JP6572560B2 - Fundus imaging device with wavefront compensation - Google Patents

Description

  The present disclosure relates to a fundus imaging apparatus with wavefront compensation that captures a fundus image of a subject's eye in a state in which the wavefront aberration of the subject's eye is corrected.

  An apparatus is known that detects wavefront aberration of an eye using a wavefront sensor such as a Shack-Hartmann sensor, controls a wavefront compensation device based on the detection result, and takes a fundus image after wavefront compensation at a cellular level ( Patent Document 1).

JP 2013-52047 A

  The performance of wavefront compensation in a wavefront compensation device has a limit depending on the device design, and a wavefront having a large distortion with respect to the device performance may not be fully compensated. Therefore, in order to obtain a good fundus image, it is important to appropriately compensate for wavefront distortion within the range of device performance.

  Even when wavefront compensation is performed within the range of device performance, the image quality of the fundus image after wavefront compensation tends to deteriorate as the wavefront compensation is performed for a wavefront having a larger distortion. confirmed.

  The present disclosure has been made in view of the above circumstances, and it is an object of the present disclosure to provide a fundus imaging apparatus with wavefront compensation that can capture a fundus image in a state where wavefront compensation is satisfactorily performed.

  The fundus imaging apparatus with wavefront compensation according to the first aspect of the present disclosure is disposed in an optical path of a fundus imaging optical system that receives reflected light from the fundus of a subject's eye and captures a fundus image, and the optical path of the fundus imaging optical system. A wavefront compensation device for controlling wavefront aberration of an eye to be compensated by controlling a wavefront of incident light, and an aberration detection optical system for detecting the wavefront aberration, and projecting measurement light onto the eye to be examined In addition, the relative position of the aberration detection optical system that detects the reflected light of the measurement light from the fundus of the subject's eye with the detector, the eye to be examined, and the effective region in which the wavefront compensation is effective in the wavefront compensation device An adjustment means for adjusting the relationship, and an aberration amount of the eye to be examined is calculated based on a detection signal from the detector; and further, the alignment of the eye to be examined and the effective area by the adjustment means is guided by the calculation Based on the amount of aberration obtained Arithmetic control means to be executed.

  According to the fundus imaging apparatus with wavefront compensation of the present disclosure, it is possible to capture a fundus image in a state where the wavefront compensation is performed favorably.

It is the figure which showed the external view of the imaging device of this embodiment. It is the schematic diagram which showed the optical system of the imaging device. It is the block diagram which showed the control system of the imaging device of this embodiment. It is the figure which showed the compensation possible area | region and effective area | region on a wavefront compensation device. It is a figure explaining the example of an index pattern image and an effective field. It is the figure which showed the aberration correction screen displayed on the screen of a monitor. It is the flowchart which showed the flow of operation | movement in an imaging device. It is a figure which shows the aberration correction graphic in the stage which finished the 1st alignment. It is the flowchart which showed operation | movement of the imaging device in 2nd alignment. It is a figure which shows the aberration correction graphic in the stage which finished 2nd alignment.

  Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. The imaging apparatus 1 is a fundus imaging apparatus with wavefront aberration compensation that captures a fundus image of the eye E with the wavefront aberration of the eye E corrected.

  First, a schematic configuration of the photographing apparatus 1 will be described with reference to FIG. The photographing apparatus 1 includes a base 510, a face support unit 600, and a photographing 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 movable 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 support unit 600. In the present embodiment, the chin rest 610 moves in each of the X, Y, and Z directions when the electric movement mechanism 610a is driven. The electric movement mechanism 610a may be configured by combining a plurality of electric actuators that move the chin rest 610 in one direction.

  Next, the optical system of the photographing apparatus 1 will be described with reference to FIG. The imaging apparatus 1 of the present embodiment includes 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 20, 30, and 72, and a second imaging unit. 200 and an anterior ocular segment observation unit 700.

  The fundus imaging optical system 100 projects laser light (illumination light) on the eye E and receives reflected light from the fundus of the laser light to capture a fundus image of the eye E. The fundus of the eye E is photographed by the fundus imaging optical system 100 with high resolution (high resolution) and high magnification. As described below, the fundus imaging optical system 100 may have a configuration of a scanning laser ophthalmoscope using a confocal optical system, for example. The fundus imaging optical system 100 includes a first illumination optical system 100a and a first imaging optical system 100b. In this embodiment, the aberration compensation units 20, 30, and 72 are disposed in the fundus imaging optical system 100 in order to correct the aberration of the eye E. The aberration compensation unit is roughly classified into a wavefront compensation device 72 and a second correction unit. In the present embodiment, the second correction unit includes an optical system for correcting low-order aberrations of the second order or lower. In the present embodiment, the second correction unit includes a diopter correction unit 20 and an astigmatism correction unit 30. The diopter correction unit 20 includes an optical system for correcting diopter (that is, defocus component). The astigmatism correction unit 30 includes an optical system for correcting astigmatism components.

  The first illumination optical system 100a illuminates the fundus two-dimensionally by irradiating the eye E with laser light and scanning the laser light on the fundus. The first illumination optical system 100a includes a light source 11, a lens 12, a polarization beam splitter (PBS) 14, a beam splitter (BS) 71, a concave mirror 16, in an optical path from the light source 11 (first light source) to the fundus. Concave mirror 17, flat mirror 18, aberration compensation unit 72 (wavefront compensation device 72), beam splitter (BS) 75, concave mirror 21, concave mirror 22, scanning unit 25, concave mirror 26, concave mirror 27, flat mirror 28, Aberration compensation unit 30 (astigmatism correction unit 30), lens 32, plane mirror 33, aberration compensation unit 20 (diopter correction unit 20), plane mirror 35, concave mirror 36, deflection unit 400, dichroic mirror 90, concave mirror 41, It has a plane mirror 42, a plane mirror 43, and a concave mirror 45.

  The light source 11 emits laser light. In the present embodiment, the laser light has a near-infrared wavelength that is difficult to be visually recognized by the eye E. For example, in the present embodiment, the light source 11 is an SLD (Super Luminescent Diode) having a wavelength of 840 nm. The light source 11 may be any light source that emits spot light having a high convergence property, and may be, for example, a semiconductor laser.

  The laser light emitted from the light source 11 is converted into parallel light by the lens 12 and then enters the wavefront compensation device 72 via the PBS 14, BS 71, concave mirrors 16 and 17, and the flat mirror 18. In the present embodiment, the laser light passes through the PBS 14 and becomes a light beam having only an S-polarized component. The wavefront compensation device 72 corrects higher-order aberrations of the eye E by controlling the wavefront of the incident light. The detailed configuration of the wavefront compensation device 72 will be described later. In the present embodiment, the laser beam is guided from the wavefront compensation device 72 to the BS 75, reflected by the concave mirror 21 and the concave mirror 22, and travels toward the scanning unit 25.

  In the present embodiment, the scanning unit 25 is used together with the deflecting unit 400 in order to scan laser light two-dimensionally on the fundus. The scanning unit 25 is a resonant mirror used for main scanning of laser light. The laser light is scanned in the X direction on the fundus by the scanning unit 25.

  The light that has passed through the scanning unit 25 enters the astigmatism correction unit 30 through the concave mirrors 26 and 27 and the plane mirror 28.

