JP2017127459A - Fundus imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fundus imaging apparatus capable of imaging ocular fundus with high resolution by a confocal image detection system and a non-confocal image detection system.SOLUTION: A fundus imaging apparatus includes a light source, an illumination optical system for scanning the light from the light source on an eye to be examined, a confocal image detection system and a non-confocal image detection system for taking a confocal image and a non-confocal image of ocular fundus respectively based on the light from the ocular fundus, a light receiving optical system including an optical path in common with the illumination optical system for guiding the light from the ocular fundus to the confocal image detection system and the non-confocal image detection system, a polarization beam splitter disposed in the common optical path for transmitting a light of a linear polarization component in a first polarization direction of the light from the light source, and reflecting a light of a linear polarization component in a second polarization direction orthogonal to the first polarization direction, a λ/4 plate disposed between the polarization beam splitter and the eye to be examined in the common optical path, and a polarization element disposed in an optical path of the non-confocal image detection system for transmitting a light of a linear polarization component orthogonal to a light of a linear polarization component guided by the λ/4 plate from the polarization beam splitter.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fundus imaging apparatus.

  SLO (Scanning Laser Ophthalmoscope) that can acquire a two-dimensional image as one of fundus imaging devices that non-invasively acquire an image of an object to be inspected (for example, a living tissue of the fundus including the retina of the eye) Glasses) are known. The SLO scans light on the retina using a deflector, detects reflected or scattered light, and forms a two-dimensional image. In addition, regarding SLO, an apparatus using a wavefront aberration corrector that detects a wavefront disturbed in an eyeball using an adaptive optics (AO: Adaptive Optics) technique and cancels the wavefront has been proposed.

  In the fundus imaging apparatus, the following method has been proposed in order to accurately detect weak light from the fundus. Non-Patent Document 1 describes a method for detecting weak light from the fundus using a confocal image detection system and a non-confocal image detection system having a deep depth of field compared to the confocal image detection system. Has been. Specifically, a confocal image detection system is used to detect light from the fundus and generate a confocal image, while a non-confocal image detection system is used to divide and detect light from the fundus. A difference image (non-confocal image) is generated from the difference in intensity. As a result, the fundus image information can be acquired with high resolution by acquiring the confocal image and the difference image related to the non-confocal image from the weak light from the fundus.

  Here, when detecting light from the fundus, if unnecessary reflected light or scattered light from each surface of the optical member or the eye reaches the detection surface of the light receiving element, the light detection accuracy decreases and the image There is a problem that the resolution is lowered. Therefore, in order to solve the problems associated with the detection of unnecessary light, methods for reducing unnecessary light using the polarization characteristics of light used for imaging have been proposed.

  Patent Document 1 describes an apparatus for measuring optical characteristics of an eye using a confocal image detection system including a polarizing beam splitter and a λ / 4 plate. In Patent Document 1, a polarization beam splitter and a λ / 4 plate are used to separate reflected light from the fundus surface and unnecessary light scattered and reflected at a position on the inner side by a minute amount from the fundus surface. Thereby, unnecessary light is blocked and only the reflected light from the fundus surface is detected by the photoelectric detector, so that the eye optical characteristics can be measured with high accuracy.

  However, in the method of blocking unnecessary light using a polarizing beam splitter and a λ / 4 plate, unnecessary light with low intensity may be detected by the light receiving element due to the characteristics of the extinction ratio of the polarizing beam splitter. For this reason, in the non-confocal image detection system, there is a problem that an error caused by unnecessary light occurs in the difference image generated from the difference value of the intensity of the light detected by dividing, and the detection accuracy is lowered. To do.

  In addition, when a polarizing plate is used in place of the polarizing beam splitter and unnecessary light is blocked by the polarizing plate and the λ / 4 plate, the intensity of light from the fundus is reduced along with the unnecessary light. Here, in the confocal image detection system, when the detection intensity of light from the fundus decreases, the S / N ratio of the detected signal decreases due to the influence of errors generated in the light source, the compensation optical system, the light receiving element, and the like. As a result, the detection accuracy decreases.

Japanese Patent No. 4618592

In Vivo Imaging of Human Cone Photoceptor Inner Segments (Invest Optalmol Vis Sci. 2014: 55: 4244-4251.DOI: 10.1167 / iovs.14-14542)

  In view of the above circumstances, the present invention provides a fundus imaging apparatus capable of imaging the fundus with high resolution using a confocal image detection system and a non-confocal image detection system.

