JP4252252B2 - Imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging apparatus that images and detects a target object by radiated electromagnetic waves.
[0002]
[Prior art]
An imaging device is a device that detects an image formed by collecting electromagnetic waves radiated and reflected from a subject using an imaging lens.
The image obtained by this apparatus is used to detect a target from the background, for example. At this time, the one having a larger contrast between the target and the background can be easily distinguished. Since the brightness of the image increases in accordance with the amount of incident electromagnetic waves, when the difference in the amount of incident light between the target and the background is small, the contrast becomes small, making it difficult to detect the target.
As a means for increasing the contrast between the target and the background even when there is no difference in the amount of incident electromagnetic waves, the use of polarization characteristics can be mentioned.
[0003]
FIG. 22 is an optical path diagram of the imaging apparatus described in Japanese Patent Application Laid-Open No. 62-259112.
In this figure, 2a is a transmitted light imaging lens that collects an electromagnetic wave from a target that is a subject to form an image, and 3 is a detector that detects an image obtained by the transmitted light imaging lens 2a and converts it into an electrical signal. Reference numeral 4 denotes a signal processing device for processing a signal from the detector 3.
A polarizing filter 19 is provided on the target side of the transmitted light imaging lens 2a and plane-polarizes by absorbing a polarized light component orthogonal to the incident light beam. A rotating device 20 houses a deflecting filter 19 therein. Has a function to rotate.
In the figure, an arrow symbol indicates a polarization direction in which the vibration direction of the electromagnetic wave is parallel to the ground plane, and a symbol indicated by a cross in a circle indicates a polarization direction in which the vibration direction of the electromagnetic wave is orthogonal thereto.
[0004]
The polarization characteristics of the target and the background are generally different due to differences in physical properties such as the material and surface state.
For example, if infrared rays are used as electromagnetic waves, the target is an object that can be regarded as a black body, and the background is a water surface that reflects sunlight, the infrared rays from the target do not have a specific polarization plane, whereas the reflected infrared rays from the background Is partially polarized in one direction. Therefore, before the infrared rays reach the detector 3, the reflected infrared rays from the partially polarized background are attenuated by the polarizing filter 19 so that the orthogonal polarization components are increased, so that the contrast with the target is increased.
[0005]
In this example, since the polarization plane of the reflected infrared rays from the background is unknown in advance, as shown in FIG. 23, the polarization filter 19 is rotated by driving the rotating device 20 and is attenuated by averaging over time.
A device for detecting the polarization plane of reflected infrared light from the background is provided, and the polarization filter 19 is rotated so as to be substantially perpendicular to the polarization plane of the background detected by the device, thereby reducing the amount of reflected infrared light from the background. You may do it.
[0006]
In order to perform target detection based on the difference in polarization characteristics, the degree of polarization, which is a parameter indicating the magnitude of polarization, may be used.
According to “Optical Technology Handbook” Asakura Shoten (1997.4.1) and the like, the degree of polarization P of partially plane-polarized light is orthogonal to the maximum intensity Imax transmitted through the rotating polarizing filter 19. The degree of polarization P = (Imax−Imin) / (Imax + Imin) is obtained from the minimum value Imin which is a component of plane polarized light. That is, by rotating the polarization filter 19, as shown in FIG. 23, the output with respect to the rotation of the polarization filter 19 fluctuates, and by calculating the polarization degree P from the value, the difference in the polarization characteristics between the target and the background can be obtained. Appears and the contrast between the two can be increased.
[0007]
[Problems to be solved by the invention]
In the conventional image pickup apparatus as described above, it is necessary to rotate the polarization filter 19 in order to make the polarization filter 19 parallel or orthogonal to the polarization direction such as the background, and it takes time to take an image. There was a point.
In addition, a mechanism for rotating at least the 90 ° polarizing filter 19 is required, and there is a problem that the rotating device 20 is complicated and the entire device becomes large.
[0008]
Further, in the case of an imaging device that uses a detection device that detects a polarization plane from the background and rotates the polarization filter 19 so as to be orthogonal to the polarization plane obtained from the detection device, the detection device is separately required. There was also the problem of becoming.
[0009]
An object of the present invention is to solve the above-described problems, and to obtain an imaging apparatus capable of performing imaging in a short time without substantially reducing the target detection performance. Objective.
[0010]
[Means for Solving the Problems]
  The imaging device of the present invention isEnterAn optical system including a polarizer that separates incident light rays into plane polarized light orthogonal to each other, an imaging lens that forms an image for each of the plane polarized light separated by the polarizer, and the optical system. The2 images correspond to each imageAn imaging device comprising: a detector for converting into an electric signal; and a signal processing device for processing the electric signal converted by the detectorBecauseThe polarizer is arranged such that the direction of the plane polarized light is parallel to the ground plane or orthogonal to the ground plane.the aboveThe inclination correction means for detecting the inclination with respect to the ground plane and correcting the inclination described above.the aboveCorrect so that the plane polarization is parallel to the ground plane or perpendicular to the ground planeAnd distinguishing the target from the background based on the difference between the electrical signals corresponding to each of the two images..
[0011]
  The imaging device of the present invention isAn imaging system comprising: an optical system including an imaging lens; a detector that converts an image formed by the optical system and a polarizer into an electrical signal; and a signal processing device that processes the electrical signal converted by the detector. The polarizer separates rays incident on the polarizer into plane-polarized light components orthogonal to each other so that the direction of the plane-polarized light is parallel to the ground plane or perpendicular to the ground plane. And two images corresponding to each of the separated plane polarized light components formed by the optical system and the polarizer, and the inclination with respect to the ground plane is detected by the inclination detecting means, and The plane polarization is corrected by an inclination correction means for correcting the inclination so that the plane polarized light is parallel to the plane or perpendicular to the plane, and the electric signals corresponding to the two images are connected to each other. To discriminate the target from the background based on the difference.
[0012]
  The imaging device of the present invention isA prism that divides incident light into two, a first polarizer that transmits one of the two light beams divided into plane polarized light, and transmits the other of the two light beams divided into the plane. 2 corresponding to each of the second and second light beams transmitted through the first polarizer and the second polarizer, respectively, which are polarized into plane polarized light orthogonal to the polarized light. An optical system including an imaging lens for forming one image, a detector for converting two images formed by the optical system into electrical signals corresponding to the respective images, and an electrical signal converted by the detector An image pickup apparatus including a signal processing device for processing, wherein the first polarizer unit and the second polarizer unit are configured such that the direction of the plane polarized light is parallel to the ground plane or orthogonal to the ground plane. Arranged to be The inclination detecting means detects the inclination with respect to the ground plane, and the inclination correcting means for correcting the inclination corrects the plane polarized light so that it is parallel to or perpendicular to the ground plane. And distinguishing the target from the background based on the difference between the electrical signals corresponding to each of the two images..
[0013]
  The imaging apparatus according to the present invention includes a mirror that divides an incident light beam into two, a first polarizer that transmits one of the two light beams divided to be polarized into plane polarized light, and the two light beams divided into two. A second polarizer that transmits the other and polarizes into plane-polarized light orthogonal to the plane-polarized light, and the one light beam and the other light that respectively transmit through the first polarizer and the second polarizer. An optical system including an imaging lens that forms two images corresponding to each of the light beams; a detector that converts the two images formed by the optical system into electrical signals corresponding to the respective images; and the detector And a signal processing device that processes the electrical signal converted by the first polarization unit and the second polarizer unit, wherein the plane polarization direction is parallel to the ground plane or One that is perpendicular to the ground plane The inclination detecting means detects the inclination with respect to the ground plane, and the inclination correcting means for correcting the inclination causes the plane polarized light to be parallel to the ground plane or perpendicular to the ground plane. And discriminate the target from the background based on the difference between the electrical signals corresponding to each of the two images..
