JP7421062B2 - fundus imaging device - Google Patents

Description

The present disclosure relates to a fundus imaging device.

2. Description of the Related Art Conventionally, as a type of fundus photographing device, a device is known that captures a frontal image as a fundus image by scanning light on the fundus.

BACKGROUND ART As a scanning type fundus photographing device, a device equipped with a confocal optical system is known (see, for example, Patent Document 1). As a confocal optical system, for example, one in which an aperture for removing noise light is arranged at a conjugate position of the fundus on a light receiving optical path is known.

For example, in Patent Document 1, as a result of acquiring a plurality of fundus images while changing the focus position and comparing the imaging states of each fundus image, the focus position when obtaining the captured image is set to a suitable imaging state. Disclosed is a device for adjusting the position to become .

JP2009-291253A

However, conventionally, when there is a height difference in the fundus due to disease or curvature, it has been difficult to adjust the focus appropriately.

A technical problem of the present disclosure is to solve at least one of the problems of the prior art and to provide a fundus photographing device that can easily adjust focus and photograph a fundus image.

A fundus photographing device according to a first aspect of the present disclosure includes a light emitting section that emits observation light and photographing light, and an irradiation optical system that irradiates light from the light emitting section to the fundus of an eye to be examined. an irradiation optical system having a scanning means for scanning the light above, a light receiving optical system having a light receiving element that outputs a light reception signal by receiving the return light of the light from the fundus; a focus adjustment section that adjusts a focus position in at least one of the light receiving optical systems; and a control means, the control means being configured to generate a fundus image based on the light receiving signal from the light receiving element based on the light receiving signal of the return light from the observation light. A fundus photographing apparatus that obtains an observation image based on a light receiving signal of the return light caused by the photographing light, and a photographic image based on a light reception signal of the return light from the photographing light, wherein the illumination depth in at least one of the irradiation optical system and the light reception optical system is set to a first and a second illumination depth that is shallower than the first illumination depth, the control means is configured to adjust the illumination depth to the second illumination depth. The focus position is adjusted based on the observation image with the illumination depth set to the second illumination depth, and the captured image is adjusted based on the observation image with the illumination depth set to the second illumination depth. Shoot with the illumination depth set to 1 .

According to the present disclosure, it is easy to properly adjust focus and photograph a fundus image.

1 is a diagram showing a schematic configuration of an optical system of a fundus photographing device 1. FIG. 2 is a diagram showing a schematic configuration of the optical system of the fundus photographing device 1 when a lens attachment 3 is attached. FIG. 1 is a block diagram showing the electrical configuration of a fundus photographing device 1. FIG. FIG. 3 is a diagram illustrating an example of a fundus image photographed with the size of the passage area set to a first size. FIG. 7 is a diagram illustrating an example of a fundus image taken with the size of the passage area set to a second size and the focus position set on the retinal surface side. FIG. 7 is a diagram illustrating an example of a fundus image taken with the size of the passage area set to a second size and the focus position set on the choroid side. It is a flowchart showing the flow of photographing operation in an example. FIG. 7 is a diagram illustrating an observation image displayed on a monitor 80 to accept an operation for setting an observation region.

"overview"
The fundus imaging device (see FIGS. 1 to 3) exemplified in the present disclosure includes a light emitting section, an irradiation optical system, a light receiving optical system, a focus adjustment section, an illumination depth adjustment section, and a control section (control means). , is provided. The fundus photographing device is a scanning type device. The fundus photographing device may be, for example, a two-dimensional scan type device that scans a spot-shaped light beam two-dimensionally on the fundus, or a slit-shaped light beam that scans in a direction intersecting the longitudinal direction of the slit. It may be a slit scan (also called line scan) type device.

The light emitting section emits observation light and photographing light. The observation light and the photographing light may have different wavelength bands. For example, the observation light may be infrared light, and the photographing light may be visible light. Further, either the observation light or the photographing light may be selectively emitted from the light emitting section.

The irradiation optical system irradiates the fundus of the eye to be examined with light from the light emitting section. Further, the irradiation optical system includes a scanning section (also referred to as a scanning means or optical scanner) that scans light on the fundus of the eye.

