Image processing method, image processing device, ophthalmic device, and program

Abstract

This image processing device emits light from a light source onto an examined eye through an optical system of a first numerical aperture, and acquires information indicating interference light obtained by detecting interference light between signal light, in which light returning from the examined eye owing to the light emitted thereon is transmitted through an optical system of a second numerical aperture, and reference light, which is a division of light from the light source (S200). A first process (S202) is performed for projecting information indicating the interference light to a four-dimensional frequency aperture that is on a four-dimensional space of the light source frequency and the frequency of light from the examined eye owing to the signal light, and is formed by the optical system of the first numerical aperture and the optical system of the second numerical aperture. A second process (S204) is performed for projecting the projected information to a three-dimensional space.

Description

[Technical Field]

[0001] The technology of the present disclosure relates to an image processing method, an ophthalmic apparatus, and a program. [Background technology]

[0002] An optical coherence tomography (OCT) is capable of measuring the structure of a subject's eye using light reflected from different layers in the fundus of the subject's eye, and can obtain one-dimensional depth images, two-dimensional tomographic images, and three-dimensional images. For example, a technique for generating data on the structure of a subject's eye using an OCT is known (U.S. Pat. No. 10,238,281). Summary of the Invention

[0003] The first aspect of the technology of the present disclosure is An image processing method in an image processing device performed by a processor, irradiating the light from the light source onto the illuminated object by an optical system with a first numerical aperture, and detecting interference light between signal light, which is returned from the illuminated object by the irradiated light and propagated by an optical system with a second numerical aperture, and reference light, which is obtained by dividing the light from the light source, and acquiring information indicating the interference light; a first process of projecting information representing the interference light onto a four-dimensional frequency aperture formed by an optical system with the first numerical aperture and an optical system with the second numerical aperture in a four-dimensional space of the frequency of the light source and the three-dimensional light frequency representing the illuminated object; and a second process of projecting the projected information onto the three-dimensional space. The image processing method includes:

[0004] A second aspect of the technology of the present disclosure is In an image processing device having a memory and a processor, The processor: irradiating the light from the light source onto the illuminated object by an optical system with a first numerical aperture, and detecting interference light between signal light, which is returned from the illuminated object by the irradiated light and propagated by an optical system with a second numerical aperture, and reference light, which is obtained by dividing the light from the light source, and acquiring information indicating the interference light; a first process of projecting information representing the interference light onto a four-dimensional frequency aperture formed by an optical system with the first numerical aperture and an optical system with the second numerical aperture in a four-dimensional space of the frequency of the light source and the three-dimensional light frequency representing the illuminated object; and a second process of projecting the projected information onto the three-dimensional space. The image processing device performs the above.

[0005] A third aspect of the technology of the present disclosure is On the computer, light from a light source is irradiated onto the subject's eye by an optical system with a first numerical aperture, and return light from the subject's eye due to the irradiated light is propagated through an optical system with a second numerical aperture, and interference light between signal light and reference light obtained by dividing the light from the light source is detected, and information indicating the interference light obtained is acquired; a first process of projecting information indicating the interference light onto a four-dimensional frequency aperture formed by an optical system with the first numerical aperture and an optical system with the second numerical aperture in a four-dimensional space of a frequency of the light source and a frequency of light from the eye to be examined by the signal light; and A second process is performed. It is a program that executes processing. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic configuration diagram of an ophthalmologic system according to an embodiment. [Figure 2] 1 is a schematic configuration diagram of an ophthalmologic apparatus according to an embodiment. [Figure 3] 1 is a conceptual diagram of an OCT image. [Figure 4] FIG. 1 is a conceptual diagram of an example showing information about an OCT image in an OCT system in a four-dimensional frequency space. [Figure 5] FIG. 10 is a conceptual diagram showing an example of a four-dimensional aperture A4. [Figure 6] FIG. 10 is a conceptual diagram showing a part of a four-dimensional aperture A4. [Figure 7] FIG. 1 is an explanatory diagram showing the concept of correction processing of an OCT image by the double projection method. [Figure 8] FIG. 1 is a conceptual diagram of the optical system in an OCT system. [Figure 9] FIG. 2 is an explanatory diagram of functions realized by an image processing program. [Figure 10] 10 is a flowchart illustrating an example of the flow of image processing. [Figure 11A] FIG. 2 is a conceptual diagram showing an example of an OCT image according to the present embodiment. [Figure 11B] FIG. 10 is a conceptual diagram showing a comparative example of an OCT image. DETAILED DESCRIPTION OF THE INVENTION

[0007] An ophthalmologic system 100 according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an ophthalmologic system 100. As shown in FIG. 1, the ophthalmologic system 100 includes an ophthalmologic apparatus 110, a server apparatus (hereinafter referred to as "server") 140, and a display device (hereinafter referred to as "viewer") 150. The ophthalmologic apparatus 110 acquires fundus images. The server 140 stores, in association with patient IDs, a plurality of fundus images obtained by photographing the funduses of a plurality of patients using the ophthalmologic apparatus 110 and axial lengths measured by an axial length measuring device (not shown). The viewer 150 displays the fundus images and analysis results acquired by the server 140. In this embodiment, a case will be described in which an eye to be examined is applied as an example of an "irradiated object" of the technology of the present disclosure. The ophthalmic apparatus 110 is an example of an "ophthalmic apparatus" of the technology of the present disclosure. The ophthalmic apparatus is also an example of an "image processing apparatus" of the technology of the present disclosure.

[0008] The ophthalmologic apparatus 110, the server 140, and the viewer 150 are connected to each other via a network 130. The network 130 may be any network such as a LAN, a WAN, the Internet, or a wide area Ethernet network. For example, when the ophthalmologic system 100 is established in a medical facility such as a hospital, a LAN may be used as the network 130.

[0009] The viewer 150 is a client in a client-server system, and a plurality of viewers 150 are connected via a network. A plurality of servers 140 may also be connected via a network to ensure system redundancy. If the ophthalmic apparatus 110 has an image processing function and an image viewing function of the viewer 150, the ophthalmic apparatus 110 can acquire, process, and view fundus images in a standalone state. If the server 140 has an image viewing function of the viewer 150, the configuration of the ophthalmic apparatus 110 and the server 140 can acquire, process, and view fundus images.

[0010] In addition, other ophthalmic devices (examination equipment for visual field measurement, intraocular pressure measurement, etc.) and diagnostic support devices that perform image analysis using AI (Artificial Intelligence) may be connected to the ophthalmic device 110, the server 140, and the viewer 150 via the network 130.

