JP2020006172A - Ocular fundus imaging apparatus - Google Patents

Abstract

To acquire an ocular fundus image in which artifact is suppressed.SOLUTION: An ocular fundus imaging apparatus includes a radiation optical system 10a for radiating an illumination light onto the ocular fundus Er through an objective lens 22 and a light reception optical system 10b that shares the objective lens 22 with the radiation optical system 10a and has a light receiving element 28 for receiving an ocular fundus reflection light of the illumination light, and acquires an ocular fundus image on the basis of a signal from the light receiving element 28. The ocular fundus imaging apparatus further includes a diopter correction optical system 17 and 25 for independently adjusting a radiation side correction amount, which is a diopter correction amount in the radiation optical system 10a, and a light receiving side correction amount, which is a diopter correction amount in the light reception optical system 10b, and a control unit for correcting the diopter correction optical system 17 and 25, and setting the radiation side correction amount and the light receiving side correction amount to mutually different values.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a fundus photographing apparatus for obtaining a front image of the fundus.

  2. Description of the Related Art A fundus imaging apparatus that captures a front image of the fundus of a subject's eye is widely used in the ophthalmology field. Examples of the fundus photographing apparatus include the following apparatuses in addition to the fundus camera and the scanning laser ophthalmoscope. For example, in Patent Literature 1, a front image of the fundus is obtained by scanning slit-shaped illumination light on the fundus and sequentially projecting the illuminated image of the fundus region on a two-dimensional imaging surface according to the scanning. An apparatus is disclosed. In many fundus imaging apparatuses, illumination light is projected and received through an objective lens.

JP-B-61-48940

  In an apparatus having an objective lens, under at least some shooting conditions, there is a possibility that reflected light generated on the front surface or the rear surface of the objective lens is reflected as an artifact in a fundus image. The artifact appears as a bright point image (reflection image) near the center of the fundus image. The bright spot image can be an obstacle to diagnosis and observation.

  The present disclosure has been made in view of at least one of the problems of the related art, and has an object to obtain a fundus image in which artifacts are suppressed.

  A fundus imaging apparatus according to a first aspect of the present disclosure includes: an irradiation optical system that irradiates illumination light to a fundus of an eye to be examined via an objective lens; the illumination optical system shares the objective lens with the illumination optical system; A light receiving optical system having an imaging surface on which an image of the fundus is formed based on fundus reflection light, and a photographing optical system including a scanning unit, and a diopter correction optical system that corrects diopter in the photographing optical system. The scanning unit includes: a diaphragm that forms at least one of a local illumination region and a local photographing region in a part of a photographing range in a fundus; and intersects the diaphragm with an optical axis based on a control signal. And a driving unit that drives in a direction in which the diaphragm is arranged, and captures the fundus image in a state where the diaphragm is arranged at a position different from a fundus conjugate position related to the objective lens and the diopter correction optical system.

  A fundus imaging apparatus according to a second aspect of the present disclosure includes: an irradiation optical system that irradiates illumination light to a fundus of an eye to be inspected via an objective lens; the objective lens is shared with the illumination optical system; A light receiving optical system having a light receiving element for receiving fundus reflected light, and a fundus photographing apparatus that obtains a fundus image based on a signal from the light receiving element, wherein a diopter correction amount in the irradiation optical system Controlling the diopter correction optical system and the diopter correction optical system that independently adjust the irradiation-side correction amount and the light-receiving side correction amount that is the diopter correction amount in the light-receiving optical system. Control means for setting the correction amount and the light-receiving-side correction amount to values different from each other.

  According to the present disclosure, it is possible to acquire a fundus image in which artifacts are suppressed.

FIG. 1 is a diagram illustrating an external configuration of an apparatus according to one embodiment. FIG. 2 is a diagram illustrating an optical system housed in a photographing unit, which is an optical system according to a first embodiment. FIG. 2 is a block diagram illustrating a control system of the device according to the embodiment. It is a figure for explaining operation of a diopter correction optical system according to a refractive power of an eye to be examined, and is a figure showing a state of diopter correction when a refractive power is in the 1st range. It is a figure for explaining operation of a diopter correction optical system according to a refractive power of an eye to be examined, and is a figure showing a state of diopter correction when a refractive power is in a 2nd range. FIG. 8 is a diagram for explaining adjustment control of a diopter correction value in consideration of the size of the pupil in addition to the refractive power of the eye to be examined. It is a figure for explaining an outline of the 2nd artifact suppression processing. It is a figure for explaining an outline of the 3rd artifact suppression processing. FIG. 3 is a diagram illustrating a manner of irradiating illumination light to the fundus and scanning by the optical system of FIG. 2. FIG. 3 is a diagram illustrating a manner of irradiating illumination light to the fundus and scanning by the optical system of FIG. 2. It is a figure for explaining the outline of the 4th artefact suppression processing, and shows a fundus image obtained when irradiating illumination light from two projection areas simultaneously. It is a figure for explaining the outline of the 4th artefact suppression processing, and shows a fundus image obtained when illumination light is irradiated selectively from one of two projection areas. It is a figure for explaining the outline of the 5th artifact control processing. FIG. 3 is a diagram illustrating an optical chopper applicable as a scanning unit in the optical system of FIG. 2. It is a figure for explaining the outline of the 6th artefact suppression processing, and especially shows an example using an optical chopper in which a plurality of slits with different widths were formed. FIG. 8 is a diagram illustrating an optical system housed in a photographing unit, which is an optical system according to a second embodiment. 6 is a flowchart illustrating a photographing operation of the device.

"Overview"
Hereinafter, an embodiment of a fundus imaging apparatus according to the present disclosure will be described with reference to the drawings. In the following, in each of the first to third embodiments, an apparatus is disclosed in which artifacts caused by reflection / scattering in the eye to be inspected or inside the apparatus are suppressed. Each embodiment can appropriately utilize a part or all of the other embodiments.

<First embodiment>
First, a first embodiment will be described. In the first embodiment, the fundus imaging apparatus (see FIG. 1) has at least an imaging optical system (for example, see FIG. 2) and a control unit (for example, see FIG. 3). The fundus imaging apparatus may additionally include a refractive power information acquisition unit.

<Control unit>
The control unit is a processing device (processor) that performs control processing of each unit in the fundus imaging apparatus and arithmetic processing. For example, the control unit is realized by a CPU (Central Processing Unit), a memory, and the like. In the present embodiment, the control unit may also serve as an image processing unit (imaging processor). The image processing unit performs at least one of generation of a fundus image and various types of image processing on the fundus image.

<Shooting optical system>
The photographing optical system is used for projecting and receiving illumination light to and from the fundus of the subject's eye via an objective lens to photograph a fundus image. In the first embodiment, the photographing optical system has an irradiation optical system, a light receiving optical system, and a diopter correction optical system (see FIGS. 2, 4A, and 4B).

  The irradiation optical system irradiates illumination light to the fundus of the subject's eye via the objective lens. Additionally, the illumination optical system may include a light source that emits illumination light (illumination light source). The light receiving optical system has a light receiving element that receives the fundus reflected light of the illumination light. The light receiving optical system forms an image of the fundus oculi on the imaging surface based on the fundus reflection light of the illumination light. The signal from the light receiving element is input to the image processing unit. In the image processing unit, an image formed on the imaging surface is obtained (generated) as a fundus image based on a signal from the light receiving element. In the present disclosure, a front image of the fundus is referred to as a “fundus image”.

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

  The imaging optical system may be a scanning optical system that performs imaging by scanning illumination light on the fundus. Further, the imaging optical system may be a non-scanning optical system. Examples of a scanning optical system include a spot scan optical system and a line scan optical system. In a spot scan type optical system, spot-like illumination light is two-dimensionally scanned on the fundus. In a line scan type optical system, linear illumination light is scanned in one direction. For example, the linear illumination light may be linearly scanned on the fundus, or may be rotationally scanned on the fundus. In the case of rotational scanning, the center of rotation may be the optical axis of the imaging optical system (hereinafter, also referred to as “imaging optical axis”). In the scanning optical system, any one of a point light receiving element, a line sensor, a two-dimensional light receiving element (photographing element), and the like can be appropriately adopted as the light receiving element. An example of a non-scanning optical system is an optical system of a general fundus camera.

<Diopter correction optical system>
The diopter correction optical system (see FIGS. 2, 4A, and 4B) is used to correct the diopter of the photographing optical system according to the refractive power of the eye to be inspected. The refractive power of the subject's eye is also referred to as a refractive error and a diopter value. In the present embodiment, the diopter correction optical system includes a diopter correction amount in the irradiation optical system (hereinafter, referred to as “irradiation-side correction amount”) and a diopter correction amount in the light-receiving optical system (hereinafter, “light-receiving-side correction amount”). ) Are adjusted independently.

  The diopter correction optical system may be separately arranged at two or more locations of the photographing optical system. In this case, the diopter correction optical system may include a first diopter correction optical system and a second diopter correction optical system. The diopter correction amount in the first diopter correction optical system and the diopter correction amount in the second diopter correction optical system are set independently. For example, the first diopter correction optical system may be disposed on one optical path of the irradiation optical system and the light receiving optical system, and in this case, the second diopter correction optical system may be disposed on the other optical path with respect to one. Alternatively, they may be arranged on a common optical path of the irradiation optical system and the light receiving optical system.

  In the present embodiment, a first driver (first driver) and a second driver (second driver) may be provided. The first drive unit and the second drive unit are independently controlled by the control unit. The first drive unit drives at least one optical element included in the first diopter correction optical system. The second drive unit drives at least one optical element included in the second diopter correction optical system.

  When the second diopter correction optical system is arranged in the common optical path, the diopter correction amount in the other optical system is the diopter correction amount in the first diopter correction optical system and the diopter correction amount in the second diopter correction optical system. And the diopter correction amount at For convenience of explanation, one or both of the first diopter correction optical system and the second diopter correction optical system that affect the diopter of the irradiation optical system are referred to as an “irradiation-side diopter correction optical system” and receive light. One or both that affect the diopter of the optical system may be referred to as a “light-receiving-side diopter correction optical system”.

  By the way, the position conjugate with the fundus of the objective lens (that is, the position of the intermediate image plane of the fundus) is displaced according to the refractive power (mainly, the spherical power) of the eye to be examined. In FIGS. 4A and 4B, the position of the intermediate image plane is indicated by reference numeral J. In the present embodiment, the diopter correction optical system disposed between the objective lens and the imaging surface is driven so that the intermediate image plane and the imaging surface of the light receiving optical system have a conjugate relationship, thereby forming a fundus. Is well formed on the imaging surface.

  In the present disclosure, “conjugate” is not necessarily limited to a perfect conjugate relationship, but includes “substantially conjugate”. In other words, a case where the components are displaced from a perfect conjugate position within a range permitted in relation to the technical significance of each unit is also included in the “conjugate” in the present disclosure.

  Also, if diopter correction is performed in the irradiation optical system, it is considered that, for example, errors in the illumination range are suppressed, and the light amount distribution of the illumination light on the fundus becomes easy to be uniform. However, the condensing position in the irradiation optical system is displaced along the optical axis according to the irradiation-side correction amount. Specifically, as the irradiation-side correction amount shifts to the minus diopter side, it is considered that the condensing position approaches the objective lens. In FIGS. 4A and 4B, the light condensing position is indicated by a symbol K. When the focusing position approaches the surface of the objective lens (that is, the front surface or the rear surface), the reflection of the illumination light by the objective lens may be easily reflected in the fundus image as an artifact. That is, if the irradiation-side correction amount is adjusted in accordance with the refractive power, the more the refractive power of the eye to be examined is a value on the minus diopter side (for example, the more the myopic eye has a higher power), Artifacts are likely to occur.

<Artifact suppression by making the irradiation-side correction amount and the light-receiving-side correction amount inconsistent>
On the other hand, the control unit may adjust the irradiation-side correction amount and the light-receiving-side correction amount to different values by controlling the diopter correction optical system (see FIG. 4B). For example, the control unit may adjust the light-receiving-side correction amount according to the refractive power of the eye to be inspected. More specifically, the light-receiving-side correction amount may be adjusted to a diopter substantially equal to the refractive power.

  At this time, the control unit may further adjust the focusing position of the illumination light via the diopter correction optical system with reference to the intermediate image of the fundus oculi formed via the objective lens (see FIG. 4B). More specifically, the irradiation-side correction amount may be adjusted such that the focusing position is further away from the objective lens with respect to the intermediate image. Thereby, an image of the fundus oculi is easily formed well on the imaging surface, and the occurrence of artifacts due to the reflection of the objective lens is suppressed. As a result, a good fundus image is captured.

  At this time, the irradiation-side correction amount may be adjusted so that the absolute value is smaller than the light-receiving-side correction amount. As the difference between the irradiation-side correction amount and the light-receiving-side correction amount increases, various effects such as a decrease in the amount of received light are more likely to occur. Therefore, by limiting each correction amount so that a large difference does not occur between the irradiation-side correction amount and the light-receiving-side correction amount, it is possible to obtain a fundus image with good image quality while suppressing the occurrence of artifacts. Can be.

  When adjusting the irradiation-side correction amount and the light-receiving-side correction amount to values different from each other, the control unit may adjust the irradiation-side correction amount to a constant value regardless of the light-receiving-side correction amount. However, the present invention is not necessarily limited to this, and in the same case, the irradiation-side correction amount may be adjusted to a different value for each light-receiving-side correction amount.