The light receiving optical system has at least a light receiving element.

The light-receiving element outputs a light-receiving signal by receiving returned light (observation light and illumination light) from the fundus of the eye. A fundus image (frontal image of the fundus) is photographed based on the signal from the light receiving element.

The focus adjustment section adjusts the focus position in the irradiation optical system and the light receiving optical system. For example, the focus adjustment section may be equipped with a movable lens, a variable focus lens such as a liquid crystal lens, or an optical system that can change the optical path length. It may be something like that. The optical system capable of changing the optical path length may be, for example, one or more lenses, mirrors, or a combination thereof.

The illumination depth adjustment section is capable of switching the illumination depth (also referred to as depth of field) in at least one of the irradiation optical system and the light reception optical system. The illumination depth may be switched between at least a first illumination depth and a second illumination depth that is shallower than the first illumination depth.

The deeper the illumination depth, the easier it is to acquire a fundus image with a larger amount of information in the depth direction (see FIG. 4). On the other hand, the deeper the illumination depth, the less the change in image quality with respect to change in focus position. On the other hand, when the illumination depth is the shallower second illumination depth, the change in image quality with respect to the change in focus position becomes more clear (see FIGS. 5 and 6).

The illumination depth adjustment section may be, for example, a light restriction section described below or a beam diameter switching section.

The light restriction section is arranged at a position conjugate with the fundus in the light receiving optical system. The light restriction section restricts a region (hereinafter referred to as a passage region) through which the return light guided to the light receiving element passes. The light restriction section may be a diaphragm (so-called confocal diaphragm). In the spot scan type, for example, a pinhole may be used as the light restriction part. Furthermore, in the slit scan type, the slit may be used as a light restriction section. Further, as another configuration of the light restriction section, one in which the light receiving element and the light restriction section are integrated can be considered. In this case, the area that is effectively exposed on the light-receiving surface of the light-receiving element may be controllable. Such a configuration may be, for example, an electronic shutter or a liquid crystal shutter. Furthermore, in the case of a slit scan type optical system, an integrated configuration of the light receiving element and the light limiting section may be realized by utilizing a rolling shutter function in CMOS.

Note that in the present disclosure, "conjugate" is not necessarily limited to a perfect conjugate relationship, and includes "substantially conjugate". For example, the light restricting section may be placed at a position shifted from a completely conjugate position of the fundus within a range permitted in relation to the purpose of use of the fundus image (for example, observation, analysis, etc.).

In this embodiment, the light restriction section sets the size of the passage area to a first size corresponding to the first illumination depth and a second size narrower than the first size and corresponding to the second illumination depth. It is possible to switch between In this case, the size of the passage area may be switched by selectively arranging at least two light restricting parts having different sizes of passage areas on the light receiving optical path. Furthermore, the size of one passage area of the light restriction section may be switchable in at least two stages.

The beam diameter switching section changes the beam diameter of the light irradiated from the irradiation optical system to the subject's eye into a first beam diameter corresponding to the first illumination depth and a second beam diameter that is thicker than the first beam diameter. and a corresponding second beam diameter. The beam diameter switching section may be, for example, a variable beam expander arranged in the irradiation optical system. In this case, the variable beam expander may be placed between the light emitting section and the scanning section.

The control unit is a processor that controls various operations of the fundus photographing device. The control unit may be configured by, for example, a CPU, a RAM, a ROM, and the like.

The control unit executes illumination depth control processing. In the illumination depth control process, the illumination depth is changed at least between when adjusting the focus position based on the observed image and when photographing the captured image.

The "observation image" here is a fundus image generated based on a light reception signal of return light from the observation light. Further, the "photographed image" is a fundus image generated based on a light reception signal of return light from the photographic light.

When adjusting the focus position based on the observed image, a shallower second illumination depth is set. As a result, compared to the case where the first illumination depth is set, the change in image quality with respect to a change in focus position becomes larger (for example, FIG. 4⇒FIG. 5, FIG. 6). As a result, in each case, when there is a height difference in the fundus area that is the imaging range due to a disease, or when there is a height difference due to curvature of the fundus, the area that is in focus on the fundus area. can be easily confirmed through observation images and photographed images.