[0011] Next, the configuration of the ophthalmologic apparatus 110 will be described with reference to FIG.

[0012] For ease of explanation, Scanning Laser Ophthalmoscope will be referred to as "SLO" and Optical Coherence Tomography will be referred to as "OCT."

[0013] When the ophthalmologic apparatus 110 is placed on a horizontal plane, the horizontal direction is defined as the "X direction," the vertical direction relative to the horizontal plane is defined as the "Y direction," and the direction connecting the center of the pupil of the anterior segment of the subject's eye 12 and the center of the eyeball is defined as the "Z direction." Therefore, the X direction, Y direction, and Z direction are perpendicular to each other.

[0014] The ophthalmologic apparatus 110 includes an imaging device 14 and a control device 16. The imaging device 14 is equipped with an SLO unit 18 and an OCT unit 20, and acquires a fundus image of the subject's eye 12. Hereinafter, a two-dimensional fundus image acquired by the SLO unit 18 will be referred to as an SLO image. Furthermore, a tomographic image or a front image (en-face image) of the retina created based on OCT data acquired by the OCT unit 20 may also be referred to as an OCT image.

[0015] The control device 16 comprises a computer having a CPU (Central Processing Unit) 16A, a RAM (Random Access Memory) 16B, a ROM (Read-Only Memory) 16C, and an input / output port (I / O) 16D.

[0016] The control device 16 includes an input / display device 16E connected to the CPU 16A via an I / O port 16D. The input / display device 16E has a graphic user interface that displays an image of the subject's eye 12 and receives various instructions from the user. An example of the graphic user interface is a touch panel display.

[0017] The control device 16 also includes an image processor 17 connected to an I / O port 16D. The image processor 17 generates an image of the subject's eye 12 based on data obtained by the photographing device 14. The control device 16 is connected to a network 130 via a communication interface 16F. The image processor 17 also includes a memory 17M, which is a nonvolatile storage device capable of storing an image processing program, which will be described later.

[0018] 2, the control device 16 of the ophthalmic apparatus 110 includes the input / display device 16E, but the technology of the present disclosure is not limited to this. For example, the control device 16 of the ophthalmic apparatus 110 may not include the input / display device 16E, but may include an input / display device that is physically independent from the ophthalmic apparatus 110. In this case, the display device may include an image processing processor unit, and the image processing processor unit may display an SLO image or the like based on an image signal output from the ophthalmic apparatus 110.

[0019] The image capturing device 14 operates under the control of the CPU 16A of the control device 16. The image capturing device 14 includes an SLO unit 18, an image capturing optical system 19, and an OCT unit 20. The image capturing optical system 19 includes an optical scanner 22 and a wide-angle optical system 30.

[0020] The optical scanner 22 performs two-dimensional scanning in the X and Y directions with the light emitted from the SLO unit 18. The optical scanner 22 may be any optical element that can deflect a light beam, such as a polygon mirror or a galvanometer mirror, or a combination thereof.

[0021] The wide-angle optical system 30 combines the light from the SLO unit 18 and the light from the OCT unit 20 .

[0022] The wide-angle optical system 30 may be a reflective optical system using a concave mirror such as an elliptical mirror, a refractive optical system using a wide-angle lens, or a catadioptric system combining concave mirrors and lenses. By using a wide-angle optical system using an elliptical mirror or a wide-angle lens, it becomes possible to photograph the retina in the peripheral part of the fundus as well as the center of the fundus.

[0023] When a system including an elliptical mirror is used, the system using the elliptical mirror described in International Publication WO2016 / 103484 or International Publication WO2016 / 103489 may be used. The disclosures of International Publication WO2016 / 103484 and International Publication WO2016 / 103489 are each incorporated herein by reference in their entirety.

[0024] The wide-angle optical system 30 enables observation of a wide field of view (FOV) region 12A of the fundus. The FOV region 12A indicates the range that can be photographed by the imaging device 14. The FOV region 12A can be expressed as a field of view. In this embodiment, the field of view can be defined by an internal illumination angle and an external illumination angle. The external illumination angle is the illumination angle of the light beam irradiated from the ophthalmic device 110 to the subject's eye 12, determined with the pupil 27 as the reference. The internal illumination angle is the illumination angle of the light beam irradiated to the fundus F, determined with the eyeball center O as the reference. The external illumination angle and the internal illumination angle correspond to each other. For example, if the external illumination angle is 120 degrees, the internal illumination angle corresponds to approximately 160 degrees. In this embodiment, the internal illumination angle is 200 degrees.

[0025] Here, an SLO fundus image captured at an internal illumination angle of 160 degrees or more is referred to as a UWF-SLO fundus image. UWF stands for Ultra Wide Field. The wide-angle optical system 30, which provides an ultra-wide field of view (FOV) of the fundus, can capture an image of the fundus of the subject's eye 12 from the posterior pole to the equator.

[0026] The ophthalmologic apparatus 110 can capture an image of an area 12A with an internal illumination angle of 200°, with the center O of the eyeball of the subject's eye 12 as the reference position. The internal illumination angle of 200° corresponds to an external illumination angle of 110° with the pupil of the subject's eye 12 as the reference. In other words, the wide-angle optical system 30 irradiates laser light from the pupil at an angle of view of an external illumination angle of 110°, and captures an image of a fundus area of ​​200° with an internal illumination angle.

[0027] The SLO system is realized by a control device 16, an SLO unit 18, and an imaging optical system 19 shown in Fig. 2. The SLO system includes a wide-angle optical system 30, which enables fundus imaging in a wide FOV area 12A.

[0028] The SLO unit 18 includes a light source 40 including a light source for B light (blue light), a light source for G light (green light), a light source for R light (red light), and a light source for IR light (infrared light (e.g., near-infrared light)). The light of each color from the light source 40 is guided along the same optical path.

[0029] The SLO unit 18 is configured to be switchable between a light source that emits laser light of different wavelengths, or a combination of light sources that emit light, such as a mode that emits R light and G light and a mode that emits infrared light. Note that the technology disclosed herein is not limited to having four light sources: a light source for B light, a light source for G light, a light source for R light, and a light source for IR light. For example, the SLO unit 18 may further include a light source for white light, and may emit light in various modes, such as a mode that emits G light, R light, and B light, or a mode that emits only white light.