  The astigmatism correction unit 30 is a unit for correcting an astigmatism component (secondary) in the aberration of the eye E to be examined. Various configurations are possible for the astigmatism correction unit 30. For example, the structure provided with a cross cylinder lens may be sufficient. In this case, the astigmatism correction unit 30 may include a pair of cylinder lenses having the same cylindrical power and arranged in opposite directions on the optical axis. Further, a mechanism for independently rotating each cylinder lens may be included. As another configuration, the astigmatism correction unit 30 includes a plurality of lenses having different cylindrical powers, a mechanism for inserting and removing each lens independently from the optical axis, and an axis angle of each lens on the optical axis. You may provide the mechanism to change.

  In the present embodiment, the astigmatism correction unit 30 controls the arrangement of the lenses in the astigmatism correction unit 30 according to the value indicating the astigmatism component measured for the eye E. As a result, the astigmatism component is corrected.

  The laser light that has passed through the astigmatism correction unit 30 is then incident on the diopter correction unit 20 via the lens 32 and the plane mirror 33.

  The diopter correction unit 20 is a unit for performing diopter correction. The diopter correction unit 20 includes a pair of lenses and plane mirrors in addition to the drive unit 20a. The optical path length is adjusted by moving the plane mirror and lens of the diopter correction unit 20 in a predetermined direction by the drive unit 20a. As a result, the diopter (that is, the defocus component of the aberration of the eye E) is corrected.

  The illumination light guided from the diopter correction unit 20 to the plane mirror 35 is reflected by the concave mirror 36 and travels toward the deflection unit 400.

  The deflecting unit 400 scans the laser light emitted from the light source 11 in the vertical direction (Y direction) on the fundus. Furthermore, the deflecting unit 400 is also used to move the scanning range of the laser light on the fundus. For example, in the present embodiment, the deflecting unit 400 may include two optical scanners (specifically, an X galvanometer mirror and a Y galvanometer mirror) having different directions of deflecting laser light.

  The light that has passed through the deflecting unit 400 is guided into the pupil of the eye E through the dichroic mirror 90, the concave mirror 41, the plane mirrors 42 and 43, and the concave mirror 45. The laser light is collected on the fundus of the eye E. As described above, the laser beam is two-dimensionally scanned on the fundus by the operations of the scanning unit 25 and the deflecting unit 400.

  Further, the dichroic mirror 90 has a characteristic of transmitting a light beam from the second photographing unit 200 described later and reflecting a light beam from the light source 11 and a light source 76 described later. Note that the emission ends of the light sources 11 and 76 and the fundus of the eye E are conjugate. In this way, the first illumination optical system 100a is formed.

  Next, the first photographing optical system 100b will be described. The first imaging optical system 100 b receives the reflected light of the laser light irradiated on the fundus by the light receiving element 56. The imaging device 1 acquires a first fundus image (cell image, AO-SLO image) based on a signal from the light receiving element 56. The first imaging optical system 100b shares the optical path from the eye E to the BS 71 with the first illumination optical system 100a. The first imaging optical system 100 includes elements arranged in the reflection side optical path of the BS 71, that is, 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). Further, the pinhole plate 54 is placed at a position conjugate with the fundus.

  The fundus reflection light of the laser light from the light source 11 traces the first illumination optical system 100 a in the reverse direction, is reflected by the BS 71 and the flat 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. A part of the illumination light is reflected on the cornea, but most of the illumination light is removed by the pinhole plate 54. Therefore, the light receiving element 56 can receive the reflected light from the fundus while suppressing the influence of corneal reflection.

  A first fundus image (that is, also referred to as a cell image or an AO-SLO image) is acquired by an image processing unit (for example, the control unit 800) processing a light reception signal of the light receiving element 56. In this embodiment, a fundus image of one frame is formed by main scanning of the scanning unit 25 and sub-scanning of a Y-scan galvanometer mirror provided in the deflection unit 400. Note that the deflection angle (swing angle) of the mirror in the scanning unit 25 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 E, the imaging range of the first fundus image is about 500 μm square.

  Further, when the reflection angle of the X-scanning galvanometer mirror and the Y-scanning galvanometer mirror provided in the deflection unit 400 is moved larger than the imaging field angle of the first fundus image, the first fundus image is captured on the fundus. The position (that is, the scanning range of the laser beam) is changed.

  The second photographing unit 200 is a unit for obtaining a fundus image (second fundus image) having a wider angle of view than the angle of view of the first photographing unit 100. The second fundus image is used, for example, as an image for position designation and position confirmation for obtaining the first fundus image. The second imaging unit 200 of the present embodiment preferably has a configuration capable of acquiring and observing a 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). For example, as the second imaging unit 200, an observation / imaging optical system of an existing fundus camera and an optical system and a control system of a scanning laser ophthalmoscope (SLO) may be used.

  The anterior segment observation unit 700 is a unit that illuminates the anterior segment of the eye E with visible light and captures a front image of the anterior segment. An image captured by the anterior segment observation unit 700 is output to the monitor 850. The anterior ocular segment image acquired by the anterior ocular segment observation unit 700 is used for alignment between the imaging unit 500 and the eye E to be examined. The dichroic mirror 95 has a characteristic of transmitting the light beam from the second photographing unit 200 and reflecting the light beam from the anterior ocular segment observation unit 700.

  Next, the aberration detection optical system 110 will be described. The aberration detection optical system 110 includes a wavefront sensor 73. The aberration detection optical system 110 projects measurement light onto the fundus of the eye E, and receives (detects) the fundus reflection light of the measurement light as an index pattern image with the wavefront sensor 73. The aberration detection optical system 110 has a part of optical elements on the optical path of the first illumination optical system 100a and the first photographing optical system 100b (in the present embodiment, on the common optical path), and the optical paths of the optical systems 100a and 100b. Some are shared. That is, the aberration detection optical system 110 of the present embodiment shares the BS 71 to the concave mirror 45 arranged on the optical path of the optical systems 100a and 100b with the optical systems 100a and 100b. Further, the aberration detection optical system 110 includes a light source 76, a lens 77, PBS 78, BS 75, BS 71, a dichroic mirror 86, a PBS 85, a lens 84, a plane mirror 83, and a lens 82.

  The light source 76 is used for wavefront aberration detection of the eye E. In the present embodiment, the light source 76 emits light having a wavelength different from that of the light source 11. As an example, in this embodiment, a laser diode that emits laser light having a wavelength of 780 nm is used as the light source 76 as measurement light. The measurement light emitted from the light source 76 is converted into a parallel light beam by the lens 77 and then incident on the PBS 78.

  The PBS 78 is an example of first polarization means provided in the wavefront compensation unit. The PBS 78 polarizes the light emitted from the light source 76 in a predetermined direction. More specifically, the PBS 78 is polarized in a direction (ie, P-polarized light) orthogonal to the polarization direction (ie, S-polarized light) of the PBS 14. The light that has passed through the PBS 78 is reflected by the BS 75 and guided to the optical path of the first illumination optical system 100a. As a result, the measurement light is condensed on the fundus of the eye E through the optical path of the first illumination optical system 100a.

  The measurement light is reflected at the condensing position of the fundus (for example, the retina surface). The fundus reflection light of the measurement light follows the optical path of the first illumination optical system 100a (that is, the optical path of the first photographing optical system 100b) in the opposite direction to that during projection. On the way, the measurement light is reflected by the wavefront compensation device 72. Thereafter, the measurement light is reflected by the BS 71, thereby deviating from the optical path of the first illumination optical system 100a. Thereafter, the measurement light is reflected by the dichroic mirror 86 and guided to the wavefront sensor 73 through the PBS 85, the lens 84, the plane mirror 83, and the lens 82.

