JP2024138784A - Optical image forming apparatus, control method for optical image forming apparatus, and program - Google Patents

Abstract

To provide a new technique to acquire an OCT image and an SLO image while minimizing increase in the size of an apparatus.SOLUTION: An optical image formation apparatus includes an interference optical system, a shielding member, a spectroscopic member, an image sensor, a tomographic image formation unit, and a frontal image formation unit. The interference optical system irradiates a measurement object with measurement light deflected by an optical scanner, and makes reference light passing through a reference optical path interfere with return light of the measurement light from the measurement object. The spectroscopic member splits the interference light between the reference light and the return light in a state where the shielding member is retracted from the reference optical path, or splits the return light in a state where the shielding member is arranged in the reference optical path. The image sensor receives the light split by the spectroscopic member. The tomographic image formation unit forms a tomographic image of the measurement object on the basis of the light reception result of the light obtained by splitting the interference light. The frontal image formation unit forms the frontal image of the measurement object on the basis of the light reception result of the light obtained by splitting the return light.SELECTED DRAWING: Figure 2

Description

The present invention relates to an optical image forming device, a control method for an optical image forming device, and a program.

Optical coherence tomography (OCT) is known as one of the techniques for acquiring optical images. OCT is a technology that uses the coherence of light to image the inside of a sample, and has been put to practical use in a variety of fields, including medical imaging and non-destructive testing.

On the other hand, a method is also known in which a front image of a sample is obtained as an optical image by scanning the sample two-dimensionally with laser light.

For example, Patent Document 1 discloses an ophthalmologic imaging device equipped with an OCT optical system and an SLO (Scanning Laser Ophthalmoscope) optical system. The OCT optical system is configured to perform an OCT scan on the subject's eye as a sample to obtain an OCT image. The SLO optical system is configured to obtain an SLO image by irradiating the subject's eye as a sample with laser light and detecting the return light.

JP 2017-29483 A

However, the technique disclosed in Patent Document 1 has few optical elements that are shared between the OCT optical system and the SLO optical system, which leads to high costs and a large device size.

The present invention was made in consideration of these circumstances, and one of its objectives is to provide a new technology for acquiring OCT images and SLO images while minimizing the increase in size of the device.

One aspect of some embodiments is an optical image forming device including an optical scanner, an interference optical system that splits low-coherence light from a light source into measurement light and reference light, irradiates the measurement light deflected by the optical scanner onto a measured object, and causes the reference light that has passed through a reference optical path to interfere with the return light of the measurement light from the measured object; a shielding member that can be inserted into and removed from the reference optical path; a spectroscopic member that disperses the interference light between the reference light and the return light generated by the interference optical system when the shielding member is retracted from the reference optical path, or disperses the return light output from the interference optical system when the shielding member is disposed in the reference optical path; an image sensor that receives the light dispersed by the spectroscopic member; a tomographic image forming unit that forms a tomographic image of the measured object based on the light reception result of the light obtained by the image sensor that has been dispersed from the interference light; and a front image forming unit that forms a front image of the measured object based on the light reception result of the light obtained by the image sensor that has been dispersed from the return light.

Another aspect of some embodiments is a method for controlling an optical imaging device, the method including an interference optical system including an optical scanner, which splits low-coherence light from a light source into measurement light and reference light, irradiates the measurement light deflected by the optical scanner onto an object to be measured, and causes interference between the reference light that has passed through a reference optical path and return light of the measurement light from the object to be measured, a shielding member that can be inserted into and removed from the reference optical path, a spectroscopic element that spectroscopically separates the interference light between the return light generated by the interference optical system and the reference light, or the return light output from the interference optical system, and an image sensor that receives the light dispersed by the spectroscopic element. The control method for the optical image forming device includes a first interference optical system control step of causing the interference optical system to generate the interference light by retracting the shielding member from the reference optical path, a tomographic image forming step of forming a tomographic image of the object to be measured based on the light reception result obtained by receiving the light obtained by splitting the interference light by the image sensor, a second interference optical system control step of causing the interference optical system to output the return light by inserting the shielding member into the reference optical path, and a front image forming step of forming a front image of the object to be measured based on the light reception result obtained by receiving the light obtained by splitting the return light by the image sensor.

Yet another aspect of some embodiments is a program that causes a computer to execute each step of the above-mentioned optical image forming device control method.

The present invention provides a new technology for acquiring OCT images and SLO images while minimizing the increase in size of the device.

1 is a schematic diagram illustrating an example of a configuration of an optical system of an ophthalmic apparatus according to an embodiment. 1 is a schematic diagram illustrating an example of a configuration of an optical system of an ophthalmic apparatus according to an embodiment. 2 is a schematic diagram illustrating an example of a configuration of a control system of an ophthalmic apparatus according to an embodiment. 2 is a schematic diagram illustrating an example of a configuration of a control system of an ophthalmic apparatus according to an embodiment. 3A and 3B are schematic diagrams for explaining the operation of the ophthalmologic apparatus according to the embodiment. 3A and 3B are schematic diagrams for explaining the operation of the ophthalmologic apparatus according to the embodiment. 3A and 3B are schematic diagrams for explaining the operation of the ophthalmologic apparatus according to the embodiment. 3A and 3B are schematic diagrams for explaining the operation of the ophthalmologic apparatus according to the embodiment. 3A and 3B are schematic diagrams for explaining the operation of the ophthalmologic apparatus according to the embodiment. 4 is a flowchart illustrating an example of an operation of the ophthalmologic apparatus according to the embodiment. 4 is a flowchart illustrating an example of an operation of the ophthalmologic apparatus according to the embodiment. 3A and 3B are schematic diagrams for explaining the operation of the ophthalmologic apparatus according to the embodiment. 3A and 3B are schematic diagrams for explaining the operation of the ophthalmologic apparatus according to the embodiment. 3A and 3B are schematic diagrams for explaining the operation of the ophthalmologic apparatus according to the embodiment.

An example of an embodiment of the optical image forming device, the control method for the optical image forming device, and the program according to the present invention will be described in detail with reference to the drawings. Note that in the embodiment, it is possible to arbitrarily use the techniques described in the documents cited in this specification.

The optical image forming device according to the embodiment includes an interference optical system, a shielding member, a spectroscopic member, an image sensor, a tomographic image forming unit, and a front image forming unit. The interference optical system includes an optical scanner, divides low-coherence light from a light source into measurement light and reference light, irradiates the measurement light deflected by the optical scanner onto the object to be measured, and causes interference between the reference light passing through the reference optical path and the return light of the measurement light from the object to be measured. The shielding member is insertable and detachable from the reference optical path. The spectroscopic member disperses the interference light between the reference light and the return light generated by the interference optical system when the shielding member is retracted from the reference optical path, or disperses the return light output from the interference optical system when the shielding member is disposed in the reference optical path. The image sensor receives the light dispersed by the spectroscopic member (the above-mentioned interference light or the return light of the measurement light). The tomographic image forming unit forms a tomographic image (OCT image) of the object to be measured based on the light reception result of the light obtained by dispersing the interference light obtained by the image sensor. The front image forming unit forms a front image (SLO image) of the object to be measured based on the light reception results of the light obtained by the image sensor after splitting the return light.

The interference optical system is configured to output interference light between the reference light and return light of the measurement light from the object to be measured, or return light of the measurement light from the object to be measured, by using a shielding member that is inserted into and removed from the reference light path. Specifically, when the shielding member is retracted from the reference light path, an interference means (e.g., a fiber coupler) that causes interference between the reference light and return light of the measurement light from the object to be measured outputs interference light between the reference light and the return light. On the other hand, when a shielding member is placed in the reference light path, there is no amount of reference light to interfere, and the interference means outputs the return light of the measurement light as is, without interfering with the reference light and the return light. In other words, the output light of the interference optical system is interference light or return light of the measurement light.

This allows at least a portion of the interference optical system to be shared between the OCT optical system and the SLO optical system by inserting and removing the shielding member. Therefore, it is possible to provide an optical imaging device for acquiring tomographic images and frontal images while minimizing the increase in size of the device.

In some embodiments, the spectroscopic member is a diffraction grating, and the image sensor is a line sensor in which two or more light receiving elements are arranged in a direction corresponding to the arrangement direction of the grating pattern formed on the diffraction grating. In some embodiments, the front image forming unit forms two or more front images as spectral images by assigning pixel information corresponding to each of the two or more light receiving elements to each pixel of each front image. In some embodiments, the front image forming unit forms two or more front images as spectral images by assigning pixel information corresponding to a binning process result for multiple light receiving results in the two or more light receiving elements to each pixel of each front image. Spectroscopic images include hyperspectral images and multispectral images.

Here, the binning process may be a pixel binning process or a data binning process. The pixel binning process is a process in which two or more detection results obtained by two or more light receiving elements are combined inside the image sensor. The data binning process is a process in which two or more detection results obtained by two or more light receiving elements are combined outside the image sensor.

In some embodiments, the front image forming unit forms a single front image by assigning pixel information corresponding to the binning process results for all light receiving results from two or more light receiving elements to each pixel.

Examples of objects to be measured include biological tissues such as eyes and skin, tissues such as teeth, objects to be inspected in non-destructive or non-contact inspection, or objects to be measured in non-invasive measurements. The tomographic image forming unit may form OCT images other than tomographic images (for example, en-face images such as C-scan images and projection images).

