Ophthalmic devices

Abstract

To provide an ophthalmologic apparatus that allows a focusing state of the ophthalmologic apparatus for an observed site to be evaluated at low cost and with a high degree of precision, and to provide a control method of the ophthalmologic apparatus.SOLUTION: An ophthalmologic apparatus includes: an illumination system for emitting illumination light to part of an observed site of an eye to be examined; an optical scanner for deflecting the illumination light emitted to the observed site from the illumination system and moving an illumination region of the illumination light in the observed site; a modulation control part for controlling the illumination system and modulating the intensity of the illumination light once or more than once while the optical scanner is deflecting the illumination light; a light reception system having a detector for detecting return light from the illumination region moving in the observed site according to the deflection of the illumination light while the optical scanner is deflecting the illumination light; and a focusing evaluation part for evaluating a focusing state of the light reception system for the observed site on the basis of a detection signal of the return light detected by the detector.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an ophthalmic apparatus capable of deflecting illumination light that illuminates a part of an observation site of a subject's eye, and a control method thereof. [Background technology]

[0002] There is known a slit-scan type fundus camera (ophthalmic device) for photographing the fundus of a subject eye (see Patent Document 1). The fundus camera described in Patent Document 1 uses an optical scanner to deflect slit light (illumination light) that is irradiated onto the fundus, and captures the return light from the illumination area of ​​the slit light moving within the fundus with a CMOS (Complementary Metal Oxide Semiconductor) type imaging element with a rolling shutter function. This makes it possible to obtain a fundus image with the effects of unnecessary scattered light suppressed.

[0003] With such a fundus camera, before starting to photograph the fundus, it is necessary to evaluate the focus state (also called the focusing situation) of the fundus camera with respect to the fundus, and perform focusing control (focus adjustment) to focus the fundus camera on the fundus based on the evaluation results.

[0004] For example, in the fundus camera described in Patent Document 2, split index light is irradiated onto the fundus, and the return light of the split index light from the fundus is detected by a detector. Based on the detection result, the focus state of the fundus camera is evaluated and focus control is performed.

[0005] In the ophthalmic device (auto reflex keratometer) described in Patent Document 3, a ring illumination light is irradiated onto the fundus, and the return light of the ring illumination light from the fundus is detected by a detector, and based on the detection result, the focus state of the ophthalmic device is evaluated and the focus control is performed. Furthermore, in the ophthalmic device (auto reflex keratometer) described in Patent Document 4, the contrast (contrast difference) of the fundus image is used as an index to evaluate the focus state of the ophthalmic device with respect to the fundus and to perform the focus control. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5735211 [Patent Document 2] Patent No. 6518054 [Patent Document 3] JP 2014-108310 A [Patent Document 4] JP 2016-159071 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the method described in Patent Document 2 or Patent Document 3 is applied to a slit-scan type fundus camera in order to evaluate the focusing state of the fundus camera, it is necessary to provide a separate illumination system that emits split index light or ring illumination light to the fundus camera, which increases costs.

[0008] Furthermore, when the method described in Patent Document 4 is applied to a slit-scan type fundus camera, it is not necessary to provide a separate illumination system, but the following other problem arises.

[0009] Fig. 21 shows a fundus image D (in-focus image) captured by a fundus camera focused on the fundus Ef. Fig. 22 shows a fundus image D (out-of-focus image) captured by a fundus camera not focused on the fundus Ef. Figs. 21 and 22 also show the luminance value for each Y coordinate of the fundus image D along an arbitrary detection line ML parallel to the Y direction.

[0010] 21 and 22, in the fundus image D, the luminance value is low in the portion corresponding to the blood vessels in the fundus Ef, and the luminance value is high in the portion without blood vessels. In the fundus image D, the higher the focus of the fundus camera on the fundus Ef, the larger the luminance value difference ΔV (contrast), which is the difference between the high and low luminance values.

[0011] In this case, a fundus camera generally uses infrared light (near-infrared light), to which the eye has low sensitivity, as illumination light for evaluating the focusing state, so the brightness value difference ΔV is low even for a fundus image D (focused image). Therefore, when comparing a fundus image D (focused image) with a fundus image D (unfocused image), there is no clear difference in the brightness value difference ΔV. As a result, when evaluating the focusing state using the contrast of the fundus image D as an index, there is a risk that the accuracy will decrease or the evaluation will fail.

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ophthalmic apparatus and a control method thereof that are capable of evaluating the focusing state of the ophthalmic apparatus with respect to a site to be observed at low cost and with high accuracy. [Means for solving the problem]

[0013] An ophthalmologic apparatus for achieving the object of the present invention includes an illumination system for irradiating an illumination light onto a part of an observation site of an eye to be examined, an optical scanner for deflecting the illumination light irradiated onto the observation site from the illumination system to move an illumination area of ​​the illumination light within the observation site, a modulation control unit for controlling the illumination system to modulate the intensity of the illumination light one or more times while the optical scanner is deflecting the illumination light, a light receiving system having a detector for detecting return light from the illumination area moving within the observation site in response to the deflection of the illumination light while the optical scanner is deflecting the illumination light, and a focus evaluation unit for evaluating a focusing state of the light receiving system with respect to the observation site based on a detection signal of the return light detected by the detector. The return light here refers to light returning from the illumination area of ​​the observation site or an area nearby it, and includes reflected light of the illumination light, scattered light of the illumination light, fluorescence excited by the illumination light and its scattered light, etc.

[0014] With this ophthalmic device, a high-contrast focus evaluation image of the observed area or a detection signal that serves as the basis for the image can be obtained without requiring any additional configuration, and the focus state of the light receiving system can be evaluated based on the focus evaluation image or the detection signal.

[0015] In an ophthalmologic apparatus according to another aspect of the present invention, an image generating unit is provided that generates a focus evaluation image including a plurality of image regions corresponding to different intensities of illumination light based on a detection signal of return light detected by a detector, and the focus evaluation unit evaluates a focus state based on the focus evaluation image generated by the image generating unit, thereby improving the accuracy of the evaluation of the focus state.

[0016] In the ophthalmologic apparatus according to another aspect of the present invention, the detector has a light receiving surface on which the return light is incident, and in response to the movement of the incident area of ​​the return light in the light receiving surface due to the movement of the illumination area, the detector continuously detects the local return light at a position corresponding to the incident area in the light receiving surface, thereby obtaining a detection signal (image pickup signal) that is the basis of a high-contrast focus evaluation image.