  The PBS 85 is a second polarization unit provided in the wavefront compensation unit. The PBS 85 is used to guide light to the wavefront sensor 73 by transmitting light polarized in one direction (here, S-polarized light) out of the light irradiated to the eye E from the light source 76. The The PBS 85 blocks a component polarized in a direction orthogonal to the transmitted component (P-polarized light). The dichroic mirror 86 has a characteristic of transmitting light (840 nm) having the wavelength of the light source 11 and reflecting light (780 nm) having the wavelength of the light source 76 for detecting aberration. Therefore, the wavefront sensor 73 detects light having an S-polarized component from the fundus reflection light of the measurement light. In this way, light reflected by the cornea and the optical element is suppressed from being detected by the wavefront sensor 73.

  The wavefront sensor 73 receives fundus reflection light of measurement light for aberration measurement in order to detect wavefront aberration of the eye E. As the wavefront sensor 73, an element that can detect wavefront aberration including low-order aberration and high-order aberration (more specifically, a Hartmann Shack detector, a wavefront curvature sensor that detects a change in light intensity, and the like) is used. May be. In the present embodiment, the wavefront sensor 73 includes, for example, a microlens array composed of a large number of microlenses, a two-dimensional imaging element 73a (or a two-dimensional light receiving element) for receiving a light beam transmitted through the microlens array, Have The microlens array of the wavefront sensor 73 is disposed at a position substantially conjugate with the pupil of the eye E to be examined. Further, the imaging surface (light receiving surface) of the two-dimensional imaging element 73a is disposed at a position substantially conjugate with the fundus of the eye E to be examined.

  An index pattern image 61 (Hartmann image in this embodiment) is formed on the imaging surface of the two-dimensional imaging element 73a by the light beam that has passed through the microlens array (not shown). Therefore, the fundus reflection light passes through the microlens array and is received by the two-dimensional imaging device 73a, thereby being imaged as a Hartmann image (dot pattern image). In the present embodiment, the aberration information of the eye E is acquired from the Hartmann image, and the wavefront compensation device 72 is controlled based on the aberration information. Details of the Hartmann image will be described later.

  The wavefront compensation device 72 is disposed in the optical path of the fundus imaging optical system 100 (in the present embodiment, in the common optical path of the fundus imaging optical system 100 and the aberration detection optical system 110). The wavefront compensation device 72 compensates the wavefront aberration of the eye E by controlling the wavefront of the incident light. For example, the wavefront compensation device 72 may be configured to compensate the wavefront by modulating the phase of the wavefront. Further, for example, a configuration in which the wavefront is compensated by giving an optical path length difference to each part of the wavefront may be employed. Moreover, the structure which uses both these methods together may be sufficient, and of course, another structure may be sufficient.

  As an example, in the present embodiment, a case where a liquid crystal spatial light modulator is used as the wavefront compensation device 72 will be described. In the following description, it is assumed that a reflective LCOS (Liquid Crystal On Silicon) or the like is used. In this case, the wavefront compensation device 72 reflects the laser light (S-polarized light) from the light source 11, the fundus reflection light (S-polarized light) of the laser light, and the reflected light (S measurement light) of the aberration detection light (S measurement light). It is arranged in a direction in which aberration can be corrected with respect to predetermined linearly polarized light (S-polarized light) such as a polarization component. As a result, the wavefront compensation device 72 can modulate the S-polarized component of the incident light. Further, in the present embodiment, the reflection surface of the wavefront compensation device 72 is disposed at a position that is substantially conjugate with the pupil of the eye E to be examined.

  In the wavefront compensation device 72 of the present embodiment, the alignment direction of the liquid crystal molecules in the liquid crystal layer is substantially parallel to the polarization plane of incident reflected light. Further, the predetermined plane of the liquid crystal molecules that rotates in accordance with the change in the voltage applied to the liquid crystal layer includes the incident optical axis and the reflected optical axis of the fundus reflection light with respect to the wavefront compensation device 72, and the mirror layer of the wavefront compensation device 72. And a plane that includes the normal line.

  In the above description, the light source 71 that emits light having a wavelength different from that of the light source 11 (first light source) for fundus photographing is used as the aberration detection light source. However, the light source 11 for fundus photography may also be used as a light source for detecting aberrations (that is, emitting measurement light).

  In the present embodiment described above, the wavefront sensor (more specifically, its microlens array) and the wavefront compensation device are used as the pupil conjugate of the eye E. It may be a conjugate position, and may be, for example, a corneal conjugate.

  Next, with reference to FIG. 3, a control system of the photographing apparatus 1 in the present embodiment will be described. The photographing apparatus 1 includes an arithmetic control unit 800 (hereinafter abbreviated as the control unit 800). The control unit 800 is a processor (for example, a CPU) that controls the entire apparatus of the photographing apparatus 1. In the present embodiment, a storage unit 801, an operation unit 802, an image processing unit 803, and a monitor 850 are electrically connected to the control unit 800. The control unit 800 includes a light source 11, a scanning unit 15, a diopter correction unit 20, an astigmatism correction unit 30, a light receiving element 56, a wavefront compensation device 72, a wavefront sensor 73, a light source 76, a second imaging unit 200, and a deflection unit. 400, the electric moving mechanism 610a, and the anterior ocular segment observation unit 700 are electrically connected.

  The storage unit 801 stores various control programs and fixed data. Further, the storage unit 801 may store an image captured by the imaging device 1, temporary data, and the like.

  The control unit 800 controls each member described above such as the first imaging unit 100 based on the operation signal output from the operation unit 802. The operation unit 802 is connected to a mouse or the like (not shown) as an operation member operated by the examiner.

  The image processing unit 803 forms, on the monitor 850, 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 56 and the second imaging unit 200. Note that the image processing unit 803 may be configured to be shared by the control unit 800.

  The monitor 850 may be a display monitor mounted on the photographing apparatus 1 or a general-purpose display monitor that is separate from the photographing apparatus 1. Moreover, the structure in which these were used together may be sufficient. The monitor 850 can display fundus images (first fundus image and second fundus image) captured by the imaging apparatus 1 as moving images and still images.

  The control of the wavefront compensation device 72 by the controller 800 is executed based on the wavefront aberration detected by the wavefront sensor 73. In the present embodiment, feedback control of the wavefront compensation device 72 based on the detection signal from the wavefront sensor 73 is performed. By controlling the wavefront compensation device 72, the high-order aberrations of the laser light emitted from the light source 11 and the fundus reflection light of the laser light are removed together with the S-polarized component of the reflected light of the light source 76. In this way, the aberrations of the laser light emitted from the light source 11 and the fundus reflection light of the laser light are removed. As a result, the imaging apparatus 1 acquires a high-resolution first fundus image from which higher-order aberrations of the eye E have been removed (wavefront compensated). In the present embodiment, low-order aberrations are corrected by the diopter correction unit 20 and the astigmatism correction unit 30, respectively.

