JP7476857B2 - Fundus photography device - Google Patents

Description

The present invention relates to a fundus imaging device.

There is known an ophthalmologic device that incorporates an optical system that guides incident light for fundus photography to the subject's retina and guides reflected light from the subject's retina to a photodetector, and an optical system that guides a scanning light beam for treatment or targeting to the subject's retina (for example, Patent Document 1). There is also known a scanning laser ophthalmoscope (SLO) that scans a light beam, irradiates the subject's retina, and obtains a fundus image by detecting the reflected light from the retina with a photodetector.

JP 2011-512916 A

Projectors are known that project images by scanning light rays two-dimensionally and emitting them to the outside. When configuring an ophthalmic device using such a projector, it is necessary to obtain a fundus image using the light rays that are scanned two-dimensionally and emitted from the projector.

The present invention has been developed in consideration of the above problems, and aims to make it possible to acquire fundus images.

The present invention relates to a light source that emits a light beam, a scanning unit that scans the light beam two-dimensionally,
The fundus photography device comprises: a first optical component that converges the multiple light beams scanned by the scanning unit and emitted at different times to a first convergence point near the subject's pupil and then irradiates the multiple light beams onto the subject's retina; a second optical component that converges the multiple reflected light beams that are reflected by the subject's retina and pass through the first optical component to a second convergence point; an optical system that is positioned at the second convergence point and converts each of the multiple reflected light beams into convergent light; a photodetector that detects the multiple reflected light beams that pass through the optical system; and an image generation unit that generates a fundus image based on an output signal from the photodetector , wherein the scanning unit and the first convergence point are in an approximately conjugate positional relationship .

The present invention is a fundus photography device comprising: a light source that emits a light beam; a scanning unit that scans the light beam two-dimensionally; a first optical component that converges the multiple light beams scanned by the scanning unit and emitted at different times to a first convergence point near the subject's pupil and then irradiates the multiple light beams onto the subject's retina; a second optical component that converges multiple reflected light beams that are reflected by the subject's retina and transmitted through the first optical component to a second convergence point; an optical system that is disposed at the second convergence point and converts each of the multiple reflected light beams into convergent light; a photodetector that detects the multiple reflected light beams that have transmitted through the optical system; and an image generation unit that generates a fundus image based on an output signal from the photodetector, wherein the beam diameter of the light beam incident on the subject's cornea is 0.8 mm or more and 1.65 mm or less .

The present invention is a fundus photography device comprising a projector, a projection unit, and an image generation unit, wherein the projector comprises a light source that emits a light beam, a scanning unit that scans the light beam two-dimensionally, and an emission unit that emits the scanned light beam, and the projection unit comprises a first optical component that converges the multiple light beams emitted from the projector at different times to a first convergence point near the subject's pupil and then irradiates the multiple light beams onto the subject's retina, a second optical component that converges multiple reflected light beams that are reflected by the subject's retina and transmitted through the first optical component to a second convergence point, an optical system that is disposed at the second convergence point and converts each of the multiple reflected light beams into convergent light, and a photodetector that detects the multiple reflected light beams that have transmitted through the optical system, and the image generation unit generates a fundus image based on an output signal from the photodetector, and the scanning unit and the first convergence point are in an approximately conjugate positional relationship.

The present invention is a fundus photography device comprising a projector, a projection unit, and an image generation unit, wherein the projector comprises a light source that emits a light beam, a scanning unit that scans the light beam two-dimensionally, and an emission unit that emits the scanned light beam, and the projection unit comprises a first optical component that converges the multiple light beams emitted from the projector at different times to a first convergence point near the subject's pupil and then irradiates the multiple light beams onto the subject's retina, a second optical component that converges multiple reflected light beams that are reflected by the subject's retina and transmitted through the first optical component to a second convergence point, an optical system that is disposed at the second convergence point and converts each of the multiple reflected light beams into convergent light, and a photodetector that detects the multiple reflected light beams that have transmitted through the optical system, and the image generation unit generates a fundus image based on an output signal from the photodetector, and a beam diameter of the light beam incident on the subject's cornea is 0.8 mm or more and 1.65 mm or less.

The present invention is a fundus photography device comprising a projector, a projection unit, and an image generation unit, wherein the projector comprises a light source that emits a light beam, a scanning unit that scans the light beam two-dimensionally, and an emission unit that emits the scanned light beam, and the projection unit comprises a first optical component that converges the multiple light beams emitted from the projector at different times to a first convergence point near the subject's pupil and then irradiates the multiple light beams onto the subject's retina, a second optical component that converges multiple reflected light beams that are reflected by the subject's retina and pass through the first optical component to a second convergence point, an optical system that is positioned at the second convergence point and converts each of the multiple reflected light beams into convergent light, and a photodetector that detects the multiple reflected light beams that pass through the optical system, wherein the image generation unit generates a fundus image based on an output signal from the photodetector, and the projection unit has a detachable unit that is detachable from the projector.

In the above configuration, the first convergence point and the second convergence point are located at substantially conjugate positions,
The subject's retina and the photodetector may be configured to be in a substantially conjugate position .

In the above configuration , the first optical component converges the multiple light rays to the first convergence point and converts each of the multiple light rays from diffuse light to approximately parallel light, the second optical component converges the multiple reflected light rays to the second convergence point and converts each of the multiple reflected light rays from diffuse light to approximately parallel light, and the optical system can be configured to convert each of the multiple reflected light rays from approximately parallel light to convergent light .

In the above configuration, the plurality of reflected light beams may be focused in front of the second optical component, and become diffused light to be incident on the second optical component .

The above-described configuration may further include a third optical component disposed between the second optical component and the optical system, and configured to refract the plurality of reflected light beams .

According to the present invention, fundus images can be obtained.

FIG. 1 is a block diagram of a fundus imaging apparatus according to a first embodiment. FIG. 2 is a diagram showing an optical system of the fundus photographing apparatus according to the first embodiment. FIG. 3 is a diagram showing a pseudo-eye optical system. FIG. 4 is a diagram showing the scanning of a light beam on a subject's retina. FIG. 5 is a flowchart showing an example of fundus photographing processing. FIG. 6 is a diagram showing an optical system of a fundus photographing apparatus according to the second embodiment. FIG. 7 is a diagram showing an optical system of a fundus photographing apparatus according to the third embodiment. FIG. 8 is a diagram showing an optical system of a fundus photographing apparatus according to the fourth embodiment. 9(a) is an external perspective view of a fundus imaging apparatus according to Example 5, FIG. 9(b) is an external view seen from the arrow A in FIG. 9(a), and FIG. 9(c) is an external view seen from the arrow B in FIG. 9(a). FIG. 10 is a diagram showing an optical system of a fundus photographing apparatus according to the fifth embodiment. FIG. 11 is a diagram showing the trajectories of light rays reflected by the cornea of a subject. FIG. 12A is a diagram showing the trajectory of a light ray reflected from the retina, and FIG. 12B is an enlarged view of the vicinity of the pseudo-eye optical system of FIG. 12A. FIG. 13A is a diagram showing the trajectories of light rays reflected by the cornea, and FIG. 13B is an enlarged view of the vicinity of the pseudo-eye optical system of FIG. 13A. FIG. 14(a) is a diagram showing only the optical axis of the light beam in FIG. 13(a), and FIG. 14(b) and FIG. 14(c) are diagrams showing the trajectories of two of the three light beams in FIG. 13(a). FIG. 15 is a block diagram of a fundus imaging apparatus according to the sixth embodiment. 16A to 16D are diagrams showing the optical system of a fundus photographing apparatus according to the sixth embodiment. FIG. 17 is a diagram showing an example of a retinal reflected light ray having a half-split shape. FIG. 18 is a flowchart showing an example of fundus photographing processing. 19A and 19B are diagrams showing an optical system of a fundus imaging apparatus according to a first modified example of the sixth embodiment. 20(a) to 20(c) are diagrams showing changes in the focal point position of the corneal reflected light beam due to differences in the radius of curvature of the cornea. FIG. 21 is a diagram showing an example in which the light blocking plate arranged on the imaginary plane has a U-shape. 22(a) and 22(b) are diagrams showing problems that arise when a flat light-shielding plate is used to block corneal reflected light. FIG. 23 is a diagram showing an optical system of a fundus photographing apparatus according to the seventh embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

