JP7375322B2 - fundus imaging device - Google Patents

Description

The present disclosure relates to a fundus photographing device for obtaining a frontal image of the fundus.

Fundus photographing devices that photograph a frontal image of the fundus of an eye to be examined are widely used in the field of ophthalmology. Fundus imaging devices include fundus cameras, scanning laser ophthalmoscopes, and the following devices. For example, in Patent Document 1, a slit-shaped illumination light is scanned on the fundus of the eye, and an image of the illuminated slit-shaped area of the fundus is sequentially projected onto a two-dimensional imaging plane according to the scanning. An apparatus for obtaining frontal images is disclosed.

Special Publication No. 61-48940

When photographing a frontal image based on light reflected from the fundus, the thinner the slit-shaped area described above is, the less likely artifacts will occur on the frontal image. On the other hand, as the slit-shaped area becomes narrower, the efficiency of light transmission and reception decreases, making it difficult to obtain a bright frontal image.

The present disclosure has been made in view of at least one of the problems of the prior art, and its technical problem is to provide a fundus photographing device that can easily photograph bright and good fundus images.

A fundus imaging device according to a first aspect of the present disclosure includes an irradiation optical system that irradiates illumination light onto the fundus of an eye to be examined, and a light reception optical system that includes an image sensor that receives return light of the illumination light from the fundus. A fundus photographing device, comprising a photographing optical system, which acquires a fundus image, which is a frontal image of the fundus, based on a light reception signal from the image sensor , the photographing optical system comprising: a control means; an optical element for forming a region into a slit shape, a scanning section for scanning the imaging region with respect to the fundus, and a detection means for detecting information regarding the size of the pupil of the eye to be examined; The element is capable of switching the width of the imaging area to either a first width or a second width wider than the first width, and the control means is configured to switch the width of the imaging area to either a first width or a second width wider than the first width. a first imaging mode in which a first fundus image is acquired as a photographed image based on scanning of the photographing area of the second width; and a second photographing mode in which a second fundus image is acquired as a photographed image based on scanning of the photographing area of the second width. mode is selected based on the information regarding the size of the pupil.
A fundus imaging device according to a second aspect of the present disclosure includes an irradiation optical system that irradiates illumination light onto the fundus of an eye to be examined, and a light reception optical system that includes an image sensor that receives return light of the illumination light from the fundus. A fundus photographing device, comprising a photographing optical system, which acquires a fundus image, which is a frontal image of the fundus, based on a light reception signal from the image sensor , the photographing optical system comprising: a control means; an optical element for forming an area into a slit shape; and a scanning unit for scanning the imaging area with respect to the fundus; the optical element has a width of the imaging area that is a first width; a second width wider than the first width, and a rotating body in which a plurality of slit openings are arranged side by side on one circumference; an optical chopper having a first slit opening corresponding to a width of 1, and a second slit opening corresponding to a second width, the scanning unit including the rotating body, and driving the rotating body to rotate. The control means operates in a first imaging mode in which a first fundus image based on scanning the imaging area having the first width is acquired as a imaging image, and in scanning the imaging area having the second width. The photographing mode is switched between at least two modes: a second photographing mode in which a second fundus image based on the image is acquired as a photographed image;
A fundus imaging device according to a third aspect of the present disclosure includes: an irradiation optical system that irradiates the fundus of an eye to be examined with illumination light; and a light reception optical system that includes an image sensor that receives return light of the illumination light from the fundus. A fundus photographing device, comprising a photographing optical system, which acquires a fundus image, which is a frontal image of the fundus, based on a light reception signal from the image sensor , the photographing optical system comprising: a control means; comprising an optical element for forming a region into a slit shape, a scanning section for scanning the imaging region with respect to the fundus, and a diopter correction section for correcting a diopter error in the eye to be examined, The optical element can switch the width of the imaging area to either a first width or a second width wider than the first width, and the control means can switch the width of the imaging area to either a first width or a second width wider than the first width. a first photographing mode in which a first fundus image is obtained as a photographed image based on scanning the photographing region having a width of 2 photography mode, and the control means switches the photography mode between the first photography mode and the second photography mode according to the diopter correction amount in the diopter correction section. Selectively set one of them.

According to the present disclosure, it is easy to capture a bright and good fundus image.

1 is a diagram showing an external configuration of an apparatus according to one embodiment. FIG. 3 is a diagram showing an optical system housed in the photographing unit of the embodiment. FIG. 2 is a block diagram showing a control system of an apparatus according to an embodiment. 3 is a diagram showing an optical chopper that can be used as a scanning section in the optical system of FIG. 2. FIG. It is a diagram showing area division in an optical chopper. FIG. 3 is a timing chart for explaining light projection/reception control for each area. FIG. 3 is a flowchart showing the operation of the device. FIG. 7 is a diagram showing area division when acquiring observation images in a modified example. FIG. 6 is a diagram for explaining a switching operation between a normal photography mode and a small pupil photography mode.

"overview"
Hereinafter, embodiments of a fundus photographing apparatus according to the present disclosure will be described with reference to the drawings. The fundus photographing device photographs a fundus image. Note that in this disclosure, a front image of the fundus is referred to as a "fundus image."

The fundus photographing device (see FIG. 1) includes at least a photographing optical system (see, for example, FIG. 2) and a control section (see, for example, FIG. 3).

<Control unit>
The control section is a processing device (processor) that performs control processing for each section of the fundus photographing device and arithmetic processing. For example, the control unit is implemented by a CPU (Central Processing Unit), a memory, and the like. In this embodiment, the control section may also serve as an image processing section. The image processing unit executes at least one of generating a fundus image and performing various types of image processing on the fundus image.

<Photography optical system>
The photographing optical system includes an irradiation optical system and a light receiving optical system. The irradiation optical system irradiates the fundus of the eye to be examined with illumination light. The light receiving optical system includes at least an image sensor. Further, the light receiving optical system receives the return light of the illumination light from the fundus of the eye using the image sensor. The fundus photographing device acquires a fundus image, which is a frontal image of the fundus, based on a light reception signal from an image sensor.

