JP5435698B2 - Fundus camera - Google Patents

Description

  The present invention relates to a fundus camera that photographs the fundus of a subject's eye.

  In a fundus camera that photographs the fundus of a subject's eye, a focusing lens that is movable in the optical axis direction is arranged in the photographing optical path of the photographing optical system so that focusing with the fundus is possible. In addition, a split index is projected onto the fundus of the subject's eye via a spot mirror formed on a focus bar that is inserted into and removed from the optical path of the illumination optical system for illuminating the fundus of the subject's eye, and its reflected light Is provided by an image sensor for the fundus oculi observation optical system, and the examiner focuses from the split index (focus index) separation state when the image captured by the fundus oculi image sensor is displayed on the monitor. Grasp the deviation.

JP 2007-202724 A

  First, as a first problem, when a focus index as described above is projected, a black dot plate is provided in the optical system for projecting the focus index in order to remove reflection of the objective lens based on the index projection light beam. Such a black spot plate limits the degree of freedom in optical design. For example, in the case of a conventional configuration in which an optical system for projecting a focus index is provided with a black spot plate for preventing lens reflection, the moving range of the focus bar is limited due to the presence of the black spot plate. For this reason, under the situation where the diopter correction lens is inserted, the focus index cannot be suitably projected, the focus bar is retracted from the optical path, and the focus adjustment is performed visually without the focus index. .

  As a second problem, in recent years, the fundus fundus of a subject is often imaged by a two-dimensional image sensor with a high pixel, and the acquired fundus image is often displayed on a large screen such as a personal computer display for observation. In such a case, for example, when photographing an astigmatic eye with high intensity, the fundus image is noticeably blurred and difficult to observe even though the image is photographed in focus. There is.

  However, it is difficult for the photographer to determine what causes such blurring of the image, and it is difficult to take a countermeasure.

  In view of the first problem, the present invention provides a fundus camera that can suitably perform focus adjustment on the fundus of a subject without the need to provide a black dot plate in an optical system for projecting a focus index. This is a technical issue. In addition, in view of the second problem, an object of the present invention is to provide a fundus camera that can easily know the state of the subject's eye at the time of photographing.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1)
An illumination optical system having an illumination light source and illuminating the eye fundus of the subject via the objective lens with illumination light emitted from the illumination light source;
Fundus photography that has a focusing lens arranged so as to be movable in the direction of the optical axis, and receives the fundus reflected light from the illumination optical system through the objective lens and the focusing lens to photograph the fundus of the subject's eye A fundus photographing optical system in which a diopter correction lens for correcting the diopter of an eye having a refractive error of intensity is detachably arranged with respect to the optical path;
Focus detection optics having an index projection optical system having a projection light source and projecting a focus index onto the fundus of the subject's eye and a light receiving optical system having a light receiving element for receiving fundus reflected light by the index projection optical system The system,
A fundus camera comprising:
A movement mechanism having a drive unit and capable of moving a part of a focus detection optical system including at least one of the projection light source and the light receiving element in an optical axis direction, in which the diopter correction lens is inserted A moving mechanism having a movable range including a diopter correction range due to movement of the focusing lens at
Control means for controlling the driving of the drive unit in conjunction with the movement of the focusing lens, and when the diopter correction lens is inserted, depends on the inserted diopter correction lens and the moving position of the focusing lens. And a control unit that moves a part of the focus detection optical system using the moving mechanism at a moving position corresponding to the diopter correction amount.

  According to the present invention, it is not necessary to provide a black spot plate in an optical system for projecting a focus index, and focus adjustment with respect to the subject's eye fundus can be suitably performed. Further, according to the present invention, the state of the subject's eye can be easily known at the time of imaging.

  Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an optical system and a control system of a fundus camera according to the present embodiment. The optical system includes an illumination optical system 10, a fundus observation / imaging optical system 30 that captures a fundus image of a subject's eye, a focus index projection optical system 40, an alignment index projection optical system 50, an anterior segment observation optical system 60, a fixed eye. The optotype presenting optical system 70 is roughly divided.

  <Illumination Optical System> The illumination optical system 10 includes an observation illumination optical system and a photographing illumination optical system. The photographing illumination optical system includes a photographing light source 14 such as a flash lamp, a condenser lens 15, a first light shielding plate 17a (for example, a ring slit) having a circular light shielding part, a ring having a circular light shielding part and a ring-shaped opening. A slit 17b, a second light shielding plate 17c having a circular light shielding portion (for example, a ring slit), a relay lens 18, a mirror 19, a black spot plate 20 having a black spot at the center, a relay lens 21, a perforated mirror 22, and an objective lens 25 are provided. Have.

  The observation illumination optical system includes a light source 11 such as a halogen lamp, an infrared filter 12 that transmits near-infrared light having a wavelength of 750 nm or more, a condenser lens 13, and a dichroic disposed between the condenser lens 13 and the ring slit 17b. The optical system from the mirror 16 and the first light shielding plate 17a to the objective lens 25 is provided. The dichroic mirror 16 has a characteristic of reflecting light from the infrared light source 11 and transmitting light from the imaging light source 14.

  In the optical system, when the positional relationship between the subject's eye and the apparatus main body 3 in the working distance direction is placed at a predetermined alignment reference position (reference center), the pupil (iris) of the subject's eye and the ring slit 17b. Are arranged in a conjugate position. In addition, the optical design is such that the first light-shielding plate 17a is conjugated with the cornea of the subject's eye and the second light-shielding plate 17c is conjugated with the rear surface of the lens of the subject's eye with the ring slit 17b being conjugated with the pupil. Has been. The first light shielding plate 17a, the ring slit 17b, and the second light shielding plate 17c arranged in the illumination optical system 10 are provided with the light shielding member 17 arranged so as to be conjugated with a predetermined part of the anterior eye portion of the subject. As a harmful reflected light removing means for preventing the corneal reflection and the crystalline lens reflection caused by the fundus illumination light for photographing the fundus from being included in the photographing light flux from the fundus and being received by the photographing imaging device 35 (described later). Function.

  <Fundus observation / fundus imaging optical system> The fundus observation / imaging optical system 30 includes an objective lens 25, a photographing diaphragm 31 located near the aperture of the perforated mirror 22, a focusing lens 32 movable in the optical axis direction, and an imaging lens. 33. At the time of fundus photography, a flip-up mirror 34 that can be inserted and removed from the optical path by the insertion / removal mechanism 39 is provided, and the photographing optical system and the fundus observation optical system share the objective lens 25 and the optical system from the photographing aperture 31 to the imaging lens 33. To do. The photographing aperture 31 is disposed at a position substantially conjugate with the pupil of the subject eye E with respect to the objective lens 25. The focusing lens 32 is moved in the optical axis direction by a moving mechanism 49 including a motor. Reference numeral 35 denotes a photographing two-dimensional image sensor having sensitivity in the visible range. A polarizing beam splitter 37 that reflects P-polarized light and transmits S-polarized light, a relay lens 36, and an observation two-dimensional imaging device 38 that has sensitivity in the infrared region are disposed in the optical path in the reflection direction of the flip-up mirror 34. . Diopter correction lenses 32a and 32b (a minus lens 32a and a plus lens 32b) that can be inserted into and removed from the photographing optical path of the photographing optical system 30 by driving the drive unit 32c between the lens 32 and the photographing diaphragm 31. Is provided. The lenses 32a and 32b are inserted into the optical path manually or automatically when the subject's eye is a strong refractive error eye. When the lenses 32 a and 32 b are inserted into the optical path, a corresponding diopter correction amount is given to the photographing optical system 30.

