Ophthalmic device

Abstract

This ophthalmic device comprises: an illumination system that irradiates a part of an observation target area of an eye being examined with illumination light; an optical scanner that deflects the illumination light, with which the observation target area is irradiated from the illumination system, and moves an illumination region of the illumination light within the observation target area; and an imaging system that receives return light from the illumination region moving within the observation target area according to the deflection of the illumination light while the optical scanner deflects the illumination light. The distortion aberration of one of the illumination system and the imaging system is a barrel type, and the distortion aberration of the other of the illumination system and the imaging system is a pincushion type.

Description

Ophthalmological apparatus

[0001] The present disclosure relates to an ophthalmological apparatus comprising an illumination optical system and a light-receiving optical system.

[0002] As an ophthalmological apparatus, a slit-scan fundus camera that captures images of the fundus of a subject's eye is known (see Patent Document 1: Japanese Unexamined Patent Publication No. 2022-157209). The fundus camera described in Patent Document 1 uses an optical scanner to deflect slit light (illumination light) irradiated onto the fundus, while capturing return light from the illumination area of the slit light moving within the fundus with a CMOS (Complementary Metal Oxide Semiconductor) image sensor having a rolling shutter function. The image sensor continuously performs light reception (imaging) of the return light while causing the light-receiving region that receives the return light via the rolling shutter to follow the incident region of the return light moving within the light-receiving surface of the image sensor. In such slit scan photography, since the illumination range of the slit light on the fundus is small, the influence of flare (e.g., lens scattering) occurring in the optical system of the fundus camera and the subject's eye is suppressed. As a result, a fundus image, which is a captured image of the fundus with suppressed artifacts, can be obtained.

[0003] Furthermore, in the ophthalmological apparatus described in Patent Document 1, the distortion aberration of an illumination system that irradiates slit light onto the fundus and the distortion aberration of an imaging system (light-receiving system) that receives return light from the fundus irradiated with the slit light are set to the same type. Accordingly, distortion of the return light caused by the distortion aberration of the illumination system can be reduced by the imaging system, so that deterioration of the fundus image is suppressed.

[0004] In slit scan photography, it is common that an optical scanner deflects the slit light at a constant speed (linearly), and a rolling shutter displaces the light-receiving region within the light-receiving surface of the image sensor at a constant speed (linearly).

[0005] In this case, the inventors have found that if the distortion aberration of the light-receiving system and the imaging system are of the same type, as described in Patent Document 1, when the slit light is deflected at a constant speed by the optical scanner, the movement speed of the incident region of the reflected light within the light-receiving surface of the image sensor will not be constant, and a discrepancy will occur between the movement speed of the incident region and the movement speed of the light-receiving region. In this case, a discrepancy occurs between the incident region and the light-receiving region of the reflected light within the light-receiving surface, causing the image to darken. For this reason, in the ophthalmic device described in Patent Document 1, it was necessary to widen the width of the light-receiving region so that the incident region would be included within the light-receiving region even if there was a discrepancy between the movement speed of the incident region and the movement speed of the light-receiving region. As a result, there is a risk that the signal-to-noise ratio (S / N ratio) of the fundus image may deteriorate, or the effects of ghosting and flare may increase, leading to deterioration of the fundus image.

[0006] This disclosure is made in view of these circumstances and aims to provide an ophthalmic device that can reduce the degradation of the observed image of the observed area by narrowing the width of the light-receiving area compared to conventional devices.

[0007] An ophthalmic apparatus for achieving the objectives of this disclosure comprises: an illumination system that irradiates illumination light onto a portion of the area to be observed of the eye under examination; an optical scanner that deflects the illumination light irradiated from the illumination system onto the area to be observed to move the illumination area of ​​the illumination light within the area to be observed; and an imaging system that receives the reflected light from the illumination area that moves within the area to be observed in accordance with the deflection of the illumination light while the optical scanner is deflecting the illumination light, wherein the distortion aberration of one of the illumination system and imaging system is barrel-shaped, and the distortion aberration of the other of the illumination system and imaging system is pincushion-shaped.

[0008] The ophthalmic device disclosed herein can reduce the degradation of the observed image of the area being observed by narrowing the width of the light-receiving area compared to conventional devices.