  However, it is not necessary to always adjust each irradiation so that the irradiation-side correction amount and the light-receiving-side correction amount have different values. For example, under predetermined imaging conditions, the irradiation-side correction amount and the light-receiving-side correction amount may match each other. Here, the imaging conditions under which the artifact does not matter can be checked in advance by experiments, optical simulations, and the like. For example, the range of the diopter correction amount in which the artifact does not occur when the irradiation-side correction amount and the light-receiving-side correction amount are matched may be predetermined as the imaging condition. When the irradiation-side correction amount and the light-receiving-side correction amount match each other, each of the irradiation-side correction amount and the light-receiving-side correction amount may be adjusted to a diopter substantially equal to the refractive power.

<Switching the shooting mode according to the refractive power>
In the present embodiment, the control unit may switch the imaging mode of the apparatus between the first imaging mode and the second imaging mode according to the refractive power of the eye to be inspected. In the second shooting mode, the diopter correction optical system is controlled such that the “difference value” is larger than in the first shooting mode. The difference value here indicates a difference between the irradiation-side correction amount and the light-receiving-side correction amount. As an example, in the first photographing mode, photographing may be performed with the irradiation-side correction amount and the light-receiving-side correction amount coincident with each other (see FIG. 4A). In this case, both the irradiation-side correction amount and the light-receiving-side correction amount may be adjusted to a value corresponding to the refractive power. Further, in the second shooting mode, shooting may be performed with the irradiation-side correction amount and the light-receiving-side correction amount being different from each other (see FIG. 4B). In this case, as an example, the control unit may adjust the light-receiving-side correction amount according to the refractive power of the subject's eye and set the irradiation-side correction amount to a value having a smaller absolute value with respect to the light-receiving-side correction amount. Good.

  The refractive power of the eye to be examined may be roughly divided into a first range and a second range on the minus diopter side with respect to the first range. The second range is different from the first range in that an intermediate image plane of the fundus reflection light formed via the objective lens (mainly, an intermediate image plane formed closest to the objective lens) is: This range is closer to the rear surface of the objective lens. In FIGS. 4A and 4B, the range of the diopter correction amount corresponding to the first range is the range illustrated by reference numeral A1. Further, the range of the diopter correction amount corresponding to the second range is the range illustrated by reference numeral A2.

  The shooting mode may be switched between a case where the refractive power is in the first range and a case where the refractive power is in the second range. The control unit may switch to the first photographing mode when the refractive power is within the first range. Further, the control unit may switch to the second shooting mode when the refractive power is in the second range.

  The value of the refractive power serving as the threshold between the first range and the second range can be checked in advance by, for example, experiments and optical simulations. For example, when changing the diopter correction amount in the diopter correction optical system from the plus diopter side to the minus diopter side while matching the irradiation side correction amount and the light receiving side correction amount, the reflection of the objective lens causes A value at which an artifact starts to occur may be determined as a threshold.

<Scanning imaging optical system>
Meanwhile, as a scanning type imaging optical system, an apparatus having a harmful light removing unit and a scanning unit is known. In a scanning type imaging optical system, an irradiation optical system forms a local illumination region in a part of an imaging range on a fundus. As a typical example, an apparatus that forms an illumination area in a slit shape or a spot shape is known.

  The harmful light removing unit is disposed on the optical path of the light receiving optical system with the diopter correction optical system interposed between the harmful light removing unit and the objective lens, for example. In this case, the harmful light removing unit may be arranged at a position conjugate with the fundus with respect to at least the objective lens and the diopter correction optical system in a state where the correction amount on the light receiving side according to the refractive power of the eye to be inspected is set.

  The harmful light removing unit causes the light receiving element to receive fundus reflected light from a local imaging region (hereinafter, referred to as an “effective region”) that is a part of the imaging range. The harmful light removing unit is used for removing light from areas other than the effective area. The harmful light removing unit may be, for example, an aperture. A typical stop in a spot scan type apparatus is a pinhole, and a typical stop in a slit scan type apparatus is a slit. In this case, the fundus reflection light from the effective area corresponding to the aperture of the stop in the entire photographing range on the fundus is selectively guided to the light receiving element, and is acquired as an effective image. In particular, in a slit scan type device, the light receiving element itself may be used as a harmful light removing unit. In this case, a line sensor may be used as the light receiving element, or a CMOS having a rolling shutter function may be used. The line sensor is formed in a slit shape. In a CMOS having a rolling shutter function, line exposure is performed on a two-dimensional imaging surface. The fundus reflection light from the effective area corresponding to the line-shaped effective pixel in the entire fundus imaging range is selectively guided to the imaging surface, so that an image of the effective area is captured.

  The scanning unit scans the local illumination region and the effective region (local imaging region) on the fundus in synchronization with each other. The scanning unit may be, for example, an optical scanner shared between the irradiation optical system and the light receiving optical system. In this case, the optical scanner is arranged on a common optical path of the irradiation optical system and the light receiving optical system.

  The scanning unit may include a first scanning unit provided in the irradiation optical system, and a second scanning unit provided separately from the first scanning unit and provided in the light receiving optical system. In this case, in an example of a slit scan type device, a first slit-shaped member (an example of a stop) is arranged on an optical path of an irradiation optical system in order to form a local illumination region in a slit shape. Is also good. The first scanning unit may include a first slit-shaped member and a driving unit that moves the first slit-shaped member in a direction intersecting the optical axis. Further, when the second slit-shaped member is used as the harmful light removing unit, the second scanning unit includes a second slit-shaped member (an example of an aperture) and a drive for moving the second slit-shaped member in a direction intersecting the optical axis. And a part. The driving unit of the first scanning unit and the driving unit of the second scanning unit may be separate devices or may be a common device.

  In the case where a CMOS is used as the light receiving element in the slit scan type device, the CMOS may also serve as the second scanning unit. That is, the line exposure by the rolling shutter function may be controlled in synchronization with the first scanning unit. In this case, the CMOS which is the light receiving element also serves as the harmful light removing unit and the second scanning unit. Thereby, the number of parts of the optical system is suppressed.

<Suppression of image height change due to diopter correction>
In the above-described scanning type imaging optical system, if a position shift occurs between the illumination area and the effective area on the fundus, the amount of received light decreases or an image cannot be obtained at all. It is possible.

  On the other hand, the diopter correction optical system may include a telecentric optical system. In the telecentric optical system, between the case where the irradiation-side correction amount and the light-receiving side correction amount coincide with each other and the case where they are different from each other, in each of the irradiation optical system and the light receiving optical system, the image is better than the diopter correction optical system. Maintain the image height in the side area. However, in both the irradiation optical system and the light receiving optical system, the eye to be inspected is referred to as an object side, and the opposite side of the diopter correction optical system from the eye to be inspected is referred to as an image side. Even if the irradiation-side correction amount and the light-receiving-side correction amount do not match, a position shift between the illumination area and the effective area on the fundus is unlikely to occur due to the telecentric optical system. Therefore, the above-described telecentric optical system has an effect that, in an apparatus having a scanning-type photographing optical system, a fundus image can be photographed favorably when the occurrence of artifacts is suppressed. However, the telecentricity of the optical system according to the embodiment may be imperfect within an allowable accuracy range.

  Note that, more specifically, the telecentric optical system may include a first telecentric optical system and a second telecentric optical system. The first telecentric optical system maintains an image height in a region closer to the image than the diopter correction optical system regardless of a change in the light-receiving-side correction amount. The second telecentric optical system maintains the height of the principal ray of the illumination light on the fundus irrespective of a change in the irradiation-side correction amount.

  The above-described telecentric optical system is also useful for a non-scanning optical system. That is, a change in magnification of the fundus image and a change in illumination unevenness due to diopter correction are suppressed by the telecentric optical system.

<Adjustment of shooting conditions according to diopter correction amount>
As a result of adjusting the irradiation-side correction amount to a value different from the light-receiving-side correction amount, for example, the following phenomenon may occur. For example, the outer edge of a region on the fundus irradiated with the illumination light may be blurred. Further, the position of the region irradiated with the illumination light may be shifted from the position of the effective region. When these phenomena occur, the amount of received light is more likely to be reduced than when the irradiation-side correction amount and the light-receiving side correction amount match.

  On the other hand, in the present embodiment, between the first shooting mode and the second shooting mode, the control unit determines whether at least one of the amount of illumination light applied to the fundus, the gain of the light receiving element, and the exposure time. May be switched. More specifically, in the second shooting mode, at least one of the amount of illumination light, the gain of the light receiving element, and the exposure time is increased in the second shooting mode. Thus, even when the irradiation-side correction amount and the light-receiving-side correction amount do not match, a fundus image with a wide dynamic range can be obtained. Note that the control unit may reduce the scanning speed to increase the exposure time. Further, in an apparatus that continuously captures a plurality of fundus images and adds a plurality of images to capture one captured image, increasing the number of fundus images used for addition increases the exposure time. Can be substantially increased.

<Refractive power acquisition unit>
The refractive power information obtaining unit obtains refractive power information as information on the refractive power of the subject's eye.

  For example, the refractive power information acquiring unit may be a measuring unit. In this case, refractive power information is acquired as a result of the measurement for the eye to be examined.

  At least a part of the photographing optical system may be used for the measurement unit as the refractive power information acquisition unit. For example, the refractive power information acquisition unit may detect a focus state in the light receiving optical system, and acquire refractive power information based on a detection result of the focus state. More specifically, the focus state is detected while changing the light-receiving-side correction amount, which is the diopter correction amount in the light-receiving optical system, and the value of the light-receiving-side correction amount when the best focus state is obtained is determined by the refraction. It may be acquired as frequency information. However, the refractive power information is not necessarily limited to the light-receiving-side correction amount. For example, any of a drive amount in a drive unit driven to change the light-receiving-side correction amount (or the irradiation-side correction amount), position information of an optical element displaced by the drive unit, or the like is used as refractive power information. Can be used.

  The focus state may be detected based on a fundus image acquired via the photographing optical system. In this case, the focus state may be detected as contrast information of the fundus image. Further, the focus state may be detected based on a fundus image in which the index image of the focus index is reflected. As an example of the focus index, a split index is known (see FIG. 2). The split target is projected on the fundus as two target images separated by the prism. The focus state may be detected based on the positional relationship between the two index images. In this case, the refractive power information acquisition unit includes an index projection unit that projects the focus index.

  Note that the refractive power information acquisition unit is not necessarily limited to the measurement unit. For example, the refractive power information acquiring unit may be configured to receive refractive power information measured in advance by a device separate from the fundus photographing device, and to thereby acquire the refractive power information. In this case, the refractive power information acquisition unit may include a control unit, a port, and the like. The port is used to connect any one of a separate device, an external storage medium, and a user interface to the ophthalmic measurement device. As a separate device, for example, there is a subjective or objective refraction inspection device. The external storage medium may store refractive power information in advance. The control unit may obtain the information by reading the refractive power information from the storage medium. Also, the user interface may be used to manually enter refractive power information. In this case, the refractive power information may be acquired as an input result by the examiner.

<Adjustment of difference value between irradiation-side correction amount and light-receiving-side correction amount in consideration of pupil diameter>
The positional relationship between the pupil of the subject's eye and the light projecting area and the light receiving area in the imaging optical system may be changeable according to the size of the pupil of the subject's eye. In the present disclosure, a region where the illumination light is projected on the pupil of the subject's eye is referred to as a “light projection region”, and a region where the fundus reflection light by the illumination light is extracted on the pupil is referred to as a “light receiving region”. .

  As an example, the clearance between the light projecting area and the light receiving area may be changeable. By narrowing the clearance, it becomes easier to photograph the small pupil eyes. However, in this case, if the clearance is narrowed, an artifact based on light reflected by the objective lens is likely to occur.

  As another example, the alignment position in the XY directions (up, down, left, and right directions) may be changeable. If the eyes are small pupils and vignetting occurs in a part of the light projecting area and the light receiving area, the alignment reference position in the XY directions may be appropriately changed. By appropriately changing the alignment state, the balance between light emission and reception can be improved. However, the range of the diopter correction amount in which an artifact based on the reflected light from the objective lens occurs may change according to the alignment state in the XY directions.

  On the other hand, the control unit may adjust the difference value between the irradiation-side correction amount and the light-receiving-side correction amount according to the size of the pupil of the subject's eye. For example, in the case of a first pupil diameter, the first pupil diameter is adjusted to a first difference value, and in the case of a second pupil diameter smaller than the first pupil diameter, a second difference larger than the first difference value is adjusted. It may be adjusted to a value (see FIG. 5). Thereby, even if the positional relationship between the pupil of the subject's eye and the light projecting area and the light receiving area in the photographing optical system is changed according to the size of the pupil of the subject's eye, a fundus image with suppressed artifacts is taken. Can be done. The control unit may control the difference value in conjunction with the above-described positional relationship control.

  In the case where the difference value is adjusted according to the size of the pupil, the fundus imaging apparatus may further include a pupil information acquisition unit that acquires information indicating the size of the pupil (referred to as pupil information). The pupil information acquisition unit may include, for example, an anterior segment imaging optical system that captures an anterior segment image of the subject's eye, and an image processing unit that acquires pupil information from the anterior segment image.

<Second embodiment>
Next, a second embodiment will be described.

