Fundus imaging apparatus

Abstract

A fundus imaging apparatus according to a non-limiting embodiment projects illumination light emitted from an illumination optical system, which includes a light source and an optical scanner, onto the fundus of an eye to be examined, via a first curved mirror and a second curved mirror. The first curved mirror and the second curved mirror have different curvature distributions. Return light of the illumination light projected onto the fundus is detected by a light receiving optical system via the second curved mirror and the first curved mirror. Each of the first curved mirror and the second curved mirror has one or more focal points, and the first curved mirror and the second curved mirror are arranged so as to share one focal point. The light receiving optical system includes a first lens group, a second lens group disposed eccentrically to the first lens group, and an image sensor for detecting the return light passing through the first lens group and the second lens group.

Description

Fundus photography device

[0001] The present disclosure relates to a fundus imaging apparatus.

[0002] Various imaging modalities are used in ophthalmologic diagnosis and treatment. In recent years, devices capable of easily capturing images of the fundus of a subject's eye over a wide field of view have come to be used for screening and treating eye diseases. For example, a scanning laser ophthalmoscope (SLO) capable of capturing images over a field of view exceeding 80 degrees at a time is known. Patent Document 1 discloses a fundus imaging device that enables wide-field scanning of the retina by moving a two-dimensional parallel light beam using a polygonal mirror and a plane mirror to the subject's eye using a scanning movement means.

[0003] Furthermore, Patent Document 2 discloses a fundus imaging device that uses an elliptical concave mirror and a wide-angle lens to achieve fundus imaging with a wide angle of view. When imaging with this fundus imaging device, the patient must keep their face pressed against a pad provided on the device in order to position the eye to be examined appropriately for imaging.

[0004] Patent Documents 3 and 4 disclose fundus imaging devices that combine a rolling shutter with a fundus scan using slit-shaped illumination light to generate high-contrast images with a simple configuration. In particular, the fundus imaging device described in Patent Document 4 incorporates two elliptical concave mirrors in an optical system for performing fundus scanning using slit-shaped illumination light, enabling wide-angle imaging of the fundus.

[0005] JP-T-2009-543585 A JP-A-2022-184520 A U.S. Patent No. 7,831,106 WO 2022 / 124170

[0006] In general, fundus imaging devices capable of wide-angle imaging are large in size because they are equipped with a plurality of large elliptical concave mirrors (see, for example, FIG. 3A of Patent Document 2).

[0007] One object of the present disclosure is to provide a technique for miniaturizing a fundus imaging device capable of wide-angle imaging.

[0008] An exemplary aspect of an embodiment is a fundus imaging device for photographing the fundus of a test eye, comprising: an illumination optical system including a light source that generates illumination light and an optical scanner that deflects the illumination light; a first curved mirror that reflects the illumination light from the illumination optical system; a second curved mirror that has a curvature distribution different from that of the first curved mirror and reflects the illumination light reflected by the first curved mirror and guides it to the test eye; and a light receiving optical system that detects return light of the illumination light projected onto the fundus of the test eye via the second curved mirror and the first curved mirror, wherein each of the first curved mirror and the second curved mirror has one or more focal points, and the first curved mirror and the second curved mirror share a single focal point; and the light receiving optical system includes a first lens group, a second lens group that is eccentrically positioned with respect to the first lens group, and an image sensor that detects the return light that has passed through the first lens group and the second lens group.

[0009] According to an exemplary aspect of the embodiment, it is possible to reduce the size of a fundus imaging device capable of wide-angle imaging.

[0010] FIG. 1 is a schematic diagram showing the configuration of a fundus imaging device according to a non-limiting aspect of an embodiment. FIG. 2 is a schematic diagram showing the configuration of a fundus imaging device according to a non-limiting aspect of an embodiment. FIG. 3 is a schematic diagram for explaining the configuration of a fundus imaging device according to a non-limiting aspect of an embodiment. FIG. 4 is a schematic diagram for explaining the configuration of a fundus imaging device according to a non-limiting aspect of an embodiment. FIG. 5 is a schematic diagram for explaining the configuration of a fundus imaging device according to a non-limiting aspect of an embodiment. FIG. 6 is a schematic diagram for explaining the operation of a fundus imaging device according to a non-limiting aspect of an embodiment. FIG. 7 is a schematic diagram for explaining the operation of a fundus imaging device according to a non-limiting aspect of an embodiment.

[0011] Non-limiting embodiments of the present disclosure will now be described.

[0012] Any known technology can be combined with the embodiments. For example, any matter described in the documents cited in this disclosure can be combined with any aspect of the embodiments. Furthermore, at least one of any known document related to the technical field of the present disclosure, any known technology in a technical field similar to the technical field of the present disclosure, and any known technology in a technical field other than the technical field of the present disclosure can be combined with any aspect of the embodiments.

[0013] For example, the disclosures in Patent Document 4 (WO 2022 / 124170) can be incorporated by reference into the present disclosure. More generally, any technical matter disclosed by the applicant of the present application regarding technology related to the present disclosure (matters disclosed in patent applications, papers, etc.) can be incorporated by reference into the present disclosure.

[0014] Any two or more of the various non-limiting aspects of the embodiments may be at least partially combined.

[0015] At least a portion of the functionality of any aspect described in this disclosure is implemented using circuitry or processing circuitry. The circuitry or processing circuitry may be a general-purpose processor, a special-purpose processor, an integrated circuit, a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), a Field Programmable Gate Array (FPGA)), or a combination of these devices configured and / or programmed to perform at least some of the disclosed functions. Array), conventional circuitry, and any combination thereof. A processor is considered to be processing circuitry or circuitry, including transistors and / or other circuitry. In this disclosure, circuitry, unit, means, or similar terms refers to hardware that performs at least a portion of the disclosed functions or hardware that is programmed to perform at least a portion of the disclosed functions. The hardware may be hardware disclosed herein or known hardware that is programmed and / or configured to perform at least a portion of the described functions. In the case of a processor, where the hardware can be considered to be a type of circuitry, circuitry, unit, means, or similar terms refers to a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0016] <Overview of the Embodiments> One objective of the embodiments of the present disclosure is to reduce the size of a fundus imaging device capable of wide-angle imaging. The effects of the embodiments of the present disclosure are not limited to the effects achieved by achieving this objective. This disclosure describes several non-limiting aspects of the embodiments. It will be understood by those skilled in the art that each of the disclosed aspects achieves unique effects according to its features (configuration, operation, action, use, etc.).

[0017] For example, in conventional fundus imaging devices, the subject's eye must be positioned appropriately to capture images of the fundus with a wide angle of view. To achieve this, as described in paragraph 0030 of Patent Document 2 (JP 2022-184520 A), the subject must press their face against a pad provided on the device. This causes discomfort and places a significant burden on many subjects. This problem can be solved by several aspects of the embodiments of the present disclosure.

[0018] A first aspect of the embodiment is a fundus imaging device for imaging the fundus of a subject's eye, which includes an illumination optical system, a first curved mirror, a second curved mirror, and a light-receiving optical system. Some aspects of the fundus imaging device may further include elements other than these. For example, some aspects of the fundus imaging device may include three or more curved mirrors.

[0019] The illumination optical system includes a light source that generates illumination light. The illumination optical system further includes an optical scanner that deflects the illumination light generated by the light source. The first curved mirror reflects the illumination light generated by the illumination optical system. The second curved mirror reflects the illumination light reflected by the first curved mirror and guides it to the subject's eye. With this configuration, the fundus imaging device can project illumination light to various positions on the fundus of the subject's eye.

[0020] The shape of the first curved mirror (the reflective surface (concave reflective surface) that reflects illumination light) and the shape of the second curved mirror (the reflective surface (concave reflective surface) that reflects illumination light) are different from each other. In other words, the curvature distribution of the first curved mirror (the reflective surface (concave reflective surface) that reflects illumination light) and the curvature distribution of the second curved mirror (the reflective surface (concave reflective surface) that reflects illumination light) are different from each other.

[0021] The light-receiving optical system detects, via the second curved mirror and the first curved mirror, return light of the illumination light generated by the illumination optical system and projected onto the fundus of the subject's eye via the first curved mirror and the second curved mirror. In other words, the return light of the illumination light from the subject's eye is reflected by the second curved mirror and then reflected by the first curved mirror, guided to the light-receiving optical system, and detected by the light-receiving optical system.

[0022] In this aspect, the first curved mirror (the reflective surface (concave reflective surface) that reflects illumination light) has one or more focal points, and the second curved mirror (the reflective surface (concave reflective surface) that reflects illumination light) also has one or more focal points.

[0023] Furthermore, the first curved mirror and the second curved mirror share a single focal point, i.e., the single focal point of the first curved mirror and the single focal point of the second curved mirror are located at the same position.

[0024] In this aspect, the light receiving optical system includes a first lens group and a second lens group. The second lens group is disposed eccentrically with respect to the first lens group. That is, the optical axes of the first lens group and the second lens group are not aligned on the same line but are parallel to each other.

[0025] Furthermore, the light-receiving optical system of this aspect includes an image sensor that detects return light of the illumination light that has passed through the first lens group and the second lens group, and an image of the fundus can be constructed based on an output signal from the image sensor.

[0026] According to this aspect, fundus photography with a wide angle of view is possible by using an optical system including first and second curved mirrors that have different curvature distributions and share a common focal point to scan the fundus.

[0027] Furthermore, according to this aspect, the configuration for detecting the return light of the illumination light using a light-receiving optical system including first and second lens groups that are decentered relative to each other enables the use of first and second curved mirrors that are smaller than conventional ones. The reason for this is explained in more detail below. One of the factors that hinders the miniaturization of curved mirrors is the deterioration of the optical system's aberration performance. That is, because an optical system including two (or more) curved mirrors is not a coaxial optical system, miniaturizing the curved mirrors causes asymmetric aberrations (e.g., tilt of the image plane), deteriorating the aberration performance. This makes it difficult to correct aberrations in the subsequent optical system. Conventional technologies have not been able to correct such asymmetric aberrations. In contrast, this aspect uses a decentered optical system as the light-receiving optical system, making it possible to suppress asymmetric aberrations resulting from the miniaturization of the curved mirror. Therefore, according to this aspect, a fundus imaging device equipped with a curved mirror that is smaller than conventional ones can be realized. This makes it possible to miniaturize a fundus imaging device capable of wide-angle imaging.