The irradiation optical system and the light receiving optical system share at least an objective optical system (for example, an objective lens). In addition, the irradiation optical system and the light receiving optical system may share an optical path coupling part. The optical path coupling unit couples and separates the light projection optical path of the illumination light and the reception optical path of the fundus reflected light. In this case, the objective optical system is arranged on a common optical path of the light emitting optical path and the light receiving optical path formed by the optical path coupling section.

The image sensor receives return light from the illumination area. In this embodiment, the fundus reflected light with respect to the illumination light and the fluorescence from the fundus are collectively referred to as "return light." In this embodiment, the image sensor may be a two-dimensional light receiving element placed at a conjugate position of the fundus.

The image sensor may be, for example, a CMOS or a two-dimensional CCD. The image sensor receives return light from the illumination area. Signals from the image sensor are input to the image processing section. The image processing unit acquires (generates) a fundus image of the eye to be examined based on the signal from the image sensor.

In the following description, fundus images acquired by a fundus photographing device are broadly classified into photographed images and observation images. The photographed image is a fundus image photographed (captured) based on a release signal. A typical example of a photographed image is a still image. The observation image is a moving image used to observe the fundus when adjusting the imaging conditions of the device. For example, it is used when adjusting conditions such as focus and alignment. Furthermore, the observation image is acquired using infrared light.

In this embodiment, the photographing optical system is a scanning optical system. The photographing optical system includes an optical element and a scanning section.

The optical element is used to form a slit-shaped imaging area on the fundus of the eye. Moreover, the scanning unit scans the slit-shaped imaging area with respect to the fundus. For example, the imaging region may be scanned linearly on the fundus, or may be scanned rotationally on the fundus. In the case of rotational scanning, the rotation center may be the optical axis of the photographing optical system.

Additionally, the photographing optical system may include at least one of a light source and a barrier filter. The light source emits illumination light. The illumination light may be, for example, visible light or infrared light. Further, a plurality of light sources may be provided for each wavelength.

<Optical element>
The optical element is disposed on at least one of the optical paths of the illumination light and the return light, thereby forming a slit-shaped imaging region on the fundus of the eye. The optical element may have, for example, a slit opening arranged at a position conjugate with the fundus of the eye. Note that the optical element is preferably arranged in each of the optical path of the illumination light (that is, the optical path of the irradiation optical system) and the optical path of the return light (that is, the optical path of the light receiving optical system). By disposing optical elements in each of the optical path of the illumination light and the optical path of the return light, stray light that causes artifacts is less likely to be imaged.

Note that in the present disclosure, "conjugate" is not necessarily limited to a perfect conjugate relationship, but includes "substantially conjugate". That is, the term "conjugate" in the present disclosure also includes a case where the arrangement is shifted from a perfect conjugate position within the allowable range in relation to the technical significance of each part.

In this embodiment, the width of the imaging area can be switched to either a first width or a second width wider than the first width by the optical element. In this case, the optical element may have at least two types of slit openings: a first slit opening corresponding to the first width and a second slit opening corresponding to the second width.

However, it is not necessarily limited to this. For example, the optical element may have a slit aperture with variable width.

Furthermore, the imaging area may be further switchable to three or more widths. For example, the width of the imaging area may be switchable to a third width that is different from both the first width and the second width.

Note that in the present disclosure, "width" means "the length from one end of a vertically long object to the other end." In other words, it is the length from end to end in the transverse direction.

Note that the optical element disposed on the optical path of the returned light may also be used by the image sensor. In this case, the image sensor may be a line sensor formed in the shape of a slit. Further, a CMOS in which line exposure is performed on a two-dimensional imaging surface (in other words, has a rolling shutter function) may be used.

<Scanning section>
The scanning unit scans the fundus of the eye with a slit-shaped imaging area.

<First scanning method: method of driving the slit forming section>
The optical element may be part of the scanning section. In this case, the optical element may be driven to scan a slit-shaped imaging area on the fundus.

A specific example of the scanning unit is an optical chopper (see, for example, FIG. 4). In an optical chopper, the optical element is a rotating body in which a plurality of slit openings are arranged side by side on one circumference. In an optical chopper, a rotating body is rotationally driven. Thereby, a plurality of slit openings are successively traversed with respect to the optical path of the illumination light or return light. The shape of the rotating body may be, for example, a disk shape or a cylindrical shape. In a cylindrical rotating body, a plurality of slits are formed on the cylindrical side surface. Note that the rotating body may be driven at a constant speed.

Furthermore, one rotating body may serve as both an optical element disposed on the optical path of illumination light and an optical element disposed on the optical path of return light. In this case, the optical elements can be driven in good synchronization on each of the optical path of the illumination light and the optical path of the return light.

The rotating body has a first area in which one or more first slit openings corresponding to a first width are arranged in succession, and one or two second slit openings corresponding to a second width. and a second area arranged in succession (for example, see FIG. 5). In this case, the control unit switches the width of the imaging region on the fundus between a first period in which the first area passes through the optical path and a second period in which the second area passes through the optical path.

When the scanning unit is an optical chopper, it may include a sensor that detects the rotational position of the rotating body.

Further, the optical element placed on the optical path of the illumination light and the optical element placed on the optical path of the return light may be separate bodies. When a CMOS is used as the image sensor, the CMOS may also serve as an optical element disposed on the optical path of the returned light. That is, the line exposure using the rolling shutter function described above may be controlled in synchronization with the displacement of the optical element on the illumination light side. Thereby, the number of parts of the optical system can be reduced.

<Second scan method: method for driving the deflection device>
The scanning unit may be separate from the optical element. For example, the scanning unit may be a device that deflects the traveling direction of light (hereinafter referred to as a "deflection device"). The deflection device deflects the illumination light and the return light in a direction according to the control signal. The deflection device may be any one of various devices such as a galvanometer mirror, MEMS, and an AOD (Acousto-Optic Deflector). Preferably, the deflection device is placed at a position conjugate with the anterior segment of the eye to be examined.

Note that in this method, the return light from the fundus is descanned by the deflection device, so that there is no need to move the optical element placed on the optical path of the return light in conjunction with the scan. Thus, for example, the optical element may have a slit opening fixedly arranged at the fundus conjugate position.

As described above, the scanning method in this embodiment can be broadly classified into at least two methods: "a method for driving the slit forming section" and "a method for driving a deflection device."