  A fundus imaging apparatus according to an embodiment of the present invention includes a light source, an illumination optical system that scans the eye to be examined by irradiating light from the light source, and light from the fundus of the eye to be examined. A confocal image detection system that captures a confocal image of the fundus of the optometry, a non-confocal image detection system that captures a non-confocal image of the fundus based on light from the fundus, and the illumination optical system A light receiving optical system that includes a common optical path and guides light from the fundus to the confocal image detection system and the non-confocal image detection system, and is disposed in the common optical path of the illumination optical system and the light receiving optical system, A polarization beam splitter that transmits light of a linearly polarized light component in a first polarization direction out of light from the light source and reflects light of a linearly polarized light component in a second polarization direction orthogonal to the first polarization direction; , In the common optical path, the polarizing beam splitter and the A λ / 4 plate disposed between the optometry and the first or second polarization direction disposed in the optical path of the non-confocal image detection system and guided from the polarization beam splitter to the λ / 4 plate. A polarizing element that transmits light of a linearly polarized light component orthogonal to the light of the linearly polarized light component.

  According to the present invention, it is possible to provide a fundus imaging apparatus that images the fundus of a subject with high resolution using a confocal image detection system and a non-confocal image detection system.

1 shows a schematic configuration of a fundus imaging apparatus according to a first embodiment of the present invention. It is a figure for demonstrating the fall of the detection accuracy in a fundus imaging device. 3 shows a schematic configuration of a fundus imaging apparatus according to a second embodiment of the present invention. It is a figure for demonstrating the relationship between the polarizing plate which concerns on 2nd Embodiment of this invention, and the angle of light. 4 shows a schematic configuration of a fundus imaging apparatus according to a third embodiment of the present invention. It is a figure for demonstrating the relationship between the polarizing plate which concerns on 3rd Embodiment of this invention, and the angle of light.

  Hereinafter, exemplary embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals are used in the drawings to denote the same or functionally similar elements, and redundant description is omitted. However, dimensions, materials, shapes, relative positions of components, and the like described in the following embodiments are arbitrary and can be changed according to the configuration of the apparatus to which the present invention is applied or various conditions. In addition, the confocal image described below is a confocal optical system configuration in which three of a light source, a test object, and a mirror member are arranged at conjugate positions. It means an image acquired when it is detected. In addition, the non-confocal image means an image obtained when the detector detects light that does not form an image on the mirror member in the above configuration.

[First Embodiment]
A schematic configuration of the imaging apparatus according to the first embodiment will be described with reference to FIG. FIG. 1A shows a schematic configuration of a fundus imaging apparatus 100 provided with an adaptive optics system according to the first embodiment. FIG. 1A shows light rays when imaging the fundus 20r of the eye 20 to be examined. As will be described later, the wavefront sensor or the like is disposed at a position conjugate with the eye pupil 20p, but the light shown in FIG. 1A is conjugated with the wavefront sensor or the like and the eye pupil 20p. Note that this is different from the rays that indicate that they are placed at different positions.

  The fundus imaging apparatus 100 is roughly divided into a light source 10, an illumination optical system 110 including a wavefront correction system 116 and a scanning system 117, a wavefront detection system 120, a light receiving optical system 130, a confocal image detection system 140, and a non-confocal image detection. A system 150, a control unit 160, and a display unit 170 are provided.

  The light emitted from the light source 10 passes through the wavefront correction system 116 and the scanning system 117 included in the illumination optical system 110 and is irradiated to the eye 20 to be examined. The light reflected or scattered by the fundus 20r of the eye 20 to be examined enters the light receiving optical system 130 including a common optical path with the illumination optical system 110, and passes through the scanning system 117 and the wavefront correction system 116 again. Thereafter, a part of the return light is reflected by the beam splitter 14 provided in the common optical path of the illumination optical system 110 and the light receiving optical system 130 and detected by the wavefront detection system 120. On the other hand, the other part of the return light passes through the beam splitter 14 and is reflected by the polarization beam splitter 13 provided in the common optical path of the illumination optical system 110 and the light receiving optical system 130, and the confocal image detection system 140. The non-confocal image detection system 150 is reached.