[0017] In the ophthalmologic apparatus according to another aspect of the present invention, the modulation control unit controls the illumination system to modulate the intensity of the illumination light into a rectangular wave, thereby allowing a plurality of regions in the fundus to be used as an index for focus evaluation.

[0018] In the ophthalmologic apparatus according to another aspect of the present invention, the modulation control unit controls the illumination system to modulate the intensity of the illumination light into a sinusoidal shape, thereby allowing a plurality of regions in the fundus to be used as an index for focus evaluation.

[0019] 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 a slit light parallel to the first direction as illumination light onto the observed area, and the optical scanner deflects the slit light in the second direction.

[0020] In an ophthalmologic apparatus according to another aspect of the present invention, an illumination system irradiates a site to be observed with spot light as illumination light, and an optical scanner causes the site to be two-dimensionally scanned with the spot light.

[0021] In another aspect of the ophthalmic device of the present invention, the device includes an image generation unit that generates a focus evaluation image including a plurality of image areas corresponding to different illumination light intensities based on a detection signal of return light detected by the detector, and a repetition control unit that repeatedly executes a detection process including irradiating the observation site with illumination light by the illumination system, deflecting the illumination light by the optical scanner, and detecting the return light by the detector, wherein the modulation control unit alternately switches the modulation pattern of the illumination light intensity in the detection process between a first modulation pattern and a second modulation pattern that is in opposite phase to the first modulation pattern each time the detection process is executed, and the image generation unit alternately generates, as focus evaluation images each time the detection process is executed, a first focus evaluation image based on the detection signal detected by the detector under the first modulation pattern and a second focus evaluation image based on the detection signal detected by the detector under the second modulation pattern.

[0022] In an ophthalmologic apparatus according to another aspect of the present invention, a difference image generating unit is provided that generates a difference image between the first focus evaluation image and the second focus evaluation image, and the focus evaluation unit evaluates the focus state based on the difference image, thereby enabling the focus state to be evaluated based on the difference image with reduced noise, thereby improving the accuracy of the evaluation of the focus state.

[0023] In another aspect of the present invention, an ophthalmologic apparatus includes a special image generating unit that generates a sum image or an average image of a first focus evaluation image and a second focus evaluation image, and a display unit that displays the sum image or the average image, and a focus image evaluating unit evaluates a focus state based on the sum image or the average image, whereby a composite image that is a focus evaluation image of the observed area can be presented to the examiner even during evaluation of the focus state.

[0024] According to another aspect of the present invention, an ophthalmic apparatus includes a focus optical system provided in an optical path of the return light, and a focus control unit that performs focus control of the focus optical system based on an evaluation result of the focus evaluation unit, thereby making it possible to focus the light receiving system on the site to be observed.

[0025] A control method for an ophthalmic apparatus for achieving the object of the present invention includes an illumination system that irradiates illumination light onto a part of an observed area of ​​a subject's eye, and an optical scanner that deflects the illumination light irradiated from the illumination system to the observed area and moves the illumination area of ​​the illumination light within the observed area, the control method including a modulation control step of modulating the intensity of the illumination light at least once while the optical scanner is deflecting the illumination light, a detection step of detecting, with a detector of the light receiving system, return light from the illumination area that moves within the observed area in accordance with the deflection of the illumination light while the optical scanner is deflecting the illumination light, and a focus evaluation step of evaluating the focus state of the light receiving system with respect to the observed area based on a detection signal of the return light detected by the detector in the detection step. Effect of the Invention

[0026] The present invention can evaluate the focusing state of an ophthalmic apparatus with respect to a site to be observed at low cost and with high accuracy. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram of a fundus camera according to a first embodiment. [Diagram 2] FIG. 2 is a functional block diagram of a control device. [Diagram 3] FIG. 3 is an explanatory diagram comparing the fundus (see symbol 3A) and the light receiving surface of the image sensor (see symbol 3B) during slit scan photography. [Figure 4] FIG. 4 is an explanatory diagram showing an example of a fundus image generated by an image generating unit. [Diagram 5] 11 is an explanatory diagram showing an example of illumination intensity modulation of a slit light executed by an illumination control unit during preliminary photography; FIG. [Figure 6] FIG. 11 is an explanatory diagram showing an example of a focus evaluation image generated in the pre-photographing; [Figure 7] 1 is an explanatory diagram of a focus evaluation image (focused image) pre-photographed by a fundus camera in which a light receiving system is focused on the fundus. FIG. [Figure 8] 1 is an explanatory diagram of a focusing evaluation image (out-of-focus image) pre-photographed by a fundus camera whose light receiving system is not focused on the fundus. FIG. [Figure 9] 5 is a flowchart showing a flow of a slit-scan type fundus photographing process by the fundus camera of the first embodiment, in particular, a flow of a process for evaluating the focus state of a light receiving system. [Figure 10] 13 is an explanatory diagram for explaining a modified example of illumination intensity modulation of the slit light during pre-photographing. FIG. [Figure 11] 11 is an explanatory diagram showing an example of a focus evaluation image generated in the modified example shown in FIG. 10; [Figure 12] FIG. 11 is a block diagram of a fundus camera according to a second embodiment. [Figure 13] FIG. 11 is an explanatory diagram showing an example of illumination intensity modulation of a slit light executed by an illumination control unit during preliminary photography in the second embodiment. [Figure 14] 13 is an explanation showing an example of a focus evaluation image captured in pre-photographing under a first modulation pattern and an example of a focus evaluation image captured in pre-photographing under a second modulation pattern. [Figure 15] 11 is an explanatory diagram for explaining generation of a difference image by a difference image generating unit; FIG. [Figure 16] 10 is an explanatory diagram for explaining generation of a composite image by a composite image generating unit; FIG. [Figure 17] 13 is a flowchart showing a flow of a slit-scan type fundus photographing process by a fundus camera according to a second embodiment, in particular, a flow of a process for evaluating the focus state of a light receiving system. [Figure 18] FIG. 11 is an explanatory diagram for explaining a pre-imaging performed by a scanning laser microscope (SLO) according to a third embodiment. [Figure 19] 19 is an explanatory diagram showing an example of a focus evaluation image obtained in the pre-photographing shown in FIG. 18. [Figure 20] 13A and 13B are explanatory diagrams showing examples of other focus evaluation images generated in the pre-photographing; [Figure 21] 1 shows a fundus image (in-focus image) captured by a fundus camera focused on the fundus. [Figure 22] 1 shows a fundus image (out-of-focus image) taken by a fundus camera that is not focused on the fundus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] [First embodiment] <Overall configuration of fundus camera> 1 is a schematic diagram of a fundus camera 10 according to a first embodiment of the present invention. In the diagram, among the mutually orthogonal XYZ directions, the X direction is the left-right direction based on the subject (the interpupillary direction of the subject's eye E), the Y direction is the up-down direction, and the Z direction is the front-rear direction (also called the working distance direction) parallel to the front direction approaching the subject and the rear direction away from the subject.

