JP6604020B2 - Fundus imaging apparatus and fundus imaging program - Google Patents

Fundus imaging apparatus and fundus imaging program Download PDF

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JP6604020B2
JP6604020B2 JP2015083686A JP2015083686A JP6604020B2 JP 6604020 B2 JP6604020 B2 JP 6604020B2 JP 2015083686 A JP2015083686 A JP 2015083686A JP 2015083686 A JP2015083686 A JP 2015083686A JP 6604020 B2 JP6604020 B2 JP 6604020B2
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optical
focus
imaging
fundus
control unit
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JP2016202249A5 (en
JP2016202249A (en
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直人 本多
幸弘 樋口
愛 ▲高▼谷
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株式会社ニデック
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Description

  The present disclosure relates to a fundus imaging apparatus and a fundus imaging program for imaging a fundus oculi to be examined.

  As an optical tomographic imaging apparatus that captures a tomographic image of a subject's eye, for example, an optical tomographic interferometer (Optical Coherence Tomography: OCT) using low-coherent light is known (see Patent Document 1).

  In such an apparatus, the examiner has focused the tomographic image using a focus state acquired by a front observation system such as an SLO optical system or a fundus camera optical system (see Patent Document 1). In another apparatus, the focus state of the OCT optical system is adjusted using the focus state of the front image, and then the focus is adjusted using the OCT optical system (see Patent Document 2).

JP 2012-213489 A JP 2009-291252 A

  However, in the case of the conventional method, the set imaging region may not be focused, and as a result, the image may not be acquired well.

  It is an object of one aspect of the present disclosure to provide a fundus imaging apparatus and a fundus imaging program that can capture an image with an improved focus state.

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

(1)
A tomographic imaging optical system for imaging a tomographic image of the fundus of the eye to be examined;
A front imaging optical system for imaging a front image of the fundus of the eye to be examined;
Control means for performing focus control of the tomographic imaging optical system with respect to the fundus of the eye based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system;
With
The fundus imaging apparatus, wherein the control means changes an optical system used for the focus control according to a focus region on the fundus of the eye to be examined.
(2)
A fundus imaging program executed in the fundus imaging apparatus,
The fundus imaging apparatus includes:
A tomographic imaging optical system for imaging a tomographic image of the fundus of the eye to be examined;
A front imaging optical system for imaging a front image of the fundus of the eye to be examined,
By being executed by the processor of the fundus imaging device,
A control step for performing focusing control of the tomographic imaging optical system with respect to the fundus of the eye to be examined based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system; A control step of changing the optical system used for the focus control according to the focus part,
The fundus imaging apparatus is configured to execute the fundus imaging apparatus.

1 is an external view of a fundus imaging apparatus according to an embodiment. It is a figure which shows the optical system and control system of the fundus imaging apparatus which concerns on a present Example. It is a figure which shows an example of an imaging | photography screen, and is an example at the time of setting to macular imaging | photography mode. It is a figure which shows an example of an imaging | photography screen, and is an example at the time of setting to a nipple imaging | photography mode. It is a flowchart which shows an example of the flow of operation | movement in the apparatus which concerns on a present Example. It is a figure explaining an example of the optimization control which concerns on a present Example. It is an example of an infrared fundus image captured by an image sensor, and is an example in the case of focusing on the macula. It is an example of the infrared fundus image imaged with an image sensor, and is an example when focusing on the nipple.

  Hereinafter, embodiments of the fundus imaging apparatus will be described. The fundus imaging apparatus 1 (see FIG. 1) includes, for example, a tomographic imaging optical system (for example, the OCT optical system 200), a front imaging optical system (for example, the imaging optical system 30), and a control unit (for example, the control unit 70, PC90) (see FIG. 2). The control unit may include a processor, and the fundus imaging apparatus may be operated by executing a program stored in the memory by the processor.

  The tomographic imaging optical system may include a first optical member for performing focusing on the fundus oculi Ef of the eye E to be examined. The tomographic imaging optical system may be configured to capture a fundus tomographic image Ef. The tomographic optical system is typically an OCT optical system, but is not limited thereto.

  The front imaging optical system may include a second optical member for performing focusing on the fundus oculi Ef. The front imaging optical system may be configured to capture a front image of the fundus oculi Ef. The front imaging optical system may be, for example, a fundus camera optical system based on a fundus camera or an SLO optical system based on an SLO (Scanning Laser Opthalmoscope). The front imaging optical system may be an optical system capable of capturing a front image or an optical system capable of observing a front image. Of course, the front imaging optical system may be configured to have both shooting and observation functions.

  The optical member for performing focusing may be, for example, an optical lens or a mirror unit. The optical member for performing focusing may be driven by a drive unit. The focus may be adjusted by moving the optical member in the optical axis direction by the actuator. That is, the optical member may be an optical member that can move in the optical axis direction. Further, the optical member for performing the focusing may be an optical member (for example, a liquid crystal lens) in which the focal position can be changed by electrical drive control without using a mechanical drive unit.

  The second optical member may have a configuration different from that of the first optical member. The first optical member and the second optical member may be arranged at different positions. The first optical member and the second optical member may be independently arranged in the tomographic imaging optical system and the front imaging optical system. In this case, each optical member may be arranged in the optical path after the tomographic imaging optical system and the front imaging optical system are separated. According to such a configuration, it is possible to adjust the focus of each optical system. The first optical member and the second optical member may be arranged at the same position, or the first optical member may also serve as the second optical member.

<Focus control>
The control unit performs focus control of the tomographic imaging optical system with respect to the fundus of the eye to be examined by driving the first optical member based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system. Also good. The control unit drives the second optical member based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system, thereby performing focus control of the front imaging optical system with respect to the eye to be examined. Good. The control unit may perform both the focusing control of the tomographic imaging optical system and the focusing control of the front imaging optical system, or may perform either focusing control.

  The control unit may change the focus control in accordance with the focus region on the fundus (see, for example, FIG. 6). As one aspect of changing the focusing control according to the in-focus part, for example, when focusing is performed on a preset imaging part, the control unit performs the focusing control according to the preset imaging part. May be changed. That is, the in-focus part may be defined as an imaging part that is imaged by at least one of the tomographic imaging optical system and the front imaging optical system. As another aspect, for example, when focus adjustment is performed on a target region set in the captured image, the control unit may change the focus control according to the target region.

  As an aspect of changing the focus control, the control unit may change the focus detection method. More specifically, the control unit may change the optical system used for focusing control in accordance with the focusing region. As a pattern for changing the optical system, for example, the control unit may change the light receiving optical system used for focusing control. For example, at least two patterns may be selected from the following methods according to the in-focus region. The control unit may perform focus adjustment based on an output signal from the tomographic imaging optical system. The control unit may perform focus adjustment based on an output signal from the front imaging optical system. The control unit may perform focus adjustment based on output signals from the tomographic imaging optical system and the front imaging optical system. In addition, the control unit may perform focus adjustment based on an output signal from an optical system different from the tomographic imaging optical system and the front imaging optical system.

  As a specific example, for example, the control unit performs first focusing control based on an output signal from the tomographic imaging optical system and first focusing control based on an output signal from the front imaging optical system. The control 2 may be changed according to the in-focus region on the fundus oculi Ef. For example, when the nipple is set as the in-focus part, the control unit may use the first control. When the macular part is set as the in-focus part, the control unit may use the second control. Thereby, the shift of the focus position due to the difference between the macula and the nipple is reduced, and the focus adjustment can be performed smoothly.

  As another aspect of changing the focus detection method, the control unit may change the detection light used for focus detection. In this case, the control unit may perform focus adjustment based on the focus index image projected on the fundus. The control unit may perform focus adjustment based on the captured fundus image (for example, a tomographic image or a front image).