[0014]
  The imaging device of the present invention is an optical system that forms an image from incident light rays, and is composed of a birefringent material having a different refractive index depending on the polarization direction, and the extraordinary optical axis of the birefringent material is parallel to the ground plane. Two images corresponding to an optical system including an imaging lens arranged in a vertical direction or perpendicular thereto and a polarized light component parallel to and perpendicular to the abnormal optical axis formed by the optical system, respectively. An imaging device comprising a detector for converting into an electrical signal and a signal processing device for processing the electrical signal obtained by the detector, the difference between the electrical signals corresponding to each of the two images Discriminate goals from background based on.
[0024]
An imaging apparatus according to the present invention includes an optical system including an imaging lens that is formed of a birefringent material that forms an image from light rays incident from an object and has a different refractive index depending on the polarization direction, and an image formed by the optical system. In the imaging device comprising a detector that converts the electrical signal into an electrical signal and a signal processing device that processes the electrical signal obtained by the detector, the imaging lens has a direction in which the abnormal optical axis is parallel to the ground plane or It is arranged in the direction perpendicular to it.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, each embodiment of the present invention will be described. In each embodiment, the same or equivalent members and parts will be described with the same reference numerals.
Embodiment 1 FIG.
1 is an optical path diagram of an image pickup apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is a polarizer that transmits a polarized light component parallel to the ground plane and reflects a polarized light component that is orthogonal to the polarized light component, and 2a is a transmitted light image that collects the electromagnetic wave transmitted through the polarizer 1 and forms an image. The lens 3a detects the image formed by the transmitted light imaging lens 2a and converts it into an electrical signal. The transmitted light detector 2b condenses the electromagnetic wave reflected by the polarizer 1 and forms a reflected light image. The image lens 3b detects the image formed by the reflected light imaging lens 2b and converts it into an electrical signal, and 4 represents the electrical signal obtained from the transmitted light detector 3a and the reflected light detector 3b. A signal processing device for processing.
[0044]
The polarizer 1 needs to reflect a polarization component orthogonal to the direction of the polarizer, but as a polarizer satisfying such conditions, a wire grating, a polarizing prism, an interference filter using a birefringent material, or the like There is.
[0045]
In the figure, the transmitted light imaging lens 2a and the reflected light imaging lens 2b are shown as a single lens. However, of course, a plurality of lenses may be used, and a function of imaging light rays in the same manner as a reflecting mirror or the like. Anything provided is sufficient. An arrow symbol indicates a polarization direction in which the vibration direction of the electromagnetic wave is parallel to the ground plane, and a symbol indicated by a cross in a circle indicates a polarization direction in which the vibration direction of the electromagnetic wave is orthogonal thereto.
[0046]
In the imaging apparatus having the above configuration, the polarizer 1 detects a polarized light component horizontal to the ground plane as an image by the transmitted light detector 3a and detects a polarized light component orthogonal to the polarized light component by the reflected light detector 3b. Is done.
Then, the signal processing device 4 performs signal processing to add the signal from the transmitted light detector 3a and the signal from the reflected light detector 3b, thereby obtaining the luminance information in the same manner as the imaging device in which no polarizer is used. Can be obtained.
Further, it is possible to know whether the light beam is polarized by taking the difference between the signals from the transmitted light detector 3a and the reflected light detector 3b. That is, when the light beam is not polarized, the value of the signal difference is zero.
[0047]
The transmitted light detector 3a and the reflected light detector 3b simultaneously detect plane polarized light orthogonal to and separated from each other by the polarizer 1, and can capture images in a short time. Further, there is no time lag between the images detected by the two detectors 3a and 3b, and there is no influence of temporal changes in the subject and the imaging environment.
[0048]
Here, with respect to the light from the subject, the polarized light intensity component is Ip, the unpolarized light intensity component is In, and the angle between the polarization plane of the polarization component and the polarization direction of the polarizer 1 is θ (0 ° ≦ θ <180 °). Here, the direction in which the electric field vector of the light beam transmitted through the polarizer 1 vibrates is called the polarization direction. At this time, the signal amount of the transmitted light detector 3a is Ia = A [In / 2 + Ip (cos θ).²The signal amount of the reflected light detector 3b is Ib = A [In / 2 + Ip (sin θ)²] (A is a constant). Therefore, the signal amount difference between the transmitted light detector 3a and the reflected light detector 3b is ΔI = Ia−Ib = A · Ip · Cos 2θ. That is, when θ = 0 ° and 90 °, ΔI is maximum and the S / N ratio is the highest, but when θ = 45 ° and 135 °, the light beam is unpolarized even if it is polarized. Therefore, in order to obtain polarization information with high accuracy, it is necessary to perform imaging under the conditions of θ≈0 ° and 90 °.
[0049]
By the way, the polarization plane in the polarization component of the light emitted from and reflected from the object generally appears parallel to the object surface during reflection and perpendicular to the radiation. Therefore, the polarization information can be obtained with high accuracy by making the polarization direction of the polarizer 1 parallel or perpendicular to the object plane as described above.
In general, artificial surfaces such as water surfaces and buildings / vehicles exhibiting high polarization characteristics have many planes and vertical wall surfaces substantially parallel to the ground plane. For this reason, polarization information can be obtained with high accuracy by arranging the polarization direction of the polarizer 1 parallel or perpendicular to the ground plane.
[0050]
In the above-described embodiment, the polarizer 1 in the direction that transmits the polarization component parallel to the ground plane is arranged. However, the same effect can be obtained by arranging the polarizer so as to transmit the polarization component perpendicular thereto. Of course.
[0051]
In the above-described embodiment, the signal amount difference ΔI between the transmitted light detector 3a and the reflected light detector 3b is used as a method for evaluating the polarization characteristics. This is used between the transmitted light detector 3a and the reflected light detector 3b. You may evaluate by the value normalized by dividing the signal amount difference ΔI by the sum of the signal amounts. That is, ε = (Ia−Ib) / (Ia + Ib) may be used as the evaluation value of the polarization characteristic. The magnitude of the signal amount difference ΔI is proportional to the polarized light intensity component Ip and varies depending on the luminance. However, since the magnitude of ε is always normalized to −1 ≦ ε ≦ 1, the magnitude of the luminance is large. Evaluation that is not affected by
It is also effective to evaluate the signal amount by the transmitted light detector 3a and the reflected light detector 3b using a two-dimensional graph as shown in FIG. Since the luminance characteristic and the polarization characteristic can be simultaneously evaluated on the two-dimensional graph, discrimination / classification using the two characteristics can be easily performed.
[0052]
Embodiment 2. FIG.
3 is an optical path diagram showing an imaging apparatus according to Embodiment 2 of the present invention.
In this embodiment, an optical system including an imaging lens 2 d that forms an image with respect to light rays incident from an object is provided on the incident side of the polarizer 1. Other components are the same as those in the first embodiment.
