JP2022157208A - Ophthalmologic apparatus and control method thereof - Google Patents

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 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 confirmation control part for executing focusing confirmation control for causing the detector to detect return light from the illumination region in a state that the illumination region is fixed in the observed site by controlling the optical scanner.SELECTED DRAWING: Figure 7

Description

The present invention relates to an ophthalmologic apparatus capable of deflecting illumination light that illuminates a portion of an observed region of an eye to be examined, and a control method thereof.

2. Description of the Related Art A slit scan type fundus camera (ophthalmologic apparatus) for photographing the fundus of an eye to be examined is known (see Patent Document 1). The fundus camera described in Patent Document 1 uses an optical scanner to deflect the slit light (illumination light) that irradiates the fundus, and uses a rolling shutter function to detect the return light from the illumination region of the slit light that moves within the fundus. An image is captured by a CMOS (Complementary Metal Oxide Semiconductor) image sensor. As a result, a fundus image in which the influence of scattered light is suppressed can be obtained.

In such a fundus camera, the focus state of the fundus camera with respect to the fundus is evaluated (also referred to as the focus state) before starting to photograph the fundus, and the fundus camera is adjusted to focus on the fundus based on the evaluation result. It is necessary to perform focus control (focus adjustment).

For example, in the fundus camera described in Patent Document 2, the fundus is irradiated with split index light, 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.

In the ophthalmologic apparatus (autoreflection keratometer) described in Patent Document 3, the ocular fundus is irradiated with ring illumination light, and the return light of the ring illumination light from the ocular fundus is detected by a detector. Evaluation of focus state and focus control are performed. Further, in the ophthalmologic apparatus (autoreflection keratometer) described in Patent Document 4, the contrast of the fundus image is used as an index to evaluate the focus state of the ophthalmologic apparatus with respect to the fundus and to perform focus control.

Japanese Patent No. 5735211 Japanese Patent No. 6518054 JP 2014-108310 A JP 2016-159071 A

By the way, when applying the method described in Patent Document 2 or Patent Document 3 to a slit scan type fundus camera in order to evaluate the focused state of the fundus camera, split index light or ring light is applied to the fundus camera. It is necessary to separately provide an illumination system for emitting illumination light, which increases the cost.

Further, when applying the method described in Patent Document 4 to a slit-scanning fundus camera, there is no need to separately provide an illumination system. However, since the retinal camera generally uses infrared light (near-infrared light) with low eye sensitivity as illumination light for evaluating the focus state, the contrast of the fundus image for evaluating the focus state is low. end up As a result, when the focus state is evaluated using the contrast of the fundus image as an index, there is a risk that the accuracy will be degraded or the evaluation will fail.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ophthalmologic apparatus capable of evaluating the focusing state of the ophthalmologic apparatus with respect to a site to be observed at low cost and with high precision, and a control method thereof. .

An ophthalmologic apparatus for achieving the object of the present invention comprises an illumination system that irradiates a portion of an observed region of an eye to be inspected with illumination light, and an illumination system that deflects the illumination light emitted from the illumination system onto the observed region to An optical scanner that moves the illumination area of the illumination light within the observation site, and while the optical scanner is deflecting the illumination light, detects return light from the illumination area that moves within the site to be observed according to the deflection of the illumination light. and a light-receiving system having a detector that controls the optical scanner to fix the illumination area within the site to be observed, and perform focus confirmation control that causes the detector to detect the return light from the illumination area. and a control unit. The term "return light" as used herein refers to light returning from the illuminated area of the site to be observed or from an area in the vicinity thereof. and so on.

In an ophthalmologic apparatus according to another aspect of the present invention, a focus optical system provided in the optical path of the return light, and focus control of the focus optical system based on a detection signal of the return light detected by the detector in focus confirmation control. and a focus control unit that performs

An ophthalmologic apparatus according to another aspect of the present invention includes an image generation unit that generates a focus evaluation image that indicates the focus state of the illumination system and the light receiving system for the site to be observed based on the detection signal, and the focus control unit includes: , focus control is performed based on the focus evaluation image generated by the image generator.

In the ophthalmologic apparatus according to another aspect of the present invention, the focus optical system has a focus lens, and the repeat control unit repeatedly operates the focus confirmation control unit and the image generation unit for each of a plurality of different lens positions of the focus lens. A focus control unit performs focus control based on the focus evaluation image for each lens position generated by the image generation unit.

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 receives light with respect to the return-light incident area that moves within the light-receiving surface in accordance with the movement of the illumination area. A first operation mode in which the return light is continuously detected in the light receiving area while following the local light receiving area for detecting the return light in the plane, and a moving path along which the light receiving area is predetermined in the light receiving plane. and a second operation mode in which the return light from the illumination area fixed by the optical scanner in the focus confirmation control enters the middle of the moving path of the light receiving area, and the focus confirmation control unit drives the detector in the second mode of operation.

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 receives light with respect to the return-light incident area that moves within the light-receiving surface in accordance with the movement of the illumination area. A first operation mode in which return light is continuously detected in the light receiving area while following a local light receiving area for detecting return light in the plane, and a light scanner detects return light from a fixed illumination area. and a third operation mode in which the light receiving area is fixed at a detectable position within the light receiving surface, and the focus confirmation control section drives the detector in the third operation mode.