[0029] 1, a fundus camera 10 corresponds to the ophthalmologic device of the present invention, and photographs the fundus Ef of the subject's eye E by a slit scan method (hereinafter, abbreviated as slit scan photography). This fundus camera 10 is roughly equipped with a camera head 12 (also called the device main body), an operation unit 14, a display unit 16, and a control device 18.

[0030] The camera head 12 is provided with various optical systems and the like required for slit scan photography, which will be described in detail later. Although not shown, the camera head 12 is held so as to be relatively movable in the XYZ directions by a drive mechanism (not shown). This allows the camera head 12 to be relatively movable in the XYZ directions with respect to the subject's eye E, making it possible to align the camera head 12 with the subject's eye E.

[0031] The operation unit 14 accepts inputs for various operations of the fundus camera 10, such as an operation to start slit scan photography, an operation to move the camera head 12 in the XYZ directions, and an operation to set the fundus camera 10.

[0032] Various known displays such as an LCD (Liquid Crystal Display) are used as the display unit 16. The display unit 16 displays a fundus image D, which is an observation image (front image) of the fundus Ef generated by a control device 18 described later, and various setting screens.

[0033] 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 the control device 18. The control device 18 comprehensively controls the operation of each unit of the camera head 12 and the display unit 16 based on an operation instruction input to the operation unit 14. For example, the control device 18 executes various controls and processes including alignment, focus evaluation, and focus control of the camera head 12, slit scan photography by the camera head 12, and generation and display of a fundus image D.

[0034] <Camera head configuration> The camera head 12 includes an illumination system 20, an optical scanner 30, and a light receiving system 40.

[0035] The illumination system 20 irradiates illumination light LS (slit light) onto a part of the fundus Ef via an optical scanner 30 described below. The illumination system 20 includes a light source 22, an aperture 24, a slit aperture 26, an illumination system lens 28, a lens 31, an optical path splitting member 34, and an objective lens 38. The aperture 24, the optical scanner 30, the optical path splitting member 34, and the anterior segment Ea of the subject's eye E are in an optically conjugate relationship.

[0036] The light source 22 emits illumination light L. Visible light is used as this illumination light L during actual photography, which will be described later, and infrared light, which is light in the infrared region (including the near-infrared region) to which the subject's eye E has low sensitivity, is used during pre-photography for checking focus, which will be described later. Visible light may also be used during pre-photography. 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 enters a slit aperture diaphragm 26 via an aperture diaphragm 24.

[0037] 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 the 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). 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 the slit aperture diaphragm 26, the illumination system 20 can be focused on the fundus Ef.

[0038] 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 with each other. The optical path splitting material 34 and the objective lens 38 will be described later.

[0039] A projector capable of emitting illumination light LS may be used as the illumination system 20. Examples of such projectors include an LCD projector, an LCOS (Liquid crystal on silicon) projector using a reflective liquid crystal panel, and a projector 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.

[0040] 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 is capable of reflecting the illumination light LS incident from the illumination system lens 28 toward the lens 31 and deflecting the illumination light LS.

[0041] 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).

[0042] 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 return light LB, which is incident from the objective lens 38 and will be described later, and emits it toward the focus optical system 36. Note that the optical path splitting material 34 can use various splitters as long as it can split the illumination light LS and the return light LB, reflect the illumination light LS toward the objective lens 38, and emit the return light LB toward the focus optical system 36.

[0043] The objective lens 38 irradiates the illumination light LS reflected by the optical path splitting member 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, so that the inside of the fundus Ef is scanned in the Y direction with the illumination light LS (slit light) parallel to the X direction. While the illumination light LS is being deflected in the Y direction, 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 member 34.

[0044] 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 which corresponds to the detector of the present invention.

[0045] The focus optical system 36 includes one or more lenses (focus lenses) movable 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 incident on the focus optical system 36 from the optical path splitter 34 is incident on the light-receiving system lens 42. Instead of providing one or more movably-mounted 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.

[0046] 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 .

[0047] 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 for capturing (receiving, detecting) the return light LB while shifting the timing of the start and end of exposure for each region (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 an image of 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 capturing signal of the return light LB to the control device 18.

[0048] <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.

[0049] 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, a focus evaluation unit 60, a focus control unit 62, and a display control unit 64. Note that what is described as a "unit" of the control device 18 may 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.

[0050] The illumination control unit 50 controls the emission of the illumination light L from the light source 22, i.e., the emission of the illumination light LS from the illumination system 20. In addition, the illumination control unit 50 controls the light source 22 to modulate the illumination intensity of the illumination light LS (illumination light L) while the illumination light LS is being deflected by the optical scanner 30 during slit scan photography (pre-photography) performed to evaluate the focusing state of the light receiving system 40 with respect to the fundus Ef, which will be described in detail later.

[0051] Fig. 3 is an explanatory diagram comparing the fundus Ef (see reference symbol 3A) and the light receiving surface 44a (see reference symbol 3B) of the image sensor 44 during slit scan photography. Reference symbol R1A in Fig. 3 indicates an illumination area R1A of the illumination light LS in the fundus Ef, and reference symbol R1B indicates an incidence area R1B (pattern image of the illumination light LS) of the return light LB incident on the light receiving surface 44a. Reference symbol R2B in Fig. 3 indicates a light receiving area R2B (active exposure area) in the light receiving surface 44a, and reference symbol R2A indicates an imaging range R2A imaged by the light receiving area R2B in the fundus Ef.

