JP2012095924A - Fundus photographing apparatus with wavefront compensation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To capture a favorable fundus image with corrected wavefront aberration.SOLUTION: A fundus photographing apparatus includes: a fundus photographing optical system; a wavefront compensating device disposed in an optical path of the fundus photographing optical system, controlling a wavefront of incident light and compensating the wavefront aberration of a subject's eye; a wavefront aberration detecting optical system projecting measuring light towards the fundus oculi of the subject's eye and detecting the reflection light from the fundus oculi by a wavefront sensor; a detecting means for detecting deviation information between a compensable region of the wavefront compensating device that is set on the wavefront sensor and a detecting region of a fundus reflection optical flux by the wavefront sensor; and a control means performing a feedback control for repeating the detection of the wavefront aberration of the subject's eye based on the detection signal from the wavefront sensor and a control of the wavefront compensating device based on the detection result, when the deviation information detected by the detection means goes outside a tolerance, temporarily stopping the feedback control and, when the deviation information is returned to a range within the tolerance, restarting the feedback control.

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. 4A is an example showing a light reception result of the wavefront sensor in a state where fixation is shifted. For example, the wavefront compensation region 32 by the wavefront compensation device is set on the wavefront sensor, and the state of the wavefront is not detected in the region S where the Hartmann image 31 is not formed. As described above, when part of the wavefront measurement data is missing (see FIG. 4A), 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.

  Even if the loss of the wavefront measurement data is resolved, it takes time to return the wavefront compensation device controlled with an incorrect aberration compensation amount to an appropriate control state, and the observation of a good fundus image is resumed. It took a lot of time (for example, about 3 seconds).

  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 receives reflected light from the fundus of the subject's eye and picks up a fundus image, and a wavefront aberration of the eye to be examined by controlling the wavefront of incident light that is disposed in the optical path of the fundus imaging optical system. A wavefront compensation device that compensates for, a wavefront aberration detection optical system that projects measurement light toward the fundus of the subject's eye and detects reflected light from the fundus using a wavefront sensor, and the wavefront that is set on the wavefront sensor Detection means for detecting deviation information between the compensation area of the compensation device and the detection area of the fundus reflected light beam by the wavefront sensor, detection of wavefront aberration of the subject's eye based on a detection signal from the wavefront sensor, and detection thereof Control means for performing feedback control that repeats control of the wavefront compensation device based on the result, and feedback control when the deviation information detected by the detection means is out of an allowable range Is temporarily stopped, and feedback control is resumed when the deviation information returns to within an allowable range.
(2) The fundus imaging apparatus according to (1) is characterized by comprising display means for outputting a fundus image continuously captured by the fundus imaging optical system as a moving image.
(3) The fundus imaging apparatus according to (2), further comprising position adjustment means for relatively adjusting a positional relationship between the detection optical system and the eye to be inspected so that the deviation information is within an allowable range. And
(4) In the fundus imaging apparatus according to (3), when the control unit stops the feedback control, the aberration compensation amount by the wavefront aberration compensation device is the aberration compensation amount before the deviation information is out of the allowable range. Hold on.
(5) The fundus imaging apparatus according to (3), further comprising storage means for storing wavefront control information of the wavefront compensation device, wherein the control means controls the wavefront when the deviation information is within an allowable range. Information is stored in the storage means, and the wavefront control information of the wavefront compensation device is reflected in the wavefront compensation device when the deviation information returns within an allowable range.

  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 shows an external view of a fundus imaging apparatus according to the present embodiment, and this apparatus is movable on a base 21, a face support unit 20 attached to the base 21, and the base 21. A driving mechanism 505 including a provided motor and the like, and an imaging unit 500 that houses an optical system described later on the driving mechanism 505 are provided. The drive mechanism 505 is moved on the base 21 in the left-right direction (X direction), the up-down direction (Y direction), and the front-rear direction (Z direction) by operation of a joystick or the like (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 wavefront aberration detection optical system includes a wavefront sensor 73, projects measurement light onto the fundus of the eye to be examined, and receives reflected light from the fundus as an index pattern image. 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. 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.

  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 100a includes a light source 1 (first light source) that emits illumination light for illuminating the fundus and a scanning unit 15 that two-dimensionally scans the illumination light (spot light) on the fundus. The light source 1 emits near-infrared illumination light that is hardly visible to the eye to be examined. 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.