In the ophthalmologic apparatus according to another aspect of the present invention, when directions perpendicular to the optical axis of the illumination system and mutually orthogonal are defined as the first direction and the second direction, the illumination system provides illumination light parallel to the first direction. The site to be observed is irradiated with slit light, and the optical scanner deflects the slit light in the second direction.

In the ophthalmologic apparatus according to another aspect of the present invention, a plurality of diaphragms are provided in the illumination system, are optically conjugate with the anterior segment of the subject's eye, and are decentered with respect to the illumination optical axis of the illumination system. an aperture provided with an aperture of .

A control method for an ophthalmologic apparatus for achieving the object of the present invention comprises an illumination system that irradiates a portion of an observed region of an eye to be inspected with illumination light, and deflects the illumination light that is emitted from the illumination system to the observed region. an optical scanner for moving the illumination region of the illumination light within the site to be observed; a light-receiving system having a detector for detecting light, and a light-receiving system for detecting light, in a state in which an optical scanner is controlled to fix an illumination region within a site to be observed, return light from the illumination region is directed to the detector. It has an in-focus confirmation control step for detection.

INDUSTRIAL APPLICABILITY The present invention can evaluate the focus state of an ophthalmologic apparatus with respect to a site to be observed at low cost and with high accuracy.

1 is a schematic diagram of a fundus camera; FIG. It is a functional block diagram of a control device. FIG. 3 is an explanatory diagram comparing the fundus (see reference numeral 3A) and the light receiving surface of the imaging device (see reference numeral 3B) during slit scan imaging. FIG. 4 is an explanatory diagram showing an example of a fundus image generated by an image generator; FIG. 5 is an explanatory diagram showing a ray diagram of a luminous flux incident on an eye to be inspected during focusing (see symbol 5A) and a front view of a luminous flux incident on the anterior segment of the eye (see symbol 5B). Reference numerals 6A and 6B are explanatory diagrams showing ray diagrams of light beams incident on the subject's eye when out of focus. FIG. 10 is an explanatory diagram comparing the fundus (see reference numeral 7A) and the light receiving surface of the imaging element (see reference numeral 7B) when focus confirmation control is executed at the time of focusing; FIG. 10 is an explanatory diagram comparing the fundus (see symbol 8A) and the light-receiving surface of the imaging device (see symbol 8B) when focus confirmation control is executed when out of focus; FIG. 4 is an explanatory diagram showing an example of a focus evaluation image generated by an image generation unit during focusing; FIG. 5 is an explanatory diagram showing an example of a focus evaluation image generated by an image generation unit when out of focus; 10 is a flow chart showing a slit scan type fundus photographing process by a fundus camera, in particular, a flow of focus confirmation control. FIG. 11 is an explanatory diagram for explaining a modification of driving of the imaging element by the focus confirmation control section during focus confirmation control; FIG. 10 is an explanatory diagram showing a correspondence relationship between a modified example of illumination light irradiation positions on the fundus (see symbol XIIIA) during focus confirmation control and a focus evaluation image (see symbol XIIIB); FIG. 8 is a front view of another example of light beams incident on the anterior segment of the subject's eye from the illumination system through two paths;

[Overall Configuration of Fundus Camera]
FIG. 1 is a schematic diagram of a fundus camera 10 corresponding to the ophthalmologic apparatus of the present invention. Among the mutually orthogonal XYZ directions in the figure, the X direction is the lateral direction (interpupillary direction of the subject's eye E) with respect to the subject, the Y direction is the vertical direction, and the Z direction is the subject's direction. It is the front-rear direction (also referred to as the working distance direction) parallel to the front direction toward the examiner and the rearward direction away from the examinee.

As shown in FIG. 1, the fundus camera 10 corresponds to the ophthalmologic apparatus of the present invention, and performs slit scan imaging of the fundus Ef of the subject's eye E (hereinafter abbreviated as slit scan imaging). The fundus camera 10 is roughly divided into a camera head 12 (also referred to as a device main body), an operation section 14 , a display section 16 and a control device 18 .

The camera head 12 is provided with various optical systems and the like necessary for slit scan imaging, which will be described later in detail. Although not shown, the camera head 12 is held by a drive mechanism (not shown) so as to be relatively movable in the XYZ directions. As a result, the camera head 12 can be moved relative to the eye E to be inspected in the XYZ directions, so that the camera head 12 can be aligned with the eye E to be inspected.

The operation unit 14 receives input of various operations of the retinal camera 10 , such as an operation to start slit scan imaging, an operation to move the camera head 12 in the XYZ directions, and an operation to set the retinal camera 10 .

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

The control device 18 is an arithmetic processing device such as a computer that executes various kinds of arithmetic processing and control processing. The camera head 12 , the operation section 14 and the display section 16 are connected to the control device 18 . The control device 18 comprehensively controls operations of the camera head 12 and the display unit 16 based on operation instructions input to the operation unit 14 . The control device 18 performs alignment of the camera head 12, focus confirmation control for capturing a focus evaluation image DS (see FIG. 9) indicating the focus state of the illumination system 20 and the light receiving system 40 with respect to the fundus oculi Ef, and focus optics. Various controls and processes including focusing control of the system 36, slit scan photography of the fundus oculi Ef by the camera head 12, and generation and display of the fundus image D are executed.