The information processing device according to the embodiment realizes the above-mentioned method for controlling the optical image forming device by software processing. The information processing method according to the embodiment includes one or more steps executed by the above-mentioned information processing device. The program according to the embodiment causes a computer (processor) to execute each step of the method for controlling the optical image forming device according to the embodiment. The recording medium according to the embodiment is a computer-readable non-transitory recording medium (storage medium) on which the program according to the embodiment is recorded (stored).

In this specification, a processor includes circuits such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), and a programmable logic device (e.g., an SPLD (Simple Programmable Logic Device), a CPLD (Complex Programmable Logic Device), and an FPGA (Field Programmable Gate Array)). The processor realizes the functions of the embodiment by, for example, reading and executing a program stored in a memory circuit or a storage device. A memory circuit or a storage device may be included in the processor. Additionally, the memory circuit or storage device may be provided outside the processor.

In the following embodiment, the object to be measured is an eye, and the optical image forming device according to the embodiment is an ophthalmic device capable of performing OCT imaging and SLO imaging of the eye. However, the optical image forming device according to the embodiment is not limited to an ophthalmic device.

The ophthalmic device according to the embodiment may further have one or more functions of a fundus camera, a slit lamp ophthalmoscope, a surgical microscope, etc. The ophthalmic device according to the embodiment may further include one or more of an ophthalmic measurement device and an ophthalmic treatment device. The ophthalmic measurement device is, for example, one or more of an eye refraction examination device, a tonometer, a specular microscope, a wavefront analyzer, a perimeter, a microperimeter, etc. The ophthalmic treatment device is, for example, one or more of a laser treatment device, a surgical device, a surgical microscope, etc.

In the following embodiment, the ophthalmologic apparatus includes an interference optical system shared between OCT imaging and SLO imaging, and a fundus camera. This OCT imaging is achieved by spectral domain OCT.

In the following, the x direction is the direction perpendicular to the optical axis direction of the objective lens (left-right direction, horizontal direction), the y direction is the direction perpendicular to the optical axis direction of the objective lens (up-down direction, vertical direction), and the z direction is the optical axis direction of the objective lens.

<Configuration>
[Optical system]
As shown in FIG. 1, the ophthalmic apparatus 1 includes a fundus camera unit 2, an optical image forming unit 100, and an arithmetic and control unit 200. The fundus camera unit 2 is provided with an optical system and a mechanism for acquiring a front image of the subject's eye E (a front image different from an SLO image described later). The optical image forming unit 100 is provided with a part of the optical system and a mechanism for performing OCT. The other part of the optical system and a mechanism for performing OCT is provided in the fundus camera unit 2. The arithmetic and control unit 200 includes one or more processors for performing various calculations and controls. In addition to these, any elements or units such as a member for supporting the subject's face (such as a chin rest or a forehead rest) and a lens unit for switching the target site of OCT (for example, an attachment for anterior segment OCT) may be provided in the ophthalmic apparatus 1.

In some embodiments, the ophthalmic device 1 includes a display device 3. The display device 3 displays the processing results (e.g., OCT images, etc.) by the arithmetic control unit 200, images obtained by the fundus camera unit 2, operation guidance information for operating the ophthalmic device 1, etc.

[Fundus camera unit 2]
The fundus camera unit 2 is provided with an optical system for photographing the fundus Ef of the subject's eye E. The acquired image of the fundus Ef (called a fundus image, fundus photograph, etc.) is a front image such as an observation image or a photographed image. The observation image is obtained by video shooting using near-infrared light. The photographed image is a still image using flash light. Furthermore, the fundus camera unit 2 can photograph the anterior segment Ea of the subject's eye E to acquire a front image (anterior segment image).

The fundus camera unit 2 includes an illumination optical system 10 and an imaging optical system 30. The illumination optical system 10 irradiates illumination light onto the subject's eye E. The imaging optical system 30 detects return light from the subject's eye E. The return light from the subject's eye E is scattered light (reflected light) of the illumination light incident on the subject's eye E. In some embodiments, the return light from the subject's eye E includes scattered light (reflected light) of the illumination light incident on the subject's eye E, and fluorescence and its scattered light excited by the illumination light incident on the subject's eye E.

The measurement light from the optical image forming unit 100 is guided to the test eye E through an optical path within the fundus camera unit 2, and the return light is guided to the optical image forming unit 100 through the same optical path.

The light (observation illumination light) output from the observation light source 11 of the illumination optical system 10 is reflected by the reflection mirror 12 having a curved reflecting surface, passes through the condenser lens 13, and passes through the visible cut filter 14 to become near-infrared light. Furthermore, the observation illumination light is once focused near the photographing light source 15, reflected by the mirror 16, and passes through the relay lenses 17 and 18, the aperture 19, and the relay lens 20. The observation illumination light is then reflected at the periphery (area surrounding the hole) of the aperture mirror 21, passes through the dichroic mirror 46, and is refracted by the objective lens 22 to illuminate the subject's eye E (fundus Ef or anterior eye Ea). The return light from the subject's eye E is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through the hole formed in the central area of the aperture mirror 21, passes through the dichroic mirror 55, passes through the photographing focusing lens 31, and is reflected by the mirror 32. Furthermore, this return light passes through the half mirror 33A, is reflected by the dichroic mirror 33, and is imaged on the light receiving surface of the image sensor 35 by the imaging lens 34. The image sensor 35 detects the return light at a predetermined frame rate. The display device 3 displays an image based on the output from the image sensor 35 (e.g., an anterior eye observation image or a fundus observation image). The focus of the imaging optical system 30 is adjusted to match the fundus Ef or the anterior eye Ea.

The light output from the imaging light source 15 (imaging illumination light) is irradiated onto the fundus Ef via the same path as the observation illumination light. The return light from the subject's eye E is guided to the dichroic mirror 33 via the same path as the observation illumination light, passes through the dichroic mirror 33, is reflected by the mirror 36, and is imaged by the focusing lens 37 on the light receiving surface of the image sensor 38.

The display device 3 displays an image (observation image) based on the fundus reflected light detected by the image sensor 35. When the focus of the photographing optical system 30 is adjusted to the anterior segment, an observation image of the anterior segment of the subject's eye E is displayed. The display device 3 also displays an image (photographed image) based on the fundus reflected light detected by the image sensor 38. The display device 3 that displays the observation image and the display device 3 that displays the photographed image may be the same or different. When the subject's eye E is illuminated with infrared light and a similar photograph is performed, an infrared photographed image is displayed.

The LCD (Liquid Crystal Display) 39 displays a fixation target and a visual target for visual acuity measurement. A part of the light beam output from the LCD 39 is reflected by the half mirror 33A, reflected by the mirror 32, passes through the photographing focusing lens 31, passes through the dichroic mirror 55, and passes through the hole of the aperture mirror 21. The light beam that passes through the hole of the aperture mirror 21 passes through the dichroic mirror 46, is refracted by the objective lens 22, and is projected onto the fundus Ef.

By changing the display position of the fixation target on the screen of the LCD 39, the fixation position of the subject's eye E can be changed. Examples of fixation positions include a fixation position for acquiring an image centered on the macula, a fixation position for acquiring an image centered on the optic disc, a fixation position for acquiring an image centered on the center of the fundus between the macula and the optic disc, and a fixation position for acquiring an image of a site far removed from the macula (periphery of the fundus). In some embodiments, the ophthalmic device 1 includes a GUI (Graphical User Interface) or the like for specifying at least one of such fixation positions. In some embodiments, the ophthalmic device 1 includes a GUI or the like for manually moving the fixation position (display position of the fixation target).

The configuration for presenting a movable fixation target to the subject's eye E is not limited to a display device such as an LCD. For example, a movable fixation target can be generated by selectively turning on multiple light sources in a light source array (such as a light emitting diode (LED) array). Also, a movable fixation target can be generated by one or more movable light sources.

The fundus camera unit 2 is provided with an alignment optical system 50 and a focus optical system 60. The alignment optical system 50 generates an index (alignment index) for positioning (aligning) the device optical system with respect to the subject's eye E. The focus optical system 60 generates an index (split index) for focusing on the subject's eye E.

The light (alignment light) output from the LED 51 of the alignment optical system 50 passes through the aperture 52, the aperture 53, and the relay lens 54, and is reflected by the dichroic mirror 55. The light reflected by the dichroic mirror 55 passes through the hole of the aperture mirror 21, transmits the dichroic mirror 46, and is projected onto the subject's eye E by the objective lens 22. The return light of the alignment light (for example, corneal reflected light or fundus reflected light) passes through the objective lens 22, the dichroic mirror 46, and the hole of the aperture mirror 21, and transmits the dichroic mirror 55. The return light that transmits the dichroic mirror 55 passes through the photographing focusing lens 31, is reflected by the mirror 32, transmits the half mirror 33A, is reflected by the dichroic mirror 33, and is imaged on the light receiving surface of the image sensor 35 by the imaging lens 34. The light image (alignment index) received by the image sensor 35 is displayed on the display device 3 together with the observed image. Manual alignment or automatic alignment is performed based on the alignment index.

