JP5787060B2 - Fundus photographing device - Google Patents

Description

  The present invention relates to a fundus imaging apparatus for imaging the fundus of a subject's eye.

  2. Description of the Related Art Conventionally, a fundus imaging apparatus that captures the fundus of a subject's eye performs focusing on the fundus by moving a focusing lens in the optical axis direction so that a pair of split indexes projected onto the fundus matches. In addition, a device is known in which the fundus is automatically focused (autofocusing) by moving the focusing lens on the optical axis so that a pair of split indices detected in photographing match. (For example, refer to Patent Document 1).

JP 2009-183396 A

  The split index for focusing the fundus is projected at a position on the fundus that avoids the photographing optical axis in order to avoid the influence of harmful light caused by the objective lens (for example, vertically above the photographing optical axis). Projected to a position shifted in the direction). Therefore, when the focusing lens is moved on the optical axis to adjust the focus of the subject's eye, the projected angle of the split index on the fundus is changed with respect to the optical axis by changing the angle of view of the captured image ( (For example, in the vertical direction).

  On the other hand, it is difficult to detect the split index when the entire fundus is illuminated with infrared observation light. For this reason, in order to perform focusing with high accuracy, it is preferable that the detection range of the image sensor that captures the split index image is set narrow in advance. However, the narrower the detection range of the split index image on the image sensor, the higher the possibility that the split index image will be out of the detection range due to the influence of the angle of view change due to the movement of the focusing lens on the optical axis. .

  In view of the above-described problems of the prior art, the present invention is capable of setting a detection range of a split index image on an image sensor to be narrow and detecting a split index suitably regardless of a change in an angle of view according to a position of a focusing lens. An object of the present invention is to provide a fundus photographing apparatus capable of performing the above.

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

(1) A fundus illumination optical system for illuminating the fundus of the subject's eye, a split index projection optical system for projecting a pair of optical split indices onto the fundus, and a drive mechanism that moves in the optical axis direction A fundus photographing optical system including an imaging element in which a possible focusing lens is disposed in an optical path, and a split index image and a fundus image projected onto the fundus by the split index projection optical system; and an output of the imaging element Control means for detecting the separation state of the split index image from a signal, and driving the driving mechanism based on the detection result to move the focusing lens in the optical axis direction so as to focus the fundus. In the fundus imaging apparatus, a local area on the image sensor used for detecting the split index image is defined as the focusing lens. A storage unit that stores as detection range position information associated with the position of the lens, and the control unit is configured to detect the position on the image sensor based on the position of the focusing lens and the detection range position information stored in the storage unit. A detection range of the split index image at is set.

  According to the present invention, there is provided a fundus imaging apparatus that can set a narrow detection range of a split index image on an image sensor and can suitably detect a split index regardless of a change in an angle of view according to a position of a focusing lens. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an optical system and a control system of a fundus photographing apparatus (fundus camera). The optical system includes an illumination optical system 10, a fundus observation / imaging optical system 30 for observing and photographing the fundus of the subject's eye, and a split index projection for projecting a split index (focus index) onto the fundus of the subject's eye. Optical system 40, alignment index projection optical system 50 that projects an alignment index light beam onto the anterior segment of the subject's eye, anterior segment observation optical system 60 that captures the anterior segment of the subject's eye, and the subject's eye It is comprised from the fixation target presentation optical system 70 for guide | inducing the eyes | visual_axis of this.