  First, the first illumination optical system 100a will be described. In the optical path from the light source 1 to the fundus, a lens 2, a beam splitter 3, a polarizing plate 4, a lens 5, a beam splitter 71, a lens 6, a wavefront compensation device 72, a lens 7, and a beam splitter 75 are arranged. Further, the lens 8, the scanning unit 15, the lens 9, the deflection unit 400 for correcting the scanning position of the illumination light scanned two-dimensionally, the diopter correction unit 10 composed of two prisms, the lens 11, 2 A beam splitter 90 is disposed so that the optical path of the photographing unit 200 or the like is substantially coaxial with the first illumination optical system. The beam splitter 3 is a half mirror in this embodiment.

  Illumination light emitted from the light source 1 is converted into parallel light by the lens 2 and then converted into a light beam of only the S-polarized component by the polarizing plate 4 in this embodiment via the beam splitter 3. The illumination light that has passed through the polarizing plate 4 is once condensed by the lens 5, converted into a parallel light beam by the lens 6 through the beam splitter 71, and enters the wavefront compensation device 72. The illumination light reflected by the wavefront compensation device 72 is relayed by the lens 7 and the lens 8 and travels toward the scanning unit 15.

  The scanning unit 15 is configured to scan illumination light two-dimensionally on the fundus, and here, as illustrated, scans illumination light in the XY 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) on the fundus, and scanning by deflecting the illumination light in a direction perpendicular to the horizontal scanning direction (Y direction). A galvanometer mirror serving as a deflection member and a drive unit for driving each mirror. The illumination light that has passed through the scanning unit 15 is condensed again by the lens 9. The deflecting unit 400 has a function of further deflecting the illumination light having passed through the scanning unit 15 by a predetermined amount with respect to the horizontal direction and the vertical direction, and is configured by two galvanometer mirrors in the present embodiment. The illumination light that has passed through the deflection unit 400 is condensed on the fundus of the eye E through the diopter correction unit 10, the lens 11, and the beam splitter 90, and is scanned two-dimensionally on the fundus by the scanning unit 15. The diopter correction unit 10 includes a drive unit 10a, and one prism moves in the direction of the arrow shown in the figure, so that the optical path length can be changed and plays a role in diopter correction. The diopter correction unit 10 may be configured by a driving unit and a lens that can move in the optical axis direction by driving the driving unit. In addition, the beam splitter 90 is a dichroic mirror in the present embodiment, and reflects the light beam from the second imaging unit 200 and tracking unit 300 described later, and transmits the light beam from the light source 1 and the light source 76 described later. have. Note that the emission ends of the light source 1 and the light source 76 and the eye E to be examined are conjugate. In this way, the first illumination optical system that irradiates the fundus with illumination light two-dimensionally is formed.

  Next, the first photographing optical system 100b will be described. The first photographing optical system 100 has a common optical path from the beam splitter 90 to the beam splitter 3 described in the first illumination optical system 100a, and further includes a lens 51, a pinhole plate 52 placed at a position conjugate with the fundus, and a light collecting unit. An optical lens 53 and a light receiving element 54 are included. In this embodiment, the light receiving element 54 is an APD (avalanche photodiode).

  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 and is transmitted by the polarizing plate 4 only for S-polarized light, and then partially reflected by the beam splitter 3. Is reflected. This reflected light is focused on the pinhole of the pinhole plate 52 through the lens 51. The reflected light focused at the pinhole is received by the light receiving element 54 through the lens 53. Although a part of the illumination light is reflected on the cornea, most of the illumination light is removed by the pinhole plate 52, and the adverse effect of the corneal reflection on the image is reduced. For this reason, the light receiving element 54 can receive reflected light from the fundus while suppressing the influence of corneal reflection. The beam splitter 3 may be a hall mirror. In this case, the hole of the Hall mirror suppresses the corneal reflection light from entering the first imaging optical system 100b.

  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. Note that the mirror swing angle (swing angle) in the scanning unit 15 is determined so that the angle of view of the fundus image (fundus image) acquired by the first photographing unit 100 is 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.