[Configuration of camera head]
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 part of the fundus oculi Ef with illumination light LS (slit light) via an optical scanner 30 which will be described later. The illumination system 20 includes a light source 22 , a diaphragm 24 , a slit aperture diaphragm 26 , an illumination system lens 28 , a lens 31 , an optical path dividing member 34 and an objective lens 38 . The diaphragm 24, the optical scanner 30, the optical path dividing member 34, and the anterior ocular segment Ea of the subject's eye E are in an optically conjugate relationship.

The light source 22 emits illumination light L. As shown in FIG. As the illumination light L, visible light is used during slit scan imaging of the fundus oculi Ef. External light is used. Visible light may also be used during focus confirmation control. A laser light source, an LED (Light Emitting Diode) light source, a white LED light source, a laser-excited white light source, or the like is used as the light source 22, but is not limited thereto.

The diaphragm 24 includes a diaphragm (for example, an iris diaphragm, an anterior lens diaphragm, etc.) that is optically conjugated or substantially optically conjugated with the anterior segment Ea (cornea and iris) of the eye E to be examined. Not as long. The diaphragm 24 is a light shielding member having a pair of openings 24a symmetrical about the central axis of the light source 22. As shown in FIG. The number and arrangement of the openings 24a are not particularly limited as long as the openings 24a are provided at positions eccentric to the central axis of the light source 22 . The illumination light L that has passed through the diaphragm 24 is incident on 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 aperture 24, and emits this illumination light LS toward the illumination system lens 28. do. The illumination light LS becomes a slit shape (slit light) parallel to the X direction at the fundus position and the fundus conjugate position at the time of focusing. 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 to be movable along the optical path of the illumination light LS by an actuator (not shown). By moving the slit aperture diaphragm 26, the illumination system 20 can be focused on the fundus oculi Ef.

The illumination system lens 28 is composed of one or a plurality of lenses, and emits the illumination light LS incident from the slit aperture stop 26 toward the optical scanner 30 . The lens 31 emits the illumination light LS reflected by the optical scanner 30 toward the optical path dividing member 34 . The lens 31 brings the optical scanner 30 and the optical path splitter 34 into an optically conjugate relationship. The optical path dividing member 34 and the objective lens 38 will be described later.

A projector capable of emitting the illumination light LS may be used as the illumination system 20 . Examples of this projector include an LCD type projector, an LCOS (Liquid crystal on silicon) type projector using a reflective liquid crystal panel, and a projector using a DMD (Digital Mirror Device). In this case, instead of using a fixed mirror, the optical scanner 30 may mimic the optical scanning performed by the optical scanner 30 by changing the pattern of the projector.

The optical scanner 30 is a deflection mechanism capable of one-dimensional deflection (scanning) of the illumination light LS such as a galvanomirror, a resonant mirror, a polygon mirror, and MEMS (Micro Electro Mechanical Systems). It is arranged at the intersection with the optical axis of the lens 31 . The optical scanner 30 can reflect the illumination light LS incident from the illumination system lens 28 toward the lens 31 and deflect the illumination light LS.

The polarization direction and deflection angle of the illumination light LS by the optical scanner 30 are controlled by the controller 18 . 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, here in the Y direction (corresponding to the second direction of the present invention) during slit scan imaging.

The optical path dividing member 34 reflects the illumination light LS incident from the lens 31 and emits it toward the objective lens 38, and also allows the return light LB (described later) incident from the objective lens 38 to pass through and toward the focusing optical system 36. emit. If the optical path splitting member 34 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, Various splitters can be used.

The objective lens 38 irradiates the illumination light LS reflected by the optical path dividing member 34 through the anterior segment Ea (pupil) of the eye E to be examined and onto a part of the fundus oculi Ef. At this time, the illumination light LS is deflected in the Y direction by the optical scanner 30 described above, so that the illumination light LS (slit light) parallel to the X direction scans the fundus Ef in the Y direction. While the illumination light LS is being deflected in the Y direction, the return light LB from the fundus Ef of the eye E irradiated with the illumination light LS is passed through the objective lens 38 and the optical path dividing member 34 to the focusing optical system 36. incident on

The light receiving system 40 includes an objective lens 38, an optical path dividing member 34, a focusing optical system 36, a light receiving system lens 42, and a CMOS imaging element 44 corresponding to the detector of the present invention.

The focus optical system 36 includes one or more lenses (focus lenses) movable along the optical path of the return light LB, and performs focus adjustment 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 focusing 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 (visibility) of the eye E to be examined. The return light LB that has entered the focus optical system 36 from the optical path dividing member 34 enters the light receiving system lens 42 . Note that instead of movably providing one or more 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 system lens 42 is composed of one or a plurality of lenses, and converges the return light LB incident from the focus optical system 36 onto the imaging device 44 .

The imaging element 44 has a light receiving surface 44a on which the return light LB from the light receiving system lens 42 is incident. It has a rolling shutter function that picks up (receives and detects) the return light LB while shifting. During slit scan imaging, the imaging device 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 oculi Ef according to the deflection of the illumination light LS by the optical scanner 30. and outputs an imaging signal of the return light LB to the control device 18 .