  <Illumination Optical System> The illumination optical system 10 includes a photographing illumination optical system and an observation illumination optical system. The photographing illumination optical system includes a photographing light source 14 that emits a visible light beam, a condenser lens 15, a ring slit 17 having a ring-shaped opening, 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. The observation illumination optical system includes an illumination light source 11 that emits a near-infrared light beam, an infrared filter 12 that transmits near-infrared light, a condenser lens 13, and a dichroic disposed between the condenser lens 13 and the ring slit 17. The optical system includes a mirror 16, a ring slit 17 to a perforated mirror 22, a dichroic mirror (wavelength selection mirror) 24 as an optical path branching member, and an objective lens 25. The dichroic mirror 16 has a characteristic of reflecting infrared light and transmitting visible light. The dichroic mirror 24 has a wavelength characteristic that transmits a light beam having a wavelength of near infrared light from the infrared light source 11 of the observation illumination optical system and reflects infrared light from an alignment index projection optical system 50 described later. . The dichroic mirror 24 is obliquely provided in the optical path by an insertion / removal mechanism 66 including a solenoid and a cam during observation of the fundus using the observation illumination optical system, and the insertion / removal mechanism 66 when imaging the fundus using the imaging illumination optical system. Is removed from the optical path.

  <Fundus Observation / Shooting Optical System> The fundus oculi observation / shooting optical system 30 includes a fundus oculi observation optical system and a fundus photographic optical system. The fundus oculi observation optical system includes an objective lens 25, a dichroic mirror 24, a photographing aperture 31 located in the vicinity of the aperture of the perforated mirror 22, a focusing lens 32 movable in the optical axis direction, an imaging lens 33, and an insertion / removal mechanism at the time of fundus photographing. A flip-up mirror 34 that is removed from the optical path by 39 is provided. A dichroic mirror 37 having infrared reflection and visible light transmission characteristics, a relay lens 36, and a two-dimensional imaging device for observation having sensitivity in the infrared region are disposed in the optical path of the reflection mirror 34 in the reflection direction. A fundus image illuminated with an infrared light source is taken. The fundus photographing optical system shares the objective lens 25 and the optical system from the photographing aperture 31 to the imaging lens 33 with the fundus observation optical system. The fundus photographing optical system includes a photographing two-dimensional imaging element 35 having sensitivity in the visible range, and photographs a fundus image illuminated with a visible light source. The imaging 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.

  When observing the fundus, the luminous flux emitted from the illumination light source 11 passes through the dichroic mirror 24, and once converges in the vicinity of the pupil of the subject eye E by the objective lens 25, then diffuses to illuminate the fundus of the subject eye E. To do. Reflected light from the fundus passes through 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 dichroic mirror 37, and the relay lens 36. To form an image on the image sensor 38. At the time of photographing the fundus, reflected light from the fundus illuminated by the photographing light source 14 passes 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, and the two-dimensional image sensor. 35 is imaged.

  <Split index projection optical system> The split index projection optical system 40 includes an infrared light source 41, a slit index plate 42, two declination prisms 43 attached to the slit index plate 42, a projection lens 47, and an optical path of the illumination optical system 10. A spot mirror 44 is provided obliquely. The spot mirror 44 is fixed to the tip of the lever 45, and in a normal state, the lever 45 is placed on the optical axis so that the spot mirror 44 is positioned away from the optical axis. At the time of photographing, the lever 45 is retracted out of the optical path by the rotation of the shaft of the rotary solenoid 46. Thereby, the reflected light from the spot mirror 44 is projected to a position on the fundus that avoids the optical axis L1. Further, the spot mirror 44 is placed at a position conjugate with the fundus of the subject's eye E. The light source 41, the slit indicator plate 42, the deflection prism 43, the projection lens 47, the spot mirror 44, and the lever 45 are moved in the optical axis direction by the moving mechanism 49 in conjunction with the focusing lens 32.

  The luminous flux of the slit indicator plate 42 is separated by the deflection prism 43 and then reflected by the spot mirror 44 via the projection lens 47, and then passed through the relay lens 21, the perforated mirror 22, the dichroic mirror 24, and the objective lens 25. Then, it is projected onto the fundus of the subject's eye E. Here, it is assumed that the light flux of the slit target plate 42 is projected at a position slightly shifted upward from the position of the optical axis L1 (see FIG. 4). When the fundus is out of focus, the index images (split indices S1, S2) on the slit index plate 42 are separated and projected because they are not conjugate with the fundus. On the other hand, when the fundus is in focus, the split indexes S1 and S2 are in a conjugate relationship with the fundus, and thus are projected in agreement. The split indexes S1 and S2 projected on the fundus of the subject's eye E are imaged together with the fundus image by the image sensor 38.