<Switching shooting mode>
The control unit switches the photographing mode of the device between a first photographing mode and a second photographing mode. Here, in the first photographing mode, the control unit photographs the first fundus image by scanning the photographing region with the first width. In the second photographing mode, the control unit photographs a second fundus image by scanning the photographing region with a second width. Thereby, a fundus image can be photographed by changing the amount of emitted and received light. In the first photographing mode, the photographing area is narrower than in the second photographing mode, so that artifacts due to reflections from the objective lens and the like are less likely to occur. On the other hand, in the second photographing mode, the photographing area is wider than in the first photographing mode, so that the efficiency of light projection and reception with respect to the amount of light is improved.

When the scanning unit is an optical chopper equipped with a rotating body divided into a first area and a second area as described above, photographing in each mode is performed as follows.

In this case, in the first imaging mode, the control unit photographs the first fundus image based on the signal from the image sensor exposed during the first period in which the first area passes through the optical path. Furthermore, in the second photographing mode, a second fundus image is acquired based on a signal from an image sensor exposed during a second period in which the second area passes through the optical path.

<Observation image acquisition operation when using an optical chopper>
In this case, the control unit may control the optical chopper to continuously rotate the rotating body and acquire observation images at a constant frame rate based on the signal from the image sensor.

In this case, the control unit may acquire the first observation image and the second observation image alternately every time the first period and the second period switch. Here, the first observation image is generated based on the signal from the image sensor exposed in the first period. Further, the second observation image is generated based on the signal from the image sensor exposed in the second period. At this time, the control unit may reduce either the amount of illumination light or the gain of the light reception signal from the image sensor in the second period compared to the first period (see FIG. 6). Thereby, the brightness is made uniform between the first observed image and the second observed image. Therefore, when the first observed image and the second observed image are displayed as a moving image, screen flickering is suppressed.

Instead of this, the control unit acquires each frame of the observation image based on a signal from an image sensor exposed during both at least part of the first period and at least part of the second period. (For example, see FIG. 8). Thereby, when generating each frame, the amount of light with which the image sensor is exposed is likely to be made uniform. As a result, it becomes easier to obtain an observation image with uniform brightness.

Further, the control unit may acquire the observation image by exposing the image sensor in only one of the first period and the second period. Although the frame rate is slower than the above method, it is useful for displaying observation images with uniform brightness.

<First aspect of mode switching>
For example, the first imaging mode may be set to capture a color image of the fundus as the first fundus image. Further, the second photographing mode may be set to photograph a fluorescence image of the fundus as the second fundus image. In this case, the control unit changes the width of the imaging area used for imaging the fundus image according to the imaging mode, and changes at least the wavelength of the illumination light according to the imaging mode. For example, by controlling the light source according to the photographing mode, the control unit causes the light source to emit visible light such as white light in the first photographing mode, and emits excitation light according to the fluorescent substance in the second photographing mode. It may also be irradiated. Furthermore, in the second photographing mode, the control section may further insert a barrier filter on the optical path of the returned light. The barrier filter has spectral characteristics that block light reflected from the fundus and allow fluorescence from the fundus to pass toward the image sensor. Since reflections from the objective lens and the like are also blocked by the barrier filter, artifacts are less likely to occur in the fluorescence image of the fundus.

In this way, when photographing a color image of the fundus, the width of the photographing region on the fundus becomes relatively narrow, thereby suppressing artifacts caused by reflections from the objective lens and the like. In addition, when taking a fluorescence image of the fundus, the width of the imaging area on the fundus is relatively wide, which allows for efficient emitting and receiving of excitation light and fluorescence, making it easier to obtain a fluorescence image with high brightness. Become.

<Second mode switching mode>
Incidentally, in order to reduce flare, the exit pupil and the entrance pupil are separated in the photographing optical system. In this embodiment, the distance between the exit pupil and the entrance pupil may be changeable. If the distance between the exit pupil and the entrance pupil is made closer, even an eye to be examined with a smaller pupil can be photographed. On the other hand, by making the distance between the exit pupil and the entrance pupil closer, artifacts due to reflections on the objective lens are more likely to occur.

Therefore, for example, the control unit may selectively set either the first imaging mode or the second imaging mode depending on the pupil diameter of the eye to be examined. The first photographing mode may be set when photographing a subject's eye with a smaller pupil diameter. Further, the second photographing mode may be set when photographing a subject's eye with a larger pupil diameter.

Furthermore, in the first shooting mode, compared to the second shooting mode, the control unit not only narrows the width of the shooting area as described above, but also controls the shooting optical system (more specifically, the irradiation optical system ), the distance between the exit pupil and the entrance pupil may be brought closer. According to this, even an eye to be examined with a small pupil can be photographed satisfactorily while suppressing the occurrence of artifacts.

In this case, the fundus photographing device may include a pupil information acquisition unit that is information regarding the size of the pupil of the eye to be examined. The information regarding the pupil size may be the pupil diameter or information correlated with the pupil diameter. The pupil information acquisition unit may include, for example, an anterior segment observation optical system that photographs the anterior segment of the subject's eye. For example, the control unit compares the size of the pupil detected from the image of the anterior segment obtained through the anterior segment observation optical system with a threshold value, and selects the imaging mode according to the comparison result. Good too. Further, the pupil information acquisition unit may acquire information regarding the size of the pupil of the eye to be examined measured by another ophthalmologic apparatus. Furthermore, information regarding the pupil size may be input to the examiner via the operation unit.

<Third mode switching mode>
The photographing optical system may include a diopter correction section for correcting a diopter error in the eye to be examined. The diopter correction unit may be arranged, for example, on a common optical path of the irradiation optical system and the light receiving optical system, or may be arranged on each of the independent optical paths of the irradiation optical system and the light receiving optical system.

The occurrence of artifacts due to reflection on the objective lens changes depending on the state of diopter correction. The fundus conjugate plane formed closest to the objective lens is displaced according to the amount of diopter correction. For example, the closer the fundus conjugate plane is to the lens surface of the objective lens, the more likely artifacts will occur. On the other hand, within a certain diopter correction amount range, artifacts may not be a problem. However, this range is considered to differ depending on the optical system.

Therefore, the control unit may selectively set either the first photography mode or the second photography mode depending on the diopter correction amount in the diopter correction unit. The control unit selects the first shooting mode in a first range of the first diopter correction amount where artifacts are likely to occur, and selects the second shooting mode in a second range where artifacts are less likely to occur compared to the first range. You may choose.