[Function of control device]
FIG. 2 is a functional block diagram of the control device 18. As shown in FIG. As shown in FIG. 2, the functions of the control device 18 are implemented using various processors. Various processors include CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), and programmable logic devices [for example, SPLD (Simple Programmable Logic Devices), CPLD (Complex Programmable Logic Device), and FPGAs (Field Programmable Gate Arrays)]. Various functions of the control device 18 may be realized by one processor, or may be realized by a plurality of processors of the same type or different types.

By executing a control program (not shown), the control device 18 controls 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 confirmation control unit 59, and a repetition control. It functions as a unit 61 , a focus control unit 62 and a display control unit 64 . It should be noted that what is described as "--unit" of the control device 18 may be "--circuit," "--device," or "--equipment." That is, what is described as "--unit" may consist of firmware, software, hardware, or a combination thereof.

(Slit scan photography)
First, the functions of the control device 18 relating to slit scan photography will be described. During slit scan imaging, the illumination control section 50, the deflection control section 52, the imaging control section 54, the signal acquisition section 56, the image generation section 58, and the display control section 64 of the control device 18 function.

The illumination control unit 50 controls emission of the illumination light L from the light source 22 , that is, emission of the illumination light LS from the illumination system 20 . The illumination control unit 50 emits illumination light L (visible light) from the light source 22 during slit scan imaging.

FIG. 3 is an explanatory diagram comparing the fundus oculi Ef (see reference numeral 3A) and the light receiving surface 44a (see reference numeral 3B) of the imaging element 44 during slit scan imaging. Reference character R1A in FIG. 3 indicates an illumination region R1A of the illumination light LS within the fundus oculi Ef, and reference character R1B indicates an incident region R1B of the return light LB incident on the light receiving surface 44a. 3 indicates the light receiving region R2B (active exposure region) in the light receiving surface 44a, and the code R2A indicates the imaging range R2A imaged by the light receiving region R2B in the fundus oculi Ef.

In the drawing, the width of the imaging range R2A is greater than the width of the illumination region R1A, and the width of the light receiving region R2B is greater than the width of the incident region R1B, but this is not the only option. That is, the individual positional shapes of the illumination region R1A and the imaging range R2A within the fundus oculi Ef and the individual positional shapes of the incident region R1B and the light receiving region R2B within the light receiving surface 44a are limited to the example shown in FIG. It may be changed as appropriate (the same applies to other drawings).

As shown in FIG. 3 and FIG. 2 already described, 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 to deflect the illumination light LS in the Y direction during slit scan imaging, thereby scanning the fundus Ef in the Y direction with the illumination light LS (slit light).

The illumination region R1A of the illumination light LS within the fundus oculi Ef moves in the Y direction according to the deflection of the illumination light LS in the Y direction (see reference numeral 3A in FIG. 3). Further, according to the movement of the illumination region R1A, the incident region R1B of the return light LB moves in the Y direction within the light receiving surface 44a (see reference numeral 3B in FIG. 3). The control of the optical scanner 30 during focus confirmation control by the deflection control unit 52 will be described later.

The imaging control unit 54 controls driving of the imaging element 44 . During slit scan imaging, the imaging control unit 54 operates during the deflection of the illumination light LS in the Y direction by the optical scanner 30, that is, while the illumination region R1A is moving in the Y direction within the fundus oculi Ef. Rolling shutter driving of the imaging element 44 (driving in the first operation mode of the present invention) is performed.

Specifically, the imaging control unit 54 locally receives light at a position corresponding to the incident region R1B within the light receiving surface 44a in accordance with (synchronously) movement of the incident region R1B within the light receiving surface 44a in the Y direction. Imaging of the return light LB by the region R2B is continuously performed. As a result, the imaging control unit 54 causes the light receiving region R2B to continuously perform imaging of the return light LB while causing the light receiving region R2B to follow the incident region R1B moving in the Y direction within the light receiving surface 44a (symbol 3B).

In other words, within the fundus oculi Ef, the imaging element 44 continuously captures images of the imaging range R2A while causing the local imaging range R2A to follow the illumination area R1A moving in the Y direction (see reference numeral 3A). Since such a rolling shutter drive is a well-known technology, a detailed description is omitted (see Patent Document 1 above).

The signal acquisition unit 56 is wired or wirelessly connected to the imaging device 44 via a communication interface (not shown). During slit scan imaging, the signal acquisition unit 56 sequentially acquires an imaging signal (also referred to as a detection signal or a light receiving signal) from the light receiving region R2B of the imaging device 44 while the illumination light LS is being deflected by the optical scanner 30. get.

FIG. 4 is an explanatory diagram showing an example of the fundus image D generated by the image generator 58. As shown in FIG. As shown in FIG. 4 and FIG. 2 already described, the image generation unit 58 generates the imaging signal acquired by the signal acquisition unit 56 while the illumination light LS is being deflected by the optical scanner 30 during slit scan imaging. , the fundus image D is generated.

The display control unit 64 controls display by the display unit 16 . The display control unit 64 causes the display unit 16 to display the fundus image D generated by the image generation unit 58 during slit scan imaging.

