JP5879830B2 - Fundus imaging device with wavefront compensation - Google Patents

Description

  The present invention relates to a fundus imaging apparatus with wavefront compensation that captures a fundus image of a subject's eye while correcting the wavefront aberration of the subject's eye.

  An apparatus for detecting wavefront aberration of an eye using a wavefront sensor such as a Shack-Hartmann sensor, controlling a wavefront compensation device based on the detection result, and photographing a fundus image after wavefront compensation at a cellular level is disclosed ( For example, see Patent Document 1). Such an apparatus repeatedly detects the wavefront aberration of the eye and the wavefront compensation control based on the detection result after the alignment between the eye to be examined and the apparatus is completed.

JP-T-2001-507258

  However, after the alignment is completed, the fixation state of the eye to be examined is not sufficiently maintained, and a good fundus image may not be obtained.

  FIG. 6A is an example showing a light reception result of the wavefront sensor in a state where fixation is shifted. For example, the effective area 62 by the wavefront compensation device is set on the wavefront sensor, and the state of the wavefront is not detected in the area S where the Hartmann image 61 is not formed. As described above, when part of the wavefront measurement data is missing (see FIG. 6A), information on the entire wavefront cannot be obtained, and thus the wavefront aberration in the wavefront correction region is not properly measured. When wavefront compensation control is performed based on the detection result obtained in such a state, the wavefront compensation device is controlled with an incorrect aberration compensation amount.

  If the fixation is misaligned, the measurement must be interrupted and the position of the chin rest and forehead must be adjusted to readjust the alignment, so the examiner must always be concerned about this alignment. There was a lot of trouble.

  In view of the above problems, an object of the present invention is to provide a fundus photographing apparatus with wavefront compensation that can photograph a good fundus image in a state in which wavefront aberration is corrected.

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

(1) A fundus imaging optical system that has a scanning unit that scans light on the fundus of the subject's eye and receives reflected light from the fundus of the subject's eye to capture a fundus image, and an optical path of the fundus imaging optical system The wavefront compensation device is placed inside and controls the wavefront of the incident light to compensate the wavefront aberration of the eye to be examined. The measurement light is projected toward the fundus of the eye to be examined, and the reflected light from the fundus is detected by the wavefront sensor. A wavefront aberration measuring optical system, an effective area which is a part of a compensable area provided in the wavefront compensation device and in which aberration correction control is effective, and a wavefront measuring area where wavefront aberration is measured by the wavefront aberration measuring optical system And a control means for controlling the position of the effective area on the compensable area so that a deviation in a direction perpendicular to the optical axis is corrected, and a wider field angle than the fundus imaging optical system. First to capture the fundus image as the second fundus image A photographing unit, by controlling the scanning unit based on the position specified with the second fundus image, that and a photographing position control means for setting the imaging position on the fundus of the eye fundus photographing optical system Features.

  In view of the above problems, the present invention can capture a good fundus image in a state where wavefront aberration is corrected.

  An embodiment of the present invention will be described. FIG. 1 is an external view of a fundus imaging apparatus according to this embodiment, and the apparatus includes a base 510, a face support unit 600, and an imaging unit 500. The face support unit 600 is attached to the base 510. The imaging unit 500 houses an optical system described later, and is provided on the base 510. The face support unit 600 is provided with a chin rest 610. The chin rest 610 is moved in the left / right direction (X direction), the up / down direction (Y direction), and the front / rear direction (Z direction) with respect to the base of the face indicating unit 600 by operating a chin rest driving means (not shown).

  FIG. 2 is a schematic diagram showing an optical system of the fundus imaging apparatus of the present embodiment. The fundus imaging apparatus of the present embodiment is broadly divided into a fundus imaging optical system 100, a wavefront aberration detection optical system (hereinafter referred to as an aberration detection optical system) 110, aberration compensation units 10 and 72, and a second imaging. A unit 200 and a tracking unit (position detection unit) 300 are provided.

  The fundus imaging optical system 100 receives reflected light from the fundus of the eye E and captures a fundus image of the eye. The aberration detection optical system (aberration measurement optical system) 110 has a wavefront sensor 73, projects measurement light onto the fundus of the eye to be examined, and receives (detects) reflected light from the fundus as an index pattern image at the wavefront sensor 73. ) The aberration compensation units 10 and 72 are disposed in the fundus imaging optical system 100 in order to correct the aberration of the eye to be examined. The second photographing unit 200 displays a fundus observation image (hereinafter referred to as a second fundus image) for designating a photographing position of a fundus image obtained by the fundus imaging optical system 100 (hereinafter referred to as a first fundus image). obtain.

  Here, the fundus imaging optical system 100 captures the fundus of the eye E with high resolution (high resolution) and high magnification. The aberration compensation unit includes a diopter correction unit 10 for correcting low-order aberrations (diopter: for example, spherical power) of the eye to be examined, and a high-order aberration compensation unit for correcting high-order aberrations of the eye to be examined. (Wavefront compensation device) 72.

  The fundus imaging optical system 100 includes a first illumination optical system 100a that irradiates the eye E with illumination light (illumination light beam) to illuminate the fundus two-dimensionally, and reflected light (reflected light beam) of the illumination light irradiated on the fundus. And a first compensation optical system 100b for obtaining a first fundus image and an aberration compensator 72. The fundus imaging optical system 100 has, for example, a scanning laser ophthalmoscope configuration using a confocal optical system.