Fig. 1 is a block diagram of a fundus imaging device according to a first embodiment. Referring to Fig. 1, the fundus imaging device 100 includes a projection unit 10, a control unit 30, and a photodetector 40. The fundus imaging device 100 may include a display unit 41 that is removable or integrated. The projection unit 10 includes a light source 11, a scanning unit 12, an optical system 13, a driving circuit 14, and an input circuit 15. The control unit 30 includes an image control unit 31, a signal processing unit 32, and an image generating unit 33. The light source 11, the scanning unit 12, the driving circuit 14, the input circuit 15, and the image control unit 31 are included in a projector 16 that scans light rays two-dimensionally and emits the light rays to the outside. The projector 16 is, for example, a general laser scanning projector.

The image control unit 31 generates an image to be projected onto the subject's retina. An image signal is input from the image control unit 31 to the input circuit 15. The drive circuit 14 drives the light source 11 and the scanning unit 12 based on the control signal from the image control unit 31 and the image signal acquired by the input circuit 15.

The light source 11 may emit invisible light, which is infrared laser light, or may emit visible light of a single wavelength, which is red laser light, green laser light, or blue laser light, or may emit white light including these. The wavelength of the infrared laser light may be about 785 nm to 1.4 μm, the wavelength of the red laser light may be about 610 nm to 660 nm, the wavelength of the green laser light may be about 515 nm to 540 nm, and the wavelength of the blue laser light may be about 440 nm to 480 nm.

The scanning unit 12 is, for example, a scanning mirror such as a MEMS (Micro Electro Mechanical System) mirror or a transmissive scanner, and scans the light beam 50 emitted by the light source 11 in two dimensions.

The optical system 13 irradiates the two-dimensionally scanned light beam 50 onto the subject's eye 70. The reflected light beam 51 reflected by the retina of the subject's eye 70 enters the photodetector 40 via the optical system 13. The photodetector 40 detects the reflected light beam 51. The photodetector 40 includes an imaging element such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor.

The signal processing unit 32 processes the output signal of the photodetector 40 based on a control signal from the image control unit 31. The image generation unit 33 generates a fundus image based on the signal obtained by processing the output signal of the photodetector 40 by the signal processing unit 32. The display unit 41 is, for example, a liquid crystal display, and displays the image generated by the image generation unit 33.

The image control unit 31, the signal processing unit 32, and the image generation unit 33 may be processed by a processor such as a CPU (Central Processing Unit) working in cooperation with a program. The image control unit 31, the signal processing unit 32, and the image generation unit 33 may be circuits designed specifically for them. The image control unit 31, the signal processing unit 32, and the image generation unit 33 may be a single circuit or different circuits.

2 is a diagram showing the optical system of the fundus imaging device according to the first embodiment. In FIG. 2, the light beam 50 and the reflected light beam 51 are shown with their respective finite light beam diameters, and their centers are shown by dotted lines. Referring to FIG. 2, the projector 16 includes a light source 11, a scanning unit 12, a collimating lens 17, a mirror 18, optical components 19, and an attenuation filter 20. The light source 11, the scanning unit 12, the collimating lens 17, and the mirror 18 are arranged in a housing 29. The optical components 19 and the attenuation filter 20 are attached to the outside of the housing 29. The optical components 19 and the attenuation filter 20 may be arranged in the housing 29, or may be arranged apart from the housing 29 without being provided in the projector 16. The light beam 50 emitted by the light source 11 is converted from diffused light to approximately parallel light by the collimating lens 17, and then reflected by the mirror 18 and enters the scanning unit 12. The approximately parallel light is not limited to completely parallel light, but also includes a case where the light is slightly converged or diffused.

The light beam 50 scanned two-dimensionally by the scanning unit 12 passes through the optical component 19 and the attenuation filter 20. The optical component 19 is, for example, a condenser lens, which converts the multiple light beams 50 emitted from the scanning unit 12 at different times and whose optical axes are divergent into multiple light beams 50 whose optical axes are approximately parallel to each other, and converts each light beam 50 from approximately parallel light into convergent light. The multiple light beams 50 emitted from the scanning unit 12 at different times can also be collectively referred to as scanning light. The attenuation filter 20 is, for example, an ND filter, and adjusts the amount of light of the light beam 50. The projector 16 may be provided with multiple attenuation filters 20 with different amounts of adjustment of the amount of light, and the attenuation filter 20 through which the light beam 50 passes may be switchable. This allows the amount of light of the light beam 50 emitted from the projector 16 to be appropriately changed depending on the intended use, etc.

The multiple light beams 50 emitted from the projector 16 are reflected by the optical component 21 and enter the optical component 22. The optical component 21 is a half mirror. Each of the multiple light beams 50 is focused in front of the optical component 22, and then becomes diffused light and enters the optical component 22. The optical component 22 is, for example, a condenser lens, and converts the multiple light beams 50 whose optical axes are approximately parallel to each other into multiple light beams 50 whose optical axes converge to each other, and converts each light beam 50 from diffused light to approximately parallel light. The approximately parallel light here means that the light beams 50 are approximately parallel to the extent that they can be focused on the subject's retina 74, and the term "parallel" is also used to include approximately parallel light. The multiple light beams 50 that have passed through the optical component 22 converge at a convergence point 52 near the pupil 71 of the subject's eye 70, pass through the crystalline lens 72 and the vitreous body 73, and are irradiated onto the retina 74. The beam diameter (diameter) of each light ray 50 when it enters the cornea 75 is approximately 0.8 mm to 1.65 mm. Each light ray 50 is converted from approximately parallel light to convergent light by the crystalline lens 72, and is focused approximately on the retina 74. In this way, the light ray 50 is irradiated onto the subject's retina 74 using Maxwellian vision.

The light ray 50 is reflected by the subject's retina 74. The reflected light ray 51 reflected by the retina 74 passes through the optical component 22 and the optical component 21 and enters the optical component 23. The optical component 22 converts the multiple reflected light rays 51 reflected by the retina 74, whose optical axes are divergent, into multiple reflected light rays 51 whose optical axes are approximately parallel to each other, and converts each reflected light ray 51 from approximately parallel light to convergent light. The reflected light ray 51 is focused in front of the optical component 23, and then becomes diffuse light and enters the optical component 23. The optical component 23 is, for example, a focusing lens, and converts the multiple reflected light rays 51 whose optical axes are approximately parallel to each other into multiple reflected light rays 51 whose optical axes are convergent to each other, and converts each reflected light ray 51 from diffuse light to approximately parallel light.

The pseudo-eye optical system 24 is disposed at a convergence point 53 where multiple reflected light rays 51 that have passed through the optical component 23 converge. The pseudo-eye optical system 24 is composed of multiple lenses, and converts the reflected light rays 51 from approximately parallel light to convergent light. After being converted to convergent light by the pseudo-eye optical system 24, the reflected light rays 51 are focused on the planar detection surface (imaging surface) 40a of the photodetector 40 or in the vicinity of the detection surface 40a. The scanning unit 12, the convergence point 52, and the convergence point 53 are in approximately conjugate positions. The approximately conjugate position includes cases where the position is shifted from the conjugate position by the amount of manufacturing error, and the term "conjugate" is also used to include approximately conjugate.