[0030] The light incident on the photographing optical system 19 from the SLO unit 18 is scanned in the X and Y directions by the optical scanner 22. The scanning light passes through the wide-angle optical system 30 and the pupil 27 and is irradiated onto the fundus. The light reflected by the fundus is then scanned by the wide-angle optical system 30 and the optical scanner 22. The beam is then injected into the SLO unit 18 via 22.

[0031] The SLO unit 18 includes a beam splitter 60 that guides light from the posterior segment (fundus) of the subject's eye 12 to a detecting element 70. The detecting element 70 detects the light from the posterior segment (fundus) of the subject's eye 12. Note that a beam splitter 60 and a detecting element 70 may be provided for each color. For example, beam splitters for B light, G light, R light, and IR light are arranged on the optical axis, and detecting elements of the corresponding colors are arranged downstream of each beam splitter. The beam splitter for B light may reflect B light and transmit light other than B light. Similarly, the beam splitter for G light may reflect G light and transmit light other than G light, the beam splitter for R light may reflect R light and transmit light other than R light, and the beam splitter for IR light may reflect IR light.

[0032] The image processor 17, which operates under the control of the CPU 16A, generates a UWF-SLO image using the light (reflected light reflected by the fundus) incident on the SLO unit 18 via the wide-angle optical system 30 and the optical scanner 22, i.e., the signal from the detection element 70 for each color of light.

[0033] The control device 16 also controls the light sources 40 for each color to emit light simultaneously. By simultaneously photographing the fundus of the subject's eye 12 with B light, G light, and R light, a G-color fundus image, an R-color fundus image, and a B-color fundus image, each of which corresponds to each other, are obtained. An RGB color fundus image is obtained from the G-color fundus image, the R-color fundus image, and the B-color fundus image. The control device 16 controls the light sources 40 for each color to emit light simultaneously, and by simultaneously photographing the fundus of the subject's eye 12 with G light and R light, a G-color fundus image and an R-color fundus image, each of which corresponds to each other, are obtained. An RG color fundus image is obtained from the G-color fundus image and the R-color fundus image.

[0034] The wide-angle optical system 30 makes the field of view (FOV) of the fundus an ultra-wide angle, and can capture an image of the area from the posterior pole of the fundus of the subject's eye 12 beyond the equator.

[0035] The OCT system is realized by the control device 16, OCT unit 20, and imaging optical system 19 shown in FIG. 2. The OCT system includes a wide-angle optical system 30, which enables OCT imaging of the peripheral part of the fundus, similar to the above-described SLO fundus image capture. In other words, the wide-angle optical system 30, which provides an ultra-wide field of view (FOV) of the fundus, enables OCT imaging of the area from the posterior pole of the fundus beyond the equator of the subject's eye 12. OCT data of the peripheral part of the fundus can be acquired, and a tomographic image and the 3D structure of the fundus can be obtained by image processing the OCT data.

[0036] The OCT unit 20 includes a light source 20A, a sensor (detection element) 20B, a first optical coupler 20C, a reference optical system 20D, and an illumination / detection optical system 20E including a second optical coupler 200 (FIG. 3).

[0037] Light emitted from the light source 20A is split by the first optical coupler 20C. One of the split lights is incident on the imaging optical system 19 as measurement light via the illumination and detection optical system 20E. The measurement light is irradiated onto the fundus via the wide-angle optical system 30 and the pupil 27. The measurement light reflected by the fundus is incident on the OCT unit 20 via the wide-angle optical system 30 and the optical scanner 22, and then incident on the sensor 20B via the illumination and detection optical system 20E and the first optical coupler 20C. The other light split by the first optical coupler 20C is incident on the reference optical system 20D, and its return light is incident on the sensor 20B via the first optical coupler 20C as reference light.

[0038] The light incident on the sensor 20B, that is, the measurement light reflected from the fundus, and the reference light are mutually exclusive. The optical fiber 10B is interfering with the light beam, generating interference light. The interference light is received by the sensor 20B. The image processor 17, which operates under the control of the CPU 16, generates OCT data detected by the sensor 20B. Based on the OCT data, a tomographic image and an OCT image can be generated.

[0039] The OCT unit 20 described above can scan a predetermined range (for example, a rectangular range of 6 mm x 6 mm) in one OCT scan. The predetermined range is not limited to 6 mm x 6 mm, and can be a square range of 12 mm x 12 mm or 23 mm x 23 mm, or a rectangular range such as 14 mm x 9 mm or 6 mm x 3.5 mm, or any other rectangular range. It can also be a circular range with a diameter of 6 mm, 12 mm, or 23 mm.

[0040] By using the wide-angle optical system 30, the ophthalmic apparatus 110 can scan an area 12A with an internal illumination angle of 200°. That is, by controlling the optical scanner 22, OCT imaging of a predetermined range is performed. The ophthalmic apparatus 110 can generate OCT data through the OCT imaging. Therefore, the ophthalmic apparatus 110 can generate OCT images, such as a tomographic image (B-scan image) of the fundus, OCT volume data, and an en-face image (a front image generated from the OCT volume data) that is a cross section of the OCT volume data.

[0041] The OCT data (or image data of the OCT image) is sent from the ophthalmologic apparatus 110 to the server 140 via the communication interface 16F and stored in a storage device.

[0042] Incidentally, OCT systems can simultaneously acquire depth information at the fundus. Figure 3 shows an example of an image (OCT image) of dots aligned on an optical axis simultaneously acquired by an OCT system using optical systems (e.g., objective lenses) with different numerical apertures (NA). Figure 3 also shows examples of dot images aligned on the optical axis for optical systems with NA = 0.1, NA = 0.3, and NA = 0.5. In the figure, the depth axis at the same position on the x-axis is designated as cτ. Note that c indicates the luminous flux, and in the figure, cτ = τ. Hereinafter, the unit system of c = 1 is used. The depth of focus of the optical system is designated as DOF. As shown in the example in Figure 3, the image of the dots acquired by the OCT system becomes incomplete as the depth position at the fundus moves away from the focal position (e.g., the depth of focus) of the optical system. That is, as the position where fundus information is acquired moves away from the focal position (e.g., the focal depth) of the imaging optical system 19, the resolution gradually decreases. Therefore, as the distance from the focal depth increases, the image gradually becomes an incomplete dot image with blurring and distortion. Fundus information outside the focal depth, which is a predetermined distance (e.g., about 10 times) away, is partially lost, and it is difficult to completely restore the lost information using commonly used image processing. While there are techniques for correcting blurring and distortion in images outside the focal depth using processes called deconvolution and refocusing, the correction is incomplete because some information is lost when the information is acquired.