  The first illumination optical system 100 a includes a light source 1 (first light source) and a scanning unit 15. The light source 1 uses near-infrared illumination light that is difficult to be visually recognized by the eye to be examined, and emits illumination light for illuminating the fundus. In the present embodiment, the light source 1 is an SLD (Super Luminescent Diode) light source having a wavelength of 840 nm. The light source may be any light source that emits spot light having a high convergence property, and may be, for example, a semiconductor laser. The scanning unit 15 scans illumination light (spot light) in the horizontal direction (X direction) on the fundus.

  First, the first illumination optical system 100a will be described. The first illumination optical system 100a includes a lens 2, a polarizing beam splitter (PBS) 4, a concave mirror 6, a concave mirror 7, a plane mirror 8, a wavefront compensation device 72, and a concave mirror in the optical path from the light source 1 to the fundus. 11, a concave mirror 12, a scanning unit 15, a concave mirror 16, and a concave mirror 17. Further, the plane mirror 21, lens 22, plane mirror 23, diopter correction unit 10, plane mirror 25, concave mirror 26, deflection unit 400, dichroic mirror 90, concave mirror 31, plane mirror 32, plane mirror 33, concave surface A mirror 35 is arranged. The diopter correction unit 10 includes a plane mirror and a lens. The deflecting unit 400 scans the illumination light emitted from the light source 1 in the vertical direction (Y direction) on the fundus. Further, the deflecting unit 400 corrects the scanning position of the illumination light scanned in a two-dimensional manner. The dichroic mirror 90 makes the optical path of the second imaging unit 200 and the like substantially coaxial with the first illumination optical system 100a.

  The illumination light emitted from the light source 1 is converted into parallel light by the lens 2 and then passes through the PBS 4. In the present embodiment, the illumination light is changed to a light beam having only an S-polarized component by the PBS 4 in this embodiment. The illumination light that has passed through the PBS 4 is reflected by the concave mirror 6, the concave mirror 7, and the plane mirror 8 via the beam splitter (BS) 71, and enters the wavefront compensation device 72. The illumination light reflected by the wavefront compensation device 72 is reflected by the concave mirror 11 and the concave mirror 12 via the BS 75 and travels toward the scanning unit 15.

  Here, the scanning unit 15 scans illumination light in the X direction on the fundus. In the present embodiment, a resonant mirror serving as a deflecting member for deflecting and scanning illumination light in the horizontal direction (X direction) at the fundus and a drive unit for driving the mirror are provided. The illumination light that has passed through the scanning unit 15 is reflected by the concave mirror 16, the concave mirror 17, and the flat mirror 21 and is collected by the lens 22. The illumination light is reflected by the plane mirror 23. The illumination light is reflected by the plane mirror 25 and the concave mirror 26 via the diopter correction unit 10 and travels toward the deflection unit 400. The diopter correction unit 10 includes a driving unit 10a, and the optical path length can be changed by moving the plane mirror and the lens in the direction of the arrow shown in the drawing, and plays a role in diopter correction. The diopter correction unit 10 may be configured by a driving unit and a prism that can move in the optical axis direction by driving the driving unit.

  The deflecting unit 400 scans illumination light in the XY directions at the fundus. In this embodiment, the galvano mirror for X scanning and the galvano mirror for Y scanning are constituted by two galvano mirrors. The illumination light that has passed through the deflecting unit 400 is reflected by the dichroic mirror 90, the concave mirror 31, the flat mirror 32, the flat mirror 33, and the concave mirror 35, and is condensed on the fundus of the eye E to be scanned, and the scanning unit 15 and the deflecting unit. By 400, the fundus is scanned two-dimensionally.

  Further, the dichroic mirror 90 has a characteristic of transmitting a light beam from the second imaging unit 200 and tracking unit 300 described later and reflecting a light beam from the light source 1 and a light source 76 described later. Note that the emission ends of the light sources 1 and 76 and the fundus of the eye E are conjugate. Thus, the 1st illumination optical system 100a which irradiates illumination light to a fundus two-dimensionally is formed.

  The tracking unit 300 detects a time-dependent change in positional deviation due to fixation eye movement of the eye E to be photographed, and obtains movement position information. In the tracking unit 300, the light reception result obtained at the start of tracking is sent as reference information to the control unit 80, and thereafter, the light reception result (light reception information) obtained for each scan is sequentially transmitted to the control unit 80. The control unit 80 compares the received light information obtained thereafter with the reference information, and obtains the movement position information by calculation so that the same received light information as the reference information is obtained. The control unit 80 drives the deflection unit 400 based on the obtained movement position information. By performing such tracking, the deflection unit 400 is driven so that even if the eye E moves slightly, the movement of the eye E is offset, so that the movement of the fundus image displayed on the monitor 70 is suppressed. It becomes. The dichroic mirror 91 has a characteristic of transmitting the light beam from the second photographing unit 200 and reflecting the light beam from the tracking unit 300.