[0009] This is a schematic diagram of the fundus camera. This is a functional block diagram of the control device. This is an explanatory diagram comparing the fundus (see reference numeral 3A) and the light-receiving surface of the image sensor (see reference numeral 3B) during slit scan imaging. This is an explanatory diagram showing an example of a fundus image generated by the image generation unit. This is an explanatory diagram to explain the distortion of the incident region caused by barrel distortion aberration of the imaging system. This is an explanatory diagram to explain the distortion of the incident region caused by pincushion distortion aberration of the imaging system. This is a graph showing the ratio of the imaging magnification at the periphery of the field of view to the imaging magnification at the center of the field of view in the imaging system, that is, the difference in image size at the periphery of the field of view compared to the center of the field of view. This is a graph showing the difference in the scanning speed of the illumination light at the periphery of the field of view to the scanning speed of the illumination light at the center of the field of view in the illumination system. This is an explanatory diagram showing the combination of distortion aberration of the illumination system and distortion aberration of the imaging system. This is a diagram comparing the width W1 of the light-receiving region in the comparative example (see reference numeral XA) with the width W1 of the light-receiving region in this embodiment (see reference numeral XB).

[0010] [Overall Configuration of Fundus Camera] Figure 1 is a schematic diagram of a fundus camera 10 corresponding to the ophthalmic device of this disclosure. Of the mutually orthogonal XYZ directions in the figure, the X direction is the left-right direction relative to the subject (the interpupillary distance direction of the subject eye E), the Y direction is the up-down direction, and the Z direction is the front-back direction (also called the working distance direction) parallel to the forward direction approaching the subject and the back direction moving away from the subject.

[0011] As shown in Figure 1, the fundus camera 10 takes a slit scan image of the fundus Ef of the eye E under examination (hereinafter referred to as slit scan imaging). The fundus camera 10 comprises a camera head 12 (also called the main body of the device), an operating unit 14, a display unit 16, and a control device 18.

[0012] The camera head 12 is equipped with various optical systems necessary for slit scan imaging, as will be described in more detail later. Although not shown in the diagram, the camera head 12 is held so as to be able to move relative to the XYZ direction by a drive mechanism (not shown). This allows the camera head 12 to move relative to the eye E in the XYZ direction, thus enabling alignment of the camera head 12 with respect to the eye E.

[0013] The control unit 14 receives input for various operations of the fundus camera 10, such as the operation to start slit scan imaging, the operation to move the camera head 12 in the XYZ directions, and the operation to set the fundus camera 10.

[0014] The display unit 16 uses various known displays, such as an LCD (Liquid Crystal Display). This display unit 16 displays the fundus image D, which is an observation image (frontal image) of the fundus Ef generated by the control device 18 described later, as well as various setting screens, etc. If the display unit 16 is a touch panel type LCD, the display surface of this display unit 16 can be made to function as the operation unit 14.

[0015] The control device 18 is a computer or other arithmetic processing unit that performs various calculation and control processes. The camera head 12, the operation unit 14, and the display unit 16 are connected to this control device 18. Based on the operation instructions input to the operation unit 14, the control device 18 comprehensively controls the operation of each part of the camera head 12 and the display unit 16. For example, the control device 18 performs various controls and processes, including the alignment of the camera head 12, slit scan imaging of the fundus Ef by the camera head 12, and the generation and display of the fundus image D.

[0016] [Camera head configuration] The camera head 12 comprises an illumination system 20, an optical scanner 30, and an imaging system 40 (also called a light receiving system).

[0017] The illumination system 20 irradiates a portion of the fundus Ef with illumination light LS (slit light) via the optical scanner 30, which will be described later. This illumination system 20 comprises a light source 22, an aperture 24, a slit aperture diaphragm 26, an illumination system lens 28, a lens 31, an optical path splitting material 34, and an objective lens 38. The aperture 24, the optical scanner 30, the optical path splitting material 34, and the anterior segment Ea (pupil, etc.) of the eye E under examination are in an optically conjugate relationship.

[0018] The aperture 24 includes, but is not limited to, apertures (e.g., iris apertures or anterior lens apertures) that are optically conjugate or nearly optically conjugate to the anterior segment Ea of the eye E under examination. This aperture 24 is a light-shielding member having a pair of symmetrical openings about the central axis of the light source 22. The number and arrangement of the openings of the aperture 24 are not particularly limited, as long as multiple openings are provided at positions eccentric with respect to the central axis of the light source 22. The illumination light L that has passed through the aperture 24 is incident on the slit aperture aperture 26.

[0019] The slit aperture diaphragm 26 generates illumination light LS parallel to the X direction (corresponding to the first direction in this disclosure) from the illumination light L incident from the aperture 24, and emits this illumination light LS toward the illumination system lens 28. When focused, the illumination light LS becomes a slit shape (slit light) parallel to the X direction at the fundus position and the fundus conjugate position. The direction of the slit light is not particularly limited as long as it is perpendicular to the optical axis of the objective lens 38 (illumination system 20). The slit aperture diaphragm 26 is also provided to be movable along the optical path of the illumination light LS by an actuator (not shown). By moving the slit aperture diaphragm 26, the illumination system 20 can be focused on the fundus Ef.