  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 wavefront sensor 73, a polarizing plate 74, a light source 76, a lens 77, a polarizing plate 78, and a lens 79. From the beam splitter 71 to the beam splitter 90 placed on the optical path of the first illumination optical system. These optical members are shared. The wavefront sensor 73 includes, for example, a microlens array composed of a number of microlenses and a two-dimensional imaging element 73a (two-dimensional light receiving element) for receiving a light beam that has passed 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 polarizing plate 78, and the optical path of the first illumination optical system by the beam splitter 75. Led to. Note that there is a fundus conjugate position between the lenses 7 and 8, and the emission end of the light source 76 has a conjugate relationship with this fundus conjugate position. The beam splitter 75 is a half mirror in this embodiment. The polarizing plate 78 has a role of making the light of the third light source irradiated to the fundus a predetermined polarization direction, and has a role of a first polarizing means provided in the wavefront compensation unit.

  The laser beam reflected by the beam splitter 75 is condensed on the fundus of the eye E through the optical path of the first illumination optical system 100a. The laser beam 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 beam splitter 71, the lens 79, and S-polarized light. The light is guided to the wavefront sensor 73 through the polarizing plate 74 through which only the component passes. The polarizing plate 74 is a second polarization unit provided in the wavefront compensation unit, and blocks the polarization direction (P-polarized light) of the light of the third light source irradiated to the fundus and is polarized perpendicular to the polarization direction. It plays the role of transmitting the direction (S-polarized light) and guiding it to the wavefront sensor 73. Note that the beam splitter 71 transmits light (840 nm) having the wavelength of the light source 1 and reflects 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. Further, the wavefront compensation device 72 has a liquid crystal molecule arrangement direction in the liquid crystal layer substantially parallel to the polarization plane of the incident reflected light, and the liquid crystal molecules rotate in accordance with a change in voltage applied to the liquid crystal layer. The predetermined surface is substantially parallel to a plane including the incident optical axis and the 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. Have been placed.

  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 54, 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, the deflection unit 410, and the diopter correction unit 10 are connected. A storage unit 81, a control unit 82, an image processing unit 83, and a monitor 85 are connected.

  The image processing unit 83 forms, on the monitor 85, images of the fundus oculi having different angles of view, that is, a first fundus image and a second fundus image, based on signals received by the light receiving element 54 and the second imaging unit 200. Various setting information and captured images are stored in the storage unit 81. As the monitor 85, for example, a monitor of an external personal computer or a monitor provided in an apparatus can be considered. The fundus images (first fundus image and second fundus image) updated at a predetermined frame rate are displayed on the monitor 85. 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 the display control unit 80 of the monitor 85, the drive control unit 80 of the deflection units 400 and 410, and the emission control unit 80 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.

<Description of index pattern image and compensation area>
FIG. 4 is a diagram for explaining a specific example of the index pattern image on the wavefront sensor 73 and the compensable region. FIG. 5 is a diagram showing the aberration compensation screen 40 displayed on the screen of the monitor 85. On the aberration compensation screen 40, the index pattern image received by the two-dimensional image sensor 73a of the wavefront sensor 73 (in this embodiment, a Hartmann image, hereinafter referred to as a Hartmann image) and the correction degree of the aberration compensation are displayed. An aberration compensation graphic 41 displayed graphically is displayed.

  A Hartmann image (dot pattern image) 31 represents a group of a plurality of point images 31 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 31 is displayed on the monitor 85. In the region where the point image 31a is detected by the wavefront sensor 73, aberration detection is possible.

  A circle 32 virtually indicates a region in which aberration compensation can be performed by the wavefront compensation device 72 on the two-dimensional image sensor 73a. The graphic corresponding to the circle 32 is superimposed on the Hartmann image on the monitor 85 and displayed.

  Then, the outer circumference, area, and position information of the circle 32 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 compensable region is limited to a light beam in a certain region (for example, a 4 mm diameter region on the pupil) of 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 compensation is performed based on the aberration detection result by the wavefront sensor 73. That is, in the region where the Hartmann image 31 is formed in the region of the circle 32, the wavefront state can be detected (see FIG. 4B). On the other hand, in the region of the circle 32, in the region S where the Hartmann image 31 is not formed, the wavefront state is not detected. Here, when a part of the wavefront data is missing, information on the entire wavefront cannot be obtained, so that the wavefront aberration in the wavefront correction region is not properly measured (see FIG. 4A). Therefore, as shown in FIG. 5A, even when aberration compensation is performed, the aberration is not properly removed as shown in the aberration compensation graphic 41.