  As one aspect of changing the focus control, the control unit may switch whether or not to add an offset to the focus position acquired based on the output signal from the optical system used for the focus control. In addition, each said focusing control may be performed independently, and may be performed combining these.

  As described above, for example, it is possible to cope with the shift of the in-focus position by the imaging region by the control according to the in-focus region. As a result, for example, focus adjustment can be performed smoothly regardless of the in-focus portion.

  In addition, as an example of a focus site | part, the macular part of the fundus oculi Ef and the nipple are mentioned. The control unit may change the focus control at least when the in-focus part is the macular part and when the in-focus part is the papilla. Of course, the present invention is not limited to this, and other examples of the in-focus part include the fundus center, the fundus periphery, and the like. In other words, the control unit may change the focusing control according to the change in the focusing region with respect to the surface direction of the fundus (direction orthogonal to the optical axis). Further, as another example of the in-focus part, a lesion part (for example, a retinal detachment part) is defined, and the control unit may change the in-focus control according to the lesion part.

  The focused part may be set in advance. For example, the control unit may receive an instruction signal for setting the in-focus portion by the tomographic imaging optical system or the front imaging optical system from an operation unit (for example, a user interface) operated by the examiner (operator). Good. The control unit may change the focusing control according to the received instruction signal. In this case, the imaging part may be defined as the in-focus part. Thereby, it is possible to favorably focus the image relating to the in-focus part set by the setting operation of the operator.

  Note that the in-focus portion may be associated with the fixation position of the eye E guided by the fixation target projection optical system (for example, the fixation target projection optical system 300). That is, the control unit may change the focus control according to the fixation position of the fixation target projection optical system. In this case, for example, a fixation position corresponding to the macula and a fixation position corresponding to the nipple may be set in advance.

  A configuration for determining the in-focus portion may be provided. For example, the control unit may determine a focus region on the fundus based on an output signal from an imaging optical system that images the eye E, and may change the focus control according to the determination result. Examples of the imaging optical system include a fundus tomographic imaging optical system, a fundus front imaging optical system, and an anterior ocular segment observation system. Thereby, for example, since the in-focus portion is automatically determined, the labor of the examiner can be reduced. In this case, it is possible to determine the in-focus portion by using a characteristic difference between the in-focus portions. For example, the in-focus region can be determined based on the position, shape, luminance distribution, size, etc. of the in-focus region in the fundus image. For example, the macular region is characterized in that it is formed slightly darker in the center of the fundus, and the nipple is characterized in that it is formed on the nasal side of the macula and the brightness of the depression is high. Further, the control unit may determine whether or not the focus index projected on the fundus is formed in a predetermined imaging region (for example, the nipple). Note that the control unit may determine the in-focus portion based on the fundus image after the focus is completed after the focus adjustment on the fundus image is completed. In this case, the control unit may determine whether or not the vicinity of the focus index is the nipple after detecting the position of the focus index. Further, the control unit may determine an in-focus portion on the fundus based on the pupil position of the anterior segment image. Thereby, the imaging region can be determined at the stage where the anterior segment image is acquired.

  In the control described above, the control unit may change the focus control according to the focus region on the fundus regarding the focus control in the tomographic imaging optical system. Further, the control unit may change the focus control in accordance with the focus portion on the fundus regarding the focus control in the front imaging optical system. Of course, the control unit may change the focusing control for both the tomographic imaging optical system and the front imaging optical system in accordance with the focused region.

  In the focusing control, the control unit is configured to drive a drive unit (for example, at least one of the first drive unit and the second drive unit) based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system. ), And an optical member (for example, at least one of the first optical member and the second optical member) may be automatically driven to the in-focus position. The control unit controls the display unit (for example, the display unit 75, the display unit 95, etc.) based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system, and an optical member (for example, the first imaging unit). Guide display for guiding the optical member or at least one of the second optical member) to the in-focus position may be performed. That is, the focus control in the present embodiment may be a control for driving the optical member so that the optical system is in focus (focus state) with respect to the fundus oculi Ef.

  When autofocus control and guide display are performed, focusing information (for example, a focused position) may be acquired based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system. The control unit may drive the optical member based on the acquired focusing information.

  When performing focus control of the tomographic imaging optical system based on the output signal from the front imaging optical system, the control unit interlocks with the driving of the second optical member of the front imaging optical system to One optical member may be driven. In addition, after the focus in the front imaging optical system is completed, the control unit acquires in-focus position information in the front imaging optical system from the memory, and the first optical unit is positioned at a position corresponding to the in-focus position in the front imaging optical system. The member may be driven.

  Note that the controller 70 may move one of the first optical member (for example, the lens 124) and the second optical member (for example, the lens 32) in conjunction with each other. For example, when the focus of the front imaging optical system is manually adjusted after the autofocusing of the front imaging optical system and the tomographic imaging optical system is completed, the first optical member may be interlocked according to the movement of the second optical member. Good. In other words, the control unit may perform separate driving in the auto focus and interlock the driving in the manual focus. In this case, the moving amount of each optical member may be set according to each optical system.

  As a result, when manual focus adjustment is performed, adjustment can be performed without breaking the automatically aligned positional relationship. Further, with such a configuration, the focus adjustment can be manually performed while observing the change in the focus state of both the fundus image and the OCT image, so that the adjustment is easier.

<Application to OCT>
When OCT is used as the tomographic imaging optical system, the OCT optical system includes, for example, a first focus optical member (for example, focusing lens 124), a measurement optical path, a reference optical path, and a detector (for example, detector 120). May be included. For example, the first focusing optical member may be moved in the optical axis direction by a first driving unit (for example, the driving unit 124a). The measurement optical path may include a first focus optical member and guide measurement light to the fundus oculi Ef. For example, the reference light path may generate reference light. The detector may detect an interference signal between the measurement light guided to the eye to be examined via the measurement optical path and the reference light from the reference optical path. The control unit may acquire a tomographic image of the fundus oculi Ef based on an output signal from the detector. The OCT optical system may be provided with an optical scanner (for example, the scanning unit 108) for scanning the fundus with measurement light. The control unit may acquire the B-scan tomographic image by scanning the measurement light in the transverse direction using an optical scanner. The control unit may acquire the three-dimensional OCT data by scanning the measurement light two-dimensionally (XY direction) using an optical scanner. The control unit may acquire OCT motion contrast data by comparison between tomographic images acquired at different times.

  Regarding the focus control of the OCT optical system, for example, the control unit may switch between the first autofocus control and the second autofocus control in accordance with the focus region.

  As the first autofocus control, for example, the control unit may acquire first focus position information based on an output signal from a detector of the OCT optical system. The first focus position information corresponds to, for example, a focus position with respect to the fundus of the OCT optical system. The control unit may drive the first focus optical member of the OCT optical system to a position corresponding to the first focus position information.

  When performing the focus control based on the output signal from the detector of the OCT optical system, the control unit may execute the focus control based on the tomographic image acquired by the OCT optical system. The control unit may perform focus control based on an interference signal output directly from the detector of the OCT optical system.

  As the second autofocus control, the control unit may acquire the second focus position information based on the light reception signal output from the light receiving element of the front imaging optical system. The second focus position information corresponds to, for example, focus position information with respect to the fundus of the front imaging optical system. The control unit may drive the first focusing optical member of the OCT optical system to a position corresponding to the second in-focus position information.