Further, when acquiring a photographed image, by setting the illumination depth to the first illumination depth, it becomes easier to acquire a fundus image with a larger amount of information in the depth direction. At this time, if the illumination depth switching section is a light restriction section, the size of the passage area becomes wider, so that the light reception efficiency becomes higher. As a result, brighter captured images are more likely to be captured (see FIG. 4). Furthermore, when the illumination depth switching section is a beam diameter adjustment section, the beam diameter becomes larger, making it easier to capture a fundus image with better resolution.

Furthermore, the control unit may further execute focus control processing. In the focus control process, the control unit sequentially acquires observation images with the second illumination depth set, and drives the focus adjustment unit based on information regarding the imaging state detected from the observation images. This makes it easier to capture a photographed image in which the focus is properly adjusted with respect to the fundus.

The control unit may execute a setting process to set a part of the imaging range as an observation region. Furthermore, in the focus control process described above, the control section may drive the focus adjustment section based on information regarding the imaging state at the observation site. Thereby, a fundus image whose focus has been appropriately adjusted with respect to the observed region can be obtained as a photographed image.

The observation site may be set, for example, based on a setting operation by the examiner. In this case, in the setting process, the control unit may accept the operation for setting the observation region, and may also set the observation region based on the setting operation. The setting operation may be an operation of specifying an observed region on the observed image. Thereby, it is possible to capture a fundus image in which the focus is appropriately adjusted for the desired observation site specified by the examiner from the observation image.

Furthermore, the observation site may be set based on, for example, position information that specifies the observation site on the observation image. The position information may indicate, for example, a diseased area or the like identified based on the test results of another fundus examination device (for example, OCT, perimetry, etc.). Alternatively, it may indicate a diseased area identified in a past examination. In these cases, the position information may be obtained from a memory accessible from the control unit.

The ophthalmologic imaging device may be capable of imaging the subject's eye at a second angle of view that is 90° or more (90° or more at the center of the pupil). In this case, for example, an objective optical system with a photographing angle of view of 90° or more may be provided between the operation unit and the eye to be examined. Here, the photographing angle of view indicates the photographing range of the fundus image.

The wider the angle of view, the greater the height difference due to the curvature of the fundus, and therefore the illumination depth control processing is more useful.

"Example"
Hereinafter, a typical embodiment of the present invention will be described with reference to the drawings. First, with reference to FIGS. 1 to 3, the overall configuration of a fundus photographing apparatus 1 (hereinafter referred to as the apparatus 1) will be described. In this embodiment, the device 1 has an SLO (Scanning Light Ophthalmoscope: SLO) configuration. The present device 1 is a device that captures a frontal image of the fundus Er of the eye E to be examined. The present device 1 scans light on the fundus Er and receives return light from the fundus Er, thereby acquiring a frontal image of the fundus Er.

In the following description, the apparatus 1 obtains a fundus image by two-dimensionally scanning light condensed onto a spot on the observation surface based on the operation of a scanning section (optical scanner). However, the present invention is not necessarily limited to this, and the present device 1 may be a so-called slit scan type device. In this case, a slit-shaped light beam is scanned on the observation surface.

<Optical system>
The optical system provided in the present device 1 will be explained with reference to FIG. As shown in FIG. 1, the apparatus 1 includes an irradiation optical system 10 and a light receiving optical system 20. This apparatus 1 uses these optical systems 10 and 20 to capture a fundus image.

The present apparatus 1 of this embodiment switches the photographing angle of view by switching the lens configuration in the objective optical section. Specifically, by attaching and detaching the lens attachment 3 (see FIG. 2), the photographing angle of view is selectively switched to one of two predetermined photographing angles of view. Here, the narrower photographing angle of view is referred to as a "first angle of view", and the wider photographing angle of view is referred to as a "second angle of view". For example, the first angle of view may be less than 90°, and the second angle of view may be greater than or equal to 90°. For example, the first angle of view may be about 45° to 60°, and the second angle of view may be about 90° to 150°.