[0020] The illumination lens 28 is composed of one or more lenses and emits illumination light LS incident from the slit aperture 26 toward the optical scanner 30. Lens 31 emits the illumination light LS reflected by the optical scanner 30 toward the optical path splitting material 34. Lens 31 creates an optical conjugate relationship between the optical scanner 30 and the optical path splitting material 34. The optical path splitting material 34 and the objective lens 38 will be described later.

[0021] Furthermore, a projector capable of emitting illumination light LS may be used as the illumination system 20. Examples of such projectors include LCD projectors, LCOS (Liquid crystal on silicon) projectors using reflective liquid crystal panels, and DMD (Digital Mirror Device) projectors. In this case, the optical scanning performed by the optical scanner 30 described later may be simulated by changing the pattern of the illumination light LS emitted from the projector.

[0022] The optical scanner 30 is a deflection mechanism capable of one-dimensionally deflecting (scanning) illumination light LS, such as a galvanometer mirror, resonant mirror, polygon mirror, and MEMS (Micro Electro Mechanical Systems), and is positioned at the intersection of the optical axis of the illumination system lens 28 and the optical axis of lens 31. This optical scanner 30 reflects the illumination light LS incident from the illumination system lens 28 toward lens 31 and is capable of deflecting this illumination light LS.

[0023] The polarization direction and deflection angle of the illumination light LS from the optical scanner 30 are controlled by the control device 18. When slit scan imaging is performed, the optical scanner 30 deflects the illumination light LS in a direction perpendicular to both the optical axis of the objective lens 38 and the slit light, in this case the Y direction (corresponding to the second direction in this disclosure).

[0024] The optical path splitting material 34 reflects the illumination light LS incident from the lens 31 and directs it toward the objective lens 38, and also allows the reflected light LB, described later, incident from the objective lens 38, to pass through and exit toward the focusing optical system 36. Various splitters can be used as the optical path splitting material 34, as long as they can split the illumination light LS and the reflected light LB, reflecting the illumination light LS toward the objective lens 38 and directing the reflected light LB toward the focusing optical system 36.

[0025] The objective lens 38 (corresponding to the objective optical system of this disclosure) illuminates a portion of the fundus Ef through the anterior segment Ea (pupil) with illumination light LS reflected by the optical path splitting material 34. At this time, the illumination light LS is deflected in the Y direction by the optical scanner 30 described above, so that the fundus Ef is scanned in the Y direction by illumination light LS (slit light) parallel to the X direction. While the illumination light LS is being deflected in the Y direction, the reflected light LB from the fundus Ef of the eye E that has been illuminated by the illumination light LS enters the focus optical system 36 through the objective lens 38 and the optical path splitting material 34. Note that a concave mirror may be used as the objective optical system of this disclosure instead of the objective lens 38.

[0026] The imaging system 40 comprises an objective lens 38, an optical path splitting material 34, a focusing optical system 36, an imaging system lens 42, and a CMOS type image sensor 44 corresponding to the detector of this disclosure.

[0027] The focusing optical system 36 includes one or more lenses (focusing lenses) that are movable along the optical path of the return light LB, and adjusts the focus of the fundus camera 10 (imaging system 40) under the control of the control device 18. The focusing of the imaging system 40 by the focusing optical system 36 and the focusing of the illumination system 20 by the slit aperture diaphragm 26 are performed in conjunction according to the diopter (visual intensity) of the eye E being examined. The return light LB that enters the focusing optical system 36 from the optical path dividing material 34 enters the imaging system lens 42. Note that instead of providing one or more movable focusing lenses in the focusing optical system 36, one or more variable focus lenses may be provided, and the method of focusing is not particularly limited.

[0028] The imaging lens 42 is composed of one or more lenses and focuses the reflected light LB incident from the focusing optical system 36 onto the image sensor 44.

[0029] The image sensor 44 has a light-receiving surface 44a to which the reflected light LB from the imaging lens 42 is incident. The image sensor 44 also has a rolling shutter function that captures (receives and detects) the reflected light LB while staggering the start and end timing of exposure for each region (including each pixel and each line) within the light-receiving surface 44a. During slit scan imaging, the image sensor 44 is driven by the control device 18 to capture the reflected light LB of the illumination light LS that moves within the fundus Ef in accordance with the deflection of the illumination light LS from the optical scanner 30, and outputs the imaging signal of the reflected light LB to the control device 18.

[0030] [Functions of the Control Device] Figure 2 is a functional block diagram of the control device 18. As shown in Figure 2, the functions of the control device 18 are realized using various processors. These various processors include CPUs (Central Processing Units), GPUs (Graphics Processing Units), ASICs (Application Specific Integrated Circuits), and programmable logic devices [e.g., SPLDs (Simple Programmable Logic Devices), CPLDs (Complex Programmable Logic Devices), and FPGAs (Field Programmable Gate Arrays)]. The various functions of the control device 18 may be realized by a single processor, or by multiple processors of the same or different types.