The focus optical system 60 generates a split index used for focus adjustment of the subject's eye E. The focus optical system 60 is moved along the optical path (illumination optical path) of the illumination optical system 10 in conjunction with the movement of the photographing focusing lens 31 along the optical path (photographing optical path) of the photographing optical system 30. The reflecting rod 67 can be inserted into and removed from the illumination optical path. When performing focus adjustment, the reflecting surface of the reflecting rod 67 is tilted and positioned in the illumination optical path. The focus light output from the LED 61 passes through the relay lens 62, is separated into two light beams by the split index plate 63, passes through the two-hole diaphragm 64, is reflected by the mirror 65, and is once imaged and reflected on the reflecting surface of the reflecting rod 67 by the condenser lens 66. Furthermore, the focus light passes through the relay lens 20, is reflected by the aperture mirror 21, passes through the dichroic mirror 46, is refracted by the objective lens 22, and is projected onto the fundus Ef. The fundus reflection of the focusing light is guided to the image sensor 35 via the same path as the return light of the observation illumination light. Manual focusing and autofocusing can be performed based on the received light image (split target image).

The image sensor 35 acquires two split index images formed by the focus optical system 60. In manual focus or autofocus, the position of the imaging focusing lens 31 is moved so that the two split index images have a predetermined positional relationship. In some embodiments, the OCT focusing lens 43 is moved to a position corresponding to the position on the optical path of the imaging focusing lens 31 in the imaging optical system 30. In some embodiments, the OCT focusing lens 43 is moved in the optical axis direction in conjunction with the movement of the imaging focusing lens 31.

The dichroic mirror 46 combines the optical path for fundus photography with the optical path for OCT. The dichroic mirror 46 reflects light in the wavelength band used for OCT and transmits light for fundus photography. The optical path for OCT (optical path for measurement light) includes, in order from the optical image forming unit 100 side to the dichroic mirror 46 side, a collimator lens unit 40, an optical path length changer 41, an optical scanner 42, an OCT focusing lens 43, a mirror 44, and a relay lens 45.

The optical path length change unit 41 can move in the direction of the arrow shown in FIG. 1 to change the length of the optical path for OCT. This change in optical path length is used for correcting the optical path length according to the axial length of the eye and adjusting the interference state. The optical path length change unit 41 includes a corner cube and a mechanism for moving it.

The optical scanner 42 is aligned to be positioned optically conjugate with the pupil of the subject's eye E or in its vicinity. The optical scanner 42 deflects the measurement light LS passing through the OCT optical path. The optical scanner 42 is, for example, a galvano scanner capable of one-dimensional scanning or two-dimensional scanning.

The OCT focusing lens 43 is moved along the optical path of the measurement light LS to adjust the focus of the OCT optical system. The movement of the imaging focusing lens 31, the movement of the focus optical system 60, and the movement of the OCT focusing lens 43 can be controlled in a coordinated manner.

[Optical imaging unit 100]
Fig. 2 shows an example of the configuration of the optical system of the optical image forming unit 100 in Fig. 1. In Fig. 2, the same parts as in Fig. 1 are given the same reference numerals, and the description thereof will be omitted as appropriate.

The optical imaging unit 100 is provided with an optical system for performing spectral domain OCT. This optical system includes an interference optical system. This interference optical system has a function of splitting light (low coherence light) from a broadband light source (low coherence light source) into measurement light and reference light, and a function of superimposing the return light of the measurement light from the subject's eye E and the reference light that has passed through the reference light path. The detection result (detection signal) of the output light from the interference optical system is a signal indicating the spectrum of the output light, and is sent to the arithmetic and control unit 200. Note that although the interferometer included in the optical imaging unit 100 in this example is a Michelson type, another type of interferometer (for example, a Mach-Zehnder type interferometer) may also be used.

The light source unit 101 includes a broadband light source and outputs broadband low-coherence light L0. The low-coherence light L0 includes, for example, a wavelength band in the near-infrared region (approximately 800 nm to 900 nm) and has a temporal coherence length of approximately several tens of micrometers. Note that a wavelength band that cannot be seen by the human eye, for example, near-infrared light having a central wavelength of approximately 1040 to 1060 nm, may be used as the low-coherence light L0. The light source unit 101 includes any light output device, for example, any of a superluminescent diode (SLD), an LED, and a semiconductor optical amplifier (SOA). The low-coherence light L0 may also be light including a wavelength band suitable for SLO imaging, such as a central wavelength of 488 nm, 514 nm, 633 nm, or 780 nm.

The low-coherence light L0 output from the light source unit 101 is guided by the optical fiber 102 to the fiber coupler 103, where it is split into the measurement light LS and the reference light LR.

The reference light LR generated by the fiber coupler 103 is guided through the optical fiber 104 to the attenuator 105 where its light amount is adjusted, and then to the polarization controller 106 where its polarization state is adjusted and then to the collimator lens unit 107. The attenuator 105 adjusts the light amount of the reference light LR under the control of the arithmetic and control unit 200 described below. The polarization controller 106 adjusts the polarization state of the reference light LR under the control of the arithmetic and control unit 200 described below.

The reference light LR converted into a parallel light beam by the collimating lens unit 107 is guided to the reference mirror 108 via a mirror or the like as necessary. The reference mirror 108 is configured to be movable along the optical path of the reference light LR. For example, the reference mirror 108 is driven by a reference drive unit (not shown) controlled by the arithmetic control unit 200 described below. This changes the optical path length of the reference light LR. The reference light LR reflected by the reference mirror 108 enters the collimating lens unit 107 and is guided to the fiber coupler 103 via the polarization controller 106 and the attenuator 105. The optical path of the reference light LR from the fiber coupler 103 to the reference mirror 108 corresponds to the reference optical path (reference arm).

In this embodiment, the shielding member 130 can be inserted and removed between the collimator lens unit 107 and the reference mirror 108. The shielding member 130 is inserted and removed from the optical path of the reference light LR by a shielding mechanism (not shown) controlled by the arithmetic and control unit 200 described below.

On the other hand, the measurement light LS generated by the fiber coupler 103 is guided to the collimating lens unit 40 through the optical fiber 109 and emitted as parallel light. The exit end (entrance end) of the optical fiber 109 connected to the collimating lens unit 40 is aligned to be optically conjugate with the measurement site of the test eye E (e.g., the fundus Ef) or in its vicinity. The parallel light emitted from the exit end of the collimating lens unit 40 is guided to the dichroic mirror 46 via the optical path length change unit 41, the optical scanner 42, the OCT focusing lens 43, the mirror 44, and the relay lens 45. The parallel light guided to the dichroic mirror 46 is reflected by the dichroic mirror 46, refracted by the objective lens 22, and projected onto the test eye E. The measurement light LS is scattered and reflected at various depth positions of the test eye E (especially the fundus Ef) to generate backscattered light. The return light of the measurement light LS from the test eye E travels in the opposite direction along the same path as the outward path and is guided to the fiber coupler 103.

When the shielding member 130 is placed in the optical path of the reference light LR, the reference light LR is blocked by the shielding member 130. At this time, the reference light LR from the collimating lens unit 107 does not reach the fiber coupler 103, and the return light of the measurement light LS from the collimating lens unit 40 is emitted directly from the fiber coupler 103 through the optical fiber 110 and from the output end 111. The return light of the measurement light LS emitted from the output end 111 is converted into parallel light by the collimating lens 112.

When the shielding member 130 is removed from the optical path of the reference light LR, the reference light LR is guided to the reference mirror 108. At this time, the reference light LR is reflected by the reference mirror 108, enters the collimating lens unit 107, passes through the polarization controller 106 and the attenuator 105, and is guided to the fiber coupler 103 through the optical fiber 104. The fiber coupler 103 generates interference light LC by superimposing the reference light LR, which has been reflected by the reference mirror 108 and passed through the reference optical path, and the return light of the measurement light LS. The interference light LC is output from the output end 111 of the optical fiber 110, and is converted into parallel light by the collimating lens 112.

That is, the return light of the measurement light LS from the test eye E or the interference light LC is emitted from the output end 111 of the optical fiber 110 as output light of the interference optical system.

A diffraction grating 113 is disposed in the optical path of the output light converted into parallel light by the collimating lens 112. The diffraction grating 113 separates the return light of the interference light LC or the measurement light LS converted into parallel light by the collimating lens 112. The light separated by the diffraction grating 113 is focused on the light receiving surface of the image sensor 115 by the condenser lens 114.

The image sensor 115 is a photodetector. In this embodiment, the image sensor 115 is, for example, a line sensor in which two or more light receiving elements are arranged in a direction corresponding to the arrangement direction of the grating pattern formed on the diffraction grating 113. In some embodiments, the image sensor 115 is an area sensor. The image sensor 115 detects multiple spectral components (wavelength components) of the interference light LC or the return light of the measurement light LS separately using a light receiving element array to generate a detection signal (detection data). The generated detection signal is sent to the arithmetic and control unit 200. As described later, the arithmetic and control unit 200 forms an OCT image such as a tomographic image of the subject's eye E or an SLO image such as a front image based on the detection signal acquired by the image sensor 115, and displays it on the display device 3.

In this embodiment, the ophthalmic apparatus 1 operates in multiple operation modes using the optical image forming unit 100. The multiple operation modes include an OCT image acquisition mode for acquiring OCT images such as tomographic images, and an SLO image acquisition mode for acquiring SLO images such as frontal images.