First, with reference to FIG. 1, the optical system when the photographing angle of view is the first angle of view will be described. In this embodiment, when the lens attachment 3 (see FIG. 2) is not attached, the photographing angle of view is set to the first angle of view.

<Irradiation optical system>
The irradiation optical system 10 includes a scanning section 16 and an objective optical section 17. Objective optical section 17 includes at least one lens. Further, as shown in FIG. 1, the irradiation optical system 10 further includes a light emitting section 11, a collimating lens 12, a perforated mirror 13, a lens 14 (in this embodiment, a part of the focus adjustment section 40), and a lens 15.

The light emitting section 11 is a light source of the irradiation optical system 10. In this embodiment, the light from the light emitting section 11 is used as observation light and photographing light. The light emitting section 11 of this embodiment can emit light of multiple colors simultaneously or selectively. As an example, in this embodiment, the light emitting unit 11 emits light of four colors in total: three colors in the visible range of blue, green, and red, and one color in the infrared range. Light of each color can be emitted simultaneously in any combination. The light emitting section 11 may be formed including, for example, a laser diode (LD), a superluminescent diode (SLD), and the like.

Hereinafter, unless otherwise specified, in this embodiment, infrared light is used as observation light, and visible light is used as photographing light.

The return light from the eye E to be examined relative to the light emitted from the light emitting unit 11 may be, for example, light reflected by the tissue of the eye E to be examined. Further, the light from the light emitting section 11 may be light (for example, fluorescence, etc.) emitted from the tissue based on irradiation.

However, for convenience of explanation, in the following explanation, unless otherwise specified, the light of each color emitted from the light emitting section 11 will be explained as being used for photographing a reflected image using fundus reflected light.

Any or all of an infrared image, a color image, a red-free image, a monochromatic visible image, etc. may be photographed as the reflection image.

In this embodiment, the light emitted from the light emitting section 11 is guided to the fundus Er along the light path shown in FIG. In other words, the light from the light emitting section 11 passes through the collimating lens 12 , an opening formed in the perforated mirror 13 , passes through the lenses 14 and 15 , and then heads toward the scanning section 16 . The laser beam reflected by the scanning unit 16 passes through the dichroic mirror 51 and the objective optical unit 17, and then is irradiated onto the fundus Er of the eye E to be examined. As a result, the light emitted from the light emitting section 11 is reflected and scattered by the fundus Er. This light (that is, fundus reflected light) is emitted from the pupil as return light.

The scanning section 16 (also referred to as "optical scanner") is a unit for scanning the fundus Er with the laser light emitted from the light emitting section 11. In the following description, unless otherwise specified, it is assumed that the scanning unit 16 includes two optical scanners whose scanning directions are different from each other. That is, it includes an optical scanner 16A for main scanning (for example, for scanning in the X direction) and an optical scanner 16B for sub-scanning (for example, for scanning in the Y direction).

The objective optical section 17 is an objective optical system of the apparatus 1. The objective optical section 17 is used to irradiate the eye E to be examined with the light scanned by the scanning section 16 and guide it to the fundus Er. For this purpose, the objective optical section 17 forms a turning point P around which the light passing through the scanning section 16 is turned. The turning point P is formed on the reference optical axis L1 of the irradiation optical system 10 at a position that is optically conjugate with the scanning section 16 with respect to the objective optical section 17. In FIG. 1, the objective optical section 17 of the present apparatus 1 is shown as a refractive system, but it is not necessarily limited to this, and may be a reflective system.

The laser beam that has passed through the scanning section 16 passes through the objective optical section 17, passes through the pivot point P, and is irradiated onto the fundus Er. Therefore, the laser beam that has passed through the objective optical section 17 is rotated around the rotation point P as the scanning section 16 operates. As a result, in this embodiment, the laser beam is scanned two-dimensionally on the fundus Er. The laser light irradiated to the fundus Er is focused at a focusing position (for example, the retinal surface).