(Focus Confirmation Control and Focus Control)
Next, functions related to focus confirmation control and focus control of the control device 18 will be described. In the present embodiment, prior to slit scan imaging of the fundus oculi Ef by the retinal camera 10, the existing configuration of the retinal camera 10 is used to determine the focused state of the illumination system 20 and the light receiving system 40 with respect to the fundus oculi Ef (hereinafter simply referred to as " (abbreviated as "in-focus state") is evaluated. At this time, in the present embodiment, a state in which the illumination system 20 and the light receiving system 40 are focused on the fundus oculi Ef (hereinafter referred to as a state in which the illumination system 20 and the light receiving system 40 are focused on the fundus oculi Ef) Note that the state of incidence of the illumination light LS on the fundus oculi Ef changes between the out-of-focus state (hereinafter referred to as out-of-focus state) and the out-of-focus state.

FIG. 5 is an explanatory diagram showing a ray diagram (see symbol 5A) of the luminous flux incident on the subject's eye E during focusing, and a front view of the luminous flux (see symbol 5B) incident on the anterior segment Ea. Reference numerals 6A and 6B in FIG. 6 are explanatory diagrams showing ray diagrams of light beams incident on the subject's eye E when out of focus.

As shown in FIGS. 5 and 6, in this embodiment, the diaphragm 24 (see FIG. 1) is in an optically conjugate relationship with the anterior segment Ea. From 20, the luminous flux enters the anterior segment Ea from two different paths (see symbol 5B in FIG. 5).

At the time of focusing, as indicated by reference numeral 5A in FIG. 5, the condensing positions of the light beams match (or substantially match) the fundus oculi Ef, so that each light beam is incident on one region on the fundus oculi Ef. Conversely, as indicated by reference numerals 6A and 6B in FIG. 6, when the focus is out of focus, the condensing positions of the respective light beams are shifted back and forth with respect to the fundus oculi Ef. . Therefore, the in-focus state can be evaluated based on the state of incidence of the illumination light LS on the fundus oculi Ef.

Therefore, the control device 18 performs focus confirmation control in which the return light LB from the fundus Ef irradiated with the illumination light LS is imaged by the imaging element 44 in a state where the deflection angle of the illumination light LS by the optical scanner 30 is fixed. Then, a focus evaluation image DS (see FIG. 9) indicating the focus state is acquired. Then, the control device 18 executes focus control of the focus optical system 36 based on the focus evaluation image DS acquired by the focus confirmation control.

Returning to FIG. 2, during focus confirmation control and focus control, the illumination control unit 50, the deflection control unit 52, the imaging control unit 54, the signal acquisition unit 56, the image generation unit 58, and the focus confirmation control of the control device 18 are controlled. A unit 59, a repetition control unit 61, and a focus control unit 62 function.

The illumination control unit 50 emits illumination light L (infrared light) from the illumination system 20 during focus confirmation control.

The focus confirmation control unit 59 controls the optical scanner 30 via the illumination control unit 50, and controls the imaging element 44 via the imaging control unit 54 to perform focus confirmation control, that is, the focus evaluation image DS ( 9) is executed.

FIG. 7 is an explanatory diagram comparing the fundus oculi Ef (see symbol 7A) and the light-receiving surface 44a (see symbol 7B) of the imaging device 44 when focus confirmation control is executed during focusing. FIG. 8 is an explanatory diagram comparing the fundus oculi Ef (see symbol 8A) and the light-receiving surface 44a (see symbol 8B) of the imaging element 44 when focus confirmation control is executed when out of focus.

As shown in FIGS. 7 and 8, the focus confirmation control unit 59 controls the optical scanner 30 via the deflection control unit 52 to fix the deflection angle of the illumination light LS by the optical scanner 30. The fundus oculi Ef is irradiated with the light LS without scanning. The deflection angle of the illumination light LS at this time is set to an angle that allows the return light LB to enter the middle of the moving path of the light receiving region R2B within the light receiving surface 44a. For example, when the scanning direction of the illumination light LS in the fundus oculi Ef is the Y direction, the focus confirmation control unit 59 causes the illumination light LS to enter the central region (including the substantially central region) of the fundus oculi Ef in the Y direction. The deflection angle of the illumination light LS is controlled so as to

By fixing the deflection angle of the illumination light LS in this manner, the position of the illumination region R1A within the fundus oculi Ef is fixed as indicated by reference numeral 7A in FIG. 7 and reference numeral 8A in FIG. Further, according to the fixed position of the illumination region R1A, the position of the incident region R1B within the light receiving surface 44a, that is, the position of the return light LB on the light receiving surface 44a, as indicated by reference numeral 7B in FIG. 7 and reference numeral 8B in FIG. The position of the pattern image Pi is also fixed.

At this time, as shown in FIG. 5 described above, each light beam of the illumination light LS is incident on one region on the fundus oculi Ef at the time of focusing. The number becomes one (see symbol 7B). On the other hand, as shown in FIG. 6 already described, when the illumination light LS is out of focus, each light beam of the illumination light LS is divided into two regions and enters the fundus oculi Ef. spreads, and splits into two when the degree of out-of-focus is large (see symbol 8B).

In addition, the focus confirmation control unit 59 drives the image sensor 44 via the imaging control unit 54 to perform rolling shutter driving (driving in the second operation mode) to move the light receiving region R2B within the light receiving surface 44a by a predetermined amount. Move along a route (movement pattern) (see symbols 7B and 8B).