In this example, a case has been described in which the optical path length change unit 41 can change the length of the optical path (measurement optical path, measurement arm) of the measurement light LS, and the reference mirror 108 can change the length of the optical path (reference optical path, reference arm) of the reference light LR. However, the configuration according to the embodiment is not limited to this. For example, the length of one of the optical paths of the measurement light LS and the reference light LR may be changed. It is also possible to change the difference between the measurement optical path length and the reference optical path length using optical components other than these.

[Control system]
3 and 4 show an example of the configuration of the control system (processing system) of the ophthalmic apparatus 1. Some of the components included in the ophthalmic apparatus 1 are omitted in FIGS. 3 and 4. FIG. 3 shows an example of a functional block diagram of the control system of the ophthalmic apparatus 1. In FIG. 3, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. FIG. 4 shows an example of a functional block diagram of the image forming unit 220 in FIG. 3.

The control unit 210, image forming unit 220 and data processing unit 230 are provided, for example, in the arithmetic control unit 200.

(Control unit 210)
The control unit 210 executes various types of control and includes a main control unit 211 and a storage unit 212.

(Main control unit 211)
The main controller 211 includes a processor (e.g., a control processor) and controls each part (including each element shown in Fig. 1 and Fig. 2) of the ophthalmic apparatus 1. For example, the main controller 211 controls each part of the optical system of the fundus camera unit 2 shown in Fig. 1 and Fig. 2, each part of the optical system of the optical image forming unit 100, the moving mechanism 170 that moves the above optical systems, the image forming unit 220, the data processing unit 230, and a user interface (UI) 240.

The control of the fundus camera unit 2 includes control of the focusing drive units 31A and 43A, control of the image sensors 35 and 38, control of the LCD 39, control of the optical path length change unit 41, and control of the optical scanner 42.

The control of the focusing drive unit 31A includes control to move the imaging focusing lens 31 in the optical axis direction. The control of the focusing drive unit 43A includes control to move the OCT focusing lens 43 in the optical axis direction.

Control of image sensors 35 and 38 includes control of the light receiving sensitivity of the imaging element, control of the frame rate (light receiving timing, exposure time), control of the light receiving area (position, size, dimension), and control of reading out the light receiving results for the imaging element.

The control of the LCD 39 includes control of the fixation position. For example, the main control unit 211 displays a fixation target at a position on the screen of the LCD 39 that corresponds to the fixation position that has been set manually or automatically. The main control unit 211 can also change (continuously or stepwise) the display position of the fixation target displayed on the LCD 39. This makes it possible to move the fixation target (i.e., to change the fixation position). The display position and movement mode of the fixation target are set manually or automatically. Manual setting is performed, for example, using a GUI. Automatic setting is performed, for example, by the data processing unit 230.

The control over the optical path length changing unit 41 includes control to change the optical path length of the measurement light LS. The main control unit 211 controls a drive unit that drives the corner cube of the optical path length changing unit 41 to move the optical path length changing unit 41 along the optical path of the measurement light LS, thereby changing the optical path length of the measurement light LS.

The control of the optical scanner 42 includes control of the scan mode, scan range (scan start position, scan end position), scan speed, etc. By controlling the optical scanner 42, the main controller 211 can perform an OCT scan with the measurement light LS on a desired area in the measurement site (image capture site).

The main control unit 211 can also control the observation light source 11, the imaging light source 15, the alignment optical system 50, the focus optical system 60, etc.

Control over the optical image forming unit 100 includes control over the light source unit 101, control over the attenuator 105, control over the polarization controller 106, control over the reference drive unit 108A, control over the shielding mechanism 130A, and control over the image sensor 115.

Control over the light source unit 101 includes controlling the on and off of the broadband light source included in the light source unit 101, controlling the amount of light emitted from the broadband light source, and controlling the central wavelength of the light emitted from the broadband light source.

The attenuator 105 adjusts the light intensity of the reference light LR under the control of the main control unit 211.

The polarization controller 106 adjusts the polarization state of the reference light LR under the control of the main control unit 211.

The reference driver 108A moves the reference mirror 108 along the optical path of the reference light LR under the control of the main controller 211.

Under the control of the main controller 211, the shielding mechanism 130A inserts and removes the shielding member 130 from the optical path of the reference light LR between the collimator lens unit 107 and the reference mirror 108. The shielding mechanism 130A retracts the shielding member 130 from the optical path of the reference light LR in the OCT image acquisition mode, and places the shielding member 130 in the optical path of the reference light LR in the SLO image acquisition mode.

Control over the image sensor 115 includes control over the light receiving sensitivity of the light receiving elements, control over the frame rate (light receiving timing), control over the light receiving area (position, size, etc.), and control over reading out the light receiving results from the light receiving elements. The control over reading out the light receiving results from the light receiving elements includes control over the selection of the light receiving elements from which the light receiving results are read out.

The moving mechanism 170, for example, moves at least the fundus camera unit 2 (optical system) three-dimensionally. In a typical example, the moving mechanism 170 includes at least a mechanism for moving the fundus camera unit 2 in the x direction (left-right direction), a mechanism for moving in the y direction (up-down direction), and a mechanism for moving in the z direction (depth direction, front-back direction). The mechanism for moving in the x direction includes, for example, an x stage that can move in the x direction, and an x movement mechanism that moves the x stage. The mechanism for moving in the y direction includes, for example, a y stage that can move in the y direction, and a y movement mechanism that moves the y stage. The mechanism for moving in the z direction includes, for example, a z stage that can move in the z direction, and a z movement mechanism that moves the z stage. Each moving mechanism includes a pulse motor as an actuator, and operates under the control of the main control unit 211.

The control of the moving mechanism 170 is used for alignment and tracking. Tracking refers to moving the device optical system in accordance with the eye movement of the subject's eye E. When tracking is performed, alignment and focus adjustment are performed in advance. Tracking is a function that maintains a suitable positional relationship with alignment and focus by making the position of the device optical system follow the eye movement. In some embodiments, the moving mechanism 170 is configured to be controlled to change the optical path length of the reference light (and therefore the optical path length difference between the optical path of the measurement light and the optical path of the reference light).

In the case of manual alignment, a user such as an examiner operates the user interface 240 to move the optical system relative to the subject's eye E so that the displacement of the subject's eye E relative to the optical system is cancelled. For example, the main control unit 211 controls the movement mechanism 170 by outputting a control signal corresponding to the operation content on the user interface 240 to the movement mechanism 170 to move the optical system relative to the subject's eye E.

In the case of auto-alignment, the main controller 211 controls the moving mechanism 170 to move the optical system relative to the subject's eye E so that the displacement of the subject's eye E relative to the optical system is canceled. Specifically, the main controller 211 specifies the position of the received image formed by projecting the light (alignment light) output from the LED 51 of the alignment optical system 50 onto the subject's eye E. The main controller 211 cancels the displacement of the received image relative to a predetermined alignment reference position (e.g., a position corresponding to the optical axis of the optical system) and controls the moving mechanism 170 so that the positional relationship of the subject's eye E relative to the optical system becomes a predetermined positional relationship. In some embodiments, the main controller 211 controls the moving mechanism 170 to move the optical system relative to the subject's eye E by outputting a control signal to the moving mechanism 170 so that the optical axis of the optical system approximately coincides with the axis of the subject's eye E and the distance of the optical system relative to the subject's eye E is a predetermined working distance. Here, the working distance is a preset value also called the working distance of the objective lens 22, and corresponds to the distance between the subject's eye E and the optical system during measurement (photography) using the optical system.

The main controller 211, as a display controller, can display various information on the display unit 241. For example, the main controller 211 displays on the display unit 241 a fundus image or anterior segment image acquired using the fundus camera unit 2, an image acquired using the optical image forming unit 100, or a data processing result (analysis processing result) acquired by the data processing unit 230 described later. Here, the image acquired using the optical image forming unit 100 includes a tomographic image and a front image. The tomographic image is an OCT image that represents the morphology of the subject's eye E in the depth direction. The front image includes an SLO image acquired in the SLO image acquisition mode in addition to an OCT image such as an en-face image acquired in the OCT image acquisition mode. In some embodiments, the main controller 211 causes the display unit 241 to display the data processing result in association with at least one of the fundus image (or anterior segment image), the OCT image, and the SLO image.

(Memory unit 212)
The storage unit 212 stores various data. The functions of the storage unit 212 are realized by a storage device such as a memory or a storage device. Examples of data stored in the storage unit 212 include image data of a fundus image, image data of an anterior eye image, OCT data (including an OCT image), SLO data (including a front image acquired using the optical image forming unit 100), and information on the subject's eye. The information on the subject's eye includes information on the subject such as a patient ID and name, identification information for the left eye/right eye, and information on the subject's eye such as electronic medical record information. The storage unit 212 stores programs for executing various processors (control processor, image forming processor, data processing processor).

(Image forming unit 220)
The image forming section 220 includes a processor (eg, an image forming processor) and forms a tomographic image and a front image of the subject's eye E based on the output (detection data) from the image sensor 115 .

Figure 4 shows a block diagram of an example of the configuration of the image forming unit 220 according to an embodiment.

The image forming unit 220 includes an OCT image forming unit 221 and an SLO image forming unit 222.

The OCT image forming unit 221 forms an OCT image based on the detection data obtained by the image sensor 115. The OCT image includes a tomographic image, an en-face image, etc. The SLO image forming unit 222 forms an SLO image based on the detection data obtained by the image sensor 115. The SLO image includes a front image.

