JP2023122379A - Ophthalmologic imaging apparatus, control method of ophthalmologic imaging apparatus, and program - Google Patents

Abstract

To provide an ophthalmologic imaging apparatus capable of executing accurate measurement by an inexpensive and simple configuration without using an additional optical element in a configuration for disposing an optical path length adjusting mechanism in a measurement optical system.SOLUTION: An ophthalmologic imaging apparatus includes: an interference optical system for detecting multiplexed light acquired by multiplexing return light of measurement light from an eye to be examined obtained by irradiating the eye to be examined with the measurement light, and reference light, and acquiring an interference signal; an optical path length changing part for changing an optical path length of the measurement light; a focus position changing part for changing a focus position of the measurement light; a scanning part for scanning the measurement light with the eye to be examined; and a control part for controlling the optical path length changing part, the focus position changing part, and the scanning part. The control part sets at least one of a scanning angle of the scanning part and the position of the focus position changing part on the basis of the position of the optical path length changing part.SELECTED DRAWING: Figure 7

Description

The present disclosure relates to an ophthalmic imaging apparatus, a control method for an ophthalmic imaging apparatus, and a program.

As an ophthalmologic imaging apparatus, an apparatus (OCT apparatus) for acquiring a tomographic image of an eye to be examined using optical coherence tomography (OCT) using low-coherence light has been put into practical use. In the OCT apparatus, since the axial length of the eye to be examined differs from patient to patient, the optical path length adjusting mechanism is adapted to match the optical path length difference between the measurement optical system and the reference optical system to generate interference light. provided in the optical system.

Patent Document 1 discloses a configuration in which an optical path length adjusting mechanism for moving a collimator lens and a fiber end in the optical axis direction is arranged in a measurement optical system. Such a configuration has the advantage that the reference optical system does not emit reference light into space, and can be configured inexpensively and simply using only fibers without using optical elements such as lenses and mirrors. Furthermore, Patent Document 2 discloses a configuration for moving a corner cube arranged in a measurement optical system as an optical path length adjusting mechanism.

JP 2012-75641 A JP 2014-140542 A

However, since the configuration of Patent Document 1 drives the collimator lens and the fiber end, which are part of the measurement optical system, it is affected by linear accuracy errors and collimation errors of the drive system, and the imaging position of the measurement light shifts. may occur and the measurement accuracy may be degraded. In addition, the configuration of Patent Document 2 has the advantage of being able to reduce the effects of linear accuracy errors by driving corner cubes with retroreflection characteristics, but the corner cubes themselves are expensive, and the reflection system is used as part of the measurement optical system. Additional provision in the middle may complicate the device. In addition, in general photographing apparatuses, a method of correcting optical system misalignment by image processing such as horizontal movement and rotational movement of an image is frequently used. However, in tomographic imaging using an OCT apparatus, for axial misalignment that is not included in the plane corresponding to the tomographic image, the image does not contain information on the target region to be corrected according to the misalignment. is difficult to correct by

In view of the above problems, one embodiment of the present disclosure is a configuration in which an optical path length adjustment mechanism is arranged in a measurement optical system, without using an additional optical element, with a low cost and simple configuration, and performs highly accurate measurement. One object is to provide an ophthalmologic imaging apparatus capable of

A fundus oculi observation device according to an embodiment of the present disclosure detects combined light obtained by combining measurement light returned from an eye to be inspected with measurement light and reference light. an interference optical system for acquiring an interference signal; an optical path length changing unit for changing the optical path length of the measurement light; a focus position changing unit for changing the focus position of the measurement light; a scanning unit that scans measurement light; and a control unit that controls the optical path length changing unit, the focus position changing unit, and the scanning unit, wherein the control unit controls the position of the optical path length changing unit. , at least one of the scanning angle of the scanning unit and the position of the focusing position changing unit.

According to one embodiment of the present disclosure, in a configuration in which an optical path length adjustment mechanism is arranged in a measurement optical system, it is possible to perform highly accurate measurement with a low cost and simple configuration without using additional optical elements.

1 shows a schematic configuration example of an OCT apparatus according to Example 1. FIG. 4 shows a schematic configuration example of a control unit according to the first embodiment; 4 shows an example of a screen display according to the first embodiment; FIG. 10 is a diagram for explaining fundus tracking processing according to the first embodiment; 4 shows an example of driving the coherence gate according to the first embodiment. 8 shows an example of observation results of spots of measurement light according to Example 1. FIG. FIG. 4 is a diagram for explaining a correction method according to the first embodiment; FIG. 5 is a flowchart of an example of a correction coefficient setting method according to the first embodiment; 5 is a flowchart of an example of a series of shooting processes according to the first embodiment; FIG. 10 is a diagram for explaining a correction method according to Example 2; 10 is a flowchart of an example of a correction coefficient setting method according to the second embodiment; 10 is a flowchart of an example of a series of imaging processes according to Example 2;

Exemplary embodiments for carrying out the present disclosure will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions of components, etc. described in the following examples are arbitrary and can be changed according to the configuration of the device to which the present disclosure is applied or various conditions. Also, the same reference numbers are used in the drawings to indicate identical or functionally similar elements.

(Example 1)
An OCT apparatus, which is an example of an ophthalmic imaging apparatus according to a first embodiment of the present disclosure, and a control method for the OCT apparatus will be described below with reference to FIGS. 1 to 9 . The OCT apparatus according to this embodiment corrects the scanning angle of the scanner based on the position of the coherence gate of the OCT optical system.

<Configuration>
The OCT apparatus according to the present embodiment is provided with a fundus image capturing unit that captures a two-dimensional fundus image and a tomographic image capturing unit that captures a three-dimensional tomographic image of the fundus of the subject's eye using information based on optical interference. It is First, with reference to FIG. 1, a schematic configuration of an OCT apparatus according to this embodiment will be described. FIG. 1 shows a schematic configuration of an OCT apparatus and its optical system according to this embodiment. In the following description, the direction substantially coinciding with the line-of-sight direction of the subject's eye E is defined as the Z direction. A plane perpendicular to the Z direction is the XY plane, the horizontal direction is the X direction, and the vertical direction is the Y direction.

The OCT apparatus is provided with an optical head section 100 , a spectroscope 200 and a control section 300 . Further, the control unit 300 is provided with a display unit 310 and an input unit 340 . The configurations of the optical head unit 100, the spectroscope 200, and the control unit 300 will be described in order below.

<Configuration of Optical Head Unit 100 and Spectroscope 200>
The optical head unit 100 is provided with an optical system for capturing two-dimensional images and tomographic images of the anterior segment Ea of the eye E to be examined and the fundus oculi Ef. Various optical systems arranged in the optical head unit 100 will be described below.

In the optical head unit 100, an objective lens 101 is arranged facing the eye E to be examined. A first dichroic mirror 102 and a second dichroic mirror 103 functioning as an optical path splitter are arranged on the optical axis L1 of the objective lens 101 . By the first dichroic mirror 102 and the second dichroic mirror 103, the optical path of the anterior eye observation system (optical axis L2), the optical path of the fundus imaging system (optical axis L3), and the optical path of the measurement optical system (optical axis L5) are It branches for each wavelength band.

A lens 120 , a prism 121 , a diaphragm 122 , a lens 123 , and an image sensor 124 are arranged on the optical axis L 2 in the reflection direction of the second dichroic mirror 103 . The image sensor 124 is a monochrome sensor with sensitivity in the infrared region. An anterior segment observation system for observing the anterior segment Ea is configured by the optical members and the like arranged on the optical axis L2.

Image sensor 124 is connected to control unit 300 . Image sensor 124 sends a signal corresponding to the detected light to controller 300 . The control unit 300 can generate an anterior segment observation image based on the signal received from the image sensor 124 and display it on the display unit 310 . In addition, the anterior segment observation light source 125 arranged near the objective lens 101 illuminates the anterior segment Ea of the eye E to be examined.

A perforated mirror 131, an imaging diaphragm 132, a focus lens 133, an imaging lens 134, a third dichroic mirror 135, and an image sensor 136 are arranged on the optical axis L3 of the first dichroic mirror 102 in the transmission direction. The perforated mirror 131 has an opening in the center. The focus lens 133 is held by a drive unit such as a motor (not shown) controlled by the control unit 300 so as to be movable in the optical axis direction indicated by the arrow in the drawing. The focus of the fundus imaging system can be adjusted by moving the focus lens 133 on the optical axis L3. The optical path on the optical axis L3 is split by the third dichroic mirror 135 into an optical path leading to the image sensor 136 and an optical path leading to the fixation lamp 137 for each wavelength band.

The image sensor 136 is a fundus image sensor that has sensitivity to visible light and infrared light, and that serves both for moving image observation and still image photography. The image sensor 136 sends a signal corresponding to the detected light to the controller 300 . The control unit 300 can generate a fundus observation image or a fundus image (fundus front image) based on the signal received from the image sensor 136 and display it on the display unit 310 . The fixation light 137 emits visible light to prompt the subject to fixate. In addition, the fixation lamp 137 may be provided with an aperture (not shown) for cutting the luminous flux necessary for photographing the fundus.

Also, the dioptric correction lens 138 can be inserted on the optical axis L3 using a drive unit such as a motor (not shown). Also, the diopter correction lens 138 can be pulled out from the optical axis L3 by using the driving section in the same manner. The control unit 300 controls the driving unit to control the insertion/removal of the dioptric correction lens 138, so that the focus of the fundus imaging system can be adjusted in a wider diopter range.

A corneal baffle 140, a relay lens 141, a focus target unit 142, a lens 143, and a ring slit 144 are arranged in this order on the optical axis L4 in the reflection direction of the perforated mirror 131. FIG. The corneal baffle 140 has a light blocking point in the center. The ring slit 144 has a ring-shaped slit opening. A lens baffle 145 as a light shielding member having a light shielding point and a dichroic mirror 146 having characteristics of transmitting infrared light and reflecting visible light are arranged on the optical axis L4.