[0028] A second aspect of the embodiment is the fundus imaging apparatus of the first aspect, wherein the image sensor of the light receiving optical system is disposed at an angle with respect to both the optical axis of the first lens group and the optical axis of the second lens group.

[0029] According to this aspect, the combination of the first and second lens groups, which are decentered relative to each other, and the tilted image sensor can enhance the effect of suppressing asymmetric aberrations caused by the miniaturization of the curved mirror. This makes it possible to miniaturize a fundus imaging device capable of wide-angle imaging. It is also possible to improve image quality.

[0030] In a third aspect of the embodiment, in the fundus imaging device of the first aspect, the light-receiving optical system further includes a third lens group that is eccentrically disposed with respect to both the first lens group and the second lens group, and the image sensor of the light-receiving optical system of this aspect detects return light of the illumination light that has passed through the first lens group, the second lens group, and the third lens group.

[0031] According to this aspect, it is possible to provide an example of a configuration in which return light of illumination light is detected using a light receiving optical system including three lens groups that are decentered relative to one another, which makes it possible to use first and second curved mirrors that are smaller than conventional ones, thereby enabling the miniaturization of a fundus imaging device that is capable of wide-angle imaging.

[0032] A fourth aspect of the embodiment is a fundus photography device of the third aspect, in which the image sensor of the light receiving optical system is tilted with respect to all of the optical axes of the first lens group, the second lens group, and the third lens group.

[0033] According to this aspect, the combination of the first, second, and third lens groups, which are decentered relative to one another, and the tilted image sensor can enhance the effect of suppressing asymmetric aberrations caused by the miniaturization of the curved mirror, thereby enabling the miniaturization of a fundus imaging device capable of wide-angle imaging.

[0034] A fifth aspect of the embodiment is the fundus imaging device of the third or fourth aspect, in which return light of illumination light from the subject's eye passes through the first lens group, the second lens group, and the third lens group in this order and is guided to the image sensor. Furthermore, the fundus imaging device of this aspect includes a first focusing mechanism as an element for adjusting the focus of the light-receiving optical system. The first focusing mechanism moves the second lens group, the third lens group, and the image sensor integrally. The movement direction is, for example, a direction along the optical axis of the second lens group (third lens group).

[0035] According to this aspect, the focus of the light receiving optical system can be adjusted according to the diopter of the subject's eye, etc. This makes it possible to reduce the size of a fundus imaging device capable of wide-angle imaging and also improve image quality.

[0036] A sixth aspect of the embodiment is a fundus imaging device of any of the first to fifth aspects, in which a first elliptical concave mirror is used as the first curved mirror and a second elliptical concave mirror is used as the second curved mirror.

[0037] According to this aspect, it is possible to provide a suitable configuration example for a fundus imaging device that is capable of wide-angle imaging and is compact.

[0038] A seventh aspect of the embodiment provides examples of dimensions of the first elliptical concave mirror and the second elliptical concave mirror in the fundus imaging device of the sixth aspect. In this aspect, the major axis of the first elliptical concave mirror and the major axis of the second elliptical concave mirror are each within the range of 70 to 80 mm. Also, the minor axis of the first elliptical concave mirror and the minor axis of the second elliptical concave mirror are each within the range of 50 to 60 mm.

[0039] According to this aspect, it is possible to provide a fundus imaging device capable of wide-angle imaging, equipped with an elliptical concave mirror smaller than conventional devices. In fact, conventional fundus imaging devices of the same type use elliptical concave mirrors with both major and minor axes exceeding 100 mm. In contrast, according to this aspect, it is possible to introduce an elliptical concave mirror with dimensions significantly smaller than conventional devices. The inventor's design allows the use of an elliptical concave mirror with dimensions about the size of a bowl, which hides part of the subject's eyes and nose, and the overall dimensions of the device can be reduced to about one-fourth of conventional dimensions.

[0040] An eighth aspect of the embodiment provides an example of the arrangement of the first elliptical concave mirror and the second elliptical concave mirror in the fundus imaging device of the sixth or seventh aspect, in which the first elliptical concave mirror and the second elliptical concave mirror are arranged such that a plane including the major axis of the first elliptical concave mirror and a plane including the major axis of the second elliptical concave mirror are non-parallel to each other.

[0041] For example, the first elliptical concave mirror may be arranged so that its major axis is oriented parallel to a horizontal plane, and the second elliptical concave mirror may be arranged so that its major axis is oriented parallel to a plane inclined relative to the horizontal plane.

[0042] This aspect provides a suitable configuration example for a compact fundus imaging device that is capable of wide-angle imaging. Also, this aspect reduces the possibility of the device (e.g., an elliptical concave mirror or its housing) hitting the subject's head.

[0043] In some aspects, the first elliptical concave mirror and the second elliptical concave mirror may be arranged so that a plane including the major axis of the first elliptical concave mirror and a plane including the major axis of the second elliptical concave mirror are parallel to each other. For example, the two or more curved mirrors (the two or more elliptical concave mirrors) may be arranged so that two or more focal points of the two or more curved mirrors are located on approximately the same plane (common plane of focal points).

[0044] A ninth aspect of the embodiment is a fundus imaging device of the eighth aspect, in which the first elliptical concave mirror and the second elliptical concave mirror are arranged so that the long axis of the first elliptical concave mirror and the long axis of the second elliptical concave mirror are perpendicular to each other.

[0045] For example, the first elliptical concave mirror may be arranged so that its major axis is parallel to a horizontal plane, and the second elliptical concave mirror may be arranged so that its major axis is perpendicular to the horizontal plane. In other words, the first elliptical concave mirror may be arranged so that its major axis is parallel to a horizontal plane, and the second elliptical concave mirror may be arranged so that its major axis is parallel to a vertical plane.

[0046] This aspect provides a suitable configuration example for a compact fundus imaging device that is capable of wide-angle imaging. Also, this aspect reduces the possibility of the device (e.g., an elliptical concave mirror or its housing) hitting the subject's head.

[0047] A tenth aspect of the embodiment provides a configuration example of an illumination optical system in the fundus imaging device of any one of the first to ninth aspects. The illumination optical system of this aspect further includes a slit member having a slit opening. Illumination light generated by the light source is projected onto the slit member. A portion of the illumination light projected onto the slit member passes through the slit opening and is guided to the optical scanner. The optical scanner deflects the illumination light that has passed through the slit opening. The optical scanner can change the direction in which the illumination light is deflected. The illumination light deflected by the optical scanner is projected onto the fundus of the subject's eye via a first elliptical concave mirror and a second elliptical concave mirror.

[0048] According to this aspect, it is possible to provide a suitable configuration example for a compact fundus imaging device capable of wide-angle imaging. More specifically, in the compact fundus imaging device capable of wide-angle imaging, fundus scanning can be performed using slit-shaped illumination light (slit illumination light).

[0049] In this aspect, the image sensor may be capable of signal readout using a rolling shutter method. In this aspect, control of the optical scanner for deflecting the slit illumination light and control of the image sensor for signal readout using the rolling shutter method can be performed synchronously. This aspect not only enables the fundus imaging device capable of wide-angle imaging to be miniaturized, but also makes it possible to generate high-contrast images with a simple configuration.

[0050] An eleventh aspect of the embodiment is the fundus imaging apparatus of the tenth aspect, wherein the slit member is disposed at an angle with respect to the optical axis of the illumination optical system.

[0051] According to this aspect, it is possible to provide a suitable configuration example for a fundus imaging device that is capable of wide-angle imaging and is compact.

[0052] A twelfth aspect of the embodiment is the fundus imaging apparatus of the tenth or eleventh aspect, further comprising a second focusing mechanism as an element for adjusting the focus of the illumination optical system. The second focusing mechanism moves a slit member, for example, along the optical axis of the illumination optical system (optical axis direction).

[0053] According to this aspect, the focus of the illumination optical system can be adjusted according to the diopter of the subject's eye, etc. This makes it possible to reduce the size of a fundus imaging device capable of wide-angle imaging and also improve image quality.

[0054] Various options that may be employed in some embodiments are described below.

[0055] The fundus imaging device may include both a first focusing mechanism for adjusting the focus of the light receiving optical system and a second focusing mechanism for adjusting the focus of the illumination optical system, and in this aspect, the first focusing mechanism and the second focusing mechanism can be controlled synchronously.

[0056] The fundus photography device illuminates the fundus with slit illumination light so that the longitudinal direction of a slit image (an image of the slit illumination light that has passed through a slit opening) formed by the illumination light projected onto the fundus of the subject's eye is approximately parallel to a plane that includes two or more foci, and moves the slit illumination light in a direction that intersects with the longitudinal direction of the slit image (for example, a direction perpendicular to the longitudinal direction).

[0057] Examples of curved mirrors include ellipsoidal mirrors, parabolic mirrors, hyperbolic mirrors, free-form mirrors, and mirrors whose reflective surfaces are expressed by high-order polynomials. The reflective surface of a curved mirror may be a concave reflective surface or a convex reflective surface. That is, examples of curved mirrors include ellipsoidal concave mirrors, ellipsoidal convex mirrors, parabolic concave mirrors, parabolic convex mirrors, hyperbolic concave mirrors, hyperbolic convex mirrors, free-form mirrors with concave reflective surfaces, free-form surfaces with convex reflective surfaces, concave mirrors whose reflective surfaces are expressed by high-order polynomials, and convex mirrors whose reflective surfaces are expressed by high-order polynomials.

[0058] The focal point of a curved mirror not only refers to a position uniquely determined by the shape of the curved surface, but can also refer to a position where the concentration of light rays (light beams) reflected by the reflective surface is higher than at other positions.

[0059] In the embodiments described below, we will mainly describe a fundus imaging device equipped with two curved mirrors (two elliptical concave mirrors), but the configuration of the fundus imaging device is not limited to this and may be equipped with three or more curved mirrors.

[0060] In the embodiments described below, in accordance with the convention in the field of ophthalmology, the direction along the axis of the subject's eye E is defined as the Z direction (axial direction, Z axis), and the plane perpendicular to the Z direction is defined as the XY plane. The Z direction (Z axis) is also defined as the direction of the optical axis of an optical system that applies illumination light to the subject's eye. The left-right direction (horizontal direction) for the subject is defined as the X direction (X axis), and the direction perpendicular to both the X and Z directions (up-down direction, vertical direction, body axis direction) is defined as the Y direction (Y axis).