  In the present embodiment, when the split index image (split index S1, S2) projected on the fundus is detected at least while the fundus is being observed, the split index is detected from the entire imaging surface of the image sensor 38. Rather than trying to detect an image, a detection region D that is locally set on the image sensor 38 is determined around the position where the split index is projected on the image sensor 38. As described above, the fundus is focused on the basis of the signal from the split index detection range D set on the image sensor 38. Further, by setting the detection range D of the split index on the image sensor 38 as narrow as possible, the influence of reflected light unnecessary for target detection such as noise light and illumination light included in the fundus image can be suppressed. The split index can be detected with high accuracy. It is also expected that the image processing speed will be increased by efficiently detecting the split index. A detailed description of the method for setting the detection range D will be given later.

  Here, FIG. 2 is an explanatory diagram of the focus state of the fundus indicated by the split index of the present embodiment. As shown in FIG. 2A, in a state where the split indicators S1 and S2 are separated, the upper split indicator S1 is previously placed on a reference line D1 (a corresponding line on the image sensor 38) that is a focus matching position. If the split index S2 is on the right side of the drawing (the left side of the reference line D1) than the set position, the focusing lens 32 is on the minus side of the matching position. On the other hand, as shown in FIG. 2 (b), when the split indicators S1 and S2 are separated and the split visual target S1 is on the left side of the paper with respect to the reference line D1 (the split indicator S2 is on the right side of the paper), focusing is performed. The lens 32 is on the plus side of the matching position. Further, as shown in FIG. 2C, when both of the split indexes S1 and S2 are in a straight line on the reference line D1, the focusing lens 32 is in the coincidence position. In other words, in addition to the presence / absence of split index matching, the split index separation direction is detected, whereby the movement amount and movement direction of the focusing lens 32 are determined.

  <Alignment Index Projection Optical System> In the alignment index projection optical system 50, a plurality of infrared light sources are arranged on a concentric circle centered on the photographing optical axis L1, and left and right across a vertical plane passing through the photographing optical axis L1. A first index projection optical system (0 degree and 180) having an infrared light source 51 and a collimating lens 52 disposed symmetrically, and a plurality of infrared beams disposed at positions different from the first index projection optical system. A second index projection optical system having a light source 53. 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. Project from a diagonal direction.

  <Anterior Eye Observation Optical System> The anterior eye observation optical system 60 includes a field lens 61 on the reflection side of the dichroic mirror 24, a mirror 62, a diaphragm 63, a relay lens 64, and a two-dimensional imaging device 65 having infrared sensitivity. Prepare. The anterior segment illuminated by the anterior segment illumination light source 58 is received by the two-dimensional imaging device 65 via the objective lens 25, the dichroic mirror 24, and the optical system from the field lens 61 to the relay lens 64. In addition, reflected light from the cornea of the alignment light beam by turning on the light source of the alignment index projection optical system 50 is detected by the two-dimensional image sensor 65. As a result, the pupil shape of the subject's eye is obtained from the anterior segment image captured by the two-dimensional imaging element 65, and the alignment state between the apparatus and the subject's eye is detected by photographing the alignment index.

  <Fixed Target Presenting Optical System> The fixed target presenting optical system 70 includes a visible light source 71, a fixed target switching member 72 capable of switching the formation position of the opening with respect to the optical axis L2, and a relay lens 73, and is dichroic. The optical path of the observation optical system 30 from the mirror 37 and the flip-up mirror 34 to the objective lens 25 is shared. Since the opening of the fixation target switching member 72 is selectively disposed in front of the visible light source 71, the fixation target is presented at a different position with respect to the optical axis L2, and standard imaging for imaging the fundus center The fixation position of the fixation target is changed between the peripheral photographing for photographing the fundus peripheral portion. The light beam that has passed through the fixation target switching member 72 passes through the relay lens 73, the dichroic mirror 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 fundus E is projected and fixation of the subject's eye is performed.