Figure 3 is a diagram showing a pseudo-eye optical system. In Figure 3, the center of the finite light beam diameter of the reflected light ray 51 is indicated by a dotted line. Referring to Figure 3, the pseudo-eye optical system 24 is composed of, for example, a convex lens 24a, a concave lens 24b, and a convex lens 24c. The reflected light ray 51 is converted from approximately parallel light to convergent light by the convex lens 24a, converted from convergent light to divergent light by the concave lens 24b, and converted from divergent light to convergent light by the convex lens 24c again, and focused on the detection surface 40a of the photodetector 40 or in the vicinity of the detection surface 40a. The convex lens 24a is a plano-convex lens in which the surface on the side on which the reflected light ray 51 is incident is a convex surface and the surface on the side on which it is emitted is a flat surface. The concave lens 24b is a biconcave lens in which both the surface on which the reflected light ray 51 is incident and the surface on which it is emitted are concave surfaces. The convex lens 24c is a plano-convex lens in which the surface on which the reflected light ray 51 is incident is a flat surface and the surface on which it is emitted is a convex surface. Convex lenses 24a and 24c may be biconvex lenses in which both the side where reflected light ray 51 enters and the side where it exits are convex. Concave lens 24b may be a plano-concave lens in which one of the sides where reflected light ray 51 enters and the side where it exits is concave and the other side is flat.

The convex lens 24a and the concave lens 24b are arranged in contact with each other. The concave lens 24b and the convex lens 24c are arranged at a distance from each other. Note that the convex lens 24a and the concave lens 24b may be arranged at a distance smaller than the distance between the concave lens 24b and the convex lens 24c. The multiple reflected light rays 51 converge, for example, at the center of the convex surface of the convex lens 24a on which the reflected light rays 51 are incident, forming a convergence point 53.

The length dimension L from the convex surface of the convex lens 24a or the convergence point 53 to the detection surface 40a of the photodetector 40 corresponds to the distance from the surface of the crystalline lens or the surface of the cornea of the human eye to the surface of the retina, corrected taking into account the refractive index of the eye, and is, for example, 16 mm to 17 mm.

The optical components 21, 22, 23, and pseudo-eye optical system 24 in FIG. 2 correspond to the optical system 13 in FIG. 1. The optical components 22 and 23 may be the same as the optical components 19 provided in the projector 16. By making the optical components 22 and 23 the same, the manufacturing cost can be reduced. In addition, the optical components 21, 22, 23, pseudo-eye optical system 24, and the photodetector 40 are integrated into an optical system block, and a detachable part that can be attached to and detached from the projector 16 is provided, so that the optical system block and the projector 16 can be detached and replaced. As a result, if the projector 16 is a general-purpose projector that projects onto a wall or a screen, the general-purpose projector can be used as a fundus imaging device by connecting it to the optical system block.

Figure 4 is a diagram showing the scanning of a light beam on the subject's retina. Referring to Figure 4, the scanning unit 12 raster scans the light beam 50 on the retina 74 from the upper left to the lower right as indicated by the arrow 55. If the light source 11 does not emit the light beam 50 even when the scanning unit 12 is driven, the light beam 50 is not irradiated onto the retina 74. For example, the light beam 50 is not emitted at the dotted arrow 55 in Figure 4. The driving circuit 14 synchronizes the emission of the light beam 50 from the light source 11 with the driving of the scanning unit 12. This causes the light source 11 to emit the light beam 50 within a predetermined range (actual arrow 55) on the retina 74.

Figure 5 is a flowchart showing an example of fundus photography processing. Referring to Figure 5, the image control unit 31 controls the driving of the light source 11 and the scanning unit 12 to emit light beams 50 for fundus photography from the projector 16 and irradiate the light beams 50 on the retina 74 (step S10). The light beams 50 for fundus photography may be infrared laser light, white light including red laser light, green laser light, and blue laser light, or monochromatic light including laser light of a single wavelength. In the fundus photography processing in Figure 5, the light beams 50 are raster scanned from the upper left to the lower right on the retina 74 and irradiated on the entire retina 74. As described in Figure 2, when the light beams 50 are irradiated on the subject's retina 74, the reflected light beams 51 reflected by the retina 74 enter the photodetector 40.

Next, the signal processing unit 32 acquires the output signal of the photodetector 40 (step S12). Next, the image generating unit 33 generates a fundus image based on the signal obtained by processing the output signal of the photodetector 40 by the signal processing unit 32 (step S14). The display unit 41 displays the fundus image generated by the image generating unit 33 (step S16). A doctor can examine the fundus condition of the subject by closely examining the fundus image displayed on the display unit 41.

According to the first embodiment, as shown in FIG. 2, a plurality of light beams 50 (photographing light beams) for fundus photography emitted from the projector 16 at different times are converged by the optical component 22 (first optical component) at a convergence point 52 (first convergence point) near the pupil 71 of the subject, and then irradiated onto the retina 74 of the subject. A plurality of reflected light beams 51 (first reflected light beams) reflected by the retina 74 are converged to a convergence point 53 (second convergence point) by the optical component 23 (second optical component) after passing through the optical component 22. A pseudo-eye optical system 24 that converts the reflected light beams 51 into convergent light is disposed at the convergence point 53. A plurality of reflected light beams 51 are detected by the photodetector 40 after passing through the pseudo-eye optical system 24. The image generating unit 33 generates a fundus image based on the output signal of the photodetector 40. As a result, a fundus image can be acquired in the fundus photography device 100 configured using the projector 16 that scans and emits the light beams 50 in two dimensions.

In order to irradiate the light ray 50 to the subject's retina 74 using Maxwell's vision and detect the reflected light ray 51 reflected by the retina 74 with the photodetector 40, it is preferable that the convergence points 52 and 53 are in approximately conjugate positions. Also, in order for the light ray 50 to be focused on the subject's retina 74 and for the reflected light ray 51 to be focused on the detection surface 40a of the photodetector 40, it is preferable that the subject's retina 74 and the photodetector 40 are in approximately conjugate positions. An approximately conjugate position also includes a case where the light ray 50 is shifted from the conjugate position by the amount of manufacturing error.

As shown in FIG. 2, the optical component 22 converges the multiple light rays 50 to a convergence point 52 and converts each light ray 50 from diffuse light to approximately parallel light. This allows the light rays 50 to be focused on the subject's retina 74. The optical component 23 converges the multiple reflected light rays 51 to a convergence point 53 and converts each reflected light ray 51 from diffuse light to approximately parallel light, and the pseudo-eye optical system 24 converts the approximately parallel reflected light rays 51 to convergent light. This allows the reflected light rays 51 to be focused on the detection surface 40a of the photodetector 40.

It is preferable that the light ray 50 emitted from the projector 16 is reflected by the optical component 21 (third optical component) arranged between the optical components 22 and 23 and enters the optical component 22, and the reflected light ray 51 reflected by the retina 74 passes through the optical components 22 and 21 and enters the optical component 23. This allows the fundus imaging device 100 to be made smaller.

The block diagram of the fundus imaging device according to the second embodiment is the same as FIG. 1 of the first embodiment, and therefore the description will be omitted. FIG. 6 is a diagram showing the optical system of the fundus imaging device according to the second embodiment. Referring to FIG. 6, in the fundus imaging device 200 of the second embodiment, a quarter-wave plate 25 is disposed between the optical component 21a and the optical component 22. The optical component 21a is a polarizing beam splitter. The other configurations are the same as those of the first embodiment, and therefore the description will be omitted.

