communication target) is wide or an observation target is large in size, both electronic scanning and mechanical scanning may be performed. When a sector scan is performed, a spatially fixed aperture element array of the above type is electronically driven to scan while repeating transmission and reception (electronic scanning), or The aperture element array itself may be mechanically scanned (mechanical scanning) or both may be performed together. Also, in the classic aperture plane synthesis, as described above, transmission is performed at different positions through electronic scanning that is electronically driven for each element of the aperture element array or mechanical scanning of one aperture element as described above. In order to constitute the transmission aperture array, the transmission unit 31 may have as many transmission channels as the number of elements of the physical aperture array in electronic scanning. However, at least one channel is always required by using a switching device as in the case of mechanical scanning. Need.

  On the other hand, regarding the reception at that time, in the case of the monostatic type in which reception is performed only by the same element as the active transmission element, the reception unit 32 may be provided with the reception channel in the same manner as the transmission channel. Further, in the multi-static type in which reception is often performed by a plurality of surrounding elements including active transmission elements, the reception unit 32 may have the number of reception channels corresponding to the number of elements of the physical aperture array in electronic scanning. By using the switching device, it is only necessary that the receiving unit 32 has at least the number of reception channels equal to the number of elements of the reception effective aperture in both electronic scanning and mechanical scanning. When receiving polarized waves, the receiving unit 32 needs at least the number of channels obtained by multiplying the number of receiving elements by the number of polarized waves.

<Specific examples of transducer>
There are various transducers 10 or 20 that can generate or receive electromagnetic waves, light, dynamic vibrations, sound waves, or arbitrary waves such as heat waves. For example, the transducer 10 may transmit an arbitrary wave to the measurement target and receive a reflected wave reflected in the measurement target, a backscattered wave, or the like (also serves as the transducer 20). For example, when an arbitrary wave is an ultrasonic wave, an ultrasonic transducer that transmits an ultrasonic wave according to a drive signal and receives the ultrasonic wave to generate a reception signal can be used. It is well known that the ultrasonic elements (PZT, polymer piezoelectric elements, etc.) are different and the structure of the transducer is different depending on the application.

  In medical applications, blood flow measurement has historically used narrow-band ultrasound, but the first inventor of the present application has discovered the displacement and strain of soft tissue that has been put into practical use in recent years (static Including the measurement of shear wave propagation (velocity), the use of a broadband transducer for (echo) imaging has been realized for the first time in the world. As with HIFU treatment, continuous wave may be used, but the first inventor of the present application has also developed an applicator using a broadband device in order to realize high-resolution treatment. Yes. When intense ultrasound is used, tissue is stimulated within a range that does not produce a heating effect, and a force source may be generated in the measurement target as described above. A transducer for (echo) imaging is used. Sometimes. Heat treatment, force source generation, and (echo) imaging may be performed simultaneously. The same applies to other wave sources and transducers.

  There are two types of transducers: contact type and non-contact type. Each time, an alignment material is used (in the case of ultrasonic waves, gel, water, etc.), or an alignment material is previously incorporated in the transducer (ultrasonic wave). In this case, the matching layer is used, and the impedance matching of each wave is appropriately performed on the object to be measured. Aperture element level and array include power, carrier frequency, bandwidth (determines broadband or narrow bandwidth, axial spatial resolution), waveform shape, element size (determines lateral spatial resolution), directivity, etc. Those designed in both aspects of performance are used (details omitted). As ultrasonic transducers, there are composite ones such as those in which PZT and PVDF are laminated and have both transmission acoustic power and broadband characteristics.

  In the case of forced oscillation by the drive signal, the frequency and band of the generated ultrasonic wave may be adjusted or encoded by the drive signal (with respect to reception, the signal in the transducer band Or band selection using analog or digital filters). In some cases, aperture elements having different characteristics such as frequency and sensitivity are arranged. Medical ultrasonic transducers were originally handy and easy to use, but recently, non-cable type transducers have been used with handy size device bodies. If the sound has a low frequency (for example, an audible sound), there are a speaker and a microphone. Other wave transducers may be realized from a similar point of view, but are not limited thereto.

  Alternatively, the transducer 10 may be a transmission transducer that generates an arbitrary wave, and the transducer 20 may be a reception transducer (sensor) that receives the arbitrary wave. In that case, the transmitting transducer transmits an arbitrary wave to the measurement target, and the sensor reflects the reflected wave or the back-scattered wave reflected in the measurement target, or the transmitted wave transmitted through the measurement target or the like. Refractive waves, forward scattering, etc. can be received.

  For example, when an arbitrary wave is a heat wave, a heat source that is not intentionally generated such as sunlight, lighting, or metabolism in the living body may be used, but an infrared heater, heater, etc. Ultra-sound transducers that transmit heating ultrasonic waves that are often controlled according to drive signals (sometimes generating a force source in the measurement target), electromagnetic wave transducers, lasers, etc. used. Infrared sensors that receive heat waves and generate received signals, pyroelectric sensors, microwave and terahertz wave detectors, temperature sensors such as optical fibers, and ultrasonic transducers (temperature dependence such as ultrasonic sound velocity and volume change) The temperature change can be detected by using a magnetic property) or a nuclear magnetic resonance signal detector (temperature can be detected by using a chemical shift of nuclear magnetic resonance). For each wave, a transducer that can receive properly is used.

  Optical digital cameras and mammography use CCD (charge coupled device) technology, and an integrated circuit and a sensor body may be integrated. The same technology is also applied to an ultrasonic two-dimensional array, and real-time three-dimensional imaging is possible. A combination of scintillator and photocoupler is used for X-ray detection, but it has been a long time since it can be observed as a wave. In capturing a high-frequency signal as a digital signal, it is effective to perform analog detection or modulation for pre-processing, and to perform AD conversion at a low frequency and store it in a memory or a storage device (storage medium). Sometimes digital detection is performed. These may be integrated by a chip or a substrate together with a transmitter and a receiver.

  In addition, for example, each aperture may form an array, such as when a radar is located at a remote location on land, and there are cases where the aperture is not limited thereto. The aperture may be scanned mechanically to obtain a wide directivity. Openings are irregular in a spatially continuous high density, spatially sparse at distant locations, at regular intervals, etc., and under physical constraints In some cases, it is installed. In addition, the position may be fixed with respect to the object (communication object) to propagate the wave and the observation position, such as in the ocean, in a building, or indoors. They may be dedicated openings for wave transmission or reception. In addition, each opening may serve as both, but it does not necessarily receive a response of a wave transmitted by itself, and may receive a wave transmitted by another opening. In medical and biological observations, it is called photoacoustic, and ultrasonic waves generated by laser irradiation may be observed (multiple wave transducers may be integrated). In some cases, a magnetic substance having an affinity for a lesion is injected intravenously as a contrast medium, and vibrations such as ultrasonic waves are applied to the affected area to observe electromagnetic waves (the past invention of the first inventor of the present application). It may communicate with various mobile objects using radio waves.

  There are various transducers (arrays) used for passive observation such as seismic waves (seismic meters), magnetoencephalograms (SQUID arrays), brain waves, neural networks (electrode arrays), radio waves (antennas), radars, etc. It may be used for observation of wave sources. The propagation direction of the arriving wave is obtained based on multidimensional spectral analysis (the past achievements of the first inventor of the present application), and in the device of the present invention, a plurality of transducers or receptions provided at different positions Even when the information about the propagation time cannot be obtained using the effective aperture (usually, the position of the wave source is determined from the time when the wave is observed at a plurality of positions), the position of the wave source is geometrically determined. It is possible to determine. Waves can be observed with continuous waves instead of pulse waves and burst waves. Through any process, when the direction of arrival of the wave is known, various beams can be steered and focused in that direction for detailed observation. In those processes, receive beamforming is always performed while changing the steering angle, focusing on the likely direction, and the resulting image or imaging, spatial resolution, contrast, signal strength, etc. are observed, or The direction of the wave source can also be specified through multidimensional spectral analysis. Therefore, the transducer used in the apparatus of the present invention is also used for steering and may be provided with a mechanism for performing electronic scanning, mechanical scanning, or both scanning.

  As transducers that can demonstrate the effectiveness of the present invention, some typical transducers that are relatively familiar and special ones are listed, but those used in the present invention include those including applications. The present invention is not limited, and various types that can generate or receive electromagnetic waves, light, dynamic vibrations, sound waves, or arbitrary waves such as heat waves can be used.

<Beam forming>
One or more beam forming at each aperture at the same time, or at the same time or at the same time, or at the same time or in the same state of the object to be propagated (communication object) or observation object Alternatively, transmission or reception may be performed. Similarly, one or more beamforming or transmission or reception may be performed with one combination of apertures. Similarly, each of a plurality of combinations of apertures may perform one or more beamforming, transmission, or reception. In these cases, new data may be generated through linear or non-linear calculations using them, including cases where a plurality of beamforming and reception results are obtained.

  Also, for example, in the case of a spatially moving object such as a radar mounted on a satellite or an airplane, the mounted aperture may or may not constitute an array, and mechanical scanning may be performed. In some cases, wide directivity can be obtained, and the regularity such as spatially continuous high density, spatially sparseness at a distant position, or equidistant spacing. Alternatively, transmission and reception may be performed irregularly as necessary. There are various other moving objects such as cars, ships, trains, submarines, and mobile robots. In addition, there are cases where things such as distributed items, creatures, etc. move regularly or randomly. In such a case, a movable communication device is used. An RFID (Radio Frequency Identification) tag, an IC card, or the like may be used.

  At that time, not only classical aperture synthesis (aperture synthesis based on transmission for each aperture element) is performed, but reception beamforming may be performed while generating transmission beamforming. In addition, mechanical scanning may be performed regularly or irregularly while electronic scanning is performed. Waves are propagated appropriately over a wide spatial range (communication), and a wide spatial range is appropriately observed. Sometimes. Of course, by using a multi-dimensional array, waves can be appropriately propagated over a wide spatial range (communication) only by electronic scanning, or a wide spatial range can be appropriately observed (physical aperture). Not only increases but also allows multi-directional steering).

  The mounted aperture may serve as both apertures for wave transmission and reception, but not only receive the response of the wave transmitted by itself, but also receive the wave transmitted by any other aperture Sometimes. In addition, a plurality of moving objects may have openings, and at the same time, a simultaneous phase in which the wave propagation target (communication target) and the state of the observation target are the same or substantially the same, or another time or In another time phase, one or more beamforming, or transmission or reception may occur at each aperture.

  Similarly, one or more beamforming, transmission, or reception may be performed with one combination of apertures. Further, similarly, each of a plurality of combinations of apertures may perform one or more beam forming, transmission, or reception. Also, in these cases, new data may be generated through linear or non-linear calculations using them, including cases where a plurality of beamforming and reception results are obtained. In the above, a combination of an aperture of a moving object and a fixed aperture may be used for an object (communication object) for propagating a wave or an observation object.

  Thus, in the present embodiment, there are a plurality of transmission aperture elements 10a and a plurality of reception aperture elements 20a (one aperture element may serve as both the transmission aperture element 10a and the reception aperture element 20a). Beam forming is actively performed. In this active beamforming, arbitrary beamforming can be realized by digital processing without performing high-speed interpolation approximation through fast Fourier transform. Also, virtually any focusing and any steering can be implemented using a transducer array device having any aperture shape.

  The transmission is generally performed in an orthogonal coordinate system determined by the shape of the physical aperture element array in order to place importance on the direction of each aperture element (virtual sound source will be described separately). In order to generate a signal directly representing a wave in a simple display coordinate system, it is mainly to perform reception digital beam forming without performing interpolation approximation processing. There is also forming.

<Transmission unit>
Next, the transmission unit 31 (FIG. 2) provided in the apparatus main body 30 will be described. The transmission unit 31 includes a plurality of transmission channel transmitters 31a. The number of transmission channels is the number of lines for sending different drive signals to the aperture elements used for performing one beamforming. For example, as described below, there are various forms of this transmission channel. The frequency, bandwidth, waveform, and directivity of the wave generated in each transmission aperture element 10 a are determined by the transmission aperture element 10 a and the transmission unit 31.

  When an impulse signal is applied to the transmission aperture element 10a, a wave determined by the shape (thickness and size and shape of the aperture) of the transmission aperture element 10a and the material (single crystal as a typical ultrasonic element) is generated. The frequency and band of a wave generated by forcibly exciting the transmission aperture element 10a with a drive signal generated in the transmission unit 31 and having a frequency, a bandwidth, and a waveform (which may be encoded) The width, waveform, and directivity are adjusted. The characteristics of the generated drive signal are set as parameters under the control of the control unit 34. Although the control unit 34 recognizes the transducer to be used and the recommended setting may be automatically performed, the setting or adjustment using the input device 40 is also possible.

  Normally, in order to drive a plurality of aperture elements with drive signals multiplied by different delays when performing one beam forming, the transmission unit 31 is equipped with an analog or digital delay pattern, and an operator can input the input device 40. A delay pattern that realizes a transmission focus position, a steering direction, and the like that can be selected using the. These patterns are programmable, and the patterns to be used and selectable patterns may be installed through various media such as a CD-ROM, a floppy (registered trademark) disk, or an MO depending on the purpose. In some cases, a program can be started and a pattern can be selected interactively from the input device 40, a delay (pattern) value can be directly input, or a file in which data is recorded can be read and set. There are cases. In particular, in the case of an analog delay, the delay value to be used may be changed in an analog or digital manner, or the delay circuit or the pattern itself may be replaced with another one or switched.

  In the apparatus main body 30 (FIG. 2), a command signal for generating a drive signal (which may be encoded) for driving the corresponding transmission aperture element 10a is transmitted from the control unit 34 to the transmitter 31a of a plurality of channels. The These command signals may be generated based on a command signal for starting beam forming for one frame. When the transmission delay is digital, for example, a digital delay is applied with a command signal sent to the transmitter 31a for the transmission aperture element to be driven first as a trigger, and the command signal is sent to each transmitter 31a. is there. A digital circuit delay device may be used for the digital delay.

  In addition, an analog delay may be applied to the drive signal itself generated in the transmitter 31a for the element to be driven first, and transmitted to each aperture element. In this case where an analog delay that does not require synchronization is used, the transmitter 31a can drive a plurality of transmission aperture elements 10a with at least one device. Therefore, the transmission analog delay is provided before and after or inside the transmitter 31a or in the control unit 34, while the transmission digital delay is provided in or before the transmitter 31a or in the control unit 34. There is.

  A pattern may be selected by switching between an analog circuit or an analog device, or a digital circuit or a digital device, but the delay of these delay devices may be changed under the control of the control unit 34. It may be programmable through installation, input settings, and the like. In addition, a delay device may be provided in the control unit 34. Further, when the control unit 34 is configured by a computer or the like as described below, a command signal delayed by software control may be directly output from the control unit 34.

  The control unit 34 and the digital delay are devices and computers having general-purpose calculation processing capability, PLD (Programmable Logic Device), FPGA (Field-Programmable Gate Array), DSP (Digital Signal Processor), GPU (Graphical Processing Unit), or , A microprocessor, etc., or a dedicated digital circuit or a dedicated device. They are desirably high performance (such as multi-core) and may also be responsible for analog devices, AD converter 32b, memory 32c, and / or digital signal processing unit 33 that performs transmit or receive beamforming processing.

  In addition, the number of communication between devices, communication line capacity, wiring, or broadband wireless communication is important. In particular, in the present invention, when these functional devices are appropriately mounted on one chip or substrate ( Detachable). In addition, they may be directly mounted on one chip or substrate (including stacking). Parallel processing may be performed. If the device is non-detachable, when the computer also serves as the control unit 34, it is possible to obtain much higher security performance than security obtained under normal program control. On the other hand, the current law will require more disclosure of processing details.

  Some control software and delay values are coded or input directly, and some are installed. The method of applying the digital delay is not limited to these. When this digital delay is performed in the transmission delay, unlike the analog delay, an error determined by the clock frequency for generating the digital control signal is inevitably generated. Therefore, in terms of accuracy, the transmission delay is preferably the analog delay. Basically, a high clock frequency is used at a cost to reduce errors. On the other hand, the analog delay can be changed in an analog manner, or can be made digitally programmable. However, the degree of freedom is lower than that of a digital delay, and when the cost is reduced, a delay pattern mounted as an analog circuit may be switched and used.

  Note that the transmission apodization is performed by changing the energy of the driving signal of the aperture element and the time change of the amplitude of a waveform (which may be encoded) that changes with time. The drive signal is adjusted based on the calibration data of the conversion efficiency (convertibility) of the drive signal of the aperture element into the wave. For other purposes, adjustments to the drive signal may be performed solely for calibration purposes. The command signal sent from the control unit 34 to the transmitter 31a may represent the waveform and phase information of the drive signal generated by the transmitter 31a as a time series, or the transmitter 31a recognizes the predetermined signal. It may be an encoded signal that can generate a drive signal, or it simply gives a transmission command to the transmitter 31a that generates a predetermined drive signal for the position of each aperture element to be driven within the effective aperture. There may be.

  Similarly to the delay, the transmitter 31a may be programmable so as to generate a predetermined drive signal for the position of each aperture element to be driven within the effective aperture, and can take various forms. A power supply or an amplifier is used to generate a drive signal, but power supplies with different power or energy supply amounts or amplifiers with different amplification levels are switched and used simultaneously to generate one drive signal. In addition, as with the transmission delay pattern, it may be set directly or programmable as described above. The delay and the apodization can be implemented in the same or different forms at the same or different hierarchical levels in the transmission unit.

  The transmission channel for driving the aperture element in the transmission effective aperture is switched through a switching device such as a shift register or a multiplexer, and the region of interest is scanned while performing beam forming using the effective aperture at another position. There is. Some delay elements have variable delay values, and delay patterns (delay element groups) may be switched. Further, steering in a plurality of directions may be performed at one effective opening, and further steering may be performed in a plurality of directions while appropriately changing the opening position and the effective opening width.

  In the case of switching a high voltage signal, a dedicated switching device is used. In some cases, the apodization value of the apodization element is variable in the transmission time direction and the array direction of the aperture element, and the apodization pattern (apodization element group) may be switched, and the aperture position, range direction, or steering direction Depending on the beam shape, the beam shape may be adjusted. Specifically, it means that a transmitting element with zero apodization value is not active and is off, and apodization can also act as a switch for the effective element and can determine the effective aperture width (apodization in the direction of the aperture element array). If the function is a rectangular window, the switch is on. If it is not a constant value, the switch is on).

  Further, regarding the delay pattern and the apodization pattern, the apparatus main body 30 may be provided with a plurality of patterns or may be programmable. Based on the response from the transmission target and the result of beam forming by the receiving unit 32 described below, In the digital signal processing unit 33 (FIG. 2) in the apparatus main body 30 to be described later, wave attenuation and scattering (forward scattering, back scattering, etc.), transmission, reflection, refraction, or sound velocity frequency dispersion in a propagation medium. And spatial distribution may be calculated, and the delay and intensity of the wave transmitted from each aperture, the steering direction of the beam and wavefront, the apodization pattern, etc. may be optimized.

  In addition, in the classical aperture plane synthesis, there are a monostatic type and a multistatic type performed in transmission by a single aperture element, and the active transmission aperture element 10a is subjected to switching or apodization as described above. Can be switched. In some cases, all transmission elements have a transmission channel including the transmitter 31a. In aperture plane synthesis, it is necessary to generate a wave of sufficient intensity or energy, and the transmission apodization function itself is not necessarily important. In practice, the aperture plane synthesis is usually performed simultaneously with reception apodization in the phasing adder, and in the present invention, it is often performed simultaneously with reception apodization in the digital signal processing unit 33. The representative transmission unit of the present embodiment has been described above. However, any transmission unit that can perform transmission beamforming can be used, and is not limited to the description.

<Receiving unit and digital signal processing unit>
Next, the receiving unit 32 and the digital signal processing unit 33 (FIG. 2) included in the apparatus main body 30 will be described. The reception unit 32 includes a receiver 32a of a plurality of reception channels, an AD converter 32b, and a memory (or storage device or storage medium) 32c. The frequency, bandwidth, waveform, and directivity of the reception signal generated in each reception aperture element are determined by the reception aperture element 20a and the reception unit 32. When the wave arrives at the reception aperture, a reception signal is generated which is determined by the shape (thickness or size and shape of the aperture) of the reception aperture element 20a and the material (single crystal as a typical ultrasonic element). The frequency, bandwidth, and directivity of the received signal generated by the filtering process in the unit 32 (which may also serve as an analog amplifier) are adjusted. The generated reception signal is substantially adjusted based on filter parameters (frequency characteristics such as frequency and bandwidth) set under the control of the control unit 34. Although the control unit 34 recognizes the transducer to be used and the recommended setting may be automatically performed, the setting or adjustment using the input device 40 is also possible.

  A normal digital receiving unit or digital receiving apparatus has such a function, and further has a phasing addition function. That is, the DAS process in the digital reception unit or the digital reception apparatus performs a phasing process on a plurality of reception signals and adds the plurality of reception signals subjected to the phasing process. As the phasing process, the received signals are AD-converted in the reception channels of a plurality of reception apertures, and are basically stored in a memory, a storage device, a storage medium, or the like that can be read and written at high speed. It takes a lot of time to delay the reception signal read from the storage destination by interpolating approximation processing in the spatial domain in order to adjust the phase of interest, but it takes a lot of time. , The delay is applied with high accuracy based on the Nyquist theorem by phase rotation multiplied by a complex exponential function (the first invention of the present inventor of the present application). In addition, at the storage destination, the reception signals of the respective reception openings may be stored at positions corresponding to the reception delay, and these reception signals are read out and added, or the above processing is further performed on them. May be added.

  FIG. 4 is a block diagram showing a typical configuration of a receiving unit or a receiving apparatus equipped with a phasing adder that realizes a phasing addition process and its peripheral devices. The receiving unit (or receiving device) 35 shown in FIG. 4 performs a phasing addition process in addition to a receiver 35a, an AD converter 35b, and a memory (or storage device or storage medium) 35c of a plurality of receiving channels. A phasing adder 35d to perform and another data generation unit 35e for digitally processing the generated image signal are provided. For example, the other data generation unit 35e generates image display data, calculates a displacement based on the Doppler method, calculates a temperature, and the like by a high-order calculation. Perform analysis.