  A dichroic mirror (wavelength selective mirror) 24 that can be inserted and removed as an optical path branching member is provided obliquely between the objective lens 25 and the perforated mirror 22. The dichroic mirror 24 reflects the wavelength light (center wavelength 940 nm) of the alignment index projection optical system 50 and the anterior ocular segment illumination light source 58, and includes a light source wavelength (center wavelength 880 nm) of the wavelength light of the fundus observation illumination. It has a characteristic of transmitting through. At the time of shooting, the dichroic mirror 24 is flipped up by the insertion / removal mechanism 66 and retracts out of the optical path. The insertion / removal mechanism 66 can be composed of a solenoid and a cam.

  The light beam emitted from the observation light source 11 is converted into an infrared light beam by the infrared filter 12 and reflected by the condenser lens 13 and the dichroic mirror 16 to illuminate the first light shielding plate 17a. The light transmitted through the first light shielding plate 17a reaches the perforated mirror 22 through the ring slit 17b, the second light shielding plate 17c, the relay lens 18, the mirror 19, the black spot plate 20, and the relay lens 21. The light reflected by the perforated mirror 22 is transmitted through the dichroic mirror 24, and once converged in the vicinity of the pupil of the eye E by the objective lens 25, then diffuses and illuminates the eye fundus of the subject.

  Reflected light from the fundus is obtained by the objective lens 25, the dichroic mirror 24, the aperture of the perforated mirror 22, the photographing aperture 31, the focusing lens 32, the imaging lens 33, the flip-up mirror 34, the polarization beam splitter 37, and the relay lens. An image is formed on the image sensor 38 via 36. The output of the image sensor 38 is input to the control unit 80, and the fundus observation image of the subject's eye captured by the image sensor 38 is displayed on the monitor 8.

  The luminous flux emitted from the imaging light source 14 passes through the dichroic mirror 16 via the condenser lens 15 and then passes through the same optical path as the illumination light for fundus observation, and the fundus is illuminated with visible light. Then, the reflected light from the fundus is imaged on the two-dimensional image sensor 35 through the objective lens 25, the aperture of the perforated mirror 22, the photographing aperture 31, the focusing lens 32, and the imaging lens 33.

  <Focus Index Projection Optical System> A focus index projection optical system (hereinafter abbreviated as a projection optical system) 40 includes an infrared light source 41, a slit index plate 42, and two declination prisms 43 attached to the index plate 42, A polarization beam splitter 44 is provided. Further, the projection optical system 40 shares the optical path from the beam splitter 44 to the lens 25 with the illumination optical system 10. The polarization beam splitter 44 is disposed in the optical path of the illumination optical system 10 and is used as an optical coupling member that couples the optical path of the illumination optical system 10 and the optical path of the projection optical system 40.

  In the projection optical system 40, two declination prisms 43 formed so that the declination directions of the light have a pair of upper and lower relationships are arranged side by side with the projection optical axis L3 interposed therebetween, and formed on the indicator plate 42. It is overlapped with a slit extending to the left and right.

  The projection optical system 40 has a first polarizing member for setting the index light beam to a predetermined polarization direction, and the observation optical system 30 images the index light beam having a predetermined polarization direction obtained by the first polarizing member. A polarizing member that restricts the element 38 is provided.

  More specifically, each of the index projection optical system 40 and the observation optical system 30 is examined by transmitting or reflecting either a linearly polarizing plate having a polarization direction orthogonal to each other or light having a polarization direction orthogonal to each other. A polarizing beam splitter is disposed so as to face the human eye and reflect or transmit the other to be received by the image sensor 38. As a result, the reflected light from the objective lens 25 by the index projection light beam is restricted from traveling toward the image sensor 38.

  For example, the polarization beam splitter 44 is disposed between the illumination light source (the light source 11 and the light source 14) of the illumination optical system 10 and the perforated mirror 22 (including a detachable configuration). For example, a polarization beam splitter that transmits P-polarized light and reflects S-polarized light is used. Further, the projection optical axis L3 of the projection optical system 40 is shifted in a direction perpendicular to the optical axis L2 of the illumination optical system 10 in order to avoid that the focus index on the fundus overlaps the shadow of the black spot plate 20. You may make it arrange | position to a position.

  The projected light beam emitted from the light source 41 passes through the slit of the indicator plate 42, is deflected in each direction by the prism 43, and then reflected by the beam splitter 44. Here, the S-polarized light of the light beam (natural light) from the light source 41 is reflected by the beam splitter 44.

  The light beam (S-polarized light) reflected by the beam splitter 44 is projected onto the fundus through the relay lens 21, the perforated mirror 22, the dichroic mirror 24, and the lens 25. The focusing light beam projected on the fundus is irregularly reflected by the fundus and becomes P-polarized light and S-polarized light. The fundus reflection light flux is incident on the polarization beam splitter 37 via the lens 25 and the opening of the perforated mirror 22 to the flip-up mirror. Here, the fundus reflected light by the focus index is reflected by the polarization beam splitter 37 and is transmitted through the S-polarized light. The fundus reflection light (P-polarized light) reflected by the polarization beam splitter 37 forms an image on the image sensor 38 via the relay lens 36.

  In this case, the projection optical system 40 is used as an index projection optical system that has a projection light source and projects a focus index onto the fundus of the subject's eye. The observation optical system 30 having the observation two-dimensional imaging element 38 is used as a light receiving optical system having a light receiving element that receives fundus reflected light from the projection optical system 40. The projection optical system 40 and the observation optical system 30 form a focus detection optical system.

  FIG. 2 shows an image output from the image sensor 38 on the monitor 8. As shown in the figure, when split indices (focus indices) S1 and S2 are projected onto the fundus, they are separated in a predetermined direction on the fundus according to the focus state of the apparatus with respect to the fundus of the subject's eye. The focus index images S1 and S2 are captured together with the fundus image by the image sensor 38.

  When the imaging signal is output from the imaging element 38 to the monitor 8, the examiner can grasp the focus shift from the split index separation state. Further, the control unit 80 electrically detects the fundus focus state based on the split index separation state, and automatically moves the lens 32 based on the detection result (auto focus control).

