JP2020000932A - Ocular fundus photographing device - Google Patents

Abstract

To provide a novel technology on an ocular fundus photographing device using a split detection method.SOLUTION: An ocular fundus photographing device includes a light source, an optical scanner, an optical fiber, a light guide system, a light detection part, and an image formation part. The optical scanner scans the ocular fundus of an eye to be examined with the light from the light source. The optical fiber has a plurality of optical waveguides. The light guide system guides return light from the ocular fundus to an incident end of the optical fiber. The light detection part detects the lights emitted from at least three regions at an emission end of the optical fiber respectively. The image formation part forms a first image based on the result of detection of the light emitted from a first region of the at least three regions, and forms a second image based on the result of detection of the light emitted from two or more regions other than the first region of the at least three regions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fundus photographing apparatus.

  A contour-enhanced image can be acquired by a scanning microscope using the Split Detection method (for example, Non-Patent Document 1). In recent years, research for applying this technique to a scanning laser ophthalmoscope (hereinafter, referred to as SLO) to observe the morphology of the fundus in more detail has been advanced (for example, Non-Patent Documents 2 to 3). Reference 4).

  In the Split Detection method, a peripheral light beam at the center of the point image at the fundus conjugate point is used. By dividing this peripheral light beam into a plurality of light beams and performing arithmetic processing using the plurality of divided light beams, a phase contrast image in a frequency band different from the fundus conjugate point image can be obtained. Such a split detection technique is expected as a technique that enables observation of a fundus tissue (particularly, a photoreceptor inner segment) that has not been successfully visualized in vivo so far.

T. Wilson and D.S. K. Hamilton, "Differential Amplitude Contrast Imaging in the Scanning Optical Microscope", Applied Physics B. 1983, p. 187-191 Yusufu N. et al. Sulai, Drew Scales, Zachary Harvey, and Alfredo Dubra, "Visualization of recreational vasculature and promotion of non-conformance without consultation. Opt. Soc. Am. A 2014 pp. 569-579 Drew Scales, Yufufu N. Sulai, Christopher S. Langlo, Gerald A .; Fishman, Christine A. Curcio, Joseph Carroll, and Alfredo Dubra, "In Vivo Imaging of Human Cone Photoreceptor Inner Segments", IOVS. 14-14542 pp. 4244-4251 Ethan A. Rossi, Kenichi Saito, Charles E. Granger, Koji Nozato, Qiang Yang, Tomaki Kawakami, Jie Zhang, William Fischer, David R. Williams, and Mina M. Chung, "Adaptive Optics Imaging of Putative Cone Inner Segments With With Geographic Atrophy Legions", ARVO 2015.

  In the conventional configuration, first, a light beam splitting element (such as an annular mirror that is annularly opened) arranged at the conjugate point of the fundus divides the light beam at the central part of the point image into the light beam around it. The peripheral light beam is split into a plurality of light beams by a light beam splitting element (such as an edge mirror) disposed at a fundus conjugate point newly formed by the imaging optical system. Each of the plurality of split light beams is received by the detector.

  At the fundus conjugate point, it is necessary to accurately divide the light flux at the center of the point image and the light flux around it. However, since the point image size (air disk diameter) at the fundus conjugate point is several tens to several hundreds of micrometers, extremely high precision is required for manufacturing and installing the light beam splitting element. As a result, the cost is increased and the time required for the alignment work is lengthened.

  In addition, since the above-described light beam splitting element is used, it is very difficult to change the number of divisions of the peripheral light beam. For example, when increasing the number of divisions, it is necessary to newly form a fundus conjugate point. This makes it difficult to secure an installation space by increasing the length of the optical system or providing detectors for the number of divisions. Conversely, the number of divisions may be restricted by the installation space.

  Further, in the conventional configuration, it is very difficult to change the division pattern such as the division direction of the peripheral light beam. For example, when changing the dividing direction, a new alignment operation with high accuracy is required.

  The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a new technique of a fundus imaging apparatus using a Split Detection method.

  The fundus imaging apparatus according to the embodiment includes a light source, an optical scanner, an optical fiber, a light guide system, a light detection unit, and an image forming unit. The optical scanner scans the fundus of the subject's eye with light from a light source. The optical fiber has a plurality of optical waveguides whose incident ends are optically conjugate with the fundus or at or near the positions. The light guide system guides the fundus reflected light from the fundus to the entrance end of the optical fiber. The light detection unit detects light emitted from at least three regions at the emission end of the optical fiber. The image forming unit forms a first image based on a detection result of light emitted from the first region among the at least three regions, and emits the first image from two or more regions other than the first region among the at least three regions. A second image is formed based on the detection result of the light. At least one incident end of the optical waveguide included in the first region is arranged on the optical axis of the light guide system.

  According to the embodiment, it is possible to provide a new technique of the fundus imaging apparatus using the Split Detection method.

It is a schematic diagram showing an example of composition of an optical system of a fundus imaging device concerning a 1st embodiment. FIG. 2 is an explanatory diagram of a multi-branch bundle fiber according to the first embodiment. FIG. 2 is an explanatory diagram of a multi-branch bundle fiber according to the first embodiment. FIG. 2 is a schematic diagram illustrating an example of a configuration of a processing system of the fundus imaging apparatus according to the first embodiment. It is an operation explanatory view of the fundus imaging apparatus according to the first embodiment. It is the schematic which shows an example of a structure of the optical system of the fundus imaging device which concerns on 2nd Embodiment. It is the schematic which shows an example of a structure of the processing system of the fundus imaging device concerning 2nd Embodiment. It is the schematic which shows an example of a structure of the optical system of the fundus imaging device which concerns on 3rd Embodiment. It is the schematic which shows an example of a structure of the optical system of the fundus imaging device which concerns on 3rd Embodiment. It is a schematic diagram showing an example of composition of a processing system of a fundus imaging device concerning a 3rd embodiment. It is the schematic which shows an example of a structure of the optical system of the fundus imaging device concerning 4th Embodiment.