In the present embodiment, the second operation mode is set to be the same as the first operation mode during slit scan photography, so the movement path of the light receiving region R2B during focus confirmation control is the same as the movement path during slit scan photography. Although they are set on the same route, there is no particular limitation as long as the incident region R1B is included in the middle of the route. For example, the movement path of the light-receiving region R2B during focus confirmation control may be set narrower than the movement path during slit scan imaging, or may be set to a different path from the movement path during slit scan imaging. The second operating mode may be different from the first operating mode. As a result, the return light LB incident on the light receiving surface 44a can be reliably imaged in the light receiving region R2B.

During focus confirmation control, the signal acquisition unit 56 acquires an imaging signal (corresponding to a detection signal of the present invention) output from the light receiving region R2B of the imaging device 44 while the imaging device 44 is being driven for the rolling shutter. Obtained sequentially.

FIG. 9 is an explanatory diagram showing an example of the focus evaluation image DS generated by the image generator 58 during focusing. FIG. 10 is an explanatory diagram showing an example of the focus evaluation image DS generated by the image generator 58 when out of focus. As shown in FIGS. 9 and 10 and FIG. 2 already described, the image generation unit 58 causes the signal acquisition unit 56 to acquire the A focus evaluation image DS indicating the focus state is generated based on the captured image signal.

As shown in FIGS. 9 and 10, the focus evaluation image DS includes a pattern image Pi of the return light LB whose brightness value is relatively high in the image. The focus evaluation image DS (see FIG. 9) generated during in-focus includes one pattern image Pi, and the focus evaluation image DS (see FIG. 10) generated during out-of-focus includes a spread pattern image. Two pattern images Pi are included if the pattern image Pi is defocused or the degree of defocus is large.

Returning to FIG. 2, the repetition control unit 61 changes the lens position of the focus lens of the focus optical system 36, and controls the focus confirmation control unit 59, the signal acquisition unit 56, and the image acquisition unit 59 for each of a plurality of mutually different lens positions. Repeated control for repeatedly operating the generator 58 is executed. Thereby, a focus evaluation image DS is generated for each of a plurality of lens positions. Note that when the focus optical system 36 includes a variable focus lens instead of the focus lens, the repeat control unit 61 repeats control for each of a plurality of different focal positions of the variable focus lens.

The focus control unit 62 performs focus control of the focus optical system 36 to focus the illumination system 20 and the light receiving system 40 on the fundus oculi Ef. As described above, the focusing of the light receiving system 40 by the focusing 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 (visibility) of the eye E to be examined. . First, the focus control unit 62 illuminates the fundus Ef from the focus evaluation images DS for each lens position of the focus lens (including each focal position of the varifocal lens; the same shall apply hereinafter) generated by repeated control. A focus evaluation image DS photographed with the system 20 and the light receiving system 40 in the most focused state is discriminated. For example, the focus control unit 62 performs the above determination by comparing the number of pattern images Pi included in the focus evaluation image DS for each lens position, the luminance value, the luminance distribution, and the like. Next, the focus control unit 62 controls the focus optical system 36 to move the focus lens to the lens position corresponding to the determined focus evaluation image DS.

Note that instead of performing focus control by the focus control unit 62 based on the focus evaluation images DS for each of a plurality of lens positions, the focus evaluation images DS generated by one focus confirmation control or based on the focus evaluation images DS Focus control by the focus control unit 62 may be performed based on the imaging signal. In this case, the focus control unit 62 adjusts the illumination system 20 and the light receiving system 40 to focus on the fundus oculi Ef based on the number of pattern images Pi, luminance value, luminance distribution (peak, spread), and the like. The focus optical system 36 is driven.

[Action of this embodiment]
FIG. 11 is a flow chart showing the flow of slit scan type fundus photographing processing by the fundus camera 10 configured as described above, particularly focus confirmation control corresponding to the control method of the ophthalmologic apparatus of the present invention.

As shown in FIG. 11, after the subject's face is supported by the face support portion (not shown), when the examiner operates the operation unit 14 to start photographing, the camera head 12 is aligned with the eye E to be examined. is performed in a known manner (step S1). Further, the illumination control unit 50 causes the light source 22 to start emitting illumination light L (infrared light), so that the illumination system 20 irradiates the fundus Ef with the illumination light LS. Then, the focus confirmation control section 59 starts focus confirmation control (step S2).

7 and 8, the focus confirmation control unit 59 controls the optical scanner 30 via the deflection control unit 52 to fix the deflection angle of the illumination light LS by the optical scanner 30. , the position of the illumination region R1A within the fundus oculi Ef is fixed (step S3). In addition, the focus confirmation control unit 59 drives the image sensor 44 via the imaging control unit 54 by rolling shutter driving (driving in the second operation mode) to move the light receiving region R2B within the light receiving surface 44a along a predetermined moving path. to move (step S4). Note that steps S3 and S4 correspond to the focus confirmation control step of the present invention.

Simultaneously with the start of the rolling shutter drive of the imaging device 44, the signal acquisition unit 56 starts acquiring the imaging signal from the imaging device 44 (step S5).