"Example"
Next, an example will be described with reference to FIGS. 1 to 7.

A fundus photographing device 1 (hereinafter simply referred to as "photographing device 1") according to an embodiment forms illumination light into a slit shape on the fundus of an eye to be examined, and a region formed in the slit shape on the fundus. By scanning and receiving the fundus reflected light of the illumination light, a front image of the fundus is captured.

<Appearance of the device>
The external configuration of the photographing device 1 will be described with reference to FIG. 1. The photographing device 1 includes a photographing unit 3. The photographing unit 3 mainly includes an optical system shown in FIG. The photographing device 1 includes a base 7, a drive unit 8, a face support unit 9, and a face photographing camera 110, and uses these to adjust the positional relationship between the eye E and the photographing unit 3.

The drive unit 8 can move in the left-right direction (X direction) and the front-back direction (Z direction, in other words, the working distance direction) with respect to the base 7. Further, the drive unit 8 further moves the photographing unit 3 on the drive unit 8 in a three-dimensional direction with respect to the eye E to be examined. The drive unit 8 includes an actuator for moving the drive unit 8 or the photographing unit 3 in each predetermined movable direction, and is driven based on a control signal from the control unit 80. The face support unit 9 supports the subject's face. The face support unit 9 is fixed to the base 7.

The face photographing camera 110 is fixed to the housing 6 so that the positional relationship with respect to the photographing unit 3 is constant. The face photographing camera 110 photographs the subject's face. The control unit 100 identifies the position of the eye E to be examined from the photographed facial image, and controls the driving unit 8 to align the imaging unit 3 with the identified position of the eye E to be examined. Note that the detailed configuration of the control system will be described later with reference to FIG.

Further, the photographing device 1 further includes a monitor 120. The monitor 120 displays a fundus observation image, a fundus photography image, an anterior segment observation image, and the like.

<Optical system of example>
The optical system of the photographing device 1 will be explained with reference to FIG. The photographing device 1 includes a photographing optical system (fundus photographing optical system) 10 and an anterior segment observation optical system 40. These optical systems are provided in the photographing unit 3.

In FIG. 2, positions conjugate to the pupil of the subject's eye are indicated with a ``△'' on the photographing optical axis, and positions conjugate to the fundus are indicated with an ``x'' on the photographing optical axis, respectively.

The photographing optical system 10 includes an irradiation optical system 10a and a light receiving optical system 10b. In the embodiment, the irradiation optical system 10a includes a light source unit 11, a lens 13, a slit-like member 15a, lenses 17a, 17, a mirror 18, a perforated mirror 20, and an objective lens 22. The light receiving optical system 10b includes an objective lens 22, a perforated mirror 20, lenses 25a and 25b, a slit-like member 15b, and an image sensor 28. Note that the perforated mirror 20 is an optical path coupling portion that couples the optical paths of the irradiation optical system 10a and the light receiving optical system 10b. The perforated mirror 20 reflects the illumination light from the light source toward the subject's eye E, and allows a portion of the fundus reflected light from the subject's eye E to pass through the aperture toward the imaging device. Various beam splitters other than the apertured mirror 20 can be used. For example, instead of the perforated mirror 20, a mirror in which the perforated mirror 20, the transparent part, and the reflective part are reversed may be used as the optical path coupling part. However, in this case, the independent optical path of the light receiving optical system 10b is placed on the reflection side of the mirror, and the independent optical path of the irradiation optical system 10a is placed on the transmission side of the mirror. Furthermore, the hole-opening mirror and the mirror as an alternative thereof can each be further replaced with a combination of a half mirror and a light shielding part.

In this embodiment, the light source unit 11 includes multiple types of light sources with different wavelength bands. For example, the light source unit 11 includes visible light sources 11a and 11b and infrared light sources 11c and 11d. The two light sources having the same wavelength range are placed apart from the imaging optical axis L on the pupil conjugate plane. The two light sources are arranged along the X direction, which is the scanning direction in FIG. 2, and are arranged axially symmetrically with respect to the photographing optical axis L. As shown in FIG. 2, the outer peripheral shapes of the two light sources may be rectangular shapes that are longer in the direction intersecting the scanning direction than in the scanning direction.

Note that in FIG. 2, two visible light sources indicated by reference numerals 11a and 11b are shown, but each light source 11a and 11b includes a plurality of visible light sources for each wavelength. For example, the visible light sources 11a and 11b may include light sources corresponding to three colors, R (red), G (green), and B (blue), respectively. Accordingly, in this embodiment, any one of the three colors R (red), G (green), and B (blue) can be irradiated in any combination. For example, when photographing a color fundus image, three colors of R (red), G (green), and B (blue) may be irradiated. Furthermore, when performing autofluorescence photography, which is a type of fluorescence photography, light having a wavelength of G (green) or B (blue) may be irradiated.

Light from the light source passes through the lens 13 and is irradiated onto the slit-shaped member 15 . In the present embodiment, the slit-like member 15a has a light-transmitting portion (opening) that is elongated along the Y direction. As a result, the illumination light is formed in a slit shape on the fundus conjugate plane (the region illuminated in a slit shape on the fundus is illustrated as B).

In FIG. 2, the slit-shaped member 15a is displaced by the drive unit 15c so that the transparent part crosses the photographing optical axis L in the X direction. Thereby, scanning of the illumination light in this embodiment is realized. Note that in this embodiment, scanning by the slit-shaped member 15b is also performed on the light receiving system side. In this embodiment, the slit-like members on the light emitting side and the light receiving side are driven in conjunction with each other by one driving section (driver).

In the irradiation optical system 10a, the images of each light source are relayed by the optical system from the lens 13 to the objective lens 22, and are imaged on the pupil conjugate plane. That is, on the pupil conjugate plane, images of the two light sources are formed at positions separated in the scanning direction. In this manner, in this embodiment, the two light projection areas P1 and P2 (exit pupils in this embodiment) on the pupil conjugate plane are formed as images of two light sources.

Further, the slit-shaped light that has passed through the slit-shaped member 15a is relayed by the optical system from the lens 17a to the objective lens 22, and is imaged on the fundus Er. Thereby, the illumination light is formed into a slit shape on the fundus Er. The illumination light is reflected on the fundus Er and taken out from the pupil Ep.