  Next, the first photographing optical system 100b will be described. The first photographing optical system 100 has a common optical path from the dichroic mirror 90 to the BS 71 described in the first illumination optical system 100a, and further includes a plane mirror 51, a PBS 52, a lens 53, a pinhole plate 54, a lens 55, and a light receiving element. 56. In this embodiment, the light receiving element 56 is an APD (avalanche photodiode). The pinhole plate 54 is placed at a position conjugate with the fundus.

  The reflected light from the fundus of the illumination light emitted from the light source 1 traces the first illumination optical system 100a in the reverse direction, is reflected by the BS 71 and the plane mirror 51, and only the S-polarized light is transmitted by the PBS 52. This transmitted light is focused on the pinhole of the pinhole plate 54 via the lens 53. The reflected light focused at the pinhole is received by the light receiving element 56 through the lens 55. Although a part of the illumination light is reflected on the cornea, most of the illumination light is removed by the pinhole plate 54, and the adverse effect of the corneal reflection on the image is reduced. For this reason, the light receiving element 56 can receive the reflected light from the fundus while suppressing the influence of corneal reflection.

  In this way, the first photographing optical system 100b is formed. The processed image received by the first imaging optical system 100b becomes the first fundus image. One frame of the first fundus image is formed by the main scanning of the scanning unit 15 and the sub scanning of the Y scanning galvanometer mirror provided in the deflection unit 400. Note that the deflection angle (swing angle) of the mirror in the scanning unit 15 and the deflection unit 400 is determined so that the angle of view of the fundus image (fundus image) acquired by the first imaging unit 100 becomes a predetermined angle. Here, in order to observe and photograph a predetermined range of the fundus at a high magnification (here, observation at a cell level or the like), the angle of view is set to about 1 to 5 degrees. In this embodiment, the angle is 1.5 degrees. Although depending on the diopter of the eye to be examined, the imaging range of the first fundus image is about 500 μm square.

  Further, the reflection angle of the X-scanning galvanometer mirror and the Y-scanning galvanometer mirror provided in the deflecting unit 400 is moved larger than the imaging field angle of the first fundus fundus image, so that the first fundus image on the fundus The imaging position is changed.

  Next, the second photographing unit 200 will be described. The second imaging unit is a unit for acquiring a fundus image (second fundus image) having a wider angle of view than the angle of view of the first imaging unit, and the acquired second fundus image has the narrow angle of view described above. Used for position designation and position confirmation for obtaining the first fundus image. The second imaging unit 200 for acquiring such a second fundus image only needs to be able to acquire the fundus image of the eye E to be examined in real time with a wide angle of view (for example, about 20 to 60 degrees). Therefore, the second imaging unit 200 can use an observation / imaging optical system of an existing fundus camera, an optical system of a scanning laser ophthalmoscope (SLO), and a control system.

  Next, the aberration detection optical system 110 will be described. As described above, the aberration detection optical system 110 has some optical elements on the optical path of the first illumination optical system 100a, and shares a part of the optical path with the first illumination optical system 100a. The aberration detection optical system 110 includes a light source 76, a lens 77, PBS 78, BS75, BS71, a dichroic mirror 86, PBS85, a lens 84, a plane mirror 83, a lens 82, and a wavefront sensor 73. The aberration detection optical system 110 is configured by sharing the optical members from the BS 71 to the concave mirror 35 placed on the optical path of the first illumination optical system 100a.

  The wavefront sensor 73 includes, for example, a microlens array composed of a large number of microlenses and a two-dimensional imaging element 73a (two-dimensional light receiving element) for receiving a light beam transmitted through the microlens array. A light source 76 that is an aberration detection light source (third light source) is a light source that emits light in an infrared region different from that of the light source 1. In the present embodiment, the light source 76 uses a laser diode that emits laser light having a wavelength of 780 nm.

  The laser light emitted from the light source 76 is converted into a parallel light beam by the lens 77, and the polarization direction (P-polarized light) is orthogonal to the illumination light from the light source 1 by the PBS 78, and is guided to the optical path of the first illumination optical system by the BS 75. Note that the emission end of the light source 76 has a conjugate relationship with the fundus conjugate position. The PBS 78 has a role of making the light emitted from the light source 76 a predetermined polarization direction, and has a role of a first polarization means provided in the wavefront compensation unit.

  The laser light reflected by the BS 75 is condensed on the fundus of the eye E through the optical path of the first illumination optical system 100a. The laser light reflected from the fundus is reflected by the wavefront compensation device 72 through each optical member of the first illumination optical system 100a, deviated from the optical path of the first illumination optical system 100a by the BS 71, and reflected by the dichroic mirror 86. The light is guided to the wavefront sensor 73 through the PBS 85, the lens 84, the flat mirror 83, and the lens 82.

  The PBS 85 is a second polarization unit provided in the wavefront compensation unit, blocks the polarization direction (P-polarized light) of the light emitted from the light source 76 to the eye E, and is orthogonal to the polarization direction (S-polarized light). Light) and guides it to the wavefront sensor 73. The dichroic mirror 86 has a characteristic of transmitting light (840 nm) having the wavelength of the light source 1 and reflecting light (780 nm) having the wavelength of the light source 76 for detecting aberration. Accordingly, the wavefront sensor 73 detects light having an S-polarized component from the scattered light on the fundus of the irradiated laser light. In this way, light reflected by the cornea and the optical element is suppressed from being detected by the wavefront sensor 73.

