JP7565851B2 - Ophthalmic Equipment - Google Patents

Description

The present invention relates to an ophthalmic device equipped with an optical system for illumination and an optical system for receiving light.

A slit-scan fundus camera (ophthalmic device) that photographs the fundus of a subject eye is known (see Patent Document 1). The fundus camera described in Patent Document 1 irradiates the fundus with slit light (illumination light) from an illumination system, while deflecting the slit light irradiated onto the fundus using an optical scanner. At the same time as this deflection, the fundus camera also guides the return light from the illumination area of the slit light moving within the fundus to a light receiving system, and causes this return light to be incident on the light receiving surface of an image sensor arranged in the light receiving system. The image sensor is a CMOS (Complementary Metal Oxide Semiconductor) type with a rolling shutter function, and continuously captures the return light in the light receiving area while making the local light receiving area follow the incident area of the return light that moves within the light receiving surface as the illumination area moves. This allows a fundus image (observation image) to be obtained with reduced effects of unnecessary scattered light.

Patent No. 5735211

Figure 11 is an explanatory diagram for explaining the problem with the slit-scan type fundus camera described in Patent Document 1. In Figure 11, the incidence area R1B of the returning light that is incident on the light receiving surface 44a of the image sensor 44 moves in the Y direction in response to the deflection in the Y direction of the slit light parallel to the X direction, and the light receiving area R2B of the image sensor 44 follows this incidence area R1B.

In order to obtain a good fundus image with the fundus camera described in Patent Document 1, it is necessary to take into consideration the distortion aberration of the illumination system and the light receiving system. Here, for example, in a scanning laser ophthalmoscope (SLO), most of the illumination system and the light receiving system are common (see JP 2020-142119 A), and the illumination light and the return light pass through a common optical system. Therefore, in an SLO, the effects of the distortion aberration of the illumination system and the light receiving system are almost canceled out.

However, in the slit-scan fundus camera described in Patent Document 1, the proportion of the common optical system in the illumination system and the light-receiving system is lower than in an SLO, so the distortion aberration of the illumination system and the light-receiving system is not canceled out as in an SLO. In this case, distortion occurs in the entrance area R1B (pattern image of the slit light) on the light-receiving surface 44a, which may cause the entrance area R1B and the light-receiving area R2B to not coincide with each other, i.e., the entrance area R1B may not be contained within the light-receiving area R2B.

If the incident region R1B is not included within the light receiving region R2B, a sufficient amount of illumination light will not be secured on the light receiving region R2B. For this reason, as shown in FIG. 11, it is necessary to greatly increase the Y-direction width WA of the light receiving region R2B to make the incident region R1B and the light receiving region R2B coincident with each other, that is, to include the incident region R1B within the light receiving region R2B. However, in this case, the fundus image will be degraded due to a deterioration in the signal-to-noise ratio (S/N) of the fundus image and an increase in the effects of ghosts and flares.

One solution to this problem would be to reduce distortion in both the illumination system and the light-receiving system as much as possible, but in this case it would be necessary to increase the number of lenses in the illumination system and the light-receiving system and to improve the machining and assembly precision of the lenses. This would result in increased costs.

The present invention has been made in consideration of these circumstances, and aims to provide an ophthalmic device that can reduce degradation of the observation image of the observed area at low cost.

The ophthalmic apparatus for achieving the object of the present invention comprises an illumination system which irradiates illumination light onto a part of an observed area of a subject's eye, an optical scanner which deflects the illumination light irradiated onto the observed area from the illumination system to move the illumination area of the illumination light within the observed area, and a light receiving system which receives return light from the illumination area which moves within the observed area in response to the deflection of the illumination light while the optical scanner is deflecting the illumination light, and the distortion aberration of both the illumination system and the light receiving system is of the same type. Note that the return light referred to here is light which returns from the illumination area of the observed area or an area nearby, and includes reflected light of the illumination light, scattered light of the illumination light, and fluorescence excited by the illumination light and its scattered light.

This ophthalmic device can reduce the overall distortion of the illumination system and the light receiving system, so that the distortion of the returning light caused by the distortion of the illumination system can be reduced by the light receiving system.