  Here, an overview of wavefront compensation control using the wavefront compensation device 72 and the wavefront sensor 73 will be described with reference to FIGS. As shown in FIG. 4, the wavefront compensation device 72 can control the wavefront of incident light in a range where the compensable region 40 is formed. In FIG. 4, a region 41 on the compensable region 40 indicates an effective region on the wavefront compensation device 72. The effective area 41 is an area where aberration correction is effectively performed based on the detection signal from the wavefront sensor 73. The range (that is, the position and the size) in which the effective region 41 is set in the compensable region 40 may be determined in advance as, for example, a certain region (whole or part) in the compensable region 40. . However, the present invention is not necessarily limited to this, and the range in which the effective area 41 is set may be displaced on the compensable area 40. In this case, the configuration may be such that the control unit 800 described later controls the range of the effective region 40 in the compensable region 40. In the present embodiment, the compensable region 40 has a size of 16 × 12 mm. As an example, the effective area 41 shown in FIG. 4 has a size of φ8.64 mm. Since the compensable region 40 has a sufficient size compared to the effective region 41, the effective region 41 can be changed within the compensable region 40 in at least one of position, size, and shape (details will be described later). To do). In the wavefront compensation device 72, the effective region 41 may be limited to a light beam in a certain region (for example, a 6 mm diameter region on the pupil) of the entire incident light. In this case, the wavefront compensation device 72 of the present embodiment also reflects the light incident on the outside of the effective region 41 toward the light receiving element 56 similarly to the light incident on the effective region 41, but enters the outside. The wavefront of the emitted light cannot be compensated.

  On the other hand, as shown in FIG. 5, as described above, the Hartmann image 61 is captured by the two-dimensional image sensor 73 a of the wavefront sensor 73. The Hartmann image 61 shows a group of a plurality of point images 61 a received on the wavefront sensor 73. A light beam that has passed through one lens array forms one point image 61. In the area where the point image 61a is detected by the wavefront sensor 73, aberration detection is possible.

  In FIG. 5, the effective area 41 (that is, the circle 62 corresponds to the outer periphery of the effective area 41) is virtually indicated by a circle 62. In the present embodiment, the wavefront aberration used for controlling the wavefront compensation device 72 is detected from the Hartmann image 61 included in the circle 62. The positional relationship between the circle 62 (effective region 41) and the Hartmann image 61 can be adjusted by, for example, displacing the position of the effective region 41 on the wavefront compensation device 72. Further, the positional relationship between the circle 62 and the Hartmann image 61 is also displaced according to the positional relationship between the imaging optical axis and the pupil position of the eye E to be examined. In the present embodiment, the Hartmann image 61 and the circle 62 are displayed on the monitor 850 as a part of the aberration correction screen 60.

  As described above, in the present embodiment, the region where the Hartmann image 61 is formed is a region on which a wavefront aberration is measured by the aberration detection optical system 110 on a certain surface (for example, on the anterior ocular segment conjugate surface) (that is, "Wavefront measurement region"). A region where wavefront compensation is effectively performed by the wavefront compensation device 72 is an effective region projected on the certain surface (an effective region in the wavefront measurement region).

  Here, the aberration correction screen 60 will be described with reference to FIG. The aberration correction screen 60 is generated based on signals from the light receiving element 56, the wavefront sensor 73, and the like. The aberration correction screen 60 includes a Hartmann image display screen 64, an aberration correction graphic display screen 65, and a cell display screen 66.

  On the Hartmann image display screen 64, the Hartmann image 61 and the circle 62 are shown superimposed on the same plane (for example, on the light receiving surface of the wavefront sensor 73). The position and size of the circle 62 are set by the control unit 800. For example, the control unit 800 sets a circle 62 in an area corresponding to the position and size of the effective area 41 on the wavefront compensation device 72. Information defining the outer circumference, region, etc. of the circle 62 on the Hartmann image display screen 64 can be obtained in advance from the result of calibration or simulation, for example.

  In FIG. 6, the mark 62 a located at the center of the circle 62 is a graphic showing the center position of the effective area 41 on the wavefront sensor 73. On the aberration correction graphic display screen 65, an aberration correction graphic 65a indicating the correction degree (residual aberration) of the aberration correction is displayed.

  The aberration correction graphic 65a represents the distribution of wavefront aberration of the light beam incident on the wavefront sensor 73 by contour lines. The aberration correction graphic 65 a is generated, for example, when the control unit 800 processes the Hartmann image 61 captured through the wavefront sensor 73. As a specific example, an RMS value (average square root) of wavefront aberration may be obtained for each position as a processing result of the Hartmann image 61, and may be generated based on the RMS value at each position. In this case, it may be evaluated that the wavefront aberration is larger as the contour lines in the aberration correction graphic 65a are denser.

  The cell display screen 66 displays a cell image 66a of the fundus that is actually captured (that is, a first fundus image, an AO-SLO image).

  Here, the aberration correction is performed based on the detection result of the wavefront aberration by the wavefront sensor 73. That is, in the region where the Hartmann image 61 is formed inside the circle 62, the wavefront state can be detected (see FIG. 5B). On the other hand, in the region S where the Hartmann image 61 is not formed inside the circle 62, the state of the wave front is not detected. Here, when part of the wavefront data is missing (see, for example, FIG. 6A), the wavefront aberration in the effective region 41 is not properly measured because information on the entire wavefront cannot be obtained. Therefore, even if the aberration correction is executed, the aberration is not properly removed as shown in the aberration correction graphic 65 of FIG. In this case, the cell image 66a is not displayed well. In addition, it is difficult to take a good image of the cell image 66a.

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

  When the photographing apparatus 1 is turned on, the control unit 800 executes main processing according to the control program stored in the storage unit 801. The photographing apparatus 1 operates according to the main process.

  In the flowchart shown in FIG. 7, first, the control unit 800 starts acquisition and display of an anterior ocular segment observation image (S1). Thereafter, the control unit 800 may sequentially acquire the anterior ocular segment image based on the imaging signal output from the anterior ocular segment observation unit 700. Further, the control unit 800 may sequentially display the anterior segment image acquired at any time in the display region of the anterior segment image on the monitor 850.

  Next, the positional relationship between the eye E and the imaging unit 500 is adjusted in each of the X, Y, and Z directions (first alignment: S2). The first alignment may be automatically performed by the control unit 800, or may be manually performed based on an examiner's operation on the operation unit 802. Hereinafter, as a specific example, a case where it is performed manually will be described. When alignment is performed, the examiner instructs the subject to fixate a fixation target (not shown).

  In the present embodiment, alignment is performed with reference to the anterior segment image sequentially displayed on the monitor 850. For example, the examiner operates the operation unit 802 while observing the anterior segment image displayed on the monitor 850, thereby driving the electric movement mechanism 610a, and the position of the chin rest 610 in the X, Y, and Z directions. Adjust to. For example, in the XY directions, alignment is performed so that the pupil center of the eye E to be examined is the optical axis center (for example, the image center). The alignment may be performed so that the corneal apex is the center of the optical axis. For example, the alignment may be performed with reference to an alignment index projected onto the cornea by an alignment projection optical system (not shown). For the Z direction, for example, alignment may be performed so that the iris is in focus.