  The scanning unit 15, the reflection surface of the wavefront compensation device 72, and the microlens array of the wavefront sensor 73 are substantially conjugate with the pupil of the eye to be examined. The light receiving surface of the wavefront sensor 73 is substantially conjugate with the fundus of the eye E. As the wavefront sensor 73, an element capable of detecting wavefront aberration including low-order aberration and high-order aberration, for example, a Hartmann Shack detector, a wavefront curvature sensor that detects a change in light intensity, or the like is used.

  The wavefront compensation device 72 is, for example, a liquid crystal spatial light modulator and uses a reflective LCOS (Liquid Crystal On Silicon) or the like. The wavefront compensation device 72 is disposed in the optical path of the fundus imaging optical system 100 and controls the wavefront of incident light to compensate for the wavefront aberration of the eye to be examined. The wavefront compensation device 72 is a predetermined unit such as illumination light (S-polarized light) from the light source 1, reflected light from the fundus of the illumination light (S-polarized light), reflected light of wavefront aberration detection light (S-polarized component), and the like. Are arranged in a direction capable of compensating the aberration with respect to the linearly polarized light (S-polarized light). As a result, the wavefront compensation device 72 can modulate the S-polarized component of the incident light.

  The wavefront compensation device 72 has a predetermined direction in which the alignment direction of the liquid crystal molecules in the liquid crystal layer is substantially parallel to the polarization plane of the incident reflected light, and the liquid crystal molecules rotate according to a change in the voltage applied to the liquid crystal layer. Arranged so that the plane is substantially parallel to a plane including the incident optical axis and reflected optical axis of the reflected light from the fundus to the wavefront compensation device 72 and the normal of the mirror layer of the wavefront compensation device 72 Has been.

  In this embodiment, the wavefront compensation device 72 is a liquid crystal modulation element and uses a reflective LCOS (Liquid Crystal On Silicon) or the like, but is not limited thereto. Any reflective wavefront compensation device may be used. For example, a deformable mirror that is a form of MEMS (Micro Electro Mechanical Systems) may be used. Further, instead of a reflection type wavefront compensation device, a transmission type wavefront compensation device that transmits reflected light from the fundus and compensates for wavefront aberration can also be used.

  In the above description, a light source that emits illumination light having a wavelength different from that of the first light source is used as the aberration detection light source. However, the first light source may be used as the aberration detection light source.

  In the present embodiment described above, the wavefront sensor and the wavefront compensation device are the pupil conjugate of the eye to be examined. However, the position may be a position that is substantially conjugate with a predetermined part of the anterior eye portion of the eye to be examined. There may be.

  Next, a control system of the fundus imaging apparatus will be described. FIG. 3 is a block diagram showing a control system of the fundus imaging apparatus of the present embodiment. The control unit 80 that controls the entire apparatus includes a light source 1, a driving mechanism 505, a scanning unit 15, a light receiving element 56, a wavefront compensation device 72, a wavefront sensor 73, a light source 76, a second photographing unit 200, a tracking unit 300, The deflection unit 400 and the drive unit 10a are connected. Further, a storage unit 81, a control unit 92, an image processing unit 93, and a monitor 70 are connected.

  Based on signals received by the light receiving element 56 and the second imaging unit 200, the image processing unit 93 forms on the monitor 70 images of the fundus of the subject's eye with different angles of view, that is, a first fundus image and a second fundus image. Various setting information and captured images are stored in the storage unit 81. As the monitor 70, for example, a monitor of an external personal computer or a monitor provided in an apparatus can be considered. The monitor 70 displays fundus images (first fundus image and second fundus image) that are updated at a predetermined frame rate. The frame rate is, for example, 10 to 100 Hz. In this way, the fundus image is displayed as a moving image. In the present embodiment, the control unit 80 also functions as a display control unit of the monitor 70, a drive control unit of the deflection unit 400, and emission control units such as the light sources 1 and 76.

  When the wavefront compensation device 72 is controlled, the wavefront compensation device 72 is controlled based on the wavefront aberration detected by the wavefront sensor 73, and the illumination emitted from the light source 1 together with the S-polarized component of the reflected light of the light source 76. Higher order aberrations of the light and its reflected light are removed. In this way, the aberration of the illumination light emitted from the light source 1 and the reflected light is removed. In other words, a high-resolution first fundus image from which the high-order aberration of the eye E is removed (wavefront compensated) is obtained. In this case, the low-order aberration is corrected by the diopter correction unit 10.

  FIG. 4 is a diagram for explaining a compensable region and an effective region of the wavefront sensor. The compensable region 40 indicates a region where the wavefront of the incident light can be controlled in the wavefront compensation device 72. The effective area 41 indicates an area in which aberration correction is effective by feedback control of the wavefront compensation device 72 based on a detection signal from the wavefront sensor 73 in the compensable area 40. In the present embodiment, the compensable region 40 has a size of 16 × 12 mm, and the effective region 41 has a size of φ8.64 mm. Since the size of the compensable region 40 is sufficiently larger than the size of the effective region 41, at least one of the position, size, and shape of the effective region 41 can be changed in the compensable region 40 ( Details will be described later).