[0052] In the figure, the width of the imaging range R2A is larger than the width of the illumination region R1A, and the width of the light-receiving region R2B is larger than the width of the entrance region R1B, but this is not limited to the above. That is, the individual positional shapes of the illumination region R1A and the imaging range R2A in the fundus Ef and the individual positional shapes of the entrance region R1B and the light-receiving region R2B in the light-receiving surface 44a are not limited to the example shown in Fig. 3, and may be changed as appropriate (the same applies to other figures).

[0053] 3 and the above-described FIG. 2, the deflection control unit 52 controls the deflection angle of the illumination light LS by the optical scanner 30. The 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 inside of the fundus Ef in the Y direction with the illumination light LS (slit light).

[0054] In response to the deflection of the illumination light LS in the Y direction, an 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, an incidence area R1B of the return light LB moves in the Y direction in the light receiving surface 44a (see reference symbol 3B in FIG. 3).

[0055] The imaging control unit 54 controls the driving of the imaging element 44. The 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, that is, while the illumination area R1A is moving in the Y direction within the fundus Ef.

[0056] Specifically, the imaging control unit 54 continuously captures images of the return light LB by the local light receiving region R2B at a position corresponding to the incident region R1B on the light receiving surface 44a in response to (synchronization with) the movement of the incident region 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 region R2B while making the light receiving region R2B follow the incident region R1B moving in the Y direction on the light receiving surface 44a (see reference symbol 3B).

[0057] In other words, within the fundus Ef, while the local imaging range R2A is made to follow the illumination area R1A moving in the Y direction, the imaging element 44 continuously captures the imaging range R2A (see reference symbol 3A). Since such rolling shutter driving is a known technique, a detailed description thereof will be omitted (see Patent Document 1 above).

[0058] The signal acquiring unit 56 is connected by wire or wirelessly to the image sensor 44 via a communication interface (not shown). The signal acquiring 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.

[0059] Fig. 4 is an explanatory diagram showing an example of a fundus image D generated by the image generating unit 58. As shown in Fig. 4 and the above-described Fig. 2, the image generating unit 58 generates a fundus image D based on an imaging signal acquired by the signal acquiring unit 56 while the optical scanner 30 is deflecting the illumination light LS.

[0060] 2, the focus evaluation unit 60 evaluates the focus state of the light receiving system 40 (including the focus optical system 36) with respect to the fundus Ef, and the focus control unit 62 performs focus control of the focus optical system 36. The display control unit 64 controls the display of the fundus image D and various setting screens, etc., on the display unit 16, as will be described in detail later.

[0061] <Evaluation of focus state> Next, evaluation of the focusing state of the light receiving system 40 on the fundus Ef (hereinafter simply referred to as "evaluation of the focusing state") will be described. In this embodiment, in order to evaluate the focusing state without providing an additional component to the camera head 12 having a slit scan photography function, the focusing state is evaluated using the contrast of the image of the fundus Ef as an index. In this case, since the fundus camera 10 uses illumination light LS in the infrared wavelength range for evaluating the focusing state, there is a risk that the contrast of the image of the fundus Ef will decrease, resulting in a decrease in the accuracy of the evaluation of the focusing state.

[0062] Therefore, in this embodiment, the illumination control unit 50 modulates the illumination intensity of the illumination light LS during slit scan photographing of the fundus Ef to generate a focus evaluation image DS (see FIG. 6) that is a high-contrast image for focus evaluation, and the focus state is evaluated based on this focus evaluation image DS. Hereinafter, the slit scan photographing performed to evaluate the focus state will be referred to as "pre-photographing", and the slit scan photographing performed after focus control of the focus optical system 36 will be referred to as "main photographing".

[0063] 5 is an explanatory diagram showing an example of the illumination intensity modulation of the illumination light LS executed by the illumination control unit 50 during the preliminary photography. Note that the illumination control unit 50 functions as a modulation control unit of the present invention during the preliminary photography.

[0064] As shown in Fig. 5 and Fig. 2, during the deflection of the illumination light LS in the Y direction during pre-photographing, i.e., during the movement of the illumination area R1A in the Y direction, the illumination control unit 50 controls the light source 22 to modulate the illumination intensity of the illumination light L into a substantially rectangular wave shape, thereby periodically repeating the strong and weak illumination intensity. As a result, during the deflection of the illumination light LS, a state in which the illumination intensity of the illumination light LS is "strong" as shown by reference numeral 5A in Fig. 5 and a state in which the illumination intensity is "weak" as shown by reference numeral 5B are periodically repeated. As a result, during the deflection of the illumination light LS during pre-photographing, imaging of the imaging range R2A irradiated with the illumination light LS having a strong illumination intensity and imaging of the imaging range R2A irradiated with the illumination light LS having a weak illumination intensity (including substantially zero) are alternately performed.

[0065] Fig. 6 is an explanatory diagram showing an example of a focus evaluation image DS generated in the pre-photographing. As shown in Fig. 6, the image generating unit 58 generates the focus evaluation image DS based on the imaging signal acquired by the signal acquiring unit 56 while the pre-photographing is being performed.

[0066] The focus evaluation image DS includes multiple types (roughly two types) of image regions corresponding to different illumination intensities of the illumination light LS. Specifically, in the focus evaluation image DS, bright regions 65a corresponding to the image of the imaging range R2A illuminated with the illumination light LS having a high illumination intensity and dark regions 65b corresponding to the image of the imaging range R2A illuminated with the illumination light LS having a low illumination intensity are alternately formed in the Y direction. As a result, in the focus evaluation image DS, the dark regions 65b parallel to the X direction are formed in stripes at equal intervals along the Y direction, forming a light and dark pattern.

[0067] Fig. 7 is an explanatory diagram of a focusing evaluation image DS (focused image) pre-photographed by the fundus camera 10 in a state where the light receiving system 40 is focused on the fundus Ef. Fig. 8 is an explanatory diagram of a focusing evaluation image DS (unfocused image) pre-photographed by the fundus camera 10 in a state where the light receiving system 40 is not focused on the fundus Ef. Figs. 8 and 9 show the luminance value for each Y coordinate of the focusing evaluation image DS along an arbitrary detection line ML parallel to the Y direction.

[0068] 7 and 8, when the focus evaluation image DS (focused image) is compared with the focus evaluation image DS (unfocused image), a clear difference occurs in the brightness value difference ΔV (contrast), which indicates the contrast difference of the light and dark patterns. Therefore, by using the contrast of the light and dark patterns of the focus evaluation image DS as an index, it is possible to evaluate the focus state.

[0069] Returning to FIG. 2, the focus evaluation unit 60 evaluates the focus state based on the focus evaluation image DS generated by the image generation unit 58. For example, the focus evaluation unit 60 evaluates the focus state based on the amplitude of the first component of the signal obtained by Fourier transforming the signal of the focus evaluation image DS. In this embodiment, a light and dark pattern is formed in a stripe shape in the focus evaluation image DS, so that the focus state can be evaluated in multiple regions (multiple locations) in the focus evaluation image DS. This allows multiple regions in the fundus Ef, not just a portion of the fundus Ef, to be used as an index for focus evaluation.

[0070] In addition, instead of evaluating the focus state based on the focus evaluation image DS, the focus evaluation unit 60 may evaluate the focus state using a known method based on the imaging signal acquired by the signal acquisition unit 56 while the pre-shooting is being performed, i.e., the imaging signal output from the imaging element 44.

[0071] Based on the evaluation result of the focus state by the focus evaluation unit 60, when the light receiving system 40 is not focused on the fundus Ef, the focus control unit 62 performs focus control of the focus optical system 36 to focus the light receiving system 40 on the fundus Ef.

[0072] The method of controlling the focus of the focus optical system 36 by the focus control unit 62 is not particularly limited, and a known method may be used. For example, the focus state may be evaluated for each of a plurality of lens positions of the focus lens of the focus optical system 36, and the focus lens may be moved to the lens position that provides the highest evaluation.

[0073] <Function of the Fundus Camera 10 of the First Embodiment> FIG. 9 is a flow chart showing the flow of fundus photographing processing of the slit scan type by the fundus camera 10 of the first embodiment configured as described above, in particular, the flow of the processing for evaluating the focusing state of the light receiving system 40, which corresponds to the control method of the ophthalmic apparatus of the present invention.

[0074] 9, after the subject's face is supported by a face support unit (not shown), the examiner operates the operation unit 14 to start shooting, and then the alignment of the camera head 12 with the subject's eye E is performed by a known method (step S1). The illumination control unit 50 starts emitting illumination light L (infrared light) from the light source 22, so that the illumination light LS is irradiated from the illumination system 20 to the fundus Ef. Then, after the alignment is completed, pre-photography is started (step S2).

[0075] When the pre-photography is started, as shown in Fig. 5, the deflection control unit 52 controls the optical scanner 30 to deflect the illumination light LS in the Y direction, and the illumination control unit 50 controls the light source 22 to periodically repeat the intensity modulation of the illumination light LS irradiated to the fundus Ef (steps S3 and S4). Note that step S4 corresponds to the modulation control step of the present invention.

[0076] At the same time, the imaging control unit 54 drives the imaging element 44 with a rolling shutter in accordance with the deflection of the illumination light LS by the optical scanner 30, and starts imaging the return light LB by the light receiving area R2B while making the light receiving area R2B follow the incident area R1B moving in the Y direction within the light receiving surface 44a (step S5). Note that step S5 corresponds to the detection step of the present invention.

[0077] Thereafter, the processes of steps S4 and S5 are repeatedly executed until the deflection of the illumination light LS is completed (NO in step S6). As a result, while the illumination light LS is deflected in the Y direction, imaging of the imaging range R2A irradiated with the illumination light LS having a high illumination intensity and imaging of the imaging range R2A irradiated with the illumination light LS having a low illumination intensity are alternately executed along the Y direction within the fundus Ef. As a result, it is possible to generate a focus evaluation image DS with high contrast.

[0078] Moreover, while the illumination light LS is being deflected in the Y direction, the signal acquiring unit 56 successively acquires imaging signals from the light receiving region R2B of the imaging element 44.

[0079] When the deflection of the illumination light LS is completed (YES in step S6), the image generation unit 58 generates the focus evaluation image DS shown in FIG. 6 described above based on the imaging signal acquired by the signal acquisition unit 56 from the imaging element 44 while the deflection of the illumination light LS is being performed (step S7).

[0080] Next, the focus evaluation unit 60 evaluates the focus state based on the focus evaluation image DS generated by the image generation unit 58, for example, using a Fourier transform method (step S8, which corresponds to the focus evaluation step of the present invention). This allows multiple regions in the fundus Ef to be used as an index for focus evaluation. The focus evaluation unit 60 may also evaluate the focus state based on the imaging signal output from the imaging element 44 during pre-photography.

[0081] Then, the focusing control unit 62 performs focusing control of the focus optical system 36 using a known method based on the evaluation result of the focusing state by the focusing evaluation unit 60, thereby focusing the light receiving system 40 on the fundus Ef (step S9).

[0082] When the focusing control by the focusing control unit 62 is completed, the illumination control unit 50, the imaging control unit 54, the signal acquisition unit 56, and the image generation unit 58 of the control device 18 are operated to perform actual photography of the fundus oculi Ef (step S10). The fundus image D photographed in this actual photography is displayed on the display unit 16 by the display control unit 64.

[0083] <Advantages of the First Embodiment> As described above, in the fundus camera 10 of the first embodiment, a high-contrast focus evaluation image DS or an image signal on which the focus evaluation image DS is based is obtained by performing pre-photography and modulating the illumination intensity of the illumination light LS during the pre-photography. This improves the accuracy of the evaluation of the focus state based on the focus evaluation image DS or the image signal. Furthermore, the pre-photography and the modulation of the illumination intensity of the illumination light LS during the pre-photography can be achieved simply by changing the control program of the fundus camera 10, and no additional configuration is required. As a result, the evaluation of the focus state of the light receiving system 40 with respect to the fundus Ef can be performed at low cost and with high accuracy.

[0084] <Modification of illumination intensity modulation of slit light> Fig. 10 is an explanatory diagram for explaining a modified example of the illumination intensity modulation of the illumination light LS during pre-photographing. Fig. 11 is an explanatory diagram showing an example of a focus evaluation image DS1 generated in the modified example shown in Fig. 10.

[0085] In the first embodiment described above, while the illumination light LS is deflected in the Y direction during pre-photographing, the illumination intensity of the illumination light LS is modulated into an approximately rectangular wave shape. However, the illumination intensity of the illumination light LS may also be modulated into a sine wave shape, for example, as shown in FIG. 10.

[0086] Even when the illumination intensity of the illumination light LS is modulated sinusoidally in this manner, imaging of the imaging range R2A illuminated with the illumination light LS having a high illumination intensity and imaging of the imaging range R2A illuminated with the illumination light LS having a low illumination intensity are repeatedly performed while the illumination light LS is being deflected in the Y direction. As a result, a focus evaluation image DS1 is generated by the image generating unit 58, as shown in FIG.

[0087] The focus evaluation image DS1 includes a plurality of image regions corresponding to different illumination intensities of the illumination light LS. These image regions include light and dark patterns (light regions 65a and dark regions 65b) formed in stripes in the focus evaluation image DS1. Therefore, similar to the first embodiment, it is possible to evaluate the focus state using the contrast of the focus evaluation image DS1 as an index.

[0088] [Second embodiment] Fig. 12 is a block diagram of the fundus camera 10 of the second embodiment. The fundus camera 10 of the second embodiment repeatedly executes pre-photographing and alternately switches the modulation pattern of the illumination intensity of the illumination light LS between a first modulation pattern and a second modulation pattern for each pre-photographing to generate a difference image DF (see Fig. 15) and a sum image DM (see Fig. 16).

[0089] 12, the fundus camera 10 of the second embodiment has basically the same configuration as the first embodiment, except that the control device 18 functions as a repetitive control unit 66 and the functions of the illumination control unit 50, the image generation unit 58, the focus evaluation unit 60, and the display control unit 64 are partially different from those of the first embodiment. Therefore, the same reference numerals are used for the same functions or configurations as those of the first embodiment, and the description thereof will be omitted.

[0090] When the focusing state of the light receiving system 40 is evaluated, the repetitive control unit 66 controls the illumination control unit 50, the deflection control unit 52, the imaging control unit 54, and the signal acquisition unit 56 to repeatedly execute pre-photographing (corresponding to the detection process of the present invention).

[0091] Fig. 13 is an explanatory diagram showing an example of illumination intensity modulation of illumination light LS executed by the illumination control unit 50 during pre-photography in the second embodiment. As shown in Fig. 13 and the already-described Fig. 12, the illumination control unit 50 in the second embodiment alternately switches the modulation pattern of the illumination intensity of illumination light LS during pre-photography between a first modulation pattern shown by reference symbol XIIIA in Fig. 13 and a second modulation pattern shown by reference symbol XIIIB in Fig. 13 every time pre-photography is repeated.

[0092] The first modulation pattern is the same pattern as that of the first embodiment shown in Fig. 5. The second modulation pattern is a pattern of opposite phase to the first modulation pattern. Note that the first modulation pattern may be the sine wave pattern shown in Fig. 10, and in this case, the second modulation pattern is a cosine wave pattern.

[0093] Figure 14 is an explanation showing an example of a focus evaluation image DS2 (see symbol XIVA) captured in pre-shooting under the first modulation pattern, and a focus evaluation image DS3 (see symbol XIVB) captured in pre-shooting under the second modulation pattern.

[0094] As shown by reference symbol XIVA in Fig. 14, when pre-photographing under the first modulation pattern is performed, the image generating unit 58 in the second embodiment generates a focus evaluation image DS2 (corresponding to the first focus evaluation image of the present invention) based on the imaging signal acquired by the signal acquiring unit 56 during this pre-photographing. Also, as shown by reference symbol XIVB in Fig. 14, when pre-photographing under the second modulation pattern is performed, the image generating unit 58 generates a focus evaluation image DS3 (corresponding to the second focus evaluation image of the present invention) based on the imaging signal acquired by the signal acquiring unit 56 during this pre-photographing.

[0095] The focus evaluation image DS2 is the same image as the focus evaluation image DS of the first embodiment (see FIG. 6), and includes the same light and dark pattern (light areas 65a and dark areas 65b alternately formed in the Y direction) as in the first embodiment. On the other hand, the focus evaluation image DS3 has a light and dark pattern (dark areas 65b and light areas 65a alternately formed in the Y direction) in which the light areas 65a and dark areas 65b of the focus evaluation image DS2 are interchanged.

[0096] Moreover, the image generating section 58 in the second embodiment functions as a difference image generating section 58a and a sum image generating section 58b.

[0097] Fig. 15 is an explanatory diagram for explaining generation of the difference image DF by the difference image generating unit 58a, and Fig. 16 is an explanatory diagram for explaining generation of the sum image DM by the sum image generating unit 58b.

[0098] As shown in Fig. 15 and Fig. 12, the difference image generation unit 58a generates a difference image DF by subtracting the focus evaluation image DS3 from the focus evaluation image DS2 every time the focus evaluation image DS2 and the focus evaluation image DS3 are generated by the image generation unit 58. By subtracting the focus evaluation image DS3 from the focus evaluation image DS2, noise components contained in both images are cancelled, and a difference image DF with reduced noise is generated. Then, the difference image generation unit 58a outputs this difference image DF to the focus evaluation unit 60 every time it generates a difference image DF.

[0099] As shown in Fig. 16 and the above-described Fig. 12, the sum image generation unit 58b corresponds to the special image generation unit of the present invention, and generates a sum image DM of the focus evaluation image DS2 and the focus evaluation image DS3 every time the image generation unit 58 generates a focus evaluation image DS2 and a focus evaluation image DS3. In this way, a sum image DM similar to the fundus image D is generated. Then, the sum image generation unit 58b outputs this sum image DM to the display control unit 64 every time it generates the sum image DM.

[0100] The focus evaluation unit 60 of the second embodiment evaluates the focus state based on the difference image DF input from the difference image generation unit 58a. The specific evaluation method is the same as the focus state evaluation method based on the focus evaluation image DS of the first embodiment, so a detailed description will be omitted.

[0101] The display control unit 64 of the second embodiment displays the sum image DM input from the sum image generation unit 58b on the display unit 16. This makes it possible to present the sum image DM, which is a focus evaluation image of the fundus Ef, to the examiner. Note that instead of providing the sum image generation unit 58b that generates the sum image DM, an average image generation unit that generates an average image of the focus evaluation image DS2 and the focus evaluation image DS3 may be provided, and this average image may be displayed on the display unit 16.

[0102] FIG. 17 is a flowchart showing the flow of fundus photographing processing of the slit scan type by the fundus camera 10 of the second embodiment, in particular the flow of processing for evaluating the focusing state of the light receiving system 40.