  The fundus imaging apparatus according to the second embodiment executes a process for suppressing artifacts due to the reflection of the objective lens (hereinafter, referred to as an artifact suppression process). In the second embodiment, the artifact suppression processing is automatically executed when the refractive power of the subject's eye falls within a predetermined range. On the other hand, when the refractive power is out of the range, the artifact suppression processing is not performed. As described above, in the second embodiment, the invalid mode in which the artifact suppression processing is disabled when capturing the fundus image (that is, the processing is not performed), and the artifact suppression processing is enabled when capturing the fundus image. The control unit switches the photographing mode between the effective mode (that is, executes the processing) and the effective mode based on the refractive power.

  As described in the first embodiment, when the diopter correction is performed in accordance with the refractive power in both the irradiation optical system and the light receiving optical system, the more the refractive power is on the minus diopter side, the more the artifact is likely to occur. Become. Therefore, in the second embodiment, the refractive power is included in the first range and the refractive power is included in the second range (minus diopter side with respect to the first range). In this case, the mode may be set to the invalid mode, and in the latter case, the mode may be set to the valid mode. As a result, a fundus image in which the occurrence of artifacts is suppressed is obtained regardless of the refractive power of the eye to be examined. In addition, when photographing an eye to be inspected in which the refractive power is relatively on the plus diopter side and artifacts are unlikely to occur, the influence on the fundus image based on the artifact suppression processing, and the burden on the examinee due to the imaging, etc. At least one is prevented.

  In addition, the diopter correction optical system for setting the irradiation-side correction amount (the diopter correction amount in the irradiation optical system) and the light-receiving-side correction amount (the diopter correction amount in the light receiving optical system) in the first embodiment to a mismatch state. The drive processing of the system is cited as an example of various artifact suppression processing. However, the artifact suppression processing in the second embodiment is not necessarily limited to this. For example, in the artifact suppression process, a plurality of fundus images having different positions of the artifact with respect to the tissue of the eye to be examined may be captured, and a plurality of fundus images may be combined to generate a combined image (for example, 2nd and 6th artifact suppression processing). Further, various operations exemplified in the following description may be adopted.

  Hereinafter, the detailed configuration of the second embodiment will be described focusing on the differences from the first embodiment. The fundus imaging apparatus according to the second embodiment has at least an imaging optical system, an image processing unit, a refractive power acquisition unit, and a control unit. For each of these components, the items of <control unit>, <image processing unit>, <photographing optical system>, and <refractive power acquisition unit> in the description of the first embodiment can be used as appropriate.

<Second artifact suppression processing>
In the second artifact suppression processing, the fundus image is photographed at least twice by switching the positional relationship between the photographing optical axis and the visual axis of the eye to be inspected. Further, a plurality of fundus images obtained by at least two shootings are combined by the image processing unit. As a result, the device acquires a combined image that is a fundus image in which artifacts are suppressed (see FIG. 6). In FIGS. 6 to 11, artifacts are indicated by reference numeral N or reference numerals N1 and N2. The image processing unit is configured to convert an area including an artifact in at least one of the plurality of fundus images (referred to as a first fundus image) into an image area having the same positional relationship with respect to the fundus tissue and the other fundus image. A complementary image is generated by performing complementation using the image area. More specifically, a region including an artifact in at least one of a plurality of fundus images may be replaced with a corresponding image region in another image. Further, an area including an artifact may be complemented by image addition of a plurality of fundus images.

  In order to execute the second artifact suppression processing, the fundus imaging apparatus may include a position adjustment unit. The position adjustment unit adjusts an occurrence position of an artifact with respect to the fundus tissue in the fundus image by changing a positional relationship between the imaging optical axis and the visual axis of the eye to be inspected. The position adjustment unit may include a fixation optical system. The fixation optical system presents a fixation target to the eye to be examined. The fixation optical system may be capable of switching the presentation position of the fixation target to a plurality of positions in a direction intersecting with the photographing optical axis. In addition, the position adjustment unit may include a driving unit that moves the imaging optical system with respect to the eye to be inspected. For example, the drive unit may change the positional relationship between the photographing optical axis and the visual axis of the subject's eye by turning the photographing optical system around the anterior segment of the subject's eye. Of course, the position adjustment unit may include both the fixation optical system and the drive unit.

  For more details regarding the second artifact suppression processing, refer to, for example, Japanese Patent Application Laid-Open No. 2017-184787 by the present applicant.

<Third artifact suppression processing>
In the third artifact suppression process, a background difference based on the fundus image and the background image is executed by the image processing unit, and as a result, a fundus image in which artifacts are suppressed is generated (see FIG. 7). The background image referred to here is a background image for the fundus image, and includes at least an artifact due to the objective lens. The background image may be an image captured in a state where the front side of the objective lens is covered with a lid such as a lens cover.

  For more details regarding the third artifact suppression processing, refer to, for example, Japanese Patent Application Laid-Open No. 2017-217076 by the present applicant.

<Apparatus Configuration as Premise of Fourth and Fifth Artifact Suppression Processing>
All of the fourth and fifth artifact suppression processes are based on the premise that the imaging optical system has the following configuration. That is, the photographing optical system is a slit scan type optical system. For example, the optical system shown in FIG. 2 may be used. The imaging optical system has at least a slit forming unit, a scanning unit, and a light emitting / receiving unit. In addition, the imaging optical system may include a light source, an image sensor, an optical path branching unit, and the like.

  The slit forming unit forms the illumination light in a slit shape on the fundus of the eye to be inspected. The slit forming portion may be, for example, a slit-shaped light transmitting portion (for example, an opening) arranged in a plane conjugate with the fundus.

  As shown in FIGS. 2 and 8, the scanning unit scans the illumination light formed in a slit shape on the fundus in a direction crossing the slit (specifically, a direction crossing the longitudinal direction of the slit). . The scanning unit may scan the illumination light by moving the slit forming unit in a direction intersecting the slit. Examples of this type of scanning unit include a mechanical shutter, a liquid crystal shutter, an optical chopper (see FIG. 12), a drum reel, and the like.

  The scanning direction of the slit is preferably a direction orthogonal to the slit. However, the direction may be oblique to the direction orthogonal to the slit.

  Further, the scanning unit may be a member that changes the direction of light passing through the slit forming unit. For example, various optical scanners such as a galvano scanner may be used as the scanning unit. A scanning unit of a type that scans by rotating light, such as a galvano scanner, may be placed at a position conjugate with the pupil of the eye to be examined.

  The imaging optical system may further include an optical path coupling unit and an objective lens.

  The optical path coupling unit couples and separates the projection optical path of the illumination light and the light reception optical path of the fundus reflection light. The objective lens is arranged on a common optical path formed by the optical path coupling section and the light transmitting optical path and the light receiving optical path. At this time, it is desirable that the photographing optical axis coincides with the optical axis of the objective lens.

  Various beam splitters can be used as the optical path coupling unit. In this case, the optical path coupling unit may be a perforated mirror, a simple mirror, a half mirror, or another beam splitter.

  The light projection / reception separation unit separates a light projection area and a light reception area on the pupil of the eye to be inspected.

  Specifically, as shown in FIGS. 2 and 9, the light emitting / receiving section separates the light emitting area into two positions separated from each other in the scanning direction of the illumination light. The two light projecting regions may be formed so as to sandwich the photographing optical axis. In the first embodiment, the light-projecting / receiving separation unit may be one that forms at least two light-projecting regions, and may be one that forms three or more light-projecting regions. The illumination light that has passed through each light projecting area illuminates the same slit-shaped area on the fundus. Then, as the scanning unit is driven, the slit-shaped area is scanned.

  As shown in FIG. 9, the light receiving / receiving section is formed so that the light receiving area is sandwiched between the two light emitting areas. That is, the regions are formed in a line in the order of one light emitting region, light receiving region, and the other light emitting region. Further, the light receiving region may be formed on the photographing optical axis. The light emitting area and the light receiving area may be arranged so as not to overlap each other. In that case, it is reduced that a part of the illumination light is reflected and scattered in the cornea and the intermediate light transmitting body, and flare is generated in the fundus image.

  The light projection / reception separation unit may include a plurality of members arranged on the light projection light path of the illumination light and the light reception light path, respectively.

  The light-projection / light-reception separating unit partially sets the irradiation position of the illumination light at at least two positions apart from each other with respect to the scanning direction of the illumination light, for example, on a pupil conjugate plane in the light-projecting optical path of the illumination light. It may be. In this case, the illumination position may be set by arranging the illumination light sources at two positions on the pupil conjugate plane. Alternatively, the illumination position may be set by arranging apertures through which illumination light from the light source passes as apparent illumination light sources at two positions on the pupil conjugate plane.

  In other words, the light projection / reception separation unit includes at least two illumination light sources or two apparent illumination light sources that are arranged at positions different from each other in the scanning direction at a position conjugate with the pupil of the subject's eye. There may be. As a result, the light projection area is formed at two positions separated from each other in the scanning direction of the illumination light. More preferably, the two illumination light sources, or the two apparent illumination light sources, may be arranged symmetrically with respect to the imaging optical axis. Thereby, two light projection areas can be formed symmetrically with respect to the photographing optical axis. The state of light emission from the two illumination light sources or the two apparent illumination light sources may be controllable for each light source by a control unit described later. As a result of controlling the light projection state for each light source, whether or not to transmit the illumination light is individually set for each light projection area. Needless to say, the number of illumination light sources included in the light emitting / receiving separation unit or the number of apparent illumination light sources may be three or more.

  The light projection state may include at least two types of states: a state where illumination light from an illumination light source or an apparent illumination light source reaches the subject's eye and a state where illumination light does not reach the eye. The switching of the projection state may be realized by controlling the lighting of the light source. Further, the light projection state may be switched using an illumination light source or a shutter that selectively blocks a light beam from the apparent illumination light source toward the subject's eye.

  In addition, the light-projecting / receiving separation unit partially passes the fundus reflection light from the light-receiving area, which is an area sandwiched between the two light-projecting areas, on the pupil conjugate plane in the light-receiving optical path of the illumination light to the imaging surface side. Alternatively, other light may be prevented from passing through to the imaging surface side. For example, the light projection / reception separation unit may include a light blocking member that allows the fundus reflection light from the light reception area to pass to the imaging surface side and blocks other light. The light blocking member may be arranged on the pupil conjugate plane in the light receiving optical path, for example. For example, when a stop having an opening centered on the photographing optical axis is provided as a light blocking member, a light receiving region is formed by an opening image of the stop.

  When a light-shielding member is included in the light-projecting / receiving separation unit, the light-shielding member may be shared with the above-described optical path coupling unit or may be a separate unit.

<Fourth artifact suppression processing>
In the above-described apparatus configuration, the control unit may individually set whether or not to transmit the illumination light for the two light-projection regions on the pupil of the subject's eye. In this case, the control unit may capture a fundus image based on the illumination light selectively projected from one (any one) of the two projection areas.

  By the way, in the vicinity of the photographing optical axis in the fundus image, a reflected image (a kind of bright spot image or a kind of artifact) may be generated due to the reflection of the illumination light at the center of the lens surface of the objective lens. Since the light projection area is far from the photographing optical axis, the reflected image is likely to appear at a position slightly deviated from the position of the photographing optical axis in the fundus image. As an example, FIG. 10A illustrates a fundus image captured by simultaneously projecting illumination light from both of the two projection areas. As shown in FIG. 10A, corresponding to the two light projecting regions, reflected images (indicated by reference numerals N1 and N2) may be generated at two positions on the image center of the fundus image with the photographing optical axis interposed therebetween. The two reflected images appear side by side in the scanning direction (in other words, at different positions in the scanning direction).

  In contrast, in the present embodiment, the illumination light is selectively projected from one of the two projection areas to the fundus, and a fundus image is captured. As a result, the position of the objective lens where a reflected image is generated is reduced by half compared to the above case. As a result, as shown in FIG. 10B, the reflection image in the fundus image can be reduced by half. As described above, selectively projecting the illumination light from one of the two light projecting regions on the pupil of the subject's eye to the fundus and photographing the fundus image is advantageous in reducing artifacts. is there.

<Fifth Artifact Suppression Processing>
The control unit selectively emits illumination light to the fundus from one of the two light projection areas to capture the first fundus image, and further sets the light emission area where the illumination light is projected to the other. To the second fundus image by selectively projecting illumination light from the other side. By performing such two shootings, two fundus images are obtained in which the appearance positions of artifacts such as a reflection image by the objective lens are different from each other depending on the projection area used for the shooting. The imaging may be performed between the first imaging and the second imaging without changing the positional relationship between the subject's eye and the imaging optical system. Further, it is desirable that the photographing of the second fundus image be performed continuously and automatically from the photographing of the first fundus image.

  In the present embodiment, when two fundus images are taken, there is no need to change the positional relationship between the subject's eye and the imaging optical system, and the light source is switched on or off, or the shutter is driven. The light projection area on the pupil of the subject's eye can be switched in a short time. Therefore, two fundus images can be captured in a short time. As a result, even if the first fundus image and the second fundus image are continuously photographed, the burden on the subject is suppressed. Even if the illumination light is visible light, the second image is taken immediately after the first image is taken, so that the miosis caused by the first image is given in the second image. The effect can be suppressed.

  Here, examples of the effect of the miosis include that the illumination light and the fundus reflection light are vignetted by the iris, thereby darkening the fundus image. The effect of vignetting (change in brightness) between the center of the image and the periphery of the image is not always uniform. For example, the periphery of an image may be more susceptible to vignetting as the shooting angle of view increases.