  <Control System> The control unit 80 controls various operations of the fundus imaging apparatus. The control unit 80 is connected to the above-described two-dimensional imaging elements, insertion / removal mechanisms, movement mechanisms, light sources, and the like. Further, a joystick 4 for manually moving the fundus imaging apparatus main body in the front-rear and left-right directions with respect to the subject's eye, and an imaging unit in which the above-described optical system and control system are provided are provided for the subject's eye. A driving unit 6 for moving in a three-dimensional direction, a monitor 8 for displaying an anterior ocular segment image and a fundus observation (imaging) image, an imaging switch 83 for inputting an imaging start trigger signal, and setting various conditions Are connected to the input switch 84 and the memory 85 as a storage unit. The memory 85 determines the position of the detection range of the image sensor 38 according to the position information of the detection range of the split index set in the image sensor 38 and the position of the focusing lens 32 on the optical axis L1. Position information and the like are stored.

  The control unit 80 detects the alignment index and the pupil shape P from the anterior segment image captured by the two-dimensional image sensor 65. Further, the control unit 80 obtains the alignment deviation amount of the imaging unit with respect to the subject's eye based on the imaging signal from the imaging element 65. Further, the control unit 80 causes the fundus image captured by the two-dimensional image sensor 38 to be displayed on the monitor 8 and focuses the fundus E based on the split index separation state obtained from the detection range set in the image sensor 38. And a process of determining the position of the detection range defined on the image sensor 38 as needed as the focusing lens 32 moves.

  Next, an operation of the fundus camera having the above configuration will be described. First, the examiner turns on the light source 71 of the fixation target presenting optical system 70 to fixate the subject's eye, and brings the imaging unit (not shown) closer to the subject's eye E by operating the joystick 4, The anterior segment image AE and the alignment index image are displayed on the monitor 8.

  FIG. 3 shows an example of the anterior segment image AE displayed on the monitor 8. Here, the state where alignment is in alignment is shown. When the alignment index image projected on the cornea of the subject's eye is detected by the image sensor 65, the control unit 80 XY of the center of the ring shape formed by the index images Ma to Mh projected in a ring shape. The coordinate is detected as a substantially corneal apex (alignment reference position) to display the alignment index A1 electronically, and the control unit 80 is a reference position in the X and Y directions set on the image sensor 65 in advance (for example, imaging) On the monitor 8 corresponding to the intersection of the imaging surface of the element 65 and the imaging optical axis L1, a mark A2 that serves as an alignment aim is electronically displayed. Further, the control unit 80 displays on the monitor 8 a reticle LT indicating the required pupil diameter with the display position of the mark A2 as the center.

  The control unit 80 drives the driving unit 6 so that the alignment deviation amount in the three-dimensional direction satisfies a predetermined alignment allowable range so that the mark A2 and the alignment index A1 match. The alignment in the working distance direction is confirmed by the indicator G displayed on the monitor 8, and when the number of indicators G is one, the state in which the working distance direction is aligned is confirmed.

  When the alignment is completed, the control unit 80 switches the display on the monitor 8 to the fundus image captured by the image sensor 38 and performs fundus focusing using the split index projection optical system 40. FIG. 4 shows an example of a fundus image displayed on the monitor 8. 4A shows a state where the fundus is out of focus, and FIG. 4B shows an enlarged view of the monitor 8 near the display positions of the split indicators S1 and S2. Yes. 4 shows the detection range D of the split indicators S1 and S2 set on the image sensor 38 for convenience (the detection range D is not displayed on the actual monitor 8).