In an ophthalmic device according to another aspect of the present invention, the difference between the two distortion aberrations is equal to or less than a predetermined threshold value. This makes it possible to further reduce the distortion of the returned light.

In another aspect of the present invention, in an ophthalmic device, both distortions are barrel-shaped or pincushion-shaped.

In an ophthalmic device according to another aspect of the present invention, when directions perpendicular to the optical axis of the illumination system and perpendicular to each other are defined as a first direction and a second direction, the illumination system irradiates the observed area with a slit light parallel to the first direction as illumination light, and the optical scanner deflects the slit light in the second direction.

In another aspect of the ophthalmic device of the present invention, the light receiving system is a detector having a light receiving surface on which the returning light is incident, and the detector is a local light receiving area that detects the returning light within the light receiving surface, and is a rectangular light receiving area that is parallel to the first direction, and the detector continuously detects the returning light in the light receiving area while tracking the incident area of the slit light that moves within the light receiving surface in response to the movement of the illumination area, and the width of the light receiving area in the second direction is wider than the width of the incident area in the second direction. This makes it possible to include the incident area within the light receiving area, thereby ensuring a sufficient amount of illumination light on the light receiving area.

An ophthalmic device according to another aspect of the present invention includes an image generating unit that generates an observation image of the observed area based on a light receiving signal of the return light received by the light receiving system.

The present invention can reduce degradation of the observed image of the observed area at low cost.

1 is a schematic diagram of a fundus camera corresponding to an ophthalmic apparatus of the present invention. FIG. 2 is a functional block diagram of a control device. 3A is an explanatory diagram comparing the fundus (see symbol 3A) and the light receiving surface of the imaging element (see symbol 3B) during slit scan photography. FIG. FIG. 4 is an explanatory diagram showing an example of a fundus image generated by an image generating unit. FIG. 1 is an explanatory diagram for explaining barrel distortion (negative distortion). FIG. 1 is an explanatory diagram for explaining pincushion distortion (positive distortion). 1A and 1B are explanatory diagrams for explaining distortion of an illumination area or an entrance area caused by barrel distortion aberration; 1A and 1B are explanatory diagrams for explaining distortion of an illumination area or an entrance area caused by pincushion distortion aberration; 1 is an explanatory diagram showing a combination of distortion aberration in an illumination system and distortion aberration in a light receiving system; FIG. 4 is an explanatory diagram for explaining the width of a light receiving region. 1 is an explanatory diagram for explaining a problem with the slit-scan type fundus camera described in Patent Document 1. FIG.

[Overall configuration of fundus camera]
1 is a schematic diagram of a fundus camera 10 corresponding to an ophthalmologic apparatus of the present invention. In the mutually orthogonal XYZ directions in the figure, the X direction is a left-right direction based on the subject (the interpupillary direction of the subject's eye E), the Y direction is a top-bottom direction, and the Z direction is a front-back direction (also called a working distance direction) parallel to the front direction approaching the subject and the rear direction away from the subject.

As shown in FIG. 1, the fundus camera 10 photographs the fundus Ef of the subject's eye E using a slit scan method (hereinafter, abbreviated as slit scan photography). This fundus camera 10 is roughly divided into a camera head 12 (also called the device body), an operation unit 14, a display unit 16, and a control device 18.

The camera head 12 is provided with various optical systems required for slit scan photography, which will be described in detail later. In addition, although not shown, the camera head 12 is held so as to be movable relative to the subject's eye E in the XYZ directions by a drive mechanism (not shown). This allows the camera head 12 to move relative to the subject's eye E in the XYZ directions, making it possible to align the camera head 12 with the subject's eye E.

The operation unit 14 accepts inputs for various operations of the fundus camera 10, such as starting slit scan photography, moving the camera head 12 in the XYZ directions, and setting the fundus camera 10.

The display unit 16 may be any of a variety of known displays, such as an LCD (Liquid Crystal Display). The display unit 16 displays a fundus image D, which is an observation image (frontal image) of the fundus Ef generated by the control device 18 (described below), as well as various setting screens, etc.