  After the first alignment is completed, in the present embodiment, wavefront compensation control is started by the control unit 800 (S3). That is, the control unit 800 turns on the light source 76 and starts projecting measurement light. The control unit 800 also starts wavefront aberration detection based on an image detected by the wavefront sensor 73 (an example of a detector). The control unit 800 calculates the amount of wavefront aberration based on the detection signal from the wavefront sensor 73. For example, in the present embodiment, calculation based on an image (Hartmann image 61) detected by the wavefront sensor 73 is performed. In this case, for example, the displacement amount of each dot image in the Hartmann image 61 is detected. Then, by applying the Zernike polynomial expansion based on the detected deviation amount, an aberration amount is obtained for each aberration component. As a method for obtaining the aberration amount from the Hartmann image 61, orthogonal expansion other than the above method may be used. In addition, mathematical techniques (that is, operations) other than orthogonal expansion may be used.

  In the case where the Zernike polynomial expansion is applied, it is preferable that at least aberration amounts for the first to fourth order aberrations in the Zernike polynomial are obtained. The second-order aberration in the Zernike polynomial includes defocus and astigmatism, the third-order aberration includes coma and trefoil, and the fourth-order aberration includes spherical aberration and second-order non-linearity. It is known that there are point aberration and tetrafoil. Of course, fifth-order or higher aberrations in the Zernike polynomial may be obtained by calculation. Even when a mathematical technique other than Zernike expansion is applied, it is preferable to obtain at least coma and spherical aberration as a result of the calculation. Furthermore, it is more preferable that defocus and astigmatism are obtained as a result of the calculation.

  In step S3, aberration correction by the wavefront compensation unit (in this embodiment, the second correction units 20 and 30, and the wavefront compensation device 72) is started. In this case, the control unit 800 calculates the aberration amount of the second or lower order low-order aberration (for example, the aberration amount of the defocus component, the aberration amount of the astigmatism component) based on the detection signal from the wavefront sensor 73. Can be done and asked. Then, the control unit 800 drives the second correction units 20 and 30 based on the amount of low-order aberration. As a result, low order aberrations are corrected. Here, as a specific example, drive control of the diopter correction unit 20 according to the amount of aberration of the defocus component and drive control of the astigmatism correction unit 30 according to the amount of aberration of the astigmatism component are performed. . However, only one of the drive controls may be performed.

  Further, the control unit 800 drives and controls the wavefront compensation device 72 based on the aberration amount obtained by the calculation. This compensates for lower and higher order aberrations. In particular, in the present embodiment, as described above, the wavefront compensation device 72 is driven together with the second correction units 20 and 30. Low-order aberrations are corrected by the second correction units 20 and 30 as much as possible, and residual aberrations remaining in the corrected state (that is, higher-order aberrations higher than the third order and lower-order aberrations lower than the second order). Then, the aberration that remains without being corrected by the second correction units 20 and 30) may be corrected using the wavefront compensation device 72. In this case, the control unit 800 performs an operation on the detection signal output from the wavefront sensor 73 in a state where the aberration correction is performed by the second correction units 20 and 30, and based on the calculation result, the wavefront compensation device. 72 is driven and controlled. As a result, the residual aberration is compensated by the wavefront compensation device 72.

  Here, for example, when LCOS is used as the wavefront compensation device 72, the wavefront compensation control includes wavefront aberration detection calculation by the wavefront sensor 73, calculation of the LCOS phase pattern based on the calculation result, and the calculation result. A loop process including a voltage application to each pixel of the LCOS based is performed. In the loop processing, the compensation phase pattern 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 present embodiment, after the wavefront compensation control is started by the process of S3, the wavefront detection, the aberration amount calculation, and the drive control of the wavefront compensation unit based on the calculated aberration amount as described above are sequentially and repeatedly performed. Executed. Note that the control unit 800 stores the aberration amount acquired as a result of the calculation in a memory (for example, the storage unit 801) for each calculation.

  Here, FIG. 8 shows the state of the wavefront of the fundus reflection light at the stage where the first alignment is completed. FIG. 8 is an aberration correction graphic 65 showing the state of the wavefront in the effective area 41 when the wavefront compensation unit is not driven. At the stage where the first alignment is completed, the center position of the effective region 41 in the wavefront compensation device 72 is aligned with the center of the pupil (or the apex of the cornea). In this case, an asymmetric wavefront as shown in FIG. 8 in which the peaks P1 and P2 (that is, the maximum and minimum of the wavefront) are decentered with respect to the center of the effective region 41 may be detected. The asymmetric wavefront distortion cannot be corrected by the second correction units 20 and 30. Such distortion is compensated by driving the wavefront compensation device 72.

  On the other hand, in the imaging device 1 of the present embodiment, the second alignment is guided by the control unit 800 (S4). In the second alignment, the relative positional relationship between the eye E to be examined and the effective region 41 of the wavefront compensation device 72 intersects at least the X and Y directions (that is, the optical axis of the fundus imaging optical system 100). Tweaked (with respect to direction). In the second alignment, the wavefront compensation device 72 (more specifically, in a position where the distortion of the wavefront of incident light (mainly measurement light and fundus reflection light of photographing light) incident on the wavefront compensation device 72 is small. This is done to arrange the effective area 41). In this case, the control unit 800 may guide alignment by automatically adjusting the positional relationship between the eye E and the effective area 41. Further, the alignment may be guided by performing guidance for manually adjusting the positional relationship on the monitor 850 or the like. Below, the case where the control part 800 adjusts the positional relationship of the to-be-tested eye E and the effective area | region 41 automatically as a specific example is demonstrated.

  Here, the operation for guiding the second alignment will be described in detail with reference to the flowchart of FIG. First, the control unit 800 reads out the calculation result of the aberration amount for the coma aberration from the memory. Here, the latest calculation result may be read. Further, it is determined whether or not the read coma aberration amount is equal to or less than a threshold value (S22). In this case, the threshold value may be 0, for example. Of course, the value may be larger than 0. In this case, the threshold value can be set in an allowable range from the viewpoint of the required image quality of the first fundus image, the performance of the wavefront compensation device 72, or both. When it is determined that the amount of coma aberration is equal to or less than the threshold (S22: Yes), the second alignment is terminated and the process proceeds to step S5. On the other hand, when it is determined that the amount of coma aberration is greater than the threshold (S22: No), the process proceeds to step S23.

  In steps S23 to S26, the control unit 800 adjusts the positional relationship between the eye E and the effective area 41 of the wavefront compensation device 72 based on the amount of coma aberration. In the coma aberration, the maximum and minimum peaks appear symmetrically (axially symmetric) with respect to the center of the effective region 41. For this reason, it is considered that the coma aberration has a great influence on the eccentricity of the peaks P1 and P2 in the wavefront as shown in FIG. In the present embodiment, the control unit 800 guides the second alignment so that the coma aberration in the light incident on the effective region 41 is reduced. That is, the control unit 800 adjusts the relative positional relationship between the eye E and the effective area 41 so that the amount of coma aberration obtained from the Hartmann image 61 that fills the effective area 41 becomes smaller.

The relative positional relationship between the eye E and the effective area 41 can be adjusted by the following method, for example.
(1) A method of relatively moving the eye E and the wavefront compensation device 71.
(2) A method of changing the range in which the effective region 41 is set in the compensable region 40 of the wavefront compensation device 71.