According to the second embodiment, the optical component 21a is a polarizing beam splitter, and a quarter-wave plate 25 is disposed between the optical component 21a and the optical component 22. As a result, when the projector 16 emits an S-wave light ray 50, the light ray 50 is reflected by the optical component 21a, passes through the quarter-wave plate 25, becomes circularly polarized light, and is irradiated onto the retina 74. The reflected light ray 51 reflected by the retina 74 passes through the quarter-wave plate 25, becomes a P-wave, passes through the optical component 21a, and enters the optical component 23. With this configuration, the light utilization efficiency is improved, and the optical S/N ratio can be improved.

The block diagram of the fundus imaging device according to the third embodiment is the same as FIG. 1 of the first embodiment, and therefore the description will be omitted. FIG. 7 is a diagram showing the optical system of the fundus imaging device according to the third embodiment. Referring to FIG. 7, in the fundus imaging device 300 of the third embodiment, the optical component 19 and the optical component 23 are the same component, but the focal length of the optical component 22a is shorter than those of the optical components 19 and 23. The rest of the configuration is the same as in the first embodiment, and therefore the description will be omitted.

According to the third embodiment, the focal length of the optical component 22a is shorter than that of the optical component 23. This increases the field of view (FOV) and increases the range over which the light beam 50 is irradiated onto the retina 74.

In Example 3, the focal length of optical component 22a is shorter than that of optical component 23, but it may be longer. In this case, the beam diameter of light ray 50 when it is incident on the subject's cornea can be increased, so that the spot diameter of light ray 50 on retina 74 is reduced, improving the resolution on retina 74 and the signal-to-noise ratio of the fundus image. In this way, the focal length of optical component 22a may be made different from that of optical component 23 in terms of the FOV and the beam diameter when it is incident on the cornea.

The block diagram of the fundus imaging device according to the fourth embodiment is the same as FIG. 1 of the first embodiment except for the addition of the light source 26, so the description will be omitted. FIG. 8 is a diagram showing the optical system of the fundus imaging device according to the fourth embodiment. Referring to FIG. 8, the fundus imaging device 400 according to the fourth embodiment further includes a light source 26 that emits background light 54 and an optical component 27 arranged between the optical component 21 and the optical component 22, in addition to the configuration of FIG. 2 of the first embodiment. The light source 26 is, for example, an LED light source or a laser light source. The optical component 27 is, for example, a half mirror. The background light 54 emitted by the light source 26 is reflected by the optical component 27 and enters the optical component 22. The background light 54 is converted from diffuse light to convergent light by the optical component 22, and is focused near the pupil 71 of the subject, and then irradiated onto the retina 74. The background light 54 from the light source 26 is emitted, for example, when the examiner turns on the light source 26. The other configurations are the same as those of the first embodiment, so the description will be omitted.

According to the fourth embodiment, the light source 26 is provided to emit background light 54. With only the light beam 50, a good fundus image may not be obtained due to insufficient light and/or unevenness due to scanning and stray light. By providing the light source 26, the background light 54 is irradiated onto the retina 74, increasing the overall brightness of the retina 74, making it possible to obtain a good fundus image. In this case, an optical component 27 (fourth optical component) is disposed between the optical components 22 and 23, and the background light 54 emitted from the light source 26 is reflected by the optical component 27, passes through the optical component 22, and is irradiated onto the subject's retina 74. This makes it possible to prevent the fundus imaging device 400 from becoming too large.

Fig. 9(a) is an external perspective view of the fundus imaging device according to the fifth embodiment, Fig. 9(b) is an external view seen from the arrow A in Fig. 9(a), and Fig. 9(c) is an external view seen from the arrow B in Fig. 9(a). With reference to Figs. 9(a) to 9(c), the fundus imaging device 500 of the fifth embodiment is a handy type fundus imaging device, and includes a housing 90 having a projection unit 10, a control unit 30, and a photodetector 40 therein, and a lens barrel 91 with which the subject aligns the eye 70. The width W of the fundus imaging device 500 is about 70 mm to 80 mm. The depth D1 is about 90 mm to 100 mm, and D2 is about 60 mm to 70 mm. The height H is about 150 mm to 160 mm.

Fig. 10 is a diagram showing the optical system of a fundus imaging device according to Example 5. Referring to Fig. 10, in the fundus imaging device 500 of Example 5, an optical component 28 that refracts the reflected light ray 51 is disposed between the optical component 23 and the pseudo-eye optical system 24. The optical component 28 is, for example, a mirror. Therefore, the reflected light ray 51 that passes through the optical component 23 is reflected and refracted by the optical component 28 before entering the pseudo-eye optical system 24.

In addition, the angle at which the direction in which optical components 22 and 23 face each other and the direction in which light ray 50 is emitted from projector 16 intersect is not a right angle. When an imaginary plane including the emission surface of projector 16 from which light ray 50 is emitted is taken as the reference plane, optical component 22 is positioned farther away from the imaginary plane than optical component 23. Therefore, light ray 50 emitted from projector 16 is reflected by optical component 21 diagonally upward in a direction away from projector 16 and enters optical component 22. The other configurations are the same as in Example 1, so a description thereof will be omitted.

According to the fifth embodiment, an optical component 28 (fifth optical component) that bends the reflected light ray 51 is disposed between the optical component 23 and the pseudo-eye optical system 24. This allows the fundus imaging device 500 to be miniaturized. For example, in FIG. 10, the circuits of the signal processing unit 32 and the image generating unit 33 can be disposed below the photodetector 40, allowing the fundus imaging device 500 to be miniaturized.

The light beam emitted from the projector 16 is reflected by the optical component 21 in an upward diagonal direction away from the projector 16 and enters the optical component 22. This allows the telescope tube 91 to be oriented diagonally upward as shown in FIG. 9(c), making it easier for the subject to align the eye 70 with the telescope tube 91.

As shown in FIG. 2, the light ray 50 emitted from the projector 16 passes through the cornea 75 and is irradiated onto the retina 74. Therefore, a part of the light ray 50 is reflected by the cornea 75. FIG. 11 is a diagram showing the trajectory of the light ray reflected by the subject's cornea. Referring to FIG. 11, a part of the light ray 50 emitted from the projector 16 is reflected by the cornea 75 to become a reflected light ray 56. The reflected light ray 56 passes through the optical components 22, 21, 23, and the pseudo-eye optical system 24 and enters the detection surface 40a of the photodetector 40. In the following, the reflected light ray 56 of the light ray 50 reflected by the cornea 75 may be referred to as the corneal reflected light ray 56, and the reflected light ray 51 of the light ray 50 reflected by the retina 74 may be referred to as the retinal reflected light ray 51. Since the radius of curvature of the surface of the cornea 75 is about 7.8 mm, the multiple corneal reflected light rays 56 are approximately overlapped with the multiple retinal reflected light rays 51. In other words, the area where the multiple corneal reflected light rays 56 are incident on the detection surface 40a of the photodetector 40 roughly overlaps with the area where the multiple retinal reflected light rays 51 are incident on the detection surface 40a of the photodetector 40.

The quantity of light of the corneal reflected light ray 56 is several tens of times greater than the quantity of light of the retinal reflected light ray 51. For this reason, when the corneal reflected light ray 56 is incident on the photodetector 40 in addition to the retinal reflected light ray 51, flare occurs in the image generated based on the output signal of the photodetector 40, which may make it difficult to capture a fundus image of the retina 74.