  In the fifth artifact suppression process, a single fundus image (hereinafter, referred to as a “combined image”) may be generated by performing a combining process on these two fundus images. The combining process is performed by the image processing unit. In the present embodiment, a combining process is performed to obtain an image in which the influence of the artifact is suppressed. There are various synthesis methods as exemplified below.

  For example, a composite image may be generated by replacing a region including an artifact in one fundus image among two fundus images with a part of the other fundus image corresponding to the region (see FIG. 11). ). At this time, replacement may be performed in units of scanning lines. For example, when the above-described reflection image occurs as an artifact, a composite image may be generated by replacing a reflection image generated at the image center of one fundus image with a corresponding region in the other fundus image.

  Further, a composite image may be generated as an average image of two fundus images. In this case, the averaging process may be performed by giving different addition ratios between the reflection image and the other regions.

  The area where the reflection image occurs is a substantially constant range based on the photographing optical axis although there is some variation depending on the diopter. For this reason, in the two fundus images, the region to be combined with the other image in the combining process may be determined in advance. However, the present invention is not limited to this, and the detection processing of the reflection image may be performed on the fundus image, and the regions to be combined may be individually set based on the result of the detection processing. Further, an area to be combined may be set according to the diopter.

  In addition, the control unit captures the first fundus image based on scanning of only a part of the scanning range corresponding to the composite image, switches the light projection area, and then performs control based on the remaining part of the scanning. A composite image may be generated by taking a second fundus image and combining (collage) the fundus images. In this case, it is preferable that the scanning range is divided into two around the photographing optical axis, and a fundus image is photographed in each of the two divided scanning ranges. Note that, in this case, the synthesis processing is not necessarily limited to image processing. For example, a composite image can be formed on the imaging surface by switching the projection area where the illumination light is projected at the timing when the illumination light arrives at the division position of the scanning range.

  In this case, between the two fundus images, it is preferable that the relationship between the scanning range on the fundus and the projection area where the illumination light is projected intersects between the two fundus images. For example, when the two light projecting regions are arranged side by side in the vertical direction, and the illumination light is scanned on the fundus in the vertical direction, when passing the illumination light from the upper light projecting region, the lower half of the fundus is used. When the first fundus image is photographed based on the scanning, and the illumination light is allowed to pass from the lower light projecting area, the second fundus image is photographed based on the scanning of the upper half of the fundus. A composite image may be generated. In this case, in relation to each projection area, the reflected image of the objective lens and the images obtained by photographing the portion where the artifact such as flare is hardly included are combined. Therefore, it is possible to obtain a composite image in which artifacts are suppressed.

  The following shooting control may be executed instead of the synthesis processing. That is, the projection area may be switched by the control unit at the timing when the illumination light that scans on the fundus at the time of photographing reaches the boundary position of the two divisions. A composite image in which a reflection image is suppressed is generated without requiring a composite process.

<Sixth artifact suppression processing>
In the sixth artifact suppression process, the fundus image is photographed twice (at least twice) without changing the positional relationship between the photographing optical axis and the visual axis of the subject's eye. The control unit switches the shooting conditions other than the positional relationship between the two shootings. Thereby, the first fundus image in which the artifact is suppressed, and the second fundus image in which the image quality is prioritized with respect to the first fundus image are photographed, and the region including the artifact in the second fundus image is captured. , The corresponding area in the first fundus image is synthesized. As a result, the device acquires a composite image that is a fundus image in which artifacts are suppressed.

  In the sixth artifact suppression processing, since the positional relationship between the imaging optical axis and the visual axis of the subject's eye is not changed between the two imagings, two times in a shorter time than in the second artifact suppression processing. By taking a picture, a composite image can be obtained.

  Various conditions under which there is a trade-off between the image quality and the difficulty in generating artifacts can be imaging conditions that are changed between two imagings.

  For example, the control unit may change the shooting condition regarding the diopter correction amount between two shootings. In this case, the first fundus image may be, for example, a fundus image obtained by performing the artifact suppression process in the above-described first embodiment. That is, a fundus image captured by adjusting the irradiation-side correction amount to a value different from the light-receiving-side correction amount may be used. In this case, the second fundus image may be a fundus image captured in a state where the irradiation-side correction amount and the light-receiving-side correction amount match.

  In addition, for example, the control unit may change the condition regarding the separation state of the fundus reflected light and the harmful light between two shootings. In this case, the first fundus image may be photographed under photographing conditions such that the luminance is lower than that of the second fundus image.

  For example, when photographing the first fundus image, the aperture of the stop arranged in at least one of the light projecting optical system and the light receiving optical system is reduced in comparison with the case of photographing the second fundus image. Is also good. For example, in the above-described slit scan type optical system, when the size of the light-transmitting portion (for example, the opening) in the slit forming portion is such that the first fundus image is photographed, the second fundus image is photographed. It may be reduced compared to. In addition, when the passage area of the fundus reflection light in the harmful light removing unit (for example, the diaphragm) provided in the light receiving optical system captures the first fundus image, it is compared with the case of capturing the second fundus image. May be restricted. As a result, harmful light due to reflection from the objective lens or the like is appropriately separated from fundus reflected light guided on the imaging surface. As a result, it becomes easier to obtain a fundus image in which artifacts are suppressed.

  In the case of a slit scan type optical system, one or both of the slit forming unit and the harmful light removing unit may be a variable slit. In the case of the variable slit, the width of the irradiation area, the effective area (imaging area), or both can be switched between a first width and a second width wider than the first width. In this case, one or both of the slit forming portion and the harmful light removing portion 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. May be provided.

  In this case, as shown in FIG. 13, the fundus imaging apparatus may include an optical chopper having a rotating body (for example, a wheel) as a scanning unit. In the optical chopper, a rotating body in which a plurality of slit openings are arranged side by side on one circle serves as one or both of the slit forming section and the harmful light removing section. In the optical chopper, the rotating body is driven to rotate. Thereby, the plurality of slit openings are continuously traversed with respect to the optical path of the illumination light or the return light. The shape of the rotating body may be, for example, a disk shape (wheel shape) as shown in FIG. 13 or a cylindrical shape. In a cylindrical rotating body, a plurality of slits are formed on a cylindrical side surface. The rotating body may be driven at a constant speed.

  In the example of FIG. 13, the rotating body includes a first area in which one or two or more first slit openings corresponding to a first width are continuously arranged, and a second slit opening corresponding to a second width. And a second area in which one or two or more are continuously arranged. In this case, the control unit sets the illumination area or the effective area (imaging area) 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. The width switches. The control unit acquires a fundus image obtained in the first period as a first fundus image, acquires a fundus image obtained in the second period as a second fundus image, and generates a combined image of both. Is also good.

  In the case where the illumination light is visible light, it is preferable that, of the two fundus images, the second fundus image with the image quality given priority is photographed first, and the first fundus image is photographed later. . Therefore, the control unit may execute a continuous photographing operation (continuous photographing process) of photographing two fundus images at predetermined intervals in the order of the second fundus image and the first fundus image. The predetermined interval is preferably an interval that is sufficiently short from the time (approximately several tens of seconds) from when the image is captured with visible light to when the miosis disappears.

  When two fundus images are photographed in a short time using visible light, miosis occurs, and in an image photographed later, the peripheral portion tends to be dark due to vignetting of illumination light at the pupil. On the other hand, by photographing the second fundus image prioritizing the image quality first and photographing the first fundus image later, it is easy to obtain a good fundus image up to the peripheral portion in the composite image.

  When the scanning unit is an optical chopper, the device may further include a sensor that detects a rotational position of the rotating body. The exposure of the image sensor and the sweeping of the image may be controlled based on the signal from the sensor.

<Third embodiment>
Next, a third embodiment will be described. The fundus imaging apparatus according to the third embodiment (see FIG. 14) captures a fundus image by scanning the fundus with slit-shaped illumination light. The device according to the third embodiment captures a fundus image in a state where the diaphragm is located at a position different from the fundus conjugate position. At the time of imaging, since the aperture is arranged at a position different from the fundus conjugate position, artifacts due to reflection by the objective lens can be suppressed. Note that the fundus imaging apparatus according to the third embodiment may include some of the multiple embodiments described above as the first embodiment.

  The fundus imaging apparatus according to the third embodiment has at least an imaging optical system and a diopter correction optical system. Additionally, the fundus imaging device may include a control unit.

  The imaging optical system according to the third embodiment includes an irradiation optical system, a light receiving optical system, and a scanning unit. The irradiation optical system irradiates slit-shaped illumination light to the fundus of the eye to be examined via an objective lens. The light receiving optical system shares the objective lens with the irradiation optical system. The light receiving optical system further forms an image of the fundus oculi on the imaging surface based on the fundus reflection light of the illumination light.

  The scanning unit according to the third embodiment is used for displacing one or both of a local illumination region and a local imaging region that are a part of a fundus imaging range. The scanning unit according to the third embodiment may include at least a slit and a driving unit (driver). Alternatively, the scanning unit may be a device that scans illumination light that is formed in a slit shape in advance. The stop may be arranged in one of the irradiation optical system and the light receiving optical system, or may be arranged in both. The shape of the aperture in the stop may be, for example, a slit shape (see the first and second embodiments), a circular shape, or another shape. When a device that scans illumination light formed in a slit shape in advance is used as the scanning unit, the aperture may be statically arranged with respect to the optical system.

  The diopter correction optical system corrects diopter in the photographing optical system.

  In the third embodiment, a fundus image is photographed in a state where the diaphragm is arranged at a position different from the fundus conjugate position in the above-described apparatus configuration. However, the aperture may be for removing stray light from the anterior segment. That is, the diaphragm has a non-conjugated positional relationship with both the cornea and the crystalline lens. In addition, it is preferable to dispose it near the fundus conjugate position as long as the effect of suppressing the reflection from the objective lens can be enjoyed.

  At this time, the aperture may be previously arranged, for example, at a position apart from any of the imaging surface and its conjugate position. At this time, it is preferable that the stop is disposed on the plus diopter side with respect to the conjugate position of the imaging surface. By disposing the stop in advance at a position different from any one of the imaging surface and its conjugate position, the position of the stop can be moved away from the condensing position of the reflected light at the objective lens, and artifacts can be suppressed.

  Further, when the stop is disposed at a position apart from any one of the imaging surface and its conjugate position, the diopter correction in both the irradiation optical system and the light receiving optical system is not too much or less than the refractive power of the eye to be examined. In this state, a fundus image may be taken. In this case, the diopter correction optical system always calculates the irradiation-side correction amount (the diopter correction amount in the irradiation optical system) and the light-receiving-side diopter correction amount (the diopter correction amount in the light-receiving optical system), respectively. It may not be possible to adjust independently. Therefore, the device configuration is easily simplified.

  On the other hand, the fundus imaging apparatus according to the third embodiment may have diopter correction optics similar to that of the first embodiment. In this case, the diopter correction optical system can independently adjust the irradiation-side correction amount that is the diopter correction amount in the irradiation optical system and the light-receiving-side correction amount that is the diopter correction amount in the light-receiving optical system. Is also good. The control unit may control the diopter correction optical system when capturing the fundus image, and set the irradiation-side correction amount and the light-receiving-side correction amount to values different from each other. At this time, the light-receiving-side correction amount may be a value corresponding to the refractive power of the eye to be inspected, and the irradiation-side correction amount may be a value different from a value corresponding to the refractive power of the eye to be inspected.

"Example"
Next, an example of the fundus imaging apparatus according to the first to third embodiments will be described with reference to FIGS. 1 to 4, 12, and 15.

  The fundus imaging apparatus 1 (hereinafter, simply referred to as “imaging apparatus 1”) forms illumination light in a slit shape on the fundus of the eye to be inspected, scans the slit-shaped area on the fundus, and illuminates. A front image of the fundus is captured by receiving light reflected by the fundus.

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

  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 driving unit 8 further moves the photographing unit 3 on the driving unit 8 in the three-dimensional direction with respect to the eye E to be inspected. The drive unit 8 includes an actuator for moving the drive unit 8 or the imaging unit 3 in each of the predetermined movable directions, and is driven based on a control signal from the control unit 80. The face support unit 9 supports the face of the subject. 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 the photographing unit 3 is constant. The face photographing camera 110 photographs the face of the subject. The control unit 100 specifies the position of the eye E from the captured face image and controls the driving of the driving unit 8 to align the imaging unit 3 with the specified position of the eye E.

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

<Optical System of Example>
Next, an optical system of the photographing apparatus 1 will be described with reference to FIG. The imaging device 1 includes an imaging optical system (fundus imaging optical system) 10 and an anterior ocular segment observation optical system 40. These optical systems are provided in the photographing unit 3.

  In FIG. 2, a position conjugate to the pupil of the subject's eye is indicated by “△” on the imaging optical axis, and a fundus conjugate position is indicated by “×” on the imaging optical axis.