Here, since the aperture of the perforated mirror 20 is conjugate with the pupil of the subject's eye, the fundus reflected light used for photographing the fundus image passes through the image of the perforated mirror aperture (pupil image) on the pupil of the subject's eye. Limited to some. In this way, the image of the aperture on the pupil of the subject's eye becomes the light-receiving region R in this example (the entrance pupil in this example). The light receiving area R is formed between two light projecting areas P1 and P2. In addition, as a result of appropriately setting the imaging magnification of each image, the diameter of the aperture, and the arrangement interval of the two light sources, the light receiving area R and the two light emitting areas P1 and P2 do not overlap each other on the pupil. is formed. In other words, the exit pupil and the entrance pupil are separated. As a result, the occurrence of flare is effectively reduced.

The fundus reflected light that has passed through the objective lens 22 and the aperture of the perforated mirror 20 forms an image of a slit-shaped region of the fundus Er at a conjugate position of the fundus via lenses 25a and 25b. At this time, harmful light is removed by disposing the light-transmitting portion of the slit-like member 15b at the image formation position.

The image sensor 28 is placed at a position conjugate to the fundus. In this embodiment, a relay system 27 is provided between the slit-like member 15b and the image sensor 28, so that both the slit-like member 15b and the image sensor 28 are arranged at conjugate positions of the fundus. As a result, both the removal of harmful light and the imaging are performed satisfactorily. Alternatively, the relay system 27 between the image sensor 28 and the slit-shaped member 15b may be omitted, and the two may be arranged close to each other. In this embodiment, a device having a two-dimensional light-receiving surface is used as the image sensor 28. For example, CMOS, two-dimensional CCD, etc. may be used. An image of the slit-shaped region of the fundus Er, which is imaged by the transparent portion of the slit-shaped member 15b, is projected onto the image sensor 28. The image sensor 28 is sensitive to both infrared light and visible light.

In this embodiment, as the slit-shaped illumination light scans the fundus Er, an image (slit-shaped image) of the scanning position on the fundus Er is sequentially projected for each scanning line of the image sensor 28. In this way, the entire image of the scanning range is projected onto the image sensor in a time-division manner. As a result, a front image of the fundus Er is captured as the entire scanning range.

In addition, although the scanning unit in the light receiving system in the embodiment is a device that mechanically scans the slit, it is not necessarily limited to this. For example, the scanning section on the light receiving optical system side may be a device that electronically scans the slit. As an example, when the image sensor 28 is a CMOS, scanning of the slit may be realized by a rolling shutter function of the CMOS. In this case, by displacing the exposed area on the imaging surface in synchronization with the scanning section in the light projection system, it is possible to efficiently image while removing harmful light. Further, a liquid crystal shutter or the like can also be used as a scanning unit that electronically scans the slit.

The photographing optical system 10 has a diopter correction section. In this embodiment, diopter correction sections (diopter correction optical systems 17 and 25) are provided in each of the independent optical path of the irradiation optical system 10a and the independent optical path of the light receiving optical system 10b. Hereinafter, for convenience, the irradiation side diopter correction optical system will be referred to as the irradiation side diopter correction optical system 17, and the light receiving side diopter correction optical system will be referred to as the light receiving side diopter correction optical system 25. The irradiation side diopter correction optical system 17 of this embodiment includes a lens 17a, a lens 17b, and a drive section 17c (see FIG. 3). Further, the light-receiving side diopter correction optical system 25 of this embodiment includes a lens 25a, a lens 25b, and a drive section 25c (see FIG. 3). In the irradiation side diopter correction optical system 17, the distance between the lenses 17a and 17b is changed, and in the light receiving side diopter correction optical system 25, the distance between the lenses 25a and 25b is changed. Thereby, diopter correction is performed in each of the irradiation optical system 10a and the light receiving optical system 10b.

<Split index projection optical system>
As shown in FIG. 2, the photographing optical system 10 further includes a split index projection optical system 50 as an example of a focus index projection optical system. The split index projection optical system 50 projects two split indexes onto the fundus of the eye. The split index is used to detect the focus state. Further, in this embodiment, the refractive power of the eye E to be examined is acquired from the detection result of the focus state.

The split index projection optical system 50 may include at least a light source 51 (infrared light source), an index plate 52, and a deflection prism 53, for example. In this embodiment, the index plate 52 is arranged at a position corresponding to the imaging surface of the light receiving optical system 50. Similarly, each of the slit-shaped members 15a and 15b are also arranged at corresponding positions. Specifically, when the diopter correction amounts on the irradiation side and the light receiving side are 0D, the optotype plate 52 is placed at a position that is substantially conjugate with the fundus of the emmetropic eye (0D eye). The deflection prism 53 is disposed closer to the index plate 52 on the eye to be examined side than the index plate 52 is.

The indicator plate 52 is formed using, for example, slit light as an indicator. The deflection prism 53 separates the index light beam that has passed through the optotype plate 52 to form a split index. The separated split index is projected onto the fundus of the subject's eye via the irradiation side diopter correction optical system 17 to the objective lens 22. Therefore, the split index is reflected in the fundus image (eg, fundus observation image).

When the index board 52 is deviated from the fundus conjugate position, the two split indices are separated on the fundus, and when the index board 52 is placed at the fundus conjugate position, the two split indices are matched. The conjugate relationship is adjusted by the irradiation-side diopter correction optical system 17 disposed between the deflection prism 53 and the eye to be examined Er. Therefore, in this embodiment, defocusing is performed while making the irradiation side diopter correction amount and the light receiving side diopter correction amount match. At this time, the separated state of the split index indicates the focused state. By adjusting the diopter correction amounts on the irradiation side and the light receiving side so that the two split indicators match, the imaging surface and each of the slit-like members 15a and 15b are in a conjugate positional relationship with the fundus. becomes.

<Detailed explanation of optical chopper>
The scanning unit may be, for example, an optical chopper 150 as shown in FIG. The optical chopper 150 has a wheel 151 having a plurality of slit openings formed on its outer periphery, and can scan the slits at high speed by rotating the wheel 151. The wheel 151 is an example of a disc-shaped rotating body.