In the imaging apparatus of the second embodiment, the polarizer 1 is arranged on the exit side of the imaging lens 2d, so that the imaging lens 2d shares the transmitted light and the reflected light of the polarizer 1. The number of parts can be reduced. Further, since the electromagnetic waves collected by the imaging lens 2d are incident on the polarizer 1, the polarizer 1 is miniaturized, and the imaging device is miniaturized in combination with the reduction in the number of parts.
[0053]
By the way, in Embodiment 2 described above, for example, when a flat plate is used for the polarizer 1, unlike in Embodiment 1 in which parallel rays pass through the polarizer 1, the optical path length of the rays passing through the polarizer 1 depends on the region. Differently, aberrations occur in the images formed on the detectors 3a and 3b. For this reason, as shown in FIG. 4, by using the wedge-shaped polarizer 51, the aberration of the image formed on the detectors 3a and 3b can be reduced. Note that the image plane formed by the transmitted light detector 3a may be inclined due to the influence of the wedge-shaped polarizer 51. However, the reflected light detector 3a is inclined to reduce the difference in optical path length. By doing so, the inclination of the image plane is reduced.
[0054]
In addition, aberrations can be suppressed by making the surfaces of the polarizer 1 perpendicular to each other when the principal ray enters the polarizer 1 and exits from the polarizer 1.
FIG. 5 shows an example of the polarizer 1 in which the aberration is reduced in this way. This polarizer 1 is a rectangular parallelepiped having a polarizer plane 21 inside, and the polarizer plane 21 is perpendicular to two opposed planes of the rectangular parallelepiped, and the angle formed with respect to the other four planes is 45. Degree. The polarizer surface 21 has a function of separating incident light beams into plane polarized light that is orthogonal to each other and transmitted through one side and plane polarized light that the other reflects. At this time, when the principal ray enters the polarizer 1 and exits from the polarizer 1, each surface is always vertical, which is equivalent to entering the parallel plate, and almost no aberration occurs in the detectors 3a and 3b.
Even in the above configuration, higher-order aberrations occur, but the influence can be reduced by making the surface of the polarizer aspherical.
[0055]
In the second embodiment, the polarizer 1 is placed behind the imaging lens 2d. However, similarly to the case where the polarizer 1 is provided inside the optical system 2 as shown in FIG. The effect of miniaturization can be obtained.
At this time, by arranging the polarizer 1 in a region where the peripheral ray is nearly parallel to the principal ray, the aberration generated by the insertion of the polarizer 1 can be reduced.
In particular, when the imaging lens 2d in front of the polarizer 1 is an afocal lens, the light beam transmitted through and reflected by the polarizer 1 is a parallel light beam, and the light beam is thinner than the light beam incident on the imaging lens 2d. Become. As a result, no aberration occurs and the polarizer 1 can be miniaturized.
[0056]
Embodiment 3 FIG.
FIG. 7 is an optical path diagram of the image pickup apparatus according to Embodiment 3 of the present invention. Reference numeral 6 denotes a front lens provided with a field stop 7, and reference numeral 8 denotes a prism, which separates the light beam into two at the position of the pupil. 1a is a 1st polarizer part, 1b is a 2nd polarizer part, the 1st polarizer part 1a permeate | transmits only the polarization component parallel to a ground plane among the incident light rays, and the 2nd polarizer part 1b and it Unlike the first and second embodiments, each of them transmits only orthogonal polarization components and does not need a function of reflecting incident components. That is, the combination of the first polarizer portion 1a and the second polarizer portion 1b corresponds to the polarizer 1 of the first and second embodiments.
[0057]
In the imaging apparatus according to the third embodiment, incident light from a subject forms an image once at the position of the field stop 7 in the front lens 6. After that, when the front lens 6 exits, the parallel light is returned again and enters the prism 8. The light beam is divided into two by the prism 8, and only the component parallel to the ground plane and the component orthogonal thereto are taken out by the first polarizer portion 1a and the second polarizer portion 1b, respectively. Then, the two divided light beams pass through the transmitted light imaging lens 2a to form images in different areas on the same transmitted light detector 3a, and the transmitted light detector 3a simultaneously converts the two images into electrical signals. Is done. The luminance information and the polarization information are obtained from the electrical signals of the polarization component parallel to the obtained ground plane and the polarization component orthogonal to the polarization component, as in the first embodiment.
[0058]
In the third embodiment, the transmitted light detector 3a is shared by two light beams of a polarized light component parallel to the ground plane and a polarized light component orthogonal thereto, so that the number of parts can be reduced and the imaging apparatus can be downsized. it can.
[0059]
In the third embodiment, the light beam is divided into two parts by using the prism 8, but the same can be achieved by using a mirror. The prism must be a material that can transmit electromagnetic waves, and the material is limited. On the other hand, if the mirror can be coated with a reflective film, the optical characteristics of the base material are not limited.
In the above embodiment, the prism, mirror, and polarizer are separate parts, but they may be integrated. For example, the prism 8 in FIG. 7 can be integrated by providing a polarization function on the surface facing the polarizer portions 1a and 1b. By integrating the prism and the polarizer, the number of parts is reduced, and the imaging device is downsized.
[0060]
Embodiment 4 FIG.
FIG. 8 is an optical path diagram of an imaging apparatus according to Embodiment 4 of the present invention. Reference numeral 9 denotes a mirror provided behind the polarizer 1, and the orientation of the polarizer 1 is naturally arranged in a direction parallel to or perpendicular to the ground plane.
In the imaging apparatus of the fourth embodiment, the polarized light component parallel to the ground plane of the incident light beam is transmitted through the polarizer 1, and the light beam orthogonal thereto is reflected to form an image on the detector 3 by the imaging lens 2e. . The transmitted light is reflected by the mirror 9 and again passes through the polarizer 1 and then enters the imaging lens 2e. At this time, the incident light enters the imaging lens 2e at an angle different from the reflected light depending on the angle provided on the mirror 9. . Therefore, since an image is formed on the detector 3 at a position different from the reflected light, two images can be detected by one detector 3 as in the third embodiment.
[0061]
In the imaging apparatus of the third embodiment, the light beam of the pupil is divided and then polarized, and thus half of the light beam is lost. On the other hand, in the fourth embodiment, the light beam is divided into two by polarization. There is no loss and a signal amount twice that of the third embodiment can be obtained.
In this embodiment, the configuration in which the transmitted light is reflected by the mirror 9 is shown, but the configuration may be such that the reflected light is reflected by the mirror and the light beam is guided to the imaging lens.
[0062]
Embodiment 5 FIG.
FIG. 9 is an optical path diagram of the image pickup apparatus according to Embodiment 5 of the present invention. A birefringent member 10 is provided between the front lens 6 and the imaging lens 2d and has a function as a prism having a different refractive index depending on the polarization direction. The birefringent member 10 may be a natural uniaxial crystal or biaxial crystal, or may be a photonic crystal artificially created by laminating a fine structure.
[0063]
In the imaging apparatus according to the fifth embodiment, the birefringent member 10 is arranged to be a prism that exhibits different refractive indexes for a polarized light component parallel to the ground plane and a polarized light component perpendicular thereto with respect to the incident light beam. Therefore, the incident light beam is divided into two polarization components by the birefringent member 10, and the same effect as in the third embodiment can be obtained.
At this time, in Embodiment 3 above, the light beam of the pupil is divided and then polarized, so that half of the light beam is lost. In contrast, in Embodiment 5, the light beam is divided into two by polarization. There is no loss and a signal amount twice that of the third embodiment can be obtained.
[0064]
Embodiment 6 FIG.