Thereafter, the processes of steps S4 and S5 are repeatedly executed until the rolling shutter driving of the imaging element 44 is stopped, that is, until the movement of the light receiving region R2B along the moving path within the light receiving surface 44a is completed. (NO in step S6). As a result, the light receiving region R2B overlaps the incident region R1B (pattern image Pi) while moving within the light receiving surface 44a, and the return light LB is captured by the light receiving region R2B. An imaging signal of light LB is acquired.

When the rolling shutter drive of the imaging device 44, that is, the movement of the light receiving region R2B within the light receiving surface 44a is completed (YES in step S6), the image generation unit 58 detects that the signal acquisition unit 56 is Based on the acquired imaging signal, the focus evaluation image DS as shown in FIGS. 9 and 10 is generated (step S7).

When the focus evaluation image DS is generated by the image generation unit 58, the repetition control unit 61 moves the lens position of the focus lens of the focus optical system 36, and then repeats the processing from step S4 to step S7. (YES in step S8). As a result, focus evaluation images DS corresponding to lens positions of different focus lenses are generated.

Similarly, the repeat control unit 61 performs repeat control to repeatedly execute the above-described steps S4 to S7 for each lens position while moving the lens position of the focus lens of the focus optical system 36 . As a result, a focus evaluation image DS is generated for each lens position.

When the focus evaluation images DS for all lens positions have been generated (NO in step S8), the focus control unit 62 controls the illumination system 20 for the fundus oculi Ef based on the focus evaluation images DS for each lens position. And the focus evaluation image DS photographed with the light receiving system 40 in the most focused state is discriminated. Then, the focus control unit 62 performs focus control to move the focus lens of the focus optical system 36 to the lens position corresponding to the determined focus evaluation image DS (step S9). As described above, the focus control unit 62 may perform focus control based on the focus evaluation image DS generated by one focus confirmation control, in which case step S8 is omitted. .

When the focus control by the focus control unit 62 is completed, the illumination control unit 50, the deflection control unit 52, the imaging control unit 54, the signal acquisition unit 56, the image generation unit 58, and the display control unit 64 of the control device 18 operate. Then, the slit scan photographing of the fundus oculi Ef shown in FIG. 3 is executed (step S10). The fundus image D captured by this slit scan photography is displayed on the display section 16 by the display control section 64 .

[Effect of this embodiment]
As described above, in the fundus camera 10 of the present embodiment, by performing focus confirmation control for photographing the fundus oculi Ef with the deflection angle of the illumination light LS fixed, the focus evaluation image DS or An imaging signal that serves as a basis for this can be obtained, and the in-focus state can be evaluated with high accuracy. In addition, this focus confirmation control can be executed using the existing slit scan photographing function of the retinal camera 10, and only by changing the control program of the retinal camera 10, no additional configuration is required. As a result, the in-focus state can be evaluated at low cost and with high accuracy.

[Modified Example of Drive of Imaging Device During Focus Confirmation Control]
12A and 12B are explanatory diagrams for explaining a modification of the drive of the image sensor 44 by the focus confirmation control section 59 during focus confirmation control. 12 indicates the fundus Ef, and XIIB indicates the light-receiving surface 44a of the imaging device 44. As shown in FIG.

In the above embodiment, the light receiving region R2B is moved along a predetermined movement path within the light receiving surface 44a during focus confirmation control, but the light receiving region R2B may not be moved. For example, as shown in FIG. 12, the focus confirmation control unit 59 drives the image sensor 44 in an operation mode (third operation mode of the present invention) different from that in the above-described embodiment via the imaging control unit 54 to receive light. The position of the light receiving region R2B within the surface 44a may be fixed. In this case, the fixed position of the light receiving region R2B is a position where the optical scanner 30 can detect the return light LB (pattern image Pi) from the fixed illumination region R1A within the fundus oculi Ef.

When the position of the light receiving region R2B within the light receiving surface 44a is fixed, the incident region R1B (pattern image Pi) within the light receiving surface 44a expands when out of focus, or when the degree of out of focus is large. is divided into two (see FIG. 8), the width of the light receiving region R2B in the Y direction may be wider than in the above embodiment.

Even if the position of the light-receiving region R2B within the light-receiving surface 44a is fixed during focus confirmation control, the focus evaluation image DS as shown in FIGS. Therefore, the same effects as those of the above embodiment can be obtained.

[Modified Example of Irradiation Position of Illumination Light During Focus Confirmation Control]
FIG. 13 is an explanatory diagram showing a correspondence relationship between a modified example of the irradiation position of the illumination light LS with respect to the fundus oculi Ef (see symbol XIIIA) and the focus evaluation image DS (see symbol XIIIB) during focus confirmation control. . In the above embodiment, the central region of the fundus oculi Ef is irradiated with the illumination light LS during focus confirmation control. It may be set outside the central area. In this case also, as indicated by XIIIB in FIG. 13, the focus evaluation image DS including the pattern image Pi is obtained, so that the same effect as in the above embodiment can be obtained.

[others]
FIG. 14 is a front view of another example of light beams incident on the anterior segment Ea of the eye to be examined E from the illumination system 20 through two paths. In the above-described embodiment, an example of the light beams incident on the anterior segment Ea from two paths is indicated by reference numeral 5A in FIG. Well, you can change it to another shape.

In the above-described embodiment, light beams are incident on the anterior segment Ea from the illumination system 20 through two paths. , the number of light beams incident on the anterior segment Ea and the incident paths thereof may be changed as appropriate.