  The OCT optical system may include, for example, an adjustment optical member (for example, the reference mirror 131) configured to adjust the optical path length difference between the measurement light and the reference light. The adjustment optical member may be movable in the optical axis direction by a drive unit (for example, the drive unit 150). For example, the adjustment optical member may be disposed in the measurement optical path or the reference optical path in order to adjust the optical path length difference between the measurement light and the reference light. The optical path length difference may be adjusted by changing the optical path length of the measuring light or the reference light using the adjusting optical member. The adjustment optical member may be moved by, for example, a drive unit (for example, the drive unit 150).

  The control unit may control the drive unit based on an output signal from the detector of the OCT optical system and automatically move the adjustment optical member. In this case, the control unit searches for the position of the adjustment optical member from which the tomographic image of the fundus of the eye to be examined is acquired based on the output signal from the detector before moving the first focus optical member. Good. For example, after the first focusing optical member is moved to the in-focus position, the control unit controls the driving unit based on the output signal from the detector, and re-adjusts the position of the optical path length adjusting optical member. May be. The control unit may change the timing for operating the automatic adjustment of the adjustment optical member according to the in-focus portion.

<Front imaging optical system>
When a front imaging optical system is used as the front imaging optical system, the front imaging optical system includes, for example, a second focus optical member (for example, a lens 32) and a light receiving element (for example, (for imaging) imaging element 35, ( It may include an imaging element 38) for observation). The second focus optical member may be moved in the optical axis direction by, for example, a second drive unit (for example, drive unit 49). For example, the light receiving element may receive reflected light from the fundus via the second focusing optical member. For example, the front imaging optical system may capture a front image of the fundus oculi Ef based on an output signal from the light receiving element.

  The front imaging optical system may be provided with an index projection optical system. The index projection optical system may be configured to project a focus index on the fundus oculi Ef. The control unit may perform focusing control based on the focus index received by the light receiving element. Focus control can be performed in a short time by focus detection using a focus index. Note that the control unit may obtain the second in-focus position information based on, for example, a front image captured by the front imaging optical system.

  When obtaining the in-focus position based on the tomographic image, the front image, and the interference signal, the control unit may calculate an evaluation value for detecting the in-focus state with respect to the fundus and obtain the in-focus position from the evaluation value. . Note that the evaluation value may be, for example, at least one of a histogram, a peak position, a luminance distribution, and the like (see, for example, JP2009-291252A and JP2012-213489A).

<Fixed target projection optical system>
A fixation target projection optical system (for example, the fixation target projection optical system 300) may be arranged in the fundus imaging apparatus. The fixation target projection optical system may be an optical system for guiding the line-of-sight direction of the eye E. The fixation target projection optical system may include a plurality of fixation targets to be presented to the eye E and guide the eye E in a plurality of directions.

  For example, the fixation target projection optical system may include a visible light source that emits visible light, and may change the presentation position of the fixation target two-dimensionally. Thereby, the line-of-sight direction is changed, and as a result, the imaging region is changed. That is, the imaging region is changed according to the position of the fixation target with respect to the imaging optical axis.

<Application to other optical systems>
In the above description, the tomographic imaging optical system and the front imaging optical system have been described as examples. However, the present embodiment is not limited thereto, and the present embodiment can be applied to any ophthalmic imaging apparatus including a plurality of imaging optical systems. It is. The ophthalmic imaging apparatus includes, for example, a first imaging optical system (for example, an OCT optical system) for imaging a subject's eye (for example, the anterior eye portion and the fundus) with a first imaging method, You may provide with the 2nd imaging optical system (for example, front imaging optical system) for imaging with an imaging system. The control unit may perform focusing control of the first imaging optical system with respect to the eye to be inspected based on an output signal from at least one of the first imaging optical system and the second optical system. The control unit may change the focusing control in accordance with the focused region of the eye to be examined. In this case, for example, a first imaging optical system that captures a cell image of the fundus using a wavefront compensation device and a second imaging optical system that captures a fundus image having a larger imaging range than the first imaging optical system are provided. The present embodiment may be applied to the apparatus.

  The present embodiment can also be applied to an ophthalmic imaging apparatus that includes an imaging optical system and a detection optical system. The imaging optical system may include, for example, an optical member that is driven by a driving unit and performs focusing on the eye E (for example, the fundus oculi Ef or the anterior eye portion). The imaging optical system may be configured to image the eye E (for example, the fundus oculi Ef or the anterior eye segment). As the imaging optical system, for example, a tomographic imaging optical system may be used.

  The detection optical system may be configured to detect a focus state of the imaging optical system with respect to the fundus oculi Ef. The detection optical system may include a light receiving element that receives reflected light from the fundus. In this case, the detection optical system may be configured differently from the imaging optical system.

  The control unit may perform focusing control of the imaging optical system with respect to the fundus oculi Ef by driving the optical member based on an output signal from at least one of the imaging optical system and the detection optical system.

  When a tomographic imaging optical system is used as the imaging optical system, for example, a fundus front imaging optical system may be used as the detection optical system.

<Example>
Hereinafter, an example according to the present embodiment will be described with reference to the drawings. In the present embodiment, the axial direction of the subject's eye (eye E) will be described as the Z direction, the horizontal direction as the X direction, and the vertical direction as the Y direction. The surface direction of the fundus may be considered as the XY direction.

  As shown in FIG. 1, the fundus imaging apparatus 1 of the present embodiment mainly includes, for example, a base 4, an imaging unit (apparatus main body) 3, a face support unit 5, and an operation unit 74. The photographing unit 3 may house an optical system described later. The imaging unit 3 may be provided so as to be movable in a three-dimensional direction (XYZ) with respect to the eye E. The face support unit 5 may be fixed to the base 4 in order to support the subject's face.

  The imaging unit 3 may be moved relative to the eye E in the left-right direction, the up-down direction (Y direction), and the front-rear direction by the XYZ drive unit 6.

  The joystick 74a is used as an operation member operated by the examiner to move the photographing unit 3 with respect to the eye E. Of course, it is not limited to the joystick 74a, and may be another operation member (for example, a touch panel, a trackball, etc.).

  For example, the operation unit once transmits an operation signal from the examiner to the control unit 70. In this case, the control unit 70 may send an operation signal to the personal computer 90 described later. For example, the personal computer 90 sends a control signal corresponding to the operation signal to the control unit 70. For example, when the control unit 70 receives the control signal, the control unit 70 may perform various controls based on the control signal.

  For example, the photographing unit 3 is moved with respect to the eye E by operating the joystick 74a. Further, by rotating the rotary knob 74b, the XYZ driving unit 6 is driven and the photographing unit 3 is moved in the Y direction.

  The imaging unit 3 may be provided with a display unit 75 (for example, the examiner side). The display unit 75 may display, for example, a fundus observation image, a fundus photographing image, and an anterior eye observation image. The display unit 75 may include a touch panel that also serves as the operation unit 74.

  Note that the fundus imaging apparatus 1 of the present embodiment is connected to a personal computer (hereinafter referred to as a PC) 90. For example, a display unit 95, an operation unit (keyboard, mouse, etc.) 96, a control unit 70, and the like may be connected to the PC 90.

<Optical system>
As shown in FIG. 2, the optical system of the present embodiment mainly includes an illumination optical system 10, an imaging optical system (front imaging optical system) 30, and an interference optical system (hereinafter also referred to as OCT optical system) 200. The photographing optical system 30 is used as a fundus camera optical system for obtaining a fundus image by photographing the fundus (for example, a non-mydriatic state). For example, an infrared fundus image is acquired by infrared light, and a color fundus image is acquired by visible light. The imaging optical system 30 may capture a fluorescent fundus image with predetermined excitation light. The OCT optical system 200 obtains a tomographic image of the fundus of the eye to be examined non-invasively using an optical interference technique. Further, the optical system may include a focus index projection optical system 40, an alignment index projection optical system 50, an anterior ocular segment observation optical system 60, and a fixation target projection optical system 300.