FIG. 10 is an optical path diagram of the image pickup apparatus according to Embodiment 6 of the present invention. This imaging apparatus is formed by an optical system including a birefringent imaging lens 2c formed of a birefringent material that forms an image from light rays incident from an object and has a refractive index that varies depending on the polarization direction, and the optical system. A detector 3 for converting an image into an electric signal and a signal processing device 4 for processing the electric signal obtained by the detector 3 are provided.
As the birefringent lens 2c, a naturally existing uniaxial crystal or biaxial crystal can be used, or a photonic crystal artificially formed by laminating a fine structure may be used.
[0065]
In the imaging apparatus of Embodiment 6, the birefringent imaging lens 2c is arranged so as to be a lens that exhibits different refractive indexes for a polarized light component parallel to the ground plane and a polarized light component perpendicular thereto with respect to the incident light beam. For this reason, the incident light rays have different focal lengths between the two polarization components, and the surface on which the image is formed also moves back and forth on the optical axis.
Therefore, for example, when an image is detected while moving the detector 3 back and forth, the image intensities for the two polarization directions are obtained as electrical signals in order in time (FIG. 11). The maximum value and the minimum value of the electric signal are image intensities corresponding to two polarization directions.
[0066]
Therefore, it is possible to obtain luminance and polarization information by directly analyzing the electric signal to obtain the maximum value and the minimum value and performing signal processing in the same manner as in the first embodiment. The polarization characteristic (Ia-Ib) can be obtained by electrically obtaining the fluctuation component (AC component). Further, luminance information (Ia + Ib) can be obtained by calculating an integral or an average to obtain a non-variable component (DC component).
Further, the movement of the detector 3 used here can use the mechanism normally used for focusing the lens as it is, and does not require a new mechanism.
[0067]
Embodiment 7 FIG.
FIG. 12 is an optical path diagram of the image pickup apparatus according to Embodiment 7 of the present invention. Reference numeral 11 denotes a gyro sensor that is an inclination detection unit that is attached to the imaging device and can determine an inclination with respect to the ground plane. Reference numeral 12 denotes an attitude control unit that is connected to the gyro sensor 11 and corrects the inclination of the imaging device. Based on the tilt information with respect to the ground plane obtained by the sensor 11, the orientation of the imaging device is adjusted so that the polarization direction of the polarizer 1 is parallel to or perpendicular to the ground plane.
[0068]
As described in the first embodiment, if the polarization direction of the polarizer 1 is not parallel to or perpendicular to the horizontal plane, the S / N ratio with respect to the acquisition data of the polarization characteristics is lowered. Therefore, in the seventh embodiment, the gyro sensor 11 and the attitude control device 12 are used to adjust the polarization direction of the polarizer 1 so that it is always parallel to or perpendicular to the ground plane. The data can be acquired with the / N ratio. Since the polarization direction of the polarizer 1 is only required to be parallel to or perpendicular to the ground plane, the adjustment angle range of the attitude control device 12 may be 45 ° or less.
[0069]
In the above embodiment, the gyro sensor is used to determine the tilt of the imaging apparatus. However, the tilt may be determined by knowing the vertical direction using, for example, a gravity sensor (acceleration sensor) that is a tilt detection means. In addition, the inclination can also be obtained by using the horizon of the horizontal plane of the image by the imaging device, the horizontal line of the horizontal plane, or the like.
In the embodiment described above, the polarization direction of the polarizer 1 is adjusted to be parallel to the ground plane by controlling the attitude of the entire imaging apparatus using the attitude control device. However, the polarizer 1, the transmitted light imaging lens 2a, and the transmitted light are adjusted. The same effect can be obtained simply by adjusting the angle with respect to the detector 3a. Alternatively, the angle of the polarizer 1 may be adjusted by using a rotation mechanism that is a tilt correction unit that rotates only the polarizer 1.
[0070]
Embodiment 8 FIG.
FIG. 13 is an optical path diagram of the imaging apparatus according to the eighth embodiment of the present invention. Reference numeral 18 denotes an image rotation device as tilt correction means, which has a function of rotating an image picked up by the image pickup device at an arbitrary angle. In general, the image rotation device 18 is constituted by a prism.
In the eighth embodiment, based on the tilt information of the imaging device with respect to the ground plane obtained by the gyro sensor 11 as the tilt detecting means, the polarization direction of the light beam by the polarizer 1 is always the same as the ground plane using the image rotation device 18. Image is taken with the angle corrected to be parallel. As a result, data acquisition can always be performed with a high S / N ratio, as in the seventh embodiment. Note that the means for obtaining the angle of the ground plane may be other than the gyro sensor 11, as in the seventh embodiment.
The image rotation device 18 may have a scanner function for changing the direction of incident light and arbitrarily selecting a region to be imaged.
[0071]
Embodiment 9 FIG.
  FIG. 14 is an optical path diagram of an image pickup apparatus according to Embodiment 9 of the present invention. In this embodiment, light rays from the subject are incident on the polarizer 1.In the direction opposite to the direction of reflectionA non-radiating non-radiating body 13 is arranged. The electromagnetic waves radiated and reflected from the non-radiating body 13 are negligibly small.
[0072]
The polarizer 1 has a function of transmitting and reflecting light rays from the subject and guiding the light rays to the transmitted light imaging lens 2a and the reflected light imaging lens 2b according to the polarization direction. Similarly, light incident from the back side of the incident polarizer 1 is transmitted and reflected by the polarizer 1. A light beam incident on the polarizer 1 from the back side of the polarizer 1 transmits a polarization component parallel to the ground plane, enters the reflected light imaging lens 2b as stray light, and is similar to the signal from the subject by the reflected light detector 3b. It becomes noise because it is detected.
On the other hand, since the polarization component orthogonal to the light is reflected by the polarizer 1, it enters the transmitted light imaging lens 2a as stray light and is added as noise of the signal from the transmitted light detector 3a. As a result, the noise of the imaging device increases, and the performance of the device decreases. In particular, when infrared rays are used as electromagnetic waves, radiation is easily generated by heat, so the influence cannot be ignored.
[0073]
In the eighth embodiment, the influence of stray light is eliminated by arranging the non-radiating body 13 that can ignore the emission and reflection of electromagnetic waves as a noise source.
In the above embodiment, the non-radiating body 13 is so small that reflection and radiation can be ignored. However, only the signal amount difference ΔI between the transmitted light detector 3a and the reflected light detector 3b, which shows polarization characteristics, is important. In some cases, the non-radiating body 13 may have reflection and radiation as long as it does not have polarization characteristics. This is because, when the stray light has no polarization characteristic, the magnitudes of the stray light appearing in the two polarization directions are equal and are canceled when calculating ΔI.
[0074]
In addition, when the luminance information is used only for viewing only the fluctuation from the average value, for example, when there is no problem with the offset, if the spatial distribution of the non-radiating body 13 does not change, there is no reflection or radiation. May be. Alternatively, if the radiation and reflection amount of the non-radiating body is always substantially constant, for example, the amount can be measured in advance, and the effect can be removed by correcting the amount during imaging.
[0075]
Embodiment 10 FIG.
FIG. 15 is an optical path diagram of the image pickup apparatus according to Embodiment 10 of the present invention. The transmitted light imaging lens 2a has a longer focal length than the reflected light imaging lens 2b.