  Further, as a specific example of (1), for example, a method of moving at least one of the eye E and the compensation optical system including the wavefront compensation device 71, an optical scanner (in this embodiment, the scanning unit 25 and For example, there is a method of moving the scanning range of the photographing unit 400) in the X and Y directions. The compensation optical system here is an optical system that compensates for the aberration of fundus reflection light. In FIG. 1, the compensation optical system includes members from the wavefront compensation device 72 to the concave mirror 41 in the photographing optical system 100. When the positional relationship between the compensation optical system and the eye E is changed, it is preferable that the positional relationship between the eye E and the aberration detection optical system 110 change in conjunction. That is, when the positional relationship changes, the detection optical axis of the aberration detection optical system and the optical axis of the compensation optical system are preferably maintained coaxially.

  Hereinafter, in the present embodiment, the position of the eye E is moved with respect to the compensation optical system by moving the chin rest 610, and as a result, the relative positional relationship between the eye E and the effective area 41. Will be described as adjusting. In the present embodiment, it is assumed that the apparatus automatically adjusts the positional relationship between the eye E to be examined and the effective region 41 by the control unit 800 driving and controlling the electric movement mechanism 610a.

  In step S23, displacement information about the amount of displacement and the direction of displacement up to the alignment target position is acquired as a result of the calculation. The target position in the present embodiment is the target position of the effective area 41 with the eye E to be examined as a reference. In the present embodiment, the movement direction to the target position and the movement amount to the target position in the second alignment are obtained based on the amount of coma aberration. Then, a vector to the target position is obtained as the displacement information.

  Here, the moving direction to the target position is determined in a direction in which the coma aberration in the incident light to the effective region 41 is suppressed. The direction in which the coma aberration (the amount of aberration) is suppressed is the direction along the line connecting the wavefront peaks P1 and P2 shown in FIG. In this case, the moving direction may be a direction from P1 to P2, or a direction from P2 to P1. This is because a minimum point of the aberration amount (for example, a position where the coma aberration is minimized in the calculation) exists in any direction. Thus, for example, the moving direction can be determined from the Zernike coefficient indicating coma aberration.

  In this case, the control unit 800 preferably sets the direction toward the peak of the wavefront closer to the center of the effective area 41 (that is, the center O of the aberration correction graphic 65a) as the moving direction. For example, in FIG. 8, since “distance m between OP1> distance n between OP2”, the direction from P1 to P2 is set as the movement direction. The closer the peak is, the smaller the amount of movement to a position where the amount of aberration is minimized. Here, as described above, with the displacement of the effective area 41 with respect to the eye E, the positional relationship between the effective area 41 and the Hartmann image 62 changes. When a movement direction in which the movement amount to the minimum point of the aberration amount is smaller is selected, the effective region 41 is easily filled with the Hartmann image 62 even after the movement. As a result, wavefront compensation after movement is easily performed reliably.

  The amount of movement to the target position can be obtained based on, for example, the coma aberration amount and the spherical aberration amount. Here, the spherical aberration is an aberration that appears rotationally symmetric with respect to the center of the effective region 41, and has a relatively large effect of distorting the wavefront. Therefore, in this embodiment, in order to arrange the effective region 41 in a region where the wavefront distortion in incident light is smaller, not only coma aberration but also spherical aberration is taken into consideration (superposition of spherical aberration and coma aberration). In consideration of the combined aberration), a target position in the second alignment is set.

  Here, the exact solution of the movement amount is represented by a cubic equation having a variable between the coma aberration amount and the spherical aberration amount. It may be solved to obtain the amount of movement, but it becomes complicated. Therefore, in the present embodiment, the movement amount is obtained using an approximate expression as follows.

  When coma aberration aberration amount (however, absolute value) is c, spherical aberration aberration amount (however, absolute value) is s, and x = c / (c + s), pupil radius 1 (for example, effective) The movement amount (displacement) normalized with the radius of the region 41 as 1) can be approximated by the following equation (1).

d = 0.454x ³ -0.838x ² -0.0837x (1)
Further, linear approximation may be performed by the following equation (2).

d = 0.44x (2)
As described above, when the coma aberration amount and the spherical aberration aberration amount are obtained, the control unit 800 moves to the target position using either of the equations (1) and (2). The amount can be determined.

  A vector for moving the effective area 41 from the current position to the target position is obtained from the movement direction and the movement amount obtained as described above.

  Next, the control unit 800 simulates the positional relationship between the effective area 41 and the Hartmann image 61 at the target position obtained as described above (S24). For example, by changing the position information of the current effective area 41 by the amount of the above-described vector, the position of the effective area 41 when placed at the target position can be predicted (simulated). Thereby, the position information of the effective area 41 at the target position is obtained. From this positional information and positional information of the Hartmann image 61, the positional relationship between the effective area 41 and the Hartmann image 61 is predicted. Each piece of position information may be, for example, position information at the center of the region or position information of the contour.

  Next, the control unit 800 determines whether or not appropriate wavefront compensation control is possible based on the simulation result when the effective region 41 is set to the target position (S25). That is, when the effective area 41 is arranged at the target position, whether or not the effective area 41 is filled with the Hartmann image 61 is determined based on the result of the simulation. For example, the above determination can be made based on the center-to-center distance between the center of the effective area 41 at the target position and the center of the Hartmann image 61 (that is, the center on the outer periphery of the Hartmann image 61). For example, if the distance between the centers of the effective area 41 and the Hartmann image 61 is a large value with respect to the difference in radius between the effective area 41 and the Hartmann image 61, the effective area 41 is filled with the Hartmann image 61. Absent. On the other hand, if the center-to-center distance is a small value with respect to the difference in radius between the effective area 41 and the Hartmann image 61, the effective area 41 is filled with the Hartmann image 61. The determination method is not limited to this, and the determination may be performed using the positional relationship between the contours (outer circumferences) of the effective region 41 and the Hartmann image 61 at the target position, or based on other information. Determination may be performed.

  In step S25, if the effective region 41 at the target position is filled with the Hartmann image 61 as a result of the simulation, the control unit 800 determines that appropriate wavefront compensation control is possible at the target position (S25: Yes). ). In this case, the process proceeds to step S26. On the other hand, when the effective area 41 at the target position is not filled with the Hartmann image 61, the control unit 800 determines that proper wavefront compensation cannot be performed at the target position (S25: No). In this case, if the effective area 41 is set as the target position, it is difficult to obtain a good image. Therefore, in this embodiment, the second alignment is terminated without executing alignment guidance for the target position set in step S23, and the process proceeds to step S5 (the contents of step S5 will be described later). ).

  In step S26, the control unit 800 displaces the effective area 41 to the target position by driving and controlling the electric movement mechanism 610a. The control unit 800 commands the electric movement mechanism 610a with the movement amount and movement direction obtained in step S23. As a result, in this embodiment, the relative positional relationship between the eye E to be examined and the effective area 41 is adjusted by moving the chin rest 610. As a result, in the present embodiment, the effective region 41 is arranged at a position where coma aberration and spherical aberration in incident light to the effective region 41 are reduced.

  In the present embodiment, after step S26, the process returns to S22, and the positional relationship between the eye E and the effective area 41 is repeatedly finely adjusted. As a result, at the limit where the effective area 41 is filled with the Hartmann image (that is, at the limit where the effective area 41 is arranged in the Hartmann image 61), a position where the coma aberration is equal to or less than the threshold value, or coma is possible. The position of the effective area 41 with respect to the eye E is guided to a position that is suppressed as much as possible.