The focus visual target unit 142 is an optical member that provides a visual target for focusing using the focus lens 133. In this embodiment, split bright lines are emitted as an example of the visual target. The focus optotype unit 142 according to this embodiment has a split optotype member movable along the optical axis L4 in conjunction with the focus lens 133 . Also, the split optotype member is configured to be able to be inserted into and pulled out of the optical path of the optical axis L4 by a drive section such as a motor (not shown) controlled by the control section 300 .

The split bright line emitted by the focus optotype unit 142 passes through the relay lens 141 and is reflected by the perforated mirror 131 toward the second dichroic mirror 103 . The split bright line reflected by the perforated mirror 131 is projected onto the fundus Ef of the subject's eye E via the second dichroic mirror 103 , the first dichroic mirror 102 and the objective lens 101 . The control unit 300 can calculate the amount of focus shift by detecting the position of the split bright line from the fundus observation image.

A condenser lens 147 and a white LED light source 148 are arranged in the reflection direction of the dichroic mirror 146 . The white LED light source 148 is a photographing light source in which a plurality of white LEDs that emit visible pulsed light are arranged. A condenser lens 149 and an infrared LED light source 150 are arranged in the transmission direction of the dichroic mirror 146 . The infrared LED light source 150 is an observation light source in which a plurality of infrared LEDs emitting stationary infrared light are arranged. The driving of the white LED light source 148 and the infrared LED light source 150 is controlled by the controller 300 .

The objective lens 101, the dichroic mirror 146, the optical members therebetween, and the condenser lenses 147 and 149 constitute an illumination optical system for illuminating the fundus oculi Ef. The fundus Ef of the subject's eye E can be illuminated with light from the white LED light source 148 or the infrared LED light source 150 via the illumination optical system. A fundus photographing system is configured by the optical members on the optical axes L3 and L4.

A lens 151, a mirror 152, an XY scanner 153, a focus lens 154, a collimator lens 155-1, and a fiber end 155-2 are arranged as a measurement optical system on the optical axis L5 in the reflection direction of the first dichroic mirror 102. be. The XY scanner 153 includes an X scanner 153-1 and a Y scanner 153-2. The X scanner 153-1 and the Y scanner 153-2 are composed of arbitrary deflection means such as a galvanomirror, for example, and function as scanning units for scanning the fundus Ef of the eye E to be inspected with measurement light. The vicinity of the central position of the X scanner 153-1 and the Y scanner 153-2 is optically conjugate with the position of the pupil of the eye E to be examined. In FIG. 1, the optical path between the X scanner 153-1 and the Y scanner 153-2 is configured within the plane of the paper, but actually is configured in the direction perpendicular to the plane of the paper. Further, the scanning unit that scans the measurement light may be configured using a single MEMS mirror or the like that can deflect the light in two-dimensional directions.

In this embodiment, the X scanner 153-1 can scan the measurement light in the X direction, and the Y scanner 153-2 can scan the measurement light in the Y direction orthogonal to the X direction. In this embodiment, an example in which scanning is performed with the X direction as the main scanning direction and the Y direction as the sub-scanning direction will be described, but the scanning direction is not limited to this. The main scanning direction and the sub-scanning direction in such scanning may be directions that intersect each other. For example, the Y direction may be the main scanning direction, and the X direction may be the sub-scanning direction. Further, oblique directions having X-direction and Y-direction components that intersect each other may be used as the main scanning direction and the sub-scanning direction. Also, the scanning pattern may be, for example, 3D scanning, radial scanning, cross scanning, Lissajous scanning, circle scanning, raster scanning, or the like.

The measurement light source 157 is a light source that emits light for obtaining measurement light to be incident on the measurement optical path. In this embodiment, the measurement light in the OCT optical system is emitted from the fiber end 155-2 of the optical fiber 156-2 as a light source, and the fiber end 155-2 has an optically conjugate relationship with the fundus Ef of the eye E to be examined. . The fiber end 155-2 is arranged at the focal position of the collimator lens 155-1, and the measurement light is emitted as a parallel beam from the fiber end 155-2 acting as a light source through the collimator lens 155-1. A coherence gate 155 is formed by the collimator lens 155-1 and the fiber end 155-2.

The focus lens 154 is a lens for adjusting the focus of the OCT optical system, and is driven in the direction of the optical axis indicated by the arrow in the drawing by a drive section such as a motor (not shown) controlled by the control section 300 . Focus adjustment is performed so that the measurement light is imaged on the fundus oculi Ef. The focus lens 154 is arranged between the fiber end 155-2, which serves as a measurement light source, and the X scanner 153-1 and Y scanner 153-2, which function as scanning units. By the focus adjustment described above, the image of the measurement light emitted from the fiber end 155-2 can be formed on the fundus Ef of the eye E to be examined, and the return light from the fundus Ef can be efficiently transmitted to the optical fiber 156-2. can return well.

Next, the configuration of the optical path from the measurement light source 157, the reference optical system, and the spectroscope 200 will be described. The measurement optical system described above, optical members included in the optical path from the measurement light source 157, the reference optical system, and the spectroscope 200 constitute an OCT optical system. The measurement light source 157, the optical coupler 156, the optical fibers 156-1 to 156-4, the lens 158, the dispersion compensating glass 159, the reference mirror 160, and the spectroscope 200 constitute a Michelson interference system.

In this embodiment, an SLD (Super Luminescent Diode), which is a typical low coherence light source, is used as the measurement light source 157 . The light emitted from the measurement light source 157 has a center wavelength of 880 nm and a wavelength width of about 60 nm. Here, the wavelength width is an important parameter because it affects the resolution in the optical axis direction of the obtained tomographic image. As for the type of light source, an SLD is selected here, but it is sufficient if it can emit low-coherence light, and for example, an ASE (Amplified Spontaneous Emission) or the like can also be used. As the central wavelength of the measurement light, for example, the wavelength of near-infrared light can be used in view of measuring the eye. Also, due to the characteristics of the first dichroic mirror 102 and the second dichroic mirror 103, the optical path of the fundus imaging system (optical axis L3), the optical path of the measurement optical system (optical axis L5), and the anterior ocular observation optical path (optical axis L2). branched. Therefore, it is necessary to provide a certain amount of wavelength difference between the wavelengths used in each optical path. In this embodiment, the above wavelengths were selected as the SLD wavelengths from these points of view.

The optical fibers 156-1 to 156-4 are single-mode optical fibers connected to and integrated with the optical coupler 156-1. Light emitted from the measurement light source 157 is guided to the optical coupler 156 via the optical fiber 156-1. The light guided to the optical coupler 156 is split by the optical coupler 156 into measurement light directed toward the optical fiber 156-2 and reference light directed toward the optical fiber 156-3. Here, the optical coupler 156 functions as an example of a splitter that splits the light from the measurement light source 157 into measurement light and reference light.

As described above, in this embodiment, the measurement light in the OCT optical system is emitted from the fiber end of the optical fiber 156-2 as a light source. The measurement light passes through the optical path of the measurement optical system described above and irradiates the fundus Ef of the subject's eye E, which is an observation target, and reaches the optical coupler 156 again through the same optical path as return light due to reflection and scattering by the retina.

On the other hand, the reference light reaches the reference mirror 160 through the optical fiber 156-3, the lens 158, and the dispersion compensating glass 159 inserted to match the dispersion of the measurement light and the reference light, and is reflected. . The reference light reflected by the reference mirror 160 returns along the same optical path and reaches the optical coupler 156 again.

The reference light and the measurement light (return light) that reach the optical coupler 156 again are combined by the optical coupler 156 . Here, when the optical path length of the measurement light and the optical path length of the reference light are substantially the same, interference occurs due to this multiplexing. A coherence gate 155 composed of a collimator lens 155-1 and a fiber end 155-2 of the OCT optical system can be integrally adjusted in positional relationship in the direction of the optical axis indicated by the arrow in the figure by a drive unit such as a motor (not shown). is held to By using the coherence gate 155, it is possible to match the optical path length of the measurement light, which varies depending on the subject's eye E, with the optical path length of the reference light. The obtained interference light is guided to spectroscope 200 via optical fiber 156-4.

A spectroscope 200 is provided with a lens 201 , a diffraction grating 202 , a lens 203 and a line sensor 204 . After the interference light emitted from the optical fiber 156-4 becomes substantially parallel light through the lens 201, the light is separated by the diffraction grating 202 and imaged on the line sensor 204 by the lens 203. FIG. Each element in the line sensor 204 generates an interference signal according to the received light, and the line sensor 204 sends the interference signal to the controller 300 . The control unit 300 can sample the interference signal received from the line sensor 204 at predetermined timing, perform predetermined signal processing, and generate a tomographic image.

Further, the optical head section 100 is provided with a head driving section 170 . The head driving section 170 includes three motors (not shown). The control unit 300 can move the optical head unit 100 with respect to the subject's eye E in three-dimensional (X, Y, Z) directions by controlling the driving of the head driving unit 170 . Thereby, the control section 300 can align the optical head section 100 with respect to the eye E to be examined.

<Configuration of control unit 300>
Next, a schematic configuration of the control unit 300 will be described with reference to FIG. The control unit 300 includes an imaging control unit 301 , a storage unit 302 , an output control unit 303 , an acquisition unit 304 and an image processing unit 305 .

The imaging control section 301 is connected to the storage section 302 , the image processing section 305 , the optical head section 100 and the input section 340 . The imaging control section 301 controls each section of the optical head section 100 based on the input signal from the input section 340 .

Here, control at the time of photographing various images will be described. In the anterior segment observation image capturing, the imaging control unit 301 causes the anterior segment observation light source 125 to emit light, and the image sensor 124 receives return light from the anterior segment Ea. The image sensor 124 sends a signal corresponding to the received light to the acquisition unit 304 . The image processing unit 305 uses the signal acquired by the acquisition unit 304 to generate an anterior segment observed image.