In Embodiment 10, since the focal lengths of the transmitted light imaging lens 2a and the reflected light imaging lens 2b are different, the sizes of the formed images are also different. As a result, the transmitted light detector 3a detects an image with a high resolution but a narrow viewing angle, and the reflected light detector 3b detects an image with a low resolution but a wide viewing angle. For this reason, in the signal processing device 4, for example, near the center of the subject, the resolution is increased using the image of the transmitted light detector 3a, and the viewing angle is widened using the image of the reflected light detector 3b in the peripheral portion. It becomes possible. From the image obtained by this processing, it is naturally not possible to obtain information such as a polarization component parallel to the ground plane for the image of the region outside the transmitted light detector 3a, but it is effective for performing edge detection from the image, for example. It is.
[0076]
In the above embodiment, the transmitted light imaging lens 2a has a longer focal length than the reflected light imaging lens 2b. However, the same effect can be obtained even if the transmitted light imaging lens 2a is shorter. Even if the transmitted light imaging lens and the reflected light imaging lens have the same size, the same effect can be obtained if the transmitted light detector 3a and the reflected light detector 3b have different resolutions. Alternatively, by enlarging only one of the detectors, an image with a wide viewing angle can be obtained at a lower cost than when the two detectors are enlarged.
[0077]
In the above embodiment, the resolution of the image is increased by increasing the focal length of the transmitted light imaging lens 2a. However, the transmitted light detector is moved in parallel with the image plane, and the interval is equal to or smaller than the resolution of the detector. It is also possible to increase the resolution of the image by sampling the image intensity. For example, an image having a resolution twice that of the detector can be obtained by slightly vibrating the detector with a size half that of the detector and sampling the image intensity at the interval. Even if only one of the detectors is moved, the same effect as that of the above-described embodiment can be obtained. However, by moving the two detectors, an image having no luminance and polarization information missing in all regions and resolutions can be obtained.
Alternatively, it is possible to increase the resolution of the image by shifting the position of the detector by a size less than the resolution. For example, it is possible to obtain an image having a resolution twice that of the detector resolution by disposing one detector with a half of the resolution of the detector with respect to the other.
[0078]
Embodiment 11 FIG.
FIG. 16 is an optical path diagram of the image pickup apparatus according to Embodiment 11 of the present invention. Reference numeral 14a denotes a transmitted light wavelength filter for limiting the wavelength band of the light beam incident on the transmitted light detector 3a, and reference numeral 14b denotes a reflected light wavelength filter for limiting the wavelength band of the light beam incident on the reflected light detector 3b.
In the eleventh embodiment, the wavelength filters 14a and 14b are provided in front of the detectors 3a and 3b to limit the wavelength band, thereby enabling image analysis in the wavelength region in addition to the luminance characteristics and the polarization characteristics.
For example, when detecting a target with characteristic luminance and polarization characteristics for a specific wavelength band, it is easy to detect the target by acquiring an image using a wavelength filter that restricts the light beam to that wavelength band. Can be.
[0079]
In the above embodiment, the wavelength filters 14a and 14b are provided in front of the detectors 3a and 3b. However, the wavelength filters 14a and 14b may be provided in another place in the optical path, for example, before or after the polarizer.
Further, although the wavelength filters 14a and 14b are provided for two polarized light beams, a wavelength filter may be inserted only for one polarized light beam.
Further, by providing a means for attaching / detaching or exchanging the wavelength filter, the wavelength can be dynamically selected, and image analysis in an advanced wavelength region becomes possible.
[0080]
In addition, for example, an acousto-optic device in which the transmission wavelength can be changed by changing the periodic interval of the refractive index distribution of the wavelength filter, or the transmission wavelength can be changed by changing the interference condition by changing the reflection plate interval by electrostatic attraction. It is also possible to dynamically change the selected wavelength by using a tunable filter such as a micromachining device that can be used.
[0081]
In the above embodiment, the wavelength filters 14a and 14b are single elements having only a wavelength limiting function, but the same effect can be obtained by providing the wavelength selecting function to other components. For example, the transmitted light imaging lens 2a and the reflected light imaging lens 2b may be provided with a wavelength selection function, or the polarizer 1 may be integrated with the wavelength filter. As a result, the number of parts can be reduced, and the imaging apparatus can be reduced in size.
[0082]
Embodiment 12 FIG.
FIG. 17 is an optical path diagram of the image pickup apparatus according to Embodiment 12 of the present invention. Reference numeral 15 denotes a micro-rotation device having a function of rotating the polarizer 1 by a minute angle. The signal processing device 4 obtains a value that is separated and maximizes the signal amount difference of the light beam by the rotation of the polarizer 1 by a minute angle. It is like that.
In the imaging device according to the twelfth embodiment, the measurement accuracy of the polarization characteristics can be improved by rotating the polarizer 1 by a small angle. For example, the signal amount difference ΔI = A · Ip · Cos 2θ between the transmitted light detector 3a and the reflected light detector 3b shown in the first embodiment is used as the evaluation value of the polarization characteristic. θ is an angle formed by the polarization plane of the incident light and the polarization direction of the polarizer 1, and ΔI increases as θ decreases, so that the S / N ratio of the measurement improves. As described above, by arranging the polarizer 1 in parallel with the ground plane, it is possible to capture an image with sufficiently high measurement accuracy. However, the polarizer 1 is rotated by a small angle and imaged at a point where ΔI is maximized. As a result, a slight remaining error can be removed. Further, the plane of polarization of the light beam can be obtained by obtaining θ at the point where ΔI is maximum, and can be used as an evaluation value for discriminating the target. As described above, the plane of polarization of radiation emitted from and reflected from an object generally appears parallel to the object surface when reflected and perpendicular to when emitted. Therefore, the inclination of the object surface can be known by using the polarization plane of the light beam.
[0083]
In the above embodiment, the maximum value is used for the signal amount difference ΔI between the detector 3a and the detector 3b taken as an example, but ΔI is a function of cos 2θ as described above. For this reason, the signal processing device 4 rotates the polarizer 1 by a minute angle and uses the rotation angle θ and constants C and θo as the signal amount difference ΔI of the separated light rays, ΔI = C · cos 2 (θ−θo). And the constants C and θo are calculated, and the coefficient C may be used as an evaluation value representing the polarization characteristics (FIG. 18). Note that θo represents the polarization plane as in the above embodiment. At this time, noise generated during measurement is suppressed by fitting, so that measurement accuracy can be improved. Even if the maximum value of ΔI is not included in the measurement point, the value can be complemented by fitting, so that the maximum value of ΔI and θo can always be obtained.
[0084]
In order to reduce the load of calculation performed at the time of analysis, the signal processing device 4 rotates the polarizer 1 by a slight angle, and uses the rotation angle θ and the constants C and θo to determine the signal amount difference ΔI of the separated rays. ΔI = C [1-4 (θ−θo)²] To calculate the constants C and θo. Since θ and θo are sufficiently small, ΔI is set to C [1-4 (θ−θo).²], The error generated by this approximation is small.
[0085]
Embodiment 13 FIG.
FIG. 19 is an optical path diagram of an image pickup apparatus according to Embodiment 13 of the present invention. Reference numeral 16 denotes a four-divided prism that separates the light beam into four at the position of the pupil. The four divided prisms 16 are provided with polarizer portions 1a, 1b,... In FIG. 19, the other two polarizer portions are arranged on the front side and the back side of the paper, respectively. They are arranged in polarization directions that form angles of 0 ° (parallel), 45 °, 90 °, and 135 ° with the ground plane.