  An embodiment of a fundus imaging apparatus according to the present invention will be described in detail with reference to the drawings. In addition, the description content of the document cited in this specification and any known technology can be used in the following embodiments.

  The fundus imaging apparatus is an apparatus that irradiates the fundus of the eye to be examined with light, receives reflected light (fundus reflected light, return light), and acquires an image representing the form of the fundus. Hereinafter, the fundus imaging apparatus according to the embodiment includes an optical system of a scanning laser ophthalmoscope that scans the fundus of an eye to be inspected with a laser beam and detects light reflected by the fundus with a light receiving device, and forms a front image of the fundus. It is possible.

[First Embodiment]
(Optical system)
FIG. 1 shows a configuration example of an optical system of the fundus imaging apparatus according to the first embodiment. FIG. 1 illustrates an example of the configuration of an optical system in a case where a peripheral light beam at the center of a point image at a fundus conjugate position is divided into two. In FIG. 1, a position optically conjugate with the fundus oculi Ef of the eye E is shown as a fundus conjugate position P, and a position optically conjugate with the pupil of the eye E is shown as a pupil conjugate position Q. .

  The optical system 100 includes an irradiation system 110, a light guide system 120, a multi-branch bundle fiber 140, and a detection system 150. The irradiation system 110 includes an optical system for irradiating the eye E with light. The light guide system 120 includes an optical system that guides light from the irradiation system 110 to the eye E and guides reflected light from the eye E to the input end of the multi-branch bundle fiber 140. The multi-branch bundle fiber 140 guides the fundus reflection light from the eye E to a plurality of emission ends. The detection system 150 detects the light guided by the multi-branch bundle fiber 140 as light at the center of the point image at the fundus conjugate point and light at the periphery thereof.

  The irradiation system 110 includes a light source 111, an optical fiber 112, and a lens 113. The light source 111 emits laser light having a wavelength component selected from a wavelength range of 500 nm to 900 nm, for example. Examples of the light source 111 include a laser diode (Laser Diode: LD), a super luminescent diode (Super Luminescent Diode: SLD), a laser driven light source (Laser Driven Light Source: LDLS), and the like. The laser light emitted from the light source 111 is not limited to light having a single wavelength, and may have a wavelength component having a certain bandwidth. The light emitted by the light source 111 may be light having high directivity (that is, light having a small divergence angle).

  The light source 111 is connected to an optical fiber 112 that guides laser light to the light guide system 120. The optical fiber 112 is a single mode fiber. The core diameter of the optical fiber 112 may be substantially equal to the spot diameter of the laser light emitted from the light source 111. At the output end of the optical fiber 112, a lens 113 for converting the laser light emitted from the optical fiber 112 into a parallel light beam is disposed. The laser light that has passed through the lens 113 is guided to a beam splitter 121 included in the light guide system 120.

  The beam splitter 121 is an optical path coupling member that couples the optical path of the irradiation system 110 to the optical path of the light guide system 120. The beam splitter 121 reflects the laser light passing through the lens 113 toward the mirror 122, and transmits the fundus reflection light from the eye E to be guided to the condenser lens 123.

  An optical scanner 125 is disposed on the mirror E side of the subject's eye E via a lens system 124 for adjusting a light flux. The optical scanner 125 is used for scanning the fundus oculi Ef of the eye E with laser light from the light source 111. The optical scanner 125 includes a vertical optical scanner 125V and a horizontal optical scanner 125H. The vertical direction optical scanner 125V is a mirror whose inclination can be varied, and the inclination of the reflection surface is controlled by a control unit 200 described later. The vertical direction optical scanner 125V is used for, for example, vertical scanning in the fundus oculi. The vertical light scanner 125V may be a low-speed scanner such as a galvanometer mirror. A horizontal optical scanner 125H is disposed on the side of the eye E of the vertical optical scanner 125V via a lens system 126. The horizontal optical scanner 125H is a mirror whose inclination can be varied, and the inclination of the reflection surface is controlled by the control unit 200. The horizontal optical scanner 125H is used, for example, for horizontal scanning in the fundus oculi, which is orthogonal to the vertical direction. One of the vertical optical scanner 125V and the horizontal optical scanner 125H may be a high-speed scanner such as a resonant mirror or a MEMS (Micro Electro Mechanical Systems) mirror. The reflection surface of the vertical light scanner 125V and the reflection surface of the horizontal light scanner 125H are arranged at or near a position optically conjugate to the pupil of the eye E (pupil conjugate position).

  A diopter correction mechanism 128 is disposed on the side of the eye E of the horizontal optical scanner 125H via a lens 127. The diopter correction mechanism 128 is an example of an adjusting unit that adjusts the laser light so as to irradiate the laser light onto the fundus oculi Ef as a substantially point image. The diopter correction mechanism 128 continuously moves the position of the fundus conjugate point according to the refractive power of the eye E. The diopter correction mechanism 128 includes V-shaped diopter correction mirrors 129 and 130. By moving the diopter correction mirror 130 relatively to and away from the diopter correction mirror 129, adjustment is performed so that the focal point of the optical system 100 is located at the fundus oculi Ef. That is, although there is an individual difference or an individual difference in the diopter, even if there is a difference in the diopter, by moving the position of the diopter correction mirror 130, the focal point of the optical system 100 is positioned on the fundus oculi Ef. That is, the irradiation light is adjusted so as to be condensed and irradiated as a substantially point image on the fundus oculi Ef. In the diopter correction mechanism 128, the pupil of the eye E has a conjugate relationship with infinity, so that the movement of the diopter correction mirror 130 does not change the pupil conjugate relationship in the optical system 100.

  Mirrors 132 and 133 are arranged on the eye E side of the diopter correction mechanism 128 via a lens system 131. An objective lens 134 is disposed on the mirror 133 on the side of the eye E to be examined. The objective lens 134 has a structure in which a plurality of lenses are combined in order to suppress aberrations (of course, the objective lens 134 may be constituted by a single lens).

  The fundus reflection light from the subject's eye E travels in the reverse direction on the path of the laser light from the objective lens 134 to the beam splitter 121, and is condensed by passing through the condenser lens 123. The optical elements of the light guide system 120 are arranged such that the light condensing position of the light condensing lens 123 is at or near the fundus conjugate position P. The incident end of the multi-branch bundle fiber 140 is arranged at the light condensing position (fundus conjugate position P) by the light condensing lens 123. The multi-branch bundle fiber 140 is an optical fiber in which a plurality of fiber cores (optical waveguides) are bundled into one on the input end side, and the plurality of fiber cores are divided into a plurality of small bundles on the output end side. .

  2 and 3 are explanatory diagrams of the multi-branch bundle fiber 140 according to the embodiment. FIG. 2 schematically illustrates a configuration example of the multi-branch bundle fiber 140 having three branches. FIG. 3 schematically shows an example of the arrangement of the fiber cores on the incident end face of the multi-branch bundle fiber 140 shown in FIG.

  The connector 141A is provided on the input end side of the multi-branch bundle fiber 140, and the connectors 141B, 141D, 141E are provided on the output end side. One end of a flexible tube 142 such as a SUS (Stainless Used Steel) flexible tube into which (2 × N (N is a positive integer) +1) fiber cores are inserted is connected to the connector 141A. . Each of the connectors 141A to 141D is detachable from the corresponding connector. Each of the connectors 141A to 141D is, for example, an FC connector. This makes it possible to maintain an appropriate connection state by the screw fixing method, and facilitates replacement with another multi-branch bundle fiber having a different division method and the number of divisions.

  The (2 × N + 1) fiber cores are divided into three small bundles composed of one fiber core (center core) and two types of N fiber cores while being held by the branch fitting 143. . Each small bundle is also inserted through a flexible tube such as a SUS flexible tube. The connector 141B is connected to the other end of the flexible tube through which one fiber core is inserted. Each of the connectors 141C and 141D is connected to the other end of the flexible tube through which the N fiber cores are inserted. Thus, each of the connectors 141B to 141D can be attached to a connector arranged at an arbitrary position.

  As shown in FIG. 3, one central core (one fiber core) whose other end is connected to the connector 141B is arranged in the central region F1 on the incident end face of the multi-branch bundle fiber 140. The incident end of the center core is arranged on the optical axis of the light guide system 120. N fiber cores connected to the connector 141C are arranged in the peripheral division area F2 on the incident end face of the multi-branch bundle fiber 140. N fiber cores connected to the connector 141D are arranged in the peripheral division region F3 on the incident end face of the multi-branch bundle fiber 140. Thereby, the light beam incident on the central region F1 on the incident end face of the multi-branch bundle fiber 140 is guided to the connector 141B by the central core. The light beam incident on the peripheral divided region F2 is guided to the connector 141C by N fiber cores, and the light beam incident on the peripheral divided region F3 is guided to the connector 141D by the N fiber cores.

  At the incident end face of the multi-branch bundle fiber 140, a method of dividing the (2 × N) fiber cores into a plurality of small bundles excluding the center core of the central region F1 is arbitrary. That is, the shape is not limited to the shape of the peripheral divided area on the incident end face. For example, the fiber core excluding the center core can be divided into two in the left-right direction, four in the up-down direction and the left-right direction, and eight in a radial pattern.

  In addition, FIGS. 2 and 3 show an example in which the image is divided into two small bands, but the number of divisions into small bundles may be three or more. The number of fiber cores constituting each of the plurality of small bundles may not be the same. Each fiber core constituting the multi-branch bundle fiber 140 may be a single mode fiber or a multimode fiber. Further, the diameter of the center core and the diameter of the other fiber cores may be different from each other.

  The input end side (connector 141A) of the multi-branch bundle fiber 140 may be rotatable about its optical axis. In this case, the fundus imaging apparatus according to the embodiment includes a rotation mechanism (second mechanism) that rotates the incident end side of the multi-branch bundle fiber 140. For example, the user can manually rotate the connector 141A around the optical axis of the center core by the rotation mechanism. Thereby, the division direction of the peripheral division area shown in FIG. 3 can be changed while looking at a phase contrast image described later, so that the adjustment of the division direction for obtaining a desired image becomes easy.

  The connector 141A may be provided with a key (for example, keys G1 and G2 in FIG. 3) at a position corresponding to the boundary of the peripheral divided area. Thus, the user can rotate the connector 141A while checking the division direction of the peripheral division area at the position of the key.

  At the emission end of the multi-branch bundle fiber 140 as described above, a detection system 150 is provided as shown in FIG. The detection system 150 detects the light emitted from the emission end of the multi-branch bundle fiber 140, respectively. Since the exit end of the multi-branch bundle fiber 140 is divided into at least three regions, the detection system 150 can detect light emitted from at least three regions at the exit end of the multi-branch bundle fiber 140, respectively. is there. In this embodiment, the detection system 150 includes a relay optical system and a photodetector corresponding to each of the emission ends of the multi-branch bundle fiber 140. Specifically, the detection system 150 includes relay optical systems 151B to 151D and photodetectors 152B to 152D.

  A relay optical system 151B and a photodetector 152B are provided corresponding to the connector 141B. The relay optical system 151B is an optical system for relaying a fundus conjugate point of light emitted from the connector 141B. The photodetector 152B is a photodetector that detects light emitted from the connector 141B. The light detection surface of the light detector 152B is arranged at a fundus conjugate position. The photodetector 152B includes, for example, an avalanche photodiode (APD) or a photomultiplier tube (PhotoMultiplier Tube: PMT). The detection result of the fundus reflection light from the fundus oculi Ef of the eye E by the photodetector 152B is used for forming an SLO image (confocal image) as the light detection result of the central part of the point image at the fundus conjugate point.

  A relay optical system 151C and a photodetector 152C are provided corresponding to the connector 141C. The relay optical system 151C is an optical system for relaying a fundus conjugate point of light emitted from the connector 141C. The photodetector 152C is a photodetector that detects light emitted from the connector 141C. The light detection surface of the light detector 152C is disposed at a fundus conjugate position. The light detector 152C has the same configuration as the light detector 152B.

  A relay optical system 151D and a photodetector 152D are provided corresponding to the connector 141D. The relay optical system 151D is an optical system for relaying a fundus conjugate point of light emitted from the connector 141D. The photodetector 152D is a photodetector that detects light emitted from the connector 141D. The light detection surface of the light detector 152D is disposed at a fundus conjugate position. The light detector 152D has the same configuration as the light detector 152B. The detection result of the fundus reflection light from the fundus oculi Ef of the eye E to be inspected by the photodetectors 152C and 152D forms a phase contrast image (nonconfocal image) as the detection result of the light around the center of the point image at the fundus conjugate point. Used for

  The multi-branch bundle fiber 140 is an example of the “optical fiber” according to the embodiment. The detection system 150 is an example of the “light detection unit” according to the embodiment. The central region F1 is an example of a “first region” according to the embodiment. The SLO image is an example of a “first image” according to the embodiment. The phase contrast image is an example of a “second image” according to the embodiment.

(Processing system)
FIG. 4 illustrates a configuration example of a processing system of the fundus imaging apparatus according to the first embodiment. In FIG. 4, the same parts as those in FIGS. 1 to 3 are denoted by the same reference numerals, and the description will be appropriately omitted.

  The processing system of the fundus imaging apparatus according to the first embodiment is mainly configured with a control unit 200. The control unit 200 controls each unit of the fundus imaging apparatus. The control unit 200 includes a microprocessor and a storage device. A computer program for controlling the fundus imaging device is stored in the storage device in advance. The computer programs include a light source control program, a diopter correction mechanism control program, an optical scanner control program, a detection system control program, an image forming program, a data processing program, a display control program, and a user interface program. And so on. When the microprocessor operates according to such a computer program, the control unit 200 executes a control process.

  The control of the optical system includes control of the light source 111, control of the optical scanner 125, control of the diopter correction mechanism 128 via the diopter correction mechanism driving unit 128A, control of the detection system 150, and the like. The control of the light source 111 includes turning on and off the light source, adjusting the light amount, adjusting the aperture, and the like. The control of the optical scanner 125 includes control of the scanning position and scanning range by the vertical optical scanner 125V, and control of the scanning position and scanning range by the horizontal optical scanner 125H. The control of the diopter correction mechanism 128 includes drive control for the diopter correction mechanism driving unit 128A according to the diopter. The control of the detection system 150 includes exposure adjustment, gain adjustment, and shooting rate adjustment.

  The image forming unit 210 forms an image based on the detection result of the fundus reflection light from the fundus oculi Ef of the eye E by the detection system 150. Image forming section 210 forms an SLO image based on the detection result of light emitted from the center core of central region F1 by photodetector 152B. For example, image forming section 210 forms image data of an SLO image based on a light receiving signal input from photodetector 152B and a pixel position signal input from control section 200.

  Further, the image forming unit 210 forms a phase contrast image based on the detection result of the light emitted from the fiber cores of the peripheral divided regions F2 and F3 by the photodetectors 152C and 152D in parallel with the formation of the SLO image. . For example, image forming section 210 performs arithmetic processing on the received light signals input from photodetectors 152C and 152D, and performs phase contrast based on the arithmetic processing result and the pixel position signal input from control section 200. Form image data for the image. For example, assuming that a detection signal obtained by the photodetector 152C is Ic and a detection signal obtained by the photodetector 152D is Id, the phase contrast image is obtained by calculating (Ic−Id) / (Ic + Id). It is possible to do.

  When the peripheral divided area is divided into three or more areas, the image forming unit 210 forms a phase contrast image based on detection results of light emitted from two or more areas except the central area F1. Is possible.

  When the incident end face of the multi-branch bundle fiber 140 is divided into four or more regions except for the central region (that is, the incident end surface has five or more regions), the image forming unit 210 emits light from four or more regions. It is possible to form a plurality of types of phase contrast images based on the light detection result. In this case, the detection system 150 detects light emitted from five or more regions at the emission end of the multi-branch bundle fiber 140, respectively. The image forming unit 210 forms two or more different phase contrast images based on detection results of light emitted from four or more areas other than the central area among the five or more areas. For example, as shown in FIG. 5, it is assumed that the incident end face of the multi-branch bundle fiber 140 is divided into four regions ARb to ARe except for the central region ARa. Assuming that detection signals obtained by the photodetectors corresponding to the regions ARb to ARe are Ib to Ie, the image forming unit 210 forms the first phase contrast image by obtaining the value of Expression (1). The first phase contrast image is an image obtained by vertically dividing the peripheral light flux at the center of the point image at the fundus conjugate position into two in the vertical direction.

  Further, the image forming section 210 forms the second phase contrast image by obtaining the value of Expression (2). The second phase contrast image is an image obtained by dividing the peripheral luminous flux at the center of the point image at the fundus conjugate position into two in the left-right direction.

  Further, the image forming unit 210 can form a plurality of phase contrast images having different division directions and the number of divisions of the peripheral divided regions by changing the combination of the peripheral divided regions. In this case, the division direction and the number of divisions of the peripheral division region can be changed without rotating the incident end side of the multi-branch bundle fiber 140.

  The data processing unit 220 performs various data processing. As an example of the data processing, there is processing for image data formed by the image forming unit 210 or another device. Examples of this processing include various types of image processing and diagnosis support processing such as image evaluation based on image data.

  The user interface (UI) unit 230 has a function for exchanging information between the user and the fundus imaging apparatus. The UI unit 230 includes a display device and an operation device (input device). The display device may include a display unit, and may include other display devices. The operating device includes various hardware keys and / or software keys. At least a part of the operation device and at least a part of the display device can be integrally formed. A touch panel display is one example.

  In addition, a drive unit that drives a rotation mechanism that rotates the input end side of the multi-branch bundle fiber 140 is provided, and the control unit 200 controls the drive unit, so that the input end side of the multi-branch bundle fiber 140 (connector 141A). Can be automatically rotated.

  In addition, a first mechanism that changes the relative position between the incident end of the multi-branch bundle fiber 140 and the light guide system 120 may be provided. The first mechanism can change the relative position between the center core of the multi-branch bundle fiber 140 and the optical axis of the light guide system 120. For example, the control unit 200 may control the first mechanism based on a detection result of the light emitted from the central region F1 (a detection result of the photodetector 152B). Thereby, the alignment time can be shortened.

  In the fundus imaging apparatus having the above-described configuration, the laser light that is the fundus irradiation light generated from the light source 111 is reflected by the beam splitter 121 toward the mirror 122. The laser light reflected by the mirror 122 is turned into scanning light by the optical scanner 125. The laser light deflected by the horizontal optical scanner 125H is guided to the objective lens 134 via the diopter correction mechanism 128 and the mirrors 132 and 133, and is applied to the fundus Ef of the eye E via the objective lens 134. At this time, the diopter correction mechanism 128 is adjusted so that the optical system 100 is focused on the fundus oculi Ef of the subject's eye E.

  The fundus reflection light reflected from the fundus oculi Ef of the subject's eye E follows the reverse path of the fundus irradiation light and is guided to the beam splitter 121. The fundus reflection light passes through the beam splitter 121 and is guided to the incident end of the multi-branch bundle fiber 140. At the input end of the multi-branch bundle fiber 140, the input end of the central core that guides the light flux of the central point image at the fundus conjugate position, and two or more small bundles that guide the light flux of the peripheral portion of the central point image And the input end of the fiber core. The light beam incident on the incident end of the center core is guided to the photodetector 152B and used for forming an SLO image. The light beams incident on the incident ends of the fiber cores of the two or more small bundles are guided to, for example, photodetectors 152C and 152D and used for forming a phase contrast image.

[effect]
The effect of the fundus imaging device of the present embodiment will be described.

  The fundus imaging apparatus according to the embodiment includes a light source (light source 111), an optical scanner (optical scanner 125), an optical fiber (multi-branch bundle fiber 140), a light guide system (light guide system 120), and a light detection unit. (Detection system 150) and an image forming unit (image forming unit 210). The optical scanner scans the fundus (fundus Ef) of the eye to be inspected (eye E to be inspected) with light from a light source. The optical fiber has a plurality of optical waveguides (center core, fiber core). The light guide system guides the fundus reflected light from the fundus to the entrance end of the optical fiber. The light detection unit detects light emitted from at least three regions at the emission end of the optical fiber. The image forming unit forms a first image (SLO image) based on a detection result of light emitted from a first region (central region F1) of the at least three regions, and forms a first image (SLO image) of the at least three regions. A second image (phase contrast image) is formed based on detection results of light emitted from two or more regions (peripheral divided regions F2 and F3) other than the region.

  According to such a configuration, it is necessary to arrange the position of the input end and the position of the output end of the optical fiber with high precision, but without providing a light beam splitting element, for example, at the center of a point image. It is possible to separate and acquire the light beam and the light beam in the peripheral portion of the point image center. In addition, when increasing the number of divisions of the light flux around the center of the point image, it is necessary to form a fundus conjugate point corresponding to the number of divisions in the conventional configuration, which increases the length of the optical system. It is not necessary to increase the number of conjugate points of the fundus.

  In addition, the degree of freedom in arranging the optical system is increased within the range of the fiber length of the optical fiber, and the space can be saved. In addition, the arrangement of the optical waveguides at the incident end face of the optical fiber can be freely designed with respect to the optical waveguides constituting the small bundle and the number of divisions. Is easy to have. Further, regardless of the number of divisions, the light for forming the first image and the light for forming the second image can be detected at the same time, so that there is no need to align the two images. For example, it is easy to superimpose the first image and the second image.

  Further, in the fundus imaging apparatus according to the embodiment, at least one incident end of the optical waveguide included in the first region may be arranged on the optical axis of the light guide system.

  According to such a configuration, it is possible to detect the light flux guided by the optical waveguide included in the first region as the light flux at the center of the point image.

  Further, the fundus imaging apparatus according to the embodiment may include a first mechanism and a control unit (control unit 200). The first mechanism changes a relative position between the incident end of the optical fiber and the light guide system. The control unit controls the first mechanism based on a detection result of the light emitted from the first region.

  According to such a configuration, for example, while detecting an increase or decrease in the amount of light emitted from the optical waveguide in the first region, the incidence end of the optical fiber is accurately positioned with respect to a desired position (for example, a fundus conjugate position). The alignment can be performed well. In addition, if the first region can be correctly positioned, the other regions can be accurately positioned, and the time required for the alignment operation can be reduced even if the number of divisions is large.

  Further, the fundus imaging apparatus according to the embodiment may include a second mechanism. The second mechanism rotates the incident end side of the optical fiber.

  According to such a configuration, since the rotation of the incident end side of the optical fiber becomes easy, for example, it is also possible to divide the peripheral luminous flux at the center of the point image into a desired direction while referring to the phase contrast image. .

  In the fundus imaging apparatus according to the embodiment, the light detection unit detects light emitted from five or more regions at the emission end, and the image forming unit detects four or more regions other than the first region. It is possible to form two or more different second images based on the detection results of the light emitted from the above regions.

  According to such a configuration, by changing the combination of four or more regions other than the first region, the method of dividing the luminous flux around the central point image and the number of divisions can be easily changed, and various phase contrasts can be obtained. Images can be obtained.

  Further, in the fundus imaging apparatus according to the embodiment, the incident end of the optical fiber may be disposed at a position optically conjugate with the fundus or in the vicinity thereof.

  According to such a configuration, it is possible to detect the light flux guided by the optical waveguide included in the first region as the light flux at the center of the point image at the fundus conjugate position.

  In the fundus imaging apparatus according to the embodiment, the light detection unit may include three or more light detectors (light detectors 152B to 152D) that detect light emitted from at least three regions, respectively.

  According to such a configuration, it is possible to detect the luminous flux around the central part of the point image for each area.

[Second embodiment]
In the first embodiment, the case where the optical system of the fundus imaging apparatus includes the SLO optical system has been described, but the optical system of the fundus imaging apparatus according to the embodiment is not limited to the SLO optical system. In the second embodiment, the optical system of the fundus imaging apparatus includes an adaptive optics scanning laser ophthalmoscope (hereinafter, AO-SLO).

  The configuration of the fundus imaging apparatus according to the second embodiment is almost the same except that an adaptive optics system is added to the configuration of the fundus imaging apparatus according to the first embodiment. Hereinafter, the fundus imaging apparatus according to the second embodiment will be described focusing on differences from the first embodiment.

  FIG. 6 illustrates a configuration example of an optical system of a fundus imaging apparatus according to the second embodiment. 6, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the description will be appropriately omitted.

  The configuration of the optical system 100a according to the second embodiment is different from the configuration of the optical system 100 according to the first embodiment in that an irradiation system 110a is provided instead of the irradiation system 110 and that the light guide system 120 is replaced. This is the point where the light guide system 120a is provided, and the point where the wavefront detection system 160 is added. In the light guide system 120a, a deformable mirror 170 is provided instead of the mirror 122. In the irradiation system 110 a, a half mirror 172 is provided between the lens 113 and the beam splitter 121, and the fundus reflection light from the fundus oculi Ef of the eye E is guided to the wavefront detection system 160.

  The half mirror 172 is a light amount split mirror that branches the irradiation system 110a and the wavefront detection system 160. The wavefront detection system 160 is an optical system for detecting wavefront information from reflected light (detection light) from the fundus oculi Ef of the eye E to be inspected. The half mirror 172 transmits a part of the laser light from the light source 111 to the beam splitter 121 side, and reflects a part of the detection light incident from the beam splitter 121 side toward the wavefront detection system 160. Note that the branch ratio of the half mirror 172 is not limited to 1: 1.

  The wavefront detection system 160 includes a wavefront detection unit 161 and a pair of lenses 164. The wavefront detection unit 161 is a Shack-Hartmann sensor including a CCD 162 as an imaging device and a lens array 163 disposed in front of the CCD 162. The lens array 163 is configured by arranging small lenses in a lattice shape, and divides incident light into a large number of light beams and condenses each of the light beams. By imaging the focal point of the lens array 163 with the CCD 162 and analyzing the focal position of each lens, the wavefront aberration of the light incident on the lens array 163 can be detected. That is, by observing the reflected image from the fundus oculi Ef of the eye E through the lens array 163, it is possible to detect the disturbance of the wavefront in the reflected image. The image obtained by the CCD 162 is sent to an image analyzing unit such as the control unit 200a, the image forming unit 210, or the data processing unit 220. The image analyzing unit analyzes the wavefront disturbance, and a control signal (feedback) based on the analysis result. Signal) is sent to the deformable mirror 170.

  A confocal stop may be arranged at a fundus conjugate position P between the pair of lenses 164.

  The beam splitter 121 is a light amount split mirror that branches the irradiation system 110a, the detection system 150, and the multi-branch bundle fiber 140. A deformable mirror 170 is disposed on the side of the eye E of the beam splitter 121. The deformable mirror 170 is a deformable mirror for performing wavefront correction. The deformable mirror 170 is a mirror whose surface shape can be deformed by a plurality of actuators. The deformable mirror 170 is driven by a control signal based on the analysis result of an image formed using the detection result of the CCD 162. For example, when the captured image based on the detection result of the CCD 162 has distortion (wavefront distortion), the surface shape of the deformable mirror 170 is deformed so as to reduce the distortion. That is, the surface shape of the deformable mirror 170 is deformed by the feedback control such that the distortion of the image of the fundus oculi Ef based on the detection results by the photodetectors 152B to 152D is reduced, and the distortion of the image of the fundus oculi Ef is suppressed. Is done.

  FIG. 7 illustrates a configuration example of a processing system of the fundus imaging apparatus according to the second embodiment. In FIG. 7, the same parts as those in FIGS. 4 and 6 are denoted by the same reference numerals, and the description will be appropriately omitted.

  The control unit 200a controls the CCD 162 and the deformable mirror 170 in addition to the same control as the control unit 200. The control of the CCD 162 includes exposure adjustment, gain adjustment, and shooting rate adjustment. The control of the deformable mirror 170 includes drive control for a plurality of actuators based on the detection result of the CCD 162.

  In the second embodiment, when the fundus reflection light from the fundus oculi Ef of the eye E reaches the beam splitter 121, it is branched there, one is guided to the half mirror 172, and the other is guided to the condenser lens 123. The half mirror 172 reflects the fundus reflection light toward the wavefront detection system 160 and is detected by the wavefront detection unit 161. When the wavefront detection unit 161 detects the state of the wavefront of the fundus reflected light, the control unit 200a executes control to change the surface shape of the deformable mirror 170 so as to correct the distortion.

  According to the fundus imaging apparatus having the above-described configuration, it is possible to form an SLO image compensated by the adaptive optics system and obtain the same effect as that of the first embodiment.

[Third embodiment]
In the third embodiment, the optical system of the fundus imaging apparatus includes an SLO optical system and an optical coherence tomography (OCT) optical system.

  The configuration of the fundus imaging apparatus according to the third embodiment is almost the same except that an OCT optical system is added to the configuration of the fundus imaging apparatus according to the first embodiment. Hereinafter, the fundus imaging apparatus according to the third embodiment will be described focusing on differences from the first embodiment.

  8 and 9 show a configuration example of an optical system of a fundus imaging apparatus according to the third embodiment. FIG. 8 shows an overall configuration example of an optical system 100b according to the third embodiment. FIG. 9 illustrates a configuration example of the OCT optical system 300 in FIG. 8, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description will be appropriately omitted.

  The configuration of the optical system 100b according to the third embodiment is different from the configuration of the optical system 100 according to the first embodiment in that a light guide system 120b is provided instead of the light guide system 120 and that the OCT optical system 300 Is added. In the light guide system 120b, a dichroic mirror 180 is provided between the mirror 122 and the lens system. The dichroic mirror 180 transmits laser light from the light source 111 and transmits reflected light from the fundus Ef of the eye E to be examined. The dichroic mirror 180 reflects the measurement light LS from the OCT optical system 300 to be described later toward the optical scanner 125, and reflects the return light of the measurement light LS from the eye E to the OCT optical system 300. .

  The OCT optical system 300 is provided with an optical system for acquiring an OCT image of a measurement site such as the fundus oculi Ef. This optical system has a configuration similar to that of a conventional Fourier domain type OCT apparatus. That is, this optical system divides the light (low coherence light) from the OCT light source into the reference light LR and the measurement light LS, and returns the return light of the measurement light LS via the fundus Ef and the reference light LR via the reference optical path. Are made to interfere with each other to generate interference light LC, and the spectral components of the interference light LC are detected. This detection result (detection signal) is sent to the image forming unit 210c.

  The OCT light source 301 outputs broadband low coherence light L0. The low coherence light L0 has a wavelength different from that of the laser light emitted from the light source 111, for example, has a wavelength component of 1000 nm, and has a wavelength width of about 50 nm. The OCT light source 301 includes an optical output device such as a super luminescent diode (Super Luminescent Diode: SLD). In this embodiment, a spectral domain type is particularly described. However, when a swept source type is applied, a laser light source capable of wavelength sweeping is used as the OCT light source 301. Generally, the configuration of the OCT light source 301 is appropriately selected according to the type of optical coherence tomography.

  The low coherence light L0 output from the OCT light source 301 is guided to a fiber coupler 303 by an optical fiber 302 and split into a measurement light LS and a reference light LR.

  The measurement light LS is guided by the optical fiber 304 and becomes a parallel light beam by the collimator lens 305. The optical path of the measurement light LS is coupled by the dichroic mirror 180 to the optical path of the above-mentioned SLO optical system. The measurement light LS applied to the fundus oculi Ef via the above-described optical path is scattered and reflected at a measurement site such as the fundus oculi Ef. The scattered light and the reflected light may be collectively referred to as return light of the measurement light LS. The return light of the measurement light LS travels in the same path in the opposite direction and is guided to the fiber coupler 303.

  The reference light LR is guided by the optical fiber 306 and becomes a parallel light beam by the collimator lens 307. Further, the reference light LR is attenuated by an ND (Neutral Density) filter 308, is reflected by the corner cube 309 in the opposite direction, and is imaged on the reflection surface of the reference mirror 311 by the collimator and the lens 310. The reference system unit including the corner cube 309 is integrally movable along the traveling direction of the reference light LR. The axial length can be corrected by moving the reference unit. The reference light LR reflected by the reference mirror 311 travels in the same path in the opposite direction and is guided to the fiber coupler 303. Note that an optical element for dispersion compensation (such as a pair prism) or an optical element for polarization correction (such as a wavelength plate) may be provided in the optical path (reference optical path) of the reference light LR.

  The fiber coupler 303 combines the return light of the measurement light LS with the reference light LR reflected by the reference mirror 311. The interference light LC generated by this is guided by the optical fiber 312 and emitted from the emission end 313. Further, the interference light LC is converted into a parallel light beam by the collimating lens 314, is separated (spectral resolution) by the diffraction grating 315, is collected by the collecting lens 316, and is projected on the light receiving surface of the CCD 317. Although the diffraction grating 315 shown in FIG. 9 is a reflection type, a transmission type diffraction grating may be used.

  The CCD 317 is, for example, a line sensor, and detects each spectral component of the separated interference light LC and converts it into electric charge. The CCD 317 accumulates this charge and generates a detection signal. Further, the CCD 317 sends this detection signal to the image forming unit 210c.

  In this embodiment, a Michelson-type interferometer is used, but any type of interferometer, such as a Mach-Zehnder type, can be used as appropriate. Further, instead of the CCD image sensor, another type of image sensor, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor can be used.

  FIG. 10 illustrates a configuration example of a processing system of the fundus imaging apparatus according to the third embodiment. In FIG. 10, the same parts as those in FIGS. 4, 8, and 9 are denoted by the same reference numerals, and the description will be appropriately omitted.

  The control unit 200c controls the OCT optical system 300 and the image forming unit 210c that forms an OCT image, in addition to the control by the control unit 200. The control of the OCT optical system 300 includes control of the OCT light source 301, control of the reference drive unit 320, control of the CCD 317, and the like. The control of the OCT light source 301 includes turning on and off the light source, adjusting the amount of light, adjusting the aperture, and the like. The control of the reference driving unit 320 includes a control of moving the reference unit along the traveling direction of the reference light LR. The control of the CCD 317 includes exposure adjustment, gain adjustment, and shooting rate adjustment.

  The image forming unit 210c can form an OCT image in addition to forming the SLO image and the phase contrast image described above. The image forming unit 210c forms image data of a tomographic image of the fundus oculi Ef based on the detection signal from the CCD 317. This processing includes processing such as noise removal (noise reduction), filter processing, and FFT (Fast Fourier Transform), similarly to the conventional Fourier domain type optical coherence tomography. Note that the data processing unit 220 can form image data of a three-dimensional image of the fundus oculi Ef by performing known image processing such as interpolation processing for interpolating pixels between tomographic images. The image data of a three-dimensional image means image data in which the positions of pixels are defined by a three-dimensional coordinate system. As image data of a three-dimensional image, there is image data composed of voxels arranged three-dimensionally. This image data is called volume data or voxel data. When displaying an image based on the volume data, the data processing unit 220 performs rendering processing (such as volume rendering or MIP (Maximum Intensity Projection: maximum value projection)) on the volume data to view the volume data from a specific line of sight. The image data of the pseudo three-dimensional image at the time of being formed is formed. The pseudo three-dimensional image is displayed on the display device of the UI unit 230.

  Also, stack data of a plurality of tomographic images can be formed as image data of a three-dimensional image. Stack data is image data obtained by three-dimensionally arranging a plurality of tomographic images obtained along a plurality of scanning lines based on the positional relationship of the scanning lines. That is, the stack data is image data obtained by expressing a plurality of tomographic images originally defined by individual two-dimensional coordinate systems in one three-dimensional coordinate system (that is, embedding them in one three-dimensional space). is there.

  According to the fundus imaging apparatus having the above-described configuration, an OCT image can be obtained, and the same effect as that of the first embodiment can be obtained.

[Fourth embodiment]
The fundus imaging apparatus according to the embodiment may have a configuration in which the first to third embodiments are arbitrarily combined. In the fourth embodiment, the optical system of the fundus imaging apparatus includes an AO-SLO and an OCT optical system.

  The configuration of the fundus imaging apparatus according to the fourth embodiment is substantially the same as that of the fundus imaging apparatus according to the second embodiment except that the OCT optical system 300 according to the third embodiment is added. Hereinafter, the fundus imaging apparatus according to the fourth embodiment will be described focusing on differences from the second embodiment and the third embodiment.

  FIG. 11 shows a configuration example of an optical system of a fundus imaging apparatus according to the fourth embodiment. In FIG. 11, the same parts as those in FIGS.

  The configuration of the optical system 100c according to the fourth embodiment differs from the configuration of the optical system 100a according to the second embodiment in that a light guide system 120c is provided instead of the light guide system 120a. In the light guide system 120c, a dichroic mirror 180 is provided between the deformable mirror 170 and the lens system 124. The dichroic mirror 180 transmits laser light from the light source 111 and transmits reflected light from the fundus Ef of the eye E to be examined. The dichroic mirror 180 reflects the measurement light LS from the OCT optical system 300 toward the optical scanner 125 and reflects the return light of the measurement light LS from the subject's eye E toward the OCT optical system 300.

  In the processing system of the fundus imaging apparatus according to the fourth embodiment, the control unit executes control of the OCT optical system 300 by the control unit 200b shown in FIG. 8 in addition to the control of the control unit 200a shown in FIG. Others are the same as the second embodiment and the third embodiment.

  According to the fundus imaging apparatus having the above-described configuration, it is possible to acquire the SLO image and the OCT image compensated by the adaptive optics system and to obtain the same effect as that of the first embodiment.

  In the above-described embodiment, the case where the optical system is configured by a refraction system has been described, but the optical system may be configured by a reflection system.

  In the above-described embodiment, the description has been given of the configuration in which the detection system 150 is provided with the photodetector for each of the emission ends of the multi-branch bundle fiber 140. It is not limited. For example, the detection system 150 may have a configuration in which one photodetector is provided corresponding to a plurality of emission ends of the multi-branch bundle fiber 140. In this case, one photodetector can detect light emitted from a plurality of emission ends in a time-division manner to detect light for each emission end. Alternatively, the detection surface of one photodetector may be divided and light may be detected for each emission end.

  In the above-described embodiment, the multi-branch bundle fiber may be a multi-branch image fiber provided with a plurality of emission ends.

Reference Signs List 100 optical system 110 irradiation system 111 light source 120 light guide system 125 optical scanner 140 multi-branch bundle fiber 150 detection system 210 image forming unit E eye Ef fundus oculi conjugate position Q pupil conjugate position

The fundus imaging apparatus according to the embodiment includes a light source, an optical scanner, an optical fiber, a light guide system, a light detection unit, a second mechanism, and an image forming unit. The optical scanner scans the fundus of the subject's eye with light from a light source. The optical fiber has a plurality of optical waveguides whose incident ends are optically conjugate with the fundus or at or near the positions. The light guide system guides the fundus reflected light from the fundus to the entrance end of the optical fiber. The light detection unit detects light emitted from at least three regions at the emission end of the optical fiber. The second mechanism changes the division direction of two or more regions other than the first region among the at least three regions by rotating the incident end side of the optical fiber. The image forming unit forms a first image based on the detection result of the light emitted from the first region, and forms a second image based on the detection result of the light emitted from the two or more regions.

Claims (5)

A light source,
An optical scanner that scans the fundus of the subject's eye with light from the light source,
An optical fiber having a plurality of optical waveguides in which the incident end is optically conjugate with the fundus or at or near the position,
A light guide system that guides return light from the fundus to the incident end of the optical fiber,
A light detection unit that detects light emitted from at least three regions at the emission end of the optical fiber,
A first image is formed based on a detection result of light emitted from a first area of the at least three areas, and emitted from two or more areas other than the first area among the at least three areas. An image forming unit that forms a second image based on a light detection result;
Including
The fundus imaging apparatus, wherein at least one incident end of the optical waveguides included in the first region is disposed on an optical axis of the light guide system. A first mechanism for changing a relative position between an incident end of the optical fiber and the light guide system,
A control unit that controls the first mechanism based on a detection result of light emitted from the first region;
The fundus imaging apparatus according to claim 1, comprising: The fundus photographing apparatus according to claim 1, further comprising a second mechanism that rotates a light incident end side of the optical fiber. The light detection unit detects light emitted from five or more regions at the emission end,
The image forming unit can form two or more different second images based on detection results of light emitted from four or more regions other than the first region among the five or more regions. The fundus photographing apparatus according to any one of claims 1 to 3. The fundus imaging according to any one of claims 1 to 4, wherein the light detection unit includes three or more light detectors that respectively detect light emitted from the at least three regions. apparatus.

Images