  FIG. 5 is a diagram for explaining a specific example of an index pattern image and an effective area on a compensable area of the wavefront sensor. FIG. 6 is a diagram showing an aberration correction screen 60 displayed on the screen of the monitor 70. The aberration correction screen 60 includes an index pattern image (in this embodiment, a Hartmann image, hereinafter referred to as a Hartmann image) 61 received by the two-dimensional imaging element 73a of the wavefront sensor 73, and a correction degree of aberration correction. An aberration correction graphic 65 that graphically displays (residual aberration) and a cell image image 66 of the fundus that is actually captured are displayed.

  A Hartmann image (dot pattern image) 61 represents a group of a plurality of point images 61 a received on the wavefront sensor 73. The fundus reflection light that has passed through the lens array is received by the two-dimensional imaging device 73a of the wavefront sensor 73 and captured as a Hartmann image. The Hartmann image 61 is displayed on the monitor 70. In the area where the point image 61a is detected by the wavefront sensor 73, aberration detection is possible.

  A circle 62 virtually indicates an effective region in which aberration correction is effective by the wavefront compensation device 72 on the two-dimensional imaging device 73a. The graphic corresponding to the circle 62 is superimposed on the Hartmann image on the monitor 70 and displayed. The mark located at the center of the circle 62 is a graphic indicating the center position of the effective area on the wavefront sensor 73.

  The outer circumference of the circle 62, the area, and the position information on the wavefront sensor 73 are set in the storage unit 81 in advance. These may be obtained in advance by calibration or simulation. In the wavefront compensation device 72, the effective region is limited to a light beam in a certain partial region (for example, a region having a diameter of 6 mm on the pupil) in the entire incident light. For this reason, other incident light is reflected toward the light receiving element 54, but the wavefront is not compensated.

  Here, the aberration correction is performed based on the aberration detection result by the wavefront sensor 73. That is, in the region where the Hartmann image 61 is formed in the region of the circle 62, the wavefront state can be detected (see FIG. 5B). On the other hand, in the region of the circle 62, the wavefront state is not detected in the region S where the Hartmann image 61 is not formed. Here, when part of the wavefront data is missing, information on the entire wavefront cannot be obtained, and therefore the wavefront aberration in the wavefront correction region is not properly measured (see FIG. 5A). Therefore, as shown in FIG. 6A, even when the aberration correction is performed, the aberration is not properly removed as shown in the aberration correction graphic 65. In addition, as shown in the cell image 66, it becomes difficult to capture.

  The operation of the fundus imaging apparatus having the above configuration will be described with reference to the flowchart shown in FIG.

  First, the examiner adjusts the position of the chin rest 610 manually or automatically while observing an anterior ocular segment image (not shown) displayed on the screen of the monitor 70 to perform rough alignment. Further, the examiner instructs the subject to fixate a fixation target (not shown).

  When the rough alignment by the chin rest 610 is completed and a measurement switch (not shown) is selected by the examiner, the control unit 80 performs diopter correction using the diopter correction unit 10, and then it is necessary for aberration correction. Perform wavefront detection.

  Next, the control unit 80 receives the effective area (for example, circle 62) of the wavefront compensation device 72 set on the wavefront sensor 73 and the light receiving area (wavefront measurement) of the index pattern image (for example, Hartmann image 61) by the wavefront sensor 73. The deviation information from the area is detected. Then, the controller 80 manually or automatically adjusts the position of the chin rest 610. As another configuration, when the photographing unit 500 is configured to be movable with respect to the eye E, the control unit 80 may move the photographing unit 500 so that the deviation information is within an allowable range.

  For example, the control unit 80 determines whether the region formed by the circle 62 is within the region formed by the Hartmann image outer periphery 61b. And the control part 80 adjusts the relative position of the eye E and the imaging | photography part 500, when the area | region which the circle | round | yen 62 comprises has remove | deviated from the area | region which the Hartmann image outer periphery 61b comprises. On the other hand, when the region formed by the circle 62 is within the region formed by the Hartmann image outer periphery 61b, the control unit 80 detects the wavefront aberration of the eye E based on the detection result of the wavefront sensor 73, and performs fundus imaging. Fundus photographing with the optical system 100 is started.

  The control unit 80 calculates an aberration compensation amount based on the detection result of the aberration, and controls the effective area 41 of the wavefront compensation device 72 using the calculation result to compensate the wavefront aberration. Then, the control unit 80 newly acquires a Hartmann image output from the wavefront sensor 73, and detects wavefront aberration. Then, an aberration compensation amount is calculated based on the aberration detection result, and the effective area 41 of the wavefront compensation device 72 is controlled using the calculation result to compensate for the wavefront aberration. As described above, the control unit 80 performs feedback control that repeats aberration detection and wavefront compensation control based on the aberration detection.

  For example, in the case of LCOS, compensation is performed in a loop process including detection of wavefront aberration by the wavefront sensor 73, calculation of an LCOS phase pattern based on the detection result, and application of a voltage to each pixel of the LCOS based on the calculation result. The phase pattern for use is feedback controlled. Accordingly, the refractive index of the LCOS liquid crystal layer is changed as needed based on the detection of the wavefront aberration, and the distortion of the wavefront of the fundus reflection light is corrected.

  In the case of a deformable mirror, a loop including wavefront aberration detection by the wavefront sensor 73, calculation of a mirror shape based on the detection result, and voltage application to each drive unit of the deformable mirror based on the calculation result. In the processing, the shape of the entire mirror is feedback controlled. Thereby, based on the detection of wavefront aberration, the shape of the entire mirror is changed as needed, and the distortion of the wavefront of the fundus reflection light is corrected.