For example, the OCT image forming unit 221 performs signal processing on the spectral distribution based on the OCT data for each A-line to generate a reflection intensity profile (A-line profile) for each A-line, similar to conventional spectral domain OCT. Specifically, the image sensor 115 receives light dispersed by the diffraction grating 113 to detect detection data with equal wavelength intervals for each A-line. The OCT image forming unit 221 acquires detection data with equal wavelength intervals from the image sensor 115 for each A-line, and performs rescaling processing on the acquired detection data to convert it into detection data with equal wavenumber intervals. The OCT image forming unit 221 further performs Fourier transform processing on the detection data converted to equal wavenumber intervals to generate an intensity profile (reflection intensity profile) of the return light (backscattered light) at the incident position of the measurement light LS of the subject's eye E. The signal processing for generating the A-line profile includes the Fast Fourier Transform (FFT) for performing the Fourier transform described above, as well as noise reduction (denoising) and filtering. Furthermore, the OCT image forming unit 221 images each of the generated A-line profiles to generate multiple A-scan image data, and arranges the A-scan image data according to a scan pattern (arrangement of multiple scan points).

For example, the SLO image forming unit 222 is configured to move the irradiation position of the measurement light LS on the subject's eye E by deflecting the measurement light LS with the optical scanner 42, and sequentially acquire detection data from the image sensor 115 that receives the return light of the measurement light LS from each irradiation position. The SLO image forming unit 222 forms an SLO image corresponding to the scan range using the measurement light LS by assigning to each pixel a pixel value corresponding to the detection data from the image sensor 115.

As shown in FIG. 4, such an SLO image forming unit 222 includes a binning processing unit 222A. That is, in this embodiment, data binning processing is performed. However, in the configuration according to the embodiment, pixel binning processing may also be performed.

The binning processing unit 222A performs binning processing on the detection data from the image sensor 115. Here, the binning processing is a process of combining two or more light reception results obtained by two or more light receiving elements. Examples of the process of combining two or more light reception results include addition processing and weighted addition processing. For example, by performing weighted addition processing on two or more light reception results, the light reception results to be subjected to the binning processing may be selected using a weighting coefficient.

The binning processing unit 222A can perform binning processing on some or all of the light reception results (detection data) of two or more light receiving elements included in the image sensor 115. For example, the binning processing unit 222A can perform binning processing on the light reception results of two or more light receiving elements selected from the two or more light receiving elements included in the image sensor 115.

5 is a schematic diagram for explaining a first operation example of the SLO image forming unit 222 according to the embodiment. In Fig. 5, the image sensor 115 is a line sensor in which n (n is an integer of 2 or more) light receiving elements are arranged, and detection data DT (light receiving results _d1 to _dn ) are acquired by the n light receiving elements.

The SLO image forming unit 222 is capable of forming a single SLO image SIMG by assigning pixel information corresponding to the binning processing results for all light receiving results d ₁ to d _n of n light receiving elements (two or more light receiving elements) in the image sensor 115 to each pixel.

Specifically, the binning processing unit 222A executes a binning process of adding, for each pixel, the light receiving results d ₁ to d _n acquired by the n light receiving elements of the image sensor 115. The SLO image forming unit 222 forms an SLO image SIMG by assigning pixel information (pixel value, luminance value) corresponding to the binning process result to each pixel, sequentially from the start position (x, y) = (0, 0) in the image.

Figure 6 is a schematic diagram for explaining a second operation example of the SLO image forming unit 222 according to the embodiment. In Figure 6, parts similar to those in Figure 5 are given the same reference numerals and will be explained as appropriate.

The SLO image forming unit 222 can form n SLO images SIMG 1 to SIMG n by assigning pixel information corresponding to n light receiving results d ₁ to _{d n} of n light receiving elements in the image sensor 115 to each pixel of different SLO images. _The SLO images SIMG ₁ to SIMG _n are hyperspectral images made up of n spectral images corresponding to each wavelength component.

Specifically, the SLO image forming unit 222 assigns pixel information corresponding to the light reception result _d1 in the detection data DT to the SLO image _SIMG1 , assigns pixel information corresponding to the light reception result _d2 to the SLO image SIMG2, ..., assigns pixel information corresponding to the light reception result _dn to the SLO image _SIMGn , for the pixel at the start position (x, y) = (0, 0 ₎ in each image. Next, the SLO image forming unit 222 assigns pixel information corresponding to the light reception result _d1 in the detection data DT to the SLO image _SIMG1 , assigns pixel information corresponding to the light reception result _d2 to the SLO image _SIMG2 , ..., assigns pixel information corresponding to the light reception result _dn to the SLO image _SIMGn, for the next pixel in each image. In this way, by sequentially assigning pixel information corresponding to each of two or more light reception results to each pixel in each SLO image, two or more SLO images can be formed. As a result, a hyperspectral image corresponding to the wavelength components dispersed by the diffraction grating 113 is formed.

Figure 7 is a schematic diagram for explaining a third operation example of the SLO image forming unit 222 according to the embodiment. In Figure 7, parts similar to those in Figure 5 are given the same reference numerals and will be explained as appropriate.

The SLO image forming unit 222 divides the n light receiving elements in the image sensor 115 into multiple light receiving element groups each consisting of two or more adjacent light receiving elements, performs binning processing on the light receiving results of the light receiving elements for each of the multiple light receiving element groups, and assigns pixel information corresponding to the binning processing result to each pixel, thereby forming two or more SLO images as two or more spectral images. For ease of explanation, FIG. 7 shows an example of division into multiple light receiving element groups each consisting of three light receiving elements.

Specifically, the SLO image forming unit 222 performs binning processing by adding each of the light reception results d ₁ to d ₃ in the detection data DT, performs binning processing by adding each of the light reception results d ₄ to d ₆ , ..., performs binning processing by adding each of the light reception results d _n-2 to d _n . The SLO image forming unit 222 sequentially assigns pixel information corresponding to the binning processing results of the light reception results d ₁ to d ₃ to the SLO image SIMG ₁ , assigns pixel information corresponding to the binning processing results of the light reception results d ₄ to d ₆ to the SLO image SIMG ₂ , ..., assigns pixel information corresponding to the binning processing results of the light reception results d _n-2 to d _n to the SLO image SIMG _m (2≦m<n, m is an integer) in each image.

This allows two or more spectral images to be formed for each group of wavelength components.

Figure 8 is a schematic diagram for explaining a fourth operation example of the SLO image forming unit 222 according to the embodiment. In Figure 8, parts similar to those in Figure 5 are given the same reference numerals and will be explained as appropriate.

The SLO image forming unit 222 performs binning processing on the light receiving results of two or more light receiving elements selected from the n light receiving elements in the image sensor 115, and forms a single SLO image by assigning pixel information corresponding to the binning processing result to each pixel. The two or more light receiving elements to be selected may be determined in advance or may be determined ex post by the main control unit 211. For convenience of explanation, in FIG. 8, it is assumed that light receiving results d _p to d _q (1≦p, q≦n, p<q, p and q are integers) have been selected.

Specifically, the binning processing unit 222A performs binning processing by adding, for each pixel, each of the light reception results _dp to _dq among the light reception results _d1 to _dn acquired by the n light receiving elements of the image sensor 115. The SLO image forming unit 222 can form a single SLO image SIMG by assigning, for each pixel, pixel information corresponding to the binning processing results for the light reception results _dp to _dq .

Figure 9 is a schematic diagram for explaining a fifth operation example of the SLO image forming unit 222 according to the embodiment. In Figure 9, parts similar to those in Figure 5 are given the same reference numerals and will be explained as appropriate.

The SLO image forming unit 222 performs binning processing on the light receiving results of two or more light receiving elements selected from the n light receiving elements in the image sensor 115, and forms a single SLO image by assigning pixel information corresponding to the binning processing result to each pixel. The two or more light receiving elements selected may be two or more light receiving elements that are not adjacent to each other and are determined in advance. In addition, the two or more light receiving elements may be determined ex post by the main control unit 211. For convenience of explanation, FIG. 9 assumes that light receiving results d ₁ to d p _-1 and d _q+1 to d _n are selected from the light receiving results d ₁ to d _n , excluding light receiving results d _p to d _q .

Specifically, the binning processing unit 222A performs binning processing by adding each of the light reception results d ₁ to d _p-1 and d _q+1 to d n among the light reception results d ₁ to d _n acquired by the _n light receiving elements of the image sensor 115. The SLO image forming unit 222 can form a single SLO image SIMG by assigning pixel information corresponding to the binning processing results for the light reception results d ₁ to d _p-1 and d _q+1 to d _n to each pixel.

(Data Processing Unit 230)
The data processing unit 230 includes a processor (e.g., a data processor) and performs image processing and analysis processing on the image formed by the image forming unit 220. At least two of the processor included in the main control unit 211, the processor included in the data processing unit 230, and the processor included in the image forming unit 220 may be configured by a single processor.

The data processing unit 230 performs known image processing such as an interpolation process that interpolates pixels between tomographic images to form image data of a three-dimensional image of the fundus Ef or the anterior segment Ea. The image data of a three-dimensional image means image data in which the positions of pixels are defined by a three-dimensional coordinate system. The image data of a three-dimensional image includes image data consisting of three-dimensionally arranged voxels. This image data is called volume data or voxel data. When an image based on the volume data is to be displayed, the data processing unit 230 performs a rendering process (such as volume rendering or MIP (Maximum Intensity Projection)) on the volume data to form image data of a pseudo three-dimensional image as viewed from a specific line of sight. The pseudo three-dimensional image is displayed on a display device such as the display unit 241.