<Illumination optics>
The illumination optical system 10 includes, for example, an observation illumination optical system and a photographing illumination optical system. The photographing illumination optical system mainly includes a light source 14, a condenser lens 15, a ring slit 17, a relay lens 18, a mirror 19, a black spot plate 20, a relay lens 21, a perforated mirror 22, and an objective lens 25. The photographing light source 14 may be a flash lamp or the like. The black spot plate 20 has a black spot at the center.

  The observation illumination optical system mainly includes an optical system from the light source 11, the infrared filter 12, the condenser lens 13, the dichroic mirror 16, and the ring slit 17 to the objective lens 25. The light source 11 may be, for example, a halogen lamp. For example, the infrared filter 12 transmits near infrared light having a wavelength of 750 nm or more. The dichroic mirror 16 is disposed, for example, between the condenser lens 13 and the ring slit 17. Further, the dichroic mirror 16 has a characteristic of reflecting light from the light source 11 and transmitting light from the photographing light source 14, for example.

<Photographing optical system>
In the photographing optical system (front photographing optical system) 30, for example, an objective lens 25, a photographing aperture 31, a focusing lens 32, an imaging lens 33, and an image sensor 35 are mainly disposed. The photographing aperture 31 is located in the vicinity of the aperture of the perforated mirror 22. The focusing lens 32 is movable in the optical axis direction. The image sensor 35 can be used for imaging having sensitivity in the visible range, for example. For example, the photographing aperture 31 is disposed at a position substantially conjugate with the pupil of the eye E with respect to the objective lens 25. The focusing lens 32 is moved in the optical axis direction by a moving mechanism 49 including a motor, for example.

  Further, a dichroic mirror 34 having a characteristic of reflecting part of infrared light and visible light and transmitting most of visible light is disposed between the imaging lens 33 and the image sensor 35. In the reflection direction of the dichroic mirror 34, an observation imaging element 38 having sensitivity in the infrared region is disposed. Instead of the dichroic mirror 34, a flip-up mirror may be used. For example, the flip-up mirror is inserted into the optical path during fundus observation, and is retracted from the optical path during fundus imaging.

  In addition, between the objective lens 25 and the perforated mirror 22, for example, an insertable / detachable dichroic mirror (wavelength selective mirror) 24 as an optical path branching member is provided obliquely. The dichroic mirror 24 reflects, for example, the wavelength light of the OCT measurement light and the wavelength light (center wavelength 940 nm) of the alignment index projection optical system 50 and the anterior ocular segment illumination light source 58.

  The dichroic mirror 24 has a characteristic of transmitting a wavelength of 900 nm or less including the light source wavelength (center wavelength 880 nm) of the wavelength light of the fundus observation illumination, for example. When photographing is performed by the photographing optical system 30, the dichroic mirror 24 is flipped up by the insertion / removal mechanism 66 and retracted out of the optical path. The insertion / removal mechanism 66 can be composed of a solenoid and a cam.

  Further, the optical path correction glass 28 is disposed on the image pickup element 35 side of the dichroic mirror 24 so as to be able to be flipped up by driving the insertion / removal mechanism 66. When the optical path is inserted, the optical path correction glass 28 has a role of correcting the position of the optical axis L1 shifted by the dichroic mirror 24.

  The light beam emitted from the observation light source 11 is converted into an infrared light beam by the infrared filter 12 and reflected by the condenser lens 13 and the dichroic mirror 16 to illuminate the ring slit 17. The light transmitted through the ring slit 17 reaches the perforated mirror 22 through the relay lens 18, the mirror 19, the black spot plate 20, and the relay lens 21. The light reflected by the perforated mirror 22 passes through the correction glass 28 and the dichroic mirror 24, and once converges near the pupil of the eye E by the objective lens 25, and then diffuses to illuminate the fundus Ef.

  Reflected light from the fundus includes an objective lens 25, a dichroic mirror 24, a correction glass 28, an aperture of a perforated mirror 22, an imaging aperture 31, a focusing lens 32, an imaging lens 33, a dichroic mirror 34, a dichroic mirror 37, and a relay lens. An image is formed on the image sensor 38 via 36. The output of the image sensor 38 is input to the control unit 70, and the control unit 70 displays a fundus observation image of the eye to be inspected imaged by the image sensor 38 on the display unit 75 (see FIG. 3).

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

<Focus index projection optical system>
The focus index projection optical system 40 mainly includes an infrared light source 41, a slit index plate 42, two declination prisms 43, a projection lens 47, and a spot mirror 44 obliquely provided in the optical path of the illumination optical system 10. The two declination prisms 43 are attached to the slit target plate 42. The spot mirror 44 is provided obliquely in the optical path of the illumination optical system 10. The spot mirror 44 is fixed to the tip of the lever 45. The spot mirror 44 is normally inclined to the optical axis, but is retracted out of the optical path by rotation of the rotary solenoid 46 at a predetermined timing before photographing.

  The spot mirror 44 is arranged at a position conjugate with the fundus of the eye E. The light source 41, the slit indicator plate 42, the deflection prism 43, the projection lens 47, the spot mirror 44 and the lever 45 are moved in the optical axis direction by the moving mechanism 49 in conjunction with the focusing lens 32. Further, the light flux of the slit index plate 42 of the focus index projection optical system 40 is reflected by the spot mirror 44 via the deflection prism 43 and the projection lens 47, and then the relay lens 21, the perforated mirror 22, the dichroic mirror 24, The light is projected onto the fundus of the eye E through the objective lens 25. When the fundus is out of focus, the focus index images (hereinafter sometimes abbreviated as index images) S1 and S2 are projected onto the fundus in a state of being separated according to the shift direction and shift amount (see FIG. 3 (a)). On the other hand, when the focus is achieved, the index images S1 and S2 are projected onto the fundus in a matched state (see FIG. 3B). The index images S1 and S2 are taken together with the fundus image by the image sensor 38.

  <Fixation Target Projection Optical System> The fixation target projection optical system 300 may include a fixation target 302. The fixation target projection optical system 300 may be configured to project the fixation target onto the fundus oculi Ef. The fixation target projection optical system 300 may have a configuration in which the fixation target presentation position is variable. By changing the presentation position, the eye E is guided in a predetermined line-of-sight direction.

  As the fixation target projection optical system, for example, a configuration in which the fixation position is adjusted by the lighting positions of light sources (for example, LEDs) arranged in a matrix, and a display panel that adjusts the fixation position by changing the display position (for example, , Liquid crystal panels), various configurations such as a configuration in which light from a light source is scanned by an optical scanner, and a fixation position is adjusted by lighting control of the light source. The fixation target projection optical system may be an internal fixation lamp type or an external fixation lamp type.

  The light flux from the fixation target 302 passes through the lens 304, the dichroic mirror 37, the dichroic mirror 34, the imaging lens 33, the focusing lens 32, the perforated mirror 22, the dichroic mirror 24, and the objective lens 25 and is projected onto the fundus oculi Ef. The The subject visually recognizes the projected light beam as a fixation target.

<Alignment index projection optical system>
The alignment index projection optical system 50 projects an alignment index beam onto the eye E. In the alignment index projection optical system 50, as shown in the diagram in the lower left dotted line in FIG. 2, a plurality of infrared light sources are arranged at 45 degree intervals on a concentric circle with the photographing optical axis L1 as the center. The ophthalmologic photographing apparatus in the present embodiment mainly includes a first target projection optical system (0 degrees and 180) and a second target projection optical system.