  The detection range D of the present embodiment includes a reference line D1 for determining the match position of the split indices S1, S2, a boundary line D2 for determining the boundary position of the split indices S1, S2, and each split index for the reference line D1. It consists of detection ranges D3 and D4 set according to the movement range of S1 and S2. The detection ranges D3 and D4 are set so as to include a range in which the split indexes S1 and S2 are detected when the focusing lens 32 is moved within a movable range on the optical axis L1. The control unit 80 specifies the positions of the split indexes S1 and S2 based on the luminance distribution of the imaging range on the imaging device 38 corresponding to the detection ranges D3 and D4. Then, by obtaining the distance between the split indices S1 and S2 from the reference line D1 (or by obtaining the distance between the split indices), the separation state of the split indices S1 and S2 is obtained and focusing is performed. . When one of the split indicators S1 and S2 is set, the control unit 80 may perform focusing based on the distance between the detected split indicator and the reference line D1.

  By the way, the split index is projected on the fundus that avoids the optical axis L1 in order to avoid the influence of harmful light by the objective lens. On the other hand, when the focusing lens 32 is moved on the optical axis L1 for focusing, the angle of view (magnification) of the fundus image on the image sensor 38 changes. Therefore, the projection positions of the split indices S1 and S2 on the image sensor gradually shift from the detection range D set on the image sensor 38 in advance. Here, FIG. 5 shows a schematic diagram showing a positional relationship between the detection range D and the split indexes S1 and S2 when there is no position correction of the detection range D. FIG. 6 is a schematic diagram showing the positional relationship between the detection range D and the split indexes S2 and S2 when there is position correction of the detection range D.

  For example, when the focusing lens 32 is moved to the plus side from the reference position on the optical axis L1, the projection positions of the split indexes S1 and S2 are moved upward with respect to the detection range D as shown in FIG. Resulting in. On the other hand, when the focusing lens 32 is gradually moved to the minus side, the projection positions of the split indices S1 and S2 with respect to the detection range D are gradually moved downward. Then, as shown in FIG. 5B, when the split index S1 that should be detected in the detection range D3 originally enters the detection range D4 beyond the boundary line D2, the control unit 80 detects the detection range. There is a high possibility that the split index S1 detected at D4 is erroneously detected as the split index S2. Since the split index S1 is in the direction opposite to the split index S2 with respect to the reference line D1, the position of the focusing lens 32 on the optical axis L1 is erroneously determined, and the fundus is correctly focused. There is a high possibility that it will not be performed.

  Therefore, in the present embodiment, the position of the detection range D defined on the image sensor 38 is appropriately corrected by predicting the projection positions of the split indices S1 and S2 with respect to the position of the focusing lens 32. Here, a method for setting the detection range D will be described in detail. FIG. 7 is a flowchart for explaining an operation procedure of focusing according to the present embodiment. Here, a case where the same eye of the subject as in FIG. 5 is focused will be described.

  First, as initial setting, the position information of the detection range D of the image sensor 38 with respect to the position on the optical axis L1 of the focusing lens 32 is stored in the memory 85. The position information of the detection range D is the amount of movement of the projection positions (for example, S2) of the split indices S1 and S2 when the focusing lens 32 is moved on the optical axis L1 with respect to the normal eye (OD) ( Determined based on the number of pixels). For example, in the present embodiment, with the movement of the focusing lens 32, the split indicators S1, S2 are moved in the vertical direction along the reference line D1. Therefore, the detection range D on the image sensor 38 is also set so as to move in the vertical direction along the reference line D1. The control unit 80 corrects the position of the detection range D on the image sensor 38 based on the position information in the memory 85. Note that for such position correction of the detection range D, only the position of the reference detection range is stored in the memory 85, and the split of the shooting angle of view that changes depending on the amount of movement of the focusing lens 32 or the changed shooting angle of view. It is also possible to obtain the projection positions of the indices S1 and S2 by calculation, and obtain the position correction amount of the detection range D required by the calculation result.

  First, in step S101, the control unit 80 obtains the position of the focusing lens 32 on the optical axis L1 in a state where the alignment of the subject's eye is completed. Note that the position of the focusing lens 32 at the time of completion of alignment is an initial position set in advance in the apparatus or a focus coincidence position of the subject's eye photographed last time. Next, in step S <b> 102, the control unit 80 sets a detection range D on the image sensor 38 based on the position of the focusing lens 32 on the optical axis L <b> 1 and the position information stored in the memory 85. Accordingly, as shown in FIG. 6A, the detection range D is set in accordance with the projection positions of the split indexes S1 and S2.