[0103] As shown in Fig. 17, when alignment is completed (step S11) in the same manner as in the first embodiment, the illumination control unit 50 sets the modulation pattern of the illumination intensity of the illumination light LS to the first modulation pattern (step S12). Then, as shown by reference symbol XIIIA in Fig. 13, the pre-photographing described in steps S3 to S6 (see Fig. 9) in the first embodiment is performed under the first modulation pattern (step S13), and then the image generating unit 58 generates a focus evaluation image DS2 as shown by reference symbol XIVA in Fig. 14 (step S14).

[0104] Next, the illumination control unit 50 sets the modulation pattern of the illumination intensity of the illumination light LS to the second modulation pattern (step S15). Then, under the control of the repetitive control unit 66, pre-photographing is performed under the second modulation pattern as shown by reference symbol XIIIB in Fig. 13 (step S16), and then the image generating unit 58 generates a focus evaluation image DS3 as shown by reference symbol XIVA in Fig. 14 (step S17).

[0105] When the focus evaluation images DS2 and DS3 are generated, the difference image generating unit 58a generates the difference image DF shown in FIG. 15 based on the focus evaluation images DS2 and DS3, and the sum image generating unit 58b generates the sum image DM shown in FIG. 16 (step S18). Then, the difference image generating unit 58a outputs the difference image DF to the focus evaluation unit 60, and the sum image generating unit 58b outputs the sum image DM to the display control unit 64. As a result, the display control unit 64 displays the sum image DM on the display unit 16, allowing the examiner to observe the fundus Ef even during the evaluation of the focus state. As described above, an average image of the focus evaluation images DS2 and DS3 may be generated instead of the sum image DM and displayed on the display unit 16.

[0106] Next, the focus evaluation unit 60 evaluates the focus state based on the difference image DF input from the difference image generation unit 58a in the same manner as in the first embodiment (step S19). At this time, the focus state is evaluated based on the difference image DF in which noise has been reduced, so that the accuracy of the evaluation of the focus state can be improved compared to the first embodiment.

[0107] Then, the focusing control unit 62 performs focusing control of the focus optical system 36 based on the evaluation result of the focusing state by the focusing evaluation unit 60 in the same manner as in the first embodiment, thereby focusing the light receiving system 40 on the fundus Ef (step S20). At this time, in the second embodiment, the accuracy of the evaluation of the focusing state is improved compared to the first embodiment, so that the accuracy of the focusing control can be improved compared to the first embodiment.

[0108] Thereafter, until the actual shooting begins, the processes from step S12 to step S20, i.e., pre-shooting under the first modulation pattern, generation of a focus evaluation image DS2, pre-shooting under the second modulation pattern, generation of a focus evaluation image DS3, generation of a difference image DF and a sum image DM, evaluation of the focus state, and focus control, are repeatedly executed (step S21).

[0109] Then, with the light receiving system 40 focused on the fundus Ef, the illumination control unit 50, the imaging control unit 54, the signal acquisition unit 56, and the image generation unit 58 of the control device 18 are operated to perform actual photography of the fundus Ef (step S22).

[0110] As described above, in the second embodiment, while repeatedly executing pre-photographing, the modulation pattern of the illumination intensity of the illumination light LS during pre-photographing is alternately switched between the first modulation pattern and the second modulation pattern for each pre-photographing, thereby generating a difference image DF and a sum image DM from the focus evaluation images DS2 and DS3. As a result, it is possible to improve the accuracy of the evaluation of the focus state and the focus control based on the difference image DF. In addition, the sum image DM can be presented to the examiner from the display unit 16 even during the evaluation of the focus state.

[0111] [Third embodiment] In each of the above embodiments, the fundus camera 10 having a slit scan photographing function has been described as an example, but the present invention can also be applied to various ophthalmic devices capable of deflecting various illumination lights that illuminate a part of the subject's eye E, such as a scanning laser ophthalmoscope (hereinafter, abbreviated as SLO). The SLO deflects the illumination light LP (see FIG. 18) irradiated to the fundus Ef in a two-dimensional direction (for example, the XY direction) by the optical scanner 30, and detects the return light LB of the illumination light LP from the fundus Ef with a detector (photomultiplier tube, avalanche photodiode). Note that the specific configuration of the SLO is a publicly known technology, so a detailed description will be omitted here (see JP 2020-142119 A).

[0112] Fig. 18 is an explanatory diagram for explaining the pre-photographing performed by the SLO according to the third embodiment of the present invention, and Fig. 19 is an explanatory diagram showing an example of a focus evaluation image DS4 obtained by the pre-photographing shown in Fig. 18.

[0113] 18, the SLO of the third embodiment performs pre-photography of the fundus Ef in the same manner as the fundus camera 10 of each of the above-mentioned embodiments. The pre-photography of the third embodiment includes two-dimensional deflection (two-dimensional scanning) of spot-shaped illumination light LP (spot light) that is irradiated onto the fundus Ef, and detection of return light LB from the illumination area of ​​the fundus Ef irradiated with the illumination light LP. When performing two-dimensional deflection of the illumination light LP, in this embodiment, high-speed deflection SC1 (high-speed scanning) is performed in the X direction, and low-speed deflection SC2 (low-speed scanning) is performed in the Y direction.

[0114] Then, while performing two-dimensional deflection of the illumination light LP, the SLO periodically modulates the illumination intensity of the illumination light LP (for example, for each scan line in the X direction) in the same manner as in each of the above embodiments. As a result, while performing two-dimensional deflection of the illumination light LP, imaging of an area irradiated with illumination light LP of high illumination intensity and imaging of an area irradiated with illumination light LP of low illumination intensity are periodically and alternately performed.

[0115] 19, while the pre-photographing is being performed, the SLO generates a focus evaluation image DS4 by detecting return light LB of the illumination light LP from the fundus Ef. This focus evaluation image DS4 includes a light-dark pattern in which light areas 65a and dark areas 65b are formed in stripes, similar to the focus evaluation image DS of the first embodiment.

[0116] When the illumination light LP is two-dimensionally deflected, depending on the conditions (e.g., the speeds of the high-speed deflection SC1 and the low-speed deflection SC2), the bright and dark patterns (bright areas 65a and dark areas 65b) may be inclined with respect to the X direction as shown in Fig. 19. Even in this case, there is no particular effect on the evaluation of the focusing state.