[0061] Furthermore, the longitudinal direction of the slit image means, for example, the direction along the long side of the rectangle circumscribing the slit image, and the lateral direction of the slit image means, for example, the direction along the short side of the rectangle.

[0062] The present disclosure describes various non-limiting aspects, including the first to twelfth aspects described above. The present disclosure mainly describes exemplary aspects of fundus imaging devices. However, the categories of aspects of the embodiments are not limited thereto. For example, it will be understood by those skilled in the art that embodiments of the present disclosure can provide various aspects of methods for controlling fundus imaging devices, various aspects of medical methods, various aspects of imaging methods, various aspects of data processing methods, various aspects of programs, various aspects of recording media, and the like.

[0063] <Non-limiting aspects of embodiments> Several non-limiting aspects of a fundus imaging device according to an embodiment will be described. One example of the configuration of the optical system of a fundus imaging device according to an embodiment is shown in Fig. 1. In Fig. 1, a position that is approximately optically conjugate with the fundus Ef of the subject's eye E (fundus conjugate position) is indicated by the symbol P. Furthermore, a position that is approximately optically conjugate with the iris (pupil) of the subject's eye E (iris conjugate position, pupil conjugate position) is indicated by the symbol Q.

[0064] The fundus photographing apparatus 1 of this embodiment includes an illumination optical system 10, a photographing optical system 20, a hole mirror 30 as an optical path splitting member (optical path combining member), and a relay optical system 50.

[0065] The illumination optical system 10 generates illumination light to be projected onto the fundus Ef of the subject's eye E. The illumination optical system 10 of this embodiment generates slit illumination light (illumination light whose light beam cross section is approximately slit-shaped). The generated illumination light is projected onto the hole mirror 30.

[0066] The illumination optical system 10 includes an illumination light source 11, an iris diaphragm 12, a relay lens 13, a slit member 14, a relay lens 15, an optical scanner 16, and a relay lens 17. In some embodiments, the relay lens 13 is made up of one or more lenses. The same applies to the relay lenses 15 and 17.

[0067] The illumination light source 11 generates light in a predetermined wavelength range. For example, the illumination light source 11 includes a visible light source that generates light in the visible range. The visible light source of the illumination light source 11 generates light having a center wavelength in the wavelength range of 420 to 700 nanometers, for example. Such illumination light source 11 includes, for example, any of a light-emitting diode (LED), a laser diode (LD), a halogen lamp, and a xenon lamp. In some aspects, the illumination light source 11 includes a white light source and / or a light source capable of outputting light of each color component of RGB. In some aspects, the illumination light source 11 includes an infrared light source that generates light in the infrared range. In some aspects, the illumination light source 11 includes a light source that can output light in the infrared range and light in the visible range selectively or simultaneously.

[0068] An opening is formed in the iris diaphragm 12. The iris diaphragm 12 (opening) can be placed at an iris conjugate position Q, which is a position optically conjugate with the iris (pupil) of the subject's eye E or a position close to the position. The iris diaphragm 12 has one or more openings formed at positions away from the optical axis of the optical path of light output from the illumination light source 11. The opening of the iris diaphragm 12 defines the incident position (incident shape) of the illumination light on the iris (pupil) of the subject's eye E.

[0069] In some embodiments, the relative position between the illumination light source 11 and the opening of the iris diaphragm 12 can be changed, thereby changing the light intensity distribution of the light passing through the opening of the iris diaphragm 12.

[0070] In some aspects, the illumination light source 11 has the function of the iris diaphragm 12. In such aspects, an iris diaphragm member (a member that realizes the function of the iris diaphragm 12) provided in the illumination light source 11 is disposed at the iris conjugate position Q.

[0071] An opening (slit opening) is formed in the slit member 14. The slit member 14 (slit opening) can be placed at a position optically conjugate with the fundus Ef of the subject's eye E or at a fundus conjugate position P, which is a position nearby the fundus Ef. The slit opening of the slit member 14 defines the shape of the projection area of ​​the illumination light on the fundus Ef of the subject's eye E (the slit image projected on the fundus Ef). The illumination light emitted from the illumination light source 11 is projected onto the slit member 14, and a portion of it passes through the slit opening. This generates slit illumination light whose beam cross section is formed in a substantially slit shape.

[0072] The slit member 14 can be moved by a moving mechanism (specifically, a moving mechanism 14D described later) not shown in the figure in a direction along the optical axis of the illumination optical system 10. This allows the slit member 14 to be moved to a position according to the condition of the subject's eye E (specifically, the diopter (refractive power), axial length, shape of the fundus Ef, etc.).

[0073] In some aspects, the position and / or shape of the slit opening can be changed instead of or in addition to moving the slit member 14. This function is realized by, for example, a liquid crystal shutter.

[0074] The optical scanner 16 has a surface (deflection surface) that deflects the illumination light. The optical scanner 16 (deflection surface) can be placed at a position optically conjugate with the iris (pupil) of the subject's eye E or at an iris conjugate position Q, which is a position nearby the iris conjugate position. The optical scanner 16 is, for example, a uniaxial optical scanner configured to be able to change the orientation of the deflection surface in a predetermined direction. The optical scanner 16 one-dimensionally deflects the slit illumination light generated by the slit member 14. For example, the optical scanner 16 deflects the slit illumination light so that the slit image projected on the fundus Ef moves in a direction intersecting its longitudinal direction (typically, a direction perpendicular to the longitudinal direction). The moving direction of the slit image is called the scanning direction.

[0075] The optical scanner 16 may be any device capable of changing the traveling direction of light, and may include, for example, a galvanometer scanner, a microelectromechanical system (MEMS) scanner, a polygon mirror, or a resonant scanner. For example, the optical scanner 16 includes a galvanometer scanner that deflects the illumination light within a predetermined deflection angle range based on a predetermined deflection direction.

[0076] In some embodiments, the optical scanner 16 may be a biaxial optical scanner capable of two-dimensionally deflecting the slit illumination light. For example, the optical scanner 16 includes a first scanner and a second scanner. The first scanner deflects the slit illumination light so as to move the slit image on the fundus Ef in a horizontal direction (X direction) perpendicular to the optical axis of the illumination optical system 10. The second scanner deflects the slit illumination light so as to move the slit image on the fundus Ef in a vertical direction (Y direction) perpendicular to the optical axis of the illumination optical system 10. Either the first scanner or the second scanner may be disposed on the illumination light source 11 side.

[0077] According to the illumination optical system 10 of this embodiment, illumination light emitted by the illumination light source 11 is first projected onto the iris diaphragm 12. A portion of the illumination light that passes through the opening of the iris diaphragm 12 is relayed by the relay lens 13 and projected onto the slit member 14. A portion of the illumination light that passes through the slit opening of the slit member 14 is used as slit illumination light. The generated slit illumination light is relayed by the relay lens 15 and projected onto the polarization plane of the optical scanner 16. The slit illumination light deflected by the optical scanner 16 is relayed by the relay lens 17 and guided to the hole mirror 30.

[0078] In some embodiments, the illumination optical system 10 includes a projector equipped with a light source, and the projector generates slit illumination light. In such embodiments, the projector is provided instead of the illumination light source 11, the iris diaphragm 12, the relay lens 13, and the slit member 14 shown in FIG. 1. Examples of projectors that can be used in the illumination optical system 10 include a liquid crystal display (LCD) projector using a transmissive liquid crystal panel, a liquid crystal on silicon (LCOS) projector using a reflective liquid crystal panel, and a digital light processing (DLP) (registered trademark) projector using a digital mirror device (DMD).

[0079] The hole mirror 30 has a light reflecting surface and an opening (hole portion) formed in this light reflecting surface. The hole mirror 30 (opening) can be arranged at the iris conjugate position Q. The hole mirror 30 functions as an optical path splitting member that spatially splits the optical path of the illumination light and the optical path of the return light from the subject's eye E onto which the illumination light is projected. The hole mirror 30 can also be considered as an optical path combining member that combines the optical path of the illumination light and the optical path of the return light.

[0080] The hole mirror 30 has a hole formed in the center of its base, through which the optical axis passes, and a light-reflecting surface is provided around the center (periphery). In the optical system of Fig. 1, the hole mirror 30 is positioned so that the optical axis of the photographing optical system 20 passes through the hole. In the optical system of Fig. 1, illumination light provided from the illumination optical system 10 is reflected by the light-reflecting surface in the periphery of the hole mirror 30 and is guided to the relay optical system 50.

[0081] The configuration of the optical system using the hole mirror 30 is not limited to that shown in FIG. 1 . In some embodiments, the hole mirror 30 is arranged so that the optical axis of the illumination optical system 10 passes through a hole in the center, and the return light of the illumination light from the subject's eye E is reflected by a reflective surface in the peripheral portion and directed to the imaging optical system 20. In some embodiments, the hole mirror 30 has a hole formed on one side of the base through which the optical axis passes, and a light-reflecting surface is provided on the other side of the base. In this case, light passing through the hole is directed to the imaging optical system 20, and light reflected by the light-reflecting surface is directed to the subject's eye E. Alternatively, conversely, light passing through the hole is directed to the subject's eye E, and light reflected by the light-reflecting surface is directed to the imaging optical system 20.

[0082] Illumination light from the illumination optical system 10 is reflected by the reflecting surface around the hole formed in the hole mirror 30 and is guided to the relay optical system 50. Return light from the subject's eye E is guided by the relay optical system 50 to the hole mirror 30, passes through the hole in the hole mirror 30, and is guided to the photographing optical system 20.

[0083] The optical element that can be used as the optical path splitting member that has the function of splitting the optical path of the illumination light into the optical path of the return light is not limited to the hole mirror 30. In some aspects, instead of the hole mirror 30, any of a beam splitter, a half mirror, a polygonal mirror, and a dichroic mirror may be used.

[0084] The photographing optical system 20 functions as a light-receiving optical system that detects, via the relay optical system 50, return light of the illumination light projected onto the fundus Ef of the subject's eye E. The photographing optical system 20 in Fig. 1 detects return light from the subject's eye E that has passed through the hole in the hole mirror 30. The return light from the subject's eye E includes reflected light (particularly, light reflected by the fundus Ef) and scattered light of the illumination light that has entered the subject's eye E. In some embodiments, the return light from the subject's eye E includes, in addition to reflected light and scattered light of the illumination light that has entered the subject's eye E, fluorescence whose excitation light is the illumination light that has entered the subject's eye E and its scattered light.