<Light receiving optical system>
Next, the light receiving optical system 20 will be explained. The light receiving optical system 20 has one or more light receiving elements. For example, as shown in FIG. 1, the light receiving optical system 20 may include a plurality of light receiving elements 25, 27, and 29. In this case, the return light from the fundus Er is received by at least one of the light receiving elements 25, 27, and 29.

As shown in FIG. 1, the light receiving optical system 20 in this embodiment may share the members arranged from the objective optical section 17 to the perforated mirror 13 with the irradiation optical system 10. In this case, the return light from the fundus Er is guided up the optical path of the irradiation optical system 10 to the perforated mirror 13. The perforated mirror 13 removes at least a portion of the noise light reflected by the cornea of the eye E and the optical system inside the device (for example, the lens surface of the objective lens system, etc.), while at the same time filtering out light from the fundus Er. The light is guided to an independent optical path of the light receiving optical system 20.

The light receiving optical system 20 of this embodiment includes a lens 21, a light restriction section 23, and a light separation section (light separation unit) 30 in the reflection optical path of the perforated mirror 13. Furthermore, lenses 24, 26, and 28 are provided between the light separating section 30 and each of the light receiving elements 25, 27, and 29.

The light restriction section 23 is arranged at a fundus conjugate position on the light receiving optical path. As shown in FIG. 1, the light restriction section 23 restricts a region (hereinafter referred to as a passage region) through which the return light guided to the light receiving element passes.

As shown in FIG. 1, the light restriction section 23 is a rotating disk in which a plurality of apertures of different sizes are formed as confocal apertures. As an example, four openings 23a to 23d are formed. Each aperture regulates the area through which the returned light passes. The center of rotation of the light restriction section 23 is offset with respect to the optical axis L2 (the reference optical axis in the independent optical path of the light receiving optical system 20). 23a to 23d are formed at positions where the optical axis L2 passes. By rotating the light restricting section 23 by the motor 32, one of the openings 23a to 23d is selectively arranged on the optical axis L2. A portion of the returned light that has passed through the aperture on the optical axis L2 is guided to the light receiving elements 25, 27, and 29, and the rest is blocked by the rotary disk. In this embodiment, the size of the passage area is changed by switching which one of the apertures 23a to 23d is arranged on the optical axis L2. In this embodiment, the illumination depth is thereby adjusted.

In this embodiment, the apertures 23a and 23b are provided as confocal apertures for the first angle of view, and the apertures 23c and 23d are provided as confocal apertures for the second angle of view.

The opening 23a is used as a passage area of the first size in this embodiment. In this embodiment, the first angle of view is used when photographing a fundus image. Further, the opening 23b is smaller than the opening 23a. In this embodiment, the opening 23b is used as a passage area of the second size. That is, it is used when adjusting focus in the case of the first angle of view.

Further, the opening 23d is used as a passage area of the third size. That is, it is used when adjusting the focus in the case of the second angle of view. The aperture 23c is used when photographing a fundus image in the case of the second angle of view.

The light separation unit 30 separates light from the fundus Er. In this embodiment, the light from the fundus Er is wavelength-selectively separated by the light separation unit 30. Further, the light separating section 30 may also serve as a light branching section that branches the optical path of the light receiving optical system 20. For example, as shown in FIG. 1, the light separation section 30 may include two dichroic mirrors (dichroic filters) 31 and 32 having different light separation characteristics (wavelength separation characteristics). The optical path of the light receiving optical system 20 is branched into three by two dichroic mirrors 31 and 32. Furthermore, one of the light receiving elements 25, 27, and 29 is arranged at the end of each branched optical path.

For example, the light separation unit 30 separates the wavelengths of light from the fundus Er, and causes the three light receiving elements 25, 27, and 29 to receive light in mutually different wavelength ranges. For example, the light receiving elements 25, 27, and 29 may receive light of three colors, blue, green, and red, one color at a time. In this case, a color image may be acquired from the light reception results of each of the light receiving elements 25, 27, and 29. Further, the light separation unit 30 may cause one of the light receiving elements to receive the fundus reflected light in the infrared region. An infrared image may be acquired based on the signal from this light receiving element.