[0117] As described above, in the SLO, a high-contrast focus evaluation image DS4 or an image signal on which the image is based can be obtained by performing pre-photography and modulating the illumination intensity of the illumination light LP during the pre-photography. This makes it possible to perform evaluation of the focus state of the SLO on the fundus Ef at low cost and with high accuracy, as in the above-described embodiments.

[0118] [others] Fig. 20 is an explanatory diagram showing an example of another focus evaluation image DS7 generated by pre-photographing in each of the above-mentioned embodiments. In the above-mentioned first embodiment, the dark area 65b is formed in a stripe shape in the focus evaluation image DS, but this dark area 65b may be formed in at least one place in the focus evaluation image DS. Therefore, the illumination intensity of the illumination light LS (including the illumination light LP) may be modulated (turned off or reduced) at least once during pre-photographing to generate a focus evaluation image DS7 as shown in Fig. 20.

[0119] Here, when not only a portion of the fundus Ef but multiple regions within the fundus Ef are used as an index for focus evaluation, it is preferable to modulate the illumination intensity of the illumination light LS so that dark regions 65b are formed at multiple locations within the focus evaluation image DS, as described in each of the above embodiments. Also, in the second and third embodiments, the focus evaluation image DS7 may be generated.

[0120] In the above embodiments, the CMOS type image sensor 44 having a rolling shutter function has been taken as an example of the detector of the present invention, but various known detectors may also be used.

[0121] In each of the above embodiments, illumination light LS or illumination light LP is irradiated onto the fundus Ef from the fundus camera 10 (including SLO), but the shape of the various illumination lights irradiated onto the fundus Ef is not particularly limited and may be changed to any shape, such as line light or dot light.

[0122] 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 these components can be changed as appropriate.

[0123] In each of the above embodiments, a fundus camera 10 (including an SLO) that photographs the fundus Ef of the subject's eye E has been used as an example, but the present invention can be applied to various ophthalmic devices that observe other observed areas of the subject's eye E (e.g., the anterior part Ea) and that are capable of deflecting various illumination lights (including excitation light) that are irradiated to a part of the observed area. [Explanation of symbols]

[0124] 10 Fundus Camera 12 Camera Head 14 Control section 16 Display 18 Control device 20 Lighting System 22 Light source 24 Iris Diaphragm 26 Slit Aperture Diaphragm 28 Lighting Lenses 30 Optical Scanner 31 Lens 34 Optical path splitting material 36 Focus Optical System 38 Objective Lens 40 Light receiving system 42 Light receiving lens 44 Image sensor 44a Photosensitive surface 50 Lighting control unit 52 Deflection control section 54 Imaging control section 56 Signal Acquisition Unit 58 Image Generation Unit 58a Difference image generating unit 58b Japanese image generation section 60 Focus evaluation unit 62 Focus control section 64 Display control section 65a Bright area 65b dark region 66 Repeat control section D fundus image DF difference image DM composite image DS, DS1-DS4, DS7 Focus evaluation images Eye examination Anterior eye segment Fundus Infrared light Return light Illumination light Illumination light Detection line Illumination area Incident area Imaging range Light receiving area High-speed deflection Low-speed deflection Luminance value difference

Claims

1. An illumination system for irradiating a part of an observation area 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 modulation control unit that controls the illumination system to modulate the intensity of the illumination light one or more times while the optical scanner is deflecting the illumination light; a light receiving system having a detector for detecting return light from the illumination area that moves within the observation site in response to the deflection of the illumination light while the optical scanner is deflecting the illumination light; a focusing evaluation unit that evaluates a focusing state of the light receiving system with respect to the object to be observed based on a detection signal of the return light detected by the detector; an image generating unit that generates a focus evaluation image of the observation site including a plurality of image regions corresponding to different intensities of the illumination light based on a detection signal of the return light detected by the detector; a repetition control unit that repeatedly executes a detection process including irradiation of the illumination light by the illumination system onto the observation site, deflection of the illumination light by the optical scanner, and detection of the return light by the detector; Equipped with the modulation control unit alternately switches a modulation pattern of the intensity of the illumination light in the detection process between a first modulation pattern and a second modulation pattern having an opposite phase to the first modulation pattern every time the detection process is executed; an ophthalmic device in which the image generation unit alternately generates, as the focus evaluation image each time the detection process is executed, a first focus evaluation image based on the detection signal detected by the detector under the first modulation pattern and a second focus evaluation image based on the detection signal detected by the detector under the second modulation pattern.

2. an image generating unit that generates a focus evaluation image of the observed region including a plurality of image regions corresponding to different intensities of the illumination light based on a detection signal of the return light detected by the detector, The ophthalmologic apparatus according to claim 1 , wherein the focus evaluation unit evaluates the focus state based on the focus evaluation image generated by the image generation unit.

3. The ophthalmic device of claim 1, wherein the detector has a light receiving surface on which the returning light is incident, and continuously detects localized returning light at a position corresponding to the incident area within the light receiving surface in response to movement of the incident area of ​​the returning light within the light receiving surface due to movement of the illumination area.

4. The ophthalmic apparatus according to claim 1 , wherein the modulation control unit controls the illumination system to modulate the intensity of the illumination light into a rectangular wave.

5. The ophthalmic apparatus according to claim 1 , wherein the modulation control unit controls the illumination system to modulate the intensity of the illumination light into a sinusoidal shape.

6. 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.

7. the illumination system irradiates the observation site with spot light as the illumination light, The ophthalmologic apparatus according to claim 1 , wherein the optical scanner two-dimensionally scans the spot light over the region to be observed.

8. a difference image generating unit that generates a difference image between the first focus evaluation image and the second focus evaluation image, The ophthalmologic apparatus according to claim 1 , wherein the focus evaluation unit evaluates the focus state based on the difference image.

9. a special image generating unit that generates a sum image or an average image of the first focus evaluation image and the second focus evaluation image; a display unit for displaying the sum image or the average image; The ophthalmic apparatus according to claim 1 , further comprising:

10. a focusing optical system provided in an optical path of the return light; a focusing control unit that performs focusing control of the focus optical system based on an evaluation result of the focusing evaluation unit; The ophthalmic apparatus according to claim 1 , further comprising:

Images