  The photographing optical system 10 has 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 member 15a, lenses 17a and 17, a mirror 18, a perforated mirror 20, and an objective lens 22. The light receiving optical system 10b has an objective lens 22, a perforated mirror 20, lenses 25a and 25b, a slit-shaped member 15b, and an image sensor 28. The perforated mirror 20 is an optical path coupling unit 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 eye E, and allows a portion of the fundus reflection light from the eye E that has passed through the opening to pass to the image sensor. Various beam splitters other than the perforated mirror 20 can be used. For example, instead of the perforated mirror 20, a mirror in which the perforated mirror 20, the light transmitting portion, and the reflecting portion are reversed may be used as the optical path coupling portion. However, in this case, an independent optical path of the light receiving optical system 10b is provided on the reflection side of the mirror, and an independent optical path of the irradiation optical system 10a is provided on the transmission side of the mirror. Further, the perforated mirror and the mirror as an alternative means can be further replaced by a combination of a half mirror and a light shielding unit.

  In this embodiment, the light source unit 11 has a plurality of types of light sources having different wavelength bands. For example, the light source unit 11 has visible light sources 11a and 11b and infrared light sources 11c and 11d. Thus, the light source unit 11 of the present embodiment is provided with two light sources for each wavelength. Two light sources having the same wavelength are arranged 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 symmetric with respect to the imaging optical axis L. As shown in FIG. 2, the outer peripheral shape of the two light sources may be a rectangular shape in which the direction intersecting the scanning direction is longer than the scanning direction.

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

  In FIG. 2, the slit-shaped member 15a is displaced by the driving unit 15c such that the light transmitting unit crosses the photographing optical axis L in the X direction. Thereby, the scanning of the illumination light in the present embodiment is realized. In the present embodiment, scanning by the slit-shaped member 15b is also performed on the light receiving system side. In the present embodiment, the slit-shaped members 15a and 15b on the light emitting side and the light receiving side are driven by one driving unit (actuator) in conjunction with each other. In this embodiment, a scanning unit is realized by the slit members 15a and 15b and a driving unit (not shown).

  In the irradiation optical system 10a, the image of each light source is relayed by the optical system from the lens 13 to the objective lens 22, and is formed 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. Thus, in the present embodiment, the two light projection areas P1 and P2 on the pupil conjugate plane are formed as images of the two light sources.

  The slit-shaped light passing through the slit-shaped member 15a is relayed by an optical system from the lens 17a to the objective lens 22, and forms an image on the fundus Er. Thereby, the illumination light is formed in a slit shape on the fundus Er. The illumination light is reflected on the fundus Er and is extracted from the pupil Ep.

  Here, since the aperture of the perforated mirror 20 is conjugate with the pupil of the eye to be inspected, the fundus reflection light used for photographing the fundus image passes through the image of the aperture of the perforated mirror (pupil image) on the pupil of the eye to be inspected. You are limited to some. Thus, the image of the opening on the pupil of the subject's eye becomes the light receiving region R in the present embodiment. The light receiving region R is formed between two light projecting regions P1 and P2 (images of two light sources). Further, 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 region R and the two light projecting regions P1 and P2 do not overlap each other on the pupil. Formed. Thereby, the occurrence of flare is favorably reduced.

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

  The image sensor 28 is arranged at a fundus conjugate position. In the present embodiment, the relay system 27 is provided between the slit-shaped member 15b and the image sensor 28, whereby both the slit-shaped member 15b and the image sensor 28 are arranged at the fundus conjugate position. As a result, both the removal of the harmful light and the imaging are performed favorably. Instead of this, the relay system 27 between the imaging element 28 and the slit-shaped member 15b may be omitted, and both may be arranged close to each other. In this embodiment, a device having a two-dimensional light receiving area is used as the image sensor 28. For example, a CMOS or a two-dimensional CCD may be used. The image of the slit-shaped region of the fundus Er, which is formed by the light-transmitting portion of the slit-shaped member 15b, is projected on the image sensor 28. The image sensor 28 has sensitivity to both infrared light and visible light.

  In this embodiment, as the slit-shaped illumination light is scanned on 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. Thus, the entire image of the scanning range is projected on the image sensor in a time-division manner. As a result, a front image of the fundus Er is captured as an entire image of the scanning range.

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

  The imaging optical system 10 has a diopter correction unit. In the present embodiment, a diopter correction unit (diopter correction optical systems 17 and 25) is 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 is referred to as an irradiation-side diopter correction optical system 17, and the light-receiving-side diopter correction optical system is referred to as a 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 unit 17c (see FIG. 3). Further, the light-receiving-side diopter correction optical system 25 of the present embodiment includes a lens 25a, a lens 25b, and a drive unit 25c (see FIG. 3). In the irradiation-side diopter correction optical system 17, the distance between the lens 17a and the lens 17b is changed, and in the light-receiving diopter correction optical system 25, the distance between the lens 25a and the lens 25b is changed. Thereby, diopter correction is performed in each of the irradiation optical system 10a and the light receiving optical system 10b.

  The driving unit 17c of the irradiation optical system 10a and the driving unit 25c of the light receiving optical system 10b can be driven independently. As a result, in the present embodiment, as shown in FIG. 4B, the irradiation-side correction amount that is the diopter correction amount in the irradiation optical system 10a and the light-receiving-side correction amount that is the diopter correction amount in the light-receiving optical system 10b are: Each can be set independently.

  In this embodiment, each of the irradiation-side diopter correction optical system 17 and the light-receiving-side diopter correction optical system 25 includes a telecentric optical system. Each telecentric optical system maintains the image height in the image-side area even if the diopter correction amount changes. Thus, the positional relationship between the slit opening of the irradiation optical system and the slit opening of the light receiving optical system on the fundus can be kept constant regardless of the balance between the irradiation-side correction amount and the light-receiving-side correction amount. For this reason, the slit opening of the irradiation optical system and the slit opening of the light receiving optical system on the fundus can always be matched regardless of the balance between the irradiation-side correction amount and the light-receiving-side correction amount. Further, it is possible to suppress a change in image size according to a change in the diopter correction amount.

  As shown in FIG. 2, the imaging optical system 10 further includes a split target projection optical system 50 as an example of a focus target projection optical system. The split target projection optical system 50 projects two split targets on the fundus. The split index is used for detecting a focus state. In this embodiment, the refractive power of the eye E 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 the present 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 members 15a and 15b is arranged at a corresponding position. Specifically, when the diopter correction amounts on the irradiation side and the light receiving side are 0D, the optotype plate 52 is arranged at a position substantially conjugate with the fundus of the normal eye (0D eye). The deflection prism 53 is disposed closer to the index plate 52 on the side of the subject's eye than the index plate 52.

  The index plate 52 is formed using, for example, slit light as an index. The deflection prism 53 separates the index light beam passing 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 and the objective lens 22. For this reason, the split index is reflected in a fundus image (for example, a fundus observation image).

  When the index plate 52 is displaced from the fundus conjugate position, the two split indices are separated on the fundus, and when the index plate 52 is located at the fundus conjugate position, the two split indices match. 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 the present embodiment, defocusing is performed while making the irradiation-side diopter correction amount and the light-receiving-side diopter correction amount coincide with each other. At this time, the split state of the split index indicates the focus state. By adjusting the diopter correction amounts on the irradiation side and the light receiving side so that the two split indices are matched, each of the imaging surface and the slit-shaped members 15a and 15b has a positional relationship conjugate with the fundus. Become.

  The refractive power of the eye E can be derived from the diopter correction amount when each of the imaging surface and the slit members 15a and 15b has a conjugate positional relationship with the fundus. Therefore, in the present embodiment, an encoder (not shown) for reading any one of the interval between the lens 17a and the lens 17b or the interval between the lens 25a and the lens 25b may be further provided. The refractive power of the eye E may be acquired on the basis of the signal from.

  The scanning unit may be, for example, an optical chopper as shown in FIG. The optical chopper has a wheel having a plurality of slits formed on the outer periphery, and can rotate the wheel to scan the slits at high speed.

  Here, in FIG. 2, the components from the light source unit 11 of the irradiation optical system 10a to the mirror 18 and the components of the light-receiving optical system 10b from the perforated mirror 20 to the image sensor 28 are arranged in parallel in the X direction. By rotating the directions of the opening mirror 20 and the mirror 18 by 90 degrees from the state shown in the figure and arranging them in parallel in the Y direction, the optical chopper can be used as a scanning unit. In this case, as shown in FIG. 12, the optical axis of the irradiation optical system 10a and the optical axis of the light receiving optical system 10b are respectively traversed at two positions, that is, the upper end and the lower end of the wheel. The scanning of the light projecting system and the light receiving system can be easily synchronized.

<Anterior eye observation optical system>
Next, the anterior ocular segment observation optical system 40 will be described. The anterior ocular segment observation optical system 40 shares the objective lens 22 and the dichroic mirror 43 with the imaging optical system 10. The anterior ocular 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 front image of the anterior segment.

  Note that the anterior ocular segment observation optical system 40 illustrated in FIG. 2 is merely an example, and the anterior ocular segment may be imaged using an optical path independent of other optical systems.

<Control system of embodiment>
Next, a control system of the photographing apparatus 1 will be described with reference to FIG. In this embodiment, the control unit 100 controls each unit of the image capturing apparatus 1. For convenience, the image processing of various images obtained by the photographing apparatus 1 is also performed by the control unit 100. In other words, in the present embodiment, the control unit 100 also serves as the image processing unit.

  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 realized 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, the storage unit 101 may store temporary data and the like.

  The image captured by the image capturing apparatus 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).

  The control unit 100 includes the driving unit 8, the light sources 11a to 11d, the driving unit 15c, the driving unit 17c, the driving unit 25c, the imaging device 28, the light source 41, the imaging device 47, the light source 51, the input interface 110, the monitor 120, and the like. Are electrically connected to each other.

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

<Description of operation of the embodiment>
Next, the photographing operation will be described based on the flowchart of FIG.

  The image capturing apparatus 1 may automatically start an image capturing operation when the face of the subject is placed on the face supporting unit 9 and included in the image capturing range of the face detection camera 110.

  First, photographing by the face detection camera 110 and the anterior ocular segment observation optical system 40 is performed in parallel (S1), and alignment adjustment using the photographing results of both is performed (S2).

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

  Next, an alignment reference position is set based on the anterior ocular segment front image, and alignment is guided to the set alignment reference position. In the present embodiment, the positional relationship between the subject's eye E and the imaging unit 3 is adjusted by the control unit 100 based on the anterior segment front image. In the present embodiment, based on the signal from the image sensor 47, the control unit 100 determines the position where the center of the pupil in the anterior ocular segment observation image and the image center (in this embodiment, the position of the photographing optical axis L) substantially match. A first reference position targeting a relationship is set. Then, an alignment shift from the first reference position is detected, and the photographing unit 4 is moved in the up, down, left, and right directions in a direction in which the alignment shift is eliminated. At this time, for example, the misalignment between the first reference position and the pupil center on the anterior ocular segment observation image may be detected based on the amount of deviation between the pupil center and the imaging optical axis. In addition, when the fundus imaging apparatus 1 has, for example, an alignment projection optical system that projects an alignment index onto a cornea vertex, an alignment shift may be detected based on a deviation amount between the alignment index and the imaging optical axis. .

  The control unit 100 also moves the photographing unit 4 in the front-back direction so that the anterior eye observation image is focused on the pupil Ep. Thereby, the distance from the apparatus to the subject's eye is adjusted to a predetermined working distance.

  As described above, in the present embodiment, as a result of the alignment adjustment in S2, the positional relationship between the subject's eye and the photographing unit 4 is such that the center of the light receiving region R on the pupil of the subject's eye (that is, the photographing optical axis) is the pupil center. (The first reference position in the present embodiment).

  After the first shooting mode is set, the control unit 100 starts shooting and displaying a fundus oculi observation image (S3). More specifically, the control unit 100 simultaneously turns on the light sources 11c and 11d and starts driving the driving unit 15c, so that the slit-shaped illumination light is repeatedly scanned in a predetermined range on the fundus Er. At every predetermined number of scans (at least once), a fundus image captured substantially in real time is generated as a fundus observation image at any time based on a signal output from the image sensor 28. The control unit 100 may cause the monitor 120 to display the fundus oculi observation image as a substantially real-time moving image.

  Next, the focus state in the irradiation optical system and the light receiving optical system is adjusted based on the fundus observation image (S4). In this embodiment, after the alignment is completed, the diopter correction optical system is driven to perform focus adjustment. 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 processing, first, the control unit 100 starts projection of the split index on the fundus by turning on the light source 51. The control unit 100 performs defocusing by changing the correction amount while making the irradiation-side diopter correction amount and the light-receiving-side diopter correction amount coincide. Further, every time the correction amount changes, the control unit 100 detects the split state of the split index from the fundus observation image, and determines the irradiation-side diopter correction amount and the light-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-shaped members 15a and 15b have a conjugate positional relationship with the fundus.

  Further, in the present embodiment, the diopter correction amount when the split index matches is acquired by the control unit 100 as refractive power information (S5).

  Next, the control unit 100 sets the shooting mode based on the refractive power information. First, the diopter correction amount, which is refractive power information, is compared with a predetermined threshold (S6). In this embodiment, assuming that an artifact occurs when each of the irradiation-side correction amount and the light-receiving-side correction amount is on the minus diopter side with respect to −12D, “−12D” is set as the threshold of the refractive power. Has been adopted. In other words, the first range indicated by reference numeral A1 in FIG. 4B is a range on the plus diopter side from "-12D" in the present embodiment. The second range indicated by reference numeral A2 is “−12D” in the present embodiment, and is a range on the minus diopter side. However, the range of the diopter in which an artifact due to the reflection of the objective lens 22 is different depending on the optical design of the device, a value according to the optical design of the device may be used as the threshold.