Here, the spectral characteristics of the light separation section 30 will be explained as an example. In the embodiment, the dichroic mirror 31 reflects at least red light and transmits light in other wavelength ranges. That is, the fundus reflected light for the red illumination light is received by the light receiving element 25.

Furthermore, the dichroic mirror 32 reflects at least green light and transmits light in other wavelength ranges. The light receiving element 29 placed on the reflection optical path of the dichroic mirror 32 receives the fundus reflected light for the green illumination light.

Furthermore, the light receiving element 29 placed in the transmission optical path of the dichroic mirror 32 receives blue light and infrared light. Therefore, the fundus reflected light for the blue illumination light is received by the light receiving element 29. Further, the fundus reflected light of the infrared light emitted from the light emitting section 11 is received by the light receiving element 29 .

<Viewing angle switching section>
Next, with reference to FIG. 2, an optical configuration when the photographing angle of view is a second angle of view which is a wider angle of view will be shown. In this embodiment, the lens attachment 3 is disposed between the objective optical section 17 and the eye E to be examined, thereby configuring the objective optical section 18 for photographing at the second angle of view. The lens attachment 3 of this embodiment has at least one lens. The photographing angle of view of the objective optical section 18 is the second angle of view.

<Anterior segment observation optical system and alignment index projection optical system>
Further, the ophthalmologic imaging device may include either an anterior segment observation optical system or an alignment index projection optical system (both not shown). The anterior segment observation optical system is used to obtain an anterior segment observation image based on a frontal image of the anterior segment. The alignment index projection optical system projects an alignment index that serves as a reference for alignment adjustment onto the cornea of the eye to be examined.

<Control system>
Next, the control system of this device 1 will be explained with reference to FIG. Each part of the apparatus 1 is controlled by a control section 70. The control unit 70 is a processing device (processor) that includes an electronic circuit that performs control processing for each section of the device 1 and arithmetic processing. The control unit 70 is implemented by a CPU (Central Processing Unit), a memory, and the like. The control unit 70 is electrically connected to the storage unit 71 via a bus or the like. Further, the control section 70 is electrically connected to each section such as the light emitting section 11, the light receiving elements 25, 27, and 29, the scanning section 16, the motor 23e, the actuator 40a, the input interface 75, and the monitor 80.

The storage unit 71 stores various control programs, fixed data, and the like. In this embodiment, a shooting control program and the like, which will be described later, are stored in the storage unit 71. Furthermore, temporary data and the like may be stored in the storage unit 71. Images obtained by the present device 1 may be stored in the storage unit 71. However, the present invention is not necessarily limited to this, and images obtained by the apparatus 1 may be stored in an external storage device (for example, a storage device connected to the control unit 70 via LAN and WAN).

The control unit 70 forms a fundus image based on the light reception signals output from the light reception elements 25, 27, and 29, for example. More specifically, the control unit 70 forms a fundus image in synchronization with the optical scanning by the scanning unit 16. For example, the control unit 70 transmits at least one frame (in other words, one) fundus image to the (light receiving element) every time the sub-scanning optical scanner 16B reciprocates n times (n is an integer of 1 or more). form). In the following description, unless otherwise specified, it is assumed for convenience that one frame of the fundus image based on one round trip of the optical scanner 16B for sub-scanning is formed for each round trip of the optical scanner 16B. In this embodiment, since three light receiving elements 25, 27, and 29 are provided, the control unit 70 outputs up to three types of images based on the signals from the respective light receiving elements 25, 27, and 29 for sub-scanning. is generated each time the optical scanner 16B makes one round trip.

The control unit 70 may display a plurality of frames of fundus images sequentially formed based on the operation of the apparatus as described above on the monitor 80 in chronological order as observation images. The observation image is a moving image consisting of fundus images acquired substantially in real time.

Further, the control unit 70 photographs (captures) the fundus image as a photographed image (captured image) based on the photographing trigger. The photographed image is stored in a storage medium. The storage medium in which the photographed image is stored may be a nonvolatile storage medium (for example, a hard disk, a flash memory, etc.).