  Next, in step S103, the control unit 80 detects the coincidence state of the split indicators S1 and S2 based on the information from the detection range D. If the split indicators S1 and S2 are separated, the process proceeds to step S104. On the other hand, if the split indices S1 and S2 match, the process moves to step S105 to complete the focusing.

  In step S104, the control unit 80 moves the focusing lens 32 on the optical axis L1 so that the split indexes S1 and S2 match, and then returns to step S101. When the focusing lens 32 is moved on the optical axis L1, as shown in FIG. 6B, the projection positions of the split indexes S1 and S2 are shifted downward. If the position on the optical axis L1 after the movement of the focusing lens 32 is obtained in step S101, the detection range D of the image sensor 38 is reset in step S102. As a result, as shown in FIG. 6B, even if the projection positions of the split indices S1 and S2 change with the movement of the focusing lens 32, the detection range D matches the projection positions of the split indices S1 and S2. Since it is set, autofocusing is continued with high accuracy. Similarly, in step S103, the coincidence state of the split indicators S1 and S2 is detected. Then, as shown in FIG. 6C, the control unit 80 repeats the processing from step S101 to S104 at predetermined time intervals until it is determined that the split indexes S1 and S2 match. At the same time, the control unit 80 corrects the position of the detection range D at any time or at a predetermined interval (time or focusing lens position) in accordance with the projection position of the split indexes S1 and S2 that change as the focusing lens 32 moves. Go. As a result, the split indicators S1 and S2 are preferably repeatedly detected until the split indicators S2 and S2 match.

  As described above, the control unit 80 sets the detection range D according to the preset indices S1 and S2 whose projection positions are changed by the change in the angle of view caused by the movement of the focusing lens 32. Can follow the split indexes S1 and S2 to which the lens is moved, so that focusing can be performed with high accuracy.

  That is, in the case where the position correction of the detection range D in FIG. 5 is not performed, if the projection positions of the split indicators S1 and S2 are moved in the vertical direction by focusing, the projection position of the split indicator is deviated from the detection range D. Therefore, accurate focusing cannot be performed. On the other hand, in the case where the position of the detection range D in FIG. 6 is corrected, even if the projection positions of the split indicators S1 and S2 move up and down due to focusing, the detection range follows the projection positions of the split indicators S1 and S2. Since D is reset, the control unit 80 can perform focusing with high accuracy based on information from the image sensor 38.

  When the photographing switch 83 is pressed in a focused state, the control unit 80 photographs the dichroic mirror 24 and the flip-up mirror 34 by driving the insertion / removal mechanism 39 and the insertion / removal mechanism 66 by the trigger signal. While removing from the optical axis L1, the visible light source of the fundus photographing optical system is turned on. Reflected light from the fundus E illuminated with a visible light beam is received by the two-dimensional imaging device 35 via the objective lens 25 and the optical system from the imaging aperture 31 to the imaging lens 33. The control unit 80 causes the memory 85 to store a captured image obtained by imaging with the two-dimensional imaging element 35. Further, after the fundus photography is completed, the control unit 80 inserts the dichroic mirror 24 and the flip-up mirror 34 into the optical path, and causes the monitor 8 to display the anterior segment image.

The configuration of the present invention is not limited to this. Any configuration may be used as long as the setting position of the detection range D set in the image sensor 38 is appropriately corrected in accordance with the position of the split index whose projection position changes as the focusing lens moves.
For example, in a state where the anterior eye portion imaged by the anterior eye portion observation optical system 60 is displayed on the monitor 8 (in a state where alignment is performed), the luminance of the light source 11 of the fundus observation illumination optical system is reduced. (Or in a state where the light is extinguished), an image of the split index is taken by the image sensor 38. At this time, since the luminance of the fundus is set low (it is dark), the influence of the reflected light from the fundus is small (no). Therefore, the split index can be detected by setting the detection range D wide or using the entire image sensor 38 for the split index detection. Needless to say, the split index can be detected using the narrow detection range D as described above. At this time, the position of the split index may be more easily detected by performing control such as blinking of the split index by the control unit 80.