  Here, FIG. 10 shows the state of the wavefront of the fundus reflection light at the stage where the second alignment is completed. FIG. 10 is an aberration correction graphic 65 showing the state of the wavefront in the effective area 41 when the wavefront compensation unit is not driven. As described above, when the positional relationship between the eye E and the effective area 41 is finely adjusted by the second alignment, the aberration correction graphic 65 at the stage where the first alignment is performed is asymmetrical. It can be seen that wavefront distortion is reduced in the effective region 41. That is, as a result of the second alignment, the wavefront distortion to be compensated by the wavefront compensation device 72 is reduced. As a result, the wavefront compensation is easily performed well within the performance range of the wavefront compensation device 72. That is, for example, satisfactory wavefront compensation can be performed by using a device having a relatively small wavefront distortion that can be compensated.

  Here, when light enters the wavefront compensation device 72, diffracted light may be generated. For example, in the case of a device using liquid crystal such as LCOS as the wavefront compensation device 72, the incident light is diffracted at the end of the liquid crystal molecules constituting the pixel. Part of the incident light becomes a loss that is not effectively used for compensation due to diffraction. In addition, when the diffracted light is applied to the wavefront detection detector (in this embodiment, the wavefront sensor 73), the wavefront detection is affected. In the wavefront compensation device 72, the more distorted wavefront is compensated, the more diffracted light is generated. That is, as the wavefront distortion compensated by the wavefront compensation device 72 increases, it becomes difficult to perform wavefront compensation well, and the image quality of the first fundus image tends to deteriorate. In contrast, by performing the second alignment, light having a relatively small wavefront distortion is incident on the wavefront compensation device 72. For this reason, in the wavefront compensation device 72, diffracted light is hardly generated from incident light. As a result, it is easy to obtain a first fundus image with good image quality.

  In the present embodiment, the wavefront compensation device 72 is driven in a state where low-order aberrations are corrected by the second correction unit (the diopter correction unit 20 and the astigmatism correction unit 30). That is, the wavefront of the incident light with respect to the effective region 41 is reduced in advance by distortion due to low-order aberrations, so that the wavefront compensation by the wavefront compensation device 72 can be performed better.

  In the present embodiment, after the second alignment is completed, acquisition and display of the first fundus image and the second fundus image is started (S5). Thereafter, for example, the first and second fundus images are captured from several frames every second to several tens of frames, and are displayed on the monitor 85 as needed.

  Further, tracking is started after the completion of the second alignment (S6). For example, the tracking may correct a change in the photographing position of the first fundus image due to eye movement. The tracking may be for correcting a change in the positional relationship between the eye E to be examined and the effective area 41 due to eye movement. Of course, both of these may be used in combination. In the present embodiment, when tracking for correcting a change in the positional relationship between the eye E and the effective area 41 is performed, the control unit 800 sets the eye E and the effective area E set by the second alignment. (In other words, the positional relationship between the Hartmann image 61 and the effective region 41) is preferably maintained. In this case, the control unit 800 acquires reference information indicating the positional relationship between the eye E and the effective area 41 when the second alignment is completed. Then, after starting tracking, the control unit 800 acquires, as needed, fluctuation information indicating the positional relationship between the eye E to be examined and the effective area 41. Then, by adjusting the positional relationship between the eye E and the effective area 41 according to the difference between the variation information and the reference information, the positional relationship between the eye E and the effective area 41 is represented by the positional relationship indicated by the reference information. To correct. Here, the reference information and the variation information may be, for example, information based on the position information of the Hartmann image 61 and the position information of the effective area 41 (as a specific example, the center of the Hartmann image 61 and the effective area 41). It may be information indicating a positional relationship between each other). Further, the information may be information sequentially output from the imaging element of the anterior ocular segment observation unit 700 (for example, either the anterior ocular segment image itself or the position information of the pupil in the anterior ocular segment image). By performing tracking that maintains the positional relationship between the eye E to be examined and the effective region 41, it is easy to obtain a first fundus image that has been favorably wavefront compensated even if the eye moves. In order to adjust the positional relationship between the eye E and the effective area 41 in tracking, the positional relationship between the eye E and the wavefront compensation device 71 is relatively moved (mainly in the X and Y directions). Alternatively, the position of the effective region 41 in the wavefront compensation device 71 may be displaced.

  Thereafter, the first fundus image photographing process is executed (S7). In S7, the control unit 800 performs image shooting based on the input of the shooting trigger signal. For example, the control unit 800 stores a fundus cell image moving image or a still image acquired at the trigger signal input timing in the storage unit 801. As described above, in the present embodiment, the wavefront of the fundus reflection light is appropriately compensated by performing the second alignment. Therefore, in steps S5 and S7, the control unit 800 can obtain a first fundus image with good image quality.

  As mentioned above, although demonstrated based on embodiment, this indication is not limited to the said embodiment, A various deformation | transformation is possible.

  For example, in the above-described embodiment, the wavefront compensation device 72 is a liquid crystal modulation element, and in particular, a reflective LCOS or the like is used. However, the present invention is not limited to this. Other reflective wavefront compensation devices may be used. For example, a deformable mirror that is a form of MEMS (Micro Electro Mechanical Systems) may be used. In the deformable mirror, a large number of micromirrors are two-dimensionally arranged on the incident surface of the device. Each micromirror is displaced in the optical axis direction, thereby adjusting the optical path length difference of the entire wavefront to compensate the wavefront. Even in a deformable mirror, diffraction that occurs in a gap between adjacent mirrors causes a loss of compensation. As the gap between the mirrors in the optical axis direction increases, the loss due to diffraction increases. That is, for example, even in a deformable mirror, an image with good image quality is more easily obtained when a wavefront with less distortion is compensated. Therefore, even when the above embodiment is replaced with a deformable mirror, the same effect as the above embodiment can be obtained. Further, a transmissive wavefront compensation device may be used instead of the reflective wavefront compensation device. In the transmission type device, the wavefront aberration is compensated by transmitting the reflected light from the fundus.

  In the above embodiment, the case where the wavefront aberration of the eye E is measured using the wavefront sensor 73 provided in the optical system of the imaging apparatus 1 has been described. However, the imaging apparatus 1 only needs to have a configuration for measuring the wavefront aberration of the eye E based on the reflected light from the fundus, and the wavefront sensor 73 is not necessarily provided. For example, a case where the wavefront aberration is measured using the Phase Diversity method is conceivable. In this method, measurement light having a known wavefront aberration called Phase Diversity is intentionally given to a target optical system (here, eye E), and predetermined image processing is performed on an image obtained at that time. The wavefront aberration in the target optical system is estimated. In this case, for example, the light receiving element 56 provided in the fundus imaging optical system 100 can be used as a detector for wavefront aberration detection. That is, in this case, the fundus imaging optical system 100 can be shared with the aberration detection optical system 110. Of course, the detector may be provided separately from the light receiving element 56. Note that measurement light having Phase Diversity can be generated by controlling the wavefront compensation device 73 to a predetermined state, for example. Of course, it may be generated by other methods.

  Further, in the above-described embodiment, in the second alignment, the case where the relative positional relationship between the eye E and the effective area 41 is adjusted by driving and controlling the electric movement mechanism 610a to move the chin rest 610 will be described. did. However, in this case, the movement may be realized not by moving the chin rest 610 but by moving the photographing unit 500. In this case, the photographing apparatus 1 includes an electric movement mechanism that moves the photographing unit 500 with respect to the base. Further, the second alignment may be performed by moving the adaptive optics system inside the housing of the photographing unit 500 in the X and Y directions.