  In the present embodiment, if the refractive power of the subject's eye is a value on the plus diopter side from "-12D", the first photographing mode is set (S6: No). On the other hand, if the refractive power of the subject's eye is “−12D” or a value on the negative diopter side, the second imaging mode is set (S6: Yes). The first shooting mode is an invalid mode in the embodiment, and the second shooting mode is an effective mode in the embodiment.

  In the first shooting mode, the process proceeds to S8, where shooting conditions other than the diopter correction amount are adjusted according to the shooting mode (S8). After the adjustment, a fundus image is captured (S9). At this time, the light emission from the observation light sources 11c and 11d may be stopped, and then the imaging light sources 11a and 11b may be turned on. In this case, a photographed image of the fundus is obtained as a photographing result based on the visible light emitted from the light sources 11a and 11b.

  In the present embodiment, in the first imaging mode, a fundus image is imaged in a state where the irradiation-side correction amount and the light-receiving-side correction amount match each other (see FIG. 4A). At the time of photographing, the irradiation-side correction amount and the light-receiving-side correction amount are values immediately after adjustment in the focus adjustment processing (S5). Therefore, the diopter correction amount is in a range where the artifact is not a problem, and the fundus is photographed in a state where each of the imaging surface and each of the slit-shaped members 15a and 15b has a conjugate positional relationship with the fundus. Therefore, a good fundus image is captured.

  On the other hand, in the second imaging mode, the irradiation-side correction amount is shifted to the plus diopter side with respect to the value when the split index matches (see FIG. 4B). As a result, the focus position of the illumination light moves away from the objective lens, so that artifacts due to the reflection of the objective lens 22 are less likely to occur. In this embodiment, the value of the irradiation-side correction amount after the transition may be a fixed value, or may vary according to the light-receiving-side correction amount in a range that does not match the light-receiving-side correction amount. In this embodiment, the irradiation-side correction amount is shifted to “−10D” which is a value on the plus diopter side from the threshold. However, the present invention is not necessarily limited to this, and may be shifted to a threshold.

  Next, shooting conditions other than the diopter correction amount are adjusted according to the second shooting mode. At this time, since the diopter correction amount in the irradiation optical system is deviated from the best focus, the slit light irradiated as the illumination light is blurred on the fundus. As a result, the fundus reflection light passing through the opening of the slit 15b in the light receiving optical system is reduced, so that the received light amount is reduced.

  Therefore, the control unit 100 sets one of the amount of illumination light output from the light sources 11a and 11b or the light sources 11c and 11d, the gain of the Increase in the shooting mode. This suppresses a decrease in image quality due to the fact that slit light emitted as illumination light is blurred on the fundus as a result of the processing in S7.

  Then, the control unit 100 captures a fundus image after adjusting the capturing conditions (S9). In the second imaging mode, a fundus image is captured in a state where the irradiation-side correction amount and the light-receiving-side correction amount do not match. As a result, in the present embodiment, even when a myopic eye is photographed, the occurrence of artifacts is suppressed. At the time of shooting, the diopter correction amount in the light receiving optical system 10b is a value immediately after adjustment in the focus adjustment processing (S5). Therefore, since the fundus and the imaging surface are conjugate, out-of-focus in the fundus image is suppressed. Further, in the second imaging mode, the slit 15a is arranged in a non-conjugated positional relationship with the fundus Er, so that the slit light irradiated as illumination light is blurred on the fundus. However, any one of the imaging conditions among the light intensity of the illumination light, the gain of the imaging element 28, and the exposure time is increased compared to the first imaging mode, so that a fundus image having an appropriate dynamic range is easily obtained.

  In the method of suppressing an artifact on a fundus image by image processing, a trace of the image processing may be left in the image. On the other hand, in the present embodiment, image processing for suppressing artifacts is not necessarily required, and thus in the fundus image, the tissue of the fundus is more naturally depicted.

  Further, in the second imaging mode, it is considered that the burden on the subject is increased as compared with the first imaging mode by increasing the illumination light amount or the exposure time. However, since the time from the start of shooting (start of irradiation of illumination light for shooting) to completion is relatively short, the increase in the burden is considered to be relatively small. Therefore, even when imaging the eye to be examined having a high degree of myopia, a fundus image in which artifacts are suppressed can be imaged without imposing a large burden on the subject.

<Second embodiment>
Next, a second example of the fundus imaging apparatus according to the third embodiment will be described with reference to FIG. Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment. 14, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted unless otherwise specified. In FIG. 14, the illustration of the anterior ocular segment observation optical system 40 and the split target projection optical system 50 is omitted from the optical system of the first embodiment shown in FIG.

  FIG. 14 illustrates an optical system of the fundus imaging apparatus 1 according to the second example. The fundus imaging apparatus 1 according to the second embodiment is different from the first embodiment in the position of the slit-shaped member (an example of the diaphragm). Specifically, in the first embodiment, the slit members 15a and 15b are arranged at conjugate positions with the imaging surface. On the other hand, as shown in FIG. 14, the slit members 150a and 150b in the second embodiment are arranged in advance at a position different from the conjugate position on the imaging surface. In FIG. 14, both the slit-shaped member 150a arranged in the irradiation optical system 10a and the slit-shaped member 150b arranged in the light receiving optical system 10b are arranged at positions different from the conjugate positions on the imaging surface. ing. Each of the two slit-like members 150a and 150b is disposed on the plus diopter side with respect to the conjugate position of the imaging surface. Thereby, the interval between the condensing position of the reflected light of the objective lens and the openings in the two slit members 150a and 150b is secured. As a result, even if the diopter correction in each of the irradiation optical system and the light receiving optical system is appropriately performed (without excess or deficiency with respect to the refractive power of the eye to be inspected), the generation of the artifact based on the reflected light of the objective lens is suppressed. . In addition, as compared with the first embodiment, it is easier to adjust the diopter correction amount in a short time when photographing. However, the present invention is not necessarily limited to this, and one of the two slit members 150a and 150b may be arranged at a conjugate position on the imaging surface.

<Transformation example>
As described above, the description has been given based on the embodiment. However, in implementing the present disclosure, the content of the embodiment can be appropriately changed.

<Switching control according to pupil size>
In the first embodiment, the difference value between the irradiation-side correction amount and the light-receiving-side correction amount is adjusted by the control unit 100 in accordance with the refractive power of the eye to be inspected. The difference value at this time may further consider the size of the pupil. Further, the difference value may be adjusted in conjunction with a control operation set for each pupil size.

  As an example, in the example shown in FIG. 5, the control of the apparatus is performed in a total of four cases (case 1) in accordance with the pupil size (here, the pupil diameter) and the diopter value (refractive power) of the eye to be examined. To Case 4). In other words, one of the four shooting modes is selected according to the pupil size and the diopter value. For example, the shooting mode may be selected based on the size of the pupil detected from the front image of the anterior eye part.

  In the example shown in FIG. 5, (1) the clearance between the light projecting area P and the light receiving area R, (2) the alignment reference position in the X and Y directions, and (3) the difference between the irradiation side correction amount and the light receiving side correction amount. The three persons are changed by the control unit 100 according to the size of the pupil (here, the pupil diameter) and the diopter value (refraction power) of the eye to be examined. Each condition is adjusted according to the comparison result of the size of the pupil (here, the pupil diameter) and the diopter value (refractive power) of the eye to be examined with respect to respective threshold values. As an example, “−12D” is used as the threshold value of the refractive power. “4 mm” is used as the threshold value of the pupil diameter. Any of the thresholds is merely an example, and may be appropriately changed.

  In order to change the clearance between the light projecting area P and the light receiving area R, a pair of second light sources may be provided between the light sources 11a and 11b and the optical axis L. In this case, the clearance may be changed by switching the light source to be turned on. Alternatively, the distance between the light sources 11a and 11b with respect to the optical axis L may be changeable. In the present embodiment, the clearance is changed between a predetermined first interval and a second interval. Note that the second interval is narrower than the first interval.

  In the embodiment, the alignment reference position is switched between the first reference position and the second reference position. The first reference position is a position where the center of the light receiving region R and the corneal vertex (or the pupil center) match. The second reference position is a position where the positional relationship between the center of the light receiving region R and the corneal vertex (or the pupil center) is shifted by a predetermined distance from the first reference position.

  The control unit 100 guides the alignment based on the alignment deviation from the alignment reference position. Here, the alignment may be guided by a so-called automatic alignment method or a manual alignment method. In the auto alignment method, the control unit 100 may control the driving of the driving unit based on the alignment deviation from the alignment reference position.

<Case 1 (example of invalid mode)>
In Case 1, the pupil diameter is larger than the threshold and the refractive power is on the plus diopter side of the threshold. In this case, each condition is set as follows.
(1) Clearance between the light projecting area P and the light receiving area R: first interval (2) Alignment reference position in XY directions: first reference position (3) Difference value d between irradiation-side correction amount and light-receiving side correction amount: 0D
In case 1, artifacts due to reflection at the objective lens are unlikely to occur, so that the artifact suppression processing need not be performed. Further, since the pupil diameter is sufficiently large, a good fundus image can be taken without narrowing the clearance between the light projecting region P and the light receiving region R or shifting the alignment reference position in the XY directions.

<Case 2 (example of valid mode)>
In case 2, the pupil diameter is larger than the threshold and the dioptric power is on the minus diopter side of the threshold. In this case, each condition is set as follows.
(1) Clearance between the light projecting area P and the light receiving area R: first interval (2) Alignment reference position in XY directions: first reference position (3) Difference value d between irradiation-side correction amount and light-receiving side correction amount: 5D
In case 2, since the refractive power is on the minus diopter side of the threshold value, artifacts are more likely to occur than in case 1. Therefore, control is performed so that the irradiation-side correction amount and the light-receiving-side correction amount have different values. As a result, artifacts can be suppressed. Further, since the pupil diameter is sufficiently large, there is no need to narrow the clearance between the light projecting region P and the light receiving region R or to shift the alignment reference position in the XY directions.

<Case 3 (Example of valid mode)>
In Case 3, the pupil diameter is smaller than the threshold value, and the refractive power is on the plus diopter side of the threshold value. In this case, each condition is set as follows.
(1) Clearance between light projecting area P and light receiving area R: second interval (2) Alignment reference position in XY directions: second reference position (3) Difference value d between irradiation-side correction amount and light-receiving side correction amount: 2.5D
In Case 3, since the pupil diameter is smaller than the threshold, the clearance between the light projecting area P and the light receiving area R is narrowed, and the alignment reference position in the XY directions is shifted with respect to the first reference position. In the present embodiment, artifacts are likely to occur due to these controls. Thus, by setting the irradiation-side correction amount and the light-receiving-side correction amount to values different from each other, artifacts are suppressed. That is, a larger value is given as the difference value d than in the case 1. Note that the value of the difference value d in Case 3 is smaller than the difference value d in Case 2, but is not necessarily limited thereto. The value of the difference value d in each case may be appropriately set for each optical system.

<Case 4 (example of valid mode)>
In Case 4, the pupil diameter is smaller than the threshold, and the refractive power is on the minus diopter side of the threshold. In this case, each condition is set as follows.
(1) Clearance between light projecting area P and light receiving area R: second interval (2) Alignment reference position in XY directions: second reference position (3) Difference value d between irradiation-side correction amount and light-receiving side correction amount: 5D
In Case 4, since the pupil diameter is smaller than the threshold, the clearance between the light projecting area P and the light receiving area R is narrowed, and the alignment reference position in the XY directions is shifted with respect to the first reference position. The same value as in Case 2 is used as the difference value d between the irradiation-side correction amount and the light-receiving-side correction amount. However, when the above-described control according to the pupil diameter makes the artifact more likely to occur, a larger value than in Case 2 may be set as the difference value d.

<Transformation example of diopter correction optical system>
For example, in each embodiment, as the diopter correction optical systems 17 and 25, an optical system in which a diopter correction amount is set according to a lens interval is shown as an example. However, the diopter correction optical system is not necessarily limited to this, and various optical systems can be adopted. For example, in the case of the optical system shown in FIG. 2, the diopter correction in the irradiation optical system 10a becomes possible by displacing the slit-shaped member 15a in the optical axis direction instead of the lens 17a. When the slit-shaped member 15a is displaced in the optical axis direction, the position of the condensing point K is displaced in the optical axis direction. Similarly, by displacing the slit-shaped member 15b in the optical axis direction instead of the lens 25b, diopter correction in the light receiving optical system 10b becomes possible. In this case, the lens 27 and the image sensor 28 may also be moved in conjunction with the slit member 25b. Further, in this case, it is difficult for one driving unit to perform scanning by the slit-shaped member 15a and scanning by the slit-shaped member 15b, so that the slit-shaped members 15a and 15b , May each have a drive unit.

<Shooting control during fluorescent shooting>
Further, for example, in each of the above embodiments, the fundus imaging apparatus not only captures a fundus image based on the fundus reflected light, but also captures a fluorescent fundus image that is a fundus image based on fluorescence emitted from the fundus. Good.

  In this case, illumination light is emitted from the irradiation optical system as excitation light. The wavelength range of the illumination light can be appropriately set according to the intended fluorescent substance. The fluorescent substance may be a contrast agent (for example, indocyanine green and fluorescein) or a spontaneous fluorescent substance (for example, lipofuscin) accumulated in the fundus.