  The first index projection optical system has an infrared light source 51 and a collimating lens 52. The second index projection optical system is arranged at a different position from the first index projection optical system and has six infrared light sources 53. The infrared light sources 51 are arranged symmetrically with respect to a vertical plane passing through the photographing optical axis L1.

  In this case, the first index projection optical system projects an index at infinity on the cornea of the eye E from the left-right direction. The second index projection optical system is configured to project a finite index on the cornea of the eye E from the vertical direction or the oblique direction. In FIG. 2, for convenience, the first index projection optical system (0 degrees and 180 degrees) and only a part of the second index projection optical system (45 degrees and 135 degrees) are shown. .

<Anterior segment observation optical system>
An anterior ocular segment observation (imaging) optical system 60 that images the anterior segment of the eye E to be examined is provided on the reflection side of the dichroic mirror 24 with a dichroic mirror 61, a diaphragm 63, a relay lens 64, and a two-dimensional imaging element (light receiving element: hereinafter). , Which may be abbreviated as “image sensor 65”). The image sensor 65 has infrared sensitivity. The imaging element 65 also serves as an imaging means for detecting the alignment index, and the anterior segment illuminated by the anterior segment illumination light source 58 that emits infrared light and the alignment index are imaged. Reflected light from the anterior segment is received by the image sensor 65 from the objective lens 25, the dichroic mirror 24, and the dichroic mirror 61 via the optical system of the relay lens 64. The alignment light beam from the alignment index projection optical system 50 is projected onto the eye cornea to be examined. The cornea reflection image is received (projected) by the image sensor 65 through the objective lens 25 to the relay lens 64.

  The output of the two-dimensional image sensor 65 is input to the control unit 70. The anterior segment image captured by the two-dimensional image sensor 65 is displayed on the display unit 75 (see FIGS. 5 and 6). The anterior ocular segment observation optical system 60 also serves as a detection optical system for detecting the alignment state of the apparatus main body with respect to the eye to be examined.

<OCT optical system>
Returning to FIG. The OCT optical system 200 has a device configuration of a so-called ophthalmic optical coherence tomography (OCT) and takes a tomographic image of the eye E. The OCT optical system 200 divides light emitted from the measurement light source 102 into measurement light and reference light by a coupler (light splitter) 104. The OCT optical system 200 guides measurement light to the fundus oculi Ef and guides reference light to the reference optical system 110. The measurement light reaches the scanning unit 108 via the collimator lens 123 and the focus lens 124, and the reflection direction is changed by driving two galvanometer mirrors, for example. The measurement light reflected by the scanning unit 108 is reflected by the dichroic mirror 24 via the relay lens 109 and then condensed on the fundus oculi Ef via the objective lens 25. Interference light obtained by combining the measurement light reflected by the fundus oculi Ef and the reference light is received by the detector (light receiving element) 120.

  The detector 120 detects an interference state between the measurement light and the reference light. In the case of Fourier domain OCT, the spectral intensity of the interference light is detected by the detector 120, and a depth profile (A scan signal) in a predetermined range is obtained by Fourier transform on the spectral intensity data. Examples include Spectral-domain OCT (SD-OCT) and Swept-source OCT (SS-OCT).

  In the case of Spectral-domain OCT (SD-OCT), for example, a broadband light source is used as the light source 102, and a spectrometer (spectrometer) is used as the detector 120.

  In the case of Swept-source OCT, for example, a variable wavelength light source is used as the light source 102, and a single photodiode is used as the detector 120 (balance detection may be performed). Moreover, Time-domain OCT (TD-OCT) may be used.

  The scanning unit 108 scans light emitted from the measurement light source on the fundus of the eye to be examined. For example, the scanning unit 108 scans the measurement light two-dimensionally (XY direction (transverse direction)) on the fundus. The scanning unit 108 is disposed at a position substantially conjugate with the pupil. The scanning unit 108 is, for example, two galvanometer mirrors, and the reflection angle thereof is arbitrarily adjusted by the driving unit 151.

  The reflection (advance) direction of the light beam emitted from the light source 102 is changed and scanned in an arbitrary direction on the fundus. The scanning unit 108 may be configured to deflect light. For example, in addition to a reflective mirror (galvano mirror, polygon mirror, resonant scanner), an acousto-optic device (AOM) that changes the traveling (deflection) direction of light is used.

  The reference optical system 110 is configured to generate reference light. The reference light is combined with the reflected light acquired by the reflection of the measurement light at the fundus oculi Ef. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type.

  The reference optical system 110 may change the optical path length difference between the measurement light and the reference light by moving the optical member in the reference light path. For example, the reference mirror is moved in the optical axis direction. The configuration for changing the optical path length difference may be arranged in the measurement optical path of the measurement optical system.

  More specifically, the reference optical system 110 may include, for example, a collimator lens 129, a reference mirror 131, and a reference mirror driving unit 150. The reference mirror driving unit 150 is disposed in the reference optical path and is configured to be movable in the optical axis direction so as to change the optical path length of the reference light. The light is reflected by the reference mirror 131 and returned to the coupler 104 again and guided to the detector 120. As another example, the reference optical system 110 is formed by a transmission optical system (for example, an optical fiber), and guides the light from the coupler 104 to the detector 120 by transmitting the light without returning.

<Control unit>
Next, the control system of this embodiment will be described. The control unit 70 includes an image sensor 65 for anterior segment observation, an image sensor 38 for infrared fundus observation, a display unit 75, an operation unit 74, each light source, various drive units, and an image sensor 35. And the PC 90 may be connected. In order to avoid complication, in FIG. 2, a part of the lines indicating the connection between the image sensor, each light source, the driving unit, and the control unit 70 is omitted.

  The control unit 70 may display the anterior ocular segment observation image captured by the imaging element 65 and the infrared fundus observation image captured by the imaging element 38 on the display unit 75 of the main body. The control unit 70 may drive and control the OCT optical system 200 and the imaging optical system 30 to acquire the OCT image and the infrared fundus image for each frame. The control unit 70 may display-control the display unit 75 and update the OCT image and the infrared fundus image on the display unit 75 as needed.

  The PC 90 may include a CPU as a processor, a memory (nonvolatile memory) as a storage unit, and the like. The PC 90 may be connected to an operation unit (for example, a mouse, a keyboard, etc.) 96, a display unit 95, and the like. The display unit 95 may be a touch panel or may be used as an operation unit. The operation unit 96 may be configured as a user interface, and may be used, for example, for device operation control and various settings. The PC 90 may accept an operation signal from the operation unit.

  The PC 90 may transmit a control signal for controlling the ophthalmologic photographing apparatus 1 to the control unit 70. The memory of the PC 90 is a non-transitory storage medium that can retain stored contents even when power supply is interrupted. For example, a hard disk drive, a flash ROM, a USB memory detachably attached to the PC 90, an external server, or the like can be used as the memory. The memory stores an imaging control program for controlling imaging of front images and tomographic images by the fundus imaging apparatus 1.

  The PC 90 (more specifically, the processor (for example, CPU) of the PC 90 may acquire a light reception signal from the detector 120 via the control unit 70. The PC 90 performs an arithmetic process on the light reception signal from the detector 120. By doing so, a tomographic image may be generated.

  For example, in the case of Fourier domain OCT, the PC 90 receives the output signal from the detector 120 and processes the spectral signal including the interference signal at each wavelength. The PC 90 processes the spectrum signal to obtain internal information of the eye to be examined (for example, data of the eye to be examined (depth information) regarding the depth direction). More specifically, the spectrum signal (spectrum data) is converted into a function I (k) that is equally spaced with respect to the wave number k (= 2π / λ). The PC 90 obtains a signal distribution in the depth (Z) region by Fourier-transforming the spectrum signal in the wave number k space.