In this case, the wheel 151 corresponds to the slit-like members 15a and 15b shown in FIG. 2, and the main body portion 152 includes a drive portion 15c (see FIG. 3).

In this embodiment, the photographing device 1 may include a sensor (not shown) that detects the amount of rotation of the wheel 151. Thereby, the control unit 100 can detect the rotational position of the wheel 151.

Here, in FIG. 2, from the light source unit 11 to the mirror 18 of the irradiation optical system 10a and from the perforated mirror 20 to the image sensor 28 of the light receiving optical system 10b are arranged in parallel in the X direction. By rotating the orientations of the mirror 20 and the mirror 18 by 90 degrees from the illustrated state and arranging them in parallel in the Y direction, the optical chopper can be used as a scanning section. In this case, by making the optical axis of the irradiation optical system 10a and the optical axis of the light receiving optical system 10b cross each other at the upper and lower ends of the wheel 151, a single optical chopper 150 can be used to Scanning of the light receiving system can be easily synchronized.

As shown in FIG. 5, the wheel 151 of this embodiment is divided into four areas: two first areas and two second areas. Four slit openings are evenly arranged in each area.

A first slit opening corresponding to an imaging area having a first width is arranged in the first area. Further, in the second area, a second slit opening corresponding to the imaging area of the second width is arranged. In order to make the second width wider than the first width, the second slit opening is formed wider than the first slit opening.

The two first areas are arranged diagonally on the wheel 151 (symmetrical with respect to the rotation axis), and the two second areas are also arranged diagonally on the wheel 151. As a result, slit openings having the same width are always arranged at diagonal positions on the wheel 151. In this embodiment, the optical axis of the irradiation optical system 10a and the optical axis of the light receiving optical system 10b intersect at two diagonal locations on the wheel 151. Thereby, the relationship between the width of the slit opening that crosses the optical path of the irradiation optical system 10a and the width of the slit opening that crosses the optical path of the light receiving optical system 10b can be kept constant.

By using such an optical chopper 150, in this embodiment, imaging on the fundus is performed between the first period in which the first area passes through the optical path and the second period in which the second area passes through the optical path. The width of the region switches between a first width and a second width.

As an example, in this embodiment, one frame of fundus image is acquired for each area. That is, during one rotation of the wheel 151, a maximum of four frames of fundus images are acquired. Specifically, the four slit openings arranged in one area cross the optical path, so that the returned light scans the image sensor 28 four times. During this time, the image sensor 28 is continuously exposed to light, and one frame of the fundus image is formed based on the signals accumulated during that time. However, the present invention is not necessarily limited to this, and one frame of the fundus image may be acquired every time an arbitrary number of slit openings cross.

<Barrier filter>
Returning to FIG. 2, the explanation of the optical system will be continued. The photographing device 1 further includes a barrier filter 61. During fluorescence photography, the light-receiving optical system 10b guides fluorescence from the fundus of the eye based on excitation light to the image sensor 28. The barrier filter 61 may be placed on an independent optical path of the light receiving optical system. The barrier filter 61 has spectral characteristics that block light in the same wavelength range as the excitation light and allow fluorescence to pass. As an example, in this embodiment, the barrier filter 61 has spectral characteristics suitable for autofluorescence photography. For example, green or blue light, which is excitation light, is blocked, and light with a longer wavelength is allowed to pass to the image sensor 28 side. Thereby, the autofluorescence is selectively received by the image sensor 28. As a result, an excellent autofluorescence image of the fundus can be obtained. The photographing device 1 may include a drive unit 61a that inserts and removes the barrier filter 61. Furthermore, the insertion and removal of the barrier filter is controlled by, for example, the control unit 100.

<Anterior segment observation optical system>
Next, the anterior segment observation optical system 40 will be explained. The anterior segment observation optical system 40 shares the objective lens 22 and the dichroic mirror 43 with the photographing optical system 10. The anterior segment observation optical system 40 further includes a light source 41, a half mirror 45, an image sensor 47, and the like. The image sensor 47 is a two-dimensional image sensor, and is arranged, for example, at a position optically conjugate with the pupil Ep. The anterior segment observation optical system 40 illuminates the anterior segment with infrared light and captures a frontal image of the anterior segment.

Note that the anterior eye segment observation optical system 40 shown in FIG. 2 is only an example, and the anterior eye segment may be imaged using an optical path independent from other optical systems.

<Control system of example>
Next, the control system of the photographing device 1 will be explained with reference to FIG. In this embodiment, the control section 100 controls each section of the photographing device 1. Further, for convenience, it is assumed that image processing of various images obtained by the photographing device 1 is also performed by the control unit 100. In other words, in this embodiment, the control section 100 also serves as an image processing section.

The control unit 100 is a processing device (processor) having an electronic circuit that performs control processing of each unit and arithmetic processing. The control unit 100 is implemented by a CPU (Central Processing Unit), a memory, and the like. The control unit 100 is electrically connected to the storage unit 101 via a bus or the like.

The storage unit 101 stores various control programs, fixed data, and the like. Further, temporary data and the like may be stored in the storage unit 101.

Images captured by the imaging device 1 may be stored in the storage unit 101. However, the present invention is not necessarily limited to this, and the captured image may be stored in an external storage device (for example, a storage device connected to the control unit 100 via LAN and WAN).

Further, the control section 100 is electrically connected to each section such as the drive section 8, the light sources 11a to 11d, the image sensor 28, the light source 41, the image sensor 47, the light source 51, the input interface 110, and the monitor 120.

Further, the control unit 100 controls each of the above members based on an operation signal output from the input interface 110 (operation input unit). The input interface 110 is an operation input section that receives operations from the examiner. For example, it may be a mouse, a keyboard, etc.

<Operation explanation>
Next, the photographing operation will be explained with reference to the flowchart in FIG.

<Alignment>
The photographing device 1 may automatically start the photographing operation when the subject's face is placed relative to the face support section 9 and included in the photographing range of the face detection camera 110.

First, the face detection camera 110 and the anterior eye segment observation optical system 40 begin to take images in parallel, and alignment adjustment is performed using the results of both images.

Specifically, the control unit 100 detects the position of one of the left and right eyes included in the face image, and drives the drive unit 8 based on the position information. Thereby, the position of the photographing unit 4 is adjusted to a position where anterior segment observation is possible.