[0031] The control device 18, by executing a control program (not shown), functions as an illumination control unit 50, a deflection control unit 52, an imaging control unit 54, a signal acquisition unit 56, and an image generation unit 58 during slit scan imaging of the fundus Ef. Note that the "~units" described in relation to the control device 18 may also be "~circuits," "~devices," or "~equipment." In other words, the "~units" described may consist of firmware, software, hardware, or a combination thereof.

[0032] The illumination control unit 50 controls the on / off switching of illumination light LS emitted from the light source 22 (illumination system 20). During slit scan imaging, the illumination control unit 50 emits illumination light LS from the light source 22. This illumination light LS passes through various parts of the illumination system 20 and enters the fundus Ef. As a result, the reflected light LB from the fundus Ef passes through various parts of the imaging system 40 and enters the light-receiving surface 44a of the image sensor 44.

[0033] Figure 3 is an explanatory diagram comparing the fundus Ef (see reference numeral 3A) and the light-receiving surface 44a (see reference numeral 3B) of the image sensor 44 during slit scan imaging. In Figure 3, reference numeral R1A indicates the illumination area R1A (imaging area) of the illumination light LS within the fundus Ef, and reference numeral R1B indicates the incident area R1B (pattern image of the illumination light LS) of the reflected light LB incident on the light-receiving surface 44a. In addition, reference numeral R2B in Figure 3 indicates the light-receiving area R2B (active exposure area) within the light-receiving surface 44a, and reference numeral R2A indicates the corresponding range R2A within the fundus Ef that corresponds to the light-receiving area R2B.

[0034] The individual positional shapes of the illumination area R1A and corresponding area R2A within the fundus Ef, and the individual positional shapes of the incident area R1B and light-receiving area R2B within the light-receiving surface 44a, are not limited to the example shown in Figure 3 and may be changed as appropriate.

[0035] As shown in Figure 3 and Figure 2 described above, the deflection control unit 52 controls the deflection of the illumination light LS by the optical scanner 30. During slit scan imaging, the deflection control unit 52 controls the optical scanner 30 to deflect the illumination light LS at a constant speed (linearly) in the Y direction, for example, by rotating the mirror of the optical scanner 30 at a constant speed. As a result, the inside of the fundus Ef is scanned in the Y direction by the illumination light LS (slit light).

[0036] In accordance with the Y-direction deflection of the illumination light LS, the illumination area R1A of the illumination light LS within the fundus Ef moves in the Y-direction (see reference numeral 3A in Figure 3). Also, in accordance with this movement of the illumination area R1A, the incident area R1B of the reflected light LB within the light-receiving surface 44a moves in the Y-direction (see reference numeral 3B in Figure 3).

[0037] The imaging control unit 54 controls the drive of the image sensor 44. During slit scan imaging, while the illumination light LS by the optical scanner 30 is deflected in the Y direction, that is, while the illumination area R1A in the fundus Ef is moving in the Y direction, the imaging control unit 54 drives (operates) the rolling shutter of the image sensor 44.

[0038] Specifically, the imaging control unit 54, in response to (synchronized with) the movement of the incident region R1B in the Y direction within the light-receiving surface 44a, continuously performs imaging of the reflected light LB using a local light-receiving region R2B (in this case, a rectangular light-receiving region R2B parallel to the X direction) at a position corresponding to the incident region R1B within the light-receiving surface 44a. As a result, the imaging control unit 54 repeatedly performs imaging of the reflected light LB using the light-receiving region R2B while making the light-receiving region R2B follow the incident region R1B moving in the Y direction within the light-receiving surface 44a (see reference numeral 3B).

[0039] Note that the position and shape of the illumination area R1A within the fundus Ef, and the individual position and shape of the incident area R1B and the light-receiving area R2B within the light-receiving surface 44a, are not limited to the example shown in Figure 3 and may be changed as appropriate.

[0040] The signal acquisition unit 56 is connected to the image sensor 44 via a communication interface (not shown) by wire or wireless connection. The signal acquisition unit 56 sequentially acquires imaging signals (also called detection signals or received signals) from the light-receiving area R2B of the image sensor 44 while the illumination light LS is being deflected by the optical scanner 30.

[0041] Figure 4 is an explanatory diagram showing an example of a fundus image D generated by the image generation unit 58. As shown in Figure 4 and Figure 2 described above, the image generation unit 58 generates a fundus image D based on the imaging signal acquired by the signal acquisition unit 56 while the illumination light LS is being deflected by the optical scanner 30. This fundus image D is subjected to various image processing by an image processing unit (not shown), including correction processing to correct distortion caused by distortion aberrations in the illumination system 20 and the imaging system 40. The fundus image D after image processing is then displayed by the display unit 16.