<Description of operation>
The operation of the fundus imaging apparatus having the above configuration will be described. First, the examiner adjusts the position of the photographing unit 500 by operating a joystick (not shown) while roughly observing the anterior eye part image (not shown) displayed on the screen of the monitor 85 to perform rough alignment. Further, the examiner instructs the subject to fixate a fixation target (not shown). When alignment 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 performs wavefront detection necessary for aberration compensation.

  Next, the control unit 80 calculates the compensation area (for example, the circle 32) of the wavefront compensation device 72 set on the wavefront sensor 73 and the detection area of the fundus reflection light beam (for example, the Hartmann image 31) by the wavefront sensor 73. Deviation information is detected (acquired). Then, the control unit 80 drives the drive mechanism 505 based on the detection result, adjusts the position of the imaging unit 500, and moves the imaging unit 500 so that the deviation information is within an allowable range.

  For example, first, the control unit 80 sequentially detects the position of the point image received at the outermost side among the Hartmann images 31 received by the wavefront sensor 73, and detects the position information of the Hartmann image outer periphery 31b. Thereby, the detection area of the Hartmann image 31 is obtained.

  Next, the control unit 80 compares the position information of the Hartmann image outer periphery 31b and the position information of the circle 32 (aberration compensationable region), and the wavefront measurement region satisfies the aberration compensationable region beyond the allowable range based on the comparison result. Judge whether it is.

  More specifically, the control unit 80 compares the region surrounded by the Hartmann image outer periphery 31b (see the dotted line) with the region surrounded by the circle 32. Here, the control unit 80 determines that it is sufficient (OK) when the region formed by the circle 32 is within the region formed by the Hartmann image outer periphery 31b (see FIG. 4B). Moreover, the control part 80 determines with it being inadequate (NG), when the area | region which the circle | round | yen 32 comprises is not settled in the area | region which the outer periphery 31b comprises (refer Fig.4 (a)). If it is determined that the information is insufficient (NG), the photographing unit 500 is moved so that the deviation information is within the allowable range, and the region formed by the circle 32 is positioned within the region formed by the Hartmann image outer periphery 31b. Adjust. Thereby, as shown in FIG. 5B, when the aberration compensation is executed, the aberration is appropriately removed as shown in the aberration graphic 41.

  In the above determination, the index pattern image may not satisfy 100% of the compensable region, and the wavefront aberration may be measured with a certain accuracy (for example, 95% region). If a deviation is detected in the determination result, the control unit 80 drives the drive mechanism 505 to receive the index pattern image exceeding a certain allowable range (for example, a certain ratio or more) within the compensation range. The imaging unit 500 is moved so that the

<Start wavefront detection / Start fundus photography / Feedback control>
After the position of the imaging unit 500 is adjusted, the control unit 80 determines whether the region formed by the circle 32 is within the region formed by the Hartmann image outer periphery 31b. The control unit 80 detects the wavefront aberration of the eye E based on the detection result of the wavefront sensor 73 and the fundus imaging optical system when the region formed by the circle 32 is within the region formed by the Hartmann image outer periphery 31b. 100 starts fundus imaging.

  The controller 80 calculates an aberration compensation amount based on the aberration detection result, and controls the wavefront compensation device 72 using the calculation result to compensate for 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 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.

<Position shift after alignment>
Here, even after the alignment is adjusted, for example, the fixation state of the eye E is not sufficiently maintained, so that a positional deviation occurs between the eye E and the apparatus, and the deviation information is within an allowable range. It may come off. Therefore, when the deviation information is out of the allowable range, the control unit 80 relatively adjusts the positional relationship between the wavefront aberration detection optical system 110 and the eye E so that the deviation information is within the allowable range. .

<Pause feedback control>
Hereinafter, a control operation in the case where a positional deviation has occurred will be described with reference to the flowchart of FIG. When the deviation information is out of the allowable range after the wavefront compensation operation is started as described above (for example, when it is detected that the circle 32 is out of the outer periphery 31a), the control unit 80 performs the feedback. Stop control temporarily. Then, the control unit 80 holds the aberration compensation amount by the wavefront compensation device 72 with the aberration correction amount before the deviation information is out of the allowable range (for example, before the circle 32 is removed). In addition, the control unit 80 performs readjustment of alignment so that the deviation information is within an allowable range (for example, the circle 32 is within the outer periphery 31a).