Next, an alignment reference position is set based on the anterior segment front image, and alignment is guided to the set alignment reference position. In this embodiment, the positional relationship between the eye E to be examined and the photographing unit 3 is adjusted by the control unit 100 based on the anterior segment front image. In this embodiment, the control unit 100 determines the position at which the center of the pupil in the anterior eye segment observation image and the image center (in this embodiment, the position of the imaging optical axis L) substantially coincides, based on the signal from the image sensor 47. A first reference position is established that targets the relationship. Then, an alignment shift from the first reference position is detected, and the photographing unit 4 is moved vertically and horizontally in a direction in which the alignment shift is eliminated. At this time, the alignment deviation with the first reference position may be detected, for example, based on the amount of deviation between the pupil center and the imaging optical axis on the anterior segment observation image. Furthermore, if the fundus imaging device 1 includes, for example, an alignment projection optical system that projects an alignment index onto the corneal vertex, an alignment shift may be detected based on the amount of shift between the alignment index and the imaging optical axis. .

Further, the control unit 100 moves the photographing unit 4 in the front-back direction so that the anterior segment observation image is focused on the pupil Ep. Thereby, the distance from the device to the eye to be examined is adjusted to a predetermined working distance.

As described above, in this embodiment, as a result of the alignment adjustment, the positional relationship between the eye to be examined and the photographing unit 4 is such that the center of the light receiving area R on the pupil of the eye to be examined (that is, the photographing optical axis) coincides with the center of the pupil. (the first reference position in this embodiment).

<Acquisition and display of fundus observation images>
Subsequently, the control unit 100 starts acquiring and displaying a fundus observation image. Specifically, the control unit 100 turns on the light sources 11c and 11d simultaneously, and starts driving the drive unit 15c, so that the slit-shaped illumination light repeatedly scans a predetermined range on the fundus Er.

Each time each area in the wheel 151 passes through the optical path, one frame of the fundus image is generated as a fundus observation image based on the signal output from the image sensor 28. The control unit 100 causes the fundus observation image to be displayed on the monitor 120 as a substantially real-time moving image.

At this time, the efficiency of light transmission and reception differs greatly between when the first area passes through the optical path and when the second area passes through the optical path. Therefore, the control unit 100 switches at least one of the light intensity of the light sources 11c and 11d and the gain of the light reception signal according to the rotational position of the wheel 151 detected by the sensor. Specifically, when the first area passes through the optical path (first period in this example), the light source 11c, Either the amount of light of 11d or the gain of the received light signal is increased (see FIG. 6). In this manner, in this embodiment, an observation image is obtained each time each area passes through the optical path, so the observation image can be displayed at a higher frame rate.

Note that when LEDs are used as the light sources 11c and 11d, the time response to the control signal is quick, so it is preferable that the control unit 100 performs the above control by controlling the light sources 11c and 11d.

<Diopter correction>
Next, the focus states of the irradiation optical system and the light reception optical system are adjusted based on the fundus observation image. In this embodiment, after alignment is completed, focus adjustment is performed by driving the diopter correction optical system. At this time, in this embodiment, both the irradiation side diopter correction optical system 17 and the light receiving side diopter correction optical system 25 are driven.

In the focus adjustment process, the control unit 100 first turns on the light source 51 to start projecting the split index onto the fundus. The control unit 100 performs defocusing by changing the correction amount while making the irradiation side diopter correction amount match the light receiving side diopter correction amount. In addition, the control unit 100 detects the separation state of the split index from the fundus observation image every time the correction amount changes, and adjusts the irradiation side diopter correction amount and the receiving side diopter correction amount until the split index matches. adjust. As a result of such adjustment, the imaging surface and each of the slit-like members 15a and 15b have a conjugate positional relationship with the fundus.

Here, during the focus adjustment process, the control unit 100 may switch the light amount of the light source 51 between when the first area passes through the optical path and when the second area passes through the optical path. (See Figure 6). For example, when the first area passes through the optical path, the amount of light from the light source 51 may be increased compared to when the second area passes through the optical path. This makes it easy to detect the separation state of the split index even if, for example, the brightness of the observed image varies from frame to frame.

<Selecting shooting mode and shooting>
Next, the control unit 100 selects a shooting mode and adjusts shooting conditions according to the shooting mode. The imaging mode is selected, for example, according to an instruction from the examiner. The control unit 100 may select the imaging mode between the normal imaging mode and the fluorescence imaging mode. The normal photographing mode is set to photograph a fundus image based on fundus reflected light. The fluorescence photography mode is set to capture a fluorescence fundus image.

In this embodiment, the control unit 100 adjusts at least the wavelength-related conditions of the light emitted from the light sources 11a and 11b according to the shooting mode, and also controls the insertion and removal of the barrier filter 61 into and out of the optical path of the light receiving optical system 10b. Adjust conditions. Furthermore, in this embodiment, the control unit 100 also adjusts the conditions regarding the exposure period of the image sensor 28 when acquiring the fundus image.

Specifically, in the normal photography mode, photography is performed by simultaneously emitting three colors, R (red), G (green), and B (blue) from the light sources 11a and 11b. Furthermore, the barrier filter 61 is retracted from the optical path of the light receiving optical system 10b. Further, a fundus image is generated based on the exposure of the image sensor 28 while the first area passes through the optical path. By setting the width of the slit-shaped photographing region on the fundus to be relatively narrow, it is possible to photograph a photographed image in which artifacts caused by reflections from the objective lens 22 and the like are suppressed.

Furthermore, in the fluorescence photography mode of this embodiment, photography is performed by emitting one color of B (blue) from the light sources 11a and 11b. Further, a barrier filter 61 is inserted into the optical path of the light receiving optical system 10b. As a result of inserting the barrier filter 61, there is no need to consider the above-mentioned artifacts. Therefore, a fundus image is generated based on the exposure of the image sensor 28 while the second area passes through the optical path. In other words, photography is performed with the width of the slit-shaped photography area wider than in the normal photography mode.

Note that during photographing, the control unit 100 may stop light emission from the observation light sources 11c and 11d, and then turn on the photographing light sources 11a and 11b. In this case, a photographed image of the fundus is obtained as a result of photographing based on visible light emitted from the light sources 11a and 11b.