[0085] The photographing optical system 20 includes an image sensor 21, a lens group 22, and a lens group 23. The lens group 22 is made up of one lens or a combination of two or more lenses. Similarly, the lens group 23 is made up of one lens or a combination of two or more lenses.

[0086] The lens group 22 and the lens group 23 are disposed eccentrically relative to each other. That is, the optical axis of the lens group 22 and the optical axis of the lens group 23 are disposed parallel to each other and are not disposed on the same straight line.

[0087] The image sensor 21 is a two-dimensional image sensor that functions as a pixelated light receiver. The light receiving surface (light detection surface) of the image sensor 21 can be placed at a fundus conjugate position P. The image sensor 21 can set a virtually movable light receiving area (light receiving area) at the fundus conjugate position P.

[0088] For example, the light reception results by the image sensor 21 are captured and read out using a rolling shutter method. In some aspects, the light reception results by the image sensor 21 are captured and read out using a global shutter method in which the light reception area is changeable or movable. The image sensor 21 is controlled by the control unit 60, which will be described later, to read out the light reception results. In some aspects, the image sensor 21 can automatically output the light reception results for a predetermined line together with information indicating the light reception position.

[0089] Such an image sensor 21 includes, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor. In this case, the image sensor 21 includes a plurality of pixel (light receiving element) groups arranged in the row direction, and each pixel group includes a plurality of pixels arranged in the column direction. That is, in this case, the image sensor 21 includes a plurality of pixels arranged two-dimensionally, a plurality of vertical signal lines, and a plurality of horizontal signal lines.

[0090] In some embodiments, image sensor 21 includes, for example, a charge coupled device (CCD) image sensor.

[0091] By capturing (reading out) the light reception results from the image sensor 21 using the rolling shutter method, an image in a light-receiving area corresponding to a desired virtual opening shape extending in the row direction is obtained. Readout control using the rolling shutter method is well known, and details thereof are described in, for example, Patent Document 3 and U.S. Patent No. 8,237,835.

[0092] Return light from the subject's eye E onto which illumination light from the illumination optical system 10 is projected passes through the hole in the hole mirror 30 and is imaged on the light receiving surface of the image sensor 21 by the lens group 23 and the lens group 22 .

[0093] The image sensor 21 and the lens group 22 can be moved integrally by a moving mechanism (specifically, a moving mechanism 20D described later) not shown in the figure in a direction along the optical axis of the photographing optical system 20. As a result, by moving the image sensor 21 and the lens group 22 to a position according to the state of the subject's eye E (specifically, the diopter (refractive power), the axial length, the shape of the fundus Ef, etc.), it is possible to form an image of the returning light from the subject's eye E on the light receiving surface of the image sensor 21.

[0094] In some aspects, the position of the image sensor 21 is fixed, and the lens group 22 is movable by a moving mechanism in a direction along the optical axis of the photographing optical system 20. In some aspects, the positions of the image sensor 21 and the lens group 22 are fixed, and the lens group 23 is movable by a moving mechanism in a direction along the optical axis of the photographing optical system 20. In some aspects, the position of the image sensor 21 is fixed, and the lens group 22 and the lens group 23 are movable by a moving mechanism in a direction along the optical axis of the photographing optical system 20. In any aspect, it is possible to receive returned light that is suited to the state of the subject's eye E.

[0095] In some embodiments, one or more relay lenses may be disposed between the hole mirror 30 and the lens group 23, between the lens group 23 and the lens group 22, or between the lens group 22 and the image sensor 21. Also, one or more relay lenses may be disposed between the hole mirror 30 and the relay optical system 50.

[0096] The relay optical system 50 is disposed between the hole mirror 30 and the subject's eye E. The relay optical system 50 relays a slit image formed by the slit illumination light generated by the illumination optical system 10 to the fundus Ef of the subject's eye E. The relay optical system 50 includes a reflective optical system having an angle-of-view expansion function. In this case, the relay optical system 50 may further include a refractive optical system such as an aberration correction lens. In some aspects, the relay optical system 50 does not need to have an angle-of-view expansion function.

[0097] One specific example of the optical system of FIG. 1 is shown in FIG. 2. FIG. 2 shows a view from above (XZ plane view, top view) and a view from the side (YZ plane view, side view). The XZ plane view is the part surrounded by a dashed line, and the YZ plane view is the part surrounded by a dashed line. In FIG. 2, elements that are the same as those in FIG. 1 are given the same reference numerals. Unless otherwise specified, explanations of elements that are the same as those in FIG. 1 will be omitted.

[0098] 2, the illumination light source 11 of the illumination optical system 10 includes three light sources, lens groups arranged on optical paths originating from each light source, two optical path combining members for combining the three optical paths originating from the three light sources, and a lens group arranged on an optical path combining these three optical paths. The three light sources generate illumination light with different characteristics.

[0099] Illumination light generated by each light source of the illumination light source 11 is guided to the slit member 14 via a group of lenses arranged in a composite optical path, an iris diaphragm 12, and a relay lens 13 consisting of a group of lenses. In this example, the slit member 14 is tilted with respect to the optical axis of the illumination optical system 10, as shown in the XZ plane view. The illumination light (slit illumination light) that passes through the slit opening of the slit member 14 is guided to the optical scanner 16 via a relay lens 15. The optical scanner 16 can rotate its light deflection plane in the direction indicated by the bidirectional arrow in the YZ plane view. The slit illumination light deflected by the optical scanner 16 is guided to the hole mirror 30 via a relay lens 17. The slit illumination light is reflected by the hole mirror 30 and enters the relay optical system 50. In another embodiment, the slit illumination light passes through a hole in the hole mirror 30 and enters the relay optical system 50.

[0100] As shown in the XZ plane view, the relay optical system 50 includes a first elliptical concave mirror 51 and a second elliptical concave mirror 52 .

[0101] The light-reflecting surface of the first elliptical concave mirror 51 is a concave ellipsoid. The first elliptical concave mirror 51 is an example of a curved mirror or a concave mirror. The first elliptical concave mirror 51 has two optically conjugate focal points (a first focal point F1 and a second focal point F2). The hole of the hole mirror 30 is located at or near the first focal point F1, and can be located at the iris conjugate position (pupil conjugate position) Q as described above.

[0102] The light reflecting surface of the second elliptical concave mirror 52 is a concave ellipsoid. The second elliptical concave mirror 52 is an example of a curved mirror or a concave mirror. The second elliptical concave mirror 52 has two optically conjugate focal points (a first focal point F3 and a second focal point F4).

[0103] The first elliptical concave mirror 51 and the second elliptical concave mirror 52 share one focus. That is, the first focus F3 of the second elliptical concave mirror 52 is located at the same position as or near the second focus F2 of the first elliptical concave mirror 51. In some aspects, the first focus F3 of the second elliptical concave mirror 52 may be located at a position optically conjugate to the second focus F2 of the first elliptical concave mirror 51 (a conjugate position of the second focus F2) or at a position nearby.

[0104] When photographing the fundus Ef of the subject's eye E, the subject's eye E (iris, pupil) is positioned at the second focal point F4 of the second elliptical concave mirror 52 or a position in the vicinity thereof.

[0105] In some embodiments, the first elliptical concave mirror 51 and the second elliptical concave mirror 52 may be arranged so that the two foci of the first elliptical concave mirror 51 (first focus F1, second focus F2) and the two foci of the second elliptical concave mirror 52 (first focus F3, second focus F4) are located in the same plane (focal point shared plane).

[0106] 3, the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are oriented and arranged so that the major axis 51a of the first elliptical concave mirror 51 and the major axis 52a of the second elliptical concave mirror 52 are both included in the horizontal plane (XY plane). The symbol H indicates the subject's head. In this example, the second elliptical concave mirror 52, which is arranged immediately in front of the subject's eye E, is large enough to cover the subject's eye and part of the nose. The first elliptical concave mirror 51 also has a similar size.

[0107] In contrast, in some embodiments, the first elliptical concave mirror 51 and the second elliptical concave mirror 52 may be arranged so that the plane containing the long axis 51a of the first elliptical concave mirror 51 and the plane containing the long axis 52a of the second elliptical concave mirror 52 are non-parallel to each other.

[0108] One example is shown in Fig. 4. In this example, the second elliptical concave mirror 52 is oriented and disposed so that its major axis 52a is contained within a horizontal plane (XY plane), and the first elliptical concave mirror 51 is oriented and disposed so that the X-, Y-, and Z-direction components of the vector indicating the direction of its major axis 51a are all non-zero. In this example, the size of the second elliptical concave mirror 52 disposed immediately in front of the subject's eye E is large enough to cover the subject's eye and part of the nose, and the size of the first elliptical concave mirror 51 is also approximately the same.

[0109] Another example is shown in Fig. 5. In this example, the second elliptical concave mirror 52 is oriented and disposed so that its major axis 52a is included in a horizontal plane (XY plane), and the first elliptical concave mirror 51 is oriented and disposed so that its major axis 51a is included in a vertical plane (YZ plane). In this example, the size of the second elliptical concave mirror 52 disposed immediately in front of the subject's eye E is large enough to cover the subject's eye and part of the nose, and the size of the first elliptical concave mirror 51 is also approximately the same.

[0110] In the above-described configuration, the slit illumination light from the illumination optical system 10 enters the relay optical system 50 via the hole mirror 30 disposed at the first focus F1 of the first elliptical concave mirror 51, is reflected by the reflecting surface of the first elliptical concave mirror 51, and is directed to the second focus F2 of the first elliptical concave mirror 51. The second focus F2 of the first elliptical concave mirror 51 is located at the same position as the first focus F3 of the second elliptical concave mirror 52. The slit illumination light directed to the first focus F3 of the second elliptical concave mirror 52 is reflected by the reflecting surface of the second elliptical concave mirror 52, and is directed to the subject's eye E disposed at the second focus F4 of the second elliptical concave mirror 52.