  For example, the control unit 80 does not transmit the drive signal based on the aberration detection result after the circle 32 is detached to the wavefront compensation device 72, and the circle 32 is within the outer periphery 31a (immediately before or before it is detached). Are continuously output to the wavefront compensation device 72. Then, the control unit 80 operates the wavefront compensation device 72 with the same drive signal until the circle 32 is within the outer periphery 31a. The wavefront compensation device 72 only needs to be operated with a compensation amount that reflects the aberration detection result before the circle 32 is removed, and a drive signal similar to that before the circle 32 is removed may be applied.

  In the case of LCOS, the control unit 80 may hold the voltage application amount to each pixel of the LCOS as it is before the circle 32 is detached from the outer periphery 31a, and make the LCOS refractive index constant. In the case of a deformable mirror, the control unit 80 similarly holds the voltage application amount to each drive unit as it is before the circle 32 is detached from the outer periphery 31a, and makes the shape of the entire mirror constant. .

  Even after the circle 32 is removed, the control unit 80 operates the fundus imaging optical system 100 to continuously acquire a high-magnification image of the fundus, and the monitor 85 uses the acquired high-magnification image as a moving image. Is output at any time.

<Readjustment of alignment>
In addition, the control unit 80 controls the drive mechanism 505 to move the photographing unit 500 so that the circle 32 is within the outer periphery 31a. Depending on the fixation state of the eye E, the alignment may naturally return to an appropriate state.

<Resumption of feedback control>
When the alignment is readjusted in this way and it is detected that the circle 32 has returned to the outer periphery 31a, the control unit 80 outputs a return signal for resuming the feedback control. Here, the control unit 80 detects the wavefront aberration by the wavefront sensor 73, and sends a drive signal based on the aberration detection result after the alignment return 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.

  As described above, when a positional deviation occurs after the feedback control is started, the feedback control is temporarily stopped, so that wavefront compensation based on the aberration detection result when the positional deviation occurs is not performed. Therefore, it is avoided that the wavefront compensation device 72 (for example, refractive index if LCOS, mirror shape if deformable mirror) is operated with an incorrect aberration compensation amount due to the aberration detection result when fixation disparity occurs. Is done. Then, after the positional deviation is adjusted, the time until returning to the appropriate wavefront compensation is shortened.

  Further, after the alignment is restored, since the aberration compensation feedback control is resumed from the aberration compensation amount of the wavefront compensation device 72 in the previous alignment completion state, the drive of the wavefront compensation device 72 can be reduced and a smooth fundus image can be obtained smoothly. Is obtained. Further, even when a positional deviation occurs, the control state of the wavefront compensation device 72 is maintained as it was before the positional deviation occurred, so that if the alignment deviation is small, the circle 32 is out of the outer periphery 31a. Even so, good high-magnification fundus images with little blur are continuously acquired.

  In addition, when the misalignment occurs again after restarting the feedback control, the control unit 80 may similarly perform the stop and return operations of the feedback control.

  In this embodiment, the control unit 80 maintains the control state of the wavefront compensation device 72 with the aberration compensation amount before the circle 32 is removed from the outer periphery 31a. However, the present invention is not limited to this, and the wavefront aberration is not limited to this. Ford back control may be resumed based on the detection result in a properly detected state.

  For example, the control unit 80 causes the storage unit 81 to store the wavefront control information when the deviation information is within the allowable range, and when the deviation information returns to the allowable range, the wavefront control information of the wavefront compensation device 72 is stored. This is reflected in the wavefront compensation device 72.

  Specifically, in a state where the circle 32 is within the outer periphery 31b, the examiner or the control unit 80 outputs a predetermined trigger signal and stores the aberration compensation amount data of the wavefront compensation device 72 in the storage unit 81. Keep it. For example, the aberration compensation amount of the wavefront compensation device 72 after a lapse of several seconds after the circle 32 fits on the outer periphery 31 b is stored in the storage unit 81. Further, the aberration compensation amount may be always stored in the storage unit 81, and the aberration compensation amount may be arbitrarily selected from the stored data.