[0042] <Distortion Aberrations in the Illumination and Imaging Systems> Figure 5 is an explanatory diagram illustrating the distortion of the incident region R1B caused by the barrel distortion aberration of the imaging system 40. Figure 6 is an explanatory diagram illustrating the distortion of the incident region R1B caused by the pincushion distortion aberration of the imaging system 40.

[0043] The optical system (such as lenses) of the illumination system 20 has a certain distortion aberration (on-axis aberration), and the optical system (such as lenses) of the imaging system 40 also has a certain distortion aberration (off-axis aberration). Barrel distortion and pincushion distortion are known as such types of distortion. For example, as shown in FIG. 5, when the imaging system 40 has barrel distortion, the incident region R1B of the return light LB is distorted from the ideal state ND into a barrel shape. Further, as shown in FIG. 6, when the imaging system 40 has barrel distortion, the incident region R1B of the return light LB is distorted from the ideal state ND into a pincushion shape.

[0044] FIG. 7 is a graph showing the ratio of the imaging magnification at the periphery of the angle of view to the imaging magnification at the center of the angle of view in the imaging system 40, that is, the difference in image size between the periphery of the angle of view and the center of the angle of view. Note that reference numeral 7A is a graph when the distortion of the imaging system 40 is barrel distortion, and reference numeral 7B is a graph when the distortion of the imaging system 40 is pincushion distortion.

[0045] As shown by reference numeral 7A in FIG. 7, when the distortion of the imaging system 40 is barrel distortion, and the change in the ray angle of the return light LB incident on the optical system from the object side in the imaging system 40 is constant speed (constant angle), the moving speed (displacement speed) in the Y direction of the incident region R1B on the light-receiving surface 44a of the image sensor 44 becomes slower as the distance from the center of the angle of view increases (as the position gets closer to the periphery of the angle of view). Conversely, as shown by reference numeral 7B in FIG. 7, when the distortion of the imaging system 40 is pincushion distortion, and the change in the ray angle of the return light LB incident on the imaging system 40 is constant speed, the moving speed of the incident region R1B becomes faster as the distance from the center of the angle of view increases (as the position gets closer to the periphery of the angle of view).

[0046] FIG. 8 is a graph showing the difference (ratio) of the scanning speed of the illumination light LS at the periphery of the angle of view to the scanning speed of the illumination light LS at the center of the angle of view in the illumination system 20. Note that reference numeral 8A is a graph when the distortion of the illumination system 20 is barrel distortion, and reference numeral 8B is a graph when the distortion of the illumination system 20 is pincushion distortion. As shown in FIG. 8, when the illumination system 20 has pincushion distortion or barrel distortion, the angular displacement of the illumination light LS by the optical scanner 30 (the deflection speed of the illumination light LS) and the displacement of the ray angle on the pupil (the scanning speed of the illumination light LS relative to the fundus Ef) are not linear.

[0047] As indicated by reference numeral 8A in FIG. 8, when the illumination light LS is deflected at a constant speed (linearly) by the optical scanner 30, if the distortion aberration of the illumination system 20 is pincushion distortion between the optical scanner 30 and the pupil of the eye E to be examined, the scanning speed of the illumination light LS decreases as the distance from the center of the angle of view increases (as the periphery of the angle of view is approached), that is, as the ray angle on the pupil increases. Conversely, when the distortion aberration of the illumination system 20 is barrel distortion, if the illumination light LS is deflected at a constant speed by the optical scanner 30, the scanning speed of the illumination light LS increases as the distance from the center of the angle of view increases (as the periphery of the angle of view is approached), that is, as the ray angle on the pupil increases.

[0048] As described above, when the distortion aberrations of the illumination system 20 and the imaging system 40 are both barrel distortion, the closer from the center of the angle of view to the periphery, the slower the scanning speed of the illumination light LS becomes, and the slower the moving speed of the incident region R1B on the light receiving surface 44a becomes. For this reason, as described in Patent Document 1, when both the illumination system 20 and the imaging system 40 are configured to have barrel distortion, the decrease in the scanning speed of the illumination light LS at the periphery of the angle of view caused by the illumination system 20 and the decrease in the moving speed of the incident region R1B at the periphery of the angle of view caused by the imaging system 40 are synergized, resulting in a remarkable decrease in the moving speed of the incident region R1B at the periphery of the angle of view.