In addition, the imaging control unit 301 can cause the infrared LED light source 150 to emit light to perform fundus observation image photography with the fundus camera. A fundus observation image obtained by fundus observation image capturing can be used for fundus observation and fundus tracking processing. The imaging control unit 301 drives the focus visual target unit 142 to acquire diopter information of the subject's eye E, and then drives the focus lens 133 so as to match the acquired diopter information in fundus observation image photography. . When focusing on a wider diopter range, the imaging control unit 301 inserts and removes the dioptric correction lens 138 on the optical axis L3 using a drive unit (not shown). Return light from the fundus oculi Ef is received by the image sensor 136 . The image sensor 136 sends a signal corresponding to the received return light to the acquisition unit 304 . The image processing unit 305 uses the signal acquired by the acquisition unit 304 to generate a fundus observation image.

Further, in photographing a fundus image by a fundus camera, the photographing control unit 301 corrects the dioptric power information of the subject's eye E obtained using the infrared LED light source 150 for aberration due to the difference in the wavelength of the light source. The position of the focus lens 133 is changed so as to match the degree position. After that, the imaging control unit 301 causes the white LED light source 148 to emit visible pulsed light, and the image sensor 136 receives return light from the fundus oculi Ef. The image sensor 136 sends a signal corresponding to the received return light to the acquisition unit 304 . The image processing unit 305 uses the signal acquired by the acquisition unit 304 to generate a fundus image.

In tomographic imaging, the imaging control unit 301 drives the focus lens 154 based on dioptric power information acquired using the focus target unit 142 . The imaging control unit 301 also sends a scanning control signal to the X scanner 153-1 and the Y scanner 153-2, and scans the fundus Ef of the eye to be examined E in the X and Y directions with the measurement light from the measurement light source 157. . The return light of the measurement light from the fundus oculi Ef is received by the line sensor 204 . The line sensor 204 sends an interference signal corresponding to the received return light to the acquisition unit 304 . The image processing unit 305 Fourier-transforms the interference signal acquired by the acquisition unit 304 and converts the obtained data into luminance or density information, thereby generating a tomographic image of the eye E in the depth direction (Z direction). do. Such a scanning method is called an A-scan, and the resulting tomographic image is called an A-scan image.

A plurality of A-scan images can be obtained by scanning the fundus Ef of the subject's eye E in a predetermined transverse direction with the XY scanner 153 with the measurement light for this A-scan. The image processing unit 305 can generate a two-dimensional tomographic image based on a plurality of A-scan images and scanning information. Thus, for example, a tomographic image on the XZ plane can be obtained by scanning in the X direction, and a tomographic image on the YZ plane can be obtained by scanning in the Y direction. A scanning method in which the eye to be inspected E is scanned with the measurement light in a predetermined transverse direction is called a B-scan, and the resulting two-dimensional tomographic image is called a B-scan image.

A plurality of B-scan images can be obtained by repeatedly scanning a predetermined photographing range on the subject's eye E in predetermined directions with the XY scanner 153 . For example, three-dimensional information in the XYZ space can be obtained by repeating B-scanning of the XZ plane while shifting the position in the Y direction. Such a scanning method is called C-scan, and data composed of a plurality of obtained B-scan images is called three-dimensional data. The image processing unit 305 can generate a front image (En-Face image) of the fundus oculi Ef of the subject's eye E by projecting the three-dimensional data in a predetermined depth range, for example. A front image generated in this manner is called an OCT front image (C-scan image).

The control unit 300 can capture various images by performing the above control using the imaging control unit 301 . Further, the imaging control unit 301 uses the image generated by the image processing unit 305, the image stored in the storage unit 302, and the like to perform fundus tracking processing to follow the movement of the subject's eye E, which will be described later. Each part of the optical head unit 100 can also be controlled. Furthermore, as will be described later, the imaging control unit 301 sets the scanning angle of the XY scanner based on the position of the coherence gate 155, thereby correcting the optical axis shift of the measurement light due to the driving of the coherence gate 155. be able to.

The acquisition unit 304 can acquire the signals output from the image sensors 124 and 136 and the interference signal output from the line sensor 204 as described above. Also, the acquisition unit 304 outputs various acquired signals to the image processing unit 305 .

Based on the signal output from the acquisition unit 304, the image processing unit 305 generates, for example, an anterior segment observation image, a fundus observation image, a fundus image, a B-scan image that is a tomographic image, three-dimensional data, an OCT front image, and the like. can be generated. Any known generation method may be used as a method for generating these images.

The storage unit 302 stores an anterior ocular segment observation image, fundus observation image, fundus image, B-scan image which is a tomographic image, three-dimensional data, an OCT front image, and the like of the subject eye E generated by the image processing unit 305. . In addition, the storage unit 302 stores, for example, an examination sequence defining a series of control procedures for executing examinations multiple times, analysis results of various images, imaging conditions at the time of image acquisition, so-called patient information regarding the subject's eye E, and the like. . Further, the storage unit 302 also stores various programs for controlling the above-described anterior segment observation image capturing, fundus observation image capturing and fundus image capturing using a fundus camera, and tomographic image capturing.

The output control unit 303 is connected to the storage unit 302 , the image processing unit 305 and the display unit 310 and can control the display of the display unit 310 . The output control unit 303 controls, for example, various images stored in the storage unit 302, such as an anterior segment observation image, a fundus observation image, a fundus image, a B-scan image that is a tomographic image, three-dimensional data, and an OCT front image. Patient information and the like can be displayed on the display unit 310 . The output control unit 303 can also receive various images generated from the image processing unit 305 and output them to the display unit 310 .

Here, the control unit 300 can be configured by a computer provided with a processor and memory. Note that the control unit 300 may be configured by a general computer, or may be configured by a computer dedicated to the OCT apparatus. Also, the control unit 300 may be, for example, a personal computer, and a desktop PC, a notebook PC, a tablet PC (portable information terminal), or the like may be used. Furthermore, the control unit 300 may be configured as a cloud-type computer in which some components are arranged in an external device.

Also, each component of the control unit 300 other than the storage unit 302 may be configured by a software module executed by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). Note that the processor may be, for example, a GPU (Graphical Processing Unit), an FPGA (Field-Programmable Gate Array), or the like. Also, each component may be configured by a circuit or the like that performs a specific function, such as an ASIC. Also, the storage unit 302 can be configured using an arbitrary memory or a storage medium such as an optical disk.

The display unit 310 is configured by an arbitrary display, and displays various information such as patient information, various images, and a mouse cursor according to the operation of the input unit 340 under the control of the output control unit 303 . The input unit 340 is an input device for giving instructions to the control unit 300, and specifically includes a keyboard and a mouse. Note that the display unit 310 may be configured by a touch panel display, and in this case, the display unit 310 can also be used as the input unit 340 .

<Inspection operation flow>
Next, the operation flow of inspection in this embodiment will be described with reference to FIG. FIG. 3 shows an example of a measurement screen displayed on the display unit 310. As shown in FIG. A left/right eye switching button 1001, a Capture button 1003, a Start button 1004, an anterior eye observation image 1101, a fundus observation image 1201, a tomographic image 1301, and a Scan Mode button 1501 are displayed on the measurement screen 1000 according to the present embodiment. . Also displayed on the measurement screen 1000 are sliders 1103, 1203, and 1302 for controlling various adjustments, and a frame 1202 for setting the imaging range of the tomographic image. Note that the tomographic image 1301 may be a preview image obtained by scanning the fundus oculi Ef roughly at high speed for various adjustments. Also, the relative positional relationship between the fundus observation image 1201 and the tomographic image 1301 may be stored in the storage unit 302 .

When starting the examination according to the present embodiment, the operator moves the cursor 1002 in the measurement screen 1000 shown in FIG. A scan mode is selected from the Mode button 1501 . Scan modes include, for example, Macula3D, Glaucoma3D, and Disc3D, and when the scan mode is switched, the optimal scan pattern and fixation position are set for each scan mode. Note that the scan mode may include other scan modes such as an OCTA (OCT Angiography) mode, a fundus imaging mode, and a fundus fluorescence imaging mode.

Scanning patterns of OCT include, for example, 3D scanning, radial scanning, cross scanning, Lissajous scanning, circle scanning, and raster scanning. In this embodiment, a case where 3D scanning is selected as the scanning pattern will be described.

Next, when the operator presses the Start button 1004 via the input unit 340, the control unit 300 automatically performs alignment adjustment, focus adjustment, and coherence gate adjustment to prepare for photographing. Here, alignment adjustment is adjustment for aligning the optical head unit 100 with respect to the eye E to be examined. Focus adjustment is adjustment for moving the focus lenses 133 and 154 in the optical axis direction in order to perform focus adjustment on the fundus oculi Ef. Further, the coherence gate adjustment is adjustment for moving the coherence gate 155 in the optical axis direction so that a tomographic image of the retina or the like can be observed at a desired position on the tomographic image display screen. Focus adjustment, alignment adjustment, and coherence gate adjustment may be performed by any known method.

For example, the imaging control unit 301 may obtain the displacement amount of the optical head unit 100 with respect to the eye E to be examined using the anterior eye observation image, and adjust the alignment of the optical head unit 100 with respect to the eye E to be examined. Note that the imaging control unit 301 uses the image of the anterior segment Ea divided vertically based on the light that has passed through the prism 121 to determine the distance of the optical head unit 100 to the eye E in the Z-axis direction (optical axis direction). can be detected.

Further, the imaging control unit 301 may perform focus adjustment of the fundus imaging system and the OCT optical system using the fundus observation image. For example, the imaging control unit 301 uses the vertically shifted split luminous lines in the fundus observation image as targets, and moves the focus lenses 133 and 154 so as to eliminate the vertical deviation of each target, thereby performing focus adjustment. It can be performed. In this embodiment, as described above, the split optotype member of the focus optotype unit 142 is driven along the optical axis L4 in conjunction with the focus lens 133. FIG.