The control device 18 is an arithmetic processing device such as a computer that executes various arithmetic processing and control processing. The camera head 12, the operation unit 14, and the display unit 16 are connected to this control device 18. The control device 18 controls the operation of each part of the camera head 12 and the display unit 16 based on the operation instructions input to the operation unit 14. For example, the control device 18 executes various controls and processes including alignment of the camera head 12, slit scan photography by the camera head 12, and generation and display of a fundus image D.

[Camera head configuration]
The camera head 12 includes an illumination system 20 , an optical scanner 30 , and a light receiving system 40 .

The illumination system 20 irradiates a portion of the fundus Ef with illumination light LS (slit light) via an optical scanner 30 described below. This illumination system 20 includes 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 of the subject's eye E are in an optically conjugate relationship.

The light source 22 emits illumination light L. Visible light is used as this illumination light L, but infrared light, which is light in the infrared region (including the near-infrared region) to which the subject's eye E has low sensitivity, may also be used. The light source 22 may be, but is not limited to, a laser light source, an LED (Light Emitting Diode) light source, a white LED light source, or a laser-excited white light source. The illumination light L emitted from the light source 22 passes through the diaphragm 24 and enters the slit aperture diaphragm 26.

The slit aperture diaphragm 26 generates illumination light LS parallel to the X direction (corresponding to the first direction of the present invention) from the illumination light L incident from the diaphragm 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. Note that the illumination light LS (slit light) is not particularly limited as long as it is perpendicular to the optical axis of the objective lens 38 (illumination system 20). In addition, the slit aperture diaphragm 26 is provided so as to be freely movable along the optical path of the illumination light LS by an actuator (not shown). By moving this slit aperture diaphragm 26, the illumination system 20 can be focused on the fundus Ef.

The illumination system lens 28 is composed of one or more lenses, and emits the illumination light LS incident from the slit aperture diaphragm 26 toward the optical scanner 30. The lens 31 emits the illumination light LS reflected by the optical scanner 30 toward the optical path splitting material 34. The lens 31 makes the optical scanner 30 and the optical path splitting material 34 optically conjugate. The optical path splitting material 34 and the objective lens 38 will be described later.

The illumination system 20 may be a projector capable of emitting illumination light LS. Examples of such projectors include LCD projectors, LCOS (Liquid crystal on silicon) projectors using a reflective liquid crystal panel, and projectors using a DMD (Digital Mirror Device). In this case, the optical scanner 30 may be replaced by a fixed mirror, and the optical scanning performed by the optical scanner 30 may be simulated by changing the pattern of the projector.

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

The polarization direction and deflection angle of the illumination light LS by the optical scanner 30 are controlled by the control device 18. During slit scan photography, 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 of the present invention).

The optical path splitting material 34 reflects the illumination light LS incident from the lens 31 and emits it toward the objective lens 38, and also passes the return light LB incident from the objective lens 38, which will be described later, and emits it toward the focus optical system 36. Note that various splitters can be used as the optical path splitting material 34 as long as it is capable of splitting the illumination light LS and the return light LB, reflecting the illumination light LS toward the objective lens 38, and emitting the return light LB toward the focus optical system 36.

The objective lens 38 irradiates the illumination light LS reflected by the optical path splitting material 34 onto a part of the fundus Ef through the anterior segment Ea (pupil) of the subject's eye E. At this time, the illumination light LS is deflected in the Y direction by the optical scanner 30 described above, and the fundus Ef is scanned in the Y direction with the illumination light LS (slit light) parallel to the X direction. Then, while the illumination light LS is being deflected in the Y direction, the return light LB from the fundus Ef of the subject's eye E irradiated with the illumination light LS enters the focus optical system 36 through the objective lens 38 and the optical path splitting material 34.

The light receiving system 40 includes an objective lens 38, an optical path splitter 34, a focusing optical system 36, a light receiving system lens 42, and a CMOS type image sensor 44.

The focus optical system 36 includes one or more lenses (focus lenses) that can move along the optical path of the return light LB, and adjusts the focus of the fundus camera 10 (light-receiving system 40) under the control of the control device 18. The focusing of the light-receiving system 40 by the focus optical system 36 and the focusing of the illumination system 20 by the slit aperture diaphragm 26 move in conjunction with each other according to the diopter (visual acuity) of the subject's eye E. The return light LB that enters the focus optical system 36 from the optical path splitter 34 enters the light-receiving system lens 42. Note that instead of providing one or more movable focus lenses in the focus optical system 36, one or more variable focus lenses may be provided, and the method of focus adjustment is not particularly limited.

The light receiving lens 42 is composed of one or more lenses, and focuses the return light LB incident from the focus optical system 36 onto the image sensor 44.

The image sensor 44 has a light receiving surface 44a on which the return light LB from the light receiving lens 42 is incident, and has a rolling shutter function that captures (receives, detects) the return light LB while shifting the timing of the start and end of exposure for each area (including each pixel and each line) within this light receiving surface 44a. During slit scan photography, this image sensor 44 is driven by the control device 18 as a rolling shutter to capture the return light LB of the illumination light LS that moves within the fundus Ef in response to the deflection of the illumination light LS by the optical scanner 30, and outputs an image signal of the return light LB to the control device 18.

[Control device functions]
Fig. 2 is a functional block diagram of the control device 18. As shown in Fig. 2, the functions of the control device 18 are realized by using various processors. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., simple programmable logic devices (SPLD), complex programmable logic devices (CPLD), and field programmable gate arrays (FPGA)). The various functions of the control device 18 may be realized by one processor, or may be realized by multiple processors of the same type or different types.

The control device 18 executes a control program (not shown) to function as an illumination control unit 50, a deflection control unit 52, an imaging control unit 54, a signal acquisition unit 56, an image generation unit 58, an image processing unit 59, and a display control unit 64. Note that what is described as a "unit" of the control device 18 may also be a "circuit", a "device", or a "equipment". In other words, what is described as a "unit" may be composed of firmware, software, hardware, or a combination of these.

The lighting control unit 50 controls the emission of illumination light L from the light source 22, i.e., the emission of illumination light LS from the lighting system 20.

Figure 3 is an explanatory diagram comparing the fundus Ef (see symbol 3A) and the light receiving surface 44a (see symbol 3B) of the image sensor 44 during slit scan photography. Symbol R1A in Figure 3 indicates the illumination area R1A of the illumination light LS in the fundus Ef, and symbol R1B indicates the incidence area R1B (pattern image of the illumination light LS) of the return light LB that enters the light receiving surface 44a. Also, symbol R2B in Figure 3 indicates the light receiving area R2B (active exposure area) in the light receiving surface 44a, and symbol R2A indicates the imaging range R2A imaged by the light receiving area R2B in the fundus Ef.

In the figure, the width of the imaging range R2A is larger than the width of the illumination area R1A, and the width of the light receiving area R2B is larger than the width of the entrance area R1B, but this is not limited to the above. In other words, the individual positional shapes of the illumination area R1A and imaging range R2A within the fundus Ef, and the individual positional shapes of the entrance area R1B and light receiving area R2B within the light receiving surface 44a are not limited to the example shown in FIG. 3, and may be changed as appropriate.

As shown in FIG. 3 and the above-mentioned FIG. 2, the deflection control unit 52 controls the deflection angle of the illumination light LS by the optical scanner 30. This deflection control unit 52 controls the optical scanner 30 during slit scan photography to deflect the illumination light LS in the Y direction, thereby scanning the fundus Ef in the Y direction with the illumination light LS (slit light).

In response to the deflection of the illumination light LS in the Y direction, the illumination area R1A of the illumination light LS in the fundus Ef moves in the Y direction (see reference symbol 3A in FIG. 3). In response to the movement of the illumination area R1A, the incidence area R1B of the return light LB moves in the Y direction within the light receiving surface 44a (see reference symbol 3B in FIG. 3).

The imaging control unit 54 controls the driving of the imaging element 44. This imaging control unit 54 performs rolling shutter driving (operation) of the imaging element 44 while the illumination light LS is deflected in the Y direction by the optical scanner 30 during slit scan photography, i.e., while the illumination area R1A moves in the Y direction within the fundus Ef.