  In the above embodiment, in the second alignment, among the aberrations of the eye E to be obtained as a result of the calculation on the detection signal from the wavefront sensor 73, the coma aberration amount and the spherical aberration aberration amount are used. Thus, the positional relationship between the eye E and the effective area 41 was adjusted. However, the second alignment is not limited as long as the effective region 41 is disposed at a position where the wavefront distortion in the incident light to the effective region 41 is less. It is not necessary to adjust the position in consideration of the amount of aberration. The positional relationship between the eye E and the effective area 41 may be adjusted based on the amount of aberration that is different from both coma and spherical aberration. In this case, for example, the positional relationship between the eye E and the effective area 41 may be adjusted based on the aberration amount of aberration that appears symmetrically with respect to the meridian of the effective area such as coma. Further, for example, the positional relationship between the eye E and the effective region 41 based on the aberration amount of the third or higher order (for example, the third order, the fifth order, the seventh order, etc.) whose order is an odd number in the Zernike expansion. May be adjusted. In any case, the control unit 800 obtains a desired aberration amount by calculation based on the wavefront aberration detection signal, and induces the second alignment based on the aberration amount obtained by the calculation.

  In the above embodiment, the control unit 800 obtains the target position using the aberration amount obtained from the detection signal from the wavefront sensor 73 and induces alignment to the target position. However, it is not always necessary to obtain the target position. For example, the control unit 800 tries the position where the distortion of the wavefront of the incident light with respect to the effective region 41 is suppressed by obtaining the aberration amount at each position while switching the positional relationship between the eye E and the effective region 41. You may search by & error. In this case, for example, as a result of trial and error, alignment may be guided to a position where the obtained wavefront distortion is most suppressed.

  Further, in the above embodiment, in the second alignment (that is, the fine adjustment step of the positional relationship between the eye E and the effective area 41), the control unit 800 suppresses the aberration amount in the incident light to the effective area 41. The positional relationship between the eye E to be examined and the effective area 41 is adjusted repeatedly until it is done (in the above embodiment, equal to or less than the threshold). At this time, in the above-described embodiment, the control unit 800 performs control to relatively displace the eye E and the effective area 41 by the movement amount calculated based on the aberration amount of the eye E. However, the present invention is not necessarily limited thereto, and a configuration in which the eye E and the effective area 41 are relatively displaced by a certain amount of movement each time the process of S26 is performed may be employed.

  In the above embodiment, the positional relationship between the effective area 41 and the Hartmann image 61 at the target position is simulated, and whether or not the position of the eye E to be examined and the effective area 41 is adjusted according to the simulation result. We explained the case where However, the control for changing the alignment guidance content according to the simulation result is not limited to this. For example, when the effective area 41 is filled with the Hartmann image 61 at the target position as a result of the simulation, the control unit 800 guides alignment to the target position, and the effective area 41 is detected by the Hartmann image 61 at the target position. If not satisfied, the alignment may be guided to the extent that the effective area 41 is filled with the Hartmann image 61. In this case, for example, with respect to the movement direction obtained in S23, a movable amount (for example, a movable amount with respect to the pupil radius 1) in which the effective region 41 can move within a range where the effective region 41 is filled with the Hartmann image 61 is controlled. Part 800 seeks. Then, after the alignment is guided by the movable amount, the process may proceed to step S5.

  As a result of the simulation, when the effective area 41 is not filled with the Hartmann image 61 at the target position, the control unit 800 may narrow the effective area 41. As a result of the narrowing, there is a margin for displacing the effective area 41 within the range filled with the Hartmann image 61, so that the fine adjustment of the effective area can be performed. As a result, the image quality of the first fundus image may be improved.

  In the above embodiment, the control unit 800 guides the second alignment by automatically moving the positional relationship between the eye E and the effective area 41 by driving control of the electric movement mechanism 610a. explained. However, the configuration is not necessarily limited thereto, and a configuration in which the positional relationship between the eye E and the effective area 41 is manually adjusted in the second alignment may be employed. In this case, the moving mechanism that relatively moves the eye E and the effective area 41 does not need to be an electric mechanism such as the electric moving mechanism 610a, and may be a mechanical moving mechanism. This moving mechanism may be a mechanism that adjusts the relative positional relationship between the eye E and the imaging unit 500, for example. In the case of the mechanical type, as an operation unit to which an operation for relatively moving the eye E and the effective area 41 is input, for example, a joystick mechanically linked to a moving mechanism, an adjustment knob, or the like is used. Can be used. In this case, the control unit 800 may obtain the aberration amount of the eye E by calculating the detection signal from the wavefront sensor. Then, based on the calculation result of the aberration amount, the operation guide information for the second alignment may be displayed on the monitor 850. The guide information may be, for example, an index for illustrating the moving direction of the jaw table (or the imaging unit) in the XY directions. The index may be an arrow indicating the moving direction of the effective area 41 (or the operation direction of the examiner). Further, it may be a point indicating a target position on the anterior eye part image display screen, the aberration correction screen 60 or the like, a mark such as a cross, or the like. The control unit 800 displays the guide information on the monitor 850 to guide the second alignment by the examiner's operation.

  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 fundus front image of the eye E by receiving a light beam reflected by the fundus of the eye to be examined by a two-dimensional image sensor. Alternatively, an optical tomographic interference optical system (OCT optical system) that captures a tomographic image of the eye E by receiving interference light generated by the light beam reflected from the fundus of the eye to be examined and the reference light may be used.

DESCRIPTION OF SYMBOLS 20 Diopter correction part 30 Astigmatism correction part 41 Effective area 61 Hartmann image 72 Wavefront compensation device 73 Wavefront sensor 100 Fundus imaging optical system 110 Wavefront aberration detection optical system 400 Deflection part 610a Electric moving mechanism 800 Arithmetic control part 850 Monitor E Eye to be examined

Claims (3)

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 by controlling the wavefront of incident light;
An aberration detection optical system for detecting the wavefront aberration, wherein the measurement light is projected onto the eye to be examined, and the reflected light of the measurement light from the fundus of the eye to be examined is detected by a detector; ,
Adjusting means for adjusting a relative positional relationship between an eye to be examined and an effective region in which wavefront compensation is effective in the wavefront compensation device;
Based on the detection signal from the detector, the amount of aberration of the eye to be examined is calculated, and further, the guidance of alignment between the eye to be examined and the effective area by the adjusting means is based on the amount of aberration obtained as a result of the calculation. A fundus imaging apparatus with wavefront compensation, comprising: an arithmetic control unit to execute.   The calculation control means obtains an aberration amount of a third or higher order aberration having an odd order when the Zernike expansion is applied by the calculation, and induces the alignment using at least the aberration amount obtained by the calculation. The fundus imaging apparatus with wavefront compensation according to claim 1. The wavefront compensation device is an area where wavefront compensation is effective in the wavefront compensation device, out of wavefront measurement areas in which the wavefront aberration is measured by the aberration detection optical system on the anterior ocular conjugate plane of the eye to be examined. Which compensates for the wavefront in the effective region
The calculation control means simulates a positional relationship between the effective area and the wavefront measurement area in the result of alignment guidance based on the aberration amount obtained by the calculation, and according to the simulation result, the alignment control The fundus imaging apparatus with wavefront compensation according to claim 1 or 2, wherein the guidance content is changed.

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