[0043] The reason why the restoration of the OCT image by the OCT system is incomplete is thought to be that the information acquired by the OCT system does not reflect all of the information about the fundus of the subject's eye 12, and is therefore incomplete.

[0044] FIG. 4 shows an example of information about an OCT image. FIG. 4 is an example showing, in a four-dimensional frequency space, information about an OCT image formed by an optical system of an OCT system using an optical system (for example, an objective lens) with NA=0.9. In the figure, ν indicates the frequency of light from the light source 20A (in this embodiment, the frequency of light irradiated onto the fundus), and fx, fy, and fz indicate the object frequencies (in this embodiment, the frequencies of light reflected from the fundus). The frequency ν may also be applied to the angular frequency ω (ω=2πν). Note that, for simplicity of explanation, the axis of the object frequency fy is omitted. Also, FIG. 4 shows an example of information about an OCT image formed by an optical system (for example, an objective lens) in an OCT system using the same optical path, i.e., Specifically, the optical path of the irradiated measuring light and the optical path of the reflected light from the eye 12 are the same, and both have NA=0.9.

[0045] Here, the object frequencies (fx, fy, fz) are uniform in the v direction. Furthermore, in four-dimensional frequency space, because the frequencies in real space are within a predetermined range, a window function representing a four-dimensional aperture A4 (4-D aperture) is defined as the device function of the OCT system. The four-dimensional aperture A4 is an aperture space in four-dimensional frequency space. Therefore, the OCT system acquires only the frequencies within the four-dimensional aperture A4 among the object frequencies. However, the frequencies within the four-dimensional aperture A4 (four-dimensional information) are not acquired in their entirety; rather, they are integrated in the fz direction during detection and acquired as three-dimensional information. In this way, when the frequencies within the four-dimensional aperture A4 are integrated in the fz direction, part of the four-dimensional information is lost.

[0046] Therefore, in this embodiment, an OCT system is provided that can reduce information loss, which is the loss of part of four-dimensional information.

[0047] For example, in a system such as an interference microscope that enables three-dimensional scanning, the image frequency is the ν integral of the object frequency within the four-dimensional aperture A4. Therefore, by applying the ν integral of the object frequency within the four-dimensional aperture A4, it is possible to reduce information loss, in which part of the four-dimensional information is lost.

[0048] In this embodiment, the OCT system that reduces information loss includes an optical system that sufficiently thins the four-dimensional aperture A4. This reduces information loss, which is the loss of part of the four-dimensional information even when performing fz integration. Specifically, the optical system is configured so that the NA of the illumination-side optical system that illuminates the subject's eye 12 and the NA of the detection-side optical system that detects light from the subject's eye 12 (e.g., reflected light from the fundus) are different. For example, by making the NA of the illumination-side optical system for the subject's eye 12 sufficiently small, e.g., approximately zero, it becomes possible to form a thin four-dimensional aperture A4 even if the NA of the detection-side optical system for light from the subject's eye 12 is larger than the NA of the illumination-side optical system. In this embodiment, an optical system with a sufficiently small NA is referred to as having an "NA of zero (NA=0)." In other words, an optical system with an NA of zero includes an optical system with an NA greater than zero, resulting in an aperture angle smaller than the image height formed by the light beam. An optical system with an NA of zero also includes an optical system that is configured to collimate incident or emitted light, and can be considered to have an NA of zero.

[0049] In addition, an optical system with a zero NA can be applied to the optical system of an OCT system that uses full-field illumination, which uniformly illuminates an object on the irradiated side, such as the subject's eye 12, or illuminates a specified area of ​​the object on the irradiated side all at once.

[0050] Even if the four-dimensional aperture A4 is formed thin, the object frequency within the four-dimensional aperture A4 has a sufficient amount of information (including fz information), and it is possible to reduce information loss, in which part of the information (four-dimensional information) about the subject's eye 12 is lost even when fz integration is performed.

[0051] That is, in this embodiment, an optical system is formed with respect to the eye 12 to have different NAs for the illumination-side optical system and the detection-side optical system. Specifically, an optical system is formed in which the illumination-side optical system has a sufficiently small NA, i.e., zero, and the detection-side optical system has a larger NA than the illumination-side optical system. This makes it possible to form a thin four-dimensional aperture A4, as shown in FIG. 5. More specifically, as shown in FIG. 6 by the four-dimensional aperture A4 at a predetermined frequency (frequency ν of light from the light source 20A), the shape having information in the fz direction (a crescent shape in the figure) changes to a linear shape. A series of these linear apertures constitutes the four-dimensional aperture A4 (FIG. 5) in this embodiment.

[0052] The optical system for forming a thin four-dimensional aperture A4 is an optical system in which one optical system has an NA of zero or close to zero, and the other optical system has an NA larger than the NA of the other optical system. For example, an example of a sufficiently small NA in an optical system such as a microscope includes NA=0.2. Therefore, in this embodiment, from the viewpoint of forming a thin four-dimensional aperture A4, it is preferable that the NA of the illumination-side optical system on the excitation side has the following relationship as a condition for a small NA: 0≦NA≦0.2

[0053] The thin four-dimensional aperture A4 is an example of the "four-dimensional frequency aperture" of the technology of the present disclosure.

[0054] Note that, hereinafter, as an example, a case will be described in which the optical system on the side where light is irradiated onto the subject's eye 12 has an NA of zero, and the optical system on the side where light from the subject's eye 12 is detected has an NA of a finite value; however, the technology of the present disclosure is not limited to this. For example, the optical system on the detection side may have an NA of zero, and the optical system on the irradiation side may have an NA of a finite value. Furthermore, the optical system with an NA of zero may have an NA of a finite value. That is, the NA of the optical system on the irradiation side and the NA of the optical system on the detection side may be formed to be different. By making the NAs of the two optical systems different, it is possible to make the four-dimensional aperture A4 thinner than when both optical systems have the same NA.