Specifically, the imaging control unit 54 continuously captures images of the return light LB by a local light receiving area R2B (here, a rectangular light receiving area R2B parallel to the X direction) at a position corresponding to the entrance area R1B on the light receiving surface 44a in response to (synchronization with) the movement of the entrance area R1B in the Y direction on the light receiving surface 44a. As a result, the imaging control unit 54 continuously captures images of the return light LB by the light receiving area R2B while making the light receiving area R2B follow the entrance area R1B moving in the Y direction on the light receiving surface 44a (see symbol 3B).

In other words, within the fundus Ef, the imaging element 44 continuously captures an image of the local imaging range R2A while tracking the illumination area R1A moving in the Y direction (see symbol 3A). This type of rolling shutter drive is a known technique, so a detailed description will be omitted (see Patent Document 1 above).

Note that the individual positional shapes of the illumination area R1A and the imaging range R2A within the fundus Ef, and the individual positional shapes of the entrance area R1B and the light receiving area R2B within the light receiving surface 44a are not limited to the example shown in FIG. 3, and may be changed as appropriate.

The signal acquisition unit 56 is connected to the image sensor 44 by wire or wirelessly via a communication interface (not shown). The signal acquisition unit 56 sequentially acquires an image signal (also called a detection signal or a light receiving signal) from the light receiving region R2B of the image sensor 44 while the optical scanner 30 is deflecting the illumination light LS.

Figure 4 is an explanatory diagram showing an example of a fundus image D generated by the image generating unit 58. As shown in Figure 4 and the above-mentioned Figure 2, the image generating unit 58 generates the fundus image D based on the imaging signal acquired by the signal acquiring unit 56 while the illumination light LS is being deflected by the optical scanner 30.

Returning to FIG. 2, the image processing unit 59 performs various image processing on the fundus image D generated by the image generating unit 58, including a correction process for correcting distortion of the fundus image D caused by the distortion aberration of the illumination system 20 and the light receiving system 40. The display control unit 64 causes the display unit 16 to display the fundus image D after image processing by the image processing unit 59, or causes the display unit 16 to display various setting screens of the fundus camera 10, etc.

<Distortion in the illumination system and the light receiving system>
Fig. 5 is a diagram for explaining barrel distortion (negative distortion). Fig. 6 is a diagram for explaining pincushion distortion (positive distortion). Fig. 7 is a diagram for explaining distortion of the illumination region R1A or the entrance region R1B caused by the barrel distortion shown in Fig. 5. Fig. 8 is a diagram for explaining distortion of the illumination region R1A or the entrance region R1B caused by the pincushion distortion shown in Fig. 6.

As shown in Figures 5 to 8 and in Figure 1, the optical systems (lenses, etc.) of the illumination system 20 and the light receiving system 40 have a certain amount of distortion. Examples of such distortion include a barrel type as shown in Figure 5 and a pincushion type as shown in Figure 6.

For example, as shown in FIG. 7, when the illumination system 20 has barrel-shaped distortion, the illumination region R1A of the illumination light LS is distorted from the ideal state ND to a barrel shape, and when the light receiving system 40 has barrel-shaped distortion, the incidence region R1B of the return light LB is distorted from the ideal state ND to a barrel shape. Also, as shown in FIG. 8, when the illumination system 20 has pincushion distortion, the illumination region R1A is distorted from the ideal state ND to a pincushion shape, and when the light receiving system 40 has pincushion distortion, the incidence region R1B is distorted from the ideal state ND to a pincushion shape.

If the illumination system 20 has distortion in this way, when the illumination light LS is deflected at a constant speed (linearly deflected) by the optical scanner 30, the illumination area R1A on the fundus Ef moves nonlinearly and not at a constant speed (linearly). Also, if the light receiving system 40 has distortion, the incident area R1B (pattern image of the illumination light LS) on the light receiving surface 44a will be distorted due to distortion of the return light LB.