Figure 12(a) shows the trajectory of the light reflected by the retina, and Figure 12(b) is an enlarged view of the vicinity of the pseudo-eye optical system in Figure 12(a). Figure 13(a) shows the trajectory of the light reflected by the cornea, and Figure 13(b) is an enlarged view of the vicinity of the pseudo-eye optical system in Figure 13(a). Figure 14(a) shows only the optical axis of the light in Figure 13(a), and Figures 14(b) and 14(c) show the trajectories of two of the three light rays in Figure 13(a). Figures 12(a) to 14(c) show the case where the fundus imaging device is viewed from above, and show the case where the light ray 50 is irradiated only to one of the regions 74a and 74b obtained by dividing the retina 74 into two regions 74a and 74b on the left and right sides with respect to the center of the retina 74. The direction in which the light ray 50 enters the center of the retina 74 is the Z direction, the horizontal direction is the X direction, and the vertical direction is the Y direction. In addition, the center of the retina 74 is the origin, the direction from the center (origin) of the retina 74 toward the area 74a is the +X direction, and the direction from the center (origin) of the retina 74 toward the area 74b is the -X direction. The area located on the +X side of the entire fundus imaging device is the +X area, and the area located on the -X side is the -X area.

12(a) and 12(b), when the light ray 50 is irradiated to the region 74a of the retina 74, the light ray 50 enters the eye 70 from the -X region. The retinal reflected light ray 51 reflected from the region 74a of the retina 74 returns to the optical component 21 along a trajectory that is substantially the same as the trajectory of the light ray 50 entering the eye 70, and then passes through the optical component 21 and the optical component 23 to enter the pseudo-eye optical system 24. That is, the retinal reflected light ray 51 is emitted from the eye 70 to the -X region, passes through the optical component 22 and the optical component 21, and is bent by the optical component 23 toward the +X region to enter the pseudo-eye optical system 24. Although not shown in the figure, when the light ray 50 is irradiated to the region 74b of the retina 74, the light ray 50 enters the eye 70 from the +X region. The retinal reflected light ray 51 reflected at the region 74b of the retina 74 returns to the optical component 21 along a path that is substantially the same as the path that the light ray 50 took when it entered the eye 70, and then passes through the optical components 21 and 23 to enter the pseudo-eye optical system 24. That is, the retinal reflected light ray 51 is emitted from the eye 70 to the +X region, passes through the optical components 22 and 21, and is bent by the optical component 23 toward the -X region to enter the pseudo-eye optical system 24.

Referring to FIG. 13(a), FIG. 13(b), and FIG. 14(a), the corneal reflected light ray 56, which is the light ray 50 irradiated to the region 74a of the retina 74 and reflected by the cornea 75, is reflected toward the +X region by the convex curved surface shape of the cornea 75. The corneal reflected light ray 56 passes through the optical components 22 and 21, then bends toward the -X region by the optical component 23, and enters the pseudo-eye optical system 24. Although not shown, when the light ray 50 is irradiated to the region 74b of the retina 74, the light ray 50 enters the eye 70 from the +X region, and the corneal reflected light ray 56 reflected by the cornea 75 is reflected toward the -X region. The corneal reflected light ray 56 passes through the optical components 22 and 21, then bends toward the +X region by the optical component 23, and enters the pseudo-eye optical system 24.

13(a), 13(b), 14(b), and 14(c), the cornea 75 has a convex curved shape, so the corneal reflected light 56 is reflected by a convex curved mirror. Since the light ray 50 is incident on the cornea 75 as approximately parallel light, the corneal reflected light ray 56 reflected by the cornea 75 becomes diffuse light. The corneal reflected light ray 56 is converted from diffuse light to approximately parallel light by the optical component 22, and then converted from approximately parallel light to convergent light by the optical component 23. The corneal reflected light ray 56 is converted into convergent light by the optical component 23, and is focused at a focal point 57 in front of the pseudo-eye optical system 24. The pseudo-eye optical system 24 is disposed at a convergence point 53 (the convergence points 52 and 53 are located at the positions shown in FIG. 2) that is approximately conjugate with the convergence point 52 at which the multiple light rays 50 converge near the pupil 71, so that the corneal reflected light ray 56 is focused in front of the pseudo-eye optical system 24. In other words, when the corneal reflected light ray 56 is extended into the eye 70, the corneal reflected light ray 56 has a focal point between the convergence point 52 and the cornea 75, and this focal point and the focal point 57 are approximately conjugate positions.

As shown in Figures 12(a) to 13(b), when the light ray 50 is irradiated to the area 74a of the retina 74, the retinal reflected light ray 51 and the corneal reflected light ray 56 travel different paths and enter the pseudo-eye optical system 24. The same is true when the light ray 50 is irradiated to the area 74b of the retina 74. Here, an imaginary plane passing through the focal point 57 of the corneal reflected light ray 56 is taken as an imaginary plane 58. In the imaginary plane 58, the retinal reflected light ray 51 is located approximately in the -X area from the origin of the X axis, whereas the corneal reflected light ray 56 is located approximately in the +X area from the origin of the X axis. Therefore, an example of suppressing the effect of the corneal reflected light ray 56 on the fundus image by utilizing such a difference will be described below.

Fig. 15 is a block diagram of a fundus imaging device according to Example 6. Referring to Fig. 15, the fundus imaging device 600 of Example 6 further includes a drive control unit 34 and a drive mechanism 95, in comparison with the fundus imaging device 100 of Example 1 in Fig. 1. The drive control unit 34 outputs a control signal to the drive mechanism 95 when the image control unit 31 outputs a control signal for fundus imaging to the drive circuit 14. The drive mechanism 95 drives a light shielding plate (see Figs. 16(a) to 16(d) described later) provided in the optical system 13 based on the control signal of the drive control unit 34. The drive mechanism 95 includes, for example, a stepping motor. The other configurations are the same as those in Fig. 1 of Example 1, and therefore will not be described.

16(a) to 16(d) are diagrams showing the optical system of the fundus imaging device according to the sixth embodiment. 16(a) and 16(b) show the retinal reflected light ray 51 and the corneal reflected light ray 56 when the light ray 50 is incident on the region 74a of the retina 74, and 16(c) and 16(d) show the retinal reflected light ray 51 and the corneal reflected light ray 56 when the light ray 50 is incident on the region 74b of the retina 74. 16(a) to 16(d) show the fundus imaging device as seen from above, and the projector 16 is omitted for clarity.

Referring to Fig. 16(a) to Fig. 16(d), in the fundus imaging device 600 of the sixth embodiment, a light shielding plate 96 that can move in the ±X direction as shown by the arrow 92 is disposed between the optical component 23 and the pseudo-eye optical system 24, and closer to the pseudo-eye optical system 24 than the center between the optical component 23 and the pseudo-eye optical system 24. For example, the light shielding plate 96 is disposed on the virtual plane 58 that passes through the focal point 57 of the corneal reflected light ray 56, as shown in Fig. 12(a) to Fig. 13(b). The light shielding plate 96 is driven in the ±X direction of the arrow 92 by a driving mechanism 95. The other configurations are the same as those of the first embodiment, and therefore will not be described.

16(a) and 16(b), when the light ray 50 is incident on the region 74a of the retina 74, the light shielding plate 96 moves to a first position where it shields all of the corneal reflected light rays 56 and passes a part of each of the retinal reflected light rays 51. Here, as shown in FIG. 12(a) to FIG. 13(b), in the virtual plane 58, the multiple corneal reflected light rays 56 are focused, whereas the multiple retinal reflected light rays 51 are generally converged and each of the multiple retinal reflected light rays 51 is approximately parallel light having approximately the same size as when the light ray 50 is incident on the cornea 75. The diameter of the retinal reflected light ray 51 in the virtual plane 58 is about 0.8 mm to 1.65 mm. If the multiple corneal reflected light rays 56 are all shielded by the light shielding plate 96, the tip of the light shielding plate 96 will slightly protrude from the origin of the X-axis into the -X region. Therefore, the retinal reflected light ray 51 will be split in half by the light shielding plate 96.