The imaging control unit 301 may also perform coherence gate adjustment of the OCT optical system using the acquired tomographic image. For example, the imaging control unit 301 can perform coherence gate adjustment by moving the coherence gate 155 so that the image of the retinal layer is shown at a predetermined position in the tomographic image.

Further, the operator can finely adjust the alignment, focus, and coherence gate by operating the sliders 1103, 1203, 1302, etc. via the input unit 340. FIG. When finely adjusting the alignment, the operator operates the slider 1103 or a button (not shown) to view the anterior eye observation image 1101 and adjust the position and position of the optical head unit 100 in the Z direction with respect to the eye E to be examined. Alignment can be adjusted by moving the XY position. Further, by operating the slider 1203 , the operator can adjust the focus of the fundus imaging system and the OCT optical system while viewing the brightness of the fundus observation image 1201 and the tomographic image 1301 . Furthermore, the operator can adjust the coherence gate of the OCT optical system while viewing the tomographic image 1301 by operating the slider 1302 .

Furthermore, the operator can adjust the size and position of the frame 1202 on the fundus observation image 1201 to specify the imaging range of the tomographic image. The operator can start shooting by pressing the Capture button 1003 . When tomographic imaging is started, the imaging control unit 301 controls the XY scanner 153 to scan the fundus oculi Ef with measurement light based on the specified imaging range, and performs 3D scanning of the eye E to be examined.

The obtaining unit 304 obtains an interference signal obtained by 3D scanning of the eye E to be examined. The image processing unit 305 can generate a B-scan image of the subject's eye E, three-dimensional data, an OCT front image, and the like, based on the acquired interference signal. Various images generated by the image processing unit 305 are stored in the storage unit 302 . The output control unit 303 can cause the display unit 310 to display various kinds of information such as various images and patient information stored in the storage unit 302 . Although the operation in the OCT scan mode has been described here, in a fundus imaging scan mode such as the fundus imaging mode, a fundus front image may be captured by the fundus imaging system in response to the operation of the Capture button 1003 . In addition, an anterior segment imaging or the like may be performed according to the scan mode.

<Fundus Tracking Processing>
The fundus oculi Ef of the subject's eye E may move during imaging due to movements of the subject's eye E, such as known fine eye movements, and movements of the subject. If the fundus oculi Ef moves during imaging, the position to be photographed shifts. Therefore, the imaging control unit 301 can perform fundus tracking for correcting the position to be photographed by following the movement of the fundus oculi Ef. The fundus tracking process will be described below.

First, the control unit 300 acquires a reference fundus front image (reference image) for tracking. Specifically, the imaging control unit 301 controls the fundus imaging system of the optical head unit 100 to image the fundus oculi Ef immediately before starting tomographic imaging by the OCT optical system. Acquisition unit 304 acquires a signal output from image sensor 136 . The image processing unit 305 generates a front fundus image based on the acquired signal, and stores the generated front fundus image in the storage unit 302 as a reference image. After that, the imaging control unit 301 starts imaging a tomographic image, and performs subsequent processing in parallel while performing B-scan and C-scan by the OCT optical system.

The control unit 300 controls the fundus photographing system in the same manner as described above, and photographs the target fundus front image (target image). The control unit 300 also sends the target image generated by the image processing unit 305 and the reference image stored in the storage unit 302 to the imaging control unit 301 . The imaging control unit 301 calculates the positional deviation between the target image and the reference image as the amount of movement of the fundus oculi Ef that occurs while these images are acquired. The imaging control unit 301 performs correction control of the irradiation position of the measurement light by the XY scanner 153 based on the acquired movement amount of the fundus oculi Ef.

Here, an example of a method of calculating the amount of movement of the fundus oculi Ef using a reference image and a target image captured at two different times will be described. The imaging control unit 301 according to this embodiment calculates the amount of movement of the fundus oculi Ef using a template matching method. Specifically, the imaging control unit 301 sets ROI1 (first region of interest) in the reference image and stores the position of this ROI1 in the reference image. Here, the ROI1 can be a region that includes a feature with high contrast, such as a blood vessel, that exists in the reference image. Next, the imaging control unit 301 searches for ROI2 (second region of interest) having the highest correlation with ROI1 in the target image. The imaging control unit 301 calculates the relative difference between the position of ROI1 in the reference image and the position of ROI2 in the target image as the movement amount (displacement amount) of the fundus oculi Ef between two different times.

Now, with reference to FIG. 4, the fundus tracking processing described above will be described in detail. FIG. 4 shows an example of a reference image 401 and a target image 402, which are fundus front images of the same subject eye E photographed at different times. The imaging control unit 301 first sets the ROI 403 on the reference image 401 . The ROI 403 includes blood vessel bifurcations as features. Then, the imaging control unit 301 searches the target image 402 captured later, and searches for the ROI 404 that has the highest correlation with the ROI 403 . Let the position of the ROI 403 be (x1, y1) and the position of the ROI 404 be (x2, y2) in the coordinate system of the fundus image. , for example (x2-x1, y2-y1). Then, the imaging control unit 301 uses the displacement amount (dx, dy) to correct the scanning position of the measurement light on the fundus oculi Ef by the OCT optical system.

Note that, in this embodiment, the ROI is set by focusing on the contrast, and the ROI is searched using the correlation function. However, these methods are only an example of the fundus tracking process, and other methods such as the optical flow method, which can calculate the amount of movement of the image, can be used. Further, the amount of translation of the fundus front image is not limited to the calculation. For example, two or more ROIs may be set in the reference image, and the amount of rotation of the fundus oculi Ef may also be calculated from the calculation results of the respective amounts of movement. . Also, various known methods for detecting the movement of the fundus Ef or the subject's eye E can be applied to the fundus tracking process by the imaging control unit 301 .

Here, the movement of the fundus oculi Ef occurs not only in the XY directions but also in the Z direction. That is, if the subject's head is not sufficiently fixed and the forehead is separated from the apparatus, the subject's eye E moves and the optical path length of the measurement light with respect to the fundus oculi Ef increases. If the optical path length changes during imaging, the tomographic image of the retina or the like moves vertically in the tomographic image. Therefore, the control unit 300 can control the OCT optical system, capture a reference tomographic image for tracking, and store it in the storage unit 302 immediately before starting to capture a tomographic image. Then, the control unit 300 calculates the positional deviation in the vertical direction between the captured tomographic image and the reference tomographic image while capturing the tomographic image, and acquires the amount of movement of the fundus oculi Ef of the subject's eye E in the optical axis direction. . The imaging control unit 301 can drive the coherence gate 155, which is an optical path length adjusting unit, based on the calculated amount of movement of the fundus oculi Ef in the optical axis direction to correct the optical path length of the measurement light.

The amount of movement of the fundus oculi Ef in the optical axis direction may be calculated using various known methods such as the template matching method and the optical flow method. For example, the imaging control unit 301 may set ROIs in each tomographic image and obtain the relative difference between the ROIs as described above. For example, the method for calculating the amount of movement of the fundus oculi Ef in the optical axis direction may include detection of a characteristic portion having high contrast, such as the retinal pigment epithelium layer, among the retinal layers.

<Coherence Gate>
Next, details of the coherence gate 155 in the OCT optical system will be described with reference to FIGS. 5(a) and 5(b). 5(a) and 5(b) show the collimator lens 155-1 and the fiber end 155-2 in an enlarged manner. An example of driving to P2 is shown. Parallel light beams F1 and F2 that are emitted in parallel from the collimator lens 155-1 at positions P1 and P2 and reach the fundus oculi Ef are indicated by solid and broken lines, respectively. In order to simplify the explanation, the lenses and mirrors arranged on the optical path from the coherence gate 155 to the eye E are omitted. In the examples shown in FIGS. 5(a) and 5(b), the XY scanner 153 is oriented at the center of the fundus oculi Ef.

FIG. 5(a) shows an example in which the straight running accuracy of the driving system is ideal. In this example, the optical axis of the coherence gate 155 coincides with the optical axis L5 of the measurement optical system along the entire path from position P1 to position P2. In this case, since the parallel light beams F1 and F2 are both parallel light beams and the exit angle is maintained, there is no change in the state, and the conjugate relationship between the fiber end 155-2 and the center of the fundus oculi Ef is maintained. be

However, the actual straight running accuracy has a certain error. FIG. 5(b) shows an example in which the drive system has an error in the straightness accuracy and the trajectory of the coherence gate 155 is curved. In this example, the angle of the optical axis of the coherence gate 155 changes continuously with respect to the optical axis L5 of the measurement optical system on the path from position P1 to position P2. At the reference position (not shown) of the coherence gate 155, the XY scanner 153 adjusts the conjugate relationship between the fiber end 155-2 and the center of the fundus oculi Ef. However, when the parallel light beams F1 and F2 depart from the reference position and the emission angles of the parallel light beams F1 and F2 change, the reaching positions on the fundus oculi Ef change, and the conjugate relationship with the fiber end 155-2 shifts. In general, where θ is the exit angle of the light beam, f is the focal length of the optical system, and Y is the image height where the light beam arrives on the image plane, there is a relationship of Y=f×tan θ. There is a positive correlation in relation to the arrival position on the top.

If the drive of the coherence gate 155 causes a shift in the conjugate relationship between the fiber end 155-2 and the center of the fundus oculi Ef, a problem arises in photographing a tomographic image in the operation flow of examination. First, a shift occurs in the relative positional relationship between the fundus observation image 1201 and the tomographic image 1301 in FIG. Therefore, even if the frame 1202 is adjusted on the fundus oculi observation image 1201 and the scan area is specified, it becomes difficult to obtain a tomographic image at a desired position.

In addition, when the coherence gate position is adjusted by the slider 1302 while observing the tomographic image 1301 of the preview image, not only the normal vertical movement of the imaging target site in the display screen of the tomographic image, which is the B-scan image, but also Left-right movement occurs. In particular, when the object to be imaged moves in the C-scanning direction (sub-scanning direction), the position scanned with the measurement light deviates from the line to be scanned by the B-scan, so the object to be imaged is displayed in the preview image. will not be. Therefore, it becomes difficult to stably perform coherence gate adjustment.