  The reflected light generated when the projection light beam for focusing passes through each lens surface, cornea, and crystalline lens of the objective lens 25 is almost specularly reflected and reaches the polarizing beam splitter 37 and is transmitted as it is with S-polarized light. The For this reason, it is possible to avoid flare and ghost due to the projection of the focus index from being mixed into the image sensor 38.

  A part of the projection optical system 40 including the light source 41 (the light source 41, the slit indicator plate 42, and the deflection prism 43) is moved in the optical axis direction in conjunction with the lens 32. For example, when the lens 32 is placed at a position corresponding to the normal eye, a part of the projection optical system 40 (light source 41, slit index plate 42, so that the fundus of the normal eye and the opening of the projection plate 42 are substantially conjugate with each other). The prism 43) is moved. When the lens 32 is placed at a position where the subject's eye having a predetermined spherical power (for example, −3D) is in focus, the fundus of the subject's eye and the opening of the projection plate 42 are substantially conjugate. A part of the projection optical system 40 is moved so that

  The moving mechanism 46 has a motor and moves a part of the projection optical system 40 including the light source 41 in the optical axis direction with respect to the beam splitter 44. As for the movement range of the projection optical system 40, in addition to the movement range corresponding to the diopter correction amount due to only the movement of the lens 32, the movement range corresponding to the diopter correction amount due to the insertion of the lenses 32a and 32b is secured. That is, the moving mechanism 46 has a movable range including a diopter correction range due to the movement of the focusing lens 32 in a state where the diopter correction lens is inserted.

  In this case, the movement range of the projection optical system 40 is switched according to the insertion / removal state of the lenses 32a and 32b with respect to the photographing optical path. When the movement range is set according to the insertion / removal state, the projection optical system 40 is moved in conjunction with the lens 32 within the movement range (details will be described later).

  Returning to the description of FIG. <Alignment Index Projection Optical System> The alignment index projection optical system 50 that projects the alignment index beam is 45 degrees concentrically about the photographing optical axis L1 as shown in the diagram in the dotted line A in the upper left of FIG. A plurality of infrared light sources are arranged at intervals, and a first index projection optical system (0) having an infrared light source 51 and a collimating lens 52 arranged symmetrically with respect to a vertical plane passing through the photographing optical axis L1. And a second index projection optical system having six infrared light sources 53 arranged at positions different from the first index projection optical system. In this case, the first index projection optical system projects an infinite distance index on the cornea of the subject's eye E from the left and right directions, and the second index projection optical system moves the finite distance index on the cornea of the subject's eye E up and down. Projection is performed from a direction or an oblique direction. In FIG. 1, for convenience, the first index projection optical system (0 degrees and 180 degrees) and only a part of the second index projection optical system (45 degrees and 135 degrees) are shown. .

  <Anterior Eye Observation Optical System> An anterior eye observation (imaging) optical system 60 that images the anterior eye part of a subject's eye is provided with a field lens 61, a mirror 62, a diaphragm 63, and a relay on the reflection side of the dichroic mirror 24. A lens 64 and a two-dimensional imaging element (light receiving element) 65 having infrared sensitivity are provided. The two-dimensional imaging element 65 also serves as an imaging means for detecting an alignment index, and the anterior segment illuminated by the anterior segment illumination light source 58 that emits infrared light having a center wavelength of 940 nm and the alignment index are imaged. The anterior segment illuminated by the anterior segment illumination light source 58 is received by the two-dimensional imaging element 65 from the objective lens 25, the dichroic mirror 24, and the field lens 61 via the relay lens 64 optical system. In addition, the alignment light beam emitted from the light source of the alignment index projection optical system 50 is projected onto the subject's eye cornea, and the cornea reflection image is received by the two-dimensional image sensor 65 via the objective lens 25 to the relay lens 64 ( Projected). The output of the two-dimensional image sensor 65 is input to the control unit 80, and the anterior segment image captured by the two-dimensional image sensor 65 is displayed on the monitor 8. The anterior ocular segment observation optical system 60 also serves to detect the alignment state of the apparatus main body with respect to the subject's eye.

  <Fixed Target Presenting Optical System> A fixed target presenting optical system 70 for presenting a fixed target for fixing a subject's eye includes a red light source 74, a light shielding plate 71 in which an aperture is formed, and a relay lens. 75, and shares the optical path of the observation optical system 30 from the flip-up mirror 34 to the objective lens 25 via the polarization beam splitter 37.

  In this case, the light shielding plate 71 is illuminated from behind by the light source 74 to become a fixation target (fixation lamp). Then, the light beam from the fixation target passes through the relay lens 75, the polarization beam splitter 37, the flip-up mirror 34, the imaging lens 33, the focusing lens 32, the perforated mirror 22, the dichroic mirror 24, and the objective lens 25. The light is condensed on the eye fundus of the examiner, and the subject visually recognizes the light flux from the opening hole 71 as a fixation target.

  <Control System> The two-dimensional imaging elements 65, 38, and 35 are connected to the control unit 80. The control unit 80 detects an alignment index from the anterior segment image captured by the two-dimensional image sensor 65. In addition, the control unit 80 detects a focus index from the fundus image captured by the two-dimensional image sensor 38. The control unit 80 is connected to the monitor 8 and controls the display image. In addition, the control unit 80 is connected to a moving mechanism 49, a moving mechanism 46, an insertion / removal mechanism 39, a switch unit 84 having various switches, a memory 85 as a storage unit, and light sources. The switch unit 84 is provided with a focus adjustment switch 84a for performing focus adjustment, a shooting start switch 84b, a changeover switch 84c for inserting and removing the lenses 32a and 32b, and the like.

  The operation of the apparatus having the above configuration will be described. First, the examiner supports the subject's face with a face support unit (not shown). Here, the examiner moves the apparatus main body in which the above-described optical system is built up to the left and right and up and down by operating a joystick (not shown) to perform alignment with the eye of the subject. In this case, alignment can be performed smoothly by outputting the anterior segment image captured by the anterior segment observation optical system 60 to the monitor 8.

  When rough alignment is completed, a fundus image by the image sensor 38 is displayed on the monitor 8. The examiner finely adjusts the alignment state by manual operation of a joystick (not shown) so that the fundus image can be taken in a desired state while viewing the fundus image.

  After finely adjusting the alignment by observing the fundus image, focus index images S1 and S2 by the focus target projection optical system 40 are projected at the center as shown in FIG. Based on this, the lens 32 is moved in the optical axis direction to focus the fundus.

  In the initial state, since the diopter correction lens is not inserted in the photographing optical path, the control unit 80 is linked to the movement of the lens 32 within the movement range corresponding to the diopter correction range based on the movement of the lens 32 only. Thus, the index projection optical system 40 is moved in the optical axis direction (see FIG. 3A).