  By performing this phasing addition process at each position in the region of interest, dynamic focusing is performed. Originally, dynamic focusing was a term used in the range direction received at the effective aperture, but in fact, it is not limited to the reception digital beamforming performed by the present invention. The receiving unit 32 in the embodiment of the present invention shown in FIG. 2 is a high-precision digital that does not require high-speed and approximation processing that is different from the above-described calculation processing represented by its name in the calculation process for performing phasing addition (DAS) processing Beam forming is performed. Therefore, in the embodiment of the present invention, the digital signal processing unit 33 shown in FIG. 2 is used instead of the phasing adder 35d shown in FIG. In the digital signal processing unit 33, other data as described above may be generated based on the image signal.

  A normal phasing adder can be similarly realized by the digital signal processing unit 33 in the embodiment of the present invention. In particular, the feature of the receiving unit 32 in the embodiment of the present invention is high speed and high accuracy. In order to realize the processing, normally, the received signal generated in the receiving aperture element 20a is level-adjusted or analog-filtered by analog amplification or attenuation (programmable and operates under the frequency characteristics and parameters set through the control unit 34. In addition to ensuring signal strength and reducing noise using analog devices such as), the advantage of analog signal processing being faster than digital signal processing is linear or particularly non-linear as required Through the effective use of devices that perform analog signal processing and through those processing The resulting signal is AD converted and stored in the fast memory (or storage device or storage medium) 32c of reading and writing digital signal obtained as a result.

  Further, as the digital signal processing unit 33 to be mounted, a device or a computer having general-purpose calculation processing capability, a PLD (Programmable Logic Device), an FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), a GPU (Graphical Processing). Unit) or a microprocessor or the like, or a dedicated computer, a dedicated digital circuit, or a dedicated device is used, and the digital wave signal processing of the present invention is performed on the stored digital signal. Applied.

  It is important that these analog devices, AD converter 32b, memory (or storage device or storage medium) 32c, and device responsible for digital signal processing unit 33 (multicore, etc.) have high performance. The number of communications, communication line capacity, wiring, or broadband wireless communication is important. In particular, in the present invention, when these functional devices are properly mounted on a single chip or substrate (when removable) In addition, they may be directly mounted on a single chip or substrate (including stacked layers). Parallel processing may be performed.

  When the device is non-detachable, it is possible to obtain much higher security performance than the security obtained under normal program control when the computer also serves as the control unit 34. On the other hand, the current law will require more disclosure of processing details. The digital signal processing unit 33 may also serve as a control unit 34 that sends command signals to other units and controls them.

  In the receiving unit 32 implemented in the present invention, a trigger signal (that is, starting AD conversion) that causes the AD converter 32b to start sampling (AD conversion) of the reception signal generated in the reception transducer (or reception sensor) 20 is performed. The acquisition start command signal (starting to store the digital signal in the memory (or storage device or storage medium) 32c) is the same as the trigger signal used in the normal receiving unit. For example, any command signal generated by the control unit 34 may be used so that the transmitter 31a generates a transmission signal to the transmission aperture element 10a to be driven. When receiving a wave, a command signal for the element to be driven first, a command signal for the element to be driven last, or a command signal for driving another element is used. AD conversion may be started by applying a digital delay.

  These command signals may be generated based on a command signal for starting beam forming for one frame. In other words, the number of occurrences of the transmission trigger signal is counted, and the hardware or the number that has reached a predetermined number or a programmable parameter such as input and set from the input device 40 or the like as appropriate is reached. When confirmed in the control program, a command signal may be generated that initiates the generation of a new frame. The number may be installed through various media such as a CD-ROM, floppy (registered trademark) disk, or MO as well as other parameters. There are cases where the program can be started and interactively selected from the input device 40, and there are various cases such as inputting a numerical value directly, or reading and setting a file in which data is recorded. The number can also be determined using a dip switch or the like. When the number of reception delay patterns is not required to be large, a signal obtained by multiplying a received signal by an installed analog delay pattern may be AD converted.

  In order to realize high-speed reception dynamic focusing, it is usual to use a product based on the Nyquist theorem by applying a product of a complex exponential function to a signal in the frequency domain which is the past invention of the first inventor of the present application. When a high-speed reception digital delay is applied, an error determined by the AD conversion sampling interval is generated. Therefore, the sampling frequency of the AD converter 32b is sufficiently increased or a high-precision digital delay (phase rotation is performed). The only thing that could be done was low-speed beamforming. On the other hand, according to the present invention, if the received signal is digitally sampled in synchronism as described above, high-speed received digital beamforming can be performed without causing such an approximation error. Such reception digital beam forming is much faster than the method of calculating the product of complex exponential functions in the frequency domain, which is the past invention of the first inventor of the present application.

  In the present invention as well, normally, the number of channels for transmitting a signal received by the reception aperture element 20a used for performing one beamforming to the reception unit 32 is the number of reception channels. In that respect, the receiving unit 32 is as follows, and there are various types of receiving channels. That is, in order to apply different delays to the signals generated in the plurality of reception aperture elements 20a when performing normal beam forming once, the reception unit 32 is equipped with an analog or digital delay pattern as described above. A delay pattern that realizes a reception focus position, a steering direction, or the like that can be selected by the operator using the input device 40 may be used.

  These patterns are programmable, and patterns to be used and selectable patterns may be installed through various media such as a CD-ROM, a floppy (registered trademark) disk, or an MO depending on the purpose. In some cases, a program can be started and a pattern can be selected interactively from the input device 40, a delay (pattern) value can be directly input, or a file in which data is recorded can be read and set. There are cases. In particular, in the case of analog delay, the delay value to be used may be changed in an analog or digital manner, or the delay circuit or pattern itself may be replaced with another one or switched separately. Sometimes.

  When the reception delay is digital, the reception signal stored in the memory (or storage device or storage medium) 32c of each reception channel is read and phased (added). In the apparatus of this embodiment, the digital signal processing unit 33 delays the digital reception signal, passes the digital reception signal through the delay device of the digital circuit, or the AD converter 32b and the memory (or storage device or It is possible to apply a delay to the command signal to start loading from the control unit 34 for turning on the storage medium 32c. Therefore, the digital delay can be applied at an arbitrary position or in the control unit 34 as long as it is after the inside of the AD converter 32b.

  In the case of an analog delay, a delay can be applied at an arbitrary position or in the control unit 34 as long as a reception signal is generated in the reception aperture element 20a. When the analog delay pattern is used, the receiver 32a can receive the reception signals of a plurality of aperture elements with at least one device. Therefore, in the storage destination of the reception signal, the reception signal of each reception opening may be stored at a position corresponding to the reception delay, or the reception delay may not be applied at all. The digital signal processing unit 33 may perform digital wave signal processing described later (the digital signal processing unit 33 may also perform normal phasing addition processing).

  A pattern may be selected by switching between an analog circuit or an analog device, or a digital circuit or a digital device. In addition, the delays of these delay devices may be programmable under the control of the control unit 34, or may be programmable through installation, input settings, or the like. Further, a delay device may be provided in the control unit 34. When the control unit 34 is configured by a computer or the like as described above, a command signal delayed by software control is controlled. It may be output directly from the unit 34.

  The control unit 34 and the digital delay may be a device or a computer having general-purpose calculation processing capability, a PLD, FPGA, DSP, GPU, or a microprocessor, or a dedicated digital circuit or a dedicated device. They are desirably high performance (such as multi-core) and may also be responsible for analog devices, AD converter 32b, memory 32c, and / or digital signal processing unit 33 that performs transmit or receive beamforming processing.

  In addition, the number of communication between devices, communication line capacity, wiring, or broadband wireless communication is important. In particular, in the present invention, when these functional devices are appropriately mounted on one chip or substrate ( Detachable). In addition, they may be directly mounted on one chip or substrate (including stacking). Parallel processing may be performed. If the device is non-detachable, when the computer also serves as the control unit 34, it is possible to obtain much higher security performance than security obtained under normal program control. On the other hand, the current law will require more disclosure of processing details. Some control software and delay values are directly coded or input, and others are installed. The method of applying the digital delay is not limited to these.

  In the present embodiment, a trigger signal (command signal) for instructing the start of AD conversion based on the trigger signal sent from the control unit 34 (FIG. 2) of the apparatus body 30 is the AD of each reception channel. It is supplied to the converter 32b. In accordance with this command signal, AD conversion of the received analog signal of each channel and storage of the digitized signal in the memory (or storage device or storage medium) 32c are started. The transmission unit 31, the reception unit 32, and the digital signal processing unit 33 are controlled by the control unit 34 until the reception signal for one frame is completely stored, or the transmission aperture position, the transmission effective aperture width, or While changing the transmission steering direction, etc., every time a wave or beam is transmitted, the process from transmission to storing the digital signal is repeated while changing the reception aperture position, reception effective aperture width, or reception steering direction. Each time a received signal for one frame is stored, a digital wave signal processing method used in the present invention, that is, a digital beam forming method is applied to the received signal group to generate a coherent signal.

  Therefore, even if the device according to the present invention is equipped with the above-mentioned analog or digital delay, it is not necessarily used as a delay for beam forming, and it saves memory, a storage device, or a storage medium. In order to effectively use the data and shorten the access time, it may be used to delay the timing of starting AD conversion of received signals and storing them in the memory (or storage device or storage medium) 32c. The reception delay in beam forming is always digital wave signal processing performed by the digital signal processing unit 33, and in the present invention, the significance of saving and shortening of access time is significant. In addition, when performing classic aperture synthesis without performing physical beam forming at the time of transmission, the transmission delay is multiplied at the same timing as the reception delay in the digital wave signal processing.

  From the above, in the present invention, the receiving unit 32 always has an independent analog or digital delay, receiver 32a, AD converter 32b, and memory (or storage device or storage medium) in each reception channel. 32c, and if necessary, level adjustment by analog amplification or attenuation, an analog filter, and other analog arithmetic devices. That is, in the apparatus of the present invention, when this digital delay is performed by the reception delay, an error that depends on the clock frequency does not occur as in the case of the analog delay unless a delay for beam forming is applied.

  In other words, an error that depends on the clock frequency always occurs in the digital delay of transmission, so it is necessary to reduce the error by using a high clock frequency at a high cost, but that is not necessary in the digital delay of reception. . If a digital delay is used for the reception delay, the accuracy is not lowered and the freedom of setting the delay pattern is high. If an analog delay is used for the transmission delay, the accuracy is high and the clock frequency can be lowered. The analog delay can be changed in an analog manner or can be made digitally programmable. However, the analog delay has a lower degree of freedom than the digital delay, and when the cost is reduced, the delay pattern mounted as an analog circuit may be used by switching or may be used by replacing it with an appropriate one. When a high degree of freedom is required for setting the transmission delay pattern, it is necessary to operate the digital delay with a high clock.

  Hereinafter, a coherent signal generated by the beam forming itself of the present invention is referred to as an image signal. The reception effective aperture elements and their positions are controlled in the same manner as the transmission effective aperture elements (described later). The digital beam forming is not always performed every time a reception signal for one frame is stored. For example, the digital beam forming is input from the input device 40 or the like as appropriate, for example, an effective aperture width or a predetermined number other than that. The number of hardware channels, such as the number of hardware signals that are set, may be set at every timing when a number of received signals that may be programmable parameters are stored (there are various input means as described above). In addition, an image signal generated by partial beamforming may be combined into an image signal of one frame.

  In that case, the received signals processed at consecutive positions in the scanning direction may be overlapped. When these received signals are combined, simple overlaying (overlapping in the frequency domain) is performed. May be combined and inverse Fourier transformed), suitably weighted and superimposed, or simply connected. The number of stored reception signals can be confirmed in hardware or a control program by counting a trigger signal (command signal received from the control unit 34) for receiving the reception signal. The command signal for starting the digital wave signal processing of one frame generated by the control unit 34 for each frame can be confirmed in the same manner, and the image signal of one frame is appropriately generated continuously.

  The maximum frame rate that can be achieved depends on the form of beam forming to be performed, and is basically determined by the wave propagation speed. However, in actual applications, it is the time required to digitally calculate one frame of image signal. Determined. Therefore, it is useful to perform the process of generating the image signal partially by parallel processing. In addition, as described above, the multi-directional aperture synthesis developed in the past by the first inventor of the present application, generating a reception beam in a plurality of positions and a reception beam in a plurality of directions for one transmission beam, It is useful to perform multi-focusing, and it is useful to perform parallel processing in order to implement them at high speed. In any case, on the basis of performing the above transmission and reception, a reception signal for beam forming for one frame or a part thereof may be stored, and digital wave signal processing in the present invention described in detail later may be performed. In addition, when the image signal cannot be generated in real time, the frame rate may be lowered or may be processed offline.

  The reception apodization weights the reception signal in the reception channel of each aperture element and may be variable with respect to the range direction. It is not impossible to make it variable in analog, but it is easy to make it digitally variable. In a normal receiving unit, when performing phasing addition, it is carried out at each position, each range position, etc. and is often variable, but in the apparatus according to the present invention, it is carried out by the digital signal processing unit 33. become. On the other hand, although it is rare that non-variable apodization is performed, in that case, apodization is performed when performing level adjustment by analog amplification or attenuation on the reception signal generated by the aperture element.

  Although it has a different meaning from apodization, at least level calibration may be performed based on calibration data of the conversion efficiency (conversion capability) of the driving signal of the aperture element into a wave, and apodization is also performed at the same time as level calibration. May be. The processing may be aimed at, or the dynamic range of the waveform of the received analog signal may be nonlinearly expanded or compressed, and other analog devices such as nonlinear elements are used in each reception channel. Sometimes. The analog devices used, including those amplifiers and the like, may be programmable, and the setting method may take various forms. Like other parameters, it may be set directly using various input devices. Usually, the delay and the apodization are implemented in the receiving unit 32 in the same or different hierarchical levels in the same or different forms, but usually in a phasing adder, in the present invention. Can be implemented in the digital signal processing unit 33 with a high degree of freedom.

  The reception channel of each aperture element in the reception effective aperture is switched through a switching device such as a shift register or a multiplexer, and the region of interest may be scanned while performing beam forming using the effective aperture at another position. Further, the delay value of the delay element may be variable, and the delay pattern (delay element group) may be switched. Further, steering in a plurality of directions may be performed at one effective opening, and steering may be performed in a plurality of directions while changing the opening position and effective opening width as appropriate. The access time may be shortened by saving the device or the storage medium. The effect of storing frequently used data in a small memory that is easy to read and write as appropriate is also great.

  In the present invention, the saving and the shortening of the access time are significant. The apodization element group constituting the apodization pattern may be switched. The beam shape may be adjusted depending on the opening position, the range direction, and the steering direction. In detail, it means that the receiving element with zero apodization value is not active but is off, and the apodization also serves as a switch for the effective element and can determine the effective aperture width (apodization in the direction of the aperture element array). If the function is a rectangular window, the switch is on. If it is not a constant value, the switch is on). Therefore, the apodization element is of the same level as the switch.

  In addition, when the delay pattern or the apodization pattern includes a plurality of patterns or is programmable, propagation is performed in the digital signal processing unit 33 in the apparatus main body 30 based on the response from the transmission target or the result of beam forming. Wave attenuation and scattering (forward scattering, backscattering, etc.), transmission, reflection, refraction, or sound velocity frequency dispersion and spatial distribution in the process medium are calculated and transmitted from each aperture and received at each aperture Delay, intensity, beam or wavefront steering direction, or apodization pattern may be optimized.

  In classical aperture plane synthesis, all receiving elements may have a receiving channel including the receiver 32a. In general, aperture synthesis is performed simultaneously with reception apodization in the phasing adder. In the present invention, aperture synthesis may be performed simultaneously with reception apodization in the digital signal processing unit 33.

  In addition, the ultrasonic frequency and bandwidth as parameters in the transmission unit 31 and the reception unit 32, code, delay pattern, apodization pattern, analog device for signal processing, effective aperture width, focus position, steering direction, and The number of transmissions and receptions required for performing beamforming is transmitted to each functional device in the unit through various media such as a CD-ROM, DVD, floppy (registered trademark) disk, or MO. Sometimes installed.

  In some cases, the program can be started to select them interactively from the input device 40, or numerical values can be directly input, they can be selected on the operation panel of the input device 40, or other files in which data is recorded can be selected. There are various cases, such as when reading and setting. It is also possible to define them using a dip switch or the like. It may be due to unit replacement or switching. In addition, when a measurement target is selected or a transducer to be used is attached to the apparatus, the apparatus may be recognized and automatically operate under recommended parameters. Subsequent adjustments are possible. In addition, if a functional device of a normal receiving unit is mounted, an image image obtained by using the apparatus of the present invention and an image image obtained by processing including interpolation interpolation through normal phasing addition as appropriate. Can be compared.

<Input device>
The input device 40 is used, for example, for setting various parameter values as described above. Examples of the input device 40 include, but are not limited to, a keyboard, a mouse, a button, a panel switch, a touch command screen, a foot switch, or a trackball. Install or upgrade the operating system (OS) and device software from general-purpose memory, USB memory, hard disk, flexible disk, CD-ROM, DVD-ROM, floppy disk, or MO storage media And various parameter values may be set or updated. The input device 40 includes various devices that can read data from the storage medium, or the input device 40 includes an interface, and various devices are mounted and used as necessary.

  The input device 40 is used not only for setting parameters of various operation modes of the device according to the present embodiment, but also for controlling and switching the operation modes. When the operator is a human, the input device 40 can be a so-called man-machine interface, but is not necessarily controlled by a human. As described above, parameter values, data, or control signals are received from other devices through various standards and connectors, or are received through wired or wireless communication (that is, communication devices having at least a reception function). The effect is obtained, and the present invention is not limited to the above example. A dedicated or regular network may be used.

  The input data is stored in a memory, a storage device, or a storage medium inside or outside the apparatus, and functional devices in the apparatus operate with reference to the stored data. Alternatively, when the functional device in the apparatus is equipped with a dedicated memory, data is written to it and the operation setting is determined by software, updated, or hardware is set, Or it may be changed. In some cases, the calculation function in the apparatus operates, and optimized setting parameters are calculated and used based on the input data, sometimes taking into account the resources of the apparatus. The operating mode may be determined by a command. In addition, the wave to be measured (wave type and characteristics, intensity, frequency, bandwidth, sign, etc.), the object to be propagated and the medium (propagation speed, physical property value related to the wave, attenuation, forward scattering, backscattering, Additional information regarding transmission, reflection, refraction, etc., or their frequency dispersion, etc.) may be provided and the received signal may be appropriately analog or digitally processed.

<Output device>
A typical output device 50 is a display device. The display device not only displays the generated image signal, but also displays various results measured based on the image signal as numerical values, images, and the like. Used to display. The image signal is converted (scan converted) into an image display or moving image or still image format by calculation processing, but a graphic accelerator may be used. A luminance image (gray image) or a color image may be displayed, and the meaning represented by the luminance or color may be displayed on a scale (bar) or logo. In addition, the result may be displayed as a bird's eye view or a graph, and the method of displaying the result is not limited to them.

  When the result is displayed, various parameter values and patterns (names) when the operation mode is operating may be appropriately displayed as a logo or a character together with each operation mode. In addition, supplementary information and various data related to the measurement target input from the operator or another device may be displayed. In addition, the display device may be used to display a GUI (Graphical User Interface) used when setting each parameter value or pattern using the input device 40, and uses a touch command screen. This is also used when an arbitrary position or range of an image to be rendered is designated and displayed in an enlarged manner or various numerical values are displayed, and may serve as one end of the input device 40.

  As the display device, various devices such as a device using a CRT, a liquid crystal, or an LED are used. However, the display device is not limited to such as a dedicated three-dimensional display device. Also, the output data is not necessarily used by human being directly interpreted or interpreted, but the device body (computer) understands the output data based on predetermined calibration data and calculation and displays the result. In some cases (for example, understanding the composition and structure of the measurement object from the spectrum analysis of the received signal), the output data is output to another device and interpreted by the other device, and the same device (for example, a robot). Or another device may apply the output data.

  One device may receive a plurality of types of waves to generate image signals, and data mining and fusion may be performed, or another device may be used to perform that type of processing. is there. The characteristics (intensity, frequency, bandwidth, code, etc.) of the generated image signal may be analyzed. As described above, data obtained by the apparatus according to the present embodiment may be used in another apparatus, and a communication device having at least a transmission function may be one of the output apparatuses 50 in practice. A dedicated or regular network may be used.

<Storage device>
The generated image signal and various results (numerical values, images, etc.) measured based on the image signal are stored in a memory, a storage device, or a storage medium inside or outside the device that also becomes the output device 50. Here, they are distinguished from display devices as “storage devices”. An external storage device 60 is also shown in FIG. When storing an image signal, an operation mode, a setting parameter value, supplementary information about an object input from an operator or another device, or various data may be stored together with the image signal. As the storage device, general-purpose or special memory, USB memory, hard disk, flexible disk, CD-R (W), DVD-R (W), video recorder, image data capturing device, or the like is used. The device is not limited to them. The storage device is appropriately used in accordance with the application, including the amount of data to be stored and the time for writing and reading.

  Although image signals and other data stored in the past may be read out from the storage device and played back, the main point is that the storage device is important for storing the OS, device software, or setting parameters. It is. Each functional device may have a dedicated storage device. A removable storage device may be used in other devices.

  The apparatus main body 30 reads out the image signal stored in the storage device, performs high-order digital signal processing, and re-synthesizes the image signal (frequency modulation or broadening by linear processing or non-linear processing, multi-focus, etc.), Perform various measurements such as image processing of image signals (super-resolution, enhancement, smoothing, separation, extraction, CG conversion, etc.), displacement and deformation of the object, and other various temporal changes, etc. Measurement results may be output and displayed on the display device.

  The stored measurement results include wave attenuation and scattering (forward scattering, backscattering, etc.), transmission, reflection, and refraction, which are read out and optimized for various parameters that generate image signals. In some cases, it is used for storage and stored in a storage device. The optimization is performed by a calculation function provided in the control unit 34 or the digital signal processing unit 33.

<Control unit>
The control unit 34 controls the operation of the entire apparatus. The control unit 34 is composed of various computers, a dedicated digital circuit, and the like, and may also serve as the digital signal processing unit 33. Basically, the control unit 34 performs wave transmission / reception and wave digital signal processing based on various control programs and various data read from the storage device in response to various requests input via the input device 40. The transmission unit 31, the reception unit 32, and the digital signal processing unit 33 are controlled so as to generate an image signal.

  When the control unit 34 is configured by a dedicated digital circuit, the parameter may be variable, but there may be a case where only a fixed operation can be realized including switching the operation by switching. When a computer is used as the control unit 34, the degree of freedom is high, including when upgrading. The basics of the control unit 34 are the number of transmission and reception aperture elements (the number of each channel), the number of beams to be generated, the number of frames (some operations will continue unless specified and stopped), the frame rate, etc. In response to this, the transmission unit 31 and the reception unit 32 are provided with repetition frequency, transmission / reception position information, and the like to perform scanning control and image signal generation control. Also controls. In addition, various interfaces are provided, and various devices may be used in conjunction with each other.

  The apparatus according to the present embodiment may be used as one of devices such as a general network and a sensor network, and may be controlled by a control device of the network system, and control for controlling the network device. It may be used as a device or a control device that controls a locally configured network. An interface for this purpose may be provided.

<Beam forming method>
Next, useful high-speed through digital Fourier transform in the case of using a plurality of transmission / reception aperture elements (including those in the form of an array) implemented in the digital signal processing unit 33 of the apparatus main body 30 shown in FIG. A digital beam forming method will be described. In digital signal processing, intermediate data generated in the calculation process or data to be used repeatedly may be stored in a storage device or a built-in memory as appropriate, and when generating a plurality of image signals in the same phase. However, the storage device is used efficiently. Small-sized memory may come in handy.

  The generated image signal may be displayed as a moving image or a still image on the output device 50 such as a display device, or may be stored in the external storage device 60 using a recording medium such as a hard disk. In the case where the digital signal processing unit 33 is a computer, various languages can be used and the assembler is useful. In particular, when the computer is operated under a high-level language program such as C language or Fortran. In some cases, optimization and parallel processing are performed at the time of compilation to realize high-speed computation. A general-purpose one such as Matlab, various control software, a graphic interface, or the like may be used, or a special one may be used.

  In the following, as an example, a beam forming method used in the apparatus of the present invention will be described through the case where the wave is an ultrasonic wave. The beam forming methods that can be used in the present embodiment are the following methods (1) to (7). In the method (7), in addition to various beam forming methods, the digital signal processing unit 33 generates the beam forming method. Disclose representative observation data.

  Method (1) is an interpolation that has been required so far in performing wave number matching in Fourier space in plane beam transmission and / or reception beamforming at the time of reception including the case where the transmission direction is deflected (steered). This method does not require approximation processing. Method (1) is an invention in which wave number matching in the depth direction and the transverse direction is performed by dividing a complex exponential function related to the cosine and sine of the deflection angle and multiplying the received signal by the wave number matching in the case of performing deflection. In addition, the measurement results are improved in accuracy as in the case of the classical monostatic type aperture plane synthesis. Furthermore, as a method (2), high-speed digital processing of deflection dynamic focusing by monostatic aperture surface synthesis is disclosed.

  Furthermore, as a method (3), a high-speed digital process of multistatic aperture surface synthesis is disclosed. In the digital monostatic type aperture surface synthesis that performs deflection, the centroid (center) or instantaneous frequency of the multidimensional spectrum of the generated image signal is ideally expressed using the deflection angle and the carrier frequency (described later). As in the method (1), the wave number matching is performed so that the wave vector becomes the component of the carrier frequency multiplied by the sine and cosine of the deflection angle. Can be realized with accuracy. On the other hand, multi-static aperture surface synthesis generates echo data frames including echo signals received at the same position of a plurality of reception positions with respect to the transmission position, as many as the number of receiving elements, and each echo is generated in the frequency domain. The data frame is subjected to the above-mentioned monostatic type digital aperture synthesis processing, and the result of superimposing these processing results is subjected to inverse Fourier transform to achieve high accuracy. As a result, in the method (3), echo data can be generated by digital aperture plane synthesis processing equal to the number of channels of the reception aperture, and so-called low spatial resolution image signal frames are generated and superimposed to generate a high spatial resolution image signal. This is much faster than the conventional DAS (Delay and Summation) method for generating a frame.

  Incidentally, in the DAS method, phasing is realized by delaying the received signal at high speed with interpolation approximation processing in the spatial domain, and by delaying in the frequency domain with high accuracy ( The first inventor of the present application has a past performance), and the received signals are summed in the spatial domain. The former has high speed but low accuracy, and the latter has high accuracy but extremely low speed.

  As a method (4), a method of performing digital dynamic focus reception at the time of fixed transmission focus with high accuracy based on the beam forming of the method (1) and the method (3) is disclosed. As method (5), echo data transmitted / received in the polar coordinate system is processed through Jacobi calculation for high precision display without interpolation approximation processing, for convex, sector scan, or IVUS applications. Disclose that echo data can be generated directly in the Cartesian coordinate system of the system.

  Further, as a method (6), it is disclosed that migration processing can be performed with high accuracy and high speed without performing interpolation approximation processing in the same manner using the present invention. All the beam forming processes of the method (1) to the method (5) can be performed based on the migration process. Finally, as a method (7), an application based on these beamforming is disclosed. With these, it is possible to demonstrate that any beam forming based on focusing and steering can be performed.

Method (1): Beam forming for plane wave transmission and / or plane wave reception (i) Echo signal (image signal) during plane wave transmission
FIG. 5 is a schematic diagram of transmission of a deflected plane wave. Plane wave transmission is a method of emitting a plane wave by radiating ultrasonic waves simultaneously from all elements in a linear array type transducer. When the wave number is k and a plane wave of the wave vector represented by the equation (0) is transmitted (x is the scanning direction, y is the depth direction), the position of the reception effective aperture element array is set to zero in the y coordinate. And the sound pressure field at the position (x, y) is expressed by the equation (1).

Here, A (k) is the frequency spectrum of the transmitted pulse and has the relationship of equation (2).

When there is a scatterer having a reflection coefficient f (x, y _i ) at a depth y = y _i , the echo signal from this scatterer is expressed by Equation (3).
The angular spectrum of this equation is expressed by equation (4).

If the frequency response of the probe is T (k), the angular spectrum at the aperture (y = 0) of the echo signal from depth y = y _i is expressed by equation (5) based on the principle of angular spectrum. Is done.

Therefore, by adding the angular spectra from the respective depths, the angular spectrum of the echo signal represented by equation (6) is obtained.

Therefore, by performing wave number matching as Expression (7) and Expression (8), an echo signal (image signal) can be expressed as Expression (9) by this inverse Fourier transform.

  Considering transmission and reception in reverse, arbitrary transmission beamforming (for example, deflection plane wave, deflected fixed focusing beam, undeflected wave or beam, etc.) was performed on the measurement object. In this case, it is possible to realize a situation in which a wave coming from the measurement object is received as a plane wave having a deflection angle θ. This idea has not been disclosed so far. In this way, it is possible to receive a wave at the same or different steering angle θ (zero or non-zero) when transmitting an arbitrary beam or arbitrary wave with an arbitrary steering angle (zero or non-zero). . Furthermore, an arbitrary wave source, an arbitrary transmit effective aperture array (for example, an aperture having the same shape as the receive effective aperture array or having an aperture in an arbitrary direction different from the receive effective aperture array, or existing at a different position) Alternatively, reception beam forming can be performed in a coordinate system defined by the reception aperture for any wave transmitted from the same physical aperture but from an effective aperture at a different position.

Based on the above theory, the calculation method disclosed by J.-y. Lu et al. (Non-Patent Documents 3 and 4) first performs fast two-dimensional Fourier transform on the received signal with respect to time and space, and R (k _x , k) is calculated, and then wave number matching is performed using equation (7) to perform high-speed two-dimensional inverse Fourier transform. Wave number matching is performed through linear interpolation approximation or approximation with the nearest neighbor data itself, and it is required to oversample the received signal in order to obtain accuracy.

(Ii) Calculation procedure of echo signal (image signal) at the time of transmission and / or reception of plane wave according to the present invention A case where a plane wave having a deflection angle θ is transmitted and / or received will be described below. In the present invention, wave number matching is performed in the lateral direction by multiplying the received signal by a complex exponential function (formula (9a)) before the Fourier transform of the received signal in space (lateral direction), and in the depth y direction. Is multiplied by the complex exponential function (formula (9c)) at the same time as the complex exponential function (formula (9b)) excluding the above-described horizontal matching processing is applied to have resolution in the depth y direction. . Of course, the deflection angle θ can be used not only at non-zero degrees but also at zero degrees. This process is not disclosed in prior art documents.

FIG. 6 is a flowchart showing digital signal processing during deflection plane wave transmission. The calculation procedure is as follows. First, in step S11, as shown in Expression (10), the received signal is Fourier transformed with respect to time t (FFT is good).
However, when ω is an angular frequency (angular frequency) and c is the speed of sound, the wave number k = ω / c. Thus, an analysis signal is obtained. Here, in accordance with the above description, a process is shown in which the sign of the core of the complex exponential function is positive as the Fourier transform, but the sign of the core of the complex exponential function is calculated as negative as in the normal Fourier transform. It is also possible. In any case, in the inverse Fourier transform calculated later, a complex exponential function whose sign is opposite to that at the time of the Fourier transform is used. The same applies to the other methods (2) to (7).

Next, in step S12, it performs a matching process with respect to the wave number _{k x} for deflecting, multiplied by equation (11) into equation (10), in step S13, Fourier transform (FFT regard lateral x received signal By doing so, equation (12) is obtained. For the calculation of the product of the result (10) of the fast Fourier transform with respect to time t and the complex exponential function (11), a dedicated fast Fourier transform that directly generates the calculation result is useful.
Incidentally, the result of equation (12) can also be obtained by direct calculation.

The received signal is decomposed into plane wave components by the two Fourier transforms. As described above, the angular spectrum that each plane wave creates at an arbitrary depth y is obtained by multiplying the phase by multiplying the equation (13).

Furthermore, in step S14, the matching process is simultaneously performed on the wave number ky by simultaneously multiplying the equation (14).

In step S15, an angular spectrum of each depth y is calculated. That is, the equation (16) is obtained by multiplying the equation (15).

The sound pressure field generated by each plane wave component at the depth y is obtained as an equation (17) by performing an inverse Fourier transform (IFFT) on the lateral direction x.
An image signal is obtained by adding a plurality of wave number k components (or frequency components).

Here, the integration of the wave number k (or frequency) and the spatial frequency kx can be changed in order. Therefore, adding the wavenumber k component of the angular spectrum in step S16, even if the inverse Fourier transform with respect to the transverse direction of the wave number _{k x} a (IFFT) in step S17, the image signal is obtained in step S18. In this case, calculation can be performed by one inverse Fourier transform, and the calculation is faster. The same applies to the other methods (1) to (6). The wave number matching for deflection is performed by the equations (11) and (14). Unlike the method of performing wave number matching through interpolation approximation in the frequency domain (Non-Patent Documents 3 and 4), the present invention does not perform approximation processing, and therefore can calculate with high accuracy. Physically and mathematically, wave number matching can be performed at the first Fourier transform, and wave number matching can be performed at the last inverse Fourier transform. The same applies to the other methods (1) to (6).

Also, using a two-dimensional aperture element array, an arbitrary wave is transmitted from a wave source located in an arbitrary direction toward the measurement object, and a wave arriving from the measurement object is received as a plane wave having a deflection angle θ. When performing three-dimensional wave digital signal processing, for example, a Cartesian orthogonal coordinate system (x , y, z), when the zero-degree or non-zero-degree deflection angle formed by the plane wave receiving direction and the axial direction is expressed by using the elevation angle θ and the azimuth angle φ , the Fourier transform is transverse to the depth y direction. A three-dimensional Fourier transform is performed with respect to the directions x and z, and the following processing is performed as in the case of performing the two-dimensional wave digital signal processing.

First, wave number matching in the horizontal direction x and z is performed by multiplying the received signal Fourier-transformed in the axial direction y by the complex exponential function (C21) expressed using the wave number k and imaginary unit i of the wave,
Furthermore, the product can be implemented on the angular spectrum obtained by Fourier transform with respect to the lateral directions x and z so as to have a resolution with respect to the axial direction y, excluding the effect of wave number matching performed in the lateral directions x and z. The wave number matching in the axial direction is performed by multiplying the complex exponential function (C22) at the same time as the complex exponential function (C23), where the transverse wavenumber is represented by k _x and k _z ,
By performing wave number matching without performing interpolation approximation processing, an image signal can be directly generated in a Cartesian coordinate system. That is, the sound pressure field generated by each plane wave component at the depth y is subjected to two-dimensional inverse Fourier transform (IFFT) with respect to the lateral directions x and z, and a plurality of wave number k components (or frequency components) are added. Thus, an image signal is obtained. Of course, it can also be used when the deflection angle is zero degrees (that is, the elevation angle θ and the azimuth angle φ are zero degrees).

  In the above calculation, only signal components within the band determined by the transmission signal or within the band determined in consideration of the SN ratio of the reception signal are to be calculated. For example, when generating an analysis signal based on Expression (10), only a signal within a necessary band may be generated and stored (corresponding to downsampling). In the method or apparatus of the present invention, interpolation approximation processing is not performed when performing wave number matching, but by oversampling the echo signal in the depth direction or in the lateral direction, an effect that is robust against mixed noise is obtained. is there. The same applies to the other methods (1) to (6).

  Further, in the formulas (13) to (15), by determining the position coordinate and range in the depth y direction to be calculated, the interval between the coordinates, etc., the arbitrary depth position or the range in the arbitrary depth direction, or It is possible to generate an image signal having an arbitrary interval or an arbitrary density in the depth direction without performing an interpolation approximation process. Further, in the inverse Fourier transform in the horizontal direction of the equation (17), by determining the position coordinates and the range in the horizontal x direction to be calculated (if necessary, the complex exponent which is the past invention of the first inventor of the present application) Analog space shifting by phase rotation using function multiplication), image signals in any horizontal position or any horizontal range can be generated without performing interpolation approximation processing. In the inverse Fourier transform, the band is narrowed in the horizontal direction except for the frequency coordinates of the high frequency band (spatial density is reduced), or is widened in the horizontal direction by zero padding of the angular spectrum (spatial density is high). ), It is possible to generate image signals having arbitrary intervals and arbitrary densities in the horizontal direction without performing interpolation approximation.

  In this way, an image signal can be generated at any desired position, range, interval, and density. That is, the image signal can be generated at an interval shorter than the sampling interval of the received signal and at a pitch shorter than the interval between the receiving aperture elements. It is also possible to coarsen the image signal spacing in each direction (however, the Nyquist theorem must be satisfied). The same applies to the other methods (1) to (6).

  In convex transducers, sector scans, or IVUS, when transmitting or receiving in the radius r direction of polar coordinates to generate a wide wave (cylindrical wave) in the angle θ direction (FIG. 7), or in other aperture shapes, When performing the same beam forming (cylindrical wave) using a virtual source installed at the rear (Fig. 8), in the above method, the Cartesian coordinates (x, y) are replaced with polar coordinates (r, θ) and processing is performed. The image signal can be generated at polar coordinates (r, θ). The same applies to spherical waves in a spherical coordinate system.

  FIG. 7 is a schematic diagram of a case where a wide wave in the direction of the angle θ in polar coordinates (r, θ) is transmitted or received in the direction of the radius r (cylindrical wave transmission). 7A shows a cylindrical wave transmission using a convex aperture element array, and FIG. 7B shows a cylindrical wave transmission using a sector type aperture element array. (C) shows a cylindrical wave transmission using an IVUS (circular type) aperture element array.

  FIG. 8 shows a case where a wide wave is transmitted in the direction of the angle r of the polar coordinate system (r, θ) in the radius r direction using a virtual source installed behind a physical aperture having an arbitrary aperture shape (cylindrical wave transmission). ). 8A shows a cylindrical wave transmission using a linear aperture element array, and FIG. 8B shows a cylindrical wave transmission using a convex aperture element array. (C) has shown the cylindrical wave transmission using the other arbitrary aperture element array.

  In the case of transmission focus, there is a report in Non-Patent Document 6, and similarly, a result is obtained in polar coordinates (r, θ). For example, there is an effect that a wide FOV can be obtained. As a feature different from Non-Patent Document 6, one feature of the present invention is that the present method (1) is used to generate a steering beam having a steering angle even in the coordinate positions of these polar coordinate systems (r, θ). The same applies when the following methods (2) to (4) and (6) are used, in which the Cartesian coordinates (x, y) are replaced with polar coordinates (r, θ). What is necessary is just to process. However, when performing these beam forming operations, it is necessary to perform interpolation processing to obtain signal values at the coordinate positions of the Cartesian coordinate system of the display system, and use phase rotation by product of complex exponential functions in the frequency domain. The exact interpolation processing that has been performed is performed over time, or the interpolation approximation processing is performed as a short-time processing with an approximation error. The same applies to spherical coordinates.

  In these cases where beam forming is performed in the polar coordinate system, displacement measurement can also be performed. For example, a displacement component in the radius r direction or the angle θ direction can be measured, or the displacement component in both directions can be measured. A displacement vector can be measured. However, in order to obtain the measurement result at the coordinate position of the Cartesian coordinate system of the display system after measurement, it is necessary to perform interpolation processing. The exact interpolation process used is performed over time, or the interpolation approximation process is performed as a short-time process with an approximation error. The same applies to the spherical coordinate system.

  From the result of displacement measurement, strain, strain velocity (tensor), velocity (vector), acceleration (vector) are obtained by partial differential processing using a differential filter. Furthermore, mechanical characteristics (for example, bulk modulus, The shear modulus, other elastic modulus tensors of anisotropic media, etc.), temperature, etc. may be obtained through computation. When interpolation approximation is performed, it is often possible to shorten the calculation time by performing approximation processing and performing the calculation in the Cartesian coordinate system. However, calculation is performed in the polar coordinate system, and the result is obtained by interpolation approximation. Display, and the propagation of error can be reduced. That is, the error that occurs in the process after displacement measurement is only interpolation approximation when obtaining the last display data (a plurality of display data may be obtained from the same displacement data).

On the other hand, similarly, in a convex transducer, sector scan, or IVUS, a wide wave in the direction of angle θ in polar coordinates (r, θ) is transmitted or received in the direction of radius r (cylindrical wave) (FIG. 7). Then, using a virtual source installed behind a physical aperture of an arbitrary aperture shape, a wide wave in the direction of the angle θ of the same polar coordinate system (r, θ) as in FIG. In this case (FIG. 8), the method of directly generating an image signal in Cartesian coordinates will be described as methods (5-1) and (5-1 ′), respectively. In these cases, echo signal imaging, displacement measurement, and the like can be performed consistently in the same Cartesian coordinate system. The same applies to the polar coordinate system.
Further, in the present methods (1) to (7), transmission, reception, or both apodization processes for a received signal can be performed at various timings because they are linear processes. That is, it can be performed in hardware at the time of reception, or can be performed at various timings in software after reception.

  As a matter of course, when beam forming is performed by receiving a transmitted wave instead of an echo signal, the coordinate y is half of the round trip distance (expressed as ct / 2 using the propagation time t). Instead, it is the distance (ct) from the aperture element in the coordinate system determined by the reception aperture element array.

Next, a case where aperture surface synthesis is performed will be described. There are monostatic type and multistatic type for aperture plane synthesis.
Method (2): Monostatic Type Opening Surface Synthesis FIG. 9 is a schematic diagram of monostatic type opening surface synthesis. In the monostatic type aperture plane synthesis, an ultrasonic wave is emitted from one element of the array, and an echo is received by the element itself. Also in aperture synthesis, echo signals (image signals) can be calculated by performing wave number matching according to the procedure of FIG.

In monostatic aperture synthesis, since transmission and reception are performed by the same element, the propagation path of sound to the scatterer during transmission and the propagation path of reflected sound from the scatterer during reception are the same. Therefore, in the Cartesian Cartesian coordinate system in which the position of the reception effective aperture element array is set to zero in the axial direction y-coordinate, when steering is not performed (θ is zero degree), the wave number k is doubled as shown in Expression (18a). (S = 2, the same applies hereinafter), and matching of the wave numbers represented by Expression (7) and Expression (8) is performed. In the case of a transmitted wave, k is used instead of wave number 2k (s = 1, the same applies hereinafter).

When the steering angle θ is non-zero, the wave number with respect to the wave vector (0, k ₀ ) having the wave number k ₀ (= ω ₀ / c) expressed using the carrier frequency ω ₀ of the ultrasonic signal. Beam forming is performed to shift the spectrum to generate an image signal having the vector (sk ₀ sin θ, sk ₀ cos θ) as the centroid (center) or instantaneous frequency of the multidimensional spectrum (see FIG. 10). That is, the wave number matching represented by Expression (18b) is performed in Expression (7) and Expression (8).

Signal processing is performed in the same manner as in the method (1), and in particular, wave number matching is performed by using ultrasonic waves instead of the complex exponential function (equation (9a)) in the previous stage of Fourier transforming the received signal with respect to space (lateral direction) Multiplying the complex exponential function (equation (19a)) expressed by using the carrier frequency ω _{0 of the} signal, first, it is carried out in the horizontal direction, and with respect to the depth y direction, in order to have resolution in the depth y direction, At the same time as the complex exponential function (formula (9b)) is multiplied by the complex exponential function (formula (19b)) excluding the horizontal matching process (formula (19a)), the complex exponential function (formula (9c)) Instead, a complex exponential function (formula (19c)) is multiplied. Of course, it can also be used when the deflection angle is zero. This process is not disclosed in prior art documents.

Further, for example, in the echo method (reflection method), the deflection angles of the transmission beam and the reception beam may be different. In this case, if the deflection angles of the transmission beam and the reception beam are θ _t and θ _r , In Expressions (7) and (8), wave number matching represented by Expression (18c) is performed under s = 2.

The signal processing is performed in the same manner as in the case where the deflection angles of the transmission beam and the reception beam are equal to each other. In particular, the wave number matching is performed in a complex exponential function (formula) in a stage before Fourier-transforming the reception signal with respect to space (lateral direction). (19a)) is multiplied by the complex exponential function (equation (19d)) expressed using the carrier frequency ω ₀ of the ultrasonic signal, and is first performed in the lateral direction, and the depth y direction is the depth. In order to have a resolution in the y direction, a complex exponential function (formula (19e)) excluding the horizontal matching process (formula (19d)) is multiplied instead of the complex exponential function (formula (19b)) and at the same time complex This is performed by multiplying the complex exponential function (formula (19f)) instead of the exponential function (formula (19c)). Of course, it can also be used when the deflection angles θ _t and θ _r are zero degrees. This process is also not disclosed in the prior art documents.

Further, in the case of performing three-dimensional wave digital signal processing using a two-dimensional aperture element array, for example, the axial direction y determined by the aperture direction of a flat receive aperture element array (the y of the position of the receive effective aperture element array) In Cartesian Cartesian coordinate system (x, y, z) using the coordinates of x and z in the transverse direction orthogonal to this) and zero or non-zero deflection formed by the direction and axis of the generated beam In the case where the angle is expressed using the elevation angle θ and the azimuth angle φ , the Fourier transform performs a three-dimensional Fourier transform on the depth y direction and the lateral directions x and z (the wave numbers in the axial direction y and the lateral directions x and z are calculated). The wave number regions (k _x , k _y , k _z ) are considered as k _y , k _x , and k _z , respectively. Similarly to the case of performing the two-dimensional wave digital signal processing, the following processing is performed. The

First, with respect to a wave vector (0, k ₀ , 0 ) having a wave number k ₀ (= ω ₀ / c) expressed using the wave carrier frequency ω ₀ , the wave vector (sk ₀ sinθcos φ , sk ₀ cosθ , sk ₀ sinθsin φ ) is the centroid (center) or instantaneous frequency of the multidimensional spectrum, and the received signal is Fourier transformed with respect to the axial direction y to perform dynamic transmission and reception with spectral shifting to generate an image signal. A parameter s having a value of 2 when the y-coordinate of the transmission aperture element is zero and a value of 1 when the y-coordinate of the transmission aperture element is non-zero, and the barycentric (center) frequency k ₀ , And by multiplying the complex exponential function (C41) expressed using the imaginary unit i, wave number matching in the horizontal directions x and z is performed,
Further, the product can be applied to an angular spectrum obtained by Fourier transform with respect to the lateral directions x and z so as to have a resolution with respect to the axial direction y, excluding the effect of wave number matching performed in the lateral directions x and z. Multiplying the exponential function (C42) and simultaneously performing the complex exponential function (C43) to perform wave number matching in the axial direction,
By performing wave number matching without performing interpolation approximation processing, an image signal can be directly generated in a Cartesian coordinate system. That is, the sound pressure field generated by each plane wave component at the depth y is subjected to two-dimensional inverse Fourier transform (IFFT) with respect to the lateral directions x and z, and an image signal is obtained by adding a plurality of frequency k components. . Of course, it can also be calculated when the deflection angle is zero degrees (that is, the elevation angle θ and the azimuth angle φ are zero degrees).

Further, for example, in the echo method (reflection method), the deflection angles of the transmission beam and the reception beam may be different. In this case, the deflection angles are (elevation angle, azimuth angle) = (θ _t , φ _t ) And (θ _r , φ _r ), the signal processing is performed in the same manner as in the case where the deflection angles of the transmission beam and the reception beam are equal under s = 2, The wave number matching is a complex exponential function (expressed by using the carrier frequency ω ₀ of the ultrasonic signal instead of the complex exponential function (formula (C41)) before the Fourier transform of the received signal with respect to space (lateral direction). Multiply (D41)) first, in the horizontal direction, with respect to the depth y direction, in order to have resolution in the depth y direction, the horizontal matching instead of the complex exponential function (formula (C42)) Complex exponent excluding processing (formula (D41)) Simultaneously multiplying the number (equation (D42)), it is performed by multiplying the complex exponential function instead of complex exponential function (Equation (C43)) (formula (D43)). Of course, it can also be used when the deflection angles of the transmission beam and the reception beam are zero degrees (that is, θ _t , φ _t , θ _r , and φ _r are zero degrees). This process is also not disclosed in the prior art documents.

  Aperture synthesis can generate arbitrary beamforming using echo signals collected for aperture synthesis (not only in the monostatic method of this method (2) but also in the multistatic method of method (3)). However, an image signal can be generated even if the processing described in the methods (1) and (4) to (7) is performed on the data. In the plane wave processing of the method (1), the aperture plane synthesis processing can be performed by using a code. Further, in a convex transducer, sector scan, IVUS, or the like, when a wide wave is transmitted or received (cylindrical wave) in the angle θ direction in polar coordinates (r, θ) in the radius r direction (FIG. 7), When a wide wave is transmitted in the direction of the angle θ of the polar coordinate system (r, θ) in the same polar coordinate system (r, θ) as in FIG. (Fig. 8) and echo signals collected for aperture plane synthesis in the polar coordinate system, the Cartesian coordinates (x, y) are replaced with polar coordinates (r, θ) as in method (1). The image signal can be generated in a Cartesian coordinate system (x, y) or polar coordinates (r, θ). The same applies when other transmission beamforming is performed or when they are performed in a spherical coordinate system. In addition, since apodization processing for transmission, reception, or both for the received signal is linear processing, it can be performed at various timings (hardware at the time of reception or software after reception).

Method (3): Multistatic Type Aperture Synthesis FIG. 11 is a schematic diagram of multistatic type aperture synthesis. Multistatic aperture surface synthesis is a method in which ultrasonic waves are emitted from one element of an array and echoes are received by a plurality of elements around the element. A low resolution image signal is obtained for each radiation, and a high resolution image signal is generated by superimposing a plurality of low resolution image signals obtained.

  As described above, it is a conventional method to generate a low resolution echo signal from echo signals received for each element radiation and superimpose them. On the other hand, in the present invention, a signal group composed of signals having the same transmission / reception position relationship is set as one set, and digital monostatic aperture synthesis is performed for each set, and a plurality of values are obtained by this method (3). The processing is finished by superimposing these low resolution image signals. In practice, superposition that is a linear process can be performed in the frequency domain before the inverse Fourier transform process, which is faster, and the horizontal alignment for the superposition is also superposed. In this case, the image signal can be generated without performing interpolation approximation at high speed by multiplying the complex exponential function for performing the shifting process in the horizontal direction and rotating the phase in the horizontal direction.

However, what is important is that when applying the monostatic aperture plane synthesis processing program, if the distance between the reception position and the transmission position is Δx, the converted distance y ′ of the propagation path until reception is performed at a position separated by Δx. Is calculated and used. When the deflection angle is zero degree, the conversion distance represented by the equation (20) is calculated.

  When the deflection angle is θ (including zero degree), multi-static aperture synthesis is performed to generate a beam that has been subjected to at least dynamic reception focusing (when s = 2, transmission dynamic focusing can also be realized). As a beam forming method to be performed, a wave is transmitted from each of a plurality of transmission aperture elements in a transmission effective aperture element array, and a wave arriving from a measurement object is transmitted by at least one of a plurality of reception aperture elements at different positions. Receives and generates a received signal (can be processed by the device of the present invention even if there is only one), and the transmission aperture element has a wave generated by at least reflection or backscattering in the measurement object (S = 2), or generated by at least transmission, forward scattering, or refraction in the measurement object (S = 1) of the receiving effective aperture element array having an arbitrary x coordinate without depending on the x coordinate of the receiving aperture element generating the received signal and further having a zero y coordinate. A position opposite to the reception effective aperture element array, each serving as one of the reception aperture elements, or one of a plurality of transmission aperture elements different from any of the reception aperture elements, or having a non-zero constant y coordinate Each of the plurality of transmission aperture elements in the transmission effective aperture element array in FIG.

For each received signal group obtained by arranging the received signal the distance Δx is equal in the horizontal direction coordinate between the receiving position and transmitting position, when the y coordinate of the transmission aperture element is zero, the position of the transmit aperture The distance (equation ( 20 )) of a straight line connecting the transmission aperture element, the interest point, and the reception aperture element expressed by using the y coordinate of the interest point and the distance Δx, or the transmission aperture element when the y-coordinate is nonzero, distance between Seki y coordinates and transmission aperture element of the centroid point y = Y-coordinate and the distance Δx and transmission aperture element and the point of interest and receive aperture element represented using using the above each of the image signal obtained by setting the deflection angle in the monostatic synthetic aperture corrected for lateral position in the frequency domain, the image signal without performing the interpolation approximation process by superimposing them Can produce

Also, when performing three-dimensional wave digital signal processing using a two-dimensional aperture element array, for example, an axial direction y determined by the orientation of the aperture of a flat receiving aperture element array and lateral directions x and z orthogonal thereto In a Cartesian Cartesian coordinate system using the coordinates of, the same processing can be performed, and the zero or non-zero deflection angle formed by the generated beam direction and axial direction is expressed using the elevation angle θ and the azimuth angle φ , A wave is transmitted from each of the plurality of transmission aperture elements in the transmission effective aperture element array, and a wave arriving from the measurement target is received and received by at least one of the plurality of reception aperture elements at different positions. The transmission aperture element generates a signal whose wave is generated by at least reflection or backscattering on the measurement object (s = 2), or the measurement object Any x-coordinate and z-coordinate without depending on the x-coordinate and z-coordinate of the receiving aperture element that generates the received signal so that it is generated at least by transmission, forward scattering, or refraction (s = 1). One of the plurality of transmit aperture elements in the receive effective aperture element array, or one of a plurality of transmit aperture elements different from any of the receive aperture elements, Each of a plurality of transmit aperture elements in the transmit effective aperture element array having a non-zero constant y coordinate and positioned opposite the receive effective aperture element array.

When the y coordinate of the transmission aperture element is zero for each of the reception signal groups obtained by arranging the reception signals having the same distances Δx and Δz in the lateral x coordinate and the z coordinate between the transmission position and the reception position, , half the distance of a straight line distance connecting the transmission aperture element and interest points represented with the y coordinate of the point of interest comprising a transmit aperture position and distance and Δx and Δz and the received aperture element, or transmission aperture when the y coordinate of the element is non-zero, between the transmission aperture element and the point of interest and receive aperture element represented by using the y-coordinate and the distance Δx and Δz y-coordinate and the transmission aperture element Seki center point Using the distance, each of the image signals obtained by setting the deflection angle in the above-described monostatic type aperture plane synthesis is corrected with respect to the position in the horizontal direction in the frequency domain, and they are overlapped without performing interpolation approximation processing. Generate image signal Kill.

  Also, in order to generate an image signal representing the propagation of an unknown wave source or the wave it generates (so-called passive mode), the y coordinate of the estimated unknown wave source is set to the y coordinate of the transmission aperture element, It is good to perform beam forming. It is also effective to make observations while changing the y coordinate by trial and error. For example, effects such as image formation, increased spatial resolution, increased signal intensity, increased contrast, etc. should be obtained, and a series of processing is automatically performed using these as criteria. Is also possible.

As described below, as information on the wave source location or transmit aperture element, the position relative to the receiving aperture element, direction or distance of the position at which the direction of the opening, or, it is Ru Oh propagation direction of the wave to be generated is given. In addition, the time at which a wave is generated by an arbitrary wave source may be given. It may be observed by other devices, and the received signal itself or a wave propagating at a higher speed may be emitted and transmitted from the wave source.

  Obtain the center of gravity (center) frequency or instantaneous frequency of the multi-dimensional spectrum for the received signal, determine the direction in which the wave source exists or the propagation direction of the wave from this, adjust the deflection angle for transmission or reception, and adjust the beam Forming may be performed. In addition, the center-of-gravity (center) frequency or instantaneous frequency of the multi-dimensional spectrum is obtained from the beam-formed image signal, and the direction in which the wave source exists or the propagation direction of the wave is obtained from this, and the deflection angle of transmission or reception is obtained. The beam forming may be performed by adjusting. These processes can be performed in a plurality of reception apertures or reception effective apertures to geometrically determine the position or direction in which the wave source exists. These processes are useful and may be applied to other beam forming.

  As described in the method (2) for monostatic aperture synthesis, in the method (3) for multistatic aperture synthesis, an arbitrary beamforming can be generated using echo signals collected for aperture synthesis. (Actually, an image signal can be generated even if the processing described in the methods (1) and (4) to (7) is performed on these data). Although it may be effective that the amount of data is abundant compared to the monostatic type, the amount of calculation increases. In the plane wave processing of the method (1), the aperture plane synthesis processing can be performed by using a code. Further, in a convex transducer, sector scan, IVUS, or the like, when a wide wave is transmitted or received (cylindrical wave) in the angle θ direction in polar coordinates (r, θ) in the radius r direction (FIG. 7), When a wide wave is transmitted in the direction of the angle θ of the polar coordinate system (r, θ) in the same polar coordinate system (r, θ) as in FIG. (Fig. 8) and echo signals collected for aperture plane synthesis in the polar coordinate system, the Cartesian coordinates (x, y) are replaced with polar coordinates (r, θ) as in method (1). The image signal can be generated in a Cartesian coordinate system (x, y) or polar coordinates (r, θ). The same applies when other transmission beamforming is performed or when they are performed in a spherical coordinate system.

  Further, as described above, the deflection can be performed, but the same processing can be performed when the steering angles of the transmission beam forming and the reception beam forming are different. The conversion distance may be calculated using the distance between the transmission aperture element and the reception aperture element, the transmission steering angle and the reception steering angle, and in the case of the transmission type, the distance between the transmission aperture element and the reception element. In addition, apodization may or may not be performed at the time of transmission. In addition, since the reception apodization process is also a linear process, it can be performed at various timings (hardware or software). In consideration of the amount of calculation that depends on the effective aperture width and the like that determines the number of the above, it can be easily implemented at an appropriate timing. For example, each set for initiating generation of a low resolution echo signal can be weighted or apodized in the frequency domain or spatial domain to the generated low resolution signal.

Method (4): Fixed Focusing FIG. 12 is a schematic diagram of fixed focusing using a linear array. Fixed focusing is a method in which each element is delayed so that one point is a focus point and ultrasonic waves reach the focus point simultaneously. A part or all of the physical aperture of the array type transducer is received as an effective aperture, and the measurement target is scanned. Of course, steering may be performed. The transmission and reception steering angles may be different.

In the fixed focusing, the image signal is generated by the method (1): beam forming at the time of receiving a plane wave, or the method (3): multi-static aperture plane synthesis. In that case, there are the following three methods.
(I) Each received signal obtained in the effective aperture width is subjected to one image signal generation process on the superposition.
(Ii) A so-called normal low-resolution image signal is generated using the received signal for each transmission, and they are superimposed.
(Iii) Similar to the multi-static aperture plane synthesis, image signals are generated by setting the same transmission / reception positional relationship as a set, and then superimposed.

  When performing transmission and reception in the radius r direction of polar coordinates in convex transducers, sector scans, or IVUS, or when performing beamforming using a virtual source placed behind in an arbitrary aperture shape, Cartesian coordinates ( Processing may be performed by replacing x, y) with polar coordinates (r, θ), and an image signal can be generated at polar coordinates (r, θ). As described above, an interpolation approximation may be required after the image is generated. The same applies to transmission and reception using a spherical coordinate system. There is a report (Non-Patent Document 6) of processing performed with approximation processing when transmission focus is performed, and similarly, a result is obtained in polar coordinates (r, θ). The first inventor of the present application is a method for directly generating an image signal in a Cartesian coordinate system as a result of beam forming for transmission or reception in their polar coordinate system, spherical coordinate system, or arbitrary orthogonal curve coordinate system. (5-1), (5-1 ') and (5-2) were also invented. Apodization may be performed at the time of transmission, or reception apodization processing may be performed on the received signal (hardware at the time of reception or software after reception). When apodization is performed in software, it is performed according to method (1) or method (3).

Method (5): Image signal generation in a polar coordinate system Method (5) transmits or receives (part of) an ultrasonic cylindrical wave in a two-dimensional polar coordinate system (r, θ) such as convex array, sector scan, or IVUS. This is a method of generating an image signal in a Cartesian coordinate system in the case (see FIG. 7).

Hereinafter, polar coordinate display of Fourier transform will be described. The two-dimensional Fourier transform is expressed by equation (22).
Since the received echo signal in the polar coordinate system is expressed as f (r, θ), Equation (23) is established.
Therefore, the equation (24) is obtained through the Jacobi operation. In this way, the wave represented in the polar coordinate system can be decomposed into plane wave components (k _x , k _y ) in the Cartesian coordinate system. Similarly, a wave represented by arbitrary orthogonal curve coordinates can be decomposed into plane wave components (k _x , k _y ) in a Cartesian coordinate system.

Method (5-1): Cylindrical Wave Transmission or Reception Image Signal Generation FIG. 13 is a flowchart showing digital signal processing during cylindrical wave transmission. From Expression (24), the Fourier transform in the angle θ direction on the opening is expressed by Expression (25).
Here, r ₀ is the radius of curvature of the convex probe. In step S21, the received signal is Fourier-transformed with respect to time t, and in step S22, the received signal is Fourier-transformed (FFT) with respect to the angle θ, whereby the received signal in the polar coordinate system is converted into a plane wave component (k _x , k _y ).

Therefore, the image signal can be generated by performing wave number matching represented by the equation (26) (step S23) and performing inverse Fourier transform on the space (x, y).

  For example, in step S24, an angular spectrum for each depth y is calculated. Further, the frequency component k of the angular spectrum is added in step S25, and an inverse Fourier transform (IFFT) is performed on the horizontal wave number kx in step S26, whereby an image signal is obtained in step S27.

  This method does not require interpolation processing for wave number matching and coordinate system conversion to obtain image signal of Cartesian coordinate system (x, y) from polar coordinate system (r, θ) signal, and it is fast and highly accurate. Beam forming is performed. Similar to the plane wave transmission in a linear array transducer, a cylindrical wave can be deflected in a polar coordinate system. Apodization can be performed similarly. In the case of a cylindrical wave, at the different positions in the z-axis direction orthogonal to the two-dimensional polar coordinate system (that is, the z-axis in the cylindrical coordinate system (r, θ, z)) Although it is a time phase, the above processing may be performed by superimposing the received transmissions at different times. The z-axis direction may be focused by an analog device (lens), or arbitrary processing can be performed by the digital signal processing of the present invention. The same calculation can be performed when the wave propagation direction is in the center direction (for example, useful for various imaging or CT using a circular-based array transducer surrounding a HIFU treatment or an object). Of course, reception-only beamforming may be performed in them, and the same processing is performed. The received signal represented by polar coordinates (r, θ) can be processed by replacing the Cartesian coordinates (x, y) in method (1) with polar coordinates (r, θ). , θ), the image signal can be generated as described above, and interpolation approximation is performed in the subsequent processing. In these, similarly, steering can be performed.

Method (5-1 ′): Image signal generation using virtual source and other arbitrary shape aperture array When transmitting wave from arbitrary aperture shape such as linear array type transducer as well as circular aperture array A case where a part of a cylindrical wave is generated using the installed virtual source (FIG. 8) will be described.

  (I) When the received signal acquired for monostatic aperture plane synthesis is used, if necessary for the received signal transmitted and received in each element and stored in a memory or the like, a complex exponential function is applied to the Fourier transform. Multiplying the response of the wave emitted from the virtual source into a digital received signal represented by polar coordinates (r, θ), and then using method (5-1), directly (x, y) Image signals can be generated in the coordinate system. Similarly, the received signal can be represented as a digital signal of polar coordinates (r, θ), and the process of replacing the Cartesian coordinates (x, y) in method (1) with polar coordinates (r, θ) can be performed. An image signal can also be generated at (r, θ). Of course, monostatic processing of method (2) is also possible in the polar coordinate system (r, θ).

  (Ii) In addition, when using the received signal acquired for multi-static aperture plane synthesis, there is a need for the received signal transmitted in each element and received by the surrounding elements and stored in the memory etc. For example, multiply the Fourier transform by the complex exponential function, and use the response of the wave emitted from the virtual source as the digital received signal represented by polar coordinates (r, θ), and implement the multistatic aperture plane synthesis method (3) it can. As another process, the digital reception signal is superimposed on each reception element, and then the method (5-1) is used to directly generate the image signal in the (x, y) coordinate system. Similarly, it is possible to superimpose the digital reception signal at each receiving element, and then to perform the processing in which the Cartesian coordinates (x, y) in method (1) are read as polar coordinates (r, θ). An image signal can also be generated at (r, θ). Of course, the multi-static processing of the method (3) can be performed in the polar coordinate system (r, θ) without superposition.

  (Iii) In these processes, in order to omit the process of rewriting the signal received by the physical aperture array into the digital signal of the polar coordinate system (r, θ), the sampling is originally performed in the polar coordinate system (r, θ). A transmission or reception delay pattern may be used to transmit and receive samples from each aperture element. Based on the method (5-1), the method (2), and the method (3), an image signal can be directly generated in the (x, y) coordinate system. Similarly, the received signal is represented as a digital signal of polar coordinates (r, θ), and the processing in which the Cartesian coordinates (x, y) in methods (1) to (3) are replaced with polar coordinates (r, θ) is performed. It is also possible to generate an image signal in polar coordinates (r, θ).

(iv) Similarly, in the case of generating a part of a cylindrical wave using a virtual source installed at the rear in an arbitrary aperture shape (FIG. 8), it is received by each element in the above (i) to (iii). The received signal is represented as a digital signal in Cartesian coordinates (x, y) by multiplying the Fourier transform of the received signal stored in the memory or the like by a complex exponential function (however, time is required), and method (5-1) On the contrary, f (x, y) is Fourier-transformed with respect to the radius r and the angle θ and processed to generate an image signal in the polar coordinate system (r, θ). Alternatively, each method can be used to generate an image signal in a Cartesian coordinate system (x, y).
In (i) to (iv), various beam forming operations described in the method (5-1) can be performed.

Method (5-2): Image Signal Generation at Fixed Focus FIG. 14 is a schematic diagram of fixed focusing using a convex array. Also in the convex array, fixed focusing can be performed as shown in FIG. As in the case of the linear array type (method (4)), an image signal can be generated by the same calculation process as that for cylindrical wave transmission. That is, there are the following three methods based on the processing of method (1) or method (3).
(I) Each received signal obtained in the effective aperture width is subjected to one image signal generation process for superposition.
(Ii) A so-called normal low-resolution image signal is generated using the received signal for each transmission, and they are superimposed.
(Iii) Similar to the multi-static aperture plane synthesis, image signals are generated by setting the same transmission / reception positional relationship as a set, and then superimposed.
As described above, the image signal can be directly generated in the Cartesian coordinate system. However, the method (4) can be performed using the coordinate axes of the polar coordinate system to generate the image signal in the polar coordinate system. Similarly, deflection and apodization can be performed. The z-axis direction can be processed in the same manner as (5-1).
As described above, the beam forming of the methods (1) to (4) can be performed. However, the present invention is not limited thereto, and the same effect can be obtained by adapting to any beam forming.