It is also possible to form stack data of multiple tomographic images as image data of a three-dimensional image. Stack data is image data obtained by arranging multiple tomographic images obtained along multiple scan lines three-dimensionally based on the positional relationship of the scan lines. In other words, stack data is image data obtained by expressing multiple tomographic images that were originally defined by separate two-dimensional coordinate systems using a single three-dimensional coordinate system (i.e., embedding them in a single three-dimensional space).

In some embodiments, the data processor 230 generates a B-scan image by arranging the A-scan image in the B-scan direction. In some embodiments, the data processor 230 can perform various renderings on the acquired three-dimensional data set (volume data, stack data, etc.) to form a B-mode image (B-scan image) (longitudinal section image, axial section image) in an arbitrary section, a C-mode image (C-scan image) (transverse section image, horizontal section image), a projection image, a shadowgram, etc. An image of an arbitrary section, such as a B-scan image or a C-scan image, is formed by selecting pixels (pixels, voxels) on a specified section from the three-dimensional data set. A projection image is formed by projecting the three-dimensional data set in a predetermined direction (z direction, depth direction, axial direction). A shadowgram is formed by projecting a part of the three-dimensional data set (for example, partial data corresponding to a specific layer) in a predetermined direction. By changing the depth range of the layer direction to be integrated, two or more different shadowgrams can be formed. Images that are viewed from the front of the subject's eye, such as C-scan images, projection images, and shadowgrams, are called en-face images.

The data processing unit 230 can construct B-scan images and frontal images (vessel-enhanced images, angiograms) in which retinal blood vessels and choroidal blood vessels are emphasized based on data (e.g., B-scan image data) collected in a time series by OCT. For example, time-series OCT data can be collected by repeatedly scanning approximately the same area of the subject's eye E.

In some embodiments, the data processor 230 compares time-series B-scan images obtained by B-scanning approximately the same area, and constructs an enhanced image in which the changed area is emphasized by converting pixel values of the changed area in signal intensity into pixel values corresponding to the change. Furthermore, the data processor 230 extracts information of a predetermined thickness in the desired area from the multiple enhanced images constructed, and constructs it as an en-face image to form an OCTA (angiography) image.

In some embodiments, the data processing unit 230, as an analysis unit, identifies a predetermined layer region in the tomographic image. Examples of the predetermined layer region include the internal limiting membrane, nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, external limiting membrane, photoreceptor layer, retinal pigment epithelium layer, Bruch's membrane, choroid, and sclera.

In some embodiments, the data processing unit 230 identifies a predetermined layer region based on the intensity of the interference signal (detection signal of dispersed light) obtained by the image sensor 115. For example, the data processing unit 230 identifies a position showing an extreme value (maximum value) of the intensity of the interference signal as a position corresponding to the boundary position of the layer region, and identifies the above-mentioned layer region based on the position showing the maximum value of the intensity of the interference signal.

In some embodiments, the data processing unit 230 performs segmentation processing based on the luminance value of each pixel in the tomographic image. That is, each layer region of the fundus Ef has a characteristic reflectance, and the image regions corresponding to these layer regions also have characteristic luminance values. The data processing unit 230 can identify the target image region (layer region) by performing segmentation processing based on these characteristic luminance values.

(User Interface 240)
The user interface 240 receives input from the user to the ophthalmic apparatus 1 and outputs information from the ophthalmic apparatus 1 to the user. The user interface 240 includes a display unit 241 and an operation unit 242.

The display unit 241 displays information under the control of the control unit 210. The display unit 241 includes the display device 3 shown in FIG. 1.

The operation unit 242 is used to operate the ophthalmic device 1. The operation unit 242 includes various hardware keys (joystick, buttons, switches, etc.) provided on the ophthalmic device 1. The operation unit 242 may also include various software keys (buttons, icons, menus, etc.) displayed on a touch panel display screen.

At least a portion of the display unit 241 and the operation unit 242 may be configured as an integrated unit. A typical example of this is a touch panel type display screen.

The ophthalmic device 1 may also include a communication unit for communicating with an external device (not shown). The communication unit has a communication interface according to the connection form with the external device. Examples of external devices include a refractive power measurement device capable of refractive power measurement, or a spectacle lens measurement device for measuring the optical characteristics of a lens. The refractive power measurement device projects light onto the fundus of the subject's eye and receives return light from the subject's eye to obtain a ring image, and can calculate the refractive power value of the subject's eye from the obtained ring image. The spectacle lens measurement device measures the diopter of the spectacle lens worn by the subject, and inputs this measurement data into the ophthalmic device 1. The external device may also be any ophthalmic device, a device (reader) that reads information from a recording medium, or a device (writer) that writes information to a recording medium. Furthermore, the external device may be a hospital information system (HIS) server, a DICOM (Digital Imaging and Communication in Medicine) server, a doctor's terminal, a mobile terminal, a personal terminal, a cloud server, etc.

The subject's eye E is an example of an "object to be measured" according to the embodiment. The optical system included in the optical image forming unit 100 and the optical scanner 42 are an example of an "interference optical system" according to the embodiment. The diffraction grating 113 is an example of a "spectroscopic member" according to the embodiment. The OCT image forming section 221 is an example of a "tomographic image forming section" according to the embodiment. The SLO image forming section 222 is an example of a "front image forming section" according to the embodiment.

<Example of operation>
An example of the operation of the ophthalmologic apparatus 1 according to the embodiment will be described.

FIGS. 10 and 11 show an example of the operation of the ophthalmic device 1. FIG. 10 shows a flow diagram of an example of the operation of the ophthalmic device 1. FIG. 11 shows a flow diagram of an example of the operation of step S11. FIGs. 12, 13, and 14 show explanatory diagrams of the operation of step S12. The memory unit 212 stores a computer program for realizing the processing shown in FIG. 10 and FIG. 11. The main control unit 211 executes the processing shown in FIG. 10 and FIG. 11 by operating according to this computer program.

(S1: Set operation mode)
First, the user designates either the OCT image acquisition mode or the SLO image acquisition mode using the operation unit 242. The main controller 211 receives an operation control signal corresponding to the content of the user's operation on the operation unit 242 and sets the operation mode.

(S2: Set scan conditions)
Next, the main control unit 211 sets the scan conditions. For example, the user specifies the scan conditions using the operation unit 242. The main control unit 211 receives an operation control signal corresponding to the content of the user's operation on the operation unit 242, and sets the scan conditions. The scan conditions include a scan range, a scan mode, a scan speed, and the like.

(S3: Alignment)
Next, with the subject's face fixed on a face receiving portion (not shown), the examiner performs a predetermined operation on the operation portion 242, and the ophthalmic device 1 begins presenting a fixation target to the subject's eye E.

Specifically, the main control unit 211 controls the LCD 39 to display a fixation target pattern representing a predetermined fixation target at a specified position on the screen of the LCD panel 39.

In addition, the ophthalmic device 1 performs alignment when the user performs a specified operation on the operation unit 242.

Specifically, the main controller 211 controls the alignment optical system 50 to project alignment light onto the subject's eye E, and performs manual alignment or auto alignment as described above based on the received light image acquired by the image sensor 35. This causes the optical system shown in FIG. 1 to move to an examination position for the subject's eye E. The examination position is a position where the examination of the subject's eye E can be performed with sufficient accuracy.

The operation of the ophthalmic device 1 proceeds to step S4 in response to an instruction from the main control unit 211 or a user operation or instruction to the operation unit 242.

(S4: Focus adjustment)
Next, the main control unit 211 executes focus adjustment.

Specifically, the main control unit 211 controls the focus optical system 60 to project a split index onto the subject's eye E and perform manual focus or autofocus.

In the case of manual focus, the subject operates the operation unit 242, and the main control unit 211 controls the focus drive unit 31A to move the imaging focusing lens 31 in the optical axis direction so that the two split target images are in a predetermined positional relationship. The OCT focusing lens 43 moves in the optical axis direction in conjunction with the movement of the imaging focusing lens 31.

In the case of autofocus, the main controller 211 controls the focus driver 31A so that the two split index images obtained by the image sensor 35 have a predetermined positional relationship. The main controller 211 then moves the imaging focusing lens 31 in the optical axis direction so that the two split index images have a predetermined positional relationship. The OCT focusing lens 43 moves in the optical axis direction in conjunction with the movement of the imaging focusing lens 31.

(S5: OCT image acquisition mode?)
Next, the main controller 211 determines whether or not the operation mode set in step S1 is the OCT image acquisition mode.

When it is determined that the operating mode set in step S1 is an OCT image (step S5: Y), the operation of the ophthalmic device 1 proceeds to step S6. On the other hand, when it is determined that the operating mode set in step S1 is not an OCT image acquisition mode (step S5: N), the operation of the ophthalmic device 1 proceeds to step S9.

(S6: Retract the shielding member)
When it is determined that the operating mode set in step S1 is an OCT image (step S5: Y), the main control unit 211 controls the shielding mechanism 130A to retract the shielding member 130 from the optical path of the reference light LR between the reference mirror 108 and the collimator lens unit 107.

(S7: Scan)
Next, the main control unit 211 controls the optical scanner 42 in accordance with the scanning conditions set in step S2 to scan the scanning range with the measurement light LS.