  Note that focusing is performed by manual focus of the examiner using the focus adjustment switch 84a or auto focus by the control unit 80. In the case of autofocus, the control unit 80 controls driving of the moving mechanism 49 so that the focus index images S1 and S2 coincide. Note that after the focusing is completed, photographing is performed based on a trigger signal output automatically or manually.

  Here, when a trigger signal for starting imaging is generated, the control unit 80 drives the insertion / removal mechanism 39 to disengage the flip-up mirror 34 from the optical path, and drives the insertion / removal mechanism 66 to move the dichroic mirror 24. While being separated from the optical path, the photographing light source 14 emits light. At this time, a fundus image is captured by the two-dimensional image sensor 35 and the captured image data is stored in the memory 85. Then, the control unit 80 switches the display screen of the monitor 8 to a color fundus image captured by the two-dimensional image sensor 35.

  In the above configuration, when the subject's eye is an intense myopic eye or an intense hyperopic eye and the focus cannot be adjusted, the examiner pushes the changeover switch 84c and inserts the lenses 32a and 32b into the imaging optical path to adjust the focus. In this case, the lenses 32a and 32b may be automatically inserted. For example, if the focus does not match even when the lens 32 reaches the movement limit position, a diopter correction lens is automatically inserted.

  Here, the control unit 80 uses the moving mechanism 49 to move a part of the projection optical system 40 to a movement position corresponding to the diopter correction amount based on the inserted diopter correction lens and the movement position of the lens 32. .

  More specifically, the movement position of a part of the index projection optical system 40 including the projection light source 41 is corrected according to the insertion / removal state of the diopter correction lens. Note that the control unit 80 uses a sensor (for example, a photosensor) that can be installed in the vicinity of the lens 32a and the lens 32b, a switching signal output from the selector switch 84c, a driving signal from the driving unit, and the like, and a diopter for the photographing optical path Individual insertion states of the correction lens can be determined.

  FIG. 3 is a specific example showing the movement range of the index projection optical system 40 set according to when the lenses 32a and 32b are retracted, when the lens 32a is inserted, and when the lens 32b is inserted. When the lenses 32a and 32b are retracted, as shown in FIG. 3A, a predetermined diopter correction range (−12D to 0D to + 12D) due to the movement of the lens 32 when the lenses 32a and 32b are retracted. The movement range corresponding to is set.

  As shown in FIG. 3B, when the lens 32a is inserted, a predetermined diopter correction is performed by moving the lens 32 in a state where the lens 32a (for example, a lens having a diopter correction amount of −18D) is inserted. A moving range corresponding to the range (for example, −30D to −18D to −6D) is set.

  More specifically, when the lens 32a is inserted, the control unit 80 moves the movement direction (− direction) and the movement distance of the projection optical system 40 corresponding to the diopter correction amount (for example, −18D) of the lens 32a. Set. For example, the control unit 80 adds the diopter correction amount (−18D) of the diopter correction lens 32a to the move position (−12D) of the projection optical system 40 before the lens is inserted (−30D). Then, the projection optical system 40 is moved.

  In this case, the control unit 80 may control the driving of the moving mechanism 49 to move the lens 32 to a moving position corresponding to the diopter correction amount before insertion of the lens 32a. Thereby, after shifting to the lens insertion state, focus adjustment from the diopter correction amount before insertion of the lens 32a becomes possible.

  As shown in FIG. 3C, when the lens 32b is inserted, a predetermined diopter correction range due to the movement of the lens 32 with the lens 32b (for example, a lens with a diopter correction amount of + 18D) inserted. A moving range corresponding to (for example, + 6D to + 18D to + 30D) is set. In addition, about a specific operation | movement, since the method similar to the lens 32a can be used, detailed description is abbreviate | omitted.

  When the movement of the projection optical system 40 is completed as described above, it is possible to perform focusing with respect to an eye with abnormal refractive power. Therefore, based on the separation information of the focus index images S1 and S2, the control unit 80 performs driving control of the moving mechanism 49 so that the two coincide with each other, thereby focusing the fundus. Further, manual focusing by the examiner is also possible so that the index images S1 and S2 are matched.

  In this case, the control unit 80 illuminates the index projection optical system 40 so as to be interlocked with the movement of the lens 32 within the movement range corresponding to the diopter correction range by the inserted diopter correction lens and the movement of the lens 32. Move in the axial direction. For example, when the lens 32a is inserted, the control unit 80 moves the projection optical system 40 within a movement range corresponding to the lens 32a. When the lens 32 is moved, the control unit 80 moves the projection optical system 40 by the amount of diopter correction due to the movement of the lens 32.

  With the configuration as described above, even if the subject's eye is an intense refractive error eye and the diopter correcting lens is inserted in the photographing optical path of the photographing optical system 30, the focus on the fundus The index is received on the image sensor 38 in a state where focus detection is possible. For this reason, appropriate autofocus control is possible. Further, the examiner can perform manual focus by the same operation as in the state where the diopter correction lens is not inserted.

  In the above-described configuration, a correction lens corresponding to the insertion of the diopter correction lens may be inserted into and removed from the optical path of the projection optical system 40. For example, when the lens 32 a is inserted, a minus lens corresponding to the diopter correction amount of the lens 32 a is inserted between the beam splitter 44 and the prism 43. In this way, the movement amount of the projection optical system 40 can be reduced. In this case, the movable range of the projection optical system 40 with the lens 32a inserted may be substantially the same as the movable range of the projection optical system 40 with the lens 32a removed. is there.

  Next, a configuration according to the second embodiment will be described. In FIG. 4, the same reference numerals as those in FIG. 1 have the same configuration / function unless otherwise specified. In FIG. 4, as a configuration for detecting the focus state with the subject's eye fundus, an index projection optical system 140 that projects a spot-like light beam onto the subject's eye fundus through the center of the pupil of the subject's eye; The light receiving optical system 160 takes out the reflected light from the eye fundus of the subject as a predetermined pattern image (for example, a ring pattern image or a plurality of spot images) from the anterior eye portion of the subject and causes the two-dimensional light receiving element to receive the light. And are provided.

  In FIG. 4A, the projection optical system 140 is an infrared point light source 141 such as an LED or SLD arranged on the projection optical axis L3, a projection lens 142, and an optical path dividing member that branches the focus light beam and the fundus observation light beam. In addition, the optical path from the beam splitter 144 to the lens 32 to the objective lens 25 is shared with the fundus oculi observation optical system 30. The dichroic mirror 137 has a characteristic of reflecting visible light and transmitting infrared light.