Method (5-3): Image signal generation at the time of reception in a spherical coordinate system When a spherical core wave aperture element array is used, three-dimensional digital wave signal processing is performed. When the element array is used, the wave is received in the spherical coordinate system (r, θ, φ ), and thus the received signal of the received wave is expressed as f (r, θ, φ ). In this case as well, various beamforming can be performed through the Jacobi calculation, as in the case of the two-dimensional polar coordinate system (r, θ).

Specifically, a Cartesian coordinate system (by a three-dimensional Fourier transform performed on the received signal f (r, θ, φ ) to decompose the received wave into a plane wave in the Cartesian coordinate system (x, y, z). x, y, wavenumber or frequency domain of _{z) (k x, k y} , represented by formula k _z) to (27), x = rsinθcos φ , y = rcosθ, and, with z = rsinθsin φ The image signal can be directly generated in the Cartesian coordinate system without performing the interpolation approximation process by calculating as shown in Expression (28) by Jacobi calculation. Of course, the beam forming of the methods (1) to (4) can be performed, but the present invention is not limited to these methods, and the same effect can be obtained by adapting to any beam forming.

Method (5 "): Image signal generation in an arbitrary orthogonal curve coordinate system when transmitted or received in a Cartesian coordinate system In contrast to the above-described series of methods, reception obtained by transmitting or receiving in a Cartesian coordinate system An image signal represented by a two-dimensional polar coordinate system or a spherical coordinate system can be directly obtained from the signal without performing interpolation approximation, and can be realized by a similar calculation, for example, if the received signal is f (x, y, z), a Fourier transform in the r, θ, and φ directions and a calculation to decompose the received signal into a circular wave or a spherical wave corresponding to a plane wave in a Cartesian coordinate system may be performed through a Jacobian operation. These methods may also be used when changing the FOV (eg, can be broad).

Method (6): Migration Method Also in the migration process, the apparatus of the present invention can perform the processing without performing the interpolation approximation process in the wave number matching. The migration equation (the following equation (M6 ′)) itself is well known, and the derivation of the equation is also well known, so the derivation of the equation is omitted here.

  Non-Patent Document 7 is based on normal migration processing based on 1-element reception based on 1-element transmission (that is, processing that does not deflect using transmission / reception data for monostatic aperture surface synthesis in method (2)). In the case of plane wave transmission and / or reception with and without steering (processing corresponding to method (1)), a wave is generated from an arbitrary transmission aperture element for any identical position. Since the propagation time, which is the time until the wave is received by the reception aperture element that also serves as the transmission aperture element, is different from that in the case of the normal migration, the propagation speed and the coordinates of the target position are reread (the following formula (M1)) , A method of calculating a value represented by the same form (formula (M6)) is disclosed.

  However, the processing of the other methods (2) to (5) is not disclosed in Non-Patent Document 7 (when steering is performed in method (2), it is not disclosed). Furthermore, in calculating the equation (M6 ′), conventionally, interpolation approximation has been performed when performing wave number matching (equation (M4) and equation (M4 ′)). In the apparatus of the present invention, Wave number matching is performed with high accuracy without performing interpolation approximation (formula (M7) and formula (M7 ′)).

Take a two-dimensional coordinate with the horizontal direction as the x-axis and the depth direction as the y-axis, and the time coordinate as t. Specifically, in the normal migration, the propagation time required for the wave to reciprocate between the arbitrary aperture element position (x, 0) and the arbitrary position (x _s , y _s ) is expressed by the equation (M0). Is done.

On the other hand, in the plane wave transmission with the steering angle θ (including 0 °), the propagation time is expressed by the equation (M0 ′).

Therefore, in the calculation performed based on the migration method at the time of deflection plane wave transmission in method (1), each of the transport speed c and the coordinate system (x _s , y _s ) representing the target position is replaced with equation (M1). A normal migration formula is calculated (formula (M4) and formula (M5)).

  In summary, among the methods (1) to (5), migration is performed in the same manner except for normal migration that performs non-deflecting processing using transmission / reception data for monostatic aperture surface synthesis in method (2). It can be processed. For example, the calculation procedure of migration during deflection plane wave transmission (including 0 °) in method (1) will be mainly described.

  FIG. 15 is a flowchart showing migration processing when a deflected plane wave is transmitted. When the received signal is represented as r (x, y, t), the received signal at the aperture element array position is represented as r (x, y = 0, t).

First, as shown in the equation (M2), the received signal is subjected to two-dimensional Fourier transform with respect to time t and the horizontal direction x (two-dimensional fast Fourier transform is good).
Here, k = ω / c, and the wave number k and the angular frequency (angular frequency) ω are related by a proportional constant 1 / c and correspond one-to-one, and can be expressed using ω instead of k Can be calculated.

  As described above, a special two-dimensional fast Fourier transform method can also be used. As a general method, first, in step S31, a time t The spectrum of the analytic signal is obtained by performing a fast Fourier transform (FFT) on. In addition, fast Fourier transform in the horizontal direction x may be performed at each frequency coordinate in the band k (faster than calculating each two-dimensional spectrum according to the equation (M2)).

When the plane wave is not deflected and transmitted, the above calculation may be performed, but in order to cope with the deflection, the trimming must be performed. For this purpose, in step S32, the above-described time t is used for trimming. Multiplying R ′ (x, 0, k) after fast Fourier transform with respect to complex exponential function (M3) (similar to complex exponential function (11) in method (1), fast Fourier transform and complex exponential function with respect to time t) The multiplication operation can be calculated directly at once, or a dedicated fast Fourier transform capable of such calculation is also useful).

In step S33, the received signal is subjected to fast Fourier transform (FFT) in the horizontal direction x. Here, the result is expressed as R ″ (k _x , 0, k). By the way, even if it is programmed so that trimming can be performed, a case where a plane wave is transmitted without deflection (steering angle 0 °) can be processed.

Normally, wave number matching (or mapping) is then performed. In the case of the methods (1) to (5) other than the normal migration (when the steering is not performed in the method (2)), the propagation velocity c and the coordinate system (x _s , y _s ) are expressed by the above formula. As shown in (M1), the propagation speed (E1) and the coordinate system (E2) for each beamforming are read and processed.

For the two-dimensional Fourier transform R ″ (k _x , 0, k) calculated in the case of a method (including method (1)) other than normal migration (when method (2) is not steering), Or, for the above R (k _x , 0, k) calculated in normal migration, through interpolation approximation (such as bi-linear interpolation using the angular spectrum closest to the frequency coordinate) , Wave number matching represented by Expression (M4) or Expression (M4 ′) is performed.

In this way, wave number matching is performed to obtain the following function (M4 ″).
Further, using the function (M4 ″), the following equation (M5) or equation (M5 ′) is obtained.

'To the formula (M6) or formula (M6 formula (M5) or (M5)' as represented by) by performing two-dimensional inverse Fourier transform about the wave number _{k x} and wavenumber (E3), image A signal f (x, y) is generated.
The two-dimensional inverse Fourier transform in the calculation of the equations (M6) and (M6 ′) may be performed by performing a fast two-dimensional inverse Fourier transform (IFFT), and a special fast two-dimensional inverse Fourier transform can be used. As a general method, in each of the equations (M6) and (M6 ′), first, a fast inverse Fourier transform for one wave number k _x in the signal band is performed on the other wave number (E3). Then, a fast inverse Fourier transform with respect to the wave number k _x (within the signal band) may be performed on each coordinate of the generated spatial coordinate y (each of the two-dimensional image signal is expressed by Equation (M6) or Faster than calculating according to equation (M6 ′)).

Non-Patent Document 7 does not disclose a formula (M6) that uses y _S in the formula, but discloses that calculation is performed using y instead of y _S , and correction of coordinates is performed after the calculation. . The correction of the coordinates is performed without approximation processing by performing approximation processing or by multiplying the time based on the multiplication of the complex exponential function which is the past invention of the first inventor of the present application. Equation (M6) can also be used when the deflection angle is 0 °.

In the apparatus of the present invention, wave number matching is performed together with a two-dimensional inverse Fourier transform or with an inverse Fourier transform in the depth direction without interpolation approximation. That is, the two-dimensional Fourier transform R ″ (k _x , 0, k) calculated in the case of a method (including method (1)) other than the normal migration method (when method (2) is not steering) is used. On the other hand, for the above R (k _x , 0, k) calculated in the normal migration method, first, as represented by the equation (M7) or (M7 ′), Integration for k is performed for each k _x , wave number matching of the wave number E (3) in the depth direction and inverse Fourier transform (IFFT) are performed simultaneously (step S34), and then the lateral (x) direction Performs fast inverse Fourier transform.
Non-Patent Document 7 does not disclose the formula (M7) using y _S in the formula. Equation (M7) can also be used when the deflection angle is 0 °. Similar to the methods (1) to (6), after adding the frequency k components of the spectrum, the inverse Fourier transform (IFFT) with respect to the wave number k _x in the lateral direction is performed, and the calculation can be performed by one inverse Fourier transform. Calculation is fast.

Further, in the process of calculating the formula (M6) and the formula (M7), in the process of calculating the formula (M6) and the formula (M7), when the migration is different from the normal migration (the processing corresponding to the case of no steering in the method (2)). It can be performed. For example, when the deflection plane wave of the method (1) is transmitted, first, in step S34, as described above, the calculation relating to the wave number E (3) is performed, and in step S35, each result is obtained for position correction. against determined function (M8), multiplied by a complex exponential function (M9), carried out thereafter, in step S36, inverse fast Fourier transform relates to lateral wavenumber _{k x} a (IFFT). Alternatively, it may be calculated by multiplying the complex exponential function of the inverse Fourier transform with respect to the wave number k _{x in the} horizontal direction by multiplying the equation (M9), or a dedicated fast inverse Fourier transform may be performed. Equation (M9) can also be used when the deflection angle is 0 °. As described above, the image signal f (x, y) is generated in step S37.
In summary, new processing can be performed using the equation (M6), the equation (M7), or the equation (M7 ′), and the image signal f (x, y) is removed at high speed except for errors due to interpolation approximation. ) Can be generated.

  Here, the description has mainly been given of performing the beam forming at the time of plane wave transmission with and without steering in the method (1) at high speed without interpolation approximation in wave number matching using the migration method. Method (2) (monostatic aperture synthesis method including the case of steering), method (3) (multistatic method with or without steering), method (4) (transmission fixed focus with or without steering), and All the beam forming described in each of the methods (5) (Beam forming in a polar coordinate system or an arbitrary orthogonal coordinate system) can be similarly performed. The same processing can be performed when the deflection angle differs between transmission and reception.

Method (7): Others Although the above methods (1) to (6) have been described with respect to the case of using a one-dimensional array, in the case of a two-dimensional array or a three-dimensional array, One or the other two axial directions may be similarly processed in the horizontal direction. That is, the above methods (1) to (6) may be simply extended to higher order dimensions.

  Further, in the above description, calculation of a product with a weight value that has a small amount of calculation and is easy for apodization processing has been described. However, the present invention is not limited to this, and in a linear system, a spatial domain and a frequency domain are calculated. Convolution integration may be performed based on the dual relationship between the product and the convolution integration in. It is possible to appropriately apodize at each depth position or at equal distances from each aperture element.

  By using the methods (1) to (6) to superimpose multidirectional deflected beams and plane waves generated by the apparatus according to the present embodiment, the above-described lateral modulation signal (image signal) and a wide band in the lateral direction are used. In some cases, a signal (image signal) having a high resolution in the horizontal direction is generated. In addition, a plurality of waves having different carrier frequencies may be used to generate a signal (image signal) having a wide bandwidth in the axial direction and a high resolution in the axial direction. In these cases, the spectrum may be widened to increase the resolution so that the spectra overlap. The plurality of beams may be generated in parallel at the same time, and the measurement target has the same time phase, but may be generated at different times. Multidirectional waves may be generated by the multidirectional aperture plane synthesis described above.

  Further, it is different to form a multi-focus (including not only a normal multi-focus that forms a transmission focus at a plurality of positions in the beam propagation direction but also a transmission focus at a plurality of arbitrary positions including the horizontal direction). There may be a case where a plurality of waves focused on the position are transmitted to perform reception beam forming. In addition, processing for generating reception beams at a plurality of positions and reception beams in a plurality of directions may be performed on one transmission beam. In addition, beam forming based on transmission in a plurality of directions with different steering angles may be performed. In addition, there is a case where beam forming is performed at a position where there is little interference, and beam forming is performed at each part divided within one frame on the basis of performing transmission and reception. In some cases, parallel beamforming is performed, such as processing in parallel, and in each case, processing is performed to superimpose the results at each position in the region of interest from which a plurality of beamforming results are obtained.

  In addition, the wave transmission / reception apertures may be dedicated apertures, but they may also serve as both, and not only receive the response of the wave transmitted by themselves, but are transmitted from other apertures. Waves may be received and again the generated beamforming results may be superimposed, including when processed in parallel. In summary, the above superposition is performed at the same time, at the same time, or at the same time or at the same time when the state of the object to be propagated (communication object) or the observation object is the same or substantially the same. In phase, one or more beamforming or transmission or reception may occur at each aperture, and similarly one or more beamforming or transmission or reception may be performed with one combination of apertures. Sometimes done. Similarly, each of a plurality of combinations of apertures may perform one or more beamforming, transmission, or reception. Also, in these cases, when a plurality of beamforming or transmission or reception results are obtained, new data may be generated through the calculation of the superposition thereof.

  Since these superposition processes are linear processes, a plurality of complex spectrum signals having the same frequency in the frequency domain can be superposed in the calculation process of the above methods (1) to (6). In this case, it is only necessary to perform inverse Fourier transform on the superimposed complex spectrum at one time. Processing can be completed faster than necessary. Although not limited to this, such as an incoming wave, what is superimposed in the state of an angular spectrum may be processed in a single direction or a plurality of directions, for example. As the processing itself, it is preferable to perform a Fourier transform by superimposing a plurality of waves in a spatial domain, and obtain a superposed angular spectrum (the effect of performing the Fourier transform only once). In some cases, the position of the object can be confirmed.

  In the above, when transmitting a plurality of beam-formed waves (at least, a predetermined transmission delay is applied and a transmission apodization may be applied) (among methods (1) to (6)) In methods (2) and (3) other than the aperture plane synthesis), the first excited aperture element in the effective aperture array for each wave transmitted when physically transmitted simultaneously Since each received signal is stored in a memory or a storage device (storage medium) in an overlapped state, the image signal generation process for one frame may be performed according to each method. (Parallel processing may be performed in which one frame is divided and processed in each part).

  On the other hand, in the above-mentioned another case where beam forming is performed a plurality of times at different times, in the channel of each receiving aperture element, the timing transmitted from the aperture element that is excited first in the effective aperture array can be grasped. In the apparatus according to the embodiment, in the digital signal processing unit, a plurality of received signals can be appropriately overlapped and processed in the same manner to obtain the same signal as the received signal when a plurality of waves are transmitted simultaneously ( In this case as well, parallel processing may be performed in which one frame is divided and processed in each part). In these cases, the first Fourier transform is substantially one time (there may be divided and processed in each part).

  In such an active state, beam forming can be completed at a higher speed in beam forming excluding aperture plane synthesis (methods (2) and (3)). However, the aperture-synthesized received signals collected for the methods (2) and (3) are subjected to transmission beamforming (transmission delay or transmission apodization is applied as necessary) and superimposed as necessary. May be processed in the same way. By the way, if the received signals are superimposed without applying a transmission delay, in this case, a received signal when a plane wave is transmitted without steering can be generated. Even in the aperture plane synthesis process, division parallel processing may be performed to increase the speed. A multi-directional beam can be generated from signals collected in one time phase, and when processed in the apparatus or method of the present invention, obtained by a single Fourier transform under the deflection angle in each direction. Calculations using the same angular spectrum data are performed, and finally, the multidimensional spectra obtained for each deflection angle are overlapped without performing multiple inverse Fourier transforms, and the multidimensional spectra are superimposed. A final image signal can be generated at a high speed by performing inverse Fourier transform times (division processing may be performed). However, in the case of performing passive processing even in fixed focusing of reception or other beam forming, whether for aperture synthesis, as described above, with respect to the superimposed received signal (that is, one angular spectrum), for example, It is effective to perform processing in a single direction or in different directions.

  In addition, in the case where a superposition of a plurality of waves obtained in these processes is obtained, it is also effective to separate the spectrum if the propagation direction, frequency, or band is different, for example. In addition, encoding, MIMO (Multiple-input and Multiple-output: a wireless communication technology for expanding the band of transmission and reception signals by combining a plurality of antennas on the transmission side and reception side), and SIMO (Single-input and Multiple-output: (Wireless communication technology that uses one antenna on the transmitting side and uses multiple antennas on the receiving side to widen the band of received signals), MUSIC (Multiple Signal Classification: Wireless communication technology that uses eigenvalues or eigenvectors of the correlation matrix of received signals) Separation in the digital signal unit using independent signal separation, sign, or parametric methods, etc. Can. Note that the overlay process may be effective in other cases (for example, the SN ratio is improved by using a plurality of signals obtained in the same phase).

  On the other hand, in the methods (1) to (6), after the wave number matching is performed on the received signal stored in the memory or the storage device (storage medium) to frequency-divide the spectrum and generate the image signal of one frame. In some cases, a plurality of waves processed in a situation where the spectrum is divided in the frequency domain to be processed is obtained. Even when a plurality of waves overlap, the spectrum may be frequency-divided. This corresponds to the generation of a physically pseudo wave having new wave parameters (frequency, band, propagation direction, etc.) by frequency division of these spectra.

  Using a plurality of waves generated in these processes, the digital signal unit uses a displacement vector that moves in an arbitrary direction (such as a multidimensional autocorrelation method or a multidimensional self-Doppler method to solve simultaneous equations related to the displacement vector component). In this way, the first inventor's past invention of the present application or a normal one-direction displacement is measured with high accuracy (more equations than the number of displacement components to be obtained are derived and overdetermined (over- In a determined system, the least squares method, the average value of the calculation results, and high-precision and high-precision results are obtained in a state where the waves overlap and have a high frequency and a wide band). Displacement may be measured by applying the Doppler method to a single wave itself. From the displacement (vector), strain (tensor), strain velocity (tensor), velocity (vector), and acceleration (vector) are obtained by partial differentiation using a differential filter related to space or time.

  There are various techniques to detect and image the movement of the target based on the observed waves. For example, in the field of medical ultrasound, based on the average velocity and dispersion of blood flow and tissue displacement and deformation. Some of them can display speed information, presence / absence of movement, complexity, and the like. A contrast agent (microbubble) is actively used, and measurement imaging may be performed in a state where the intensity of the wave from blood in the blood vessel or the heart chamber is increased. It may be useful not only for morphological observation but also for functional measurement. As a self-emanating contrast agent, a radioisotope used in PET (Positron Emission Tomography) is a typical example, and observation based on a count of the number of occurrences is performed. This is the target type of the passive device of the second embodiment. For example, a magnetic substance (which may have an affinity for a target such as a cancer lesion) is intravenously injected, and then mechanically there. There is also a case where a magnetic field is generated by applying vibration (the past invention of the first inventor of the present application). Accordingly, the transmission transducer is dynamically stimulated, and as a response, the electromagnetic wave is observed by the reception transducer. There are also examples such as the above-mentioned photoacoustic.

  In addition, the wave is separated before the last inverse Fourier transform and detected (square detection, envelope detection, etc.), separated after the last inverse Fourier transform and then detected, or separated from the original Can be detected before and after Fourier transform (Non-Patent Document 1), and imaging representing the intensity distribution of each wave is performed, or incoherent signals resulting from the detection are superimposed. Emphasize deterministic signals (eg reflected or specular signals), reduce stochastic signals (eg scattered or speckle signals), and space in the structure of objects and media The change is effectively depicted (the past invention of the first inventor of the present application).

  In some cases, a coherent signal with overlapping waves is detected and its intensity distribution is imaged. In addition, a non-detected coherent signal may be imaged to image the wave itself, or an image of a phase distribution obtained together with an image of signal strength (amplitude) may be presented. A single wave may be similarly imaged.

  Gray images and color images are popular (popular). If quantitativeness is required, numerical values corresponding to the displayed brightness and color may be displayed as bars. is there. In addition, it may be displayed as a bird's eye view or the like, or may be displayed together with CG. They may be displayed as still images or videos, videos may be displayed frozen, they may be displayed in real time, or processed and displayed offline. There is also. Wave data or image data stored in a storage device (or storage medium) may be read out and displayed. An arbitrary numerical change with time may be displayed as a graph.

  In addition, for example, it is also possible to observe the temperature distribution of the measurement object using a microwave, an infrared ray, or a terahertz band signal. The wave transmitted to the radiating object is modulated and detected (the passive device according to the second embodiment also measures the temperature distribution of the target from the radiated wave itself. Sometimes). Based on these observed physical and chemical quantities, high-order processing such as an inverse problem approach is performed, and viscoelastic modulus, elastic modulus, viscosity, thermal properties, and electrical properties (conductivity and dielectric constant). , Permeability, wave propagation speed (light speed, sound speed, etc.), attenuation, scattering (forward scattering, backscattering, etc.), transmission, reflection, refraction, or wave source may be required including frequency dispersion. .

  Physical quantities such as measured displacement and temperature may be displayed in the same manner, but may be displayed superimposed on the morphological image obtained at the same time. An image representing these distributions is often required to be quantitative, and numerical values corresponding to the displayed luminance and color may be displayed as bars. In addition, it may be displayed in a bird's eye view or the like, or may be displayed in combination with CG. They may be displayed as still images or videos, videos may be displayed frozen, they may be displayed in real time, or processed and displayed offline. There is also. Wave data or image data stored in a storage device (or storage medium) may be read out and displayed. An arbitrary numerical change with time may be displayed as a graph.