In step S7, the measurement light LS deflected by the optical scanner 42 is incident on the test eye E at each scan position on the test eye E. The return light of the measurement light LS returns to the optical image forming unit 100 from the incident position on the test eye E, and the interference light LC between the reference light LR that has passed through the reference optical path and the return light of the measurement light LS is dispersed by the diffraction grating 113. The light dispersed by the diffraction grating 113 is sequentially received by the image sensor 115.

(S8: OCT image formation process)
Next, the main controller 211 controls the OCT image forming part 221 to form a tomographic image as an OCT image based on the light reception result of the image sensor 115 acquired by the scan executed in step S7.

As described above, the OCT image forming unit 221 forms a tomographic image as an OCT image.

(S9: Place shielding member)
On the other hand, in step S5, when it is determined that the operating mode set in step S1 is not an OCT image (step S5: N), the main control unit 211 determines that the operating mode is an SLO image acquisition mode, and controls the shielding mechanism 130A to position the shielding member 130 from the optical path of the reference light LR between the reference mirror 108 and the collimator lens unit 107.

(S10: Scan)
Next, the main control unit 211 controls the optical scanner 42 in accordance with the scanning conditions set in step S2 to scan the scanning range with the measurement light LS.

In step S10, the measurement light LS deflected by the optical scanner 42 is incident on the test eye E at each scanning position on the test eye E. The return light of the measurement light LS returns to the optical image forming unit 100 from the incident position on the test eye E, and the return light of the measurement light LS is emitted from the fiber coupler 103 and dispersed by the diffraction grating 113. The light dispersed by the diffraction grating 113 is sequentially received by the image sensor 115.

(S11: SLO image formation process)
Next, the main control unit 211 controls the SLO image forming unit 222 to form a front image as an SLO image based on the light reception result of the image sensor 115 acquired by the scan executed in step S10.

Details of step S11 will be described later.

(S12: Display)
Following step S8 or step S11, the main control unit 211 causes the display unit 241 (or the display device 3) to display the tomographic image formed in step S8 or the front image (including a spectroscopic image or a hyperspectral image) formed in step S11.

In some embodiments, the main controller 211 causes the cross-sectional image and the front image to be displayed on the same screen of the display unit 241. In some embodiments, the main controller 211 causes the display unit 241 to display the cross-sectional image and the front image after aligning them so that positions corresponding to the same characteristic parts depicted in each image are associated with each other.

This completes the operation of the ophthalmic device 1 (end).

The process of step S11 is performed according to the flow shown in FIG. 11. In FIG. 11, a predetermined front image of one of the aspects shown in FIG. 5 to FIG. 9 is formed.

(S21: Obtain detection data)
In step S<b>11 , first, the SLO image forming unit 222 acquires detection data acquired by the image sensor 115 .

(S22: Binning process?)
When the binning process is performed on the detection data acquired in step S21 (step S22: Y), the operation of the SLO image forming unit 222 proceeds to step S23. On the other hand, when the binning process is not performed on the detection data acquired in step S21 (step S22: N), the operation of the SLO image forming unit 222 proceeds to step S24.

(S23: Binning process)
When performing the binning process on the detection data acquired in step S21 (step S22: Y), the SLO image forming unit 222 performs the binning process on a predetermined light receiving result among the detection data acquired in step S21. As a result, any one of the binning process results shown in FIG. 5 and FIG. 7 to FIG. 9 can be obtained.

(S24: Assign to pixel and save)
Next, the SLO image forming unit 222 assigns one of the detection data acquired in step S21 or pixel information corresponding to the binning processing result obtained in step S23 to a pixel in the image and stores it.

(S25: Next image?)
Next, the SLO image forming unit 222 determines whether or not to assign detection data or a binning processing result to a pixel of the next image.

When it is determined that detection data, etc., should be assigned to the pixels of the next image (step S25: Y), the operation of the SLO image forming unit 222 proceeds to step S24. This results in the formation of two or more spectroscopic images, such as a hyperspectral image.

On the other hand, when it is determined that detection data, etc. will not be assigned to the pixels of the next image (step S25: N), the operation of the SLO image forming unit 222 proceeds to step S26.

(S26: Next pixel?)
Next, the SLO image forming unit 222 determines whether to assign detection data or the binning process result to the next pixel in the image.

When it is determined that detection data, etc. should be assigned to the next pixel in the image (step S26: Y), the operation of the SLO image forming unit 222 proceeds to step S21.

On the other hand, when it is determined that detection data, etc. should not be assigned to the next pixel in the image (step S26: N), the processing of step S11 ends (END).

The ophthalmic device 1 can perform the scan of step S7 and the scan of step S10 in a time-division manner by repeatedly inserting and removing the shielding member 130.

As described above, in step S12, as shown in Fig. 12, the main controller 211 can cause the display unit 241 to display the tomographic image IMG1 formed by the OCT image forming unit 221 in step S8. Also, as shown in Fig. 13 or 14, the main controller 211 can cause the display unit 241 to display the front image IMG2 formed by the SLO image forming unit 222 in step S11, or a plurality of spectroscopic images IMG2 ₁ to IMG2 _N (N is an integer equal to or greater than 2) (or hyperspectral images).

As described above, according to the embodiment, by inserting and removing the shielding member 130 into and from the optical path of the reference light LR, it becomes possible to share at least a part of the interference optical system between the OCT optical system and the SLO optical system. Therefore, it is possible to provide an ophthalmic device 1 as an optical image forming device for acquiring a tomographic image and a front image while minimizing the increase in size of the device.

The diffraction grating 113 may be a reflective diffraction grating such as a grating mirror, a prism, or an acousto-optical element.

[Action]
An optical image forming apparatus, a control method for the optical image forming apparatus, and a program according to an embodiment will be described.

A first aspect of some embodiments is an optical image forming device (ophthalmic device 1) including an interference optical system (optical system included in the optical image forming unit 100 and the optical scanner 42) including an optical scanner (42), a shielding member (130), a spectroscopic member (diffraction grating 113), an image sensor (image sensor 115), a tomographic image forming section (OCT image forming section 221), and a front image forming section (SLO image forming section 222). The interference optical system splits low-coherence light (L0) from a light source (light source unit 101) into measurement light (LS) and reference light (LR), irradiates the measurement light deflected by the optical scanner onto the object to be measured (test eye E), and causes interference between the reference light passing through the reference optical path and the return light of the measurement light from the object to be measured. The shielding member is insertable and detachable from the reference optical path. The spectroscopic member separates the interference light between the reference light and the return light generated by the interference optical system when the shielding member is retracted from the reference optical path, or separates the return light output from the interference optical system when the shielding member is disposed in the reference optical path. The image sensor receives the light separated by the spectroscopic member. The tomographic image forming unit forms a tomographic image (OCT image) of the object to be measured based on the light reception result of the light obtained by the image sensor from the separated interference light. The front image forming unit forms a front image (SLO image) of the object to be measured based on the light reception result of the light obtained by the image sensor from the separated return light.

According to this aspect, by inserting and removing the shielding member with respect to the reference light path, at least a part of the interference optical system can be shared between the optical system for acquiring a tomographic image and the optical system for acquiring a front image. Therefore, it is possible to provide an optical image forming device for acquiring a tomographic image and a front image while minimizing the increase in size of the device.

In a second aspect of some embodiments, in the first aspect, the dispersing element is a diffraction grating (113). The image sensor is a line sensor in which two or more light receiving elements are arranged in a direction corresponding to the arrangement direction of the grating pattern formed on the diffraction grating.

According to this aspect, it is possible to provide an optical imaging device that uses a spectrometer including a diffraction grating and a line sensor to obtain a tomographic image and a front image while minimizing the increase in size of the device.

In a third aspect of some embodiments, in the second aspect, the tomographic image forming unit forms a tomographic image based on two or more light receiving results from two or more light receiving elements, and the front image forming unit forms two or more front images in which pixel information corresponding to each of the two or more light receiving results is assigned to each pixel of each front image.

According to this aspect, it is possible to provide an optical imaging device for acquiring a tomographic image and two or more front images as hyperspectral images while minimizing the increase in size of the device.

In a fourth aspect of some embodiments, in the second aspect, the tomographic image forming unit forms a tomographic image based on two or more light receiving results from two or more light receiving elements, and the front image forming unit forms two or more front images by assigning pixel information corresponding to the binning process results for the multiple light receiving results from the two or more light receiving elements to each pixel of each front image.

According to this aspect, by performing binning processing, it is possible to provide an optical image forming device that can obtain a tomographic image and two or more front images as spectroscopic images while minimizing the increase in size of the device.

In a fifth aspect of some embodiments, in the fourth aspect, the front image forming unit forms a single front image by assigning pixel information corresponding to the binning process result for all light receiving results from two or more light receiving elements to each pixel.

According to this aspect, by performing binning processing on all light receiving results from two or more light receiving elements, it is possible to provide an optical imaging device for acquiring a tomographic image and a single front image while minimizing the increase in size of the device.

In a sixth aspect of some embodiments, in the fourth aspect, the front image forming unit divides two or more light receiving elements into a plurality of light receiving element groups, performs a binning process on the light receiving results of the light receiving elements for each of the plurality of light receiving element groups, and assigns pixel information corresponding to the binning process result to each pixel, thereby forming two or more front images as two or more spectral images.