Figure 17 is a diagram showing an example of a retinal reflected light ray that has a half-split shape. Since the diameter of the retinal reflected light ray 51 on the virtual plane 58 is about 0.8 mm to 1.65 mm, and the amount by which the light shielding plate 96 protrudes from the origin into the -X region is about 10 μm to 50 μm, even if the retinal reflected light ray 51 has a half-split shape due to the light shielding plate 96, there is no problem with detection by the photodetector 40. Therefore, the multiple corneal reflected light rays 56 reflected by the cornea 75 are shielded by the light shielding plate 96 and are prevented from entering the photodetector 40, and each of the multiple retinal reflected light rays 51 reflected by the region 74a of the retina 74 passes through the light shielding plate 96 and is detected by the photodetector 40.

16(c) and 16(d), when the light ray 50 is incident on the region 74b of the retina 74, the light shielding plate 96 moves to a second position where it shields all of the corneal reflected light rays 56 and passes a portion of each of the retinal reflected light rays 51. As a result, the corneal reflected light rays 56 reflected by the cornea 75 are shielded by the light shielding plate 96 and prevented from entering the photodetector 40, and a portion of each of the retinal reflected light rays 51 reflected by the region 74b of the retina 74 passes through the light shielding plate 96 and is detected by the photodetector 40.

Figure 18 is a flowchart showing an example of fundus photography processing. With reference to Figure 18, the drive control unit 34 controls the drive of the drive mechanism 95 to move the light shielding plate 96 to the first position shown in Figures 16(a) and 16(b) (step S30). Next, the image control unit 31 controls the drive of the light source 11 and the scanning unit 12 to emit light beams 50 for fundus photography from the projector 16 to irradiate only the area 74a of the areas 74a and 74b into which the retina 74 is divided (step S32). Here, irradiating the light beams 50 only to the area 74a can be achieved by, for example, emitting the light beams 50 from the light source 11 only when the scanning unit 12 scans the area 74a in the scanning of the light beams 50 on the retina 74 described in Figure 4. As a result, as shown in Figures 16(a) and 16(b), a portion of each of the multiple retinal reflection light rays 51 reflected by the region 74a of the retina 74 is incident on the photodetector 40 and detected, but all of the multiple corneal reflection light rays 56 reflected by the cornea 75 are blocked by the light blocking plate 96 and are prevented from entering the photodetector 40. Note that the order of steps S30 and S32 may be reversed.

Next, the signal processing unit 32 acquires the output signal of the photodetector 40 (step S34). Next, the image generating unit 33 generates a first image of the fundus based on the result of the signal processing unit 32 processing the output signal of the photodetector 40 (step S36). The first image is a fundus image of the region 74a of the retina 74.

Next, the drive control unit 34 controls the drive of the drive mechanism 95 to move the light shielding plate 96 to the second position shown in Figures 16(c) and 16(d) (step S38). Next, the image control unit 31 controls the drive of the light source 11 and the scanning unit 12 to emit light beams 50 for fundus photography from the projector 16 to irradiate only the area 74b of the areas 74a and 74b of the retina 74 (step S40). To irradiate only the area 74b with the light beams 50, the light beams 50 may be emitted from the light source 11 only when the scanning unit 12 scans the area 74b, for example, in the same way as when the light beams 50 are irradiated only to the area 74a. As a result, as shown in Figures 16(c) and 16(d), a portion of each of the multiple retinal reflected light rays 51 reflected by the region 74b of the retina 74 is incident on the photodetector 40 and detected, but all of the multiple corneal reflected light rays 56 reflected by the cornea 75 are blocked by the light blocking plate 96 and are prevented from entering the photodetector 40. Note that the order of steps S38 and S40 may be reversed.

Next, the signal processing unit 32 acquires the output signal of the photodetector 40 (step S42). Next, the image generating unit 33 generates a second image of the fundus based on the result of the signal processing unit 32 processing the output signal of the photodetector 40 (step S44). The second image is a fundus image of the region 74b of the retina 74.

Next, the image generating unit 33 synthesizes the first image generated in step S36 and the second image generated in step S44 to generate a fundus image of the entire retina 74 (step S46). The display unit 41 displays the fundus image generated by the image generating unit 33 (step S48).

According to the sixth embodiment, as shown in Figs. 16(a) to 16(d), when the light beam 50 is irradiated to the region 74a, the image control unit 31 (irradiation region adjustment unit) does not irradiate the region 74b of the two regions 74a and 74b obtained by dividing the retina 74 into two regions on the left and right sides with respect to the center, as shown in Figs. 16(a) to 16(d), when the light beam 50 is irradiated to the region 74a, the image control unit 31 (irradiation region adjustment unit) does not irradiate the region 74b, and when the light beam 50 is irradiated to the region 74b, the image control unit 31 does not irradiate the region 74a. A light shielding plate 96 (light shielding member) is movably arranged between the optical component 23 and the pseudo-eye optical system 24. In other words, the light shielding plate 96 is movably arranged between the optical component 23 and the convergence point 53. The light shielding plate 96 is moved by the driving mechanism 95 (see Fig. 15). When the light beam 50 is irradiated only to the region 74a, as shown in Figs. 16(a) and 16(b), the driving mechanism 95 moves the light shielding plate 96 to a first position where the corneal reflection light beam 56 is shielded and the retinal reflection light beam 51 passes through. As shown in FIG. 16(c) and FIG. 16(d), when the light ray 50 is irradiated only to the region 74b, the light shielding plate 96 is moved to a second position where the corneal reflected light ray 56 is shielded and the retinal reflected light ray 51 passes through. The image generating unit 33 generates an image based on the output signal of the photodetector 40 in each of the regions 74a and 74b where the light ray 50 is irradiated, and generates a fundus image by combining these two images. This reduces the effect of the corneal reflected light ray 56 on the fundus image, and a good fundus image can be obtained. In the sixth embodiment, the retina 74 is divided into two parts, left and right, but this is not limited to this case. Other cases may be used as long as the retina 74 is divided into two parts with respect to the center of the retina 74, such as dividing the retina 74 into two parts above and below.

In the sixth embodiment, the image control unit 31 performs the function of the irradiation area adjustment unit that does not irradiate the area 74b when the light beam 50 is irradiated to the area 74a out of the areas 74a and 74b, and does not irradiate the area 74a when the light beam 50 is irradiated to the area 74b, but this is not limited to this case. Figs. 19(a) and 19(b) are diagrams showing the optical system of the fundus imaging device according to the first modification of the sixth embodiment. Referring to Figs. 19(a) and 19(b), the light shielding plate 97 arranged between the optical components 21 and 22 so as to be movable in the ±X direction may function as the irradiation area adjustment unit. That is, the light shielding plate 97 may be moved to a first position so that the light beam 50 is irradiated only to the area 74a, and the light shielding plate 97 may be moved to a second position so that the light beam 50 is irradiated only to the area 74b. The light shielding plate 97 may be driven by a driving mechanism 95. The light shielding plate 97 is not limited to being placed between the optical components 21 and 22, but may be placed between the optical components 19 and 21, or between the optical component 22 and the eye 70.