  The above feedback control is reflected in the fundus moving image acquired simultaneously while the wavefront aberration is compensated. That is, as described above, by performing feedback control, the wavefront of the fundus reflection light is compensated, and thus blurring of the fundus moving image can be reduced. Therefore, a clear fundus image can be obtained even if the aberration state of the eye to be examined with respect to the fundus imaging apparatus changes due to changes in the fixation state or position of the eye to be examined.

  The feedback control is performed until the end of shooting. When a predetermined trigger signal is output while feedback control is performed and the fundus moving image is acquired, the cell image of the fundus acquired at that time is stored in the storage unit 81 as a moving image or a still image. Remembered.

  Here, even after the alignment is adjusted, for example, the fixation state of the eye E cannot be sufficiently maintained, so that a positional deviation occurs between the eye E and the apparatus, and the wavefront is actually measured. The wavefront measurement region (region formed by the Hartmann image outer periphery 61b) may deviate from the region necessary for controlling the effective region 41 (region formed by the circle 62) of the wavefront compensation device 72. In this case, sufficient wavefront information necessary for controlling the effective area 41 (area formed by the circle 62) cannot be obtained.

  Therefore, when a deviation occurs between the wavefront measurement region and the effective region of the wavefront compensation device, the control unit 80 measures the wavefront aberration by the effective region 41 in which the aberration correction control is effective in the wavefront compensation device 72 and the aberration measurement optical system 110. The wavefront compensation device 72 is controlled so that the deviation in the direction orthogonal to the optical axis between the measured wavefront measurement region and the wavefront measurement region is corrected. For example, the control unit 80 detects deviation information regarding a direction orthogonal to the optical axis between the effective area 41 and the wavefront measurement area. Then, the control unit 80 adjusts the position of the effective area 41 so that the deviation information is within the allowable range when the detected deviation information is out of the allowable range.

  Specifically, first, the control unit 80 sequentially detects the position of the point image received at the outermost side among the Hartmann images 61 received by the wavefront sensor 73, and obtains position information of the Hartmann image outer periphery 61b. To detect. Thereby, the detection area (wavefront measurement area) of the Hartmann image 61 is obtained.

  Next, the control unit 80 compares the position information of the Hartmann image outer periphery 61b and the position information of the circle 62 (effective region), and determines whether the wavefront measurement region satisfies the effective region based on the comparison result. Thereby, it is determined whether or not the aberration of the eye E can be corrected.

  More specifically, the control unit 80 compares the region surrounded by the Hartmann image outer periphery 61 b (see the dotted line) with the region surrounded by the circle 62. Here, the control unit 80 determines that it is sufficient (OK) when the region formed by the circle 62 is within the region formed by the Hartmann image outer periphery 61b (see FIG. 5B). Moreover, the control part 80 determines with it being inadequate (NG), when the area | region which the circle 62 comprises is not settled in the area | region which the outer periphery 61b comprises (refer Fig.5 (a)).

  If the controller 80 determines NG, the controller 80 controls the wavefront compensation device 72 so that the region formed by the circle 62 enters the region formed by the outer periphery 61b of the Hartmann image 61, and within the compensable region 40 of the wavefront compensation device 72. The effective area 41 is changed. Since the compensable region 40 is a region in which the wavefront of incident light can be controlled (moved, expanded, etc.), the effective region 41 is changed within the compensable region 64 by changing the position for controlling the wavefront of incident light. It is possible to change (reset).

  Hereinafter, a specific example of changing the effective area will be described with reference to FIG. For example, the control unit 80 calculates the center coordinate O1 of the Hartmann image 61 from the detected position information of the Hartman image outer periphery 61b. Further, the control unit 80 calculates the center coordinate O2 of the circle 62 (see FIG. 8A). The control unit 80 changes the control position of the wavefront of the wavefront compensation device 72 and moves the position of the effective region 41 so that the coordinate position of the center coordinate O1 of the Hartmann image 61 and the center coordinate O2 of the circle 62 coincide. As a result, as shown in FIG. 8B, the circle 62 is accommodated in the Hartmann image outer periphery 61a, and the aberration can be corrected. Further, as shown in FIG. 6B, the aberration is removed as shown in the aberration correction graphic 65, and an image from which the aberration is removed is also displayed in the cell image 66.

  Since the eye to be inspected may move at any time, the control unit 80 tracks the position of the effective area 41 of the wavefront compensation device 72 according to the change in the measurable area with respect to the measurement optical axis.