In each of the above-described embodiments, the CMOS imaging device 44 having a rolling shutter function is used as the detector of the present invention, but various other known detectors may be used.

In each of the above embodiments, the fundus oculi Ef is irradiated with the illumination light LS, but any shape of light such as line light, spot light, or dot light may be irradiated. When spot light or dot light is irradiated from the retinal camera 10 to the fundus oculi Ef, a device capable of two-dimensionally deflecting the spot light or the like is used as the optical scanner 30, and the spot light or the like is used to illuminate the fundus oculi Ef two-dimensionally. You can scan.

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 parts can be changed as appropriate.

In each of the above-described embodiments, the fundus camera 10 that photographs the fundus oculi Ef of the eye E to be examined has been described as an example. The present invention can be applied to various ophthalmologic apparatuses capable of deflecting the illumination light (including the excitation light) applied to a part of the site to be observed.

10 fundus camera 12 camera head 14 operation unit 16 display unit 18 control device 20 illumination system 22 light source 24 diaphragm 24a aperture 26 slit aperture diaphragm 28 illumination system lens 30 optical scanner 31 lens 34 optical path dividing member 36 focusing 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 Focus confirmation control unit 61 Repetition control unit 62 Focus control unit 64 Display control unit D Fundus image DS Focus evaluation image E Eye to be examined Ea Anterior segment Ef Fundus L Illumination light LB Return light LS Illumination light Pi Pattern image R1A Illumination region R1B Incident region R2A Imaging range R2B Light receiving region

Claims (9)

an illumination system that irradiates illumination light onto a portion of an observed region of an eye to be inspected;
an optical scanner that deflects the illumination light emitted from the illumination system onto the site to be observed and moves an illumination area of the illumination light within the site to be observed;
a light receiving system having a detector that detects return light from the illumination area that moves within the observed site in accordance with the deflection of the illumination light while the optical scanner deflects the illumination light;
a focus confirmation control unit that controls the optical scanner to perform focus confirmation control that causes the detector to detect the return light from the illumination area in a state where the illumination area is fixed within the site to be observed; ,
An ophthalmic device comprising: a focus optical system provided in the optical path of the return light;
a focus control unit that performs focus control of the focus optical system based on the detection signal of the return light detected by the detector in the focus confirmation control;
The ophthalmic device of claim 1, comprising: an image generation unit that generates a focus evaluation image indicating a focus state of the illumination system and the light receiving system with respect to the observed site based on the detection signal;
The ophthalmologic apparatus according to claim 2, wherein the focus control section performs the focus control based on the focus evaluation image generated by the image generation section. The focus optical system has a focus lens,
a repeat control unit that repeatedly operates the focus confirmation control unit and the image generation unit for each of a plurality of different lens positions of the focus lens;
4. The ophthalmologic apparatus according to claim 3, wherein the focus control section performs the focus control based on the focus evaluation image for each lens position generated by the image generation section. The detector has a light-receiving surface on which the return light is incident, and the return light is detected within the light-receiving surface with respect to an incident area of the return light that moves within the light-receiving surface according to the movement of the illumination area. A first operation mode in which the return light is continuously detected in the light receiving area while following the local light receiving area that detects a second mode of operation in which the
the return light from the illumination area fixed by the optical scanner in the focus confirmation control is incident in the middle of the moving path of the light receiving area;
The ophthalmologic apparatus according to any one of claims 1 to 4, wherein the focus confirmation control section drives the detector in the second operation mode. The detector has a light-receiving surface on which the return light is incident, and the return light is detected within the light-receiving surface with respect to an incident area of the return light that moves within the light-receiving surface according to the movement of the illumination area. A first operation mode in which the return light is continuously detected in the light receiving area while following the local light receiving area that detects the return light from the illumination area fixed by the optical scanner. a third mode of operation that fixes the light-receiving region at a detectable position in the light-receiving surface;
The ophthalmologic apparatus according to any one of claims 1 to 4, wherein the focus confirmation control section drives the detector in the third operation mode. When the directions perpendicular to the optical axis of the illumination system and mutually orthogonal are defined as the first direction and the second direction, the illumination system emits slit light parallel to the first direction as the illumination light to the site to be observed. irradiate to
The ophthalmologic apparatus according to any one of claims 1 to 6, wherein the optical scanner deflects the slit light in the second direction. a diaphragm that is provided in the illumination system and that is optically conjugate with the anterior segment of the subject's eye, and that has a plurality of apertures at positions decentered with respect to the illumination optical axis of the illumination system; 8. An ophthalmic device according to any one of claims 1 to 7. an illumination system that irradiates illumination light onto a portion of an observed region of an eye to be inspected;
an optical scanner that deflects the illumination light emitted from the illumination system onto the site to be observed and moves an illumination area of the illumination light within the site to be observed;
a light receiving system having a detector that detects return light from the illumination area that moves within the observed site in accordance with the deflection of the illumination light while the optical scanner deflects the illumination light;
In a control method for an ophthalmic device comprising
A control method for an ophthalmologic apparatus, comprising a focus confirmation control step of controlling the optical scanner to cause the detector to detect the return light from the illumination area while the illumination area is fixed within the observed site.

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