[0111] The slit illumination light guided to the subject's eye E passes through the cornea, anterior chamber, pupil, crystalline lens, and vitreous body and is projected onto the fundus Ef. Fundus reflection light of the slit illumination light passes through the vitreous body, crystalline lens, pupil, anterior chamber, and cornea and is emitted from the subject's eye E. Return light from the subject's eye E, including fundus reflection light of the slit illumination light, travels in the opposite direction along the same path as the slit illumination light and is guided to the first focal point F1 of the first elliptical concave mirror 51, passes through the hole in the hole mirror 30 located at the first focal point F1, and is guided to the photographing optical system 20.

[0112] The photographic optical system 20 in Fig. 2 includes three lens groups 22a, 22b, and 23. The combination of the two lens groups 22a and 22b corresponds to the lens group 22 in Fig. 1. Return light incident on the photographic optical system 20 passes through the lens group 23, the lens group 22b, and the lens group 22a in this order before being guided to the image sensor 21. The lens group 22b is disposed eccentrically with respect to the lens group 23, and the lens group 22a is disposed eccentrically with respect to the lens group 22b. Here, the lens group 22a is disposed eccentrically with respect to both the lens group 22b and the lens group 23.

[0113] 2, the decentering direction of the lens group 22b relative to the lens group 23 shown in the XZ plan view is the same as the decentering direction of the lens group 22a relative to the lens group 22b, and the decentering direction of the lens group 22b relative to the lens group 23 shown in the YZ plan view is the same as the decentering direction of the lens group 22a relative to the lens group 22b. In other words, the lens group 23, the lens group 22b, and the lens group 22a are arranged to be decentered in stages in the same direction.

[0114] 2, the image sensor 21 is disposed at an angle with respect to the optical axis of the lens group 23, the optical axis of the lens group 22b, and the optical axis of the lens group 22a. The light-receiving surface of the image sensor 21 detects the returned light, and the detection result of the returned light in a light-receiving area set on the light-receiving surface is captured.

[0115] The fundus imaging device 1 may be provided with a configuration for providing functions associated with the examination. For example, the fundus imaging device 1 may be provided with a fixation optical system for projecting a visual target (fixation target) for fixating the subject's eye E onto the fundus Ef of the subject's eye E. The fundus imaging device 1 may also be provided with an alignment optical system for aligning the subject's eye E with the optical system. The fundus imaging device 1 may also be provided with any selected element or unit, such as a member for supporting or holding the subject's face (such as a chin rest or forehead rest).

[0116] The fundus imaging device 1 is capable of adjusting the focus of the illumination optical system 10 by moving the slit member 14, and adjusting the focus of the imaging optical system 20 by moving the lens group 22 and the image sensor 21 (or the lens group 22). The configuration for performing the focus adjustment is not limited to these. In some aspects, the fundus imaging device is configured to perform the focus adjustment by moving an optical system unit (a unit including the illumination optical system 10, the imaging optical system 20, and the hole mirror 30, or a unit including the illumination optical system 10, the imaging optical system 20, the hole mirror 30, the first elliptical concave mirror 51, and the second elliptical concave mirror 52) using a moving mechanism (not shown).

[0117] Next, the processing system of the fundus imaging apparatus 1 according to the embodiment will be described. An example of the configuration of the processing system is shown in Fig. 6. In Fig. 6, the same elements as those in Figs. 1 and 2 are given the same reference numerals. Unless otherwise specified, the description of the same elements as those in Figs. 1 and 2 will be omitted.

[0118] The processing system of the fundus imaging device 1 is mainly configured with a control unit 60. The control unit 60 controls each unit of the fundus imaging device 1.

[0119] The control unit 60 includes a main control unit 61 and a storage unit 62. The functions of the main control unit 61 are realized by, for example, a processor. The storage unit 62 stores in advance computer programs for controlling the fundus imaging device 1. These computer programs include an illumination light source control program, an image sensor control program, an optical scanner control program, an image construction program, a user interface program, and a data communication program. The main control unit 61 operates in accordance with these computer programs, causing the control unit 60 to execute various control processes.

[0120] The main control unit 61 controls the illumination optical system 10 , the photographing optical system 20 , the image construction unit 70 , the user interface (UI) unit 80 , and the communication unit 90 .

[0121] The control of the illumination optical system 10 includes control of the illumination light source 11, control of the moving mechanism 14D, control of the optical scanner 16, and the like.

[0122] Control of the illumination light source 11 includes turning the light source on and off, adjusting the light intensity, switching wavelengths, adjusting the aperture, and the like.

[0123] The moving mechanism 14D moves the slit member 14 in a direction along the optical axis of the illumination optical system 10. The main control unit 61 outputs a control signal to the moving mechanism 14D, thereby moving the slit member 14 in a direction corresponding to the control signal and by a movement amount (movement distance) corresponding to the control signal. For example, the moving mechanism 14D includes an actuator that generates a driving force for moving the slit member 14 and a transmission mechanism that transmits this driving force. The actuator may be, for example, a pulse motor. The transmission mechanism is configured, for example, by a combination of gears or a rack and pinion. The moving mechanism 14D moves the slit member 14 by transmitting the driving force generated by the operation of the actuator under the control of the main control unit 61 to the slit member 14 via the transmission mechanism.

[0124] Control of the optical scanner 16 includes control of the orientation (angle) of the deflection surface onto which the illumination light is projected. By changing the orientation of the deflection surface, the deflection direction (scanning direction) of the illumination light changes. By controlling the range (angular range) within which the orientation of the deflection surface changes, the scanning range (scan start position and scan end position) is controlled. By controlling the speed at which the orientation of the deflection surface is changed, the scanning speed is controlled.

[0125] The control of the photographing optical system 20 includes control of the image sensor 21 and control of the moving mechanism 20D.

[0126] Control of the image sensor 21 includes setting control of the light-receiving area on the light-receiving surface, and control for reading out the light-receiving results using a rolling shutter method (for example, setting the light-receiving size corresponding to the size of the illumination pattern). Control of the image sensor 21 also includes reset control, exposure control, charge transfer control, output control, etc.

[0127] The moving mechanism 20D moves at least a part of the photographing optical system 20. For example, the moving mechanism 20D moves the image sensor 21 and the lens group 22 (lens groups 22a and 22b) in a direction along the optical axis of the photographing optical system 20. In another example, the moving mechanism 20D moves the lens group 22 (lens groups 22a and 22b) in a direction along the optical axis of the photographing optical system 20. The main control unit 61 outputs a control signal to the moving mechanism 20D, thereby moving the image sensor 21 and the lens group 22 (or the lens group 22) in a movement direction corresponding to the control signal and by a movement amount (movement distance) corresponding to the control signal. The configuration of the moving mechanism 20D may be similar to that of the moving mechanism 14D.

[0128] The control over the image construction unit 70 includes image construction control for constructing an image of the subject's eye E from the light reception results obtained by the image sensor 21 .

[0129] The control over the user interface unit 80 includes control over the display device, control over the operation device (input device), and the like.

[0130] The control over the communication unit 90 includes control for transmitting data to an external device, control for receiving data from an external device, control for encryption processing, control for decryption processing, and the like.

[0131] The storage unit 62 stores various types of data. Examples of the data stored in the storage unit 62 include the light reception results obtained by the image sensor 21, the image generated by the image construction unit 70, parameters related to image processing such as image distortion correction, and information about the subject's eye. The information about the subject's eye includes information about the subject, such as the patient ID and name, and information about the subject's eye, such as identification information for the left eye or right eye.

[0132] The storage unit 62 also stores various programs and data for operating the fundus imaging apparatus 1 .

[0133] The image constructing unit 70 can construct a light-receiving image (fundus image) corresponding to any light-receiving area based on the light-receiving results read out from the image sensor 21 by the rolling shutter method. The image constructing unit 70 sequentially constructs light-receiving images corresponding to the light-receiving area, and constructs an image of the subject's eye E (fundus Ef) from the multiple light-receiving images thus obtained. The image generated by the image constructing unit 70 is stored in the storage unit 62 or another storage device.

[0134] The image construction unit 70 includes a processor and operates in accordance with a program stored in the storage unit 62 or another storage device to execute the image construction process.

[0135] The image constructing unit 70 may be capable of executing a process of correcting distortion of the generated image (image distortion correction). The image distortion correction uses at least one of a preset distortion correction parameter and a distortion correction parameter that is set based on the degree of distortion of the image to be corrected.

[0136] For example, the image constructor 70 may be configured to correct distortion in the original image by correcting pixel positions within one or more polygonal regions in the original image so that each of the regions becomes a region of a predetermined shape. In some embodiments, the image constructor 70 may be configured to selectively apply image distortion correction only to predetermined correction regions.

[0137] The user interface unit 80 has a function for exchanging information and instructions between the user and the fundus imaging apparatus 1. The user interface unit 80 includes a display device and an operation device. The user interface unit 80 may include a device (e.g., a touch panel display) that integrates at least some of the functions of the display device and at least some of the functions of the operation device.

[0138] The display device may include a display unit that is an element of the fundus imaging apparatus 1, or may include a display device that is a peripheral device of the fundus imaging apparatus 1. The display device visually presents information under the control of the main control unit 61. The display device includes, for example, a liquid crystal display.

[0139] The operation device includes one or more hardware keys and / or one or more software keys. The operation device may include an operation unit that is an element of the fundus imaging apparatus 1, or may include an operation device that is a peripheral device of the fundus imaging apparatus 1. The operation device generates an electrical signal corresponding to the content of an operation instruction given using the operation device and sends it to the main control unit 61. The main control unit 61 receives the electrical signal from the operation device, generates a control signal corresponding to the content of the operation instruction, and sends it to the element to be controlled.

[0140] The communication unit 90 performs data communication between the fundus imaging device 1 and other devices. That is, the communication unit 90 transmits data to other devices and receives data transmitted from other devices. The communication unit 90 may perform any data communication method. For example, the communication unit 90 may include one or more of various communication interfaces, such as a communication interface compatible with the Internet, a communication interface compatible with a dedicated line, a communication interface compatible with a LAN, and a communication interface compatible with short-range communication. Data communication may be wired communication or wireless communication.

[0141] The data transmitted or received by the communication unit 90 may be encrypted data. In this case, the control unit 60 and / or the communication unit 90 may include an encryption processing unit that encrypts the data transmitted by the communication unit 90 and a decryption processing unit that decrypts the data received by the communication unit 90.