In the thirteenth embodiment, the light beam is divided into four to enable measurement at angles of 45 ° and 135 ° in addition to the directions of polarization parallel to and perpendicular to the horizontal plane. As a result, the light intensity at four points is obtained as shown in FIG. The change in intensity with respect to the angle θ of the polarizer is I = In + Ip [cos (θ−θo).²Therefore, the magnitude of the polarization component and the plane of polarization can be determined by fitting the measurement result to obtain Ip and θo.
[0086]
In the above embodiment, the luminous flux is divided into four, but the size of the polarization component and the plane of polarization can be obtained by the same method with three or more divisions. In addition, although the prism is used for splitting the light beam, it may be split using a mirror as in the third embodiment.
[0087]
Embodiment 14 FIG.
FIG. 21 is an optical path diagram of the image pickup apparatus according to Embodiment 14 of the present invention. Reference numeral 1e denotes a liquid crystal polarizer that can have an arbitrary polarization direction by applying a voltage, and reference numeral 17 denotes a polarizer control device that controls the polarization direction of the liquid crystal polarizer 1e.
In the fourteenth embodiment, a liquid crystal polarizer 1e is used as a polarizer, and imaging is performed with respect to a polarization direction parallel to the ground plane and a polarization direction perpendicular thereto. Since the liquid crystal polarizer 1e can electrically create a polarization direction of an arbitrary angle at high speed, unlike the conventional mechanical rotation, the length of the scanning time is not a problem. Also, since this embodiment requires intermittent state changes of two polarization directions, it is clear that the efficiency is higher than that of continuous scanning of mechanical rotation.
[0088]
In the above embodiment, the polarization direction is set to two directions, ie, a direction parallel to the ground plane and a direction perpendicular thereto. By increasing the polarization direction, the measurement accuracy can be improved and polarization can be improved in the same manner as in Embodiments 11 and 12. You can ask for the surface.
In the above, liquid crystal is used as a polarizer that can create a polarization direction of any direction. However, for example, an acoustooptic device capable of performing plane polarization by the effect of diffraction generated from a periodic structure of a refractive index distribution, stress, electric field, etc. The same effect can be obtained even when an interference filter using a material in which birefringence occurs due to application of a magnetic field (photoelastic effect, Kerr effect, magnetic birefringence) as a polarizer.
[0089]
【The invention's effect】
As described above, according to the imaging apparatus of the present invention, an image is obtained for each of the polarizer that separates the light rays incident from the object into the mutually orthogonal plane polarized light and the plane polarized light separated by the polarizer. An imaging apparatus comprising: an optical system including an imaging lens to be formed; a detector that converts an image formed by the optical system into an electrical signal; and a signal processing device that processes the electrical signal converted by the detector The polarizer is arranged so that the direction of the plane polarized light is parallel to the ground plane or orthogonal to the ground plane, so that polarization information can be obtained with high accuracy and in a short time. Can be used for imaging.
[0090]
Further, according to the imaging apparatus of the present invention, an optical system including an imaging lens that forms an image with respect to a light ray incident from an object, and polarized light that separates an image formed by the optical system into plane polarized light orthogonal to each other In the imaging device comprising: a detector; a detector that converts the two images separated by the polarizer into an electrical signal; and a signal processing device that processes the electrical signal converted by the detector. The children are arranged such that the direction of the plane polarized light is parallel to the ground plane or orthogonal to the ground plane, so that polarization information can be obtained with high accuracy and imaging is performed in a short time. be able to.
[0091]
Further, according to the imaging apparatus of the present invention, an optical system including an imaging lens that forms an image with respect to a light beam incident from an object, a detector that converts an image formed by the optical system into an electrical signal, In the imaging apparatus including the signal processing device that processes the electrical signal converted by the detector, a polarizer that is provided inside the optical system and separates the light rays into plane polarized light that is orthogonal to each other is the plane polarized light. Since the direction is arranged so as to be parallel to the ground plane or orthogonal to the ground plane, polarization information can be obtained with high accuracy and imaging can be performed in a short time.
[0092]
Further, according to the imaging apparatus of the present invention, the optical system has the afocal lens provided in front of the polarizer on which the light beam is incident, so that the parallel light beam is incident on the polarizer and the detector has an aberration. An image with no image is formed.
[0093]
Further, according to the imaging apparatus of the present invention, the polarizer is separated into plane polarized light that transmits incident light and reflected plane polarized light, so that signals obtained by these plane polarized lights are used. In a short time, luminance characteristics and polarization characteristics can be evaluated simultaneously.
[0094]
Further, according to the imaging device of the present invention, since the cross-sectional shape of the polarizer is wedge-shaped, the difference in the optical path length of the light beam passing through the polarizer can be reduced, and the aberration of the image on the detector Can be reduced.
[0095]
Further, according to the imaging apparatus of the present invention, the polarizer has a plane of incidence of the principal ray on the polarizer and an exit plane from the polarizer perpendicular to the principal ray. Almost no aberration occurs.
[0096]
According to the imaging apparatus of the present invention, the prism for splitting the light beam into two is provided at the position of the pupil of the optical system, and the polarizer includes the first polarizer portion that is polarized into plane polarized light, and the plane. A second polarizer part that is polarized into plane polarized light orthogonal to the polarization, and the light beams divided into two by the prism are orthogonal to each other in the first polarizer part and the second polarizer part. Therefore, the luminance characteristics and polarization characteristics can be simultaneously evaluated in a short time by using signals obtained by these plane polarizations. In addition, the detector can share an image by two plane-polarized lights, reduce the number of parts, and reduce the size of the imaging device.
[0097]
According to the imaging apparatus of the present invention, the mirror that splits the light beam into two is provided at the position of the pupil of the optical system, and the polarizer includes the first polarizer section that is polarized into plane polarized light, and the plane polarized light. A second polarizer part that is polarized into plane-polarized light orthogonal to each other, and the light beams divided into two by the mirror are planar in directions orthogonal to each other by the first polarizer part and the second polarizer part. Since the light is polarized, the luminance characteristic and the polarization characteristic can be simultaneously evaluated in a short time by using the signals obtained by the plane polarized light. In addition, the detector can share an image by two plane-polarized lights, reduce the number of parts, and reduce the size of the imaging device.
[0098]
Further, according to the imaging device of the present invention, the polarizer is a prism having a refractive index that differs depending on the polarization direction, and therefore, the luminance characteristic and the polarization characteristic can be simultaneously evaluated. In addition, the detector can share an image by two plane-polarized lights, reduce the number of parts, and reduce the size of the imaging device. In addition, there is no loss of light due to polarization, and a large signal amount can be obtained.
[0099]
Further, according to the imaging device of the present invention, each optical system that forms an image of the light beam separated by the polarizer has a different focal length, so that, for example, the resolution is high near the center and the viewing angle is wide in the peripheral portion. It becomes possible to do.
[0100]
Further, according to the imaging apparatus of the present invention, the detector is movable along the optical axis by the moving means, and detects the image while moving. The detector can be positioned at the focal length.
[0101]
In addition, according to the imaging apparatus of the present invention, the detectors are shifted and arranged with a size less than or equal to the resolution of the detector, so that it is possible to increase the resolution of the image.
[0102]
Further, according to the imaging apparatus of the present invention, plane polarized light in different directions is converted into an electric signal by the same detector, so that the number of parts can be reduced and the imaging apparatus can be downsized. .