The radius of curvature of the surface of the cornea 75 varies from person to person, with a distribution of about 7.8 mm ± 1.0 mm. If the radius of curvature of the cornea 75 differs, the position of the focal point 57 of the corneal reflected light ray 56 changes. Figures 20(a) to 20(c) are diagrams showing the change in the position of the focal point of the corneal reflected light ray due to the difference in the radius of curvature of the cornea. In Figures 20(b) and 20(c), the virtual plane 58 in Figure 20(a) is shown by a dashed line. Figure 20(a) shows the case where the radius of curvature of the cornea 75 is 7.8 mm. If the radius of curvature becomes smaller than 7.8 mm, the focal point 57 of the corneal reflected light ray 56, i.e., the virtual plane 58, approaches the pseudo-eye optical system 24, as shown in Figure 20(b). Conversely, when the radius of curvature is greater than 7.8 mm, as shown in FIG. 20(c), the focal point 57 of the corneal reflected light ray 56, i.e., the virtual plane 58, moves away from the pseudo-eye optical system 24. For example, when the radius of curvature is 6.8 mm, the position of the focal point 57 (position of the virtual plane 58) is approximately 0.5 mm closer to the pseudo-eye optical system 24 than when the radius of curvature is 7.8 mm. When the radius of curvature is 8.8 mm, the position of the focal point 57 (position of the virtual plane 58) is approximately 0.5 mm farther from the pseudo-eye optical system 24 than when the radius of curvature is 7.8 mm.

When the light shielding plate 96 is positioned offset from the virtual plane 58, the greater the offset, the larger the beam diameter of the corneal reflected light ray 56 at the light shielding plate 96. That is, as shown in FIG. 16(b) and FIG. 16(d), when the corneal reflected light ray 56 is shielded by the light shielding plate 96, the amount of protrusion of the tip of the light shielding plate 96 into the -X region or +X region increases, and as a result, the beam diameter of the retinal reflected light ray 51 passing through the light shielding plate 96 becomes smaller. Therefore, it is preferable that the light shielding plate 96 is positioned on the virtual plane 58 or near the virtual plane 58. That is, it is preferable that the light shielding plate 96 is positioned at the focal point 57 or near the focal point 57 where the corneal reflected light ray 56 is focused in front of the pseudo-eye optical system 24 (i.e., in front of the convergence point 53). Near the focal point 57 means, for example, within the range of the distance from the focal point 57 to the focal point 57 and the convergence point 53.

20(a) to 20(c), since the position of the focal point 57 of the corneal reflected light ray 56 changes depending on the radius of curvature of the cornea 75, it is preferable that the driving mechanism 95 is capable of moving the light blocking plate 96 not only in the ±X direction but also in the ±Z direction. In other words, it is preferable that the light blocking plate 96 is capable of moving in a first direction in which the corneal reflected light ray 56 is incident on the light blocking plate 96 and in a second direction intersecting the first direction. Note that the driving mechanism 95 may drive the light blocking plate 96 and the pseudo-eye optical system 24 as a single unit in the ±Z direction.

In Example 6, a case where a two-dimensionally scanned light beam 50 is emitted from the projector 16 is shown as an example, but light that is not two-dimensionally scanned (imaging light for fundus photography) may also be emitted. Even in this case, by using an optical system including optical components 19, 21, 22, and 23, and a light shielding plate 96, the effect of the reflected light of the imaging light reflected by the cornea 75 on the fundus image can be suppressed, and a good fundus image can be obtained. When imaging light that is not two-dimensionally scanned is emitted, the optical system does not need to be equipped with a pseudo-eye optical system 24.

Figure 21 is a side view showing an example in which the light shielding plate arranged on the virtual plane has a U-shape. In Figure 21, the retinal reflected light ray 51 and the corneal reflected light ray 56 reflected by the retina 74 and the cornea 75 at different times are illustrated, and the corneal reflected light ray 56 is hatched to clarify the drawing (the same applies to Figures 22(a) and 22(b) described below). As shown in Figure 21, the size of the corneal reflected light ray 56 on the light shielding plate 96a arranged on the virtual plane 58 is smallest at the corneal reflected light ray 56 located at the center, and gradually increases as it moves away from the center due to the influence of aberrations in the optical system. In order to shield the expanded corneal reflected light ray 56, it is preferable that the light shielding plate 96a be made wider on the peripheral side.

Figures 22(a) and 22(b) are diagrams showing problems that arise when a flat light shielding plate is used to shield the corneal reflected light beam. As in Figure 22(a), if a flat light shielding plate 96 is placed in a position to shield the corneal reflected light beam 56 located in the center, it may not be possible to shield the enlarged corneal reflected light beam 56 located away from the center. As in Figure 22(b), if the light shielding plate 96 is made large enough to shield the enlarged corneal reflected light beam 56, the amount of retinal reflected light beam 51 blocked will increase, resulting in a dimmed fundus image.

21, the light shielding plate 96a is concave at the central portion corresponding to the corneal reflected light ray 56 and protrudes from the peripheral portion away from the central portion, thereby blocking the expanded corneal reflected light ray 56 at the periphery and minimizing the dimming of the retinal reflected light ray 51. The movement of the light shielding plate 96a from the first position to the second position as described in FIG. 16(a) to FIG. 16(d) can be achieved by the driving mechanism 95 rotating the light shielding plate 96a 180°.

In the fundus imaging devices of Examples 1 to 6, the pseudo-eye optical system 24 and the photodetector 40 have the same functions as a general digital camera if the pseudo-eye optical system 24 is a camera lens and the photodetector 40 is an image sensor, so the pseudo-eye optical system 24, the photodetector 40, and the image generating unit 33 can be replaced with a digital camera. Here, when replacing with a digital camera in Example 6, attention may be required for the positional relationship between the camera lens and the light shielding plate 96 or 96a. That is, in order to improve the optical characteristics of the camera lens, the focal point 57 of the optical system of the fundus imaging device of Example 6 may be inside the camera lens by combining multiple lenses, etc. In this case, the camera lens and the light shielding plate 96 or 96a interfere with each other. On the other hand, the focal point 57 of the camera lens used in a smartphone or the like is often outside the camera lens, and it is preferable to use such a camera lens for the fundus imaging device of Example 6, as it is compact. Furthermore, as described in Example 1, if the projector 16 is a general-purpose projector, a fundus imaging device can be configured using a digital camera and the general-purpose projector.

In Example 6, a configuration and method for reducing the effect of corneal reflected light 56 was described. In Example 7, a different configuration and method for reducing the effect of corneal reflected light 56 will be described.

Fig. 23 is a diagram showing the optical system of a fundus imaging device 700 according to Example 7. Referring to Fig. 23, in the fundus imaging device 700, a polarizing plate 81 and an optical component 21b are arranged in the optical path of the multiple light beams 50 emitted from the projector 16. The polarizing plate 81 may be provided between the attenuation filter 20 and the optical component 21b, or between the attenuation filter 20 and the optical component 19.

When the projector 16 is a laser scanning projector, the emitted light beam 50 is a linearly polarized laser beam. The polarizing plate 81 is a polarizing filter that adjusts the linearly polarized light beam 50 so that it is transmitted as an S wave corresponding to the optical characteristics of the optical component 21b. The polarizing plate 81 converts the linearly polarized light beam 50 emitted from the projector 16 into an S wave that vibrates perpendicular to the normal to the reflection surface of the optical component 21b and the plane containing the incident beam, and makes it incident on the optical component 21b. The optical component 21b is a polarizing beam splitter that reflects S waves and transmits other than S waves, and reflects the S wave light beam 50 that has passed through the polarizing plate 81. The optical characteristics of the polarizing plate 81 and the optical component 21b, including their orientation and/or positional relationship, are adjusted so that the optical component 21b efficiently reflects the S wave.

The S-wave light ray 50 passes through the optical component 22 and is irradiated onto the cornea 75 and retina 74. The cornea 75 transmits most of the irradiated light ray 50 and reflects some of it, but because the cornea 75 is an almost uniform sphere, the irradiated S-wave light ray 50 remains an S-wave and is partially reflected. The S-wave light ray 50 irradiated onto the retina 74 is reflected as randomly polarized light, rather than being reflected with a uniform polarization, because the surface of the retina 74 is minutely uneven.