  On the other hand, the light receiving optical system 160 shares the optical path from the objective lens 25 to the beam splitter 169 with the illumination optical system 10, and further, a pinhole opening 161 disposed at a substantially fundus conjugate position in the reflection direction of the beam splitter 169, It includes a collimator lens 163, a ring lens 165, and a two-dimensional light receiving element 167 disposed substantially at the fundus conjugate position. A part of the light receiving optical system 160 including the light receiving element 167 (for example, the pinhole opening 161 to the two-dimensional light receiving element 167) moves in the optical axis direction in conjunction with the movement of the lens 32 by driving the moving mechanism 46. It has a possible configuration. For example, when the lens 32 is placed at a position corresponding to the normal eye, a part of the light receiving optical system 160 is moved so that the fundus of the normal eye and the opening 161 are substantially conjugate. Further, when the lens 32 is placed at a position where the subject's eye having a predetermined spherical power (for example, −3D) is in focus, the fundus of the subject's eye and the opening 161 are substantially conjugate. The projection optical system 40 is partially moved. A part of the light receiving optical system 160 moved in conjunction with the movement of the lens 32 corresponds to the insertion of the lenses 32a and 32b, like the part of the projection optical system 40 in the first embodiment shown in FIG. The movement position is corrected. A configuration in which a part of the projection optical system 140 including the light source 140 is moved along with the movement of the light receiving optical system 160 may be adopted.

  Here, the ring lens 165 includes a lens portion and a ring indicator plate having a ring opening, and is disposed at a position substantially conjugate with the pupil. The two-dimensional light receiving element 167 is disposed at the focal position of the lens unit, and is conjugate with the fundus when the fundus is in focus with the image sensor 38 (image sensor 35). Here, the ring indicator plate is positioned substantially conjugate with the anterior eye portion of the subject between the lens 32 and the two-dimensional light receiving element 167 (for example, a location substantially conjugate with the subject's eye pupil or the subject's eye). (Position substantially conjugate with the cornea).

  The light emitted from the light source 141 passes through the lens 142, the flip-up mirror 34, and the objective lens 25, and is projected onto the eye fundus of the subject's eye, and a spot-like point light source image is projected onto the fundus. The point light source image projected onto the fundus is reflected and scattered and exits the subject's eye, passes through the reflecting surface of the objective lens 25 to the hole mirror, and passes through the beam splitter 169, the pinhole aperture 161, and the collimator lens 163. Then, after being converged by the ring lens 165, it is formed as a ring image on the two-dimensional light receiving element 167.

  Here, the light reception signal from the two-dimensional light receiving element 167 is input to the control unit 80. Here, when the fundus of the subject's fundus is in focus, a thin ring image with the same size as the ring lens 165 and with little blur is formed on the two-dimensional light receiving element 167. On the other hand, when the fundus of the subject's fundus is out of focus, a ring image that is a blurred thick ring image that is different from the size of the focused ring image is received on the two-dimensional light receiving element 167. Is done. In this case, when there is a spherical refraction error of the subject's eye, the ring image has a size proportional to the magnitude of the spherical refraction error of the subject's eye. If there is an astigmatism refraction error, the ring image formed on the two-dimensional light receiving element 167 has an elliptical shape according to the astigmatism refraction error.

  Therefore, the control unit 80 can detect the focus state of the subject's eye by analyzing the ring image formed on the two-dimensional light receiving element 167. Then, the control unit 80 performs driving control of the moving mechanism 46 and the moving mechanism 49 based on the detected focus state, thereby performing focus adjustment on the fundus. In this case, the control unit 80 moves the lens 32 in the optical axis direction using the moving mechanism 49 and moves a part of the light receiving optical system 160 using the moving mechanism 46. For example, the ring image on the two-dimensional light receiving element 167 is made the thinnest or brightest so that the two-dimensional light receiving element 167 is aligned with the fundus of the subject's eye. As a result, focus adjustment between the fundus imaging image sensor 35 (or the fundus observation image sensor 38) and the eye fundus of the subject is performed.

  Further, in the second embodiment, instead of the beam splitter 144 and the beam splitter 169, one of the lights whose polarization directions are orthogonal to each other as shown in the first embodiment is reflected and the other light is reflected. A polarizing beam splitter having a characteristic of transmitting the light may be used.

  Further, in the above configuration, when astigmatism detection or ring image acquisition is not performed, as shown in FIG. 4B, two apertures are formed at positions that are equidistant from the light receiving optical axis as a pattern index plate. You may make it use the aperture stop 170 and the imaging lens 171 which condenses the light which passed the 2 aperture stop 170 as a condensing member on the two-dimensional light receiving element 167. FIG. In the case of FIG. 4B, when the focus is achieved, the two spot images overlap to form one spot image on the light receiving optical axis on the two-dimensional light receiving element 167, and the focus is shifted. Two spot images are formed on the two-dimensional light receiving element 167.

  As the focus detection optical system, by providing a configuration (see FIG. 4A) in which the ring index image is received by the two-dimensional light receiving element, it is possible to determine what causes the image blur. When the subject's eye is an astigmatic eye, the ring image on the two-dimensional light receiving element 167 has an elliptical shape having a major axis and a minor axis. The major axis and minor axis of the ring image change according to the astigmatism power of the subject's eye.

  Here, the control unit 80 detects the focus state based on the ring image acquired by the two-dimensional light receiving element 167. Then, the control unit 80 drives and controls the moving mechanism 49 so that the lens 32 is disposed at a position corresponding to the equivalent spherical power of the subject's eye based on the detected focus state. Further, the control unit 80 moves a part of the light receiving optical system 160 in conjunction with the movement of the lens 32 (hereinafter the same). In the present embodiment, a position corresponding to the equivalent spherical power of the subject's eye is set as the focus end position.

  In this case, the control unit 80 detects the image position of each ring image in the meridian direction, and calculates the spherical power (S), the astigmatism power (C), and the astigmatic axis angle (A) based on the detected image position information. To do. Then, the control unit 80 calculates an equivalent spherical power (SE = S + 1 / 2C, hereinafter abbreviated as an SE value) based on the spherical power and the astigmatic power, and the drive signal of the moving mechanism 49 corresponding to the calculated SE value. (For example, the amount of movement from the reference position) is acquired from the memory 85. Then, the moving mechanism 49 is drive-controlled based on the acquired drive signal, and the lens 32 is moved to a position corresponding to the SE value of the subject's eye.

  For example, when the subject's eye is S = −3.0D and C = −2.0, SE = −4.0D, and the control unit 80 is disposed at a position (reference position) corresponding to 0D. The lens 32 is moved to a position corresponding to −4.0D. Note that the drive signal (for example, the number of pulses supplied to the pulse motor) of the moving mechanism 49 corresponding to the SE value is calculated in advance and stored in the memory 85.

  In the above configuration, the control unit 80 drives the drive mechanism 32c when the subject's eye is a refractive anomaly eye that exceeds a predetermined value, and drives the diopter correction lens corresponding thereto to the imaging optical path of the imaging optical system 30. Insert inside.

  When fundus imaging is performed with respect to a refractive error eye, the ring image when the lens 32 is in the initial position is largely blurred, and accurate image position detection is difficult. May occur. Therefore, when the control unit 80 moves the lens 32 to a position corresponding to the SE value, the controller 80 moves the moving mechanism 49 based on the image position data of the ring image without calculating the SE value of the subject's eye from the ring image. You may make it drive-control.