  Then, the control unit 80 sets the detection range D in the image sensor 38 in correspondence with the projected position of the split index detected by the image sensor 38, and predicts the match position of the split index in advance so that the split is performed. The driving amount of the focusing lens 32 required for achieving the matching state is obtained. Further, the driving amount of the driving mechanism 49 for moving the focusing lens 32 and the moving amount of the pixel in the detection range D on the image sensor 38 are associated in advance. In this way, the detection range D is set corresponding to the projection positions of the split indices S1 and S2, and the focusing is performed with high accuracy.

  In the above description, the case where the fundus focusing is automatically performed (autofocus) has been described as an example. However, the configuration of the present invention may be applied when the examiner manually performs focusing. For example, when displaying an electronic focus index on a monitor based on the detection state of an optical split index, a local detection range for detecting the split index is set on the image sensor 38 and a focusing lens is set. The position of the detection range is corrected according to the position of 32. In this way, the split index is detected with high accuracy, and the electronic focus index is preferably displayed on the monitor.

It is a schematic block diagram of the optical system and control system of a fundus imaging apparatus. It is explanatory drawing of the focus state of a fundus. It is an example of the anterior segment image displayed on a monitor. It is an example of the fundus oculi image displayed on the monitor. It is explanatory drawing of the relationship between the detection range in case there is no position correction, and a split parameter | index. It is explanatory drawing of the relationship between the detection range in case there exists position correction, and a split parameter | index. It is a flowchart for demonstrating the operation | movement procedure of focusing.

DESCRIPTION OF SYMBOLS 10 Illumination optical system 30 Fundus observation / imaging optical system 32 Focusing lens 35, 38, 65 Two-dimensional image sensor 40 Split index projection optical system 41 Light source 49 Drive mechanism 50 Alignment index projection optical system 60 Anterior eye observation optical system 70 Fixation Marking optical system 80 Control unit 85 Memory

Claims (3)

A fundus illumination optical system for illuminating the fundus of the subject's eye;
A split index projection optical system that projects a pair of optical split indexes on the fundus;
A fundus photographing optical system comprising: a focusing lens that is movable in the optical axis direction by a drive mechanism, disposed in an optical path, and an image sensor that captures a split index image and a fundus image projected onto the fundus by the split index projection optical system The system,
Control for detecting the separation state of the split index image from the output signal of the image sensor, and driving the driving mechanism based on the detection result to move the focusing lens in the optical axis direction to perform focusing on the fundus Means,
A fundus photographing apparatus comprising:
A storage unit for storing a local area on the image sensor used for detection of the split index image as detection range position information associated with a position of the focusing lens;
The fundus imaging is characterized in that the control means sets a detection range of the split index image on the imaging device based on the position of the focusing lens and the detection range position information stored in the storage unit. apparatus. The fundus imaging apparatus according to claim 1,
The detection range position information is a projection position of the split index image based on a change in an angle of view with respect to the subject's eye when the position of the focusing lens is moved on the optical axis with respect to the subject's eye with a normal eye. The fundus photographing apparatus is determined based on a movement amount of the fundus. The fundus imaging apparatus according to claim 1 or 2,
Having an anterior ocular segment observation optical system for receiving an anterior ocular segment observation image by receiving reflected light from the anterior ocular segment illuminated with infrared light emitted from a light source;
In the state where the anterior ocular segment observation image is displayed on the monitor, the control means does not illuminate the fundus by the fundus illumination optical system or attenuates the split index image by the split index projection optical system in a attenuated state. The fundus photographing apparatus is characterized in that the detection range is set by calculating the light receiving position of the split index image on the image sensor by performing projection of the above.