  In the light receiving optical system, fluorescence from the fundus based on the excitation light is guided to the light receiving element. When fluorescence imaging is performed, a barrier filter is arranged on an independent optical path of the light receiving optical system. The barrier filter has spectral characteristics such that light in the same wavelength range as the excitation light is blocked and fluorescence is transmitted. As a result, of the fundus reflection light of the excitation light and the fluorescence from the fundus, the fluorescence is selectively received by the light receiving element. As a result, a fundus fluorescent image can be favorably obtained. The fundus imaging apparatus may include a driving unit for inserting and removing the barrier filter. The insertion and removal of the barrier filter may be controlled by the control unit.

  The control unit may switch the shooting mode between the normal shooting mode and the fluorescence shooting mode. The normal photographing mode is set to photograph a fundus image based on the fundus reflection light. The fluorescent imaging mode is set to capture a fluorescent fundus image. The control unit may control insertion / removal of the barrier filter according to the shooting mode. In this case, the control unit retracts the barrier filter in the normal shooting mode. Further, the control unit causes the barrier filter to be inserted in the fluorescence imaging mode. Here, in the fluorescent imaging mode, not only the fundus reflection light of the excitation light but also the reflection light by the objective lens is blocked by the barrier filter. Therefore, it is not necessary to execute the various artifact suppression processes described in the above embodiment in the fluorescence imaging mode. Therefore, in the fluorescence imaging mode, the artifact suppression processing need not be performed by the control unit regardless of the refractive power of the eye to be inspected. For example, in a device that suppresses the occurrence of artifacts by making the diopter correction amount (irradiation-side correction amount) in the irradiation optical system and the diopter correction amount (light-receiving-side correction amount) in the light receiving optical system inconsistent. In the fluorescence imaging mode, each value is adjusted according to the refractive power so that the irradiation-side correction amount and the light-receiving-side correction amount match.

  The present disclosure relates to <fundus imaging devices A1 to A9>, <fundus imaging devices B1 to B5>, <fundus imaging devices C1 to C18>, <fundus imaging devices D1 to D5>, and <fundus imaging devices E1 to E8>. At least. The components in each embodiment can be introduced as appropriate for another embodiment.

<Fundus imaging devices A1 to A9>
(1) Fundus imaging device A1:
An irradiation optical system that irradiates the fundus of the subject's eye with illumination light via an objective lens, and a light receiving element that shares the objective lens with the irradiation optical system and further includes a light receiving element that receives fundus reflection light of the illumination light An optical system, comprising: a photographing optical system including: a fundus photographing apparatus that acquires a fundus image based on a signal from the light receiving element, wherein a refractive power that acquires refractive power information that is information on a refractive power of the eye to be inspected. An information acquisition unit, and control means for performing an artifact suppression process for suppressing the occurrence of an artifact based on the reflection of the illumination light by the objective lens,
The control means, based on the refraction power, between the invalid mode that does not execute the artifact suppression process when photographing the fundus image, and the effective mode that executes the artifact suppression process when photographing the fundus image. To switch.

  (2) Fundus photographing apparatus A2: In the fundus photographing apparatus A1, the refractive power of the eye to be examined is roughly divided into a first range and a second range on the minus diopter side with respect to the first range, The control means switches to the invalid mode when the refractive power of the subject's eye is in the first range, and switches to the valid mode when the refractive power of the subject's eye is in the second range.

  (3) Fundus photographing apparatus A3: In fundus photographing apparatus A1 or A2, the irradiation optical system emits illumination light to the fundus as excitation light, thereby generating fluorescence from a fluorescent substance present in the fundus. In the light receiving optical system, a barrier filter that blocks the illumination light and allows the fluorescence to pass therethrough is disposed on the independent optical path of the light receiving optical system so as to be freely inserted and removed, and the control unit controls insertion and removal of the barrier filter. In addition, when the barrier filter is inserted on the independent optical path, the photographing mode is set to the invalid mode regardless of the refractive power.

  (4) Fundus photographing apparatus A4: In any one of fundus photographing apparatuses A1 to A3, in the valid mode, the control unit performs the artifact suppression processing as a plurality of pieces of images having different positions of the artifact with respect to the tissue of the eye to be inspected. , And a composite image is generated by combining the plurality of fundus images.

  (5) Fundus photographing apparatus A5: In any one of fundus photographing apparatuses A1 to A4, the photographing optical system includes a slit forming section that forms illumination light in a slit shape on the fundus of the eye to be inspected, and a slit shape on the fundus. A scanning unit that scans the formed illumination light in a direction intersecting the slit, and a light projection area through which the illumination light passes on the pupil of the eye to be examined, two light sources that are separated from each other with respect to the scanning direction of the illumination light. And a light-receiving area from which the fundus reflected light of the illumination light is extracted on the pupil of the eye to be examined is formed so as to be sandwiched between the two light-projecting areas, A fundus image is taken based on the fundus reflection light extracted from the light receiving area.

  (6) Fundus photographing device A6: In the fundus photographing device A5, in the valid mode, the control unit performs the artifact suppression processing based on the illumination light projected from one of the two light projecting regions. A first fundus image that is a fundus image, and a second fundus image that is a fundus image based on the illumination light projected from the other of the two light projection areas, and the first fundus image and the A composite image is generated using at least two of the second fundus image.

  (7) Fundus imaging apparatus A7: In the fundus imaging apparatus A5, in the invalidation mode, the control unit captures a fundus image based on the illumination light simultaneously projected from both of the two projection areas, In the valid mode, as the artifact suppression processing, whether or not to pass the illumination light is individually set for the two light projecting areas, and light is selectively projected from any of the two light projecting areas. The fundus image is photographed based on the illumination light.

  (8) Fundus photographing apparatus A8: In the fundus photographing apparatus A4, the positional relationship between the optical axis of the photographing optical system and the visual axis of the eye to be examined is changed, and The apparatus further includes a position adjustment unit for adjusting a position of an artifact, wherein the control unit captures the plurality of fundus images by changing the positional relationship for each capture in the effective mode.

  (9) Fundus photographing device A9: In any one of fundus photographing devices A1 to A3, the irradiation side correction amount which is the diopter correction amount in the irradiation optical system and the light receiving side correction amount which is the diopter correction amount in the light receiving optical system. And has a diopter correction optical system that adjusts each independently, and in the invalidation mode, the control unit shoots the fundus image by matching the irradiation side correction amount and the light receiving side correction amount, In the effective mode, the fundus image is photographed with the irradiation-side correction amount and the light-receiving-side correction amount being different from each other.

<Fundus imaging devices B1 to B5>
(10) Fundus photographing apparatus B1: an irradiation optical system that irradiates a slit-shaped illumination light to the fundus of the eye to be inspected via an objective lens, the illumination optical system shares the objective lens, and further, a fundus reflection of the illumination light A light receiving optical system having an imaging surface on which a fundus image based on light is formed, and a photographing optical system including a scanning unit; a diopter correction optical system for correcting diopter in the photographing optical system; and the objective lens And a fundus photographing apparatus for photographing a fundus image in a state where a diaphragm is arranged at a position different from a fundus conjugate position relating to both of the diopter correction optical system.
(11) Fundus imaging apparatus B2: In the fundus imaging apparatus B1, the aperture is previously arranged at a position different from any of the imaging surface and a conjugate position of the imaging surface.
(12) Fundus photographing apparatus B3: In the fundus photographing apparatus B2, the aperture is previously arranged at a position away from the conjugate position of the imaging plane toward the plus diopter.

  (13) Fundus photographing apparatus B4: In fundus photographing apparatus B2 or B3, the control means controls the diopter correction optical system when photographing the fundus image, and the imaging surface of the eye to be examined Adjust so that it is located at the fundus conjugate position.

  (14) Fundus photographing apparatus B5: In the fundus photographing apparatus B1, the diopter correction optical system includes an irradiation-side correction amount that is a diopter correction amount in the irradiation optical system and a light reception that is a diopter correction amount in the light-receiving optical system. And the side correction amount can be adjusted independently of each other, and the control unit controls the diopter correction optical system when capturing the fundus image, and adjusts the irradiation side correction amount and the light receiving side correction amount. Are set to different values from each other.

<Fundus imaging devices C1 to C18>
(15) Fundus photographing apparatus C1: an irradiation optical system that irradiates the fundus of the subject's eye with illumination light via an objective lens, and the objective lens is used in common with the irradiation optical system. A light receiving optical system having a light receiving element for receiving light, a fundus photographing apparatus that acquires a fundus image based on a signal from the light receiving element, wherein an irradiation side correction that is a diopter correction amount in the irradiation optical system And a diopter correction optical system that independently adjusts a light amount and a light-receiving side correction amount that is a diopter correction amount in the light-receiving optical system, and controls the diopter correction optical system to control the irradiation-side correction amount and the light receiving amount. Control means for setting the side correction amount to different values from each other.

  (16) Fundus photographing apparatus C2: In fundus photographing apparatus B5 or C1, the control means adjusts the light-receiving-side correction amount according to the refractive power of the eye to be inspected and via the diopter correction optical system. The irradiation-side correction amount is set such that a condensing position of the illumination light is located at a position further away from the objective lens with respect to an intermediate image plane of a fundus formed through the objective lens.

  (17) Fundus photographing apparatus C3: In fundus photographing apparatus B5 or C2, the control unit adjusts the light-receiving-side correction amount according to the refractive power of the eye to be examined, and adjusts the irradiation-side correction amount to the light-receiving side. Set a smaller absolute value for the correction amount.

  (18) Fundus photographing apparatus C4: In any one of fundus photographing apparatus B5 or C1 to C3, the control unit may determine a first photographing mode and a difference value between the irradiation-side correction amount and the light-receiving-side correction amount. The photographing mode is switched according to the refractive power of the subject's eye between a first photographing mode and a second photographing mode in which the fundus image is photographed by adjusting to a larger value than the first photographing mode.

  (19) Fundus imaging apparatus C5: In the fundus imaging apparatus C4, the control unit adjusts the difference value in consideration of the size of the pupil of the eye to be examined.

(20) Fundus photographing apparatus C6: In the fundus photographing apparatus C4 or C5, in the first photographing mode, the control unit matches the irradiation-side correction amount and the light-receiving side correction amount to obtain the fundus image. In the second photographing mode, the fundus image is photographed with the irradiation-side correction amount and the light-receiving-side correction amount being different from each other.
(21) Fundus photographing apparatus C7: In any one of fundus photographing apparatuses C4 to C6, the refractive power of the subject's eye is a first range and a second range on the minus diopter side with respect to the first range. When the refractive power of the subject's eye is in the first range, the control unit switches to the first photographing mode, and when the refractive power of the subject's eye is in the second range, 2. Switch to shooting mode.

  (22) Fundus photographing apparatus C8: any one of fundus photographing apparatuses C2 to C7, including a refractive power information acquiring unit that acquires refractive power information regarding the refractive power of the eye to be inspected, and wherein the control unit includes: The irradiation-side correction amount and the light-receiving-side correction amount are set based on this.

  (23) Fundus imaging apparatus C9: In the fundus imaging apparatus C8, the refractive power information acquisition unit detects a focus state in the light receiving optical system, and acquires the refractive power information based on the detection result of the focus state.

(24) Fundus photographing apparatus C10: In fundus photographing apparatus B5 or any of C1 to C9,
An optical path coupling unit disposed between the objective lens and the light receiving element, for coupling an optical path of the irradiation optical system and an optical path of the light receiving optical system, wherein the diopter correction optical system includes the irradiation optical system; And a first diopter correction optical system disposed on one optical path of the light receiving optical system, and on the other optical path for the one, or on a common optical path of the irradiation optical system and the light receiving optical system. A second diopter correction optical system disposed, wherein the control means controls the first diopter correction optical system and the second diopter correction optical system individually, thereby providing the irradiation. The side correction amount and the light receiving side correction amount are set to different values.

  (25) Fundus photographing apparatus C11: In fundus photographing apparatus C10, a first driving unit that drives at least one optical element included in the first diopter correction optical system, and is included in the second diopter correction optical system. A second driving unit that drives at least one optical element, wherein the control unit controls the first driving unit and the second driving unit independently.

  (26) Fundus photographing apparatus C12: In any one of fundus photographing apparatuses C1 to C11, the irradiation optical system forms a local illumination region in a part of a photographing range in the fundus, and the irradiation optical system forms a local illumination region between the fundus photographing apparatus C1 and the objective lens. The diopter correction optical system is disposed on the optical path of the light receiving optical system with the fundus reflection light from a local imaging region that is a part of the imaging range received by the light receiving element and the imaging is performed. A harmful light removing unit for removing light from a region other than the region; and a scanning unit that scans the local illumination region and the local imaging region on the fundus in synchronization with each other.

  (27) Fundus photographing apparatus C13: In the fundus photographing apparatus B5 or C12, the harmful light elimination unit may be configured to include at least the objective lens and The diopter correction optical system is arranged at a position conjugate with the fundus.

  (28) Fundus photographing apparatus C14: In any one of fundus photographing apparatuses B5 and C12 to C13, the diopter correction optical system includes the irradiation side correction amount and the irradiation side correction amount in each of the irradiation optical system and the light receiving optical system. It includes a telecentric optical system that maintains the image height on the image side regardless of the combination with the light-receiving-side correction amount.

  (29) Fundus imaging device C15: In any one of fundus imaging devices B5 and C12 to C14, the local illumination region and the local imaging region are each formed in a slit shape.