  Further, additional information on the wave to be observed may be provided from another device through the input device, and observation data of other physical quantities or chemical amounts may be provided. In the digital signal processing unit, In addition to the above processing, data mining, independent signal separation, code, multidimensional spectral analysis, signal separation by MIMO, SIMO, MUSIC, signal separation based on object identification by parametric methods, these methods may be used in combination Super-resolution or higher-order processing such as ISAR (Inverse synthetic aperture) may be performed.

  These processes are also performed in the passive device according to the second embodiment, and will be described in detail there. However, unlike the passive device, the active device according to the present embodiment has a wave motion. The position of interest can be specified in the received signal that is received is greatly different, and if transmission focus or multifocus is performed, the state and function of those focus positions, and the wave source there If there is any information about the wave source, it modulates and demodulates the waves with high resolution and understands them. Also, plane waves (flat arrays), cylindrical waves (ring-shaped arrays), spherical waves (spherical shell-shaped arrays) It is possible to capture them at a high frame rate and at high speed by using similar waves.

  In communication, the position of the communication destination can be narrowed down from the transmission transducer, and energy saving and communication security can be improved. In performing the observation, the degree of freedom is high in configuring the measurement system. Further, in the processing based on these system theories, it is easy to identify the point spread function to be generated and adjust it according to the purpose. It is possible to use multiple transmitting and receiving transducers (sometimes serving as transmitting transducers), and the waves to be transmitted and received may be the same or different. As mentioned above, a plurality of device bodies dedicated to a plurality of transducers operating in synchronization may be used, or a passive device according to the second embodiment may be used together. It may be connected to other devices including a device for controlling the network through a dedicated or normal network, or the device main body may have a network control function.

  Based on various observation data, devices such as materials and structures manufacturing devices, treatment and repair devices, and applied devices (robots, etc.) may operate in conjunction with each other, but are not limited thereto. . In addition, measurement and high-order calculation processing using these waves may be performed by another device using wave data stored in a removable storage device (storage medium). Data may be stored in the same type of storage device (storage medium) and used in another device.

  Note that if the received signal received and stored in the memory or storage device (storage medium) contains harmonic components generated in the target or medium, the fundamental wave or harmonics before the beamforming process is performed. A beam forming process (normal phasing addition) may be performed by separating a wave (sometimes only the second harmonic and sometimes dealing with multiple harmonics without ignoring higher-order components) However, it may be separated after beamforming is performed. In the separation method, there is one that separates the spectrum in the frequency domain, but there are cases where bands overlap, and so-called medical ultrasonic waves generate waves with opposite polarities in the simultaneous phase called the pulse inversion method In the apparatus according to the present embodiment, when the received signals for each transmission are superimposed before or after beamforming, the second harmonic component can be extracted and the fundamental wave can also be obtained.

  In addition, a method of separating using a polynomial is also known. In the apparatus according to the present embodiment, one-dimensional processing of the wave propagation direction, or when the wave is modulated in the lateral direction, It is possible to perform multidimensional processing taking into account changes in position and can be performed before or after beamforming. However, in the case of performing beam forming after separation, when performing beam forming of each of the fundamental wave and the harmonic wave, each beam forming process is performed. Although processing may be performed, separation after beam forming is faster.

  On the other hand, when the wave transmitted from each transmission aperture is encoded, the wave generated from which transmission aperture element is generated with respect to the reception signal received by each reception aperture element when performing beamforming. The components are separated by signal detection based on a matched filter, and not only dynamic focusing for reception but also dynamic focusing for transmission may be performed, which is widely known. This is effective for high-speed transmission by plane wave transmission, and is also effective when a focus beam or steering is performed.

  When transmitting a plurality of waves or beams at the same time, for example, the above-mentioned plurality of waves having different frequencies and a plurality of different propagation directions are transmitted as encoded signals, and received signals May be decoded in the same manner and separated into received signals generated by their respective waves and transmission beams. This is effective, for example, in the case where the propagation directions are the same due to waves with overlapping bands, refraction, reflection, transmission, scattering, or the like. This is based on the basic idea of encoding the separated waves with another code. It may be simply encoded under the same physical parameters.

  In these, simultaneous equations can be solved, but the processing is fast and the effect of a matched filter can be obtained. Codes suitable for the target and medium have also been developed. However, as the number of elements used increases, the code length increases and the signal energy increases. It is important to make effective use of this, but on the other hand, for example, if the target or medium is deformed, the accuracy is increased. Is known to be unsuitable due to a decrease in the frequency, and the same problem occurs in chirp signal compression.

  In communication, information is encoded on the wave transmitted from each transmission aperture element, and then coded and transmitted (for example, a plane wave, a cylindrical wave, or a spherical wave is used as beam forming) If the information is widely communicated, focusing may be performed at multiple positions, the accuracy at those positions is guaranteed, and security may be ensured to communicate with local or specific objects, or energy may be saved. ) The received signal is subjected to beam forming and then decoded. The application of encoding in the apparatus according to the present embodiment is not limited thereto, but these processes are performed in a digital signal processing unit (also including a memory built-in type), a memory, or a storage device (storage medium). .

  In addition, physical quantities (size, direction, temperature, etc. of displacement, velocity, acceleration, strain, strain rate, etc.), chemical amounts, or additional information that are observed by the apparatus according to this embodiment or provided by others. In addition, viscoelasticity and elastic modulus, viscosity, thermophysical properties, electrical properties (conductivity and dielectric constant) related to wave, obtained through the above high-order processing such as inverse problem approach, transparency Based on magnetic susceptibility, wave propagation speed (speed of light, sound speed, etc.), attenuation, scattering, transmission, reflection, refraction, wave source, material, structure, or their frequency dispersion, etc. Beamforming parameters (transmission intensity, transmission and reception apodization, transmission and reception delay, steering angle, transmission and reception time intervals (scan rate), frame rate, number of scanning lines, number of effective apertures, etc. shape Magnitude and direction and position, shape and size and direction of the aperture element, the physical opening orientation, or polarization mode, etc.) may be optimized. Thus, for example, spatially uniform quality (spatial resolution, contrast, scan rate, etc.), and certain targets (based on shape, material, structure, motion characteristics, temperature, humidity, etc.) can be detected High-quality (spatial resolution, contrast, scan rate, etc.) at the target position and related positions. Scattered waves (forward scattered waves or backscattered waves), transmitted waves, and reflections according to the movement, composition, and structure of the target. Optimized beamforming is performed, such as appropriately capturing a wave or a refracted wave, or observing from a wide direction.

  The wave propagation speed is determined by the physical properties of the medium, but the physical properties vary depending on the environmental conditions such as pressure, temperature, and humidity, and the physical properties are often inhomogeneous in the medium. It is. The propagation velocity may be measured in real time, and the propagation velocity can be obtained from the observed environmental conditions based on calibration data for the environmental conditions. The apparatus according to the present embodiment further includes a phase aberration correction unit that corrects the inhomogeneity of the propagation velocity, and substantially adjusts the transmission delay of each channel described above or the delay dedicated to correction during transmission. Phase aberration correction can be performed. Further, after reception, the digital signal unit can be corrected by multiplication with a complex exponential function in the digital signal unit in order to correct non-uniformity in propagation speed in the transmission and / or reception propagation path. Alternatively, it is also possible to perform correction directly in the calculation of the Fourier transform and the inverse Fourier transform. The reliability of the measured propagation velocity is determined by generating an imaging signal for the measurement object itself or a reference object that exists in the vicinity of the measurement object, and the imaging state, spatial resolution, signal intensity, contrast, etc. It can be confirmed as an index, and it may be further adjusted based on this. Also in the second embodiment, which will be described later, transmission and / or reception phase aberration correction may be performed after reception.

  A wave propagates and spreads under the influence of attenuation, scattering, transmission, reflection, refraction, and the like. Basically, the intensity of the wave decreases with the propagation distance. Therefore, in the apparatus according to the present embodiment, for example, based on Lambert's law, a function for correcting the attenuation of the signal before or after beamforming is installed, or the operator reduces the attenuation from the input apparatus. There is a case where a function capable of adjusting the correction at each position and each distance is provided. However, as described above, there is a case where a function of performing an optimal correction before or after the beam forming process in conformity with an object may be provided. In these processes, although the degree of freedom is low, analog processing by an analog device or a circuit may be performed instead of digital processing with an emphasis on high-speed processing.

  In the above processing, superposition and spectral frequency division were linear processing. However, after the generation or generation of the wave by the beam forming in the above methods (1) to (6), nonlinear processing is performed, A signal having a wave parameter is generated (past invention of the first inventor of the present application). In the beam forming process, when the received signal is an analog signal, it is based on analog signal processing using an analog circuit (diode, transistor, amplifier, dedicated non-linear circuit, etc.), and when it is a digital signal, digital using a digital signal processing unit Based on the signal processing, the received signal may be subjected to a power operation, multiplication operation, or other non-linear processing.

  In addition, as a modification of DAS, DAM (Delay and Multiplication) processing, which is the past invention of the first inventor of the present application, may be performed in the frequency domain in the apparatus of the present invention. Calculation of products such as power and multiplication in the space-time domain can be performed by convolution integration in the frequency domain. For signals that have a higher frequency, a wider band, simulated harmonics, or a steered wave, it is possible to obtain a signal that has been detected from at least one arbitrary direction in all directions. For example, the resulting wave In some cases, a displacement vector can be measured using a normal one-direction displacement measurement method.

It is also possible to generate an imaging signal using a virtual source. As for the virtual source, there have been reported in the past that the virtual source is installed before the physical aperture and the virtual source is installed at the transmission focal point position. It is reported that detectors can be installed at arbitrary positions, and physical sources of waves and detectors can be installed with appropriate scatterers and diffraction gratings at arbitrary positions. It can also be implemented in virtual detectors. It is possible to increase the spatial resolution and widen the field of view (FOV).

A coordinate system in which the wave is rotated by a coordinate system determined by the receiving aperture element array around an arbitrary position or spatially shifted by an arbitrary wave source (for example, the coordinate of the axis and the horizontal axis of the transmission aperture) In some cases, the beam forming is performed after correcting the coordinates of the received signal. For example, the two-dimensional Cartesian coordinate system (x, y) if it is desired imaging signals directly to the product in the state of being rotated only θ around the origin is obtained more Fourier transform for the first time direction analysis It is sufficient to proceed with the calculation by multiplying the signal by the equation (29), rather than performing the rotation of the wave vector (kx, √ (k ² -kx ² )) and coordinates (x, y) and the Jacobian. The image signal can be generated at high speed without losing the high speed achieved by the present invention.

However, in the case of a reflected wave, s = 2, and in the case of a transmitted wave, s = 1. If the transmission is substantially corrected, it may be carried out with s = 1. Spatial shifting (translation) can also be performed by multiplying a complex exponential function in the frequency domain. The above-described method for calculating the wave vector (kx, √ (k ² -kx ² )) and coordinates (x, y) and calculating the Jacobian is a transmission beamforming involving conversion to a coordinate system determined by the receiving aperture element array. (S = 1) is performed, and under the circumstances, reception beamforming (s = 1) is performed and the speed is low.

In the active type device according to the present embodiment, the same applies to the passive type device according to the second embodiment to be described later, but as an analog device, it may be incorporated in the transducer or the device body. Lenses and reflectors (mirrors), scatterers, deflectors, polarizers, polarizers, absorbers (attenuators), multipliers, conjugates, phase delay devices, adders, differentiators, integrators, matching devices, Special devices such as filters (space or time, frequency), diffraction gratings, spectrometers, collimators, splitters, directional couplers, or nonlinear media, wave amplifiers may be used in combination. In addition, for light, polarization filter, ND filter, shield, optical waveguide, optical fiber, optical Kerr effect device, nonlinear optical fiber, optical mixing optical fiber, optical fiber for modulation, optical confinement device, optical memory, dispersion shifted optical fiber , Bandpass filters, time inverters, encoding using optical masks, etc., and optical node technology, optical cross-connect (OXC), optical, etc. to control them (wavelength conversion, switching, routing) An add / drop multiplexer (OADM), an optical multiplexer / demultiplexer, or an optical switch element is used, and the device itself may be an optical transmission network or an optical network. This is not the case. In beamforming, they are to be controlled with the device either personally, naturally, or equally optimally under the mechanism described above.

Also, under such a combination, the device according to the present invention is also used in a normal device using waves. Examples of medical devices include ultrasonic diagnostic devices (echo method and transmission type), X-ray CT (contrast agents that enhance attenuation effects may be used), X-ray X-rays, and angiography. , Mammography, magnetic resonance imaging (MRI), OCT (Optical Coherent Tomography), PET (Positron Emission Tomography, applicable to the second embodiment), SPECT (Single Photon Emission Computed Tomography) , Endoscopes (also capsule type), laparoscopes, catheters equipped with various sensing functions, various microscopes, various radiotherapy devices (sometimes used in combination with chemotherapy to enhance therapeutic effects), and HIFU ( High Intensity Focus Ultrasound). A chemical sensor or the like may be used. The apparatus according to the present invention is also used in various radars, sonars, optical system apparatuses, and the like. The wave is not limited to a pulse wave or a burst wave, and a continuous wave may be used. Also, digital processing with a high degree of freedom may be realized and used by a dedicated analog circuit with a fast operating time, and vice versa. There are various devices in each field such as resource exploration, non-destructive inspection, and communication, and the device according to the present invention is also used in these devices. The apparatus of the present invention, as a device, also, the operation mode (for example, Imaging mode, Doppler mode, measurement mode, communication mode, etc.) with respect are those can be used in conventional equipment, also those things or the It is not limited to.

<Simulation results>
The following mainly shows the results of confirming the feasibility of the beam forming methods (1) to (7) by simulation when the wave is ultrasonic waves (plane wave transmission and monostatic opening during steering). In addition to surface synthesis, multi-static aperture surface synthesis, image signal generation by fixed focusing, image signal generation in Cartesian coordinate system during transmission and reception in polar coordinate system, result of migration method).

  FIG. 16 is a diagram showing a numerical phantom used in the simulation. Here, a numerical phantom including five point scatterers existing at an interval of 2.5 mm at a depth of 30 mm in an echo-free and non-attenuating medium was handled. Field II (see Non-Patent Document 8) was used to generate the echo signal. Here, the depth direction is the z-axis and the horizontal direction is the x-axis.

  In the plane wave transmission, the migration method, and the monostatic aperture surface synthesis, a one-dimensional linear array transducer (128 elements, element width 0.1 mm, gap 0.025 mm, slice direction thickness 5 mm) was used. In fixed focusing and multi-static aperture synthesis, a one-dimensional linear array transducer (256 elements, element width 0.1 mm, gap 0.025 mm, slice direction thickness 5 mm, effective aperture width 33 to 129 elements) was used. A convex transducer (128 elements, element width 0.1 mm, gap 0.025 mm, slice direction thickness 5 mm, curvature radius 30 mm) was used for transmission and reception in the polar coordinate system. The center frequency of the emitted ultrasonic pulse is 3 MHz, and its sound pressure waveform is shown in FIG. The deflection angle is defined with respect to the depth direction of the front, and will be represented as “θ” in the following.

(1) Transmission of deflection plane wave FIG. 18 shows a simulation result when a deflection plane wave having a deflection angle θ = 0 °, 5 °, 10 °, and 15 ° is transmitted. This is a result of reception at the same angle. In FIG. 18, the horizontal axis represents the position [mm] in the horizontal direction (Lateral x), and the vertical axis represents the depth (Depth) z [mm]. As shown in FIG. 18, a focused echo image is obtained, and it can also be confirmed that the image is deflected.

  19 and 20 show the results of calculating the obtained deflection angle from the spectrum of the generated image signal. For this evaluation, the number of scatterers in the numerical phantom was increased, and 300 scatterers were randomly arranged at a depth of 0 to 40 mm. The reflection coefficient of each scatterer was set to a random value of −1 to 1. An error of 0.5 to 0.8 degrees was confirmed regardless of the set deflection angle. The error depends on the position of the scatterer relative to the generated wave. Increasing the number of scatterers improves accuracy (omitted).

  FIG. 21 shows the result of superposing a plurality of images obtained at different deflection angles. The deflection angle is set at 1 ° intervals, and 1 wave (0 °), 11 waves (−5 ° to 5 °), 21 waves (−10 ° to 10 °), and 41 waves (−20 ° to 20 °) Each was superimposed. FIG. 22 is a diagram in which the distribution in the horizontal direction of the point spread function estimated from the generated image signal is plotted. In FIG. 22, the horizontal axis represents the position [mm] in the horizontal direction (Lateral x), and the vertical axis represents the relative value of brightness (Brightness). As shown in FIG. 22, it can be confirmed that the resolution is improved as the number of superpositions is increased.

Migration method [Apply method (6) to beamforming during plane wave transmission with the same deflection]
FIG. 23 shows the result of generating the image signal by the migration method according to the present invention. The deflection angles were set to θ = 0 °, 5 °, 10 °, and 15 ° as in FIG.

(2) Deflection Monostatic Type Aperture Synthesis FIG. 24 shows a simulation result at the time of deflection by monostatic type aperture synthesis of method (2). Similarly to FIG. 18, the deflection angles were set to θ = 0 °, 5 °, 10 °, and 15 °. As shown in FIG. 24, it can be confirmed that an image is formed and deflected.

(3) Multistatic Type Aperture Synthesis FIG. 25 shows a simulation result by multistatic type aperture synthesis of method (3). FIG. 25 (a) shows a low resolution image generated using only signals received with the receiving element equal to the transmitting element (ie, one set) (ie, the same as the monostatic type). FIG. 25 (b) shows the result of superposing 33 sets of results in which the left and right 16 elements are used for reception in addition to the elements at the transmission position. FIGS. 25C and 25D show the result of superimposing 65 sets (32 elements on the left and right of the transmitting elements) and the result of overlapping 129 sets (64 elements on the left and right of the transmitting elements), respectively. As shown in FIG. 25, it can be confirmed that the image is formed. Moreover, the result of having plotted each point spread function is shown in FIG. From FIG. 25 and FIG. 26, it can also be confirmed that the side lobe is suppressed as the number of superimposed images increases, and the resolution is high.

(4) Fixed Focusing FIG. 27 shows the result of fixed focusing transmission. Here, method (1) was used. FIG. 27A shows the result of superimposing echo signals received at each transmission effective aperture and performing a single echo signal generation process. FIG. 27B shows a result of generating and superposing low-resolution echo signals for each effective aperture width. FIG. 27 (c) shows the result of generating and superposing echo signals with the same positional relationship in transmission and reception as a set, similar to multi-static aperture plane synthesis. As shown in FIG. 27, images are formed in any case, and no particular difference is seen.

(5) Generation of image signal in Cartesian coordinate system for transmission and reception in polar coordinate system (5-1) Cylindrical wave transmission Echo signal when transmitting ultrasonic wave from all elements of convex array simultaneously and transmitting cylindrical wave in frequency The result of processing in the area is shown in FIG. As shown in FIG. 28, it can be confirmed that the image is formed.

(5-2) Fixed Focusing FIG. 29 shows the result of processing a received signal that is fixedly focused at a depth of 30 mm using a convex array. FIG. 29A shows the result of superimposing the received signals obtained at each effective transmission aperture and performing one echo signal generation process, and FIG. 29B shows a low-resolution image for each transmission. The result of generating and overlaying is shown.

  The beam forming using the digital Fourier transform according to the present invention performed in the above simulation is based on the appropriate use of complex exponential multiplication and Jacobi calculation, and arbitrary beam forming processing in an arbitrary orthogonal coordinate system. It was proved that it can be realized with high accuracy without interpolation approximation. Any of the beam forming can be realized by using the DAS (Delay and Summation) method. However, the beam forming according to the present invention is speeded up by the difference between wave number matching and lateral Fourier transform, and can be used for a general purpose in a one-dimensional array. When a PC is used, the calculation time is significantly faster than 100 times. If the aperture elements form a two-dimensional or three-dimensional distribution, or a two-dimensional or three-dimensional array, the above method may be further increased in number of dimensions, and more processing can be performed than in the case of a one-dimensional case. This solves the problem that it requires, and the high speed becomes more effective. In addition, an example in which superposition or the like at the time of plane wave transmission with different deflection angles is effective has been described. The effect of increasing the resolution and increasing the contrast by suppressing the side lobes can be obtained at high speed.

  In the above example, it has been confirmed that arbitrary focus (including no focus) and steering can be performed in any array type aperture surface shape, and arbitrary beam forming processing in an arbitrary orthogonal coordinate system can be performed at high speed without interpolation approximation. It was confirmed that it could be realized with accuracy. The time for obtaining high-order measurement results such as displacement measurement based on the generated image signal is also shortened, and the effect of improving the measurement accuracy is also obtained.

  As described above, the example using the representative transducer, the reception sensor, the transmission unit and the reception unit, the control unit, the output device, the external storage device, and the like in the first embodiment has been described. The fact that the beam forming of the methods (1) to (7) was possible proved that arbitrary beam forming based on focusing and steering can be performed in an arbitrary orthogonal coordinate system, and the apparatus of the present invention. The beam forming and applications that can be realized using the above are not limited to those described in the others.

<< Second Embodiment >>
Next, configurations of a measurement imaging apparatus and a communication apparatus according to the second embodiment of the present invention will be described. FIG. 1 is a representative block diagram showing a configuration example when the device according to the first embodiment is an active type, and FIG. 2 is a representative block diagram showing a detailed configuration example of the device main body. However, in the second embodiment, a passive device is used. Therefore, the device according to the second embodiment does not include at least a transducer for transmission in FIG. 1, and further transmits from the control unit. It does not have a wired or wireless path for sending drive signals to the transducer.

  In the case of the active device according to the first embodiment, the detailed configuration example of the device and unit has been described with reference to FIGS. 1 and 2 as a representative configuration. However, the active device has an arbitrary opening shape. The transmission and reception transducer array devices (transducers may be used for both transmission and reception) are necessarily used, while passive devices are used in them in any shape of the transmission transducer array device. Do not use.

  In other words, the basic configuration of the apparatus according to the second embodiment includes a receiving transducer (or receiving sensor) 20, an apparatus main body 30, an input apparatus 40, an output apparatus (or display apparatus) 50, and an external storage device 60. Is provided. The apparatus main body 30 mainly includes a receiving unit 32, a digital signal processing unit 33, a control unit 34, and a storage unit (memory or storage device or storage medium) not shown. Furthermore, the apparatus main body 30 may include a transmission unit 31. The description of these components in the first embodiment is also applied to the second embodiment.