  As described above, with the adjustment of the position of the circle 62, the control unit 80 uses the aberration correction state used in the first effective area before adjusting the position, and adjusts the position after adjusting the position. 2. Aberration correction control in the effective area is performed. As the aberration correction control, the control unit 80 performs feedback control that repeatedly performs aberration detection and wavefront compensation control based on the detection result after adjustment to the second effective region. That is, the control unit 80 only needs to divert the aberration correction amount used in the effective region 41 before the position adjustment with respect to the aberration compensation amount in the effective region 41 after the position adjustment, and the aberration correction position while continuing the aberration correction amount. Correction processing is performed to change

  For example, when adjusting the position of the effective region 41, the control unit 80 causes the storage unit 81 to store the aberration compensation amount immediately before or before the region formed by the circle 62 deviates from the region formed by the Hartmann image outer periphery 61b. When the position adjustment of the circle 62 is completed, the control unit 80 operates the wavefront compensation device 72 with the aberration compensation amount stored in the storage unit 81. Of course, the aberration compensation amount may be maintained when the effective region is changed without storing the original aberration compensation amount. It is sufficient that the wavefront compensation device 72 is operated with an aberration compensation amount that reflects the aberration detection result before the region formed by the circle 62 deviates from the region formed by the Hartmann image outer periphery 61b, and the region formed by the circle 62 is the Hartman image. It is only necessary to apply a drive signal of the same level as before the region outside the outer periphery 61b.

  In the case of LCOS, the position of the effective region 41 is adjusted, and the control unit 80 determines the voltage application amount to each pixel of the LCOS in the effective region 41 so that the region formed by the circle 62 deviates from the region formed by the Hartmann image outer periphery 61b. The refractive index of LCOS may be made constant by adjusting the previous application amount. In the case of a deformable mirror, the control unit 80 similarly adjusts the voltage application amount to each drive unit with the application amount before the region formed by the circle 62 deviates from the region formed by the Hartmann image outer periphery 61b in the effective region. The shape of the entire mirror may be made constant.

  Note that the control unit 80 continuously acquires a high-magnification image of the fundus by operating the fundus imaging optical system 100 even when the deviation information is out of the allowable range, and the acquired high-magnification image is a moving image. An image is output to the monitor 85 as needed. That is, the control unit 80 performs tracking using the movement of the effective region position of the wavefront compensation device 72.

  After adjusting the position of the circle 62, the control unit 80 detects wavefront aberration by the wavefront sensor 73 and sends a drive signal based on the aberration detection result to the wavefront compensation device 72. The control unit 80 repeats the wavefront compensation operation by the wavefront compensation device 72 based on the aberration detection / detection result by the wavefront sensor 73 while the circle 32 is within the outer periphery 31a. Thereby, the aberration detection result detected in real time is reflected on the wavefront compensation device 72, and a good high-magnification fundus image with little blur is acquired.

  When wavefront aberration is compensated as described above and a predetermined trigger signal is output, a cell image of the fundus is captured as a moving image or a still image.

  During imaging, the Hartmann image 61 may deviate from the compensable region 64 of the wavefront compensation device 72 due to a significant shift in the position of the pupil of the eye to be examined. At this time, for example, by displaying a warning sound or indicating that the position of the eye to be examined is greatly deviated on the screen of the monitor 70, the examiner confirms that the position of the eye to be examined has been greatly deviated. Can be recognized. Then, in this case, the examiner adjusts the position of the jaw table (not shown) and coarsely aligns again to place the Hartmann image 61 in the compensable region 64 of the wavefront compensation device 72.

  According to the configuration as described above, even if aberration information of the eye E cannot be acquired due to a change in the pupil position of the eye to be examined, the shift of the measurement position is corrected, so that the minute region of the fundus is smoothly and satisfactorily You can shoot at. Further, it is not necessary for the examiner to always be aware of the alignment in preparation for a change in the pupil position of the eye to be examined, and the labor and burden on the examiner are reduced.

  Even when the position of the effective region is changed, the time required for the aberration correction is obtained by starting the aberration compensation feedback control using the aberration compensation amount of the wavefront compensation device 72 before the position of the effective region needs to be changed. Is less. Therefore, a good fundus image can be obtained smoothly.

  In the above determination, the control unit 80 determines that all point image position coordinates of the Hartmann image outer periphery 61b are outside or the same position as the position coordinates of the circle 62, and the area formed by the outer periphery of the Hartman image 61 is the outer periphery of the circle 62. If it is within the area to be formed, it may be determined as OK. In addition, the control unit 80 may determine that the position coordinates of the point image on the outer periphery of the Hartmann image 61 are NG when the position coordinates on the outer periphery of the circle 62 are on the inner side.

  In the above determination, the index pattern image does not have to satisfy 100% of the effective area, and the wavefront aberration may be measured with a certain accuracy (for example, 95% area). When a deviation is detected as a result of the determination, the control unit 80 controls the wavefront compensation device 72, and the index pattern image is received beyond a certain allowable range (for example, a certain ratio or more) in the effective region. The effective area is changed as follows.

  In this embodiment, the control unit 80 detects deviation information between the effective area of the wavefront compensation device 72 and the detection area of the fundus reflected light flux by the wavefront sensor 73 based on the output signal of the wavefront sensor 73. It is not limited. This apparatus detects deviation information regarding the direction orthogonal to the optical axis between the effective area of the wavefront compensation device 72 and the wavefront measurement area.

  For example, an observation optical system for observing a front image of the anterior segment of the eye to be examined is provided. The control unit 80 detects the pupil position from the front image of the anterior segment imaged by the observation optical system. And the control part 80 has the structure which detects the deviation information of the detected pupil position and the optical axis of the aberration detection optical system 110 as deviation information.

  As a means for detecting the pupil position, an effective region is set on the anterior ocular segment observation camera, and the control unit 80 performs image processing on the outer edge of the pupil from the front image of the anterior ocular segment imaged by the anterior ocular segment observation system. It is good also as a structure which detects a pupil position based on the said outer edge part extracted and extracted.