  In the above description, the PC 90 and the apparatus main body are separately arranged, but the apparatus main body and the PC 90 may be integrated. In this case, the control unit 70 may also use the function of the PC 90.

<Control action>
The control operation of the apparatus having the above configuration will be described.

  As preparation for imaging, for example, an imaging region by OCT is set. The control unit 70 may accept an instruction signal from an operation unit (for example, the operation unit 96) for setting an imaging region. The control unit 70 may set an imaging region of a tomographic image captured by the OCT optical system 200 based on the instruction signal. As the imaging region, for example, either the macular portion of the fundus or the nipple may be selectable. In addition, a wide area including the macula and the nipple may be settable. Moreover, the fundus peripheral part not including the macula and the nipple may be settable.

  As another preparation, a scanning pattern by OCT may be set. The control unit 70 may receive an instruction signal from an operation unit (for example, the operation unit 96) for setting a scanning pattern. The control unit 70 may set a scanning pattern for scanning the fundus using the OCT optical system 200 based on the instruction signal. Examples of the scan pattern to be set include line scan, multi-scan (for example, a plurality of line scans separated from each other), cross scan, map scan (for example, raster scan), and the like.

  The imaging region to be set may be associated with the fixation position of the fixation target projection optical system 300. The control unit 70 can control the fixation target projection optical system 300 according to the set imaging region. As a result, the line-of-sight direction of the eye to be examined is changed according to the imaging region.

  For example, the control unit 70 may set the fixation position so that the imaging region is positioned at the center of the imaging region. As a result, the imaging region may be arranged on the optical axis L1. Of course, the imaging region does not need to be strictly disposed on the optical axis L1, and the vicinity of the imaging region may be disposed. Further, it is not always necessary that the center of the imaging region is arranged on the optical axis L1.

  When the macular portion is set as the imaging region, for example, the fixation position may be set so that the macular portion is positioned at the center of the imaging region. In this case, the fixation position may be set at the center (on the optical axis). When the nipple is set as the imaging region, for example, the fixation position may be set so that the nipple is positioned at the center of the imaging region. In this case, the fixation position may be set on the nose side and slightly on the upper side. Note that the fixation position may be a symmetrical relationship between the left and right eyes.

  The setting of the imaging region may be set in association with the OCT scanning pattern. An example is shown below. 3 and 4 are diagrams illustrating an example of the photographing screen. FIG. 3 is an example when the macular photographing mode is set, and FIG. 4 is an example when the papillary photographing mode is set.

  In the setting screen, a plurality of first buttons 400 (for example, a macular line, a macular cross, a macular map, etc.) in which a macular part and a scanning pattern are associated are provided. In addition, a plurality of second buttons 410 (for example, a nipple line, a nipple cross, and a nipple map) in which a nipple and a scanning pattern are associated are provided. When any of these buttons is operated by the examiner, the control unit 70 can set an imaging region and a scanning pattern according to the operation instruction signal.

  The control unit 70 displays the front image 420, the index 425, and the tomographic image 430 acquired by the imaging optical system 30 on the display unit 75. The index 425 is an index that represents the measurement position (acquisition position) of the tomographic image on the front image 420 and the scan pattern. That is, when the scan pattern is changed, the control unit 70 changes the display pattern of the index based on the changed scan pattern. The index 425 is electrically superimposed and displayed on the front image on the display unit 75. The PC 90 may display the same content as the content displayed on the display unit 75 on the display unit 95.

  For example, the tomographic image 430 is displayed on the display unit 75 as the tomographic image 430. Note that the control unit 70 may display a plurality of tomographic images on the display unit 75 according to the scan pattern.

<Shooting procedure>
After the shooting conditions are set as described above, the process proceeds to the shooting operation. Hereinafter, an example of the operation using the above apparatus will be described. FIG. 5 is a flowchart illustrating an example of an operation flow in the present apparatus. The examiner instructs the subject to gaze at the fixation target. The examiner observes the anterior ocular segment observation image on the display unit 75. The examiner performs alignment using the joystick 74 so that the optical axis comes to the center of the pupil. When the alignment with respect to the eye E is completed, a fundus front image (infrared fundus image) is acquired, and a front image 420 appears on the display unit 75.

  Next, optimization control is performed so that the fundus site desired by the examiner can be observed with high sensitivity and high resolution. In this embodiment, as control for optimizing the OCT optical system 200, optical path length adjustment, focus adjustment, and polarization state adjustment (polarizer adjustment) may be performed. Further, as the optimization control of the photographic optical system 30, at least focus adjustment may be performed.

  The examiner inputs a trigger signal for starting optimization control by operating the optimization start switch (Optimize switch) 74c or the operation unit 96. The control unit 70 starts optimization based on the trigger signal.

  After the optimization is completed, when the operation unit 96 is operated by the examiner and an imaging execution trigger is input, the control unit 70 captures (captures) a fundus tomographic image and stores the tomographic image in the memory of the PC 90. . Note that the control unit 70 may automatically take a tomographic image based on a signal indicating that the optimization control has been completed.

<Optimization control>
FIG. 6 is a diagram illustrating an example of optimization control according to the present embodiment. The control unit 70 may set the positions of the reference mirror 131 and the focusing lens 124 to initial positions as control for initialization. After the initialization is completed, the control unit 70 moves the reference mirror 131 in one direction from the set initial position in a predetermined step to perform the first optical path length adjustment (first automatic optical path length adjustment). If a fundus tomographic image has already been acquired, the initialization, the first optical path length adjustment, and the like need not be performed.

  Further, in parallel with the first optical path length adjustment, the control unit 70 performs focus adjustment (first focus) of the imaging optical system 30 with respect to the subject's eye based on the infrared fundus image output from the image sensor 38. May be.

  The controller 70 may adjust the focus of the OCT optical system 200 based on the focus information of the imaging optical system 30 after the focus adjustment of the imaging optical system 30 based on the infrared fundus image is completed (second focus). ). Further, the control unit 70 may adjust the focus of the OCT optical system 200 based on the focus information of the OCT optical system 200 (third focus).

  Note that the in-focus position may be a position where the contrast of the tomographic image acceptable as the observation image can be acquired, and is not necessarily the optimum position in the focus state.

  Then, after the focus adjustment is completed, the control unit 70 moves the reference mirror 131 again in the optical axis direction, and performs the second optical path length adjustment for readjustment of the optical path length (fine adjustment of the optical path length). After completing the second optical path length adjustment, the control unit 70 drives the polarizer 133 for adjusting the polarization state of the reference light, and adjusts the polarization state of the measurement light.

  7 and 8 are examples of infrared fundus images captured by the image sensor 38, and focus index images S1 and S2 by the focus target projection optical system 40 are projected at the center of the fundus image. FIG. 7 shows an example of focusing on the macula, and FIG. 8 shows an example of focusing on the nipple.

  Here, the focus index images S1 and S2 are separated when they are not in focus (see FIGS. 7A and 7A), and are projected in agreement when they are in focus (FIG. 7). (B), see FIG. 8 (b)). The control unit 70 may detect the index images S1 and S2 by image processing and obtain the separation information. The control unit 70 may control the driving of the moving mechanism 49 based on the separation information of the index images S1 and S2, and may move the lens 32 so that the fundus is in focus. For convenience of explanation, the focus lever is not shown.