Similarly, in the fundus tracking process, when the imaging control unit 301 drives the coherence gate 155 and corrects the optical path length of the measurement light with respect to the displacement of the eye to be examined E in the Z direction, the XY A misalignment occurs. Therefore, it becomes difficult to perform desired correction for movement of the subject's eye E in the XY directions.

As a general method for reducing the angular deviation of an optical system, there is a method using a retroreflective mirror (corner cube, retroreflector, etc.). A retroreflective mirror has the property of reflecting light rays 180 degrees toward the original direction even if the mirror itself is tilted. Therefore, it is conceivable to reduce the optical axis deviation by driving the retroreflective mirror as the optical path length adjusting means. However, the retroreflecting mirror is expensive and is a dedicated additional part, so the use of the retroreflecting mirror leads to an increase in cost. In addition, it is necessary to construct a reflection optical system around the coherence gate, which may make the apparatus complicated and large. The same is true when the drive system itself is to be highly accurate.

Further, as a method of correcting the displacement of the optical system by image processing, generally, there is a method of performing horizontal movement processing or rotational movement processing of the image. With respect to such a method, when the measurement light is shifted in the X direction (main scanning direction), it is effective to move the B-scan image in the horizontal direction. However, if the measurement light is misaligned in the Y direction (sub-scanning direction), the image does not include information on the imaging target site, and therefore correction by image movement processing is difficult.

<Scanner Correction>
Next, with reference to FIGS. 6(a) to 7(b), the principle of the method of correcting the optical axis deviation caused by driving the coherence gate 155 by the scanner according to the present embodiment will be described.

6(a) and 6(b) show an example in which a model eye (not shown) corresponding to the subject's eye E is placed at the measurement position and the optical axis deviation caused by driving the coherence gate 155 is observed. FIG. 6A shows five measurement light spots 602 on a chart 601 arranged at a position corresponding to the fundus of the model eye. The intersection point of the crosshairs of the chart 601 corresponds to the center of the fundus Ef of the eye E to be examined, and the distance from there is the amount of optical axis deviation. A shift in the vertical direction is a shift in the Y direction, and a shift in the horizontal direction is a shift in the X direction. The spot 602 moves between positions S1 and S2 as the coherence gate 155 is driven between positions P1 and P2, and its path depends on the linear accuracy of the drive system incorporated in the device. Both the deviation amount of the spot 602 and the linearity of the path of the spot 602 are random depending on each device.

FIG. 6B is a graph of the coordinates of the spot 602 on the chart 601. FIG. The horizontal axis indicates the position P of the coherence gate 155 and the vertical axis indicates the position of the spot 602 . 6B shows the reference position P0 of the coherence gate 155, the position P1 of the drive end of the coherence gate 155 on the optical head unit 100 side, and the position P2 of the drive end of the coherence gate 155 on the eye E side. ing. A solid line 603 indicates the X position of the spot 602 and a solid line 604 indicates the Y position of the spot 602 according to the position of the coherence gate 155 . By observing the spot 602 using the model eye in this way, position information of the spot 602 corresponding to the position of the coherence gate 155, in other words, information of deviation (optical axis deviation) of the irradiation point of the measurement light can be obtained. can be done.

Note that the observation method of the spot 602 in this embodiment is a method of photographing the chart 601 from the back side with a camera (not shown), but the observation method of the spot 602 is not limited to this. For example, the information on the optical axis deviation in the XY directions can also be acquired by a method of capturing the chart 601 by C-scanning and using a generated OCT front image (front image). In this case, for example, C-scans are performed at a plurality of coherence gate positions to generate a plurality of front images, and the displacement amount of each front image can be calculated as the optical axis displacement amount. Note that a technique such as template matching, for example, may be used to calculate the amount of positional deviation for each front image. Also, in this case, the photographing range may be arbitrary, and for example, it may be set to a range in which the displacement amount of the front image can be calculated by template matching of the front image.

Further, the method of observing the spot 602 is not limited to the configuration in which the reference chart is placed on the model eye. For example, the positional information of the spot 602 can be similarly obtained by arranging a chart at a predetermined position outside the optical path of the OCT optical system inside the apparatus, deflecting the measurement light by a scanner, and photographing the chart.

FIGS. 7(a) and 7(b) show an example of correcting optical axis deviation by a scanner. FIG. 7A shows the coherence gate 155, the XY scanner 153, and the subject's eye E in an enlarged manner. In addition, in FIG. 7A, other lenses and mirrors included in the OCT optical system are omitted for simplification of explanation. In the drawing, the coherence gate 155 is at the position P1, and the incident parallel light flux F1 is angularly shifted. The light beam passes through the focus lens 154 (not shown) and enters the Y scanner 153-2 with an angular deviation. At this time, if the Y scanner 153-2 is at the reference angle, the light beam advances to the X scanner 153-1 while maintaining the angular deviation in the direction indicated by the dashed line. On the other hand, when the Y scanner 153-2 is rotated by a predetermined amount Δθ, the light beam travels along the optical axis of the OCT optical system and reaches the center of the fundus Ef of the eye E to be examined, as indicated by the solid line. .

FIG. 7B is a graph showing the relationship between the position of the coherence gate 155 and the correction angle of the Y scanner 153-2. The horizontal axis indicates the position P of the coherence gate 155, and the vertical axis indicates the correction angle Δθ of the Y scanner 153-2. 7B shows the reference position P0 of the coherence gate 155, the position P1 of the drive end of the coherence gate 155 on the optical head unit 100 side, and the position P2 of the drive end of the coherence gate 155 on the eye E side. ing. A solid line 701 is a function curve representing a correction formula for the correction angle Δθ corresponding to the position P. FIG.

As a method of obtaining the correction formula, for example, the coherence gate 155 is arranged at a plurality of positions, the scanning angle of the scanner is actually adjusted, and the correction formula can be obtained by interpolating each adjustment amount. Further, for example, a correction formula may be generated from the position information of the spot 602 using the correspondence relationship between the scanning angle and the spot position on the fundus oculi Ef, such as the scale relationship between the scanning angle and the fundus oculi Ef acquired in advance. . Since the information obtained by either method is discrete, it is possible to obtain a correction formula capable of correcting the optical axis deviation over the entire movement range of the coherence gate 155 by fitting with polynomial approximation.

For example, if the degree of the polynomial is 4th, the correction formula uses the position P as a variable and the coefficients A ₄ to A ₀ as follows:
Δθ=A ₄ ×P ⁴ +A ₃ ×P ³ +A ₂ ×P ² +A ₁ ×P+A ₀
can be expressed as The coefficients A ₄ to A ₀ are stored in the storage unit 302, and the correction angle Δθ is calculated by the above correction formula using the stored coefficients A ₄ to A ₀ by the imaging control unit 301. By applying the correction angle Δθ to the scanning angle, the optical axis deviation can be corrected. Although the correction method for the Y scanner 153-2 has been described with reference to FIGS. 7A and 7B, the same correction method can be used for the X scanner 153-1. With such a process, the scanner can correct the optical axis deviation caused by driving the coherence gate 155 with a simple and inexpensive configuration.

<How to set the correction coefficient>
Next, an example of a method for setting correction coefficients according to this embodiment will be described with reference to FIG. FIG. 8 is a flowchart of an example of a correction coefficient setting method according to the present embodiment. In the correction coefficient setting method according to the present embodiment, first, in step S801, the model eye is placed at the measurement position with respect to the OCT apparatus in order to observe the spot 602 of the measurement light on the fundus of the model eye. The model eye may be arranged at a position corresponding to the position of the subject's eye E at the time of photographing.

Subsequently, in step S802, the imaging control unit 301 sets the scanning angles of the X scanner 153-1 and Y scanner 153-2 as reference angles. Here, the reference angle of the scanning angle is a scanning angle such that the spot 602 of the measurement light reaches the center of the fundus oculi Ef when the position of the coherence gate 155 is set at the reference position P0.

In step S803, the imaging control unit 301 sets the position of the coherence gate 155 to the drive end. In this embodiment, the imaging control unit 301 sets the position of the coherence gate 155 to the position P1 where the optical path length of the measurement optical system (the optical path length of the measurement light) becomes the longest.

Thereafter, processing is repeated in steps S804 to S807. In the repetitive process, the imaging control unit 301 sequentially processes while driving the coherence gate 155 over the entire drive range up to the opposite drive end, in other words, the position P2 where the optical path length of the measurement optical system becomes the shortest. is done.

First, in step S<b>805 , the image processing unit 305 acquires the position of the spot 602 on the chart 601 . For example, the image processing unit 305 can acquire the positions of the spots 602 by photographing the chart 601 from the back side with a camera, as described above. In this case, an image of the spot 602 obtained by a camera (not shown) is sent to the control unit 300, and the image processing unit 305 acquires the position of the spot 602 based on the image of the spot 602 received from the acquisition unit 304. can be done. Also, the image processing unit 305 may acquire the position of the spot 602 using the front image obtained by the C-scan. In this case, the image processing unit 305 compares, for example, a front image obtained by placing the coherence gate 155 at the reference position P0 and a front image obtained at the position P of the coherence gate 155 where the position of the spot 602 should be obtained. , the position of the spot 602 can be obtained. Furthermore, the image processing unit 305 may acquire the position of the spot 602 by photographing a chart arranged inside the device.

Subsequently, in step S806, the image processing unit 305 converts the position information of the spot 602 into a scanning angle. For example, the image processing unit 305 can perform the conversion processing by proportional calculation based on the scanning angle of view information obtained in advance, in other words, the correspondence relationship between the fundus position and the scanning angle, such as the scale relationship between the fundus position and the scanning angle. .