[0103]
In addition, according to the imaging apparatus of the present invention, an optical system including an imaging lens formed of a birefringent material that forms an image from a light ray incident from an object and has a different refractive index depending on the polarization direction, and the above optical system In the imaging device including a detector that converts the formed image into an electrical signal and a signal processing device that processes the electrical signal obtained by the detector, the imaging lens has an abnormal optical axis on the ground plane. Since they are arranged in a parallel direction or a direction perpendicular thereto, the incident light beams have different focal lengths for the two polarization components, and the luminance characteristics and polarization can be evaluated by detecting the image by moving the detector.
[0104]
Further, according to the imaging apparatus of the present invention, a polarizer that plane-polarizes light incident from an object, an optical system that forms an image of the light transmitted through the polarizer and includes an imaging lens, and the optical system An image pickup apparatus comprising: a detector that converts the converted image into an electrical signal; and a signal processing device that processes the electrical signal converted by the detector, wherein the polarizer has at least a horizontal plane direction of the plane polarized light. The polarization information can be obtained with high accuracy.
[0105]
Further, according to the imaging apparatus of the present invention, since the polarizer is a liquid crystal element, it is possible to produce a polarization direction of an arbitrary angle electrically at high speed.
[0106]
Further, according to the imaging apparatus of the present invention, the inclination with respect to the ground plane is detected by the inclination detecting means, and the plane polarized light is parallel to or perpendicular to the ground plane by the inclination correcting means for correcting the inclination. Therefore, data can be acquired with a high S / N ratio.
[0107]
Further, according to the imaging apparatus of the present invention, since the inclination detecting means detects the inclination with respect to the ground plane from the photographed image, data can be acquired with a high S / N ratio.
[0108]
In addition, according to the imaging apparatus of the present invention, since a horizon or a horizontal line is detected from a captured image, data can be acquired with a high S / N ratio.
[0109]
Further, according to the imaging apparatus of the present invention, since the tilt correcting means is a rotating mechanism that rotates the polarizer, data can be acquired with a simple configuration and a high S / N ratio.
[0110]
Further, according to the imaging apparatus of the present invention, since the tilt correction means is an image rotating apparatus that rotates the imaging before the incident light to the polarizer, data can be acquired with a simple configuration and a high S / N ratio. It becomes.
[0111]
Further, according to the imaging apparatus of the present invention, the multi-divided prism that divides the light beam into at least three parts is provided at the position of the pupil of the optical system, and the polarizer is polarized at least into plane polarized light parallel to the ground plane. A first polarizer part, a second polarizer part polarized in a direction orthogonal to the plane polarized light, and a third polarizer part polarized in a direction other than parallel and perpendicular, and divided by the prism. Since each of the light beams is plane-polarized by the first polarizer part or the third polarizer part, it is possible to measure an angle other than an angle parallel to and perpendicular to the ground plane. .
[0112]
According to the imaging apparatus of the present invention, since the polarizer is provided with a micro-rotation device that rotates the polarizer within a minute angle range, the measurement accuracy of the polarization characteristics is improved.
[0113]
Further, according to the imaging device of the present invention, the signal processing device obtains a value that is separated and maximizes the signal amount difference of the light beam by the rotation of the minute angle of the polarizer. Can measure polarization characteristics
.
[0114]
Further, according to the imaging apparatus of the present invention, the signal processing apparatus rotates the polarizer by a minute angle, and uses the rotation angle θ and the constants C and θo to determine the signal amount difference ΔI of the separated light as ΔI = C · Since the process of fitting with cos2 (θ−θo) and calculating the constants C and θo is provided, noise generated during measurement is suppressed by the fitting, so that the measurement accuracy can be improved.
[0115]
Further, according to the imaging apparatus of the present invention, the signal processing apparatus rotates the polarizer by a minute angle, and uses the rotation angle θ and the constants C and θo to calculate the signal amount difference ΔI of the separated light as ΔI = C [ 1-4 (θ-θo)²] And noise generated during measurement is suppressed by fitting, so that measurement accuracy can be improved.
[0116]
Further, according to the imaging apparatus of the present invention, since the wavelength filter is provided in the optical path, the wavelength band of the light ray incident on the detector is limited, and image analysis in the wavelength region is possible.
[0117]
Further, according to the imaging device of the present invention, the wavelength filter can change the transmission band, so that the selected wavelength can be dynamically changed.
[0118]
In addition, according to the imaging apparatus of the present invention, the non-radiating non-radiating material is arranged on the other surface side of the polarizer where the light beam from the object is incident on the polarizer. Can be reduced.
[0119]
Further, according to the imaging device of the present invention, since the non-polarizing member having no polarization characteristic is arranged on the other side of the polarizer where the light beam from the object enters the polarizer, the stray light Can be reduced.
[0120]
Further, according to the imaging apparatus of the present invention, the uniform polarizer having uniform polarization characteristics is arranged in the entire region on the other surface side of the polarizer where the light beam from the object is incident on the polarizer. Therefore, the influence of stray light can be reduced.
[0121]
Further, according to the imaging apparatus of the present invention, the invariant polarizer that hardly changes the polarization characteristic with time is disposed on the other side of the polarizer where the light beam from the object is incident on the polarizer. Therefore, the influence of stray light can be reduced.
[Brief description of the drawings]
FIG. 1 is an optical path diagram of an imaging apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing signal amounts of the transmitted light detector and the reflected light detector of FIG. 1;
FIG. 3 is an optical path diagram of an imaging apparatus according to Embodiment 2 of the present invention.
FIG. 4 is an optical path diagram showing another example of an imaging apparatus according to Embodiment 2 of the present invention.
FIG. 5 is an optical path diagram showing another example of an imaging apparatus according to Embodiment 2 of the present invention.
FIG. 6 is an optical path diagram showing another example of the imaging apparatus according to Embodiment 2 of the present invention.
FIG. 7 is an optical path diagram of an imaging apparatus according to Embodiment 3 of the present invention.
FIG. 8 is an optical path diagram of an imaging apparatus according to Embodiment 4 of the present invention.
FIG. 9 is an optical path diagram of an imaging apparatus according to Embodiment 5 of the present invention.
FIG. 10 is an optical path diagram of an imaging apparatus according to Embodiment 6 of the present invention.
FIG. 11 is a relationship diagram between time and image intensity of the imaging apparatus of FIG.
FIG. 12 is an optical path diagram of an imaging apparatus according to Embodiment 7 of the present invention.
FIG. 13 is an optical path diagram of an imaging apparatus according to Embodiment 8 of the present invention.
FIG. 14 is an optical path diagram of an imaging apparatus according to Embodiment 9 of the present invention.
FIG. 15 is an optical path diagram of an imaging apparatus according to Embodiment 10 of the present invention.
FIG. 16 is an optical path diagram of an imaging apparatus according to Embodiment 11 of the present invention.
FIG. 17 is an optical path diagram of an imaging apparatus according to Embodiment 12 of the present invention.
18 is a diagram showing the relationship between the angle of the polarizer and the signal amount difference ΔI in the imaging apparatus shown in FIG.
FIG. 19 is an optical path diagram of an imaging apparatus according to Embodiment 13 of the present invention.
20 is a diagram showing the relationship between the angle of the polarizer and the light intensity in the imaging apparatus shown in FIG.
FIG. 21 is an optical path diagram of an imaging apparatus according to Embodiment 14 of the present invention.
FIG. 22 is an optical path diagram of a conventional imaging device.