[0055] In this embodiment, the OCT image is corrected using a four-dimensional aperture A4, which can reduce information loss. Specifically, the OCT image is corrected using a two-stage processing method (double projection method) using frequency information of the OCT image. As shown in FIG. 7 , the OCT image correction process is conceptually illustrated. In the first stage, frequency information (I) of the OCT image G1 is projected onto the thin four-dimensional aperture A4. In the second stage, information (~I) of the image G2 projected onto the four-dimensional aperture A4 is further projected in the ν (=2π / ω) direction, i.e., onto the (fx, fy, fz) plane. The information (~I') of the image G3 projected in the second stage reduces information loss (four-dimensional information) about the subject's eye 12. Therefore, the above-described double projection method makes it possible to correct, for example, a distorted OCT image into an image equivalent to a normal microscope image. Furthermore, since information loss is reduced, the resolution is maintained, and it becomes possible to generate an OCT image with higher accuracy than when the thinly formed four-dimensional aperture A4 is not used.

[0056] That is, the 4-dimensional aperture A4 (4-dimensional opening) is a quantity that does not depend on the object frequency, The object frequency is defined by an optical system with a first numerical aperture and an optical system with a second numerical aperture. In this embodiment, the four-dimensional aperture can be expressed as a window function capable of expressing a physical quantity determined by the configuration of the optical system in the OCT system. In addition, in this embodiment, the object frequency is a physical quantity that expresses the subject's eye 12 using light components. Since the object frequency is not dependent on ν, it is a uniform four-dimensional physical quantity in the ν direction. Note that the frequency ν is the optical frequency of the light source and also the optical frequency of the signal light. The value of a three-dimensional function obtained by fz integrating a four-dimensional function (obtainable image frequency) obtained by multiplying this object frequency by the four-dimensional aperture A4 is acquired as a detection value by the optical system. In other words, the value of a three-dimensional function indicating the fz integral of a four-dimensional function obtained by multiplying the object frequency by the four-dimensional aperture A4 is acquired by a sensor in the optical system of the OCT system.

[0057] Note that when the NA value is finite, the four-dimensional aperture A4 has a finite thickness. Therefore, when using a four-dimensional aperture A4 with a finite thickness, an aperture surface may be defined within the four-dimensional aperture A4. This aperture surface is preferably a predetermined surface within the four-dimensional aperture A4 that is farthest from the origin (for example, the outermost surface of the four-dimensional aperture A4, which is the surface within the four-dimensional aperture A4 that is farthest from the origin).

[0058] The frequency of the OCT image used in the correction of the OCT image using the above-mentioned 4-dimensional aperture A4 The information can be expressed by the following equation (1).

[0059]

number

[0060] Here, τ represents the distance in the depth direction of the eye 12 (in the example of time-domain OCT, the adjustment amount for adjusting the optical path length in the reference optical system 20D, for example, the movement amount of a mirror).

[0061] The information (~I) of the image G2 projected on the four-dimensional aperture A4 can be expressed as follows (2):

[0062]

number

[0063] The information (~I') of the image G3 projected from the four-dimensional aperture A4 can be expressed as follows (3).

[0064]

number

[0065] The control device 16 uses the image processor 17, which operates under the control of the CPU 16A, to generate an OCT image using the above-mentioned equations (1) to (3). The process of generating the OCT image will be described later.

[0066] Next, the configuration of the optical system in the OCT system according to this embodiment will be further described with reference to Fig. 8. Note that in Fig. 8, the wide-angle optical system 30 is omitted for simplicity of description.

[0067] The sensor 20B of the OCT unit 20 includes a pair of lenses 20B-1 and a detecting element 20B-2. The sensor 20B collimates the light branched by the first optical coupler 20C, i.e., interference light resulting from interference between the measurement light reflected by the fundus and the reference light, into parallel light using the pair of lenses 20B-1, and then focuses the light on the detecting element 20B-2.

[0068] The reference optical system 20D includes a pair of lenses 20D-1 and a mirror 20D-2. In the reference optical system 20D, the light branched by the first optical coupler 20C, i.e., the measurement light, is collimated into parallel light by the pair of lenses 20D-1 and then converged on the mirror 20D-2. The mirror 20D-2 is configured to be movable in the optical axis direction (the direction indicated by the arrow τ in FIG. 8). The light reflected by the mirror 20D-2 is reflected by the first lens 20D-1 via the pair of lenses 20D-1. The light is returned to the optical coupler 20C as a reference light.

[0069] In FIG. 8, a configuration in which the mirror 20D-2 is movable is applied as the reference optical system 20D, but the OCT system according to this embodiment is not limited to a configuration in which the mirror 20D-2 is movable, and may be fixed. In other words, the OCT system according to this embodiment is a TD-OCT (Time-Domain OCT) system known as a time-domain OCT system. It can be applied to various types of OCT systems, such as swept-source OCT (SS-OCT), a wavelength-swept type known as Fourier-domain OCT, and spectral-domain OCT (SD-OCT) that uses a spectrometer.

[0070] Therefore, the OCT system may be configured according to the OCT system to be used. For example, when applying time-domain OCT (TD-OCT), the mirror 20D-2 may be moved to perform sweeping. When applying SD-OCT, a type of Fourier-domain OCT, the mirror 20D-2 may be fixed to perform spectral detection. For spectral detection, a light source that emits multiple light beams at multiple wavelengths may be used. When applying SS-OCT, a one-pixel detector may be used for the detecting element 20B-2, and the mirror 20D-2 may be fixed to sweep the wavelength of a broadband light source. When performing wavelength sweeping, a broadband light source, such as a laser device that emits broadband laser light for wavelength sweeping, may be used as the light source 20A. Furthermore, as an optical system with zero NA, an optical system of an OCT system using full-field illumination that uniformly illuminates an object on the irradiated side, such as the subject's eye 12, or that collectively illuminates a predetermined area on the irradiated side may be used. That is, the technology of the present disclosure is not limited to the above-described laser scanning optical system that scans with laser light, but can also be applied to an optical system that uses a CCD (Charge Coupled Device) camera, etc. In this case, a CCD camera including an element such as a CCD may be used as the detection element 20B-2.

[0071] The illumination / detection optical system 20E includes a second optical coupler 200, an illumination optical system 210, and a detection optical system 220. The second optical coupler 200 has a function of guiding light emitted from the light source 20A (measurement light branched by the first optical coupler 20C) to the illumination optical system 210 as illumination light, and a function of guiding light from the detection optical system 220 (i.e., returned light from the subject's eye 12) to the first optical coupler 20C (i.e., toward the sensor 20B) as detection light. Therefore, the subject's eye 12 is illuminated with light propagating through the illumination optical system 210 as light from the light source 20A, and returned light (reflected light from the subject's eye 12) of the light that has propagated through the illumination optical system 210 and irradiated the subject's eye 12 propagates through the detection optical system 220 and is incident on the sensor 20B as measurement light. In FIG. 8, the optical path of the irradiation optical system 210 in the irradiation and detection optical system 20E is shown by a solid line, and the optical path of the detection optical system 220 is shown by a dotted line.