  Here, in the first focus adjustment, when the fundus is in focus, the focus index images S1 and S2 are matched on the optical axis L1. When the imaging part is arranged on the optical axis L1 by the above-described line-of-sight guidance control, the focus index images S1 and S2 are matched on the imaging part (FIGS. 7 and 8). As a result, the focus of the imaging optical system 30 is in a state where it is in alignment with the imaging region.

  More specifically, when a macular portion is set as an imaging region, a split index is projected on or near the macula. As a result, when the split index is matched, the photographing optical system 30 is focused on the macular region.

  When the nipple is set as the imaging part, the split index is projected on the depression of the nipple or in the vicinity of the depression. As a result, when the split index is matched, the photographing optical system 30 is focused on the recessed area.

  Due to the structure of the eye, a recess is formed on the back side of the macular region. When the focus position in the optical axis direction is compared between the macular portion and the nipple, when focus adjustment is performed on the nipple, the focus is adjusted to the back side of the macular region. That is, when performing macular photography and nipple photography on the same eye, the focusing lens at the focused position is usually arranged at a different position.

  The shift of the focus position can affect the OCT imaging. That is, when the focusing lens 124 is automatically moved using the focus position information in the photographing optical system 30, the focus position of the OCT optical system 200 depends on the focus position in the photographing optical system 30.

  According to the verification by the inventors, in macular photographing, smooth photographing was possible based on the in-focus position in the photographing optical system 30. On the other hand, in the nipple photography, the measurement light of the OCT optical system 200 is focused on the recessed portion, and as a result of lack of light from the part other than the nipple, a good tomographic image cannot be obtained and the photographing failure There was a case.

  Therefore, as one aspect of the present embodiment, the control unit 70 may perform control in consideration of the shift of the focus position due to the imaging region (see FIG. 6). In the present embodiment, for example, the control unit 70 may change the focus control for the fundus of the OCT optical system 200 according to the imaging region. Examples of the focus control include focus control based on an output signal from the imaging optical system 30, focus control based on an output signal from the OCT optical system 200, and focus control based on output signals from the imaging optical system 30 and the OCT optical system 200. , Etc. Hereinafter, an example of optimization control according to the present embodiment will be described in detail.

  When the reference mirror 131 and the focusing lens 124 are moved to the initial positions, the control unit 70 starts the first optical path length adjustment and the focus adjustment. Hereinafter, the control operation of each adjustment will be described.

<First automatic optical path length adjustment (coarse adjustment)>
The first automatic optical path length adjustment (automatic coarse optical path length adjustment) will be described. The control unit 70 controls the drive of the drive mechanism 150 to move the reference mirror 131 and acquires a fundus tomographic image based on output signals output from the detector 120 at each position of the reference mirror 131. The reference mirror 131 is moved to the position.

  Specifically, after acquiring the tomographic image at the initial position, the control unit 70 moves the reference mirror 131 toward the movement limit position opposite to the initial position. For example, when the limit position K1 is selected (set) as the initial position of the reference mirror 131, the reference mirror 131 is moved in the direction toward the limit position K2.

  Here, the control unit 70 moves the reference mirror 131 in predetermined steps (for example, a 2 mm step as an imaging range), sequentially acquires tomographic images at each moving position, and determines the position at which the fundus tomographic image is acquired. I will explore.

  In this case, the control unit 70 acquires a tomographic image every time the reference mirror 131 is stopped at the moving positions of the reference mirror 131 set discretely. Then, the control unit 70 analyzes the tomographic image acquired at each position. For example, the control unit 70 calculates the evaluation value B of the tomographic image acquired at each position. Then, the control unit 70 stores the position of the reference mirror 131 and the evaluation value B of the tomographic image in a memory in association with each other. As the evaluation value B, for example, B = ((average maximum luminance value of the image) − (average luminance value of the background area of the image)) / (standard deviation of the luminance value of the background area) may be obtained. .

  Here, the control unit 70 detects the peak of the evaluation value B from the obtained calculation result of the evaluation value B for each position of the reference mirror 131. Then, the control unit 70 stores the position of the reference mirror 131 corresponding to the peak detection position in the memory. Then, the control unit 70 moves the reference mirror 131 to a position corresponding to the peak of the evaluation value B.

  When the optical path length is adjusted roughly as described above, at least a part of the fundus tomographic image is displayed at any position on the display unit 75.

<First focus adjustment>
The control unit 70 may detect the in-focus position and move the lens 32 based on the detection result in parallel with the first automatic optical path length adjustment (automatic coarse optical path length adjustment). The control unit 70 may issue a trigger signal for starting control of focus adjustment and start focus adjustment of the photographing optical system 30.

<Second focus adjustment>
For example, when the macula is set as the imaging region, the control unit 70 moves the focusing lens 124 of the OCT optical system 200 based on the focus position information of the imaging optical system 30 based on the output signal from the image sensor 38. (Second focus adjustment). In this case, the control unit 70 may start the movement of the focusing lens 124 after the movement of the focusing lens 32 to the in-focus position is completed in the first focus control. Alternatively, the control unit 70 starts the movement of the focusing lens 124 with the timing at which the focusing position information of the photographing optical system 30 is detected before the movement of the focusing lens 32 to the focusing position is completed. May be.

  More specifically, the control unit 70 may acquire the focus position information of the OCT optical system 200 based on the focus position information of the imaging optical system 30 and move the focusing lens 124 to the focus position (OCT). Autofocus on the image). In this case, for example, the control unit 70 acquires the moving position of the focusing lens 32 as focusing position information of the OCT optical system 200, and drives and controls the driving mechanism 124a based on the focusing position information to control the focusing lens 124. It may be moved to the in-focus position.

  For example, if the focus position of the photographic optical system 30 is a position corresponding to −3D, the focus position of the OCT optical system 200 is similarly controlled to be a position corresponding to −3D. In this case, a correspondence may be made between the moving position of the focusing lens 32 and the moving position of the focusing lens 124. Thereby, the focus position of the OCT optical system 200 can be set to a focus position corresponding to the focus position of the imaging optical system 30.

  The control unit 70 may adjust the focus of the OCT optical system 200 using the focus detection result (for example, the separation amount of the index images S1 and S2) as the focus position information of the imaging optical system 30. . That is, a correspondence may be made between the focus detection result and the moving position of the focusing lens 124. For example, when the focus position of the imaging optical system 30 is a position corresponding to −3D, the focus position of the OCT optical system 200 may not be −3D, and a numerical value obtained by adding a correction value to −3D. A corresponding in-focus position may be used.

  In this way, the focusing lens 124 of the OCT optical system 200 is moved to the focus position based on the imaging optical system 30. After the movement is completed, the focus adjustment of the OCT optical system 200 with respect to the fundus oculi Ef is terminated.

<Third focus adjustment>
For example, when the nipple is set as the imaging part, the control unit 70 acquires the in-focus position information of the OCT optical system 200 based on the output signal from the detector 120 of the OCT optical system 200. The focusing lens 124 may be moved to the in-focus position (third focus adjustment).

  More specifically, the control unit 70 may move the focusing lens 124 to the in-focus position with respect to the fundus oculi Ef based on the output signal output from the detector 120 through the first automatic optical path length adjustment.

  The control unit 70 may control driving of the driving unit 124a and move the lens 124 in a predetermined step from the initial position. The control unit 70 may sequentially acquire tomographic images at the respective movement positions and search for an in-focus position (a position where the fundus tomographic image is in focus).

  For example, the control unit 70 may move the lens 124 by 0.5D toward a certain movement limit position, and may move the lens 124 in the opposite direction if the in-focus position is not found. In addition, the movement step of the lens 124 is not limited to this, For example, 1D may be sufficient, 2D may be sufficient, and the structure set arbitrarily may be sufficient.