  Thereafter, when the circle 32 is removed from the outer periphery 31a, the control unit 80 temporarily stops the feedback control, and moves the photographing unit 500 so that the circle 32 is again accommodated in the Hartmann image 31. Then, when the alignment is readjusted and the return signal is output, the control unit 80 calls the data of the aberration compensation amount of the wavefront compensation device 72 stored in advance in the storage unit 81, and uses it to use the wavefront compensation. The device 72 is controlled.

  In the above description, any configuration in which the positional relationship between the detection optical system 110 and the eye E is relatively adjusted may be used. For example, the chin rest may be moved with respect to the eye E so that the deviation information is within an allowable range. In addition, a light deflection unit that changes the traveling direction of the measurement light beam may be provided in the optical path of the detection optical system 110, and the positional relationship may be adjusted by driving the light deflection unit.

  In the present embodiment, the shift information between the area that can be compensated for by the wavefront compensation device 72 and the detection area of the fundus reflected light beam by the wavefront sensor 73 is detected based on the output signal of the wavefront sensor, but the present invention is not limited to this. For example, an anterior ocular segment observation system is provided, and the alignment detection result detected by the anterior ocular segment observation system is associated with the above-described deviation information in advance. Then, based on the alignment detection result, it may be determined whether the deviation information is within an allowable range. Further, a compensable region is set on the anterior ocular segment observation camera, a pupil part is extracted from the anterior segment image by image processing, and the position information of the compensable region and the positional information on the outer periphery of the pupil are compared to each other. A shift between regions may be detected.

  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 interference optical system (OCT optical system) that captures a tomographic image of the eye to be inspected by receiving the light beam reflected from the fundus of the eye to be examined and the interference light by the reference light.

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 specific example of the parameter | index pattern image on a wavefront sensor, and a compensation possible area | region. It is the figure which showed the aberration compensation screen displayed on the screen of a monitor. It is a flowchart which shows the control operation | movement when a position shift arises.

DESCRIPTION OF SYMBOLS 1 Light source 10 Diopter correction part 15 Scan part 20 Face support unit 21 Base 40 Aberration compensation screen 54 Light receiving element 72 Wavefront compensation device 73 Wavefront sensor 76 Light source 80 Control part 81 Storage part 85 Monitor 100 Fundus imaging optical system 110 Wavefront aberration detection Optical system 200 Second imaging unit 300 Tracking unit 400, 410 Deflection unit 500 Imaging unit 505 Drive mechanism

Claims (5)

A fundus imaging optical system that receives 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 detection optical system that projects measurement light toward the fundus of the subject's eye and detects reflected light from the fundus by a wavefront sensor;
Detecting means for detecting deviation information between a compensable region of the wavefront compensation device set on the wavefront sensor and a detection region of a fundus reflected light beam by the wavefront sensor;
Control means for performing feedback control that repeats detection of wavefront aberration of the subject's eye based on a detection signal from the wavefront sensor and control of the wavefront compensation device based on the detection result, the detection means being detected by the detection means When the deviation information falls outside the allowable range, the feedback control is temporarily stopped, and when the deviation information returns to the allowable range, the feedback control is resumed. . The fundus imaging apparatus according to claim 1,
A fundus photographing apparatus with wavefront compensation comprising display means for outputting a fundus image continuously captured by a fundus imaging optical system as a moving image. The fundus photographing apparatus according to claim 2,
Further, the fundus photographing apparatus with wavefront compensation includes a position adjusting unit that relatively adjusts a positional relationship between the detection optical system and the eye to be examined so that the deviation information is within an allowable range. The fundus imaging apparatus according to claim 3,
When the feedback control is stopped, the control means holds the aberration compensation amount by the wavefront aberration compensation device at the aberration compensation amount before the deviation information is out of the allowable range. The fundus imaging apparatus according to claim 3,
Storage means for storing wavefront control information of the wavefront compensation device,
The control means stores the wavefront control information when the deviation information is within an allowable range in the storage means, and when the deviation information is restored within the allowable range, the wavefront control information of the wavefront compensation device is stored. A fundus photographing apparatus with wavefront compensation, which is reflected in the wavefront compensation device.

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