[0072] The irradiation optical system 210 includes a pair of lenses, a lens 212 and a lens 214. The lens 212 is disposed so that one end face of the irradiation-side fiber 211 is located at the focal position of the incident side of the lens 212 on the optical axis of the irradiation optical system 210. The irradiation-side fiber 211 is formed of a single-mode fiber, and the other end face is connected to the second optical coupler 200. The lens 214 is disposed so that the reflecting surface of the optical scanner 22 is located at the focal position of the exit side of the lens 214 on the optical axis of the irradiation optical system 210. Therefore, the lens 212 collimates the light from the light source 20A (the measurement light branched by the first optical coupler 20C) into parallel light, and the lens 214 converges the parallel light collimated by the lens 212 onto the reflecting surface of the optical scanner 22. The light reflected by the optical scanner 22 is then collimated into parallel light by the lens 12B of the subject's eye 12 and irradiates the fundus 12C. Therefore, the light from the light source 20A that passes through the irradiation optical system 210 is irradiated onto the fundus 12C of the subject's eye 12 as parallel light.

[0073] The irradiation optical system 210 is an optical system that emits parallel light toward the subject's eye 12, thereby forming an optical system with an NA of zero. The NA of the irradiation optical system 210 is an example of the "first numerical aperture" of the technology of the present disclosure. The irradiation optical system 210 is also an example of the "optical system with a first numerical aperture" of the technology of the present disclosure.

[0074] The detection optical system 220 includes a beam splitter 222 and a pair of lenses, namely, a lens 214 and a lens 216. The beam splitter 222 is disposed between the lenses 212 and 214 in the irradiation optical system 210, and extracts return light (reflected light) from the subject's eye 12 by its reflection function. The beam splitter 222 is disposed such that its reflective surface is located at the focal position on the exit side of the lens 214, on the optical axis of the irradiation optical system 210, of the return light (reflected light) from the subject's eye 12. The lens 224 is disposed such that its reflective surface is located at the focal position on the entrance side of the lens 224, on the optical axis of the detection optical system 220. The lens 226 is disposed such that one end face of a detection-side fiber 228 is located at the focal position on the exit side of the lens 226, on the optical axis of the detection optical system 220. The detection-side fiber 228 is formed by a single-mode fiber, and the other end face is connected to the second optical coupler 200. Therefore, the lens 224 collimates the light from the beam splitter 222 into parallel light, and the lens 226 converges the parallel light collimated by the lens 224 onto the end face of the detection-side fiber 228. Therefore, in the detection optical system 220, light reflected at a point on the fundus 12C of the subject's eye 12 is emitted toward the sensor 20B.

[0075] The detection optical system 220 is an optical system having a focal point on the side of the subject's eye 12, and thus has a NA different from that of the irradiation optical system 210, and forms an optical system with a finite NA. The NA of the detection optical system 220 is an example of the "second numerical aperture" of the technology of the present disclosure. The detection optical system 220 is also an example of the "optical system with a second numerical aperture" of the technology of the present disclosure.

[0076] In this embodiment, an OCT image is generated in the ophthalmic apparatus 110 using information with reduced information loss of four-dimensional information obtained using an OCT system including the above-mentioned zero-NA irradiation optical system 210. The OCT image is generated by executing an image processing program using an image processor 17 that operates under the control of the CPU 16A. Note that, although this embodiment describes a case where an OCT image is generated in the ophthalmic apparatus 110, it goes without saying that the OCT image may also be generated by an external device such as a server 140.

[0077] The ROM 16C of the ophthalmologic apparatus 110 or the memory 17M of the image processor 17 stores an image processing program shown in FIG.

[0078] The ROM 16C and the memory 17M are examples of the "memory" of the technology of the present disclosure. The CPU 16A is an example of the "processor" of the technology of the present disclosure. The image processing program is an example of the "program" of the technology of the present disclosure.

[0079] In the ophthalmologic apparatus 110 according to this embodiment, the CPU 16A reads and executes an image processing program to realize various functions. The image processing program includes a display control function, an image processing function, and a processing function. That is, when the CPU 16A executes the image processing program having these functions, the CPU 16A operates as a display control unit 204, an image processing unit 206, and a processing unit 208, as shown in FIG. 9. The image processing function includes an image processing function using the above-described two-stage processing method (double projection method).

[0080] Next, the image processing according to this embodiment will be described in detail with reference to Fig. 10. The CPU 16A of the ophthalmic apparatus 110 reads and executes an image processing program from the ROM 16C or the memory 17M, thereby realizing the image processing shown in the flowchart of Fig. 10. The image processing process shown in FIG. 10 is an example of an image processing method according to the present disclosure.

[0081] In step S200, the image processing unit 206 of the CPU 16A acquires OCT data from the image processor 17. The OCT data is data obtained by performing OCT imaging on the subject's eye 12 using the ophthalmic apparatus 110. The OCT data includes data at positions with different depths in the optical axis direction (Z-axis direction). The OCT data is obtained by performing OCT imaging using the ophthalmic apparatus 110 as described above.

[0082] In step S202, the image processing unit 206 executes a first stage of processing in which information (OCT data) obtained by the OCT system is projected onto a four-dimensional aperture. That is, the image processing unit 206 expresses the acquired OCT data using the above equation (1), and derives frequency information of the OCT image using the above equation (2) as a process of projecting frequency information (I) of the OCT image G1 onto a thinly formed four-dimensional aperture A4. The derived information is temporarily stored in RAM 16B.

[0083] In the next step S204, the image processing unit 206 executes a second-stage process of projecting the information projected onto the four-dimensional aperture A4 into three-dimensional space. That is, the image processing unit 206 performs a process of projecting the information (~I) of the image G2 projected onto the four-dimensional aperture A4 in the ν (=2π / ω) direction (within the (fx, fy, fz) plane). In the second-stage process, the image processing unit 206 derives information on the OCT image after double projection projected into three-dimensional space from the four-dimensional aperture A4 using the above equation (3) as a process of projecting the information on the OCT data projected onto the four-dimensional aperture A4 into three-dimensional space. The derived information is temporarily stored in RAM 16B.

[0084] Next, in step S206, the image processing unit 206 generates an OCT image using the information projected by the double projection method. The generated OCT image is stored in the RAM 16B by the processing unit 208.