According to this aspect, it is possible to provide an optical imaging device that can obtain a tomographic image and two or more front images as spectroscopic images in a desired wavelength range while minimizing the increase in size of the device.

A seventh aspect of some embodiments is a method for controlling an optical image forming device (ophthalmic device 1) including an interference optical system (optical system included in the optical image forming unit 100 and the optical scanner 42) including an optical scanner (42), a shielding member (130), a spectroscopic member (diffraction grating 113), and an image sensor (image sensor 115). The method for controlling the optical image forming device includes a first interference optical system control step, a tomographic image generating step, a second interference optical system control step, and a front image forming step. The first interference optical system control step causes the interference optical system to generate interference light by retracting the shielding member from the reference optical path. The tomographic image forming step forms a tomographic image of the object to be measured based on the light reception result obtained by receiving light obtained by dispersing the interference light by the image sensor. The second interference optical system control step causes the interference optical system to output return light by inserting a shielding member into the reference optical path. The front image forming step forms a front image of the object to be measured based on the light reception result obtained by receiving light obtained by dispersing the return light by the image sensor.

According to this method, by inserting and removing the shielding member with respect to the reference light path, it becomes possible to share at least a part of the interference optical system between the optical system for acquiring a tomographic image and the optical system for acquiring a front image. Therefore, it becomes possible to acquire a tomographic image and a front image while minimizing the increase in size of the device.

In an eighth aspect of some embodiments, in the seventh aspect, the dispersing element is a diffraction grating (113). The image sensor is a line sensor in which two or more light receiving elements are arranged in a direction corresponding to the arrangement direction of the grating pattern formed on the diffraction grating.

This method makes it possible to obtain cross-sectional images and frontal images using a spectrometer that includes a diffraction grating and a line sensor while minimizing the increase in size of the device.

In a ninth aspect of some embodiments, in the eighth aspect, the tomographic image forming step forms a tomographic image based on two or more light receiving results from two or more light receiving elements, and the front image forming step forms two or more front images in which pixel information corresponding to each of the two or more light receiving results is assigned to each pixel of each front image.

This method makes it possible to obtain a cross-sectional image and two or more front images as hyperspectral images while minimizing the increase in size of the device.

In a tenth aspect of some embodiments, in the eighth aspect, the tomographic image forming step forms a tomographic image based on two or more light receiving results from two or more light receiving elements, and the front image forming step forms two or more front images by assigning pixel information corresponding to the binning process results for the multiple light receiving results from the two or more light receiving elements to each pixel of each front image.

According to this method, by performing binning processing, it is possible to obtain a cross-sectional image and two or more front images as spectroscopic images while minimizing the increase in size of the device.

In an eleventh aspect of some embodiments, in the tenth aspect, the front image forming step forms a single front image by assigning pixel information corresponding to the binning process result for all light receiving results in two or more light receiving elements to each pixel.

According to this method, by performing a binning process on all light receiving results from two or more light receiving elements, it is possible to obtain a tomographic image and a single front image while minimizing the increase in size of the device.

In a twelfth aspect of some embodiments, in the ninth aspect, the front image forming step divides two or more light receiving elements into a plurality of light receiving element groups, performs a binning process on the light receiving results of the light receiving elements for each of the plurality of light receiving element groups, and assigns pixel information corresponding to the binning process result to each pixel to form two or more front images as two or more spectral images.

This method makes it possible to obtain a tomographic image and two or more front images as spectroscopic images in the desired wavelength range while minimizing the increase in size of the device.

A thirteenth aspect of some embodiments is a program for causing a computer to execute each step of the method for controlling an optical imaging device described in any one of the seventh to twelfth aspects.

According to such a program, by inserting and removing a shielding member with respect to the reference light path, it becomes possible to share at least a part of the interference optical system between the optical system for acquiring a tomographic image and the optical system for acquiring a front image. Therefore, it is possible to provide an optical image forming device for acquiring a tomographic image and a front image while minimizing the increase in size of the device.

＜Other＞
The embodiment described above is merely one example for carrying out the present invention. Anyone who wishes to carry out the present invention may make any modifications, omissions, additions, etc. within the scope of the gist of the present invention.

Reference Signs List 1 Ophthalmic apparatus 42 Optical scanner 100 Optical image forming unit 101 Light source unit 113 Diffraction grating 115 Image sensor 130 Shielding member 210 Control unit 211 Main control unit 220 Image forming unit 221 OCT image forming unit 222 SLO image forming unit E Subject eye LR Reference light LS Measurement light LC Interference light

Claims (13)

an interference optical system including an optical scanner, which splits low-coherence light from a light source into measurement light and reference light, irradiates the measurement light deflected by the optical scanner onto an object to be measured, and causes interference between the reference light passing through a reference optical path and return light of the measurement light from the object to be measured;
a shielding member that is insertable into and detachable from the reference light path;
a spectroscopic member that spectroscopically separates interference light between the reference light and the return light generated by the interference optical system in a state in which the shielding member is retracted from the reference light path, or that spectroscopically separates the return light output from the interference optical system in a state in which the shielding member is disposed in the reference light path;
an image sensor that receives the light dispersed by the dispersing member;
a tomographic image forming unit that forms a tomographic image of the object to be measured based on a light receiving result of the light obtained by the image sensor and separated from the interference light;
a front image forming unit that forms a front image of the object to be measured based on a light receiving result of the light obtained by the image sensor and splitting the return light;
1. An optical imaging device comprising: the spectroscopic member is a diffraction grating,
2. The optical imaging device according to claim 1, wherein the image sensor is a line sensor in which two or more light receiving elements are arranged in a direction corresponding to an arrangement direction of a grating pattern formed on the diffraction grating. the tomographic image forming unit forms the tomographic image based on two or more light receiving results in the two or more light receiving elements;
The optical image forming device according to claim 2 , wherein the front image forming unit forms two or more of the front images, each of which is assigned pixel information corresponding to each of the two or more light receiving results for each pixel of the front image. the tomographic image forming unit forms the tomographic image based on two or more light receiving results in the two or more light receiving elements;
The optical image forming device according to claim 2, characterized in that the front image forming unit forms two or more of the front images by assigning pixel information corresponding to a binning processing result for a plurality of light receiving results at the two or more light receiving elements to each pixel of each front image. The optical image forming device according to claim 4 , wherein the front image forming section forms the single front image by assigning pixel information corresponding to a binning process result for all light receiving results in the two or more light receiving elements to each pixel. The optical image forming device according to claim 4, characterized in that the front image forming unit divides the two or more light receiving elements into a plurality of light receiving element groups, performs a binning process on the light receiving results of the light receiving elements for each of the plurality of light receiving element groups, and forms two or more of the front images as two or more spectral images by assigning pixel information corresponding to the binning process result to each pixel. an interference optical system including an optical scanner, which splits low-coherence light from a light source into measurement light and reference light, irradiates the measurement light deflected by the optical scanner onto an object to be measured, and causes interference between the reference light passing through a reference optical path and return light of the measurement light from the object to be measured;
a shielding member that is insertable into and detachable from the reference light path;
a spectroscopic member that spectroscopically separates the interference light between the return light and the reference light generated by the interference optical system, or the return light output from the interference optical system;
an image sensor that receives the light dispersed by the dispersing member;
A method for controlling an optical imaging device, comprising:
a first interference optical system control step of causing the interference optical system to generate the interference light by retracting the shielding member from the reference light path;
a tomographic image forming step of forming a tomographic image of the object to be measured based on a light receiving result obtained by receiving light obtained by dispersing the interference light by the image sensor;
a second interference optical system control step of outputting the return light from the interference optical system by inserting the blocking member into the reference light path;
a front image forming step of forming a front image of the object to be measured based on a light reception result obtained by receiving light obtained by dispersing the return light by the image sensor;
A method for controlling an optical imaging device, comprising: the spectroscopic member is a diffraction grating,
8. The method for controlling an optical imaging device according to claim 7, wherein the image sensor is a line sensor in which two or more light receiving elements are arranged in a direction corresponding to an arrangement direction of a grating pattern formed on the diffraction grating. The tomographic image forming step forms the tomographic image based on two or more light receiving results in the two or more light receiving elements,
The control method for an optical image forming device according to claim 8, characterized in that the front image forming step forms two or more of the front images, each of which is assigned pixel information corresponding to each of the two or more light receiving results for each pixel of the front image. The tomographic image forming step forms the tomographic image based on two or more light receiving results in the two or more light receiving elements,
The control method for an optical image forming device according to claim 8, characterized in that the front image forming step forms two or more of the front images by assigning pixel information corresponding to a binning processing result for a plurality of light receiving results in the two or more light receiving elements to each pixel of each front image. The control method for an optical image forming device according to claim 10, characterized in that the front image forming step forms the single front image by assigning pixel information corresponding to a binning processing result for all light receiving results in the two or more light receiving elements to each pixel. 10. The method for controlling an optical image forming device according to claim 9, characterized in that the front image forming step divides the two or more light receiving elements into a plurality of light receiving element groups, performs a binning process on the light receiving results of the light receiving elements for each of the plurality of light receiving element groups, and assigns pixel information corresponding to the binning process result to each pixel, thereby forming the two or more front images as two or more spectral images. A program that causes a computer to execute each step of the method for controlling an optical image forming device according to any one of claims 7 to 12.

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