[0142] The following describes some of the functions of the fundus imaging apparatus 1 according to the embodiment, as well as some of the advantages achieved by the fundus imaging apparatus 1 according to the embodiment.

[0143] The fundus imaging device 1 is a device for imaging the fundus Ef of the subject's eye E, and includes an illumination optical system 10, an imaging optical system 20, and a relay optical system 50. The illumination optical system 10 includes an illumination light source 11 that generates illumination light, an optical scanner 16 that deflects the illumination light generated by the illumination light source 11, and the like.

[0144] The relay optical system 50 includes a first elliptical concave mirror 51 and a second elliptical concave mirror 52. The first elliptical concave mirror 51 is an example of a first curved mirror, and reflects the illumination light from the illumination optical system 10. The second elliptical concave mirror 52 is an example of a second curved mirror, and reflects the illumination light reflected by the first elliptical concave mirror 51 and guides it to the eye E to be examined.

[0145] The light-reflecting surface of the first elliptical concave mirror 51 has an ellipsoidal shape and therefore has two foci (first focus F1 and second focus F2). Similarly, the light-reflecting surface of the second elliptical concave mirror 52 has an ellipsoidal shape and therefore has two foci (first focus F3 and second focus F4). The first elliptical concave mirror 51 and the second elliptical concave mirror 52 share one focus (second focus F2 and first focus F3). In other words, the spatial position of the second focus F2 and the spatial position of the first focus F3 are approximately the same.

[0146] The light reflecting surface of the first elliptical concave mirror 51 is formed to have a pre-designed curvature distribution, and the light reflecting surface of the second elliptical concave mirror 52 is formed to have a pre-designed curvature distribution. The curvature distributions of the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are different from each other.

[0147] For example, the light-reflecting surface of the first elliptical concave mirror 51 may be part of an ellipsoid whose major axis value falls within the range of 60 to 90 millimeters and whose minor axis value falls within the range of 40 to 70 millimeters. Similarly, the light-reflecting surface of the second elliptical concave mirror 52 may be part of an ellipsoid whose major axis value falls within the range of 60 to 90 millimeters and whose minor axis value falls within the range of 40 to 70 millimeters.

[0148] More specifically, the light-reflecting surface of the first elliptical concave mirror 51 may be part of an ellipsoid whose major axis value falls within the range of 70 to 80 mm and whose minor axis value falls within the range of 50 to 60 mm. Similarly, the light-reflecting surface of the second elliptical concave mirror 52 may be part of an ellipsoid whose major axis value falls within the range of 70 to 80 mm and whose minor axis value falls within the range of 50 to 60 mm.

[0149] In one example actually realized by the inventors, the light-reflecting surface of the first elliptical concave mirror 51 was designed as part of an ellipsoid with a major axis of 75 mm and a minor axis of 50 mm, and the light-reflecting surface of the second elliptical concave mirror 52 was designed as part of an ellipsoid with a major axis of 72 mm and a minor axis of 60 mm. The magnitude of the deflection angle of the illumination light incident on the relay optical system 50 in this example (i.e., the deflection angle range of the illumination light deflected by the optical scanner 16 at the first focal point F1) was 50 degrees, and the magnitude of the deflection angle of the illumination light exiting the relay optical system 50 in this example (i.e., the deflection angle range of the illumination light at the second focal point F4) was 150 degrees. Therefore, the relay optical system 50 in this example acts to expand the deflection angle of the illumination light by three times, making it possible to photograph the fundus Ef of the subject's eye E at a wide angle of view (150 degrees).

[0150] The photographing optical system 20 is configured to detect return light of illumination light projected onto the fundus Ef of the subject's eye E via a second elliptical concave mirror 52 and a first elliptical concave mirror 51, and is an example of a light-receiving optical system. The photographing optical system 20 includes a lens group 23, a second lens group 22, an image sensor 21, etc. The lens group 23 and the lens group 22 are disposed eccentrically relative to each other. The image sensor 21 detects return light that has passed through the lens group 23 and the lens group 22. The lens group 23 is an example of a first lens group, and the lens group 22 is an example of a second lens group.

[0151] With the fundus imaging device 1 configured in this manner, fundus imaging with a wide angle of view is possible by scanning the fundus Ef using an optical system including a first elliptical concave mirror 51 and a second elliptical concave mirror 52.

[0152] Furthermore, the fundus imaging device 1 employs a configuration in which return light of the illumination light is detected using the imaging optical system 20 including the lens group 23 and the lens group 22 that are disposed eccentrically with respect to each other, thereby making it possible to use the first elliptical concave mirror 51 and the second elliptical concave mirror 52 that are smaller in size than conventional devices. In other words, a fundus imaging device 1 equipped with a curved mirror that is smaller than conventional devices has been realized. Therefore, the technology according to this embodiment makes it possible to miniaturize a fundus imaging device capable of wide-angle imaging.

[0153] In the fundus imaging device 1 according to the embodiment, the image sensor 21 (specifically, the light receiving surface) of the imaging optical system 20 is disposed in an inclined position with respect to both the optical axis of the lens group 23 and the optical axis of the lens group 22. The orientation of the image sensor 21 can be determined using optical design techniques such as ray tracing.

[0154] In this way, by combining the lens group 23 and lens group 22, which are disposed eccentrically with respect to each other, with the tilted image sensor 21, it is possible to suppress asymmetric aberrations that occur when the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are made smaller. Therefore, it is possible to reduce the size of a fundus imaging device capable of wide-angle imaging, and also to improve image quality.

[0155] In a non-limiting aspect of the fundus imaging apparatus 1 according to the embodiment, the lens group 22 of the imaging optical system 20 includes two lens groups 22a and 22b. The three lens groups 23, 22b, and 22a in this aspect are arranged eccentrically relative to one another. Thus, the imaging optical system 20 in this aspect includes the lens group 23 corresponding to the first lens group, the lens group 22b corresponding to the second lens group, the lens group 22a corresponding to the third lens group, and the image sensor 21. The image sensor 21 detects returned light that has passed through the lens group 23, the lens group 22b, and the lens group 22a in this order.

[0156] According to this aspect, it is possible to provide an example of a configuration for detecting return light of illumination light using the photographing optical system 20 including three lens groups 23, 22b, and 22a that are arranged eccentrically with respect to one another. This makes it possible to use the first elliptical concave mirror 51 and the second elliptical concave mirror 52 that are smaller than conventional mirrors, thereby enabling the miniaturization of the fundus photographing device 1 that is capable of photographing at a wide angle of view.

[0157] In a non-limiting aspect of the fundus imaging device 1 according to the embodiment, the image sensor 21 is arranged at an angle relative to the optical axis of the lens group 23, the optical axis of the lens group 22b, and the optical axis of the lens group 22a.

[0158] According to this aspect, by combining the three lens groups 23, 22b, and 22a that are disposed eccentrically with respect to one another with the tilted image sensor 21, it is possible to suppress asymmetric aberration that occurs when the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are made smaller. Therefore, it is possible to reduce the size of a fundus imaging device that is capable of wide-angle imaging, and also to improve image quality.

[0159] In a non-limiting aspect of the fundus imaging apparatus 1 according to the embodiment, return light of illumination light applied to the subject's eye E passes through the lens group 23, the lens group 22b, and the lens group 22a in this order before being guided to the image sensor 21. The fundus imaging apparatus 1 of this embodiment also includes a moving mechanism 20D for adjusting the focus of the imaging optical system 20. The moving mechanism 20D moves at least some elements of the imaging optical system 20 in a direction along the optical axis of the imaging optical system 20 (the optical axis direction). For example, the moving mechanism 20D has a configuration for moving the lens group 22b, the lens group 22a, and the image sensor 21 integrally or individually, a configuration for moving the lens group 22b and the lens group 22a integrally or individually, a configuration for moving the lens group 22b, or a configuration for moving the lens group 22a. The moving mechanism 20D can function as an example of a first focusing mechanism.

[0160] According to this aspect, the focus of the photographing optical system 20 can be adjusted according to the diopter of the subject's eye E. This allows the fundus photographing device 1 capable of photographing at a wide angle of view to be miniaturized, and also allows for improved image quality.

[0161] In the fundus imaging device 1 according to the embodiment, the relative positional relationship between the first elliptical concave mirror 51 and the second elliptical concave mirror 52 may be designed arbitrarily. In some non-limiting aspects, the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are arranged so that a plane including the major axis 51 a of the first elliptical concave mirror 51 and a plane including the major axis 52 a of the second elliptical concave mirror 52 are parallel to each other. For example, the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are oriented and arranged so that both the major axis 51 a of the first elliptical concave mirror 51 and the major axis 52 a of the second elliptical concave mirror 52 are included in a horizontal plane (XY plane) (see FIG. 3 ).

[0162] In some non-limiting aspects, the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are arranged so that a plane including the major axis 51 a of the first elliptical concave mirror 51 and a plane including the major axis 52 a of the second elliptical concave mirror 52 are non-parallel to each other. For example, the second elliptical concave mirror 52 is arranged and oriented so that its major axis 52 a is included in a horizontal plane (XY plane), and the first elliptical concave mirror 51 is arranged and oriented so that the X-direction component, Y-direction component, and Z-direction component of the vector indicating the orientation of its major axis 51 a are all non-zero vectors (see FIG. 4 ).

[0163] In some non-limiting aspects, the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are arranged so that a plane including the major axis 51 a of the first elliptical concave mirror 51 and a plane including the major axis 52 a of the second elliptical concave mirror 52 are perpendicular to each other. For example, the second elliptical concave mirror 52 is oriented so that its major axis 52 a is included in a horizontal plane (XY plane), and the first elliptical concave mirror 51 is oriented so that its major axis 51 a is included in a vertical plane (YZ plane) (see FIG. 5 ).

[0164] According to the example of Figure 4, the example of Figure 5, or similar examples, the possibility of the elliptical concave mirror (particularly the first elliptical concave mirror 51) or its housing colliding with the subject's head H can be reduced.

[0165] In a non-limiting aspect of the fundus imaging apparatus 1 according to the embodiment, the illumination optical system 10 includes a slit member 14 having a slit opening. Furthermore, illumination light generated by the illumination light source 11 is projected onto the slit member 14. The optical scanner 16 deflects the illumination light (slit illumination light) that has passed through the slit opening.