When the coherence gate 155 reaches the opposite drive end in step S807, the iterative process ends. Accordingly, information used for correction processing can be acquired. At the drive end on the opposite side, acquisition of the positional information of the spot 602 and conversion of the spot position into the scanning angle may be performed.

In step S808, the image processing unit 305 generates a table of scanning angles of the X scanner 153-1 and Y scanner 153-2 corresponding to each position of the coherence gate 155. FIG. More specifically, the image processing unit 305 associates each position of the coherence gate 155 in the repeated processing with the scanning angles of the X scanner 153-1 and the Y scanner 153-2 obtained by converting the position information of the spot 602 at that position. Create a table to be stored with

After that, in step S809, the image processing unit 305 performs polynomial fitting using the generated table. Accordingly, the image processing unit 305 calculates coefficients A ₄ to A ₀ which are fitting coefficients for calculating the correction angle Δθ of the scanning angle corresponding to the position of the coherence gate 155 .

In step S810, the image processing unit 305 causes the storage unit 302 to store the calculated fitting coefficients, thereby completing the correction coefficient setting processing. The timing of setting the correction coefficient can be set, for example, at the time of shipment from the factory or at the time of replacement of drive system parts for repair or the like. Note that when the chart is arranged inside the apparatus, it may be performed prior to each examination, may be performed for each imaging, or may be performed according to the operator's operation. Also, here, the configuration in which the control unit 300 calculates the correction coefficient has been described, but the correction coefficient is calculated as described above using a separate device or manually, and the calculated correction coefficient is stored in the storage unit of the control unit 300. 302 may be stored. The drive end in step S803 may be the position where the optical path length of the measurement optical system is the shortest, and in this case, the drive end on the opposite side is the position where the optical path length of the measurement optical system is the longest.

Next, with reference to FIG. 9, an example of a series of photographing processes including the correction process according to this embodiment will be described. FIG. 9 is a flowchart of an example of a series of imaging processes according to this embodiment. When the photographing process according to this embodiment is started, first, alignment adjustment is performed in step S901. The imaging control unit 301 can obtain the displacement amount of the optical head unit 100 with respect to the eye E using the anterior eye observation image, and adjust the alignment of the optical head unit 100 with respect to the eye E, as described above. The operator may operate the slider 1103 or the like to move and adjust the Z-direction position and the XY position of the optical head unit 100 with respect to the eye E while viewing the anterior eye observation image. .

In step S902, the imaging control unit 301 performs focus adjustment of the fundus imaging system and the OCT optical system using the fundus observation image as described above. The operator may operate the slider 1203 or the like to adjust the focus of the fundus imaging optical system and the OCT optical system while observing the brightness of the fundus observation image and the tomographic image.

In step S903, the imaging control unit 301 performs coherence gate adjustment of the OCT optical system using the acquired tomographic image as described above. The operator may operate the slider 1302 or the like to adjust the coherence gate position of the OCT optical system while viewing the tomographic image.

Next, in step S<b>904 , the imaging control unit 301 calculates a correction angle Δθ based on the position of the coherence gate 155 adjusted in step S<b>903 and the correction coefficients stored in the storage unit 302 . Specifically, the imaging control unit 301 substitutes the position of the coherence gate 155 and the correction coefficient stored in the storage unit 302 into the correction formula described above to calculate the correction angle Δθ.

In step S905, the imaging control unit 301 performs a C-scan or the like for the set imaging range to capture a tomographic image, three-dimensional data, or the like. At this time, the imaging control unit 301 applies (adds or subtracts) the correction angle Δθ calculated in step S904 to the scanning angle of the XY scanner 153 corresponding to the set imaging range, and determines the scanning angle of the XY scanner 153. correct. As a result, it is possible to correct the optical axis deviation caused by the coherence gate position, and to perform imaging at an appropriate position.

In step S906, the output control unit 303 causes the display unit 310 to display various images captured in step S905. When the display processing in step S906 ends, a series of shooting processing ends.

As described above, the fundus oculi Ef of the subject's eye E may move due to involuntary eye movement or movement of the subject during photographing. Therefore, in step S905, the imaging control unit 301 can perform the fundus tracking process described above. In this case, when the coherence gate position moves due to the fundus tracking process, the imaging control unit 301 calculates the correction angle Δθ in accordance with the coherence position after the movement in the same manner as in step S904, and calculates the scanning angle of the XY scanner 153. can be corrected.

As described above, the OCT apparatus according to the present embodiment combines the return light of the measurement light from the eye E to be examined, which is obtained by irradiating the eye to be examined E with the measurement light, and the reference light. It includes an OCT optical system that functions as an example of an interference optical system that detects wave light and acquires an interference signal. The OCT apparatus also includes a coherence gate 155 , a focus lens 154 , an XY scanner 153 and an imaging control section 301 . Here, the coherence gate 155 is arranged in the optical path of the measurement light and functions as an example of an optical path length changing section that changes the optical path length of the measurement light. Also, the focus lens 154 functions as an example of a focus position changing unit that changes the focus position of the measurement light. Furthermore, the XY scanner 153 functions as an example of a scanning unit that scans the subject's eye E with measurement light. Also, the imaging control unit 301 functions as an example of a control unit that controls the coherence gate 155 , focus lens 154 , and XY scanner 153 . The imaging control unit 301 sets the scanning angle of the XY scanner 153 based on the position of the coherence gate 155 . Note that the coherence gate 155 includes a collimator lens 155-1 and a fiber end 155-2.

The imaging control unit 301 corrects the scanning angle of the XY scanner 153 corresponding to the imaging range based on the position of the coherence gate 155 . More specifically, the imaging control unit 301 calculates the correction angle Δθ of the XY scanner 153 using a polynomial that approximates the displacement of the irradiation points of the measurement light corresponding to the multiple positions of the coherence gate 155 . The imaging control unit 301 sets the scanning angle of the XY scanner 153 by applying the calculated correction angle Δθ to the scanning angle of the XY scanner 153 corresponding to the imaging range.

With such a configuration, the OCT apparatus according to the present embodiment controls the XY scanner 153 to reduce the influence of the positional error of the measurement light caused by the driving of the coherence gate 155, thereby enabling the OCT optical system to perform measurement. It is possible to improve the accuracy. Therefore, in the configuration in which the optical path length adjustment mechanism is arranged in the measurement optical system, the OCT apparatus can perform highly accurate measurement with a low cost and simple configuration without using additional optical elements.

The OCT apparatus according to this embodiment further includes an image processing unit 305 that functions as an example of a generating unit that generates a tomographic image of the subject's eye E based on the interference signal. The imaging control unit 301 can perform tracking processing for changing the position of the coherence gate 155 so as to follow the movement of the eye E to be examined based on the tomographic image. The imaging control unit 301 also sets the scanning angle of the XY scanner 153 based on the position of the coherence gate 155 changed by the tracking process. As a result, the OCT apparatus can change the imaging range so as to follow the movement of the subject's eye E during imaging, and the influence of the error in the position of the measurement light due to the movement of the coherence gate 155 when changing the imaging range. can be reduced and the measurement accuracy can be improved.

Furthermore, the OCT apparatus according to the present embodiment includes a fundus imaging system that functions as an example of an imaging unit that captures a front fundus image of the eye to be examined E, and a display control unit that causes the display unit 310 to display the front fundus image of the eye to be examined E. and an output control unit 303 functioning as an example of. The output control unit 303 causes the display unit 310 to superimpose a frame 1202 representing the imaging range of the tomographic image corresponding to the interference signal on the front fundus image. Accordingly, the operator can set the imaging range of the tomographic image by operating the frame 1202 superimposed and displayed on the front fundus image, and the imaging control unit 301 determines the scanning angle corresponding to the imaging range. Information can be obtained.

The output control unit 303 can also cause the display unit 310 to display a slider 1302 that functions as an example of display for changing the position of the coherence gate 155 . As a result, the operator can change the position of the coherence gate 155 according to the desired imaging range while checking the tomographic image 1301 displayed on the display unit 310 .

In this embodiment, the X-direction scanning (main scanning) angle and the Y-direction scanning (sub-scanning) angle by the X scanner 153-1 and Y scanner 153-2 are corrected. On the other hand, the misalignment of the optical axis in the main scanning direction may be corrected by moving the B-scan image in the horizontal direction.

In this case, the imaging control unit 301 corrects the scanning angle of the Y scanner 153-2 by the correction process described above. After that, the image processing unit 305 generates a B-scan image based on the acquired interference signal, and performs horizontal movement processing on the B-scan image based on the position of the coherence gate 155 . As for the amount of deviation of the optical axis in the X direction to be corrected, a table may be created by associating the spot position obtained in step S805 with the position of the coherence gate 155, and a correction formula may be obtained by polynomial fitting or the like. .

Thus, in the OCT apparatus according to the modification of this embodiment, the image processing unit 305 functions as an example of an image processing unit that processes the tomographic image of the subject's eye E generated based on the interference signal. In this case, the imaging control unit 301 sets the scanning angle of the XY scanner 153 in the sub-scanning direction based on the position of the coherence gate 155, and the image processing unit 305 generates a tomographic image based on the position of the coherence gate 155. Move in the main scanning direction. In this case as well, the OCT apparatus has a low cost and simple configuration without using an additional optical element, reduces the influence of errors in the position of the measurement light caused by driving the coherence gate 155, and performs highly accurate measurements. be able to.

(Example 2)
An OCT apparatus according to a second embodiment of the present disclosure will be described below with reference to FIGS. The OCT apparatus according to this embodiment corrects the driving position of the focus lens based on the position information of the coherence gate of the OCT optical system. The configuration of the OCT apparatus according to this embodiment is the same as that of the OCT apparatus according to the first embodiment. Therefore, the constituent elements according to the present embodiment are denoted by the same reference numerals as those of the constituent elements according to the first embodiment, and the description thereof is omitted. The OCT apparatus according to the present embodiment will be described below, focusing on differences from the OCT apparatus according to the first embodiment.