  In the search for the in-focus position, every time the focusing lens 124 is stopped at the discretely set moving position of the focusing lens 124, an image acquired at that position may be analyzed. For example, the control unit 70 may calculate the evaluation value B of the tomographic image acquired at each position. The control unit 70 may store the position of the lens 124 and the evaluation value B of the tomographic image in a memory in association with each other. Of course, it is not limited to the evaluation value B, and a well-known technique can be used. For example, the technique described in JP2009-291252A may be used.

  The control unit 70 may detect the peak of the evaluation value B from the calculation result of the evaluation value B at each position of the focusing lens 124. The control unit 70 may move the focusing lens 124 to a position corresponding to the peak detection position. As described above, the focus adjustment is completed.

  Next, the control unit 70 controls the drive mechanism 124a to move the focusing lens 124 to a movement position corresponding to the in-focus position of the OCT optical system 200 acquired as described above. After the movement is completed, the focus adjustment of the OCT optical system 200 with respect to the fundus oculi Ef is terminated.

<Second automatic optical path length adjustment (fine adjustment)>
When the focusing lens 124 is moved to the in-focus position, the control unit 70 starts the second automatic optical path length adjustment. The controller 70 readjusts the position of the reference mirror 131 from the position adjusted by the first automatic optical path length adjustment based on the output signal output from the detector 120. The control unit 70 may adjust the position of the reference mirror 131 so that the tomographic image is positioned at a predetermined position.

<Polarizer adjustment>
The controller 70 may adjust the polarization state by driving the polarizer 133 based on the output signal output from the detector 120 after the second automatic optical path length adjustment. The control unit 70 may detect an evaluation value B (peak value) that becomes a peak based on the evaluation value B at each position of the polarizer 133. The control unit 70 may move the polarizer 133 to a position corresponding to the position where the peak value is detected. As described above, the polarizer adjustment is completed.

  As described above, by changing the focus control in accordance with the imaging region, the OCT optical system 200 can be smoothly focused on the fundus regardless of the imaging region.

  In the focus adjustment of the OCT optical system 200 in macular imaging, one aspect of using an output signal from the imaging optical system 30 is that, with the current focus detection technology, the imaging optical system performs focus detection in a shorter time. This is because it can be implemented.

  For example, the focus adjustment (second focus adjustment) of the OCT optical system 200 based on the separation information of the index images S1 and S2 is processed in comparison with the focus adjustment (third focus adjustment) of the OCT optical system 200 based on the evaluation of the tomographic image. Is early. Therefore, when the OCT focus can be appropriately performed using the index images S1 and S2, the focus of the imaging optical system 30 and the OCT optical system 200 may be adjusted using the separation information of the index images S1 and S2. .

  On the other hand, in the focus adjustment of the OCT optical system 200 in photographing the nipple, one aspect using an output signal from the OCT optical system 200 is avoidance of imaging defects.

  Even when the focus adjustment is performed using the output signal from the OCT optical system 200, the time required for the focus adjustment can be reduced by starting the focus adjustment before acquiring the focus result by the imaging optical system 30. Can be shortened.

  After the tomographic image is captured by the OCT optical system 200, the control unit 70 may control the imaging optical system 30 and capture a fundus front image based on an output signal from the image sensor 35. The acquired fundus front image may be stored in a memory. In this case, a front image and a tomographic image with good focus are acquired regardless of the imaging region by the focus control corresponding to the imaging region.

<Transformation example>
The controller 70 may use in-focus position information of the photographing optical system 30 in the third focus adjustment. For example, the focusing lens 124 may be moved to a position where an offset is added to the position corresponding to the in-focus position of the photographic optical system 30. For example, the offset amount may be set in consideration of the shift of the focus position due to the imaging region, and may be set by optical simulation, experiment, or the like.

  In this case, the control unit 70 may adjust the focus position based on the output signal from the OCT optical system 200 after the focusing lens moves to the position to which the offset is added. By adding an offset, the search time for the focus position can be shortened. That is, the control unit 70 may use the photographing optical system 30 and the OCT optical system 200 in combination in the third focus adjustment. In this case, the control unit 70 may change the range of the search area.

  In addition, the control unit 70 may stop the focusing lens 124 at a position where an offset is added to the position corresponding to the in-focus position of the photographing optical system 30. In this case, the focus control between the second focus adjustment and the third focus adjustment is different regarding whether or not an offset is applied.

  When the index images S1 and S2 cannot be detected, the control unit 70 may perform the third focus adjustment regardless of the imaging region. The control unit 70 may perform the focus adjustment of the photographing optical system 30 using the focus result in the third focus adjustment.

  Note that the method for detecting the in-focus state of the photographic optical system 30 is not limited to the above-described method, and a known technique can be used. For example, the accumulated luminance value of the entire fundus image may be used as the imaging state evaluation value, and the position where the accumulated luminance value shows a peak may be detected as the in-focus position, or the image data of the fundus image may be differentiated. The in-focus state may be detected based on the contour image at the time. The in-focus state may be detected based on the infrared fundus image before the differentiation process. In this case, the control unit 70 may determine that the focus of the imaging optical system 30 has failed when no peak is detected or when the evaluation value is low (eg, below a threshold value). As a detection method, for example, a method described in JP2009-291252A may be used.

  In the above configuration, the split target is used as the focus index, but the present invention is not limited to this, and a structure for detecting the in-focus state using an index (for example, a ring index or a point index) projected on the fundus Can be used for focus detection.

  In the above description, the first focus adjustment and the first optical path length adjustment are performed in parallel, but the present invention is not limited to this. For example, when several seconds (for example, 0.5 seconds) have passed since the first focus adjustment has been started, if the first focus adjustment is not completed, the first optical path length adjustment is performed in parallel, and the first focus is adjusted. If the adjustment is completed, the first optical path adjustment may be started.

DESCRIPTION OF SYMBOLS 1 Ophthalmic imaging device 30 Imaging optical system 32 Focusing lens 70 Control part 74 Operation part 75 Display part 90 Computer 95 Display part 120 Detector 124 Focusing lens 200 OCT optical system

Claims (4)

  1. A tomographic imaging optical system for imaging a tomographic image of the fundus of the eye to be examined;
    A front imaging optical system for imaging a front image of the fundus of the eye to be examined;
    Control means for performing focus control of the tomographic imaging optical system with respect to the fundus of the eye based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system;
    With
    The fundus imaging apparatus, wherein the control means changes an optical system used for the focus control according to a focus region on the fundus of the eye to be examined.
  2. The control means performs a first control for performing the focusing control based on an output signal from the tomographic imaging optical system, and a second control for performing the focusing control based on an output signal from the front imaging optical system. The fundus imaging apparatus according to claim 1 , wherein the control is changed according to a focused part on the fundus of the eye to be examined .
  3. The said control means changes the said focus control by the case where the focus site | part on a to-be-tested eye fundus is a macular part, and the case where it is a nipple part at least. Fundus imaging device.
  4. A fundus imaging program executed in the fundus imaging apparatus,
    The fundus imaging apparatus includes:
    A tomographic imaging optical system for imaging a tomographic image of the fundus of the eye to be examined;
    A front imaging optical system for imaging a front image of the fundus of the eye to be examined,
    By being executed by the processor of the fundus imaging device,
    A control step for performing focusing control of the tomographic imaging optical system with respect to the fundus of the eye to be examined based on an output signal from at least one of the tomographic imaging optical system and the front imaging optical system; A control step of changing the optical system used for the focus control according to the focus part,
    A fundus imaging program executed by the fundus imaging apparatus.
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