The input interface 75 is an operation unit that receives operations from the examiner. For example, a touch panel, a mouse, a keyboard, etc. may be used as the input interface 75.

<Operation explanation>
Next, the photographing operation of the apparatus 1 will be described with reference to the flowchart in FIG.

In advance, the lens attachment 3 is attached to and removed from the device 1, and the photographing angle of view of the device 1 is set (S1). The attachment/detachment state of the lens attachment 3 may be manually input into the apparatus 1 by the examiner. Further, a sensor for detecting the attachment/detachment state of the lens attachment 3 may be provided in the device 1, and a detection signal from the sensor may be input to the device 1.

Next, alignment of the device with respect to the eye E to be examined is performed (S2). During alignment, the examiner fixes the subject's face on the face support unit (not shown) of the present device 1. In addition, the subject's eye E is caused to fixate using a fixation target projection unit (not shown) of the present device 1 . Furthermore, an anterior segment observation optical system (not shown) may be controlled to generate and display an anterior segment observation image. Further, the control unit 70 may project the alignment index onto the cornea from an alignment index projection optical system (not shown). Thereby, the alignment index image is superimposed on the anterior segment observation image. Based on the anterior segment observation image and the alignment index image, the positional relationship of the optical system (irradiation optical system 10 and light receiving optical system 20) with respect to the eye to be examined is adjusted. The alignment may be manual alignment or automatic alignment. The alignment adjustment is completed by moving the optical system to a positional relationship (alignment allowable range) where a fundus image can be captured.

After the optical system is moved to the alignment tolerance range, the control unit 70 starts acquiring and displaying a fundus observation image (S3).

Next, the control unit 70 arranges the larger aperture of the two apertures corresponding to the photographing angle of view on the optical axis L2 (S4). That is, the motor 23e is driven to arrange the aperture 23a on the optical axis L2 when the photographing angle of view is the first angle of view, and the aperture 23c when the photographing angle of view is the second angle of view.

In the present embodiment, optimization control of image brightness is executed with a larger passing area set on the optical axis L2 (S5). At least one of the light amount, exposure time, and gain is adjusted so that the histogram of the observation image acquired at any time approaches a predetermined target histogram. The target histogram may be defined by a target value, and for example, the width of the histogram (dispersion, half-width, standard deviation, etc.) may be predetermined as the target value. Although the details will be described later, in this embodiment, the photographed image is taken with the size of the passing area set to the first size, so the same size of the passing area is also used in image brightness optimization control. By doing this, a fundus image with the image brightness appropriately adjusted is captured as a photographed image.

After adjusting the image brightness, a process for setting the observation region is executed (S6). In this embodiment, the control unit 70 displays a grid on the observation image that divides the observation image into a plurality of regions (see FIG. 8). The examiner selects one of the plurality of areas divided by the grid via the input interface 75 (setting operation in this embodiment). The control unit 70 sets the part included in the selected area as the observed part. In the example of FIG. 8, the grid is divided into a lattice pattern, but the grid is not necessarily limited to this. For example, it may be divided in other ways such as concentric circles or spider webs. Furthermore, for example, by specifying an arbitrary point on the observed image, a predetermined range centered on that point may be set as the observed region.

Next, the control unit 70 arranges the smaller aperture of the two apertures corresponding to the photographing angle of view on the optical axis L2 (S7). Here, when the photographing angle of view is the first angle of view, the aperture 23b is positioned on the optical axis L2, and when the photographing angle of view is the second angle of view, the aperture 23d is positioned on the optical axis L2 by driving the motor 23e. .

After that, the control unit 70 executes focus control processing (S8). In the focus control process, within a predetermined adjustable range, the lens 14 is moved in one direction from the initial position in predetermined steps (for example, in the case of the first angle of view, 0.25D steps, and in the case of the second angle of view, 1 .0D steps). Furthermore, for each movement of a predetermined step, an evaluation value at the observation site set on the observation image is obtained, and the focus position is adjusted to a position where the evaluation value is at its peak. Information regarding a differential histogram at the observed site in the observed image may be used as the evaluation value. For more details, please refer to, for example, Japanese Patent Application Publication No. 2013-188316 by the present applicant.