  Here, the control unit 80 specifies a meridian direction corresponding to an intermediate position between the major axis direction and the minor axis direction of the ring image, and the ring diameter in the identified meridian direction is a reference image (for example, a ring for a normal eye). The movement mechanism 49 is driven and controlled so as to match the ring diameter of the image. For example, if the major axis direction of the ring image is 0 degree and the minor axis direction of the ring image is 90 degrees, 45 degrees corresponds to the intermediate position. As described above, when the lens 32 is disposed at a position corresponding to the SE value, the control unit 80 stops driving the moving mechanism 49.

  Here, the control unit 80 combines the ring index image acquired by the two-dimensional light receiving element 167 with the subject eye observation image when the lens 32 is disposed at the focus end position, and displays it on the display monitor 8. . More specifically, the control unit 80 stores in the memory 85 a ring image acquired by the two-dimensional light receiving element 167 when the lens 32 is moved to a position corresponding to the equivalent spherical power of the subject's eye. The ring image R stored in the memory 85 is combined with the fundus observation image and displayed in a predetermined display area on the monitor 8 (see FIG. 2B). Thereby, the ring image acquired in a state where the lens 32 is disposed at the focus end position is displayed on the monitor 8 together with the fundus observation image.

  When the lens 32 is disposed at a position corresponding to the SE value, the refractive error in each meridian direction is corrected in a well-balanced manner. Therefore, a clear fundus image can be acquired even if the subject's eye is an astigmatic eye. However, when the astigmatism power of the subject's eye is large, even if the lens 32 is disposed at a position corresponding to the SE value, the amount of deviation between the fundus focus position in each principal meridian direction and the focus position of the SE value is large. Therefore, there is a possibility that a clear fundus image cannot be acquired and is blurred.

  Accordingly, by outputting the ring image acquired in the state where the focus adjustment is completed as described above to the monitor 8, the examiner can confirm the reliability of the focus adjustment, and accordingly, takes appropriate measures on the subject. be able to.

  For example, when the difference between the major axis and the minor axis of the ring image displayed on the monitor 8 is large, or when blurring in the major axis / minor axis direction of the ring image is conspicuous, the examiner has an astigmatism amount of the subject's eye. I can confirm it is big. Thus, the examiner operates the focus adjustment switch 84a so that a clear fundus image is displayed at a necessary portion (for example, a macular portion of the subject's eye) while viewing the fundus observation image displayed on the monitor 8. Such a thing can be considered. In the case of the ring image as described above, a fundus camera with an astigmatism correction function that performs astigmatism correction of the subject's eye using two cylindrical lenses having the same absolute value in order to reduce the burden on the subject's eye. It may be possible to recommend shooting at

  In addition, the image position information of the acquired ring image may be detected, and an electronic graphic corresponding to the detected image position information may be displayed. In this case, for example, an electronic graphic display imitating a ring index image acquired by the two-dimensional light receiving element 167 is displayed. As another method, the magnitude of the astigmatism power of the subject eye is measured by detecting the image position information of the ring image acquired by the two-dimensional light receiving element 167, and the astigmatism power of the subject eye is measured. It is conceivable to increase or decrease the indicator according to the size.

  More specifically, the control unit 80 acquires image position information in each meridian direction of the ring image received on the two-dimensional light receiving element 167, and a graphic imitating the ring image based on the acquired image position information The display of the monitor 8 is controlled so as to change the ring shape, color, brightness, thickness, etc. of the display.

  For example, the acquired ring image is binarized at a predetermined light amount level, a portion corresponding to a pixel region exceeding the predetermined light amount level is white, and a portion corresponding to a pixel region below the predetermined light amount level A method for indicating the color in black is conceivable. Further, the control unit 80 may perform an ellipse approximation process on the image position information of the ring image, and change the shape of the graphic display imitating the ring image based on the image position information after the ellipse approximation. Conceivable.

  When the ring image information acquired in the focus end state is displayed on the monitor 8, the lens 32 is moved from the focus end position (for example, the position corresponding to the SE value of the subject's eye), and the two-dimensional light receiving element. Even if the ring index image acquired by 167 changes, the ring index image acquired by the two-dimensional light receiving element 167 when the lens 32 is disposed at the focus end position or an electronic graphic display based on the ring index image is displayed. It is preferable to perform fixed display on the display monitor 8.

  More specifically, the control unit 80 acquires a ring image in a state where the position of the lens 32 is automatically adjusted by the autofocus control as described above, and displays the ring image on the monitor 8. Even if the lens 32 is moved by manual operation and the ring image received by the two-dimensional light receiving element 167 changes, the shape of the ring image is not changed accordingly. By performing such fixed display control, the ring acquired in a state of being arranged at an appropriate focus position (position corresponding to the SE value of the subject's eye) in which astigmatism of the subject's eye is corrected in a well-balanced manner The state where the image (ring image graphic) is displayed is maintained. Thereby, even when the lens 32 is moved from the predetermined focus end position, the examiner can grasp the reliability of the focus adjustment in the state where the lens 32 is arranged at the proper focus position. When the ring image acquired with the lens 32 moved from the focus end position is displayed on the monitor 8, the ring image is greatly blurred and placed in the proper focus position (position corresponding to the SE value). ), It is difficult to confirm the state of refractive error of the subject's eye.

  Here, after confirming the state of the subject's eye in the focus end state using the ring image displayed on the monitor 8, the examiner presses the photographing switch 84b to perform fundus photographing of the subject's eye. After the photographing is completed, the display on the monitor 8 is switched to a color fundus image photographed by the image sensor 35. The fundus image captured by the image sensor 35 is stored in the memory 85.

  In addition, after the fundus image of the subject's eye is captured as described above, the control unit 80 simultaneously displays on the monitor 8 the ring image acquired at the end of the focus in association with the acquired color fundus image. Output. As a result, the examiner can confirm the reliability of the focus adjustment in a state where the lens 32 is disposed at the focus end position from the ring image, and thus the sharpness of the fundus image that is difficult to understand from the fundus image displayed on the monitor 8. And the degree of blur can be predicted. That is, if the ellipticity of the ring image is large, it can be predicted that there is a high possibility that the fundus image is blurred due to a refractive error, and the examiner can perform appropriate processing.

  In the above configuration, when the captured color fundus image is transferred (output) to a personal computer on which predetermined electronic filing software is installed and the color fundus image is displayed on a large display provided in the personal computer, As described above, the ring image data acquired by the two-dimensional light receiving element 167 or graphic data imitating the ring image is transferred together in a format corresponding to the fundus image data, and is simultaneously displayed on the display together with the color fundus image. Also good. In this way, when the fundus image is observed on the electronic filing software, the cause of the fundus image can be identified from the ring image when the fundus image has low definition.