[0049] Conversely, when the distortion aberrations of the illumination system 20 and the imaging system 40 are both pincushion distortion, the closer from the center of the angle of view to the periphery, the faster the scanning speed of the illumination light LS becomes, and the faster the moving speed of the incident region R1B on the light receiving surface 44a becomes. For this reason, as described in Patent Document 1, when both the illumination system 20 and the imaging system 40 are configured to have pincushion distortion, the increase in the scanning speed of the illumination light LS at the periphery of the angle of view caused by the illumination system 20 and the increase in the moving speed of the incident region R1B at the periphery of the angle of view caused by the imaging system 40 are synergized, resulting in a remarkable increase in the moving speed of the incident region R1B at the periphery of the angle of view.

[0050] Therefore, as described in Patent Document 1 above, if the distortion aberrations of the illumination system 20 and the imaging system 40 are of the same type (barrel-shaped or pincushion-shaped), even if the illumination light LS is deflected at a constant speed (linearly) by the optical scanner 30, the incident region R1B on the light-receiving surface 44a of the image sensor 44 cannot be moved at a constant speed (linearly), and the incident region R1B moves nonlinearly.

[0051] On the other hand, the movement of the light-receiving area R2B by the rolling shutter drive of the image sensor 44 is performed at a constant speed (linearly). Therefore, in the method described in Patent Document 1, a misalignment occurs between the incident area R1B and the light-receiving area R2B within the light-receiving surface 44a, which may result in insufficient light intensity being secured for the light-receiving area R2B, causing the fundus image D to become dark. Accordingly, in the method described in Patent Document 1, it is necessary to widen the width of the light-receiving area R2B so that the incident area R1B is included within the light-receiving area R2B even if there is a misalignment between the movement speed of the incident area R1B and the movement speed of the light-receiving area R2B. As a result, there was a risk of degradation of the fundus image D due to a decrease in the S / N ratio and the effects of ghosting and flare.

[0052] Figure 9 is an explanatory diagram showing the combination of distortion aberration of the illumination system 20 and distortion aberration of the imaging system 40. As shown in Figure 9, in this embodiment, if the distortion aberration of either the illumination system 20 or the imaging system 40 is "barrel-shaped", the distortion aberration of the other illumination system 20 or imaging system 40 is made "pincushion-shaped", thereby balancing the distortion aberrations of the illumination system 20 and the imaging system 40 and causing the incident region R1B to move at a constant velocity (linear). Here, constant velocity includes approximately constant velocity (approximately linear).

[0053] For example, if the distortion of the illumination system 20 is "barrel-shaped," the distortion of the imaging system 40 is set to "pincushion-shaped." As a result, the scanning speed of the illumination light LS slows down as you move from the center to the periphery of the field of view, but conversely, the movement speed of the incident region R1B on the light-receiving surface 44a increases. Therefore, overall, the incident region R1B can be moved at a constant speed even at the periphery of the field of view.

[0054] Furthermore, if the distortion of the illumination system 20 is "pincushion type," the distortion of the imaging system 40 is set to "barrel type." As a result, the scanning speed of the illumination light LS increases as you move from the center to the periphery of the field of view, but conversely, the movement speed of the incident region R1B on the light-receiving surface 44a decreases. Therefore, even in this case, the incident region R1B can be moved at a constant speed even at the periphery of the field of view when viewed as a whole.

[0055] Therefore, by making the distortion of either the illumination system 20 or the imaging system 40 "barrel-shaped" and the distortion of the other illumination system 20 or imaging system 40 "pincushion-shaped," the incident region R1B can be moved at a constant velocity (linearly). In this case, it is preferable to make the degree of the curves the same (including approximate agreement) across the entire range of the graph shown by reference numeral 7A in Figure 7 and the graph shown by reference numeral 8B in Figure 8, and to make the degree of the curves the same (including approximate agreement), i.e., ±0, across the entire range of the graph shown by reference numeral 7B in Figure 7 and the graph shown by reference numeral 8A in Figure 8. This makes it possible to more reliably move the incident region R1B at a constant velocity even at the edges of the field of view.

[0056] Figure 10 is a comparison of the width W1 (see reference numeral XA) of the light-receiving region R2B in the comparative example (Patent Document 1 above) and the width W1 (see reference numeral XB) of the light-receiving region R2B in this embodiment. In the figure, reference numeral W2 represents the width of the incident region R1B (illumination region R1A). Furthermore, width W1 corresponds to the "width of the light-receiving region in the second direction" in this disclosure, and width W2 corresponds to the "width of the incident region in the second direction" in this disclosure.

[0057] As shown by the symbol XA in Figure 10, in the comparative example, the incident region R1B moves nonlinearly within the light-receiving surface 44a, causing a discrepancy in the movement speeds of the incident region R1B and the light-receiving region R2B. Therefore, it was necessary to widen the width of the light-receiving region R2B so that the incident region R1B would be included within the light-receiving region R2B.