[0085] The OCT image corrected using the double projection method described above may be generated at a predetermined depth in the optical axis direction, i.e., the depth direction of the subject's eye 12, or at multiple different depths. For example, an OCT image may be generated at a predetermined depth, such as 10 times the focal depth, based on the focal position of the detection optical system 220 on the subject's eye 12 side. Alternatively, multiple OCT images may be generated at different depths based on the focal position, or at a predetermined number of positions at predetermined intervals. When multiple OCT images are generated, each of the multiple OCT images may be stored in RAM 16B or memory 17M. The predetermined depth, the different depths, and the predetermined number may be predetermined and can be set arbitrarily by the user, for example.

[0086] Furthermore, when generating the above-described OCT image, image processing such as noise removal may be performed to improve the sharpness of the image.

[0087] 10 is performed by the image processing unit 206, whereby an OCT image at a predetermined depth is generated, for example, based on the focal position on the subject's eye 12 side of the detection optical system 220. The generated OCT image has reduced information loss and maintains resolution, resulting in a highly accurate OCT image that faithfully reflects the state of the fundus of the subject's eye 12.

[0088] In the image processing described above, a process for generating information on a display screen for displaying the generated OCT images may be added. The process for generating information on a display screen for displaying the OCT images generates information on a display screen for displaying predetermined sample OCT images side by side. It is possible. Furthermore, when multiple OCT images are generated, it is possible to generate information on a display screen that displays the multiple OCT images side by side. When controlling the display of multiple OCT images side by side, for example, by generating information on a display screen that displays a group of OCT images side by side in a direction that increases in depth, it is possible to visualize changes in the size, shape, and other aspects of the subject's eye 12 in the depth direction and provide this to the user.

[0089] The OCT image obtained by correction using the double projection method described above from information on a single point detected by the ophthalmic device 110 is corrected, for example, from a distorted OCT image as shown in FIG. 11B to an OCT image equivalent to a normal microscope image as shown in FIG. 11A. FIG. 11A shows an example in which the illumination / detection optical system 20E in the OCT unit 20 is configured so that the NA of the illumination optical system 210 and the NA of the detection optical system are different, and the OCT image is corrected using the double projection method. Here, the NA of the illumination optical system 210 is zero by irradiating the subject's eye with a parallel beam of light, and the NA of the detection optical system 220 is 0.9. FIG. 11A also shows an OCT image generated at a depth position 30 times the focal depth. FIG. 11B shows a comparative example in which the NA of the illumination optical system 210 and the NA of the detection optical system 220 are configured so that they match, at 0.9.

[0090] 11A, by applying the OCT system according to this embodiment, it is possible to obtain an OCT image as an image of one point (point image) from information on one detected point on the subject's eye 12. On the other hand, as shown in Fig. 11B, if the NAs of the irradiation optical system 210 and the detection optical system 220 are matched, the OCT image will have a distorted shape, and the obtained image will reflect a deformed state of the fundus of the subject's eye 12. Therefore, as can be seen from Figs. 11A and 11B, by forming a thin four-dimensional aperture A4 and generating an OCT image from information obtained by the double projection method in which the four-dimensional aperture A4 is projected, it is possible to generate an OCT image with high accuracy.

[0091] As described above, according to this embodiment, the illumination optical system 210 and the detection optical system 220 have different NAs, with one optical system (the illumination optical system 210 in the above example) having a zero NA. This allows the aperture for an OCT image in four-dimensional space that takes frequency into account to be treated as a thin aperture (four-dimensional aperture A4) that can suppress the influence even when performing fz integration. Using such a thin four-dimensional aperture A4, the information of the OCT image projected by the double projection method reduces information loss (four-dimensional information) about the subject's eye 12. Therefore, correcting the OCT image using the above-described image processing makes it possible to correct, for example, a distorted OCT image to an image equivalent to a normal microscope image. Furthermore, because information loss is reduced, resolution is maintained, making it possible to generate an OCT image with higher accuracy than when a thin four-dimensional aperture A4 is not used.

[0092] In the above embodiment, the image processing (FIG. 10) is described as being performed by the ophthalmic device 110, but the technology of the present disclosure is not limited to this, and may be performed by any of the ophthalmic device 110, the server 140, the viewer 150, or an additional image processing device further provided on the network 130, or a combination of any of these.

[0093] As described above, the technique of the present disclosure preferably realizes image processing using information obtained by utilizing a thinly formed four-dimensional aperture A4, and therefore includes the following techniques.

[0094] (First Technology) an acquisition unit that irradiates light from a light source onto an irradiated object using an optical system with a first numerical aperture, and detects interference light between signal light, which is returned from the irradiated object by the irradiated light and propagated through an optical system with a second numerical aperture, and reference light, which is obtained by dividing the light from the light source, and acquires information indicating the interference light; a processing unit that performs a first process of projecting information representing the interference light onto a four-dimensional frequency aperture formed by an optical system with the first numerical aperture and an optical system with the second numerical aperture in a four-dimensional space of a frequency of the light source and a three-dimensional light frequency representing the illuminated object, and a second process of projecting the projected information onto the three-dimensional space; An image processing device comprising:

[0095] The image processing unit 206 is an example of the "acquisition unit" and the "processing unit" of the technology of the present disclosure.

[0096] (Second Technology) a detection unit that detects interference light between signal light obtained by irradiating the eye to be examined with light from a light source and reference light obtained by splitting the light from the light source; an illumination optical system formed with a first numerical aperture so as to illuminate the eye to be examined with light from the light source; a detection optical system formed with a second numerical aperture different from the first numerical aperture so that return light from the subject's eye due to the light irradiated by the irradiation optical system is propagated to the detection unit as the signal light; a processing unit that performs a first process of projecting, based on information indicating the interference light detected by the detection unit, the information indicating the interference light onto a four-dimensional frequency aperture formed by an optical system with the first numerical aperture and an optical system with the second numerical aperture in a four-dimensional space defined by the frequency of the light source and a three-dimensional light frequency indicating the eye to be examined, and a second process of projecting the projected information onto the three-dimensional space; an image generating unit that generates a plurality of images corresponding to a plurality of planes having different depths in the optical axis direction based on the information processed by the processing unit; An ophthalmic device comprising:

[0097] The sensor 20B is an example of an "acquisition unit" of the technology of the present disclosure. The irradiation optical system 210 is an example of an "irradiation optical system" of the technology of the present disclosure, and the detection optical system 220 is an example of a "detection optical system" of the technology of the present disclosure. The image processing unit 206 is an example of a "processing unit" and an "image generation unit" of the technology of the present disclosure.