Furthermore, due to distortion of the return light LB, the entrance area R1B and the light receiving area R2B do not coincide on the light receiving surface 44a, and there is a risk that a sufficient amount of light will not be secured for the light receiving area R2B. Here, as already shown in FIG. 11, if the width WA of the light receiving area R2B is greatly increased, the fundus image D will deteriorate due to a decrease in the S/N ratio and the effects of ghost flare, so it is necessary to correct the distortion of the return light LB. Furthermore, if an attempt is made to reduce the individual distortion aberrations of the illumination system 20 and the light receiving system 40, it will be necessary to increase the number of lenses and improve the processing accuracy of the lenses, which will increase costs.

In this embodiment, the distortion of the illumination system 20 and the distortion of the light receiving system 40 are of the same type (characteristics), so that the distortion of the return light LB caused by the distortion of the illumination system 20 is reduced by the light receiving system 40. In other words, instead of reducing the distortion of the illumination system 20 and the light receiving system 40 individually, the distortion of the illumination system 20 and the light receiving system 40 as a whole is reduced.

Figure 9 is an explanatory diagram showing a combination of distortion aberration of the illumination system 20 and the light receiving system 40. Note that in Figure 9, "barrel type" and "pincushion type" are given as examples of types of distortion aberration.

9, in this embodiment, when the distortion aberration of the illumination system 20 is "barrel-shaped", the distortion aberration of the light receiving system 40 is "barrel-shaped", and when the distortion aberration of the illumination system 20 is "pincushion-shaped", the distortion aberration of the light receiving system 40 is "pincushion-shaped", thereby reducing the distortion of the return light LB (incident region R1B). In this case, it is only necessary to match the types of distortion aberration of the illumination system 20 and the light receiving system 40, so the design of the illumination system 20 and the light receiving system 40 is simplified compared to the case where the distortion aberration of the illumination system 20 and the light receiving system 40 are reduced individually.

At this time, it is preferable that the difference between the distortion aberration of the illumination system 20 and the distortion aberration of the light receiving system 40 is equal to or less than a predetermined threshold (e.g., 4% or less). This allows the distortion of the return light LB (incident region R1B) to be further reduced. Note that the fundus camera 10 focuses (aligns the focus) on the fundus Ef, and the aberration characteristics of the illumination system 20 and the light receiving system 40 change depending on the ocular refractive power (Diopter) of the subject eye E. In this embodiment, the distortion aberration of both optical systems is approximately matched within the range in which the fundus camera 10 can focus, i.e., the above-mentioned difference is set to or less than a threshold.

In this manner, in this embodiment, by making the types of distortion aberration of the illumination system 20 and the light receiving system 40 the same, it is possible to reduce the distortion of the return light LB (incident region R1B), but it is difficult to completely eliminate the distortion of the return light LB. For this reason, in this embodiment, the Y-direction width WA of the light receiving region R2B is slightly widened so that the incident region R1B is included within the light receiving region R2B on the light receiving surface 44a.

Figure 10 is an explanatory diagram for explaining the width WA of the light receiving region R2B in this embodiment. Note that in Figure 10, the entrance region R1B is illustrated as a distortion-free slit shape to avoid complicating the drawing, but distortion does occur in this entrance region R1B.

As shown in FIG. 10, in this embodiment, the distortion of the return light LB (incident region R1B) is reduced, so unlike the conventional example shown in FIG. 11, it is possible to include the incident region R1B within the light receiving region R2B without significantly increasing the Y-directional width WA of the light receiving region R2B. For example, in this embodiment, by making the width WA of the light receiving region R2B twice (equivalent to 2 degrees) the Y-directional width WS of the incident region R1B (equivalent to 1 degree), the incident region R1B is included within the light receiving region R2B even if there is a deviation of 0.5 degrees between the incident region R1B and the light receiving region R2B. This ensures a sufficient amount of illumination light on the light receiving region R2B while suppressing deterioration of the S/N ratio and the effects of ghosts and flares.

In this embodiment, since it is difficult to completely eliminate distortion of the return light LB (incident region R1B), a certain amount of distortion also occurs in the fundus image D generated by the image generating unit 58, but this distortion can be easily corrected by correction processing by the image processing unit 59.