  In the state where the lens 32 is arranged at a position corresponding to the SE value of the subject's eye as described above, the control unit 80 is a lens arranged at a position corresponding to the equivalent spherical power of the subject's eye. The focus state with respect to the subject's eye fundus may be detected with reference to the movement position of 32, and the focus shift amount and the shift direction with respect to the subject's eye fundus may be electronically displayed on the monitor 8 (FIG. 5). reference). When detecting the focus state with respect to the fundus of the subject's eye based on the movement position of the lens 32 arranged at the position corresponding to the SE value of the subject's eye, the movement position corresponding to the SE value of the subject's eye By detecting the amount of movement of the lens 32 from the position, the focus shift amount and shift direction are electronically displayed on the monitor 8. In this case, as a detection mechanism for detecting the movement amount or movement position of the lens 32, a pulse motor is used as the drive motor of the movement mechanism 49, and the number of pulses supplied to the pulse motor based on the origin position set by a photosensor or the like. A configuration is conceivable in which the amount of movement of the lens 32 from the movement position corresponding to the equivalent spherical power of the subject's eye is obtained by measuring.

  In FIG. 5A, the indicator is increased or decreased in either plus or minus directions based on the equivalent spherical power SE according to the movement amount of the lens 32 from the position corresponding to the equivalent spherical power. It has become. Further, in FIG. 5B, the position of the lens 32 is replaced with the refractive power of the subject's eye, and the equivalent spherical power of the subject's eye is indicated in the gauge display in which the eye refractive power value is described. The movement amount of the lens 32 from the movement position corresponding to the equivalent spherical power of the subject's eye is displayed.

  Here, the examiner can focus on the observation site desired by the examiner while confirming the focus deviation amount and the deviation direction with the focus index (see FIG. 5) electronically displayed on the monitor 8. . Here, when the focus switch 84a is operated by the examiner from a state in which the indicator display indicates the equivalent spherical power SE, the indicator is increased or decreased according to the operation of the focus switch 84a.

  When electronically displaying the focus shift amount and shift direction with respect to the subject's fundus as shown in FIG. 5, the subject's fundus is based on the ring index image output from the two-dimensional light receiving element 167. It is also possible to detect the focus state with respect to and to display the focus shift amount and shift direction with respect to the fundus of the subject's eye based on the detection result. In this case, it is possible to detect a focus shift amount and a shift direction by detecting a change in the ring image with respect to the reference image (for example, detecting a focus shift amount and a shift direction from the size of the ring diameter with respect to the reference image).

  Note that the control unit 80 sets the focus position corresponding to the refractive power in the strong principal meridian direction of astigmatism of the subject's eye based on the ring index image acquired by the two-dimensional light receiving element 167 as the first focus limit position. Then, based on the ring index image acquired by the two-dimensional light receiving element 167, the focus position corresponding to the refractive power in the weak principal meridian direction of astigmatism of the subject's eye is set as the second focus limit position. Limit display corresponding to the first focus limit position and the second focus limit position may be performed on the display monitor.

More specifically, the control unit 80 measures the major axis and minor axis length of the ring image stored in the memory 85 in the electronic focus display shown in FIG. The refractive power corresponding to the major axis direction (weak principal meridian direction of subject's eye astigmatism) and the refractive power corresponding to the minor axis direction of the ring image (strong principal meridian direction of subject's eye astigmatism) are detected.
Here, the ring diameter in the major axis direction (weak main meridian direction) and minor axis direction (strong main meridian direction) of the ring image acquired at the focus end position is compared with the ring diameter in the reference image, and the reference The refractive power is obtained from the amount of deviation of the ring diameter with respect to the image. Here, the greater the amount of deviation with respect to the ring diameter of the reference image, the greater the degree of astigmatism, and the smaller the amount of deviation with respect to the ring diameter of the reference image, the smaller the degree of astigmatism. The magnitude of the astigmatism power of the subject's eye can be said to be a deviation amount of the refractive power with respect to the SE value (refractive power corresponding to the focus end position) of the subject's eye.

  Next, the control unit 80 sets the focus position corresponding to the refractive power in the strong principal meridian direction of the subject's eye astigmatism detected as described above as the first focus limit position, and the subject's eye astigmatism. A focus position corresponding to the refractive power in the weak main meridian direction is set as the second focus limit position. Then, the control unit 80 electronically displays on the monitor 8 a graphic display A1 corresponding to the first focus limit position and a graphic display A2 corresponding to the second focus limit position.

  In this case, the control unit 80 changes the display positions of the displays A1 and A2 with respect to the focus adjustment indicator according to the focus limit position set corresponding to the obtained refractive power. That is, the larger the astigmatism power of the subject's eye, the larger the width of the display A1 and the display A2, and the smaller the astigmatism power of the subject's eye, the smaller the range of the graphic displays A1 and A2. In this case, the control unit 80 may set the relationship between the refractive power of the subject's eye detected as described above and the display positions of the graphic displays A1 and A2 in advance.

  Here, since the examiner only has to operate the focus knob within a range where the indicator display can be accommodated between the graphic displays A1 and A2, the lens 32 is held within a range where the subject's eye is focused in a predetermined meridian direction. It can be moved easily. Therefore, the examiner corresponds to the weak principal meridian direction of the subject eye from the focus position corresponding to the strong principal meridian direction of astigmatism of the subject eye including the focus position corresponding to the equivalent spherical power of the subject eye. The lens 32 can be selectively moved up to the focus position, and an unnecessary focus operation can be avoided.

  In this case, the control unit 80 sets the movable range of the lens 32 by the moving mechanism 49 so as to move the lens 32 between the first focus limit position and the second focus limit position set as described above. You may make it restrict | limit. More specifically, when the movement position of the lens 32 moved based on the operation signal from the focus adjustment switch exceeds the focus limit position corresponding to the strong principal meridian direction of astigmatism of the subject's eye, When the focus limit position corresponding to the weak main meridian direction is exceeded, the control unit 80 stops driving the moving mechanism 49. That is, when the subject's eyes are astigmatic eyes, the control unit 80 determines between the focus position corresponding to the strong principal meridian direction of the subject's eyes and the focus position corresponding to the weak principal meridian direction of the subject's eyes. Then, the movable range of the lens 32 is set, and the movable range of the lens 32 is limited. In this way, it is possible to avoid moving the lens 32 beyond the range in focus with the subject's fundus in the predetermined meridian direction, and smooth focus adjustment can be performed.

  In the above description, a ring image acquired in a state where the focus adjustment for the subject's eye has been completed or an electronic graphic based on the ring image is displayed on the monitor 8, but the ring image information based on the ring image is used. If there is, it is not limited to this.

  For example, the control unit 80 determines the presence or absence of the astigmatism state of the subject's eye based on the ring index image acquired by the two-dimensional light receiving element 167 when the lens 32 is moved to the focus end position. The determination result may be displayed on the display monitor 8. Thereby, the reliability of focus adjustment can be determined.