[0098] Although the technology of the present disclosure has been described above using embodiments, the technical scope of the technology of the present disclosure is not limited to the scope described in the above embodiments. Various modifications or improvements can be made to the above embodiments without departing from the gist of the technology, and such modifications or improvements are also included in the technical scope of the disclosed technology.

[0099] In the above embodiment, the processing is performed by executing a program stored in a storage device such as a memory, but at least a part of the processing of the program may be realized by hardware. The processing flow of the program described in the above embodiment is also an example, and unnecessary steps may be deleted, new steps may be added, or the processing order may be changed within the scope of the gist.

[0100] Furthermore, in order to execute the processing in the above-described embodiment by a computer, a program in which the above-described processing is written in code that can be processed by a computer may be stored on a storage medium such as an optical disk and distributed.

[0101] In the above-described embodiment, a CPU is used as an example of a general-purpose processor. However, in the above-described embodiment, the term "processor" refers to a processor in a broad sense, and may include a general-purpose processor (e.g., a CPU: Central Processing Unit, etc.) or a dedicated processor (e.g., a GPU: Graphics Processing Unit, ASIC: Application Specific Integrated Circuit, FPGA: Field Programmable Gate Array, programmable logic devices, etc.

[0102] Furthermore, the operation of the processor in the above-described embodiments may not only be performed by a single processor, but may also be performed by multiple processors working together, or may be performed by multiple processors located in physically separate locations working together.

[0103] All documents, patent applications, and technical standards described herein are incorporated by reference herein to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference. In addition, the disclosure of Japanese Patent Application No. 2022-048770, filed March 24, 2022, is incorporated by reference in its entirety herein.

Claims

1. An image processing method in an image processing device performed by a processor, irradiating the light from the light source onto the illuminated object through an optical system with a first numerical aperture, detecting interference light between signal light, which is returned from the illuminated object by the irradiated light and propagated through an optical system with a second numerical aperture, and reference light, which is obtained by dividing the light from the light source, and acquiring information indicating the interference light; a first process of projecting information representing the interference light onto a four-dimensional frequency aperture formed by an optical system with the first numerical aperture and an optical system with the second numerical aperture in a four-dimensional space of the frequency of the light emitted from the light source and the three-dimensional frequency of the light representing the illuminated object; and a second process of projecting the projected information onto the three-dimensional space. An image processing method comprising:

2. the image processing device is provided in an ophthalmic device, The object to be irradiated is the eye to be inspected. The image processing method according to claim 1 .

3. the information indicating the interference light is OCT data obtained by detection by a detection unit that detects the interference light in an optical coherence tomography device included in the image processing device, The processor: The OCT data is acquired as information indicating the interference light. The image processing method according to claim 1 .

4. The information indicating the interference light is obtained by applying OCT data obtained by detecting the interference light using a detection unit in a time domain optical coherence tomography or a Fourier domain optical coherence tomography. The image processing method according to claim 3 .

5. The processor: generating a plurality of images corresponding to a plurality of planes at different depths based on the OCT data; The image processing method according to claim 3 .

6. The processor: Acquire information indicating the interference light obtained by the signal light from the optical system with the first numerical aperture, which has a numerical aperture of zero or a numerical aperture greater than zero, and the optical system with the second numerical aperture, which is greater than the first numerical aperture. The image processing method according to claim 1 .

7. The processor: and acquiring information indicating the interference light obtained by the signal light from the optical system with the first numerical aperture that irradiates the light from the light source onto the illuminated object with a parallel beam and the optical system with the second numerical aperture that is a predetermined numerical aperture. The image processing method according to claim 5 .

8. The processor: Acquire information indicating the interference light obtained by the signal light from an optical system including an optical system with the first numerical aperture NA that satisfies the condition 0≦NA≦0.

2. The image processing method according to claim 6.

9. Generate information for a display screen that displays the information projected into the three-dimensional space as an image. The image processing method according to claim 1 .

10. An image processing device comprising a memory storing a program and a processor, The processor reads the program from the memory and irradiating the light from the light source onto the illuminated object through an optical system with a first numerical aperture, detecting interference light between signal light, which is returned from the illuminated object by the irradiated light and propagated through an optical system with a second numerical aperture, and reference light, which is obtained by dividing the light from the light source, and acquiring information indicating the interference light; a first process of projecting information representing the interference light onto a four-dimensional frequency aperture formed by an optical system with the first numerical aperture and an optical system with the second numerical aperture in a four-dimensional space of the frequency of the light emitted from the light source and the three-dimensional frequency of the light representing the illuminated object; and a second process of projecting the projected information onto the three-dimensional space. An image processing device that performs this.

11. a detection unit that detects interference light between signal light obtained by irradiating the eye to be examined with light from a light source and reference light obtained by splitting the light from the light source; an illumination optical system formed with a first numerical aperture so as to illuminate the eye to be examined with light from the light source; a detection optical system formed with a second numerical aperture different from the first numerical aperture so that return light from the subject's eye due to the light irradiated by the irradiation optical system is propagated to the detection unit as the signal light; a processing unit that performs a first process of projecting the information indicating the interference light detected by the detection unit onto a four-dimensional frequency aperture formed by the optical system with the first numerical aperture and the optical system with the second numerical aperture in a four-dimensional space defined by the frequency of the light emitted from the light source and the three-dimensional frequency of the light indicating the eye to be examined, based on the information indicating the interference light detected by the detection unit, and a second process of projecting the projected information onto the three-dimensional space; an image generating unit that generates a plurality of images corresponding to a plurality of planes having different depths in the optical axis direction based on the information processed by the processing unit; An ophthalmic device comprising:

12. On the computer, irradiating the light from the light source onto the illuminated object through an optical system with a first numerical aperture, detecting interference light between signal light, which is returned from the illuminated object by the irradiated light and propagated through an optical system with a second numerical aperture, and reference light, which is obtained by dividing the light from the light source, and acquiring information indicating the interference light; a first process of projecting information representing the interference light onto a four-dimensional frequency aperture formed by an optical system with the first numerical aperture and an optical system with the second numerical aperture in a four-dimensional space of the frequency of the light emitted from the light source and the three-dimensional frequency of the light representing the illuminated object; and a second process of projecting the projected information onto the three-dimensional space. A program that executes a process.

Images