  Further, an alignment index projection optical system that projects alignment light onto the eye to be examined and forms an alignment index around the cornea, and an alignment index detection optical system that detects the alignment index formed around the cornea are provided. Note that the alignment detection result detected by the anterior ocular segment observation system is associated with the above-described deviation information in advance. And the control part 80 may be the structure which detects a pupil position indirectly based on the detection result by an alignment parameter | index detection optical system. In this case, for example, the pupil position is indirectly detected on the assumption that the corneal apex position detected by the alignment index is substantially the same as the pupil center position of the human eye.

  In the present embodiment, the effective amount is changed, and the compensation amount of the new effective region is changed to the aberration compensation amount in the original effective region. However, the present invention is not limited to this. For example, after changing the effective area, aberration detection may be started, and compensation may be started from the beginning.

  In the present embodiment, the control unit 80 maintains the aberration correction state before changing the effective area without resetting the aberration compensation amount in the effective area before changing the effective area to zero. May be.

  As a result, even when the effective area is restored to the position of the original effective area again, the driving amount and driving time of the wavefront compensation device 72 can be reduced, and a good fundus image can be obtained smoothly. Of course, after changing the effective area, the wavefront compensation device 72 may be reset to an initial state before starting the aberration detection.

  In the present embodiment, along with the change of the effective area, the aberration compensation amount of the wavefront compensation device 72 continuously performs feedback control after reflecting the aberration compensation amount before the deviation information is out of the allowable range. Although it was set as the structure, it is not limited to this.

  When the center of the measurable region deviates from the vicinity of the detection optical axis L1 of the aberration detection optical system 110, the control unit 80 moves the effective region 41 in which the aberration compensation has already been reflected, and temporarily stops the feedback control. You may do it. Furthermore, feedback control may be resumed when the center of the measurable region returns near the detection optical axis L1.

  For example, the control unit 80 causes the storage unit 81 to store the aberration compensation amount in the effective region 41 of the wavefront aberration compensation device 72 before the deviation occurs. Thereafter, when the center of the measurable area returns to the vicinity of the detection optical axis L1, the position of the effective area 41 is returned and the aberration compensation amount stored in the storage unit 81 is reflected in the wavefront compensation device 72.

  In the above description, the fundus imaging optical system 100 receives the light beam reflected from the fundus of the eye to be examined through the confocal aperture disposed at a position substantially conjugate to the fundus of the eye to be examined, and confocals the fundus of the eye to be examined. Although a confocal optical system (SLO optical system) that captures a front image is used, the present invention is not limited to this (see, for example, JP 2001-507258 A).

  For example, a fundus camera optical system that captures a frontal image of the fundus of the subject's eye by receiving a light beam reflected from the fundus of the subject's eye with a two-dimensional image sensor. Further, it may be an optical tomographic interference optical system (OCT optical system) that receives a light beam reflected from the fundus of the eye to be examined and interference light from the reference light and takes a tomographic image of the eye to be examined.

It is the figure which showed the external view of the fundus imaging apparatus of this embodiment. It is the schematic diagram which showed the optical system of the fundus imaging apparatus of this embodiment. It is the block diagram which showed the control system of the fundus imaging apparatus of this embodiment. It is a figure explaining the compensation area | region and effective area | region of a wavefront sensor. It is a figure explaining the specific example of the index pattern image and effective area on the compensation possible area | region of a wavefront sensor. It is the figure which showed the aberration correction screen displayed on the screen of a monitor. It is a flowchart explaining the operation | movement in the fundus imaging apparatus of this embodiment. It is a figure explaining the specific example of a change of an effective area | region.

DESCRIPTION OF SYMBOLS 1 Light source 10 Diopter correction part 15 Scan part 56 Light receiving element 72 Wavefront compensation device 73 Wavefront sensor 76 Light source 70 Monitor 80 Control part 81 Memory | storage part 100 Fundus imaging optical system 110 Wavefront aberration detection optical system 200 2nd imaging | photography unit 300 Tracking unit 400 Deflection unit 500 Imaging unit

Claims (1)

A fundus imaging optical system that has a scanning unit that scans light on the fundus of the subject's eye and that receives the reflected light from the fundus of the subject's eye and captures a fundus image;
A wavefront compensation device that is disposed in the optical path of the fundus imaging optical system and that controls the wavefront of incident light to compensate the wavefront aberration of the eye to be examined;
A wavefront aberration measuring optical system for projecting measurement light toward the fundus of the eye to be examined and detecting reflected light from the fundus by a wavefront sensor;
An optical axis between an effective region that is a part of a compensable region provided in the wavefront compensation device and in which aberration correction control is effective, and a wavefront measurement region in which wavefront aberration is measured by the wavefront aberration measurement optical system. Control means for controlling the position of the effective area on the compensable area so that the deviation in the orthogonal direction is corrected;
A second imaging unit that images a fundus image having a wider angle of view than the fundus imaging optical system as a second fundus image;
Photographing position control means for setting the photographing position on the fundus in the fundus photographing optical system by controlling the scanning unit based on the position designation using the second fundus image;
A fundus imaging apparatus with wavefront compensation, comprising: