JP6040562B2 - Attachment for fundus photography device - Google Patents

Description

About eye bottom imaging device for attachment to a tomographic image of the eye fundus.

  The light beam emitted from the light source is divided into a measurement light beam and a reference light beam. There is known a fundus photographing apparatus (Optical Coherence Tomography: OCT) which has an interference optical system in which interference light obtained by combining with a light beam is received by a light receiving element and photographs a tomographic image of the fundus of the eye to be examined. In such an apparatus, by moving a predetermined optical path length changing member in the optical axis direction, the optical path difference between the measurement light and the reference light can be adjusted in accordance with the difference in the axial length of the eye to be examined. (See Patent Document 1).

  In the conventional OCT, an apparatus is designed with a human eye as an object to be imaged. That is, the OCT measurement optical path is assumed to be an optical path length including the length of the eye axis length of the human eye, and the optical path length of the reference optical path is set to correspond to the measurement optical path.

JP 2008-29467 A

  By the way, there is a demand for taking a tomographic image of an animal eye as an object to be imaged by the OCT. However, the axial length of human eyes and animal eyes differ greatly. For example, the eyes of animals such as rats and rabbits have a shorter axial length than human eyes. For this reason, the optical path length of the measurement optical path is shorter than the optical path length of the reference optical path, and an interference signal cannot be obtained. Conventionally, the image was taken by moving the animal eye away from the device. However, the conjugate position with the optical scanner deviates from the pupil position of the animal eye, resulting in vignetting of the measurement light beam and narrowing the shooting angle of view. Problems arise. A similar problem may occur when taking a tomographic image of a human eye such as an infant.

In view of the above problems, and an object to provide an ocular bottom for the photographing apparatus A Attachment to the axial length can easily acquire the fundus tomographic image of a short eye.

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

(1) An attachment for a fundus photographing apparatus according to the first aspect of the present disclosure includes an optical scanner that deflects the measurement light to scan the measurement light emitted from the light source on the fundus, and between the eye to be examined and the optical scanner. An objective lens system disposed in the optical system, wherein the objective lens system optically arranges the optical scanner and a pupil center of the eye to be examined at a conjugate position, and transmits measurement light through the pupil center to the eye fundus to be examined. The measurement optical system that has a measurement optical system that guides the reflected light and obtains the reflected light, and a reference optical system that causes the reference light emitted from the light source to interfere with the measurement light, and is reflected by the fundus of the test object An interference optical system for receiving an interference signal light generated by interference between the measurement light from the measurement light from the reference light and the reference light from the reference optical system and the reference light, and the measurement optical system or the reference optical system Located in the optical path, the optical path between the measurement light and the reference light An optical member for varying the optical path length that is moved in the optical axis direction by the drive unit to adjust the length difference, and is mounted on a fundus photographing apparatus that obtains a fundus tomographic image based on a signal output from the photodetector An attachment for a possible fundus imaging apparatus , comprising a convex lens, and a concave lens disposed between the objective lens system and the convex lens, and is attachable to the fundus imaging apparatus, so that the measurement optics The optical path length of the measurement optical path is extended with respect to the optical path length variable range that is disposed in the optical path of the system and driven by the optical member for changing the optical path length, and the fundus of the eye having a short axial length is photographed .

  According to the present invention, it is possible to easily acquire a fundus tomographic image of an eye having a short eye axis length.

  Embodiments according to the present invention will be described below with reference to the drawings. 1 to 5 are diagrams illustrating the configuration of the fundus imaging apparatus according to the present embodiment. 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.

<Overview>
An outline of a fundus imaging apparatus according to an embodiment of the present invention will be described. A fundus imaging apparatus (optical coherence tomography device) 1 according to the present embodiment includes an interference optical system 200 and an optical member for changing an optical path length (for example, a reference mirror 31), and obtains a fundus tomographic image.

  The interference optical system (OCT optical system) 200 includes an optical scanner (scanning unit) 23, a measurement optical system 200a, and a reference optical system 200b. The interference optical system 200 receives the interference signal light generated by the interference between the measurement light from the measurement optical system 200a reflected from the fundus of the test object and the reference light from the reference optical system 200b by the photodetector 83.

  The optical scanner 23 deflects the measurement light to scan the measurement light emitted from the light source on the fundus. The measurement optical system 200 a includes a first objective lens system (for example, the objective lens 10) disposed between the eye to be examined and the optical scanner 23. The measurement optical system 200a optically arranges the optical scanner 23 and the pupil center of the eye to be examined at the conjugate position by the objective lens system, and guides the measurement light to the fundus of the eye to be examined through the pupil center to obtain the reflected light. Is provided. The reference optical system 200b is provided to cause the reference light emitted from the light source to travel in the apparatus and interfere with the measurement light.

  The fundus imaging apparatus further includes an optical path length extension unit 500 that extends the optical path length of the measurement optical path with respect to the optical path length variable range by driving the optical member for changing the optical path length. The optical path length extension unit 500 is disposed in the optical path of the measurement optical system 200a. The optical path length extension unit 500 makes it possible to adjust the optical path length of the measurement light that exceeds the movable range of the optical member for changing the optical path length. The optical path length extension unit 500 is provided as a separate member different from the optical member for changing the optical path length.

  The optical path length extension unit 500 is detachably disposed in the optical path of the measurement optical system 200a, for example. For example, the optical path length extension unit 500 may be an attachment (adapter) that can be mounted in the vicinity of the examination window 160 of the fundus imaging apparatus. Such an attachment is designed, for example, for photographing an animal eye having an axial length shorter than that of the human eye as the subject eye to be photographed. The optical path length extension unit 500 may be disposed inside the apparatus main body 100.

  The optical path length extension unit 500 includes a concave lens 511 and a convex lens 512, and the concave lens 511 and the convex lens 512 are arranged so that their optical axes substantially coincide with each other. For example, the concave lens 511 is disposed between the convex lens 512 and the first objective lens system, and substantially matches the conjugate point of the optical scanner 23 by the first objective lens system with the focal position of the concave lens.

  The optical path length extension unit 500 may have a drive unit that drives an optical member provided in the optical path length extension unit in order to vary the optical path length of the measurement light beam. For example, the optical path length extension unit 500 may have a drive unit that drives at least one of the concave lens 511 and the convex lens 512 in order to vary the optical path length of the measurement light beam.

  The optical path length extension unit 500 is, for example, disposed between the second objective lens system disposed in front of the eye of the subject's eye and the first objective lens system and the second objective lens system, and the optical path length of the measurement optical path. And an optical member for delaying. As an optical member for delaying light, a configuration in which the measurement light is delayed by a combination of a glass plate, a plurality of mirrors, etc. in addition to the concave lens can be considered.

  In the following description, the objective lens 10 forms a first objective lens system. However, the first objective lens system may be composed of at least one lens, and an objective lens composed of a plurality of lenses. It may be a system.

  In this embodiment, the optical path length extension unit 500 is used when photographing an animal eye (for example, rat, rabbit, etc.) having an axial length different from that of the human eye. The OCT optical system 200 is based on, for example, an SD-OCT optical system and an SS-OCT optical system. In this case, the OCT optical system 200 detects, by the detector 83, spectral information of light obtained by combining the measurement light reflected from the eye fundus of the eye to be examined and the reference light as an interference state between the measurement light and the reference light. The control unit 70 captures a tomographic image of the fundus of the eye to be examined by performing Fourier analysis on the spectrum information (spectrum signal) detected by the detector 83. The memory 72 stores an animal eye photographing mode and a human eye photographing mode, and the optical path length extension unit 500 is inserted and removed according to the mode switching.

  In the present embodiment, in the measurement optical path between the concave lens 511 and the convex lens 512, the principal ray of the measurement light is arranged so as to be a substantially parallel light beam with respect to the optical axis. As a result, the measurement optical path can be extended in a state where the proper working distance between the attachment and the anterior eye portion to be examined is maintained substantially constant.

  As described above, since the optical path length of the measurement light can be extended by arranging the optical path length extension unit 500, the measurement optical system can be used even for an eye to be examined whose eye axis length is short. 200a, the reference optical system 200b, and the length of the optical path length can be substantially matched.

  In addition, you may provide the structure which can move the optical member in the adapter 501. FIG. For example, the adapter 501 may include a driving unit that drives at least one of the concave lens 511 and the convex lens 512 in order to extend the optical path length of the measurement light and to further change the optical path length of the measurement light beam. Thereby, after adjusting the optical path length of the measurement optical path by the arrangement of the second optical path length extension unit 500, the optical path length can be further adjusted.

  In the above description, the configuration in which the optical path length is adjusted according to the shooting position by moving the reference mirror 31 is exemplified, but the present invention is not limited to this. The apparatus of this embodiment should just be the structure provided with the drive part which moves the optical member arrange | positioned in the optical path of measurement light or reference light in order to adjust the optical path length difference of measurement light and reference light. For example, as a configuration for changing the optical path length between the optical path length of the measurement light and the optical path length of the reference light, the optical path length difference from the reference light is adjusted by changing the optical path length of the measurement light. Also good. For example, in the optical system shown in FIG. 1, the reference mirror 31 is fixed, and the collimator lens 21 and the fiber end 39b are moved integrally to change the optical path length of the measurement light with respect to the optical path length of the reference light. Can be considered.

<Example>
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an optical system and a control system of the ophthalmologic photographing apparatus according to the present embodiment. In the present embodiment, the depth direction of the eye to be examined is described as the Z direction (optical axis L1 direction), the horizontal direction component on the plane perpendicular to the depth direction is defined as the X direction, and the vertical direction component is defined as the Y direction.

  This apparatus is an optical coherence tomography device (OCT device) 1. In FIG. 1, the OCT device 1 includes an interference optical system (OCT optical system) 200, a fixation target projection unit 300, and a control unit (CPU) 70.

  The OCT optical system 200 divides the light beam emitted from the measurement light source into measurement light and reference light, guides the measurement light beam to the fundus of the eye to be examined, guides the reference light to the reference optical system, and then reflects the measurement light reflected on the fundus The spectrum (interference state) of the light combined with the reference light is detected by a detector (light receiving element).

  The OCT optical system 200 includes a measurement optical system 200a and a reference optical system 200b. In addition, the interference optical system 200 splits the interference light generated by the reference light and the measurement light for each frequency (wavelength) and causes the light receiving means (in this embodiment, a one-dimensional light receiving element) to receive the split interference light. An optical system 800 is included. Further, the dichroic mirror 40 has a characteristic of reflecting light having a wavelength component used as measurement light of the OCT optical system 200 and transmitting light having a wavelength component used for the fixation target projection unit 300.

  First, the configuration of the OCT optical system 200 provided on the reflection side of the dichroic mirror 40 will be described. The OCT light source 27 is a light source that emits low-coherent light used as measurement light and reference light of the OCT optical system 200. For example, an SLD light source or the like is used. For the OCT light source 27, for example, a light source having a center wavelength of 840 nm and a bandwidth of 50 nm is used. The fiber coupler 26 serves both as a light splitting member and a light coupling member. The light emitted from the OCT light source 27 is split into reference light and measurement light by the fiber coupler 26 via an optical fiber 38a as a light guide. The measurement light goes to the eye E through the optical fiber 38b, and the reference light goes to the reference mirror 31 through the optical fiber 38c (polarizer (polarizing element) 33).

  In the optical path for emitting the measurement light toward the eye E, the end 39b of the optical fiber 38b for emitting the measurement light, the collimator lens 21, the focusing optical member (focusing lens) 24, the scanning unit (optical scanner) 23, and A relay lens 22 is arranged. The scanning unit 23 is configured by two galvanometer mirrors, and is used to cause the measurement light emitted from the measurement light source to scan two-dimensionally (XY direction) on the fundus by driving the scanning drive mechanism 51. Note that the scanning unit 23 may be configured by, for example, an AOM (acousto-optic element), a resonant scanner, or the like.

  The dichroic mirror 40 and the objective lens 10 serve as a light guide optical system that guides OCT measurement light from the OCT optical system 200 to the fundus of the eye to be examined.

  The focusing lens 24 is movable in the optical axis direction by driving of the driving mechanism 24a, and is used for correcting the diopter for the subject's fundus.

  The measurement light emitted from the end 39b of the optical fiber 38b is collimated by the collimator lens 21, and then reaches the scanning unit 23 via the focusing lens 24, and the reflection direction is changed by driving the two galvanometer mirrors. Then, the measurement light reflected by the scanning unit 23 is reflected by the dichroic mirror 40 via the relay lens 22 and then condensed on the fundus of the eye to be examined via the objective lens 10.

  Then, the measurement light reflected from the fundus is reflected by the dichroic mirror 40 via the objective lens 10, travels toward the OCT optical system 200, relay lens 22, two galvanometer mirrors of the scanning unit 23, focusing lens 24, and collimator lens. 21 enters the end 39b of the optical fiber 38b. The measurement light incident on the end 39b reaches the end 84a of the optical fiber 38d through the optical fiber 38b, the fiber coupler 26, and the optical fiber 38d.

  The reference optical system 200b generates reference light that is combined with reflected light acquired by reflection of measurement light at the fundus oculi Ef. The reference optical system 200b may be a Michelson type or a Mach-Zehnder type. The reference optical system 200 b is formed by, for example, a reflection optical system (for example, the reference mirror 31), and reflects light from the coupler 26 back to the coupler 26 by the reflection optical system, and guides it to the light receiving element 83. As another example, the reference optical system 200b is formed by a transmission optical system (for example, an optical fiber), and guides the light from the coupler 26 to the detector 83 by transmitting the light without returning.

  For example, the optical fiber 38 c, the end 39 c of the optical fiber 38 c that emits the reference light, the collimator lens 29, and the reference mirror 31 are arranged in the optical path that emits the reference light toward the reference mirror 31. The optical fiber 38c is rotated by the drive mechanism 34 in order to change the polarization direction of the reference light. That is, the optical fiber 38c and the drive mechanism 34 are used as a polarizer 33 for adjusting the polarization direction. The polarizer is not limited to the above-described configuration, and any polarizer may be used as long as the polarization state of the measurement light and the reference light is substantially matched by driving the polarizer disposed in the optical path of the measurement light or the optical path of the reference light. . For example, a half-wave plate or a quarter-wave plate can be used, or one that changes the polarization state by applying pressure to the fiber to deform it can be applied.

  The polarizer 33 (polarization controller) may be configured to adjust the polarization direction of at least one of the measurement light and the reference light in order to match the polarization directions of the measurement light and the reference light. For example, the polarizer may be arranged in the optical path of the measurement light.

  Further, the reference mirror driving mechanism 50 generates reference light that is combined with reflected light acquired by reflection of measurement light on the fundus oculi Ef.

  The reference light emitted from the end 39c of the optical fiber 38c is converted into a parallel light beam by the collimator lens 29, reflected by the reference mirror 31, collected by the collimator lens 29, and incident on the end 39c of the optical fiber 38c. The reference light incident on the end 39c reaches the fiber coupler 26 via the optical fiber 38c and the optical fiber 38c (polarizer 33).

  Then, the reference light generated as described above by the light emitted from the light source 27 and the fundus reflection light by the measurement light irradiated on the eye fundus to be examined are combined by the fiber coupler 26 to be interference light, The light is emitted from the end portion 84a through the fiber 38d. A spectroscopic optical system 800 (spectrometer unit) that separates interference light into frequency components to obtain an interference signal for each frequency includes a collimator lens 80, a grating mirror (diffraction grating) 81, a condensing lens 82, and a light receiving element 83. . The light receiving element 83 is a one-dimensional element (line sensor) having sensitivity in the infrared region.

  Here, the interference light emitted from the end portion 84 a is collimated by the collimator lens 80, and then is split into frequency components by the grating mirror 81. Then, the interference light split into frequency components is condensed on the light receiving surface of the light receiving element 83 via the condenser lens 82. Thereby, spectrum information (spectrum signal) of interference fringes is recorded on the light receiving element 83. Then, based on the output signal from the light receiving element 83, analysis is performed using Fourier transform to capture a tomographic image of the eye (fundus tomographic image). That is, the spectrum information is input to the control unit 70 and analyzed using Fourier transform, whereby information in the depth direction of the eye to be examined can be measured. Here, the control unit 70 can acquire a tomographic image by causing the scanning unit 23 to scan the measurement light on the fundus in a predetermined transverse direction. For example, by scanning in the X direction or the Y direction, a tomographic image (fundus tomographic image) on the XZ plane or YZ plane of the subject's fundus can be acquired (in this embodiment, the measurement light is applied to the fundus in this way. On the other hand, a method of performing one-dimensional scanning and obtaining a tomographic image is referred to as B-scan). The acquired fundus tomographic image is stored in the memory 72 connected to the control unit 70. Furthermore, by controlling the driving of the scanning unit 23 and scanning the measurement light in the XY direction two-dimensionally, based on the output signal from the light receiving element 83, the two-dimensional moving image regarding the XY direction of the subject's eye fundus A three-dimensional image of the fundus of the eye to be examined can be acquired.

  The focusing lens 24 is moved in the optical axis direction by driving of the drive mechanism 24a, and its movable range is set. For example, the focusing lens 24 is movable in a range from a position where the refractive power corresponds to −12D (a position where the focus is achieved by the refractive power of −12D) to a position where the first refractive power corresponds to + 12D.

  Next, the fixation target projection unit 300 will be described. The fixation target projecting unit 300 includes an optical system for guiding the line-of-sight direction of the eye E. The fixation target projection unit 300 has a fixation target to be presented to the eye E, and can guide the eye E in a plurality of directions.

  For example, the fixation target projection unit 300 has a visible light source that emits visible light, and changes the presentation position of the target two-dimensionally. Thereby, the line-of-sight direction is changed, and as a result, the imaging region is changed. For example, when the fixation target is presented from the same direction as the imaging optical axis, the center of the fundus is set as the imaging site. When the fixation target is presented upward with respect to the imaging optical axis, the upper part of the fundus is set as the imaging region. That is, the imaging region is changed according to the position of the target with respect to the imaging optical axis.

  As the fixation target projection unit 300, for example, a configuration in which the fixation position is adjusted by the lighting positions of LEDs arranged in a matrix, light from a light source is scanned using an optical scanner, and fixation is performed by lighting control of the light source. Various configurations such as a configuration for adjusting the position are conceivable. The projection unit 300 may be an internal fixation lamp type or an external fixation lamp type.

  The control unit 70 is connected to a display monitor 75, a memory 72, a control unit 74, a reference mirror driving mechanism 50, a focusing lens driving mechanism 24a, a driving mechanism 34 for an optical fiber 38c, and the like.

<Optical path length extension unit>
FIG. 2 is a diagram for explaining attachment / detachment of the adapter 501 (attachment) as the optical path length extension unit 500. FIG. 2A is a diagram showing a state where no adapter is attached to the inspection window 160. FIG. 2B is a view showing a state where the adapter 501 is attached to the inspection window 160. The adapter 501 is attached to the examination window 160 when an animal eye (for example, rat, rabbit, etc.) is photographed as the eye to be examined. The adapter 501 has a lens system that extends the optical path length of the measurement light with respect to the eye to be examined. Thereby, since the optical path length of measurement light can be extended, it becomes possible to match | combine the length of optical path length with the measurement optical system 200a, the reference optical system 200b. In other words, even for an eye to be examined having a short ocular axial length, the optical path length difference between the measurement optical path and the reference optical path can be adjusted by driving the reference mirror 31 of the reference optical system 200b.

  The inspection window 160 is provided with a groove 162, and a convex portion (not shown) of the adapter 501 and the groove 162 are fitted together, and the rotation of the adapter 501 is restricted. The examiner pinches the chuck portions 520 provided on the left and right sides, and attaches the adapter 501 so that the convex portion 522 provided at the tip of the chuck portion 520 fits into the concave portion 165 of the inspection window 160 (see FIG. 3). As a mechanism for attaching the adapter 501, various modifications such as a mechanism using a screw and a mechanism using a magnet can be considered. In the present embodiment, the mechanism as shown in FIG. 3 is used so that the adapter 501 can be attached and detached smoothly.

FIG. 4 is an optical side view for explaining the internal configuration of the adapter 501. FIG. 4 (a)
It is a figure before adapter mounting. In FIG. 4A, the human eye Eh is taken as the subject to be imaged. FIG. 4B is a diagram after the adapter is mounted. In FIG. 4 (a), an animal eye Ea is taken as a subject to be imaged as the eye to be examined. As shown in FIG. 4B, the adapter 501 has a lens system 510 for extending the optical path length of the measurement light. The lens system 510 is a lens system having a focal length corresponding to an appropriate working distance WD between the adapter 501 and the anterior eye portion to be examined, and a principal ray of measurement light between the concave lens 511 and the convex lens 512. And the optical axis L1 are parallel to each other. The lens system 510 includes a concave lens 511 and a convex lens 512.

  As shown in FIG. 4B, the measurement light emitted from the light source 27 travels to the lens optical system 510 in the adapter 501 through the objective lens 10. The measurement light is converted into a parallel light beam by the concave lens 511 and is incident on the convex lens 512. The parallel light beam incident on the convex lens is condensed on the fundus of the eye to be examined by the convex lens. At this time, since the measurement light passing between the concave lens 511 and the convex lens 512 is a parallel light beam, the optical path length of the distance D between the concave lens 511 and the convex lens 512 is extended. That is, by extending the optical path length of the measurement light, the optical path length of the reference light and the optical path length of the measurement light match, so that interference light can be acquired.

  The adapter 501 is configured according to the animal to be photographed. For example, a rabbit-specific adapter and a rat-specific adapter are provided, and a dedicated adapter suitable for the animal at the time of shooting is attached to perform shooting. For example, in these adapters, the arrangement position of the lens system in the adapter is set based on the average axial length of each animal. When photographing an animal with a short eye axis length, the convex lens and the concave lens are arranged so that the distance between the convex lens and the concave lens is long. Further, when photographing an animal having a long eye axis length, the convex lens and the concave lens are arranged so that the distance between the convex lens and the concave lens is shortened.

  As described above, by providing the adapter 501 that extends the optical path length of the measurement light, even when the subject eye to be photographed is an animal eye with a short axial axis length, the optical path length adjustment can be performed with little influence on the WD. It can be performed. Thus, even if the subject to be photographed is an animal eye, photographing can be performed easily.

<Control action>
The control operation of the apparatus having the above configuration will be described. When photographing an animal eye as the eye to be examined, the examiner attaches the adapter 501 to the examination window 160. The examiner, after fixing the animal to the apparatus, looks at the monitor 75 with the anterior ocular segment observation image taken with the anterior ocular segment observation camera (not shown) so that the measurement optical axis is at the center of the pupil of the eye to be examined. An alignment operation is performed using a joystick (not shown).

  Next, optimization is performed so that the fundus site desired by the examiner can be observed with high sensitivity and high resolution. In the present embodiment, the optimization control is control of optical path length adjustment, focus adjustment, and polarization state adjustment (polarizer adjustment). For example, the control unit 70 adjusts the optical path length by moving the reference mirror 31. Further, the control unit 70 adjusts the focus state by moving the focusing lens 24.

  Then, the control unit 70 controls driving of the scanning unit 23, scans the measurement light on the fundus, acquires a light reception signal corresponding to the scanning region from an output signal output from the light receiving element 83 during the scanning, and obtains the fundus oculi. Form an image.

  Here, an example of a method for acquiring a fundus tomographic image (hereinafter referred to as a tomographic image) and a fundus frontal image (hereinafter referred to as a front image) according to the present embodiment will be described. The control unit 70 processes the spectral data detected by the light receiving element 83 and forms a tomographic image and a front image by image processing. The tomographic image and the front image may be acquired at the same time, may be acquired alternately, or may be acquired sequentially. That is, the spectrum data is used for obtaining at least one of a tomographic image and a front image. The acquired tomographic image and fundus image are displayed on the monitor 75 as a moving image or a still image. Here, when an imaging switch (not shown) is pressed by the examiner, a fundus tomographic image and a fundus front image are captured and stored in the memory 75.

<Transformation example>
In the present embodiment, the lens system 510 installed in the adapter 501 may be configured to be movable in the apparatus optical axis direction. For example, the convex lens 512 may be movable. In this case, by moving the convex lens 512, the distance D through which the measurement light between the convex lens 512 and the concave lens 511 passes as a parallel light beam is changed. Accordingly, the distance D of the parallel light flux is changed in a state where the WD between the eye to be examined and the convex lens 512 is substantially maintained, so that the optical path length is changed. For example, FIG. 5 is a diagram for explaining a change in optical path length when the convex lens 512 is driven. FIG. 5A shows the optical path of the measurement light before the convex lens 512 is driven. FIG. 5B shows the optical path of the measurement light when the convex lens 512 is moved in the direction of the eye E. By moving the convex lens 512 in the direction of the eye to be inspected, the distance D of the parallel light flux is extended while the WD is substantially maintained, so that the optical path length of the measurement light is extended. FIG. 5C shows the optical path of the measurement light when the convex lens 512 is moved in the direction of the objective lens 10. When the convex lens 512 is moved in the direction of the eye to be examined, the distance D of the parallel light flux is shortened while the WD is substantially maintained, so that the optical path length of the measurement light is shortened. Therefore, the optical path length adjustment can be performed not only by adjusting the reference mirror 31 provided in the OCT device 1 but also by driving the convex lens 512. Further, by moving the lens system 510 in the adapter in this way, the optical path length can be adjusted by moving the lens system without providing a plurality of adapters dedicated to each animal. For this reason, various animal eyes Ea1, Ea2, and Ea3 can be photographed with one adapter.

  The concave lens 511 may be movable. In this case, since the incident position of the measurement light beam on the convex lens changes, the angle at which the measurement light beam is refracted when passing through the convex lens changes depending on the incident position. As a result, the shooting angle of view changes. That is, by moving the concave lens 511, the shooting angle of view can be changed. At this time, since the concave lens 511 moves between the objective lens 10 and the convex lens 512, the length of the optical path length hardly changes.

  When the concave lens is moved, the length of the optical path length hardly changes, but may be used for adjusting the optical path length in the same manner as when the convex lens is moved. However, when adjusting the optical path length by moving the lens system 510 in the adapter, it is possible to change the optical path length more greatly when the convex lens 512 is moved than when the concave lens 511 is moved. Because there is, it is more preferable.

  When driving the lens system 510 in the adapter 501, a configuration for detecting the position of the lens system 510 may be provided. For example, when the positions of the convex lens 512 and the concave lens 511 are detected, the movement amount of each lens is calculated based on the position of each lens. Then, based on the moving amount of each lens, the diopter and the photographing range are calculated and displayed on the monitor 75. This makes it possible to observe imaging conditions and animal eye conditions. In addition, as a structure which detects a lens position, it can carry out by the encoder etc. which are provided in the drive mechanism not shown for driving the lens system 510, for example.

  In this embodiment, a diopter correction lens (for example, a convex lens 512 or a concave lens 511) having a predetermined refractive power may be used. Animal eyes have different refractive characteristics than human eyes. For this reason, in the conventional focus adjustment range (focus adjustment range when a human eye is a target), focus adjustment may not be performed appropriately. At this time, it is possible to change the focus adjustment range by using the convex lens 512 and the concave lens 511 having a predetermined refractive power. For example, when the animal eye to be photographed is a hyperopic eye, focus adjustment is performed in the D (diopter) adjustment range where the refractive power is + (plus). In this case, for example, the lens system 510 in the adapter 501 is configured to have a refractive power of + 5D, and the adjustment range of −12D to + 12D is changed to the adjustment range of −7D to + 17D. As a result, focus adjustment can be performed even for a hyperopic animal eye.

  In this embodiment, a convex lens 512 and a concave lens 511 are used as the lens system 510 for changing the optical path length. However, the present invention is not limited to this. Various combinations of lenses are conceivable for the lenses constituting the lens system 510. For example, an adapter constituted by a plurality of convex lenses and an adapter constituted by a plurality of glass plates can be mentioned. In these cases, since the WD becomes short, it may be difficult for the examiner to perform operations such as adjusting the position of the animal eye.

  For example, in the case where a plurality of glass plates are arranged, in order to extend the optical path length, since many glass plates are provided, the adapter becomes large, and the WD between the adapter and the eye to be examined becomes small. Moreover, when using a glass plate, since the optical path length can be extended only about half of the thickness of the installed glass plate, the number of glass plates will increase. For this reason, the WD becomes too short, and the glass plate may not be able to extend the desired optical path length or may be costly.

  In addition, when a plurality of convex lenses are used, the measurement light is more easily collected than a combination of a concave lens and a convex lens. Therefore, it is necessary to bring the eye to be examined closer to the adapter in order to perform appropriate imaging. . For this reason, WD becomes small.

  In the present embodiment, a configuration for detecting attachment / detachment of the adapter may be provided. By detecting the attachment / detachment of the adapter, it is possible to appropriately check the mounting state of the adapter, and it is possible to perform shooting in an appropriate mounting state. For example, as a method for detecting attachment / detachment of an adapter, a light reflecting member is provided in the adapter. In addition, a light source and a light receiving element for adapter detection are provided in the OCT device. Then, the light emitted from the adapter detection light source is reflected by the light reflecting member in the adapter, and the attachment / detachment of the adapter is detected by detecting the reflected light by the light receiving element (for details, refer to JP 2011-147609 A). See the official gazette).

  In this embodiment, an optical member (for example, a glass plate) that can be inserted into and removed from the measurement optical path of the OCT device 1 may be provided, and the length of the optical path length may be adjusted by inserting and removing the optical member. Moreover, it is good also as a structure which can provide the optical member which can be inserted or removed in an adapter, and can adjust the length of an optical path length. Of course, it is good also as a structure which can replace the optical member in an adapter.

  Further, it may have a human eye photographing mode and an animal eye photographing mode, and an optical member for adjusting the length of the measurement optical path may be inserted / removed based on the mode switching signal.

<Reference example>
In the above embodiment, the optical path length extension unit 500 is used to cope with an eye that is shorter than usual. However, other methods are possible. For example, the drive range of the optical member for changing the optical path length such as the reference mirror 31 may be configured to be widely set so as to correspond to eyes shorter than normal, such as animal eyes, in addition to normal human eyes.

  In this case, a mode switching unit that switches between a first shooting mode corresponding to a normal human eye (for example, a range of 17 mm to 32 mm) and a second shooting mode corresponding to a shorter eye (for example, a range of 3 mm to 17 mm). Is provided.

  The control unit 70 changes a search range (movement range of the optical member for changing optical path length) when moving the optical member for changing optical path length so as to obtain a fundus tomographic image according to each imaging mode. Also good. For example, in the first imaging mode, the optical member for changing the optical path length is driven in a range corresponding to a normal human eye, and a position where a fundus tomographic image is acquired is searched. On the other hand, in the second imaging mode, the optical member for changing the optical path length is driven in a range corresponding to an eye shorter than usual, and a position where a fundus tomographic image is acquired is searched.

  When searching for a position where a fundus tomographic image is obtained, the control unit 70 moves the optical member for changing the optical path length in a predetermined step, for example, and searches for a position where the fundus tomographic image is acquired. Then, the control unit 70 determines whether or not a fundus tomographic image is acquired based on a signal from the light receiving element 73, and based on the determination result, the optical member for varying the optical path length is located at a position where the fundus tomographic image is acquired. (For details, refer to Japanese Patent Application No. 2011-080430).

It is a figure which shows the optical system and control system of the ophthalmologic imaging device which concerns on a present Example. It is a figure explaining attachment and detachment of an adapter. It is sectional drawing when an adapter is mounted | worn with the test | inspection window. It is an optical side view explaining the internal structure of an adapter. It is a figure explaining the optical path length change at the time of the drive of the convex lens 512. FIG.

DESCRIPTION OF SYMBOLS 10 Objective lens 23 Scanning part 24 Focusing lens 24a Drive mechanism 31 Reference mirror 33 Polarizer 34 Drive mechanism 50 Drive mechanism 70 Control part 72 Memory 75 Display monitor 160 Inspection window 200 OCT optical system 300 Fixation target projection unit 501 Adapter 511 Convex lens 512 Convex lens

Claims (1)

An optical scanner for deflecting the measurement light to scan the fundus of the measurement light emitted from the light source, and an objective lens system disposed between the eye to be examined and the optical scanner, and the objective lens system A measurement optical system that optically arranges the optical scanner and the pupil center of the eye to be examined at a conjugate position, and guides the measurement light to the fundus of the eye to be examined through the pupil center,
A reference optical system for causing the reference light emitted from the light source to interfere with the measurement light,
Interference optics for receiving, by a photodetector, interference signal light generated by interference between the measurement light from the measurement optical system reflected by the fundus of the test object and the reference light from the reference optical system and the reference light. The system,
An optical member for varying the optical path length that is disposed in the optical path of the measurement optical system or the reference optical system and is moved in the optical axis direction by a drive unit to adjust the optical path length difference between the measurement light and the reference light. ,
An attachment for a fundus imaging apparatus that can be attached to a fundus imaging apparatus that obtains a fundus tomographic image based on a signal output from the photodetector ,
A convex lens, and a concave lens disposed between the objective lens system and the convex lens, and can be mounted on a fundus photographing apparatus so that the optical lens can be varied in the optical path of the measurement optical system. An attachment for a fundus photographing apparatus characterized in that an optical path length of a measurement optical path is extended with respect to an optical path length variable range by driving an optical member and a fundus of an eye having a short axial length is photographed .

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