  As in the first embodiment, each of these devices and each unit in the device main body 30 can be installed at a remote location. The apparatus main body 30 is composed of a plurality of such units, and is referred to as such for convenience. Similarly to the first embodiment, reception may be performed by mechanically scanning the reception transducer 20. In general, even when not called an array type, the same processing may be performed.

  However, unlike the apparatus according to the first embodiment, the apparatus according to the second embodiment comes from an arbitrary wave source, as will be described in detail below, in order to sense the timing at which the wave is generated. The control unit senses the timing signal generated by receiving the observed wave itself or generates a timing signal through another process, via wired or wireless communication, and receives the data of each receiving unit (each receiving channel). It may be used as a trigger signal for starting (AD conversion and writing to memory).

  As a method for the control unit to sense a timing signal that informs the timing at which the wave is generated, when the wave itself coming from the wave source is used as the timing signal, the receiving transducer (or receiving sensor) of the apparatus according to the present embodiment The reception signal itself received by the 20 reception aperture elements 20a is used, or a timing signal received by a dedicated reception apparatus that may be provided in the apparatus main body 30 is used.

  In this case, the reception aperture element 20a (may be all elements, but the element or the like at the end or the center position may be used sparsely in the physical aperture) or a dedicated reception device (at least a plurality of reception channels). For example, information on the signal strength, frequency, band, code, etc. of the received signal through various input means as described above is detected. However, it is set to the control unit 34 (built-in memory) or an analog determination circuit (in this case, neither software nor hardware is variable and some hardware is fixed). Alternatively, the detection of the timing at which the wave is generated is performed by detecting the signal received by the receiving aperture element 20a or the dedicated receiving device in the memory or the storage device (storage medium), the threshold value, the value, and the characteristic of the wave to be observed. It is based on collating with discriminating data such as databases.

  In the case of discriminating the received signal in an analog manner, the trigger signal for data acquisition is generated only when the received signal is discriminated by a dedicated analog circuit provided, and only when the received signal is determined to be an observation target. There are cases where the beam forming process is performed after being converted and stored in a memory or a storage device (storage medium).

  When the received signal is digitally determined, the received signal is continuously AD-converted in time and stored in a memory or a storage device (storage medium). ) At a predetermined time interval (set through the input device, etc.), the digital signal processing unit 33 reads the stored signal and makes a determination based on the comparison with the determination data, and determines that the signal is an observation target signal. Only in such a case, the beam forming process may be performed.

  Since the storage capacity of the memory and the storage device (storage medium) is limited, the wave signal to be observed was not observed within a predetermined time (such as set through the input device) when digitally discriminating. In this case, the memory address is initialized. Further, although it is not efficient in terms of energy saving, the wave signal may be discriminated using the discrimination data based on the image signal that has been subjected to beam forming at any time and the accuracy has been improved by the beam forming. The processing is the same when a normal wave for communication purposes is an observation target.

  In addition, the dedicated receiving device may be installed at another position away from the units of other devices, for example, near the wave source to be measured, or at a position where the timing signal reception environment is good. There is a case where a wave propagating at a higher speed than a wave received at the receiving aperture (wave which becomes a timing signal) is used, and the timing signal is transmitted to the control unit in the apparatus body via the dedicated receiving apparatus. . A dedicated line (wired or wireless) that may use a relay station may be used. In this case, using the timing signal as a trigger signal, reception of the received signal (AD conversion and storage in a memory, a storage device, or a storage medium) and beam forming are performed.

  In addition, after the apparatus of the present invention receives a wave, a timing signal at which the wave is generated may arrive. In other words, the propagation speed is slow or such a mechanism may be used, but as a result, such a case may occur. In order to cope with such a case, the reception signal is constantly taken in, the reception signal stored in the memory or the storage device (storage medium) is read back in time, and beam forming is performed. . In that case, the timing signal is added with additional information on the wave obtained by other observers and observation devices as additional information at the relay station, etc., and the timing signal with additional information added is transmitted for dedicated reception. Information including additional information is read by the device and may be used not only in the device of the present invention but also in other devices. The line used is not limited to a dedicated line, and a normal network may be used. A similar timing signal may be used even when a wave for normal communication purposes is an observation target. The additional information may be transmitted by a wave or signal other than the timing signal.

  In addition to the generation of the wave to be observed, a wave that propagates at a higher or lower speed than the wave received by the receiving aperture element before, during, or after the generation (wave that becomes a timing signal) is a wave source. The dedicated receiving device and the dedicated line may be similarly installed and used. In that case, information about the wave to be observed may be added to the wave that becomes the timing signal, and information about the wave obtained by another observer or observation device is added by the relay station and transmitted. In some cases, information including additional information is read by the dedicated receiving device and used by the device of the present invention or other devices. The line used is not limited to a dedicated line, and a normal network may be used. A similar timing signal may be used even when a wave for normal communication purposes is an observation target. The additional information may be transmitted by a wave or signal other than the timing signal.

  As these dedicated receiving devices, dedicated sensing devices capable of sensing timing signals or reading additional information are used, but any observer or any observation device (observation object to be observed) can be used. Any active-type or passive-type observation device related to a wave or similar observation device, etc., or any other signal that is a precursor to the generation of the wave, is generated simultaneously with the wave, or is generated after the wave is generated Any active or passive observation device or similar observation device relating to the above phenomenon or wave) is used. In an irregular manner, only the timing signal is received by the dedicated receiving device, and the reading of the additional information itself may be performed by the digital signal processing unit via the dedicated device or the control unit in the device body.

  Even when the active or passive device itself of the present invention is used as a sensing device, the additional information may be read by the digital signal processing unit 33 in the same manner. As described above, the timing signal may be generated by the sensing device provided. When you don't know when, where, when, when, where, when and where the wave is generated, increase the efficiency of data acquisition and beam forming process, save power, memory and storage This is important for saving (storage media). Data capture and beam forming are performed based on the clock signal of the control unit 34. If the wave source is digital, it is better to synchronize and the device may operate at a high clock frequency and a high sampling frequency on the basis of analog reception of the wave to be observed. The same applies to the case where the timing signal is an analog signal. However, when the timing signal is a digital signal, synchronization may be obtained in the apparatus main body.

  The object of observation is the wave itself generated by a self-emanating wave source, the characteristics of the wave source (strength, what kind of source, etc.), position, time when the wave source was activated, etc. May be observed. Similarly to the case where the apparatus is an active type, the distribution of temperature (distribution), displacement, velocity, acceleration, strain, strain rate, or the like of the target may be obtained from the wave spectrum. In addition, the characteristics of the medium in the propagation process (propagation speed, physical properties related to waves, attenuation, scattering, transmission, reflection, refraction, etc., or their frequency dispersion) are observed, and the structure and composition of the observation target and medium May be revealed. For example, radioactive materials (such as isotopes in PET), materials with non-zero thermodynamic temperatures, seismic sources, neural activity, astronomical observations, weather, arrivals, moving objects, communication devices including mobile communication devices, physical Alternatively, an object that responds to chemical stimulation, an electric source, a magnetic source, a radiation source, or various energy sources are observed, and the observation target is not limited to these.

  Multiple different types of wave receiving transducers and sensors may be used to integrate measurement results (Fusion) and data mining through multi-physics or multi-chemistry. For example, when a plurality of compressed waves or shear waves arrive at the same time as dynamic waves, use an analog dedicated device using the mode, frequency, band, code, propagation direction, etc., or use a digital signal The beam forming may be performed after separating the waves using the processing unit as in the first embodiment. When there are a plurality of electromagnetic wave sources, a plurality of electromagnetic waves having different characteristics may be superimposed and may be separated in the same manner. Alternatively, a high-precision image signal may be generated even when a plurality of waves arrives due to the phasing addition effect by beam forming (for example, when the medium is a scattering medium).

  Of course, after beam forming is performed, signals may be separated based on the same processing. In order to obtain the effect of phasing addition, it is necessary to determine the arrival direction of the wave and the position of the wave source, and steering in that direction or focusing to the position may be performed. In reception, in addition to dynamic focusing, fixed focusing is also useful. In order to obtain them, the center-of-gravity (center) frequency, instantaneous frequency, band, so-called MIMO, SIMO, MUSIC, independent component analysis, code, various parametric methods, etc. of the wave received by the receiving aperture element array May be used. The same processing may be performed after performing beam forming, but in addition, waves may be observed using geometric information, particularly after performing beam forming at a plurality of positions. . The processing method is not limited to these, and may be implemented under an inverse problem approach, for example.

  For example, the propagation direction of an incoming wave is obtained based on multidimensional spectral analysis of the received signal (the past achievements of the first inventor of the present application), and the apparatus of the present invention is provided at different positions. Even when multiple transducers or reception effective apertures are not used to obtain information about propagation time (usually, the position and distance of the wave source are determined from the time at which waves were observed at multiple positions) It is possible to determine the position and distance of the wave source. Waves can be observed with continuous waves instead of pulse waves and burst waves. Through any processing, when the direction of arrival of the wave is known, the received beam can be steered and focused in that direction (monostatic or multistatic aperture synthesis) and observed in detail. If necessary, transmission beam forming may also be performed in the active type of the first embodiment. In those processes, receive beamforming is always performed while changing the steering angle, focusing on the likely direction, and the resulting image or imaging, spatial resolution, contrast, signal strength, etc. are observed, or The direction of the wave source can also be specified through multidimensional spectral analysis. It may be automatically controlled.

  The resolution of the image signal may be increased by super-resolution. It may be easy to measure the wave source, the object to be measured, scattering in the medium, the size, intensity, position, etc. of the reflector. Although the band is necessarily limited by the physically generated wave field, the super-resolution is to make the band wider by inverse filtering and restore them as an original signal source or signal. In addition, the wave is usually affected by frequency-dependent attenuation, may not be in focus, the wave source may be a moving object, and the intervening medium may be disturbed. . Super-resolution may be performed to correct these.

  In addition, the measurement target or the like may move during transmission and / or reception necessary for generating one image signal, and it may be necessary to perform motion compensation. In many cases, the point spread function is unknown, and in this case, blind deconvolution may be performed including the case where the above signal separation processing (particularly, blind separation) is used in combination. It is desirable to evaluate the point spread function by some method, and ideally to obtain a coherent point spread function, but even if the spectral distribution shape and band are obtained including the case obtained from the incoherent signal, inverse filtering is still possible Is possible.

  If the point spread function cannot be obtained when the observation is desired, for example, the point spread function may be evaluated and stored as a database when the observation is possible. One effective method for performing inverse filtering is to weight the observed spectrum so that it is identical to the desired spectral distribution of the point spread function. Alternatively, inversion can be performed using the power spectrum of the signal itself. These processes can be applied to the angular spectrum before wave number matching or the spectrum after wave number matching. That is, super-resolution can be performed using an angular spectrum or spectrum of a desired point spread function or an angular spectrum or spectrum of a received signal. It should be noted that in weighting, care must be taken when dividing by zero value or a small spectrum. In particular, it is not effective to amplify various noises included in the received signal, and regularization, singular value decomposition, etc. are effective. is there.

In the process of the digital wave signal processing (1) to (7), inverse filtering can be performed. The resolution of the image signal is increased, and an effect may be obtained in terms of quantitativeness (numerical value), but the same effect may be obtained when displayed as an image. Or blurred image is restored, the effect of focus or Tsu case is obtained. Inverse filtering may be performed on an incoherent signal, or it is effective when performed in the state of a coherent signal, and in particular, a spatial change of a physical property distribution may be understood. The application of super-resolution is not limited to these.

  In addition, detection is usually performed on the generated image signal, but in the frequency domain, calculation based on an angular spectrum or a conjugate product of the spectrum, and each wave number (frequency) before addition processing is also performed. Those operations on the components are also useful (one of the nonlinear processes in the present invention). Note that what is obtained through Fourier transform from an image signal obtained by beam forming (that is, focus and deflection realized by applying delay or apodization) is a spectrum, but further, beam forming is performed. In this case, the result of Fourier transform in the axial direction and at least one lateral direction is an angular spectrum. That is, after the image signal is generated, beam forming processing may be further performed.

  The operating mode may be determined by a command (signal) input to the apparatus. In addition, the wave to be observed (wave type and characteristics, intensity, frequency, bandwidth, sign, etc.) and propagating medium (propagation velocity, physical property value related to wave, attenuation, scattering, transmission, reflection, refraction, or , Their frequency dispersion, etc.) are given, and the received signal may be appropriately analog processed or digitally processed. The characteristics (intensity, frequency, bandwidth, code, etc.) of the generated image signal may be analyzed. Data obtained by the device according to the present embodiment may be used in other devices. The apparatus according to the present embodiment may be used as one of network devices, may be controlled by a network system control apparatus, and may be used as a control apparatus that controls the network device. In some cases, the control device controls a locally configured network.

  When the passive device according to the present embodiment is used as an active device, the transmission transducer (or applicator) 10 is connected to the transmission unit 31 of the device body 30, and the transmitter 31a is an analog device and is a trigger signal. If the control unit 34 generates and applies a trigger signal, or if the transmitter 31a has a mode in which the transmitter 31a operates in accordance with an external clock signal, any of the devices in the device main body 30 is provided. Or a clock signal from the control unit 34, or a mechanism in which the apparatus main body 30 operates with the clock signal of the transmitter 31a may be provided. In the case where the transmitter 31a is a digital device, the transmission and reception clock signals are synchronized by any one of these mechanisms. This is important when one image signal is generated based on a plurality of transmissions. If synchronization cannot be achieved, errors may be reduced in situations where the clock frequency or sampling frequency is high.

  As described above, arbitrary beam forming can be realized by digital processing without performing high-speed interpolation approximation through fast Fourier transform. Virtually any focusing and any steering (deflection) can be performed using a transducer array device with any aperture shape. The second embodiment can be used in an ordinary apparatus as an apparatus and with respect to an operation mode (for example, an imaging mode, a Doppler mode, a measurement mode, a communication mode, etc.), and those and the above-described ones. It is not limited to.

  In the first and second embodiments described above, for electromagnetic waves, vibration waves (mechanical waves) including acoustic waves (compression waves), shear waves, shock waves, surface waves, etc., or waves such as heat waves, Regardless of transmission / reception focusing, transmission / reception steering, transmission / reception apodization or not, any beamforming is digitally performed, including the case where the coordinate system for transmitting / receiving and the coordinate system for generating the beamformed signal are different. It can be carried out with high accuracy and at high speed without performing interpolation approximation based on the processing. Not only the frame rate when displaying the beam-formed signal is improved, but also high spatial resolution and high contrast can be obtained with respect to image quality, and further, displacement and deformation using the beam-formed signal, or Measuring temperature etc. will improve measurement accuracy. The application of the present invention is not limited to this. The high speed of processing has a great effect in multidimensional imaging using a multidimensional array. The present invention is not limited to the above-described embodiments, and many modifications can be made within the technical idea of the present invention by those having ordinary knowledge in the technical field.

  There are various measurement objects such as organic substances, inorganic substances, solids, liquids, gases, objects that follow rheology, living creatures, astronomical objects, the earth, and the environment, and the application range is extremely wide. Contribute to nondestructive testing, diagnosis, resource exploration, material and structure generation and manufacturing, physical and chemical restoration and treatment monitoring, and application of revealed functions and physical properties. However, there is a case where accuracy is required under conditions that are not invasive, minimally invasive, and noninvasive, without causing great disturbance to the measurement target. Ideally, the object may be observed in situ in situ. In addition, treatment or repair may be performed on the target by the action of the wave itself, and the situation may be observed by performing beam forming on the response from the target at that time. Also, beam forming is performed in satellite communication, radar, sonar, etc., and an energy-saving and information-safe environment is realized, and accurate communication is possible. The present invention is also effective in normal communications including ad hoc communication devices and mobile devices. It can also be applied to sensor networks. When the object is dynamic, real-time characteristics are required. However, according to the present invention, digital beam forming can be completed quickly and with high accuracy in a short time.

The present invention, beamforming method for performing beamforming using any wave coming from instrumentation points, and can be utilized in measuring the imaging device and a communication device using such a beam forming method.

  Generation of wave signals such as radar, sonar, other optical waves, sound waves, heat waves, etc. is often already generated by digital devices, and it is highly aimed at applying the signals. It can be applied in conjunction with signal generation only by providing processing capability for performing the next calculation. The multi-dimensionalization of various devices is also being attempted, and the importance of the present invention will increase. Measurement objects are solid, fluid, rheology, inorganic, organic, creatures, environments, etc., and the measurement range is expected to expand. In the future, miniaturization of each device in the device will further progress, and the calculation stress will be sufficiently high, and it will be possible to incorporate a computer at a lower cost, and many useful devices with real time will be realized. We can expect to go. In addition to the simple wave imaging device, the development of applications through measurement using waves will become more popular and the application range will be broadened. The digitization of various devices is expected to progress further in the future, and at that time, it is considered that the demand for high-precision and high-speed beam forming capable of generating a high-precision signal according to the present invention in real time will increase. After all, in addition to being fast, there is no need to perform the necessary interpolation approximation so far. It is also an effective device for normal communications and sensor networks. The applicability and marketability of digital beamforming according to the present invention based on digital signal processing is much higher.

  DESCRIPTION OF SYMBOLS 10 ... Transmission transducer (or applicator), 10a ... Transmission aperture element, 20 ... Reception transducer (or reception sensor), 20a ... Reception aperture element, 30 ... Apparatus main body, 31 ... Transmission unit, 31a ... Transmitter, 32 ... Reception Unit, 32a ... receiver, 32b ... AD converter, 32c ... memory (or storage device or storage medium), 33 ... digital signal processing unit, 34 ... control unit, 35 ... reception unit (or reception device), 35a ... reception 35b ... AD converter, 35c ... memory (or storage device or storage medium), 35d ... phasing adder, 35e ... other data generator, 40 ... input device, 50 ... output device, 60 ... external storage device

Claims (47)