<Focus lens correction>
The collimated state of the emitted light from the coherence gate 155 is ideally parallel, but in reality it may not be parallel due to manufacturing errors. In such a case, in this embodiment, the focus lens 154 corrects the focus state shift (defocus) of the OCT optical system caused by driving the coherence gate 155 . Other conditions of the optical system may be the same as in the first embodiment. However, in this embodiment, for simplification of explanation, it is assumed that the linear accuracy of the driving system of the coherence gate 155 is in an ideal state.

10(a) and 10(b) show an example in which the focus lens 154 corrects the deviation of the focus state. FIG. 10(a) illustrates the coherence gate 155, the focus lens 154, and the eye E to be examined. In addition, in FIG. 10A, other lenses and mirrors included in the OCT optical system are omitted for simplification of explanation.

In FIG. 10A, position P indicates the position of the coherence gate 155, and position Q indicates the position of the focus lens 154. In FIG. In the example shown in FIG. 10A, when the coherence gate 155 is placed at the reference position P0, the focus lens 154 is shown by a dashed line so that the light beam F3 forms an image on the fundus Ef of the eye to be examined E with emmetropia. It is adjusted to the reference position Q0.

Here, in the example shown in FIG. 10A, the positional relationship between the collimator lens 155-1 and the fiber end 155-2 has a distance longer than the ideal focal length, and the solid line emitted from the coherence gate 155 The light flux F3 shown is convergent light. If the light flux F3 is converged light instead of parallel light, the position of the coherence gate 155 causes a change in the imaging position of the OCT optical system. In the example shown in FIG. 10A, when the coherence gate 155 moves from the reference position P0 to the position P1 and the optical path length increases, the imaging position shifts toward the optical head unit 100 side. Therefore, when the coherence gate 155 moves to the position P1, the imaging position shifts as shown by the light beam F4 indicated by the dashed line, and the spot of the measurement light on the fundus Ef of the eye to be examined E is defocused. The defocus of the measurement light spot leads to a decrease in return light from the fundus Ef of the eye E to be inspected, which lowers the sensitivity of OCT imaging.

On the other hand, it is possible to correct defocus by controlling the position of the focus lens 154 . For example, when the focus lens 154 is moved from the reference position Q0 to the position Q1 on the subject's eye E side by the correction amount ΔQ, the image forming position of the light beam F4 moves further toward the subject's eye E side than the defocus position, and the fundus of the subject's eye E is moved. It can be imaged to Ef.

The correction amount ΔQ can be obtained using a model eye as in the first embodiment. For example, a spot 602 of the measurement light is observed on a chart 601 placed at a position corresponding to the fundus of the emmetropic model eye. Then, by driving the focus lens 154 and searching for the position of the focus lens 154 that minimizes the size of the spot 602 of the measurement light or maximizes the peak light amount, the focus lens 154 that optimizes the imaging state is selected. Explore location. By arranging the coherence gates 155 at a plurality of positions and performing the processing, it is possible to acquire the correspondence relationship between the positions of the coherence gates 155 and the correction amount ΔQ.

Note that, as a method for observing the spots in this embodiment, a method of photographing the chart 601 from the back surface with a camera can be used. In addition, the control unit 300 drives the focus lens 154 to determine the position of the focus lens 154 at which the peak or average value of the pixel values of the tomographic image (such as an A-scan image) captured using the measurement light is maximized. You can explore. In this case as well, the position of the focus lens 154 that optimizes the imaging state can be searched for.

FIG. 10B is a graph showing the relationship between the position of the coherence gate 155 and the correction position of the focus lens 154. In FIG. The horizontal axis indicates the position P of the coherence gate 155 and the vertical axis indicates the correction amount ΔQ of the focus lens 154 . 10B shows the reference position P0 of the coherence gate 155, the position P1 of the drive end of the coherence gate 155 on the optical head unit 100 side, and the position P2 of the drive end of the coherence gate 155 on the eye E side. ing. A solid line 901 is a function curve showing a correction formula for the correction amount ΔQ according to the position P. FIG.

As a method of obtaining the correction formula, for example, the coherence gate 155 is arranged at a plurality of positions, the position of the focus lens 154 is actually adjusted, and the correction formula can be obtained by interpolating each adjustment amount. However, since the information obtained in this way is discrete, similar to the first embodiment, the correction formula can correct the deviation of the focus state over the entire moving range of the coherence gate 155 by fitting with polynomial approximation. can be asked for.

Further, as in the first embodiment, the obtained coefficients of the polynomial are stored in the storage unit 302, and the shooting control unit 301 calculates the correction amount ΔQ using the stored coefficients using the above correction formula, A correction amount ΔQ is applied to the 154 positions. Specifically, the imaging control unit 301 moves the coherence gate 155 to the current position of the coherence gate 155 at the reference position Q0 adjusted so that the measurement light is focused on the eye E when the coherence gate 155 is at the reference position P0. The focus lens 154 is moved to a position to which the corresponding correction amount ΔQ is applied. Through such processing, defocus caused by driving the coherence gate 155 can be corrected by the focus lens 154 with a simple and inexpensive configuration without using an additional optical element.

<How to set the correction coefficient>
Next, with reference to FIG. 11, a flow of an example of a correction coefficient setting method according to this embodiment will be described. FIG. 11 is a flowchart of an example of a correction coefficient setting method according to this embodiment. In the correction coefficient setting method according to the present embodiment, first, in step S1101, the model eye is placed at the measurement position with respect to the OCT apparatus in order to observe the spot 602 of the measurement light on the fundus of the model eye. The model eye may be arranged at a position corresponding to the position of the subject's eye E at the time of photographing.

Subsequently, in step S1102, the imaging control unit 301 sets the position of the focus lens 154 to the reference position Q0. Here, the reference position Q0 of the focus lens 154 is the position where the spot 602 of the measurement light is imaged on the fundus oculi Ef when the coherence gate 155 is arranged at the reference position P0.

In step S1103, the imaging control unit 301 sets the position of the coherence gate 155 to the drive end. In this embodiment, the imaging control unit 301 sets the position of the coherence gate 155 to the position where the optical path length of the measurement optical system (the optical path length of the measurement light) becomes the longest.

After that, the processing is repeated in steps S1104 to S1107. In the repetitive processing, the imaging control unit 301 sequentially performs the processing while driving the coherence gate 155 over the entire driving range up to the drive end on the opposite side, in other words, the position where the optical path length of the measurement optical system is the shortest. .

First, in step S<b>1105 , the image processing unit 305 observes the spot 602 on the chart 601 and confirms the defocus state of the spot 602 . For example, as described above, the image processing unit 305 can photograph the chart 601 from the back side with a camera and confirm the defocus state of the spot 602 based on the size and peak light amount of the spot 602 . In this case, an image of the spot 602 obtained by a camera (not shown) is sent to the control unit 300, and the image processing unit 305 confirms the defocus state of the spot 602 based on the image of the spot 602 received from the acquisition unit 304. can do. Note that the image processing unit 305 may check the defocus state of the spot 602 based on the tomographic image.

Subsequently, in step S1106, the imaging control unit 301 drives the focus lens 154, and the image processing unit 305 acquires the position of the focus lens 154 when the spot 602 forms an image. The search for the position of the focus lens 154 is performed by searching for the position of the focus lens 154 that satisfies the conditions such as the minimum size of the spot 602 or the maximum peak light amount, as described above. can be done. In addition, the position of the focus lens 154 that maximizes the peak and average pixel values in the tomographic image captured using the measurement light is also searched for the position of the focus lens 154 that maximizes the imaging state. can.

When the coherence gate 155 reaches the opposite drive end in step S1107, the iterative process ends. Accordingly, information used for correction processing can be acquired. Note that observation of the spot 602 and acquisition of the position of the focus lens 154 where the spot 602 forms an image may also be performed at the drive end on the opposite side.

In step S<b>1108 , the image processing unit 305 generates a table of positions of the focus lens 154 corresponding to each position of the coherence gate 155 . More specifically, the image processing unit 305 generates a table that associates and stores each position of the coherence gate 155 in the repeated processing with the position of the focus lens 154 where the spot 602 is imaged.

After that, in step S1109, the image processing unit 305 performs polynomial fitting using the generated table. Thereby, the image processing unit 305 calculates a fitting coefficient for calculating the correction amount ΔQ of the position of the focus lens 154 corresponding to the position of the coherence gate 155 .

In step S1110, the image processing unit 305 causes the storage unit 302 to store the calculated fitting coefficients, thereby completing the correction coefficient setting processing. The timing of setting the correction coefficient can be set, for example, at the time of shipment from the factory or at the time of replacement of drive system parts for repair or the like. Also, here, the configuration in which the control unit 300 calculates the correction coefficient has been described, but the correction coefficient is calculated as described above using a separate device or manually, and the calculated correction coefficient is stored in the storage unit of the control unit 300. 302 may be stored. The drive end in step S1103 may be the position where the optical path length of the measurement optical system is the shortest, and in this case, the drive end on the opposite side is the position where the optical path length of the measurement optical system is the longest.

Next, with reference to FIG. 12, a series of shooting processing including correction processing according to the present embodiment will be described. FIG. 12 is a flowchart of an example of a series of imaging processes according to this embodiment. Note that the imaging process according to this embodiment is the same as the imaging process according to the first embodiment, except for the processes in steps S1204 and S1205. Therefore, for simplification of description, description of steps S1201, S1202, S1203, and S1206 is omitted.

After the coherence gate adjustment of the OCT optical system is performed in step S1203, the process proceeds to step S1204. In step S<b>1204 , the imaging control unit 301 calculates the correction amount ΔQ based on the position of the coherence gate 155 adjusted in step S<b>1203 and the correction coefficient stored in the storage unit 302 . Specifically, the imaging control unit 301 substitutes the position of the coherence gate 155 and the correction coefficient stored in the storage unit 302 into the correction formula described above, and calculates the correction amount ΔQ.