[Effects of this embodiment]
As described above, in this embodiment, even if the illumination system 20 and the light receiving system 40 are separate, the distortion of the return light LB caused by the distortion of the illumination system 20 can be reduced by the light receiving system 40 by making the distortion of the illumination system 20 the same type as in the conventional case. As a result, the entrance region R1B can be included in the light receiving region R2B without significantly widening the width WA of the light receiving region R2B (see FIG. 11), increasing the number of lenses in the illumination system 20 and the light receiving system 40, using lenses that require high processing accuracy, or improving assembly accuracy. This makes it possible to reduce deterioration of the fundus image D at low cost.

[others]
In each of the above embodiments, the fundus camera 10 irradiates the illumination light LS onto the fundus Ef, but the shape of the illumination light irradiated onto the fundus Ef is not particularly limited and may be changed to any shape, such as spot light, line light, or dot light. In this case, the shape of the light receiving region R2B on the light receiving surface 44a may be appropriately changed to match the shape of the illumination light. In addition, when spot light or dot light is used as the illumination light, an optical scanner 30 capable of two-dimensionally deflecting the illumination light is used.

In each of the above embodiments, a CMOS-type image sensor 44 having a rolling shutter function has been described as an example of a detector of the present invention, but various known detectors may also be used.

In the above embodiment, an example of the arrangement of the illumination system 20, the optical scanner 30, and the light receiving system 40 of the fundus camera 10 is shown in FIG. 1, but the arrangement of each of these parts can be changed as appropriate.

In each of the above embodiments, a fundus camera 10 that photographs the fundus Ef of the subject's eye E has been described as an example, but the present invention can be applied to various ophthalmic devices that observe other observed parts of the subject's eye E (e.g., the anterior segment Ea) and in which the illumination system 20 and the light receiving system 40 are separate.

10 Fundus camera 12 Camera head 14 Operation unit 16 Display unit 18 Control device 20 Illumination system 22 Light source 24 Iris diaphragm 26 Slit aperture diaphragm 28 Illumination system lens 30 Optical scanner 31 Lens 34 Optical path splitting material 36 Focus optical system 38 Objective lens 40 Light receiving system 42 Light receiving 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 59 Image processing unit 64 Display control unit D Fundus image E Eye to be examined Ea Anterior eye portion Ef Fundus L Infrared light LB Return light LS Illumination light ND Ideal state R1A Illumination area R1B Incident area R2A Imaging range R2B Light receiving area

Claims (6)

an illumination system for irradiating a part of an observation site of a subject's eye with illumination light;
an optical scanner that deflects the illumination light irradiated from the illumination system onto the observation site to move an illumination area of the illumination light within the observation site;
a light receiving system that receives return light from the illumination area that moves within the subject area in response to the deflection of the illumination light while the optical scanner is deflecting the illumination light;
Equipped with
An ophthalmic apparatus in which the distortion aberration of both the illumination system and the light receiving system is the same type. The ophthalmic device according to claim 1, wherein the difference between the two distortion aberrations is equal to or less than a predetermined threshold value. The ophthalmic device according to claim 1 or 2, wherein both of the distortions are barrel-shaped or pincushion-shaped. When directions perpendicular to an optical axis of the illumination system and perpendicular to each other are defined as a first direction and a second direction, the illumination system irradiates the observation site with a slit light parallel to the first direction as the illumination light,
The ophthalmic apparatus according to claim 1 , wherein the optical scanner deflects the slit light in the second direction. the light receiving system includes a detector having a light receiving surface on which the return light is incident, the detector being a local light receiving area that detects the return light within the light receiving surface, the light receiving area being a rectangular light receiving area parallel to the first direction, the light receiving area being tracked by the incident area of the slit light that moves within the light receiving surface in response to the movement of the illumination area, and the detector continuously detects the return light in the light receiving area,
The ophthalmic apparatus according to claim 4 , wherein the width of the light receiving area in the second direction is greater than the width of the incident area in the second direction. The ophthalmic device according to any one of claims 1 to 5, further comprising an image generating unit that generates an observation image of the observed area based on a light receiving signal of the return light received by the light receiving system.

Images