In Cartesian rectangular coordinate system using the coordinates of the transverse direction x of the axial direction y and perpendicular thereto determined by the opening direction of the receiving opening element array, any wave toward a measurement object from the wave source located in an arbitrary direction sent, when receiving processing a wave coming from the measurement object as a plane wave, in the case where the deflection angle of zero degree or non zero formed by the reception and axial direction of the plane wave is expressed by the deflection angle theta,
Receiving a wave coming from the measurement object by at least one receiving aperture element to generate a received signal;
Performing a beam forming process by performing at least Fourier transform and wave number matching on the reception signal generated in step (a); and
Comprising
Step (b)
The received signal is expressed by using the wave number k and the imaginary unit i of the wave as a result of Fourier transform with respect to the axial direction y without performing wave number matching including interpolation approximation processing in the wave number domain or frequency domain. By multiplying the complex exponential function (101)
Further, the product is Fourier transformed with respect to the lateral direction x to have a resolution with respect to the axial direction y, and a complex exponential function that can be implemented without the effect of wave number matching performed in the lateral direction x is obtained. 102) and a complex exponential function (103) to perform wavenumber matching in the axial direction, where the transverse wavenumber is represented as k _x ,
A beam forming method including generating an image signal directly in a Cartesian rectangular coordinate system by performing wave number matching without performing interpolation approximation processing. In Cartesian rectangular coordinate system using the coordinates of the transverse direction x and z to the axial direction y and perpendicular thereto determined by the direction of the opening of the receiving aperture element array, any toward the measurement object from the wave source located in an arbitrary direction wave is transmitted, the table the wave coming from the measurement object when receiving processed as a plane wave, the deflection angle of zero degree or non zero formed by the receiving direction and the axial direction of the plane wave with the elevation θ and azimuth angle φ In the case where
Receiving a wave coming from the measurement object by at least one receiving aperture element to generate a received signal;
Performing a beam forming process by performing at least Fourier transform and wave number matching on the reception signal generated in step (a); and
Comprising
Step (b)
The received signal is expressed by using the wave number k and the imaginary unit i of the wave as a result of Fourier transform with respect to the axial direction y without performing wave number matching including interpolation approximation processing in the wave number domain or frequency domain. By multiplying the complex exponential function (201)
Further, the product can be subjected to Fourier transform with respect to the lateral directions x and z so as to have a resolution with respect to the axial direction y, and the obtained calculation result can be performed without the effect of wave number matching performed in the lateral directions x and z. with multiplying the complex exponential function (202), the wavenumber matching the axial direction by applying a complex exponential function (203), wherein the wave number of the horizontal direction is represented by k _x and k _z,
A beam forming method including generating an image signal directly in a Cartesian rectangular coordinate system by performing wave number matching without performing interpolation approximation processing.   Prior to step (a), the method further comprises the step (a ′) of transmitting a wave having a declination angle or elevation angle and azimuth angle of zero degrees or non-zero degrees from at least one transmission aperture element toward the measurement object. The beamforming method according to claim 1 or 2. The step (a ') of transmitting an unfocused wave from at least one transmission aperture element toward the measurement object prior to step (a) is further provided. Beam forming method. Using mechanical scanning or coordinate in the lateral direction x orthogonal axial y and to determined the electronic scanning by the direction of the opening of the line the Hare receive effective aperture element array, the y coordinate of the zero position of the received effective aperture array A beam forming method for performing monostatic aperture synthesis to generate a beam subjected to dynamic focusing for transmission and reception in a Cartesian Cartesian coordinate system having zero or non-zero degrees formed by an axial direction and the beam direction. In the case where the deflection angle is expressed by the deflection angle θ,
Transmitting a wave from the transmission aperture element toward the measurement object (a ′);
Receiving a wave coming from the measurement object by one of a plurality of receiving aperture elements at different positions to generate a received signal;
(B) performing a monostatic type aperture surface synthesis process having a zero or non-zero degree declination θ by performing at least Fourier transform on the reception signal generated in step (a);
Comprising
In step (a ′), the wave is generated by at least reflection or backscattering in the measurement object, or is generated by at least transmission, forward scattering, or refraction in the measurement object. Similarly, each of the plurality of transmission aperture elements having the same x coordinate as the reception aperture element that generates the reception signal and further having the zero y coordinate, and also serving as the plurality of reception aperture elements, or Transmitting a wave from each one of a plurality of transmission aperture elements having a non-zero constant y coordinate and facing the plurality of reception aperture elements;
Step (b)
In the wave number domain (k _x , k _y ) where the wave numbers in the axial direction y and the lateral direction x are k _y and k _x , respectively, wave number matching including interpolation approximation processing in the wave number domain or frequency domain is performed on the received signal. Without using the wave vector (sk ₀ sinθ, sk ₀ cos θ) with respect to the wave vector (0, k ₀ ) having the wave number k ₀ (= ω ₀ / c) expressed using the wave carrier frequency ω _0. In order to perform transmit and receive dynamic focusing with spectral shifting to produce an image signal with a centroid or instantaneous frequency of the multidimensional spectrum,
A parameter s having a value of 2 when the y-coordinate of the transmission aperture element is zero and a value of 1 when the y-coordinate of the transmission aperture element is non-zero. By multiplying the center of gravity frequency k _{0 of the} wave and the complex exponential function (301) expressed using the imaginary unit i, wave number matching in the lateral direction x is performed,
Further, the product is Fourier transformed with respect to the lateral direction x to have a resolution with respect to the axial direction y, and a complex exponential function that can be implemented without the effect of wave number matching performed in the lateral direction x is obtained. 302) and wavenumber matching in the axial direction by multiplying the complex exponential function (303),
A beam forming method including generating an image signal directly in a Cartesian rectangular coordinate system by performing wave number matching without performing interpolation approximation processing. With axial y and transverse x and z coordinates perpendicular thereto determined by the opening direction of the mechanical scanning or electronic scanning lines earthenware pots receive effective aperture array, y of zero position of the received effective aperture array In a Cartesian Cartesian coordinate system having coordinates, a beamforming method that performs monostatic aperture synthesis to generate a beam subjected to dynamic focusing of transmission and reception, wherein the axial direction and the beam direction have zero degrees or In the case where the non-zero deflection angle is expressed using the elevation angle θ and the azimuth angle φ,
Transmitting a wave from the transmission aperture element toward the measurement object (a ′);
Receiving a wave coming from the measurement object by one of a plurality of receiving aperture elements at different positions to generate a received signal;
(B) performing monostatic aperture plane synthesis processing having an elevation angle θ and an azimuth angle φ of zero or non-zero degrees by performing at least Fourier transform on the reception signal generated in step (a); ,
Comprising
In step (a ′), the wave is generated by at least reflection or backscattering in the measurement object, or is generated by at least transmission, forward scattering, or refraction in the measurement object. Similarly, each of the plurality of transmission aperture elements having the same x coordinate and z coordinate as the reception aperture element that generates the reception signal, and also having the zero y coordinate, and also serving as the plurality of reception aperture elements Or transmitting a wave from each of a plurality of transmission aperture elements having a non-zero constant y coordinate and facing the plurality of reception aperture elements,
Step (b)
In the wave number regions (k _x , k _y , k _z ) where the wave numbers in the axial direction y and the lateral directions x and z are k _y , k _x , and k _z , respectively, the wave number region or the frequency region with respect to the received signal For wave vector (0, k ₀ , 0) having wave number k ₀ (= ω ₀ / c) expressed using wave carrier frequency ω ₀ without performing wave number matching including interpolation approximation processing in In order to perform dynamic focusing of transmission and reception with spectrum shifting to generate an image signal having a wave vector (sk ₀ sin θ cos φ, sk ₀ cos θ, sk ₀ sin θ sin φ) as the center of gravity or instantaneous frequency of a multidimensional spectrum,
A parameter s having a value of 2 when the y-coordinate of the transmission aperture element is zero and a value of 1 when the y-coordinate of the transmission aperture element is non-zero. Multiply the complex exponential function (401) expressed using the centroid frequency k _{0 of the} wave and the imaginary unit i to perform wave number matching in the lateral directions x and z,
Further, the product can be subjected to Fourier transform with respect to the lateral directions x and z so as to have a resolution with respect to the axial direction y, and the obtained calculation result can be performed without the effect of wave number matching performed in the lateral directions x and z. Multiplying the complex exponential function (402) and the complex exponential function (403) to perform wave number matching in the axial direction,
A beam forming method including generating an image signal directly in a Cartesian rectangular coordinate system by performing wave number matching without performing interpolation approximation processing. In mechanical scanning or Cartesian rectangular coordinate system using the coordinates of the transverse direction x of the axial direction y and perpendicular thereto determined electronic scanning by the direction of the opening of the line the Hare receive effective aperture element array, at least receive dynamic focusing is performed A beam forming method that performs multi-static aperture surface synthesis for generating a beam, and a zero-degree or non-zero degree deflection angle formed by an axial direction and the beam direction is represented by an angle θ,
Transmitting a wave from the transmission aperture element into the measurement object (a ′);
Receiving a wave coming from the measurement object by at least one of a plurality of reception aperture elements at different positions to generate a reception signal;
(B) performing a multi-static aperture surface synthesis process having a zero or non-zero degree deflection angle θ by performing at least Fourier transform on the reception signal generated in step (a);
Comprising
In step (a ′), the wave is generated by at least reflection or backscattering in the measurement object, or is generated by at least transmission, forward scattering, or refraction in the measurement object. Similarly, any reception aperture element in the reception effective aperture element array having an arbitrary x coordinate irrespective of the x coordinate of the reception aperture element that generates the reception signal and further having a zero y coordinate 1 or a plurality of transmission aperture elements different from any of the reception aperture elements, or a transmission effective aperture at a position facing the reception effective aperture element array having a non-zero constant y coordinate. Transmitting a wave from each of a plurality of transmit aperture elements in the element array;
When the y-coordinate of the transmission aperture element is zero for each reception signal group obtained by arranging the reception signals having the same distance Δx in the lateral coordinate between the transmission position and the reception position in step (b), The transmission aperture element represented by using the y-coordinate of the point of interest including the position of the transmission aperture and the distance Δx, and a half distance of a straight line connecting the point of interest and the reception aperture element, or of the transmission aperture element When the y coordinate is non-zero, the distance between the transmission aperture element, the point of interest, and the reception aperture element expressed using the y coordinate of the point of interest, the y coordinate of the transmission aperture element, and the distance Δx is used. Te, each of image signals obtained by setting the deflection angle in the monostatic synthetic aperture in the beam forming method according to claim 5 corrected for lateral position in the frequency domain, interpolation approximation processing by superimposing them And generating an image signal without performing beamforming method. In mechanical scanning or Cartesian rectangular coordinate system using the coordinates of the transverse direction x and z orthogonal axial y and to determined the electronic scanning by the direction of the opening of the line the Hare receive effective aperture element array, at least receive dynamic focusing of facilities A beam forming method for synthesizing a multi-static aperture plane that generates a focused beam, and a zero or non-zero deflection angle formed by the axial direction and the beam direction is expressed using an elevation angle θ and an azimuth angle φ. When
Transmitting a wave from the transmission aperture element into the measurement object (a ′);
Receiving a wave coming from the measurement object by at least one of a plurality of reception aperture elements at different positions to generate a reception signal;
A step of performing a multistatic type aperture plane synthesis process having an elevation angle θ and an azimuth angle φ, which are deflection angles of zero or non-zero degrees, by performing at least Fourier transform on the reception signal generated in step (a). (B) and
Comprising
In step (a ′), the wave is generated by at least reflection or backscattering in the measurement object, or is generated by at least transmission, forward scattering, or refraction in the measurement object. Similarly, in the reception effective aperture element array, which has an arbitrary x coordinate and z coordinate irrespective of the x coordinate and the z coordinate of the reception aperture element that generates the reception signal, and further has a zero y coordinate. Either one of the plurality of transmission aperture elements that doubles as one of the reception aperture elements, or opposite to the reception effective aperture element array having a non-zero constant y coordinate. Transmitting a wave from each one of a plurality of transmit aperture elements in a transmit effective aperture element array at a location;
For each received signal group obtained by arranging the received signals having the same distances Δx and Δz in the lateral x-coordinate and z-coordinate between the transmitting position and the receiving position in step (b), y of the transmission aperture element is obtained. When the coordinate is zero, the transmission aperture element represented by using the y coordinate of the point of interest including the transmission aperture position and the distances Δx and Δz and half the linear distance connecting the point of interest and the reception aperture element When the distance or the y-coordinate of the transmission aperture element is non-zero, the transmission aperture element represented by using the y-coordinate of the point of interest, the y-coordinate of the transmission aperture element, and the distances Δx and Δz, and the point of interest using the distance between the receiving aperture element, corrected for lateral position in each of the frequency domain of the image signal obtained by setting the deflection angle in the monostatic synthetic aperture in the beam forming method according to claim 6 They were the superimposing includes generating the image signal without performing the interpolation approximation process, beam forming method. In order to generate an image signal representative of the propagation of unknown wave source or wave it generates, step (a ') is, by setting the unknown y-coordinate of the wave source which is estimated to y coordinate of the transmission aperture element, The beamforming method according to any one of claims 5 to 8 , comprising performing beamforming. In Cartesian rectangular coordinate system using the coordinates of the transverse direction x of the axial direction y and perpendicular thereto determined by the direction of the opening of the receiving aperture element array to generate an applied beam of transmission focusing fixed by any wave source, In the case where a zero degree or non-zero degree deflection angle formed by the axial direction and the beam direction is expressed by an angle θ,
Waves arriving from the measurement object are received by a plurality of reception effective aperture arrays including a plurality of reception aperture elements at different positions set in the physical aperture, and a reception signal is generated by each reception effective aperture array. Step (a);
Performing a fixed focusing beamforming process for forming a beam having a deviation angle θ of zero degrees or non-zero degrees by performing at least Fourier transform on the reception signal generated in step (a);
Comprising
For step (b), the received signal generated in step (a)
(I) One reception signal composed of superposition of reception signals generated by reception aperture elements at the same position of the plurality of reception effective aperture element arrays, by superimposing reception signals generated by these reception aperture elements. Obtaining a group and performing one image signal generation process using the beamforming method according to claim 1 or 7 ,
(Ii) For each reception signal generated by the plurality of reception effective aperture element arrays each time one fixed focus beam is transmitted, a low-resolution image signal is generated using the beam forming method. Superimposing them,
(Iii) An image signal is generated using the beamforming method as an echo group having the same distance between each transmission aperture element in the effective transmission aperture element array and each reception aperture element in the reception effective aperture element array. And superimposing
A beamforming method including generating an image signal without performing an interpolation approximation process based on any one of the processes. In Cartesian rectangular coordinate system using the coordinates of the transverse direction x and z to the axial direction y and perpendicular thereto determined by the direction of the opening of the receiving aperture element array, generating a decorated beam of transmission focusing fixed by any wave source In the case where the deflection angle of zero degree or non-zero degree formed by the axial direction and the beam direction is expressed using the elevation angle θ and the azimuth angle φ,
Waves arriving from the measurement object are received by a plurality of reception effective aperture arrays including a plurality of reception aperture elements at different positions set in the physical aperture, and a reception signal is generated by each reception effective aperture array. Step (a);
Step (b) of performing a fixed focusing and beam forming process for forming a beam having an elevation angle θ and an azimuth angle φ of zero or non-zero degrees by performing at least Fourier transform on the reception signal generated in step (a) )When,
Comprising
For step (b), the received signal generated in step (a)
(I) One reception signal composed of superposition of reception signals generated by reception aperture elements at the same position of the plurality of reception effective aperture element arrays, by superimposing reception signals generated by these reception aperture elements. Obtaining a group and performing one image signal generation process using the beamforming method according to claim 2 or 8 ,
(Ii) For each reception signal generated by the plurality of reception effective aperture element arrays each time one fixed focus beam is transmitted, a low-resolution image signal is generated using the beam forming method. Superimposing them,
(Iii) An image signal is generated using the beamforming method as an echo group having the same distance between each transmission aperture element in the transmission effective aperture element array and each reception aperture element in the reception effective aperture element array. And superimposing
A beamforming method including generating an image signal without performing an interpolation approximation process based on any one of the processes. Beam or wave transmission and reception, have different deflection angles in transmission and reception, beamforming method according to any one of claims 1 to 11. As at least one transmission aperture element or at least one receiving aperture element, made of a plurality of aperture element for transmitting or receiving waves is used, a beamforming method according to any one of claims 1 to 12. Before being used KiHiraki opening element array, the reception of the wave is, the receiving opening element 2-dimensional Cartesian orthogonal coordinate system using the coordinates of the transverse direction x or z perpendicular axial direction y and thereto determined by the orientation of the array of openings ( x, y) or in a three-dimensional Cartesian Cartesian coordinate system (x, y, z), and the received signal of the received wave is expressed as r (x, y) or r (x, y, z) In order to implement the beamforming method according to any one of claims 1 to 13 , step (b) is based on a predetermined migration method,
The wave number domain or frequency domain of the Cartesian Cartesian coordinate system (k _x , which is obtained by two-dimensional or three-dimensional Fourier transform without performing wave number matching including interpolation approximation processing in the wave number domain or frequency domain on the received signal. For the angular spectrum R "(k _x , k) or R" (k _x , k, k _z ) expressed using the wave number k of the wave in (k _y ) or (k _x , k _y , k _z ), To calculate an integral of the type represented by equation (501),
After adding the wave number k component or frequency component of the angular spectrum, the inverse Fourier transform is performed on the wave number k _x or k _z in the horizontal direction, and wave number matching is performed without performing interpolation approximation processing. A beamforming method comprising generating an image signal directly in a Cartesian Cartesian coordinate system. Step (b) performs the inverse Fourier transform on the horizontal direction after performing the above wave number matching for each wave number k with respect to arbitrary coordinates in the axial direction y, and then adding all of the results. The beamforming method according to any one of claims 1 to 14 , comprising generating an image signal directly in a Cartesian Cartesian coordinate system. Step (b) comprises the arbitrary coordinate axial y, the inverse Fourier transform about the transverse direction of the to calculate the sideways direction of the coordinates is limited to an arbitrary coordinate or any range, claims The beam forming method according to any one of 1 to 15 . The beamforming method according to any one of claims 1 to 16 , wherein when wave reception is performed in an orthogonal curve coordinate system, beamforming is similarly performed using the coordinate axes of the coordinate system. By Jacobi calculation, image signal is generated directly in Cartesian coordinate system or Cartesian coordinate system which is the Cartesian Cartesian coordinate system or Cartesian coordinate system where wave is received without performing interpolation approximation process. is the beamforming method according to any one of claims 1 to 17. When the reception aperture element array has a circular shape, wave reception is performed in a two-dimensional polar coordinate system (r, θ), and a received signal of the received wave is expressed as f (r, θ). In step (b), a Cartesian rectangular coordinate system is obtained by a two-dimensional Fourier transform performed on the received signal f (r, θ) to decompose the received wave into a plane wave in the Cartesian rectangular coordinate system (x, y). Expression (601) expressed in the wave number domain or frequency domain (k _x , k _y ) of ( _x , _y ) is converted into the expression (602) by Jacobi calculation using x = rsinθ and y = rcosθ. Calculate as
The beamforming method according to any one of claims 1 to 18 , comprising generating an image signal directly in a Cartesian orthogonal coordinate system without performing an interpolation approximation process. When the receiving aperture element array has a spherical shape, the wave is received in the spherical coordinate system (r, θ, φ), and the received signal of the received wave is expressed as f (r, θ, φ). When step (b) is performed on the received signal f (r, θ, φ) to decompose the received wave into plane waves in a Cartesian Cartesian coordinate system (x, y, z) Expression (701) expressed in the wave number domain or the frequency domain (k _x , k _y , k _z ) of the Cartesian Cartesian coordinate system (x, y, z) by the transformation is expressed by x = rsinθcosφ, y = rcosθ, and Using the Jacobian calculation using z = rsinθsinφ, the calculation is performed as in equation (702).
The beam according to any one of claims 2 to 4, 6, 8, 9, and 11 to 18, comprising generating an image signal directly in a Cartesian rectangular coordinate system without performing an interpolation approximation process. Forming method. As the information on the wave source position or the transmission aperture element, the position with respect to the reception aperture element, the direction or distance of the existing position, the direction of the aperture, or the propagation direction of the generated wave is given, and beam forming is performed according to the information. The beamforming method according to any one of claims 1 to 20 . The beamforming method according to any one of claims 1 to 20 , wherein a time at which a wave is generated by an arbitrary wave source is given, and beamforming is performed according to the time. When the received signal includes a plurality of received signals generated wave from different wave sources, performs beamforming with a deflection angle of the propagation direction of the wave to be observed, in any one of claims 1 to 20 The described beamforming method. When the received signal includes a plurality of received signals of waves generated from a plurality of different wave sources, the center-of-gravity frequency, instantaneous frequency, bandwidth, MIMO (Multiple-input and Multiple-output), MIMO (Single-output) input and Multiple-output), MUSIC (Multiple signal Classification), independent component analysis, code, or to separate the signals on the basis of various parametric method, beam forming is carried out, any one of claims 1 to 20 The beam forming method described in 1. When the received signal includes a plurality of received signals of waves generated from a plurality of different wave sources, the centroid frequency, instantaneous frequency, band of multidimensional spectrum for the image signal obtained using the beam forming method, Signals are separated based on MIMO (Multiple-input and Multiple-output), SIMO (Single-input and Multiple-output), MUSIC (Multiple Signal Classification), independent component analysis, code, or various parametric methods. forming is performed, the beam forming method according to any one of claims 1 to 20. FIG. For the received signal, obtains the center of gravity or the instantaneous frequency of the multi-dimensional spectrum, than this, obtains the propagation direction of the wave motion, by adjusting the deflection angle of transmission or reception, beamforming is performed, according to claim 1 to 20 The beam forming method according to any one of the above. Against the beamformed image signals generated by, we obtain the center of gravity or the instantaneous frequency of the multi-dimensional spectrum, than this, obtains the propagation direction of the wave motion, by adjusting the deflection angle of transmission or reception, beamforming row The beam forming method according to any one of claims 1 to 20 . The process of obtaining the propagation direction of wave movement performed for a plurality of receiving openings or receiving effective opening, geometrically determine the direction of propagation of the wave, beamforming method according to claim 26 or 27. Super-resolution is performed on the angular spectrum before wave number matching or the spectrum after wave number matching obtained from the received signal using the angular spectrum or spectrum of the desired point spread function or the angular spectrum or spectrum of the received signal. The beam forming method according to any one of claims 1 to 20 . Coordinates represented by an arbitrary wave source by rotating or spatially shifting a Cartesian Cartesian coordinate system or Cartesian coordinate system, which is a Cartesian curve coordinate system, determined by the receiving aperture element array. 30. The beamforming method according to any one of claims 1 to 29 , wherein when generated in the system, the beamforming is performed after correcting the coordinates of the received signal. Coordinates represented by an arbitrary wave source by rotating or spatially shifting a Cartesian Cartesian coordinate system or Cartesian coordinate system, which is a Cartesian curve coordinate system, determined by the receiving aperture element array. when produced in the system, on the transmission beam forming with the conversion of the coordinate system determined by the receiving aperture array was rows, reception beam forming is performed, according to any one of claims 1 to 30 Beam forming method. The beamforming method according to any one of claims 1 to 31 , wherein the wave is at least one of an arbitrary electromagnetic wave, an arbitrary mechanical wave, and an arbitrary thermal wave. The beamforming method according to any one of claims 1 to 32 , wherein the received wave is a type of wave that is physically different from the wave transmitted to the measurement object. In correcting inhomogeneity of the propagation speed of the wave movement, the phase aberration correction is performed on the received signal, beamforming method according to any one of claims 1 to 33. Physical wave source, transmission aperture element, or the received signal with respect to a virtual wave source or virtual detection aperture device and a receiving aperture element are set separately is processed, either of claims 1 to 34 1 The beam forming method according to item. When multiple waves are received at the same time in the same time phase, at different times, or at substantially the same time phase, they are overlapped or overlapped in the spatial domain before Fourier transform or, before performing the inverse Fourier transform, or multidimensional spectra of each wave are superimposed in the frequency domain or frequency domain, or, characterized in that it is superimposed claim 1-35 2. The beam forming method according to item 1. The beamforming method according to any one of claims 1 to 36 , wherein only a spectrum of a predetermined band in a wave number domain or a frequency domain is processed. The beamforming method according to any one of claims 1 to 37 , wherein the predetermined linear calculation process is replaced with a non-linear calculation process. The beamforming method according to any one of claims 1 to 38 , wherein the Fourier transform includes a fast Fourier transform.   The beamforming method according to claim 1 or 2, comprising performing a fast Fourier transform that directly generates a result obtained by multiplying a Fourier transform of the time of the received signal by a complex exponential function (101) or (201). . 41. The beamforming method according to any one of claims 1 to 40 , comprising performing parallel processing in order to shorten the calculation time. Step (b), instead of the received signal generated in step (a), comprises performing a beam forming process on the image signal after generating the image signal, claim 1-41 2. The beam forming method according to item 1. At least one receiving aperture element for receiving a wave coming from a measurement object and generating a received signal;
A digital signal processing unit that performs an operation to generate an image signal by performing the beamforming method according to any one of claims 1 to 42 on the generated reception signal;
A device comprising: 44. The apparatus of claim 43 , further comprising at least one transmission aperture element that transmits a wave toward the measurement object. 45. The apparatus according to claim 43 or 44 , further comprising a phase aberration correction unit that corrects inhomogeneity of a propagation speed of a transmitted wave. Cartesian coordinate system that is Cartesian Cartesian coordinate system or Cartesian curve coordinate system that is determined by the direction of the aperture of the receiving aperture element array when the coordinate system where transmit beam forming is performed is Cartesian coordinate system or Cartesian coordinate system 43. An apparatus comprising a digital signal processing unit that performs an operation of generating an image signal by performing the beam forming method according to any one of claims 1 to 42 in an orthogonal coordinate system in which the transmission beam forming is performed instead of a system. . An operation is directly performed on the image signal in a Cartesian coordinate system or Cartesian coordinate system in which the image signal is generated by performing the beam forming method according to any one of claims 1 to 42 , or Alternatively, through interpolation processing, the image signal represented by an orthogonal coordinate system different from the Cartesian coordinate system that is the Cartesian coordinate system or the orthogonal curve coordinate system in which the image signal is generated is subjected to computation, and another wave of the observation target A device comprising a digital signal processing unit for calculating any one of propagation, displacement, velocity, acceleration, strain, strain rate, temperature, and characteristics.