[0058] In contrast, as shown by the symbol XB in Figure 10, in this embodiment, by making the distortion of one of the illumination system 20 and the imaging system 40 "barrel-shaped" and the distortion of the other "pincushion-shaped," the incident region R1B can be moved at a constant velocity (linearly) together with the light-receiving region R2B. As a result, the incident region R1B and the light-receiving region R2B can be moved in almost perfect synchronization on the light-receiving surface 44a, so in this embodiment, the width W1 of the light-receiving region R2B can be made narrower than in the comparative example. For this reason, the width W1 of the light-receiving region R2B in this embodiment is set to satisfy W1 ≥ W2. And, as W1 approaches W2, the decrease in the S / N ratio and the effects of ghosting and flare are reduced, so ideally the width W1 of the light-receiving region R2B is W1 = W2 (including cases where it is slightly larger than W2).

[0059] Furthermore, in order to reduce the decrease in the signal-to-noise ratio and the effects of ghosting and flare, a predetermined upper limit may be set for the width W1 of the light-receiving region R2B [for example, less than K times the width W2 of the incident region R1B (for example, K is any real number satisfying 1 < K < 2)].

[0060] As described above, in this embodiment, by making the distortion of one of the illumination system 20 and the imaging system 40 "barrel-shaped" and the distortion of the other "pincushion-shaped," the incident region R1B can be moved at a constant velocity (linearly) together with the light-receiving region R2B, so that the incident region R1B and the light-receiving region R2B can move synchronously. As a result, the width W1 of the light-receiving region R2B can be narrowed compared to conventional methods, and as a result, the deterioration of the S / N ratio, the effects of ghosting and flare are suppressed, and the deterioration of the fundus image D can be reduced. In addition, since the deflection of the illumination light LS by the optical scanner 30 can be performed at a constant velocity, the control of the optical scanner 30 is simplified.

[0061] [Other] In each of the above embodiments, illumination light LS is irradiated onto the fundus Ef from the fundus camera 10. However, the shape of the illumination light irradiated onto the fundus Ef is not particularly limited and may be changed to any shape such as a spot light, line light, or dot light. In this case, the shape of the light receiving area R2B on the light receiving surface 44a may be appropriately changed to match the shape of the illumination light. Also, when using a spot light or dot light as the illumination light, an optical scanner 30 capable of two-dimensional deflection of the illumination light is used.

[0062] In the embodiments described above, a CMOS-type image sensor 44 having a rolling shutter function was used as an example of the detector of this disclosure, but various known detectors may also be used.

[0063] In the above embodiment, Figure 1 shows an example of the arrangement of the illumination system 20, optical scanner 30, and imaging system 40 of the fundus camera 10, but the arrangement of each of these parts can be changed as appropriate.

[0064] In the above embodiment, the optical scanner 30 deflects the illumination light LS at a constant velocity (linearly), but the deflection of the illumination light LS may be performed nonlinearly so that the incident region R1B moves at a constant velocity.

[0065] In the embodiments described above, a fundus camera 10 for photographing the fundus Ef of the eye under examination was used as an example. However, this disclosure is applicable to various ophthalmic devices for observing (including fluorescence observation) various parts of the eye under examination E, in which the illumination system 20 and the imaging system 40 are separate.

[0066] Some or all of the above embodiments may also be described as follows, but are not limited to the following:

[0067] [Addendum 1] An ophthalmic apparatus comprising: an illumination system that irradiates illumination light onto a part of the area to be observed of the eye to be examined; an optical scanner that deflects the illumination light irradiated from the illumination system onto the area to be observed, thereby moving the illumination area of ​​the illumination light within the area to be observed; and an imaging system that, while the optical scanner is deflecting the illumination light, receives the reflected light from the illumination area that moves within the area to be observed in accordance with the deflection of the illumination light, wherein the distortion aberration of one of the illumination system and the imaging system is barrel-shaped, and the distortion aberration of the other of the illumination system and the imaging system is pincushion-shaped.

[0068] [Addendum 2] The ophthalmic apparatus according to Addendum 1, wherein the optical scanner deflects the illumination light at a constant velocity.

[0069] [Addendum 3] The ophthalmic apparatus according to Addendum 1 or 2, wherein the imaging system comprises a detector having a light-receiving surface into which the reflected light is incident, and the detector repeatedly detects the reflected light in the light-receiving region while the optical scanner is deflecting the illumination light, causing the light-receiving region to track the incident region of the reflected light that moves within the light-receiving surface in accordance with the movement of the illumination region, and the detector displaces the light-receiving region within the light-receiving surface at a constant velocity.