  More specifically, the control unit 80 determines whether or not the astigmatism power of the subject's eye detected at the focus end position exceeds a predetermined allowable range, and displays the determination result on the monitor 8. In this case, when the absolute value of the astigmatism power of the subject's eye detected as described above is 1D or more, the control unit 80 notifies that the focus adjustment is low in the focus adjustment end stage. A message (for example, low reliability of focus, astigmatism in the subject's eye, possibility of low fundus image sharpness, etc.) or graphic is displayed on the monitor 8. On the other hand, when the absolute value of the astigmatism power of the subject's eye is smaller than 1D, a message is not displayed, or a message for notifying that the focus adjustment is highly reliable (for example, the focus reliability is high No astigmatism in the human eye, the fundus image is likely to be clear, etc.) or a graphic is displayed on the monitor. Further, when the astigmatism power of the subject's eye exceeds a predetermined allowable range, it is also conceivable to change the background color of the ring image or ring image graphic displayed on the monitor 8 (for example, from black Yellow).

  In the above description, a spot-like focusing light beam is projected onto the fundus of the subject's eye through the center of the pupil of the subject's eye, and the fundus reflection light flux is transmitted from the anterior eye portion of the subject to the ring index image. It is assumed that the two-dimensional light receiving element picks up the light as follows, but is not limited to this, and projects a ring-shaped light beam for focusing on the fundus of the subject's eye through the periphery of the pupil of the subject's eye, A ring image projected on the fundus of the subject's eye may be received by a two-dimensional light receiving element.

  In the above description, in the case of the fixation target presenting optical system 70 having a configuration (for example, Japanese Patent Application Laid-Open No. 2007-202724) capable of changing the present position of the fixation target that guides the line of sight of the subject's eye. When the fixation target presentation position is changed by the fixation target presentation optical system 70, the control unit 80 again controls the driving of the moving mechanism 49 based on the ring index image received by the two-dimensional light receiving element 167. Then, the lens 32 is moved, and the ring index image information acquired by the two-dimensional light receiving element 167 when the lens 32 is disposed at the focus end position is replaced with the ring index image information that has been displayed so far. Is preferably displayed. Here, by updating the ring index image information displayed on the monitor 8 in accordance with the change of the fixation target presentation position, the state of the subject's eye can be properly grasped. For example, when the fixation target presentation position is switched between the standard position for photographing the fundus central part and the peripheral position for photographing the fundus peripheral part, the refraction abnormality state of the subject's eye is substantially different (peripheral photographing) In this case, the angle of deviation between the optical axis of the subject's eye and the imaging optical axis L1 becomes large, and refraction abnormality is likely to occur), so that the ring image information corresponding to the new fixation target presentation position is updated. Thus, the examiner can appropriately notify the examiner of the change in the reliability of the focus adjustment that changes according to the fixation target presentation position.

  In the above description, when the movement mechanism 49 is driven and controlled based on the ring index image received by the two-dimensional light receiving element 167, the subject measured by an eye refractive power measuring device (auto reflex) in a separate housing. Measurement data including the astigmatism power of the eye (for example, the spherical power and the astigmatism power of the subject's eye) is acquired (for example, autoref measurement data is obtained via a LAN cable), and the lens is obtained using the acquired measurement data. The initial position of the lens 32 may be set by driving the lens 32 in advance to a moving position corresponding to the equivalent spherical power of the eye of the subject. In this case, the equivalent spherical power SE of the subject's eye can be calculated by SE = S + 1 / 2C using the spherical power S and the astigmatic power C of the subject's eye obtained by autoref.

  In this case, as an initial setting, the control unit 80 indicates that the focus adjustment has been performed by moving the lens 32 using the measurement data from the auto reflex (for example, focus adjustment based on the measurement data at the auto reflex has already been performed) or has already been focused. A message indicating that the adjustment has been completed is displayed on the monitor 8 as a reference display (for example, display of focus OK or the like). In the case of the above configuration, for example, when a predetermined setting is made by a predetermined switch arranged in the switch unit 84 and the ring image is received by the two-dimensional light receiving element 167, the moving mechanism 49 based on the ring image is used. The drive control is started. Further, the control unit 80 uses, as reference data, the ring index image information acquired by the two-dimensional light receiving element 167 when the lens 32 is arranged at the initial position by driving the lens 32 using the measurement data acquired from the auto reflex. You may make it display.

  In the above description, the position corresponding to the equivalent spherical power of the subject's eye is defined as the focus end position, but according to the examiner's preference, it corresponds to the refractive power in the strong principal meridian direction of the subject's eye. Or a position corresponding to the refractive power in the weak principal meridian direction of the subject's eye may be set as the focus end position.

It is a schematic block diagram of the optical system and control system of the fundus camera concerning this embodiment. It is a figure which shows the focus parameter | index projected on the subject eye fundus. It is a specific example which shows the movement range of the parameter | index projection optical system set according to the insertion / extraction state of a diopter correction lens. It is a schematic block diagram of the optical system and control system of the fundus camera which concerns on 2nd Embodiment. It is a figure in the case of displaying electronically the amount and direction of focus shift on a display monitor.

DESCRIPTION OF SYMBOLS 10 Illumination optical system 11 Observation light source 14 Imaging light source 25 Objective lens 30 Fundus observation / fundus imaging optical system 32 Focusing lens 32a, 32b Diopter correction lens 40 Focus index projection optical system 44 Polarization beam splitter 49 Moving mechanism 80 Control unit 140 Projection optical System 141 projection light source 160 light receiving optical system 167 two-dimensional light receiving element

Claims (1)

An illumination optical system having an illumination light source and illuminating the eye fundus of the subject via the objective lens with illumination light emitted from the illumination light source;
Fundus photography that has a focusing lens arranged so as to be movable in the direction of the optical axis, and receives the fundus reflected light from the illumination optical system through the objective lens and the focusing lens to photograph the fundus of the subject's eye A fundus photographing optical system in which a diopter correction lens for correcting the diopter of an eye having a refractive error of intensity is detachably arranged with respect to the optical path;
Focus detection optics having an index projection optical system having a projection light source and projecting a focus index onto the fundus of the subject's eye and a light receiving optical system having a light receiving element for receiving fundus reflected light by the index projection optical system The system,
A fundus camera comprising:
A movement mechanism having a drive unit and capable of moving a part of a focus detection optical system including at least one of the projection light source and the light receiving element in an optical axis direction, in which the diopter correction lens is inserted A moving mechanism having a movable range including a diopter correction range due to movement of the focusing lens at
Control means for controlling the driving of the drive unit in conjunction with the movement of the focusing lens, and when the diopter correction lens is inserted, depends on the inserted diopter correction lens and the moving position of the focusing lens. A fundus camera comprising: control means for moving a part of the focus detection optical system using the movement mechanism to a movement position corresponding to a diopter correction amount.

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