The reflected light ray of the S wave reflected by the cornea 75 and the reflected light ray of the randomly polarized light reflected by the retina 74 pass through the optical component 22. The reflected light ray of the S wave reflected by the cornea 75 is reflected by the optical component 21b and does not pass through the optical component 21b, so it does not reach the photodetector 40. On the other hand, the reflected light ray 51 other than the randomly polarized S wave reflected by the retina 74 passes through the optical component 21b and reaches the photodetector 40. As a result, the reflected light ray of the S wave reflected by the cornea 75 is not detected by the photodetector 40, and the reflected light ray 51 other than the randomly polarized S wave reflected by the retina 74 is detected by the photodetector 40. Therefore, the influence of the light component reflected by the cornea 75 can be reduced, and the reflected light ray 51 reflected by the retina 74 can be mainly detected by the photodetector 40, and the S/N ratio of the fundus image can be improved.

Here, the polarizing plate 81 may be a polarizing filter adjusted to transmit the P wave of the linearly polarized light beam 50, and the optical component 21b may be a polarizing beam splitter that reflects the P wave transmitted through the polarizing plate 81 and transmits other waves, and the same effect can be obtained by the same operation as above. Note that the projector 16 is a laser scanning projector that outputs linearly polarized laser light, but even if a projector that emits unpolarized light by illumination light rather than laser scanning is used, it can be used by adjusting the optical characteristics of the polarizing plate 81 and the optical component 21b to correspond to unpolarized light. For example, when the projector 16 emits unpolarized light, the polarizing plate 81 may transmit the unpolarized light as vertically polarized light.

In the fundus imaging devices of Examples 1 to 7, in addition to photographing the fundus, a visual function test may be performed by emitting a two-dimensionally scanned light beam from the projector 16 to project a test target for testing visual function (e.g., visual field). This allows both fundus image acquisition and visual function testing to be performed using a single projector 16.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims.

LIST OF SYMBOLS 10 Projection unit 11 Light source 12 Scanning unit 13 Optical system 14 Driving circuit 15 Input circuit 16 Projector 17 Collimating lens 18 Mirror 19 Optical components 20 Attenuation filter 21, 21a, 21b, 22, 22a, 23 Optical components 24 Pseudo-eye optical system 24a Convex lens 24b Concave lens 24c Convex lens 25 1/4 wavelength plate 26 Light source 27, 28 Optical components 29 Housing 30 Control unit 31 Image control unit 32 Signal processing unit 33 Image generating unit 34 Driving control unit 40 Photodetector 40a Detection surface 41 Display unit 50 Light ray 51 Reflected light ray 52, 53 Convergence point 54 Background light 56 Reflected light ray 57 Focus point 58 Virtual plane 70 Eye 71 Pupil 72 Lens 73 Vitreous body 74 Retina 74a, 74b Area 75 Cornea 81 Polarizing plate 90 Housing 91 Lens barrel 95 Driving mechanism 96, 96a, 97 Light shielding plate 100, 200, 300, 400, 500, 600, 700 Fundus imaging device

Claims (9)

A light source that emits a light beam;
A scanning unit that scans the light beam two-dimensionally;
a first optical component that converges the plurality of light beams scanned by the scanning unit and emitted at different times to a first convergence point near a pupil of the subject and then irradiates the retina of the subject;
a second optical component that converges a plurality of reflected light beams, which are reflected by a retina of the subject and transmitted through the first optical component, to a second convergence point;
an optical system disposed at the second convergence point and configured to convert each of the plurality of reflected light beams into convergent light;
a photodetector for detecting the plurality of reflected light beams transmitted through the optical system;
an image generating unit that generates a fundus image based on an output signal of the photodetector ,
The scanning unit and the first convergence point are in a substantially conjugate positional relationship . A light source that emits a light beam;
A scanning unit that scans the light beam two-dimensionally;
a first optical component that converges the plurality of light beams scanned by the scanning unit and emitted at different times to a first convergence point near a pupil of the subject and then irradiates the retina of the subject;
a second optical component that converges a plurality of reflected light beams, which are reflected by a retina of the subject and transmitted through the first optical component, to a second convergence point;
an optical system disposed at the second convergence point and configured to convert each of the plurality of reflected light beams into convergent light;
a photodetector for detecting the plurality of reflected light beams transmitted through the optical system;
an image generating unit that generates a fundus image based on an output signal of the photodetector,
A fundus photography apparatus, wherein the beam diameter of the light beam incident on the subject's cornea is 0.8 mm or more and 1.65 mm or less. A projector, a projection unit, and an image generating unit are provided,
The projector includes:
A light source that emits a light beam;
A scanning unit that scans the light beam two-dimensionally;
an emission unit that emits the scanned light beam,
The projection unit is
a first optical component that converges the plurality of light beams emitted from the projector at different times to a first convergence point near a pupil of the subject and then irradiates the light beam on a retina of the subject;
a second optical component that converges a plurality of reflected light beams, which are reflected by a retina of the subject and transmitted through the first optical component, to a second convergence point;
an optical system disposed at the second convergence point and configured to convert each of the plurality of reflected light beams into convergent light;
a photodetector that detects the plurality of reflected light beams that have passed through the optical system;
The image generating unit generates a fundus image based on an output signal from the photodetector ,
The scanning unit and the first convergence point are in a substantially conjugate positional relationship . A projector, a projection unit, and an image generating unit are provided,
The projector includes:
A light source that emits a light beam;
A scanning unit that scans the light beam two-dimensionally;
an emission unit that emits the scanned light beam,
The projection unit is
a first optical component that converges the plurality of light beams emitted from the projector at different times to a first convergence point near a pupil of the subject and then irradiates the light beam on a retina of the subject;
a second optical component that converges a plurality of reflected light beams, which are reflected by a retina of the subject and transmitted through the first optical component, to a second convergence point;
an optical system disposed at the second convergence point and configured to convert each of the plurality of reflected light beams into convergent light;
a photodetector that detects the plurality of reflected light beams that have passed through the optical system;
The image generating unit generates a fundus image based on an output signal from the photodetector,
A fundus photography apparatus, wherein the beam diameter of the light beam incident on the subject's cornea is 0.8 mm or more and 1.65 mm or less. A projector, a projection unit, and an image generating unit are provided,
The projector includes:
A light source that emits a light beam;
A scanning unit that scans the light beam two-dimensionally;
an emission unit that emits the scanned light beam,
The projection unit is
a first optical component that converges the plurality of light beams emitted from the projector at different times to a first convergence point near a pupil of the subject and then irradiates the light beam on a retina of the subject;
a second optical component that converges a plurality of reflected light beams that are reflected by a retina of the subject and transmitted through the first optical component to a second convergence point;
an optical system disposed at the second convergence point and configured to convert each of the plurality of reflected light beams into convergent light;
a photodetector that detects the plurality of reflected light beams that have passed through the optical system;
The image generating unit generates a fundus image based on an output signal from the photodetector,
The projection unit has a detachable part that is detachable from the projector. the first convergence point and the second convergence point are located at substantially conjugate positions;
The fundus imaging apparatus according to claim 1 , wherein the subject's retina and the photodetector are located at substantially conjugate positions. the first optical component converges the plurality of light beams to the first convergence point and converts each of the plurality of light beams from diffuse light to substantially parallel light,
the second optical component converges the reflected light beams to the second convergence point and converts each of the reflected light beams from diffuse light to substantially parallel light,
The fundus imaging apparatus according to claim 1 , wherein the optical system converts each of the plurality of reflected light beams from approximately parallel light to convergent light. The fundus imaging apparatus according to claim 1 , wherein the plurality of reflected light beams are focused in front of the second optical component, and become diffused light to be incident on the second optical component. 9. The fundus imaging apparatus according to claim 1, further comprising a third optical component disposed between the second optical component and the optical system, the third optical component bending the reflected light beams.

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