23 is a relationship diagram between time and light intensity of the imaging apparatus in FIG. 22;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Polarizer, 1a 1st polarizer part, 1b 2nd polarizer part, 1e Liquid crystal polarizer, 2 Optical system, 2a Transmission light imaging lens, 2b Reflection light imaging lens, 2c Birefringence imaging lens, 2d Connection Image lens, 3a Transmitted light detector, 3b Reflected light detector, 4 Signal processing device, 6 Pre-stage lens, 8 Prism, 9 Mirror, 10 Birefringence member, 11 Gyro sensor (Tilt detection means), 12 Attitude control device (Tilt) Correction means), 13 non-radiating material, 14a transmitted light wavelength filter, 14b reflected light wavelength filter, 15 micro-rotation device, 16 4-split prism (multi-split prism), 17 polarizer control device, 18 image rotation device, 21 polarizer Surface, 51 wedge-shaped polarizer.

Claims (21)

A polarizer for separating the plane polarized light perpendicular to light rays entering morphism each other, an optical system including an imaging lens for forming an image for each separate said plane polarized light at the polarizer, formed by the optical system An imaging device comprising: a detector that converts the two images into electrical signals corresponding to the respective images; and a signal processing device that processes the electrical signals converted by the detector ,
The polarizer is arranged so that the direction of the plane polarized light is a direction parallel to the ground plane or a direction orthogonal to the ground plane,
With inclination with respect to the ground plane is detected by the inclination detection means, the plane-polarized light by the tilt correcting means for correcting the inclination parallel to the horizontal plane, or corrected to a horizontal plane perpendicular, the two An imaging apparatus, wherein a target is discriminated from a background based on a difference between the electrical signals corresponding to each of images . An imaging system comprising: an optical system including an imaging lens; a detector that converts an image formed by the optical system and a polarizer into an electrical signal; and a signal processing device that processes the electrical signal converted by the detector. A device,
The polarizer is arranged so that light rays incident on the polarizer are separated into mutually orthogonal plane polarization components, and the direction of the plane polarization is parallel to the ground plane or orthogonal to the ground plane. , Two images corresponding to each of the separated plane polarization components are formed by the optical system and the polarizer,
The inclination detecting means detects the inclination with respect to the ground plane, and the inclination correcting means for correcting the inclination corrects the plane polarized light so that it is parallel to or perpendicular to the ground plane. An imaging apparatus, wherein a target is discriminated from a background based on a difference between the electrical signals corresponding to each of images . The optical system further comprises an afocal lens provided in front of the polarizer, the imaging apparatus according to claim 2, characterized in that the polarizer is arranged in front of the imaging lens . The imaging device according to any one of claims 1 to 3 , wherein the polarizer is configured to separate incident light into transmitted plane polarized light and reflected plane polarized light. The imaging apparatus according to claim 4 , wherein the polarizer has a wedge-shaped cross section. The imaging apparatus according to claim 4 , wherein the polarizer has an incident surface to the polarizer and an exit surface from the polarizer perpendicular to the principal ray. A prism that divides incident light into two, a first polarizer that transmits one of the two light beams divided into plane polarized light, and transmits the other of the two light beams divided into the plane. 2 corresponding to each of the second and second light beams transmitted through the first polarizer and the second polarizer, respectively, which are polarized into plane polarized light orthogonal to the polarized light. An optical system including an imaging lens for forming one image, a detector for converting two images formed by the optical system into electrical signals corresponding to the respective images, and an electrical signal converted by the detector An imaging device comprising a signal processing device for processing,
The first polarizer section and the second polarizer section are arranged such that the direction of the plane polarized light is a direction parallel to the ground plane or a direction orthogonal to the ground plane,
The inclination detecting means detects the inclination with respect to the ground plane, and the inclination correcting means for correcting the inclination corrects the plane polarized light so that it is parallel to or perpendicular to the ground plane. An imaging apparatus, wherein a target is discriminated from a background based on a difference between the electrical signals corresponding to each of two images . A mirror that divides an incident light beam into two, a first polarizer that transmits one of the two light beams divided into plane polarized light, and transmits the other of the two light beams divided into the plane. a second polarizer unit for polarized in the plane polarized light orthogonal to the polarization, corresponding to each of the first polarizer unit and the second light polarizer unit the one that passes through each and the other light beam An optical system including an imaging lens that forms two images, a detector that converts the two images formed by the optical system into electrical signals corresponding to the respective images, and an electrical signal converted by the detector An imaging device comprising a signal processing device for processing
The first polarizer section and the second polarizer section are arranged such that the direction of the plane polarized light is a direction parallel to the ground plane or a direction orthogonal to the ground plane,
The inclination detecting means detects an inclination with respect to the ground plane, and the inclination correcting means for correcting the inclination corrects the plane polarized light so that it is parallel to or perpendicular to the ground plane. An imaging apparatus, wherein a target is discriminated from a background based on a difference between the electrical signals corresponding to each of two images . Polarizer, the imaging apparatus according to any one of claims 1 to 3 is a prism having a different refractive index by the polarization direction. Each of plane-polarized light perpendicular to each other in a direction perpendicular to the horizontal plane parallel to the direction or the horizontal plane, the preceding claims, characterized in that is adapted to be converted into an electrical signal by the same detector The imaging apparatus according to any one of 9 . An optical system for forming an image from incident light, which is composed of a birefringent material having a different refractive index depending on the polarization direction , and the anomalous optical axis of the birefringent material is parallel to or perpendicular to the ground plane. Two images corresponding to an optical system including an imaging lens arranged and a polarization component parallel to the abnormal optical axis and a polarization component perpendicular to the abnormal optical axis formed by the optical system are converted into electric signals corresponding to the two images, respectively. An imaging device comprising a detector and a signal processing device that processes an electrical signal obtained by the detector,
An imaging apparatus, wherein a target is discriminated from a background based on a difference between the electrical signals corresponding to the two images . The imaging apparatus according to any one of claims 1 to 10 , wherein the inclination detection means detects an inclination with respect to a ground plane from a captured image. The imaging apparatus according to claim 12 , wherein a horizon line or a horizontal line is detected from a captured image. Inclination correcting means according to claim 1 to claim 7, characterized in that a rotating mechanism for rotating the polarizer according to claim 9, claim 10, claim 12, the imaging apparatus according to claim 13 . Inclination correcting means, wherein characterized in that an image rotation device for rotating the imaging of front incident on the polarizer claims 1 to 7, claim 9, claim 10, claim 12, claim 13 The imaging device according to any one of the above. 16. The imaging apparatus according to claim 1, wherein a wavelength filter is provided in the optical path. The imaging device according to claim 16 , wherein the wavelength filter is capable of changing a transmission band. Above incident light ray direction opposite to the direction in which the reflected is incident on the polarizer, the imaging apparatus according to claim 1, characterized in that nonradiative radiationless body is disposed. The direction of the direction in which light rays on SL incident is reflected is incident on the polarizer side opposite the imaging apparatus according to claim 1, characterized in that the non-polarizing body having no polarization characteristics are arranged . Opposite direction to the direction in which light rays the incident is reflected is incident on the polarizer, according to claim 1, characterized in that uniform polarization of uniform polarization characteristics are arranged over the entire area Imaging device. Opposite direction to the direction in which light rays the incident is reflected is incident on the polarizer, in claim 1, characterized in that temporal changes little unchanged polarization of the polarization characteristics are arranged The imaging device described.

Images