[0166] According to this aspect, it is possible to provide a compact fundus imaging device capable of wide-angle imaging using slit illumination light. In this aspect, the image sensor 21 may be capable of signal readout using a rolling shutter method. This not only enables the compact fundus imaging device capable of wide-angle imaging, but also makes it possible to generate high-contrast images with a simple configuration.

[0167] In a non-limiting aspect of the fundus imaging apparatus 1 according to the embodiment, the slit member 14 is disposed in an inclined orientation with respect to the optical axis of the illumination optical system 10 .

[0168] According to this aspect, it is possible to provide a suitable configuration example for a fundus imaging device that is capable of wide-angle imaging and is compact.

[0169] In a non-limiting aspect, the fundus imaging apparatus 1 according to the embodiment includes a movement mechanism 14D for adjusting the focus of the illumination optical system 10. The movement mechanism 14D moves the slit member 14 in a direction along the optical axis of the illumination optical system 10 (optical axis direction). The movement mechanism 14D can function as an example of a second focusing mechanism.

[0170] According to this aspect, the focus of the illumination optical system 10 can be adjusted according to the diopter of the subject's eye, etc. This allows the fundus imaging device 1 capable of wide-angle imaging to be miniaturized, and also allows for improved image quality.

[0171] In conventional fundus imaging devices such as the invention described in Patent Document 2 (JP 2022-184520 A), imaging is performed while the subject presses their face against a pad provided on the device and looks into the device with their eye, which places a heavy burden on the subject. With the fundus imaging device 1 according to the embodiment, this problem can be at least partially resolved by devising the design of the optical system (particularly the first elliptical concave mirror 51 and the second elliptical concave mirror 52) and / or by applying the technology of the modified example described below.

[0172] Several non-limiting modifications of the fundus imaging apparatus 1 according to the embodiment will be described.

[0173] Generally, fundus photography is performed on each of the left and right eyes of a subject. A non-limiting aspect of the fundus photography device 1 according to the embodiment may be configured to switch between photographing the fundus of the left eye and the fundus of the right eye by moving the illumination optical system 10, the photographing optical system 20, the hole mirror 30, and the relay optical system 50.

[0174] As shown in Fig. 7, the fundus imaging device 1 of such an embodiment includes a measurement head 100, which is a unit that houses an illumination optical system 10, an imaging optical system 20, a hole mirror 30, and a relay optical system 50, and a movement mechanism 100D that moves the measurement head 100. In Fig. 7, the same elements as those in Figs. 1, 2, and 6 are denoted by the same reference numerals. Unless otherwise specified, descriptions of the same elements as those in Figs. 1, 2, and 6 will be omitted.

[0175] The manner in which the measuring head 100 is moved by the moving mechanism 100D will be described with reference to FIGS.

[0176] As shown in FIG. 8 , the moving mechanism 100D is configured to rotate the measurement head 100 along a trajectory T centered on a rotation center C. For example, the moving mechanism 100D is provided with an actuator that generates a driving force and a transmission mechanism that transmits this driving force. The moving mechanism 100D moves the measurement head 100 by transmitting the driving force generated by the operation of the actuator under the control of the main control unit 61 to the measurement head 100 via the transmission mechanism. This allows the measurement head 100 (second elliptical concave mirror 52) to be positioned immediately in front of the left eye EL when photographing the subject's left eye EL, and the measurement head 100 (second elliptical concave mirror 52) to be positioned immediately in front of the right eye ER when photographing the right eye ER. The configuration of the moving mechanism 100D is not limited to an electrically operated mechanism. Some embodiments of the moving mechanism 100D may be manual mechanisms that include a transmission mechanism that transmits power applied by user operation but do not include an actuator.

[0177] As described above, in this embodiment, it is possible to photograph both the left and right eyes by moving a single measurement head 100, and there is no need to provide separate measurement heads for the left and right eyes. Therefore, it is possible to miniaturize the fundus imaging device 1 capable of wide-angle imaging. It should be noted that, according to the embodiment, it is possible to use a curved mirror (e.g., an elliptical concave mirror) with smaller dimensions than conventional devices. Therefore, even when both a measurement head for the left eye and a measurement head for the right eye are provided, it is possible to miniaturize the device compared to similar conventional fundus imaging devices (i.e., conventional fundus imaging devices having both a measurement head for the left eye and a measurement head for the right eye).

[0178] The arrangement of the optical systems within the measurement head 100 of this embodiment will be described below. As shown in Fig. 9, the illumination optical system 10, the photographing optical system 20, the hole mirror 30, the first elliptical concave mirror 51, and the second elliptical concave mirror 52 are attached to a substrate 101. The first elliptical concave mirror 51 and the second elliptical concave mirror 52 are arranged on the side of the substrate 101 facing the test eyes (left eye EL, right eye ER), and the illumination optical system 10, the photographing optical system 20, and the hole mirror 30 are arranged on the side of the substrate 101 opposite the test eyes.

[0179] By arranging the optical system in this manner, it is possible to reduce the size of the measurement head 100, and also to reduce the size and power required for the moving mechanism 100D (reduction in the driving force required to move the measurement head 100).

[0180] Furthermore, by devising the arrangement of the optical system, it is possible to reduce the possibility of the measurement head 100 hitting the subject's head H. Examples of devising the arrangement of the optical system include devising the relative positional relationship between the first elliptical concave mirror 51 and the second elliptical concave mirror 52 (see, for example, FIGS. 3 to 5 ), and devising the arrangement of the illumination optical system 10, the imaging optical system 20, and the hole mirror 30. In the example of FIG. 9 , by arranging the illumination optical system 10, the imaging optical system 20, and the hole mirror 30 on the surface of the substrate 101 opposite the head H, it is possible to prevent these optical elements from hitting the subject's head H.

[0181] Another modification of the fundus imaging device 1 according to the embodiment will be described. In the above embodiment, asymmetric aberrations are reduced by configuring the imaging optical system 20 (light-receiving optical system) as a decentered optical system, thereby enabling a compact curved mirror (e.g., an elliptical concave mirror). However, methods for reducing asymmetric aberrations are not limited to the use of a decentered optical system. For example, optical methods using prisms or free-form surfaces (aspherical surfaces) and / or image processing methods that apply aberration correction processing to constructed images can also be employed to reduce asymmetric aberrations. Image processing methods may use, for example, software equipped with a predetermined aberration correction algorithm or a machine learning model trained on aberration correction. The aberration reduction effect may be improved by at least partially combining two or more methods for reducing asymmetric aberrations.

[0182] Another modification of the fundus imaging device 1 according to the embodiment will now be described. In the above embodiment, a configuration for collecting detection results of returned light using a rolling shutter readout method has been described, but the embodiment is not limited to this. For example, some aspects of the fundus imaging device 1 include a movable slit configured with hardware such as a focal plane shutter. This movable slit is disposed near the light-receiving surface of the image sensor 21 or disposed in a position that is optically approximately conjugate with the light-receiving surface of the image sensor 21. This modification simplifies the control for reading out detection results of returned light obtained by the image sensor 21.

[0183] Another modification of the fundus imaging device 1 according to the embodiment will now be described. This example provides an example of switching between photographing the fundus of the right eye and the fundus of the left eye. This example can be used instead of the movement of the measurement head 100 shown in FIGS. 8 and 9. The configuration of the fundus imaging device 1 of this example may be the same as that shown in FIG. 7. Hereinafter, reference will be made to FIG. 7. Also, reference will be made to FIGS. 10 and 11.

[0184] The moving mechanism 100D moves the first curved mirror and the second curved mirror. As described above, the moving mechanism 100D is electrically or manually operated. The first curved mirror and the second curved mirror may be any of the various types described above. In this example, the first curved mirror and the second curved mirror are a first elliptical concave mirror 51 and a second elliptical concave mirror 52, respectively. However, the embodiment is not limited to this.

[0185] The moving mechanism 100D of this example may be configured to move the measurement head 100 that houses the illumination optical system 10, the imaging optical system 20, the hall mirror 30, and the relay optical system 50. The elements moved by the moving mechanism 100D are not limited to those of this example and may include at least a first curved mirror and a second curved mirror. For example, the measurement head 100 may include a subunit that includes at least a first elliptical concave mirror 51 and a second elliptical concave mirror 52, and the moving mechanism 100D may be configured to move this subunit.

[0186] The moving mechanism 100D is configured to integrally rotate the first elliptical concave mirror 51 and the second elliptical concave mirror 52 around an axis (rotation axis) perpendicular to the arrangement direction of the subject's left and right eyes (i.e., the X direction). In other words, the moving mechanism 100D is configured to integrally rotate the first elliptical concave mirror 51 and the second elliptical concave mirror 52 around a rotation axis parallel to the subject's anterior-posterior axis (dorsal-ventral axis). The moving mechanism 100D configured in this manner rotates the first elliptical concave mirror 51 and the second elliptical concave mirror 52 integrally within the XY plane. The rotation axis may be a shaft member included in the moving mechanism 100D or may be a virtual axis. The orientation of the rotation axis may or may not be strictly parallel to the subject's anterior-posterior axis. For example, there may be an angular error between the orientation of the rotation axis and the subject's anterior-posterior axis that is acceptable from the standpoint of device design and use. Alternatively, an intentional angular difference may be provided between the direction of the rotation axis and the subject's anterior-posterior axis based on the design and use of the device. The rotation axis is positioned so that the positional correspondence of the first elliptical concave mirror 51 and the second elliptical concave mirror 52 with respect to the subject's left and right eyes can be switched. For example, the rotation axis is positioned so as to pass through a position between the left and right eyes. In some embodiments, the rotation axis may be positioned so as to pass through a midpoint (midline) between the subject's left and right eyes. The rotation angle range of the first elliptical concave mirror 51 and the second elliptical concave mirror 52 by the movement mechanism 100D is 180 degrees or more.

[0187] The moving mechanism 100D may further be configured to move the first elliptical concave mirror 51 and the second elliptical concave mirror 52 in a direction along the anterior-posterior axis of the subject.

[0188] When the fundus imaging device 1 is not being used to image an eye, the first elliptical concave mirror 51 and the second elliptical concave mirror 52 may be placed at a predetermined reference position. The reference position may be an arrangement in which the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are aligned in the left-right direction (X direction) as shown in Fig. 10, an arrangement in which the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are aligned in the up-down direction (Y direction), or another arrangement. The reference position may also be a position farther away from the subject's eye than the position (imaging position) when the subject's eye is imaged.