[0070] [Appendix 4] An ophthalmic apparatus according to any one of the appendix items 1 to 3, comprising an objective optical system, wherein the imaging system comprises a detector having a light-receiving surface into which the reflected light is incident, the detector repeatedly detects the reflected light in the light-receiving region while the optical scanner deflects the illumination light, causing the light-receiving region that detects the reflected light within the light-receiving surface to follow the incident region of the reflected light that moves within the light-receiving surface in accordance with the movement of the illumination region, the direction perpendicular to the optical axis of the objective optical system is defined as the first direction, and the direction perpendicular to both the optical axis of the objective optical system and the first direction is defined as the second direction, the illumination system irradiates the area to be observed with slit light parallel to the first direction as the illumination light, the optical scanner deflects the slit light in the second direction, and when the width of the light-receiving region in the second direction is W1 and the width of the incident region in the second direction is W2, W1 ≥ W2.

[0071] [Appendix 5] The ophthalmic apparatus according to Appendix 4, wherein the width of the light-receiving region in the second direction is W1 = W2.

[0072] [Note 6] The ophthalmic apparatus according to any one of Notes 1 to 5, wherein if the distortion of the illumination system is barrel-shaped, the scanning speed of the illumination light with respect to the observed area slows down as you move from the center of the field of view to the periphery; if the distortion of the illumination system is pincushion-shaped, the scanning speed of the illumination light with respect to the observed area speeds up as you move from the center of the field of view to the periphery; if the distortion of the imaging system is barrel-shaped, the peripheral part of the image captured by the imaging system shrinks; and if the distortion of the imaging system is pincushion-shaped, the peripheral part of the image captured by the imaging system stretches.

[0073] 10... Fundus camera 12... Camera head 14... Operation unit 16... Display unit 18... Control device 20... Illumination system 22... Light source 24... Aperture 26... Slit aperture diaphragm 28... Illumination system lens 30... Optical scanner 31... Lens 34... Optical path splitting material 36... Focusing optical system 38... Objective lens 40... Imaging system 42... Imaging system lens 44... Image sensor 44a... Light receiving surface 50... Illumination control unit 52... Deflection control unit 54... Imaging control unit 56... Signal acquisition unit 58... Image generation unit D... Fundus image E... Eye under examination Ea... Anterior segment Ef... Fundus L... Illumination light LB... Reflected light LS... Illumination light ND... Ideal state R1A... Illumination area R1B... Incident area R2A... Corresponding range R2B... Light receiving area

Claims

1. An ophthalmic apparatus comprising: an illumination system that irradiates illumination light onto a part of the area to be observed of the eye under examination; an optical scanner that deflects the illumination light irradiated from the illumination system onto the area to be observed, thereby moving the illumination area of ​​the illumination light within the area to be observed; and an imaging system that, while the optical scanner is deflecting the illumination light, receives the reflected light from the illumination area that moves within the area to be observed in accordance with the deflection of the illumination light, wherein the distortion aberration of one of the illumination system and the imaging system is barrel-shaped, and the distortion aberration of the other of the illumination system and the imaging system is pincushion-shaped.

2. The ophthalmic apparatus according to claim 1, wherein the optical scanner deflects the illumination light at a constant velocity.

3. The ophthalmic apparatus according to claim 2, wherein the imaging system comprises a detector having a light-receiving surface into which the reflected light is incident, and the detector repeatedly detects the reflected light in the light-receiving region while the optical scanner is deflecting the illumination light, causing the light-receiving region to track the incident region of the reflected light that moves within the light-receiving surface in accordance with the movement of the illumination region, and the detector displaces the light-receiving region within the light-receiving surface at a constant velocity.

4. An ophthalmic apparatus according to claim 3, comprising an objective optical system, wherein when the direction perpendicular to the optical axis of the objective optical system is defined as the first direction, and the direction perpendicular to both the optical axis of the objective optical system and the first direction is defined as the second direction, the illumination system irradiates the area to be observed with slit light parallel to the first direction as illumination light, the optical scanner deflects the slit light in the second direction, and when the width of the light-receiving area in the second direction is W1 and the width of the incident area in the second direction is W2, W1 ≥ W2.

5. The ophthalmic apparatus according to claim 4, wherein the width of the light-receiving region in the second direction satisfies W1 = W2.

6. The ophthalmic apparatus according to any one of claims 1 to 5, wherein, if the distortion of the illumination system is barrel-shaped, the scanning speed of the illumination light with respect to the observed area slows down as you move from the center of the field of view to the periphery; if the distortion of the illumination system is pincushion-shaped, the scanning speed of the illumination light with respect to the observed area speeds up as you move from the center of the field of view to the periphery; if the distortion of the imaging system is barrel-shaped, the peripheral part of the image captured by the imaging system shrinks; and if the distortion of the imaging system is pincushion-shaped, the peripheral part of the image captured by the imaging system stretches.

Images