In step S1205, the imaging control unit 301 performs a C-scan or the like for the set imaging range to capture a tomographic image, three-dimensional data, or the like. At this time, the imaging control unit 301 applies the correction amount ΔQ calculated in step S1204 to the position of the focus lens 154 adjusted in step S1202 to correct the position of the focus lens 154 . Note that the position of the focus lens 154 adjusted in step S1202 may be the position adjusted when the coherence gate 155 is at the reference position P0, and this position is used as the reference position Q0 of the focus lens 154 for processing. . As a result, it is possible to correct the deviation of the focus state caused by the coherence gate position, and to perform the photographing in an appropriate focus state. It should be noted that the subsequent processing is the same as that of the first embodiment, so the description is omitted.

Also in this embodiment, in step S1205, the imaging control unit 301 can perform the above-described fundus tracking process. In this case, when the coherence gate position moves due to the fundus tracking process, the imaging control unit 301 calculates the correction amount ΔQ according to the coherence position after the movement in the same manner as in step S1204, and adjusts the position of the focus lens 154. can be corrected.

As described above, the imaging control unit 301 sets the position of the focus lens 154 based on the position of the coherence gate 155 . Specifically, the imaging control unit 301 adjusts the position of the focus lens 154 so that the measurement light is focused on the subject's eye E when the coherence gate 155 is at a predetermined position (reference position P0). A second position obtained by applying a correction amount ΔQ corresponding to the position P of the coherence gate 155 to the first position (reference position Q0) of 154 is set. Here, the imaging control unit 301 performs correction corresponding to the position P of the coherence gate 155 using a polynomial that approximates the defocus amounts of the measurement light corresponding to a plurality of positions of the coherence gate 155 changed from the reference position P0. Calculate the quantity ΔQ. Here, the defocus amount of the measurement light corresponds to the position of the focus lens 154 adjusted so that the imaging position of the OCT optical system matches the imaging region at each of the plurality of positions of the coherence gate 155 .

According to such a configuration, the OCT apparatus according to the present embodiment controls the focus lens 154 to reduce the influence of the focus error of the spot 602 caused by driving the coherence gate 155, thereby improving the measurement accuracy of the OCT optical system. It is possible to improve the accuracy. Therefore, in the configuration in which the optical path length adjustment mechanism is arranged in the measurement optical system, the OCT apparatus can perform highly accurate measurement with a low cost and simple configuration without using additional optical elements.

Further, the imaging control unit 301 according to the present embodiment can also perform tracking processing for changing the position of the coherence gate 155 so as to follow the movement of the subject's eye E based on the tomographic image. The imaging control unit 301 also sets the position of the focus lens 154 based on the position of the coherence gate 155 changed by the tracking process. Thereby, the OCT apparatus can change the imaging range so as to follow the movement of the subject's eye E during imaging. In addition, the OCT apparatus can reduce the influence of errors in the focus of the measurement light caused by the movement of the coherence gate 155 when changing the imaging range, and can improve the measurement accuracy.

In the first and second embodiments, examples of correcting errors in the position and focus of the spot 602 caused by driving the coherence gate 155 have been described. However, the spot 602 position and focus errors caused by driving the coherence gate 155 may actually occur simultaneously. In this case, by executing both the correction processes of the first and second embodiments, it is possible to reduce the effects of both errors and improve the measurement accuracy of the OCT optical system. The setting of the correction coefficient for the scanning angle and the setting of the correction coefficient for the focus lens position may be performed separately or together.

Also, in the first and second embodiments, the configuration for capturing the fundus oculi Ef of the subject's eye E and acquiring the fundus front image and the tomographic image has been described. However, the imaging target is not limited to the fundus oculi Ef. For example, the anterior segment Ea of the subject's eye E may be taken as an imaging target, and a front image or a tomographic image of the anterior segment Ea may be acquired. In this case, the fundus tracking process described above may be performed as the tracking process for the anterior segment Ea.

In addition, although the Michelson interferometer is used as the interferometer in Examples 1 and 2, a Mach-Zehnder interferometer may be used. Furthermore, although a fiber optical system using a coupler is used as the splitting means, a spatial optical system using a collimator and a beam splitter may be used. Also, the configuration of the optical head section 100 is not limited to the configuration described above, and part of the configuration included in the optical head section 100 may be configured separately from the optical head section 100 . Furthermore, the optical systems provided in the reflection and transmission directions of various dichroic mirrors may be provided in the transmission and reflection directions, respectively. Moreover, although various images are generated by the image processing unit 305 , they may be generated by a calculation unit (not shown) provided in the optical head unit 100 and sent to the control unit 300 . In this case, the acquisition unit 304 can acquire an anterior segment observation image, a fundus front image, a tomographic image, and the like from the optical head unit 100 and send them to the image processing unit 305 .

Furthermore, in the above-described first and second embodiments, the spectral domain OCT (SD-OCT) apparatus using the SLD as the light source was described as the OCT apparatus, but the configuration of the OCT apparatus according to the present invention is not limited to this. For example, the present invention can be applied to any other type of OCT apparatus such as a wavelength swept OCT (SS-OCT) apparatus using a wavelength swept light source capable of sweeping the wavelength of emitted light. For example, it can also be applied to an AO-OCT apparatus equipped with an adaptive optics system. In addition, in Examples 1 and 2, the structure of the fundus camera is used as the fundus observation system, but the structure for photographing the fundus observation image and the fundus image is not limited to this. For example, a structure of a scanning laser ophthalmoscope (SLO) may be used as a structure for photographing a fundus observation image and a fundus image.

(Other examples)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions. A computer has one or more processors or circuits and may include separate computers or a network of separate processors or circuits for reading and executing computer-executable instructions.

A processor or circuit may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), or a field programmable gateway (FPGA). Also, the processor or circuitry may include a digital signal processor (DSP), data flow processor (DFP), or neural processing unit (NPU).

Although the present invention has been described with reference to the examples, the present invention is not limited to the above examples. Inventions modified within the scope of the present invention and inventions equivalent to the present invention are also included in the present invention. In addition, the embodiments and modifications described above can be appropriately combined within the scope of the present invention.

153: XY scanner (scanning unit), 154: focus lens (focusing position changing unit), 155: coherence gate (optical path length changing unit), 301: imaging control unit (control unit)

Claims (13)

an interference optical system for acquiring an interference signal by detecting combined light obtained by combining the return light of the measurement light from the eye to be examined and the reference light obtained by irradiating the eye to be examined with the measurement light;
an optical path length changing unit that changes the optical path length of the measurement light;
a focus position changing unit that changes the focus position of the measurement light;
a scanning unit that scans the eye to be inspected with the measurement light;
a control unit that controls the optical path length changing unit, the focus position changing unit, and the scanning unit;
with
The ophthalmic photographing apparatus, wherein the control section sets at least one of a scanning angle of the scanning section and a position of the focusing position changing section based on the position of the optical path length changing section. 2. The ophthalmic imaging apparatus according to claim 1, wherein said optical path length changing section includes a collimator lens and a fiber end. 3. The ophthalmologic imaging apparatus according to claim 1, wherein said control section corrects the scanning angle of said scanning section corresponding to an imaging range based on the position of said optical path length changing section. 4. The ophthalmology clinic according to claim 3, wherein the control unit calculates the correction angle of the scanning angle using a polynomial that approximates deviations of the irradiation points of the measurement light corresponding to the plurality of positions of the optical path length changing unit. photographic equipment. The control unit adjusts the position of the focus position changing unit to the position of the focus position changing unit adjusted so that the measurement light is focused on the eye to be examined when the optical path length changing unit is at a predetermined position. The ophthalmologic imaging apparatus according to any one of claims 1 to 4, wherein the second position is set by applying a correction amount corresponding to the position of the optical path length changing unit to the first position. The control unit corrects the position of the optical path length changing unit using a polynomial that approximates defocus amounts of the measurement light corresponding to a plurality of positions of the optical path length changing unit changed from the predetermined position. 6. The ophthalmic imaging apparatus of claim 5, wherein the amount is calculated. further comprising a generation unit that generates a tomographic image of the eye to be inspected based on the interference signal;
The ophthalmologic imaging apparatus according to any one of claims 1 to 6, wherein the control section changes the position of the optical path length changing section so as to follow the movement of the subject's eye based on the tomographic image. 8. The ophthalmic photographing apparatus according to claim 7, wherein said control section sets at least one of a scanning angle of said scanning section and a position of said focus position changing section based on said changed position of said optical path length changing section. . further comprising an image processing unit that processes a tomographic image of the subject eye generated based on the interference signal;
The control unit sets a scanning angle of the scanning unit in the sub-scanning direction based on the position of the optical path length changing unit,
The ophthalmologic imaging apparatus according to any one of claims 1 to 8, wherein the image processing section moves the tomographic image in the main scanning direction based on the position of the optical path length changing section. an imaging unit that captures a front image of the subject's eye;
A display control unit that displays the front image on a display unit,
The ophthalmologic imaging apparatus according to any one of claims 1 to 9, wherein the display control unit causes the display unit to superimpose the imaging range of the tomographic image corresponding to the interference signal on the front image. The ophthalmologic imaging apparatus according to any one of claims 1 to 10, further comprising a display control section that causes a display section to display a display for changing the position of the optical path length changing section. A control method for an ophthalmic imaging apparatus, comprising:
The ophthalmic imaging device
an interference optical system for acquiring an interference signal by detecting combined light obtained by combining the return light of the measurement light from the eye to be examined and the reference light obtained by irradiating the eye to be examined with the measurement light;
an optical path length changing unit that changes the optical path length of the measurement light;
a focus position changing unit that changes the focus position of the measurement light;
a scanning unit that scans the eye to be inspected with the measurement light;
with
The control method includes setting at least one of the scanning angle of the scanning unit and the position of the focusing position changing unit based on the position of the optical path length changing unit. A program that, when executed by a computer, causes the computer to execute the ophthalmologic imaging apparatus control method according to claim 12.