[0189] An example of switching between fundus photography of the right eye and fundus photography of the left eye will be described. As shown in the left diagram of FIG. 10 , when the subject's eye is the right eye ER, the second elliptical concave mirror 52 is arranged in front of the right eye ER, and the first elliptical concave mirror 51 is arranged in front of the left eye EL. Also, as shown in the right diagram of FIG. 10 , when the subject's eye is the left eye EL, the second elliptical concave mirror 52 is arranged in front of the left eye EL, and the first elliptical concave mirror 51 is arranged in front of the right eye ER. In this example, the positional correspondence relationship between the first elliptical concave mirror 51 and the second elliptical concave mirror 52 with respect to the right eye ER and the left eye EL is switched depending on whether the subject's eye is the right eye ER or the left eye EL. The moving mechanism 100D of this example switches between fundus photography of the right eye and fundus photography of the left eye by rotating the measurement head 100 180 degrees around the rotation center C1 shown in FIG. 10 by electric or manual operation. In other words, the moving mechanism 100D of this example switches between photographing the fundus of the right eye and the fundus of the left eye by rotating the measurement head 100 by 180 degrees around an axis that is parallel to the anterior-posterior axis of the subject and passes through the rotation center C1, either electrically or manually. The direction in which the measurement head 100 is rotated may be clockwise or counterclockwise in FIG. 10 .

[0190] An example of the procedure for switching between fundus photography of the right eye and fundus photography of the left eye will be described. The upper left diagram of Fig. 11 is a top view corresponding to the left diagram (front view) of Fig. 10. The upper right diagram of Fig. 11 is a top view corresponding to the right diagram (front view) of Fig. 10. This example describes switching from a state in which fundus photography of the right eye ER is performed as shown in the upper left diagram of Fig. 11 to a state in which fundus photography of the left eye EL is performed as shown in the upper right diagram of Fig. 11. Conversely, those skilled in the art will understand that switching from a state in which fundus photography of the left eye EL is performed as shown in the upper right diagram of Fig. 11 to a state in which fundus photography of the right eye ER is performed as shown in the upper left diagram of Fig. 11 can also be performed in a similar procedure.

[0191] Although not shown in the drawings, the moving mechanism 100D is electrically or manually operated to move the first elliptical concave mirror 51 and the second elliptical concave mirror 52 from the state in which they are disposed at the reference positions described above to the state shown in the upper left diagram of Fig. 11. In the state in which the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are disposed as shown in the upper left diagram of Fig. 11, the fundus imaging device 1 applies fundus imaging to the right eye ER.

[0192] After the fundus photographing of the right eye ER is performed, the moving mechanism 100D is electrically or manually operated to move the first elliptical concave mirror 51 and the second elliptical concave mirror 52 from the position shown in the upper left diagram of Fig. 11 to the position shown in the lower left diagram of Fig. 11. The lower left diagram of Fig. 11 shows a first moving operation M1 in which the second elliptical concave mirror 52 arranged in front of the right eye ER and the first elliptical concave mirror 51 arranged in front of the left eye EL are moved together in a direction away from the head H of the subject.

[0193] After performing the first movement operation M1, the movement mechanism 100D, by electrical or manual operation, moves the first elliptical concave mirror 51 and the second elliptical concave mirror 52 from the position shown in the lower left diagram of Fig. 11 to the position shown in the lower right diagram of Fig. 11. The lower right diagram of Fig. 11 shows a second movement operation M2 in which the second elliptical concave mirror 52 positioned in front of the right eye ER and the first elliptical concave mirror 51 positioned in front of the left eye EL are rotated together by 180 degrees to position the second elliptical concave mirror 52 in front of the left eye EL and the first elliptical concave mirror 51 in front of the right eye ER. The second movement operation M2 is an operation that alternates the positional correspondence relationship of the first elliptical concave mirror 51 and the second elliptical concave mirror 52 with respect to the right eye ER and the left eye EL.

[0194] After performing the second movement operation M2, the movement mechanism 100D, by electrical or manual operation, moves the first elliptical concave mirror 51 and the second elliptical concave mirror 52 from the position shown in the lower right diagram of Fig. 11 to the position shown in the upper right diagram of Fig. 11. The upper right diagram of Fig. 11 shows a third movement operation M3 in which the first elliptical concave mirror 51 and the second elliptical concave mirror 52 are moved together in a direction approaching the subject's head H, thereby positioning the second elliptical concave mirror 52 in front of the left eye EL and the first elliptical concave mirror 51 in front of the right eye ER. In the position of the first elliptical concave mirror 51 and the second elliptical concave mirror 52 shown in the upper right diagram of Fig. 11, the fundus imaging device 1 performs fundus imaging on the left eye EL.

[0195] According to this example, the moving distance of the first elliptical concave mirror 51 and the second elliptical concave mirror 52 can be shortened compared to the switching modes of the imaging target eye shown in Figures 8 and 9, thereby enabling faster movement and shorter movement time. Also, according to this example, the imaging target eye can be switched while maintaining the orientation of the subject's head, thereby reducing the burden on the subject. Furthermore, according to the mode shown in Figure 11, the measuring head 100 is rotated while being retracted from the subject's head H, thereby preventing the measuring head 100 from contacting or colliding with the subject.

[0196] The embodiments and non-limiting aspects described in this disclosure are merely examples for implementing the present invention, and those who intend to implement the present invention may make any modifications, omissions, additions, etc. within the scope of the gist of the present invention.

[0197] REFERENCE SIGNS LIST 1 Fundus imaging device 10 Illumination optical system 11 Illumination light source 14 Slit member 14D Moving mechanism 16 Optical scanner 20 Imaging optical system 20D Moving mechanism 21 Image sensor 22, 22a, 22b, 23 Lens group 50 Relay optical system 51 First elliptical concave mirror 52 Second elliptical concave mirror 100 Measuring head 100D Moving mechanism

Claims

1. A fundus photography device for photographing the fundus of a subject's eye, comprising: an illumination optical system including a light source that generates illumination light and an optical scanner that deflects the illumination light; a first curved mirror that reflects the illumination light from the illumination optical system; a second curved mirror that has a curvature distribution different from that of the first curved mirror and reflects the illumination light reflected by the first curved mirror and guides it to the subject's eye; and a light-receiving optical system that detects return light of the illumination light projected onto the fundus of the subject's eye via the second curved mirror and the first curved mirror, wherein each of the first curved mirror and the second curved mirror has one or more focal points, and the first curved mirror and the second curved mirror share a single focal point, and the light-receiving optical system includes: a first lens group; a second lens group that is disposed eccentrically with respect to the first lens group; and an image sensor that detects the return light that has passed through the first lens group and the second lens group. Fundus photography device.

2. The fundus imaging device according to claim 1, wherein the image sensor is disposed at an angle with respect to both the optical axis of the first lens group and the optical axis of the second lens group.

3. The fundus photography device according to claim 1, wherein the light receiving optical system further includes a third lens group that is disposed eccentrically with respect to both the first lens group and the second lens group, and the image sensor detects the returning light that has passed through the first lens group, the second lens group, and the third lens group.

4. The fundus photographing device according to claim 3, wherein the image sensor is disposed at an angle with respect to the optical axis of the first lens group, the optical axis of the second lens group, and the optical axis of the third lens group.

5. The fundus photography device of claim 3 or 4, wherein the returning light passes through the first lens group, the second lens group, and the third lens group in this order and is guided to the image sensor, and further comprises a first focusing mechanism that moves the second lens group, the third lens group, and the image sensor integrally.

6. A fundus imaging device according to any one of claims 1 to 5, wherein the first curved mirror and the second curved mirror are a first elliptical concave mirror and a second elliptical concave mirror, respectively.

7. The fundus imaging device of claim 6, wherein the major axis of the first elliptical concave mirror and the major axis of the second elliptical concave mirror are each within the range of 70 to 80 mm, and the minor axis of the first elliptical concave mirror and the minor axis of the second elliptical concave mirror are each within the range of 50 to 60 mm.

8. A fundus imaging device according to claim 6 or 7, wherein the first elliptical concave mirror and the second elliptical concave mirror are arranged so that a plane including the major axis of the first elliptical concave mirror and a plane including the major axis of the second elliptical concave mirror are non-parallel to each other.

9. The fundus imaging device according to claim 8, wherein the first elliptical concave mirror and the second elliptical concave mirror are arranged so that the plane including the major axis of the first elliptical concave mirror and the plane including the major axis of the second elliptical concave mirror are perpendicular to each other.

10. A fundus imaging device according to any one of claims 1 to 9, wherein the illumination optical system further includes a slit member having a slit opening, the illumination light generated by the light source is projected onto the slit member, and the optical scanner deflects the illumination light that has passed through the slit opening.

11. The fundus photographing device according to claim 10, wherein the slit member is disposed at an angle with respect to the optical axis of the illumination optical system.

12. The fundus imaging device according to claim 10 or 11, further comprising a second focusing mechanism that moves the slit member in the optical axis direction of the illumination optical system.

13. A fundus photography device according to any one of claims 1 to 12, further comprising a movement mechanism for moving the first curved mirror and the second curved mirror, wherein when the subject's eye is a right eye, the second curved mirror is positioned in front of the right eye and the first curved mirror is positioned in front of the left eye, and when the subject's eye is a left eye, the second curved mirror is positioned in front of the left eye and the first curved mirror is positioned in front of the right eye.

14. The fundus imaging device according to claim 13, wherein the movement mechanism rotates the first curved mirror and the second curved mirror integrally around an axis parallel to the anterior-posterior axis of the subject.

15. The fundus imaging device of claim 14, wherein the moving mechanism further moves the first curved mirror and the second curved mirror in a direction along the anterior-posterior axis, and when switching the subject's eye from the first eye to the second eye, the moving mechanism moves the second curved mirror placed in front of the first eye and the first curved mirror placed in front of the second eye together in a direction away from the subject, rotates the first curved mirror and the second curved mirror together around the axis, and moves the first curved mirror and the second curved mirror in a direction approaching the subject to position the first curved mirror in front of the first eye and the second curved mirror in front of the second eye.

Images