In this embodiment, since the focus adjustment control (S8) is performed after the image brightness optimization control (S5) is completed, the imaging state can be detected better in the focus adjustment control (S8).

In this embodiment, focus adjustment is performed based on an observation image acquired with a smaller size passing region set on the optical axis L2. By setting the size of the passing area to a smaller size (that is, by narrowing it further), the depth of illumination becomes shallower than when shooting, which will be described later. As a result, the focus can be easily adjusted so that the observation site can be observed well. Furthermore, even if the observation site is undulating relative to the surroundings due to a disease or the like, the focus can be adjusted so that the observation site can be observed well.

After the focus adjustment, the control unit 70 returns the aperture arranged on the optical axis L2 to the larger aperture of the two apertures corresponding to the photographing angle of view (S9). After that, a fundus image is photographed (captured) (S10). At the time of photographing, the passing area is set to a larger size (that is, it becomes wider), so that a brighter photographed image is photographed. Further, as described above, as a result of the focus control processing, the focus is appropriately adjusted for the observed region in the photographed image, so that the observed region is likely to be observed well in the photographed image.

Note that when lens attachment 3 is attached (when the shooting angle is the second angle of view, which is larger), the NA is smaller than when it is not attached (when the shooting angle is the first angle of view), and the illumination The depth becomes deeper. In contrast, in this embodiment, when the lens attachment 3 is attached, the size of the passage area when adjusting the focus position becomes smaller than when the lens attachment 3 is not attached, so that the depth of illumination becomes deeper. things are suppressed. As a result, even when the lens attachment 3 is attached, the focused site on the fundus region can be easily confirmed through the observation image and the photographed image.

10 Irradiation optical system 11 Light emitting section irradiation optical system 23 Light restriction section 40 Focus adjustment section 70 Control section

Claims (4)

a light emitting section that emits observation light and photographing light;
an irradiation optical system that irradiates the fundus of the eye to be examined with light from the light emitting section, the irradiation optical system having a scanning means that scans the light on the fundus;
a light-receiving optical system having a light-receiving element that outputs a light-receiving signal by receiving the return light from the fundus;
a focus adjustment section that adjusts a focus position in at least one of the irradiation optical system and the light reception optical system;
a control means, as a fundus image based on the light reception signal from the light receiving element, an observation image based on the light reception signal of the return light from the observation light, and a photographed image based on the light reception signal of the return light from the photographing light. A fundus imaging device that obtains
an illumination depth adjustment unit capable of switching the illumination depth in at least one of the irradiation optical system and the light receiving optical system between a first illumination depth and a second illumination depth shallower than the first illumination depth; , further prepare,
The control means adjusts the focus position based on the observation image with the illumination depth set to the second illumination depth, and adjusts the focus position adjusted with the illumination depth set to the second illumination depth. A fundus photographing device, wherein the photographed image is photographed with the illumination depth set to the first illumination depth. The illumination depth adjustment section includes a light restriction section that is disposed at a position conjugate with the fundus in the light receiving optical system and that regulates a passage area through which the returned light guided to the light receiving element passes;
The light restriction section sets the size of the passage area to a first size corresponding to the first illumination depth and a second size that is narrower than the first size and corresponds to the second illumination depth. 2. The fundus photographing apparatus according to claim 1, wherein the fundus photographing apparatus is switchable between . The illumination depth adjustment unit adjusts the beam diameter of the light irradiated from the irradiation optical system to the subject's eye to a first beam diameter corresponding to the first illumination depth and a diameter smaller than the first beam diameter. 3. The fundus oculi photographing apparatus according to claim 1, further comprising a beam diameter switching unit that is thick and can be switched between a second beam diameter corresponding to the second illumination depth. The control means further executes a setting process for setting a part of the imaging range of the fundus as an observation region, and
The fundus photographing apparatus according to any one of claims 1 to 3, wherein the focus adjustment section is driven based on information regarding an imaging state at the observation site on the observation image.

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