<Transformation example>
Although the description has been made above based on the embodiments, the content of the embodiments can be changed as appropriate when implementing the present disclosure.

<Small pupil photography mode>
For example, in the above embodiment, the photographing mode is selected between the normal photographing mode and the fluorescence photographing mode, but the present invention is not necessarily limited to this. For example, the photographing mode may be switched between a normal photographing mode and a small pupil photographing mode. In both the normal photography mode and the small pupil photography mode, a photographed image is acquired based on the light reflected from the fundus.

In this case, the imaging device 1 may acquire the pupil diameter from the anterior segment observation image as information regarding the pupil size of the eye to be examined. The control unit 100 compares the pupil diameter of the eye to be examined with a predetermined threshold. As an example, a value of approximately φ4 mm may be used as the threshold value. When the pupil diameter of the eye E to be examined is larger than the threshold value, the normal photography mode is set. Further, when the pupil diameter is smaller than the threshold value, the small pupil imaging mode is set.

In this case, the distance between each of the light sources 11a to 11d and the optical axis L may be changeable. By changing the distance between each of the light sources 11a to 11d and the optical axis L, the clearance between the entrance pupil and the exit pupil may be changeable. The larger the clearance, the less likely artifacts will occur due to the objective lens 22. If the clearance is small, it will be advantageous for photographing eyes with small pupils.

In this case, for example, when forming an exit pupil on the pupil of the eye to be examined by placing a light source at a position away from the photographing optical axis on the pupil conjugate plane, a set of two light sources is shown in FIG. As shown, two sets may be arranged. The two sets may have different distances from the photographing optical axis to the light source. Furthermore, all the light sources are arranged side by side in the scanning direction. FIG. 9 shows images of two sets of light sources formed on the pupil of the subject's eye and an aperture image of the diaphragm. In this case, an exit pupil is formed on the pupil by the images of the two sets of light sources, and an entrance pupil is formed by the aperture image of the diaphragm.

Which of the two sets is used for imaging may be selected depending on the pupil diameter of the eye to be examined. That is, in the normal photographing mode, the control unit 100 may select a light source from a set of light sources arranged on the outer side. In this case, the reflected image is likely to be reduced. Furthermore, in the small pupil imaging mode, the control unit 100 may select a light source from a set of light sources arranged more inside. In the small pupil imaging mode, artifacts are likely to occur because the clearance between the entrance pupil and the exit pupil is narrowed. Therefore, the photographed image may be photographed by setting the period during which the first area passes through the optical path as the exposure period. On the other hand, in the normal photographing mode, since the clearance between the entrance pupil and the exit pupil is wide, the photographed image may be photographed using the period during which the second area passes through the optical path as the exposure period.

1 Fundus photographing device 10 Photographing optical system 10a Irradiation optical system 10b Light receiving optical system 22 Objective lens 100 Control unit 150 Optical chopper E Test eye Er Fundus

Claims (4)

an imaging optical system including an irradiation optical system that irradiates illumination light onto the fundus of the eye to be examined; and a light reception optical system that includes an image sensor that receives the return light of the illumination light from the fundus; A fundus imaging device that obtains a fundus image, which is a frontal image of the fundus, based on a signal,
comprising control means;
The photographing optical system is
an optical element for forming a local imaging area in a slit shape;
a scanning unit that scans the imaging area with respect to the fundus;
Detecting means for detecting information regarding the size of the pupil of the eye to be examined,
The optical element is capable of switching the width of the imaging area to either a first width or a second width wider than the first width,
The control means operates in a first imaging mode in which a first fundus image based on scanning the imaging area having the first width is acquired as a imaging image, and a second fundus image based on scanning the imaging area having the second width. A fundus photographing apparatus that selects one of a second photographing mode in which an image is acquired as a photographed image based on information regarding the size of the pupil. an imaging optical system including an irradiation optical system that irradiates illumination light onto the fundus of the eye to be examined; and a light reception optical system that includes an image sensor that receives the return light of the illumination light from the fundus; A fundus imaging device that obtains a fundus image, which is a frontal image of the fundus, based on a signal,
comprising control means;

The photographing optical system is
an optical element for forming a local imaging area in a slit shape;
a scanning unit that scans the imaging area with respect to the fundus;
The optical element can switch the width of the imaging area to either a first width or a second width wider than the first width, and A rotating body in which a plurality of slit openings are arranged side by side, the rotating body having a first slit opening corresponding to the first width and a second slit opening corresponding to the second width,
The scanning unit is an optical chopper that includes the rotating body and rotationally drives the rotating body,
The control means operates in a first imaging mode in which a first fundus image based on scanning the imaging area having the first width is acquired as a imaging image, and a second fundus image based on scanning the imaging area having the second width. A fundus photographing device that switches a photographing mode between at least two modes: a second photographing mode in which an image is acquired as a photographed image; The rotating body has a first area in which one or more of the first slit openings are consecutively arranged, and a second area in which one or two or more of the second slit openings are arranged in succession. , comprising;
In the first photographing mode, the control means controls the first fundus image based on a signal from the image sensor exposed during a first period in which the first area passes through the optical path of the illumination light or the return light. and in the second imaging mode, the second fundus image is acquired based on a signal from the image sensor exposed during a second period in which the second area passes through the optical path. fundus imaging device. an imaging optical system including an irradiation optical system that irradiates illumination light onto the fundus of the eye to be examined; and a light reception optical system that includes an image sensor that receives the return light of the illumination light from the fundus; A fundus imaging device that obtains a fundus image, which is a frontal image of the fundus, based on a signal,
comprising control means;
The photographing optical system is
an optical element for forming a local imaging area in a slit shape;
a scanning unit that scans the imaging area with respect to the fundus;
A diopter correction unit for correcting a diopter error in the eye to be examined,
The optical element is capable of switching the width of the imaging area to either a first width or a second width wider than the first width,
The control means operates in a first imaging mode in which a first fundus image based on scanning the imaging area having the first width is acquired as a imaging image, and a second fundus image based on scanning the imaging area having the second width. Switching the shooting mode between at least two of: a second shooting mode in which the image is acquired as a photographed image;
The fundus photographing apparatus, wherein the control means selectively sets either the first photographing mode or the second photographing mode according to a diopter correction amount in the diopter correcting section.