  (30) Fundus photographing apparatus C16: In fundus photographing apparatus C15, a first slit-shaped member having a slit-shaped opening is provided on the optical path of the irradiation optical system, and the harmful light removing unit is provided with the slit-shaped opening. A second slit-shaped member that guides light passing through the opening to the light-receiving element, wherein the scanning unit includes the first slit-shaped member, the second slit-shaped member, and the first slit-shaped member. And a drive unit for moving the second slit-shaped member in a direction intersecting the optical axis.

  (31) Fundus imaging apparatus C17: In the fundus imaging apparatus C15, the scanning unit is a first scanning unit that is an optical scanner disposed on the irradiation optical system, and is separate from the first scanning unit. A second scanning section disposed on the light receiving optical system, wherein the light receiving element is a CMOS element, and line exposure by a rolling shutter function of the CMOS element is synchronized with scanning by the first scanning section. Thereby, the light receiving element also serves as the harmful light removing unit and the second scanning unit.

  (32) Fundus imaging device C18: In any one of the fundus imaging devices B5 and C12 to C14, the local illumination region and the local imaging region are each formed in a spot shape.

<Fundus photographing devices D1 to D5>
(33) Fundus photographing apparatus D1: an irradiation optical system that irradiates illumination light to the fundus of the subject's eye via an objective lens, and the objective lens is used in common with the illumination optical system. A photographing optical system including a light-receiving optical system having a light-receiving element for receiving light, and controlling one or both of the irradiation optical system and the light-receiving optical system to change photographing conditions so that at least two fundus images are formed. And an imaging processor that obtains a composite image by synthesizing at least two fundus images having different imaging conditions, based on a signal from the light receiving element.

  (34) Fundus photographing apparatus D2: In fundus photographing apparatus D1, the control means does not change the positional relationship between the optical axis of the photographing optical system and the visual axis of the eye to be examined, and the two images serving as the basis of the composite image Is obtained.

  (35) Fundus photographing apparatus D3: In fundus photographing apparatus D1 or D2, the photographing optical system includes a diopter correction optical system, and the control unit controls at least two of the fundus as a basis of the composite image. When capturing an image, the diopter correction amount in the diopter correction optical system is made different for each imaging by controlling the diopter correction optical system as the imaging condition.

  (36) Fundus photographing device D4: In the fundus photographing device D1 or D2, the control unit may use the fundus reflection light as the objective when photographing at least two fundus images that are the basis of the composite image. By controlling the photographing optical system, the state of separation from harmful light due to the illumination light reflected by the lens is made different for each photographing.

  (37) Fundus photographing apparatus D5: In any one of fundus photographing apparatuses D1 to D4, the illumination light is visible light, and the control unit acquires two fundus images serving as a basis of the composite image. Next, a continuous photographing process of photographing two fundus images at predetermined intervals in the order of the second fundus image and the first fundus image is performed.

<Fundus photographing devices E1 to E8>
(38) Fundus photographing apparatus E1: a photographing optical system including an irradiation optical system that irradiates illumination light to the fundus of the eye to be inspected, and a light receiving optical system that includes an imaging element that receives the illumination light returning from the fundus. A fundus imaging apparatus that obtains a fundus image that is a front image of the fundus based on a light reception signal from the imaging device, wherein the imaging optical system is configured to form a local imaging region in a slit shape. An optical element, and a scanning unit that scans the imaging region with respect to the fundus, wherein the optical element has a first width and a second width wider than the first width. The control means acquires a first fundus image as a captured image based on scanning of the imaging region of the first width, and controls the second width of the second fundus. A second fundus image as a photographed image based on the scanning of the photographing region; Give to.

  (39) Fundus imaging apparatus E2: In the fundus imaging apparatus E1, the control unit acquires a color image of the fundus as the first fundus image by changing the wavelength of the illumination light for each captured image. A fluorescence image of the fundus is acquired as the two fundus images.

  (40) Fundus photographing apparatus E3: In the fundus photographing apparatus E1, the control unit may select one of the first fundus image and the second fundus image based on information about a pupil size of the eye to be examined. Get selectively.

  (41) Fundus imaging apparatus E4: In any one of the fundus imaging apparatuses E1 to E3, the optical element is a rotating body in which a plurality of slit openings are arranged in a line on a circumference, and the scanning unit includes: The optical chopper that includes the rotating body, and drives the rotating body to rotate, whereby the plurality of slit openings are continuously traversed with respect to the optical path of the illumination light or the return light. A first area in which one or two or more first slit openings corresponding to the first width are continuously arranged, and one or two continuous second slit openings corresponding to the second width A second area disposed as above, wherein the control unit acquires 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. And the second Rear acquires the second fundus image based on a signal from the image sensor is exposed in the second period passes through the optical path.

  (42) Fundus imaging apparatus E5: In the fundus imaging apparatus E4, the control unit further controls the optical chopper to continuously rotate the rotating body, based on a signal from the image sensor. The fundus images are sequentially obtained at a fixed frame rate as observation images.

  (43) Fundus imaging apparatus E6: In the fundus imaging apparatus E5, the control unit may include, as the observation image, a first observation image based on a signal from the imaging element exposed in the first period, and the second period When a second observation image based on a signal from the imaging device exposed at the above is alternately acquired every time the first period and the second period are switched, when acquiring the observation image, In the second period, one of the light amount of the illumination light and the gain of the signal from the image sensor is reduced in comparison with the first period.

  (44) Fundus imaging apparatus E7: In the fundus imaging apparatus E6, the control unit exposes each frame of the observation image in at least a part of the first period and at least a part of the second period. It is obtained based on a signal from the imaging device.

  (45) Fundus photographing apparatus E8: In any one of fundus photographing apparatuses E1 to E7, the photographing optical system includes a diopter correction optical system for correcting a diopter error in the subject's eye, and the control unit includes: And selectively acquiring one of the first fundus image and the second fundus image according to the diopter correction amount in the diopter correction optical system.

Reference Signs List 1 fundus photographing apparatus 10 photographing optical system 10a irradiation optical system 10b light receiving optical system 17, 25 diopter correction optical system 22 objective lens 100 control unit E eye to be examined Er fundus

Claims (23)

An irradiation optical system that irradiates a slit-shaped illumination light to the fundus of the eye to be examined through an objective lens, the illumination optical system shares the objective lens, and further, a fundus image is formed based on the fundus reflection light of the illumination light. A light receiving optical system having an imaging surface to be subjected, and a photographing optical system including a scanning unit
A diopter correction optical system that corrects the diopter in the imaging optical system,
A fundus photographing apparatus that photographs a fundus image in a state where a diaphragm is arranged at a position different from a fundus conjugate position relating to both the objective lens and the diopter correction optical system. The diopter correction optical system, the irradiation-side correction amount that is the diopter correction amount in the irradiation optical system and the light-receiving side correction amount that is the diopter correction amount in the light-receiving optical system can be independently adjusted,
The fundus according to claim 1, wherein the control unit controls the diopter correction optical system when capturing the fundus image, and sets the irradiation-side correction amount and the light-receiving-side correction amount to different values. Shooting equipment. An illumination optical system that emits illumination light to the fundus of the subject's eye via the objective lens,
The objective lens is shared with the irradiation optical system, and further, a light receiving optical system having a light receiving element for receiving fundus reflection light of the illumination light,
A fundus imaging apparatus that acquires a fundus image based on a signal from the light receiving element,
A diopter correction optical system that independently adjusts the irradiation-side correction amount that is the diopter correction amount in the irradiation optical system and the light-receiving-side correction amount that is the diopter correction amount in the light-receiving optical system,
A fundus photographing apparatus comprising: a control unit that controls the diopter correction optical system and sets the irradiation-side correction amount and the light-receiving-side correction amount to different values.   The control unit adjusts the light-receiving-side correction amount according to the refractive power of the eye to be inspected, and a condensing position of the illumination light via the diopter correction optical system is formed via the objective lens. The fundus imaging apparatus according to claim 2, wherein the irradiation-side correction amount is set such that the irradiation-side correction amount is arranged at a position further away from the objective lens with respect to an intermediate image plane of the fundus.   The control unit adjusts the light-receiving-side correction amount according to the refractive power of the eye to be inspected, and sets the irradiation-side correction amount to a value having a smaller absolute value than the light-receiving-side correction amount. The fundus imaging apparatus according to any one of claims 1 to 4.   The control unit adjusts a difference value between the irradiation-side correction amount and the light-receiving-side correction amount to a value larger than that in the first shooting mode in the first shooting mode and the second shooting mode. The fundus photographing apparatus according to any one of claims 2 to 5, wherein the photographing mode is switched between a second photographing mode for photographing an image and the photographing mode according to the refractive power of the eye to be inspected.   The fundus imaging apparatus according to claim 6, wherein the control unit adjusts the difference value in consideration of a size of a pupil of the eye to be inspected.   In the first shooting mode, the control unit shoots the fundus image by matching the irradiation-side correction amount and the light-receiving side correction amount, and in the second shooting mode, the irradiation-side correction amount and the light receiving amount. The fundus photographing apparatus according to claim 6, wherein the fundus image is photographed by making the side correction amounts different from each other. The refractive power of the subject's eye is roughly divided into a first range and a second range on the minus diopter side with respect to the first range,
The control unit switches to the first photographing mode when the refractive power of the subject's eye is in the first range, and switches to the second photographing mode when the refractive power of the subject's eye is in the second range. The fundus imaging apparatus according to any one of claims 6 to 8, which performs switching. Having a refractive power information obtaining unit for obtaining refractive power information about the refractive power of the eye to be examined,
The fundus imaging apparatus according to claim 6, wherein the control unit sets the irradiation-side correction amount and the light-receiving-side correction amount based on the refractive power information.   The fundus imaging apparatus according to claim 10, wherein the refractive power information acquiring unit detects a focus state in the light receiving optical system, and acquires the refractive power information based on a detection result of the focus state. An optical path coupling unit disposed between the objective lens and the light receiving element and coupling an optical path of the irradiation optical system and an optical path of the light receiving optical system,
The diopter correction optical system,
A first diopter correction optical system disposed on one optical path of the irradiation optical system and the light receiving optical system,
On the other optical path to the one, or, a second diopter correction optical system disposed on a common optical path of the irradiation optical system and the light receiving optical system,
The control unit controls the first diopter correction optical system and the second diopter correction optical system individually, so that the irradiation-side correction amount and the light-receiving-side correction amount are different from each other. The fundus imaging apparatus according to any one of claims 2 to 12, which is set. A first driving unit that drives at least one optical element included in the first diopter correction optical system;
A second driving unit that drives at least one optical element included in the second diopter correction optical system,
The fundus imaging apparatus according to claim 12, wherein the control unit controls the first driving unit and the second driving unit independently. The illumination optical system forms a local illumination region in a part of a photographing range in the fundus,
The diopter correction optical system is interposed between the objective lens and the diopter correction optical system, and is disposed on the optical path of the light receiving optical system. A harmful light removing unit for receiving light to the element and removing light from other than the imaging region,
The fundus imaging apparatus according to any one of claims 1 to 13, further comprising: a scanning unit that scans the local illumination area and the local imaging area on the fundus in synchronization with each other.   The harmful light removing unit is arranged at a position conjugate with the fundus with respect to at least the objective lens and the diopter correction optical system in a state where the light-receiving-side correction amount according to the refractive power of the eye to be inspected is set. Item 15. The fundus photographing apparatus according to item 14.   The diopter correction optical system, in each of the irradiation optical system and the light receiving optical system, maintains an image height on the image side regardless of the combination of the irradiation side correction amount and the light receiving side correction amount, telecentric optics The fundus imaging apparatus according to any one of claims 2, 14 and 15, comprising a system.   The fundus imaging apparatus according to claim 2, wherein the local illumination region and the local imaging region are each formed in a slit shape. A first slit-shaped member having a slit-shaped opening on the optical path of the irradiation optical system;
The harmful light removing unit is a second slit-shaped member that has the slit-shaped opening and guides light passing through the opening to the light-receiving element,
The scanning unit includes the first slit-shaped member and the second slit-shaped member, and a driving unit that moves the first slit-shaped member and the second slit-shaped member in a direction intersecting an optical axis. Item 18. The fundus imaging apparatus according to Item 17.   A first scanning unit that is an optical scanner disposed on the irradiation optical system; and a second scanning unit that is separate from the first scanning unit and disposed on the light receiving optical system. Wherein the light receiving element is a CMOS element, and the line exposure by the rolling shutter function of the CMOS element is synchronized with the scanning by the first scanning unit, so that the light receiving element includes the harmful light removing unit and the 18. The fundus imaging apparatus according to claim 17, wherein the apparatus also serves as a second scanning unit.   20. The fundus imaging apparatus according to claim 2, wherein the local illumination region and the local imaging region are each formed in a spot shape.   The fundus imaging apparatus according to claim 1, wherein the stop is previously arranged at a position different from any one of the imaging plane and a conjugate position of the imaging plane.   22. The fundus imaging apparatus according to claim 21, wherein the aperture is disposed in advance at a position away from the conjugate position of the imaging surface on the plus diopter side. The said control means, when imaging the fundus image, controls the diopter correction optical system, and adjusts the imaging surface so as to be arranged at a fundus conjugate position of the eye to be examined. 23. The fundus imaging apparatus according to any one of 22.

Images