  The wavefront correction system 116 corrects the aberration of the return light from the eye 20 based on the information on the wavefront aberration included in the light detected by the wavefront detection system 120. The confocal image detection system 140 and the non-confocal image detection system 150 detect light whose aberration has been corrected. The control unit 160 generates an image of the fundus oculi 20r based on information acquired by the confocal image detection system 140 and the non-confocal image detection system 150. In the fundus imaging apparatus 100, the light receiving optical system 130 that guides the light from the fundus 20r of the eye 20 to the confocal image detection system 140 and the non-confocal image detection system 150 includes a common optical path with the illumination optical system 110. It is a configuration. On the other hand, the light receiving optical system 130 may be configured only by a common optical path with the illumination optical system 110.

  In the fundus imaging apparatus 100 according to the present embodiment, a polarizing plate 60 is provided in the optical path of the non-confocal image detection system 150. The polarizing plate 60 is arranged so that the linearly polarized light component of the transmitted light is orthogonal to the linearly polarized light component in the first polarization direction that is transmitted by the polarizing beam splitter 13 and guided to the λ / 4 plate 19. As a result, the non-confocal image detection system 150 detects and blocks unnecessary light while suppressing the occurrence of errors due to a decrease in the intensity of light detected by the confocal image detection system 140. A 20r image can be acquired with high resolution. The reason for this will be described later in detail with reference to FIGS. 2 (A) and 2 (B).

  Hereinafter, the configuration of the fundus imaging apparatus 100 according to the present embodiment will be described in detail with reference to FIGS.

  The light source 10 is a light source for AO-SLO, which is included in the fundus imaging apparatus 100, and images the fundus 20r with high resolution. The light source 10 emits light having a center wavelength of 800 nm to 850 nm and a half width of about 50 nm. ) Light source. As a light source for AO-SLO, a normal LED (Light Emitting Diode) or LD (Laser Diode) may be used. Further, by using an SLD light source having a wide wavelength band, it is possible to reduce the influence of speckle that appears as noise on an image.

  The illumination optical system 110 includes a collimator lens 12, a polarizing beam splitter 13, a beam splitter 14, a lens 15, a wavefront correction system 116, a scanning system 117, a lens 18, a λ / 4 plate 19, and a λ / 4 plate driving unit 91. It has been.

  The light guided from the light source 10 by the fiber 11 enters the illumination optical system 110, becomes parallel light by the collimator lens 12, and then enters the polarization beam splitter 13.

  The polarization beam splitter 13 transmits linearly polarized light (P-polarized light) that vibrates in the Y-axis direction out of light incident through the collimator lens 12. For example, the polarization beam splitter 13 has a characteristic of transmitting P-polarized light and reflecting linearly-polarized light (S-polarized light) oscillating in the X-axis direction, and the polarization extinction ratio of P-polarized light and S-polarized light is Tp: Ts. Those with characteristics> 100: 1 can be used. In order to reduce the error due to the polarization characteristic, a characteristic having a polarization extinction ratio of P polarization and S polarization of Tp: Ts> 1000: 1 may be used. In the present embodiment, a configuration example in which the linearly polarized light (P-polarized light) component in the first polarization direction transmitted through the polarization beam splitter 13 is guided to the fundus 20r will be described. On the other hand, it is also possible to use a polarization beam splitter having the characteristics of transmitting S-polarized light and reflecting P-polarized light.

  The light transmitted through the polarizing beam splitter 13 enters the beam splitter 14. The beam splitter 14 transmits incident light according to a predetermined transmittance. The light transmitted through the beam splitter 14 is guided to the wavefront correction system 116 via the lens 15. The transmittance of the beam splitter 14 may be arbitrary, but can be set in consideration of the light amount ratio of the detection light in the wavefront detection system 120 to the light from the fundus 20r. For example, the transmittance of the beam splitter 14 may be set so that 10% of the light from the fundus 20r is guided to the wavefront detection system 120.

  The wavefront correction system 116 includes lenses 16 a and 16 b and a wavefront correction device 66. Regarding the arrangement of each optical member, the rear side (image side (left side of the paper)) focal position of the lens 16a is the front focal point (object side (right side of the paper)) of the lens 15, and the front focal position of the lens 16a is that of the lens 16b. They are arranged so as to substantially coincide with the rear focal position. The wavefront correction device 66 is disposed at a position corresponding to the front focal position of the lens 16a and the rear focal position of the lens 16b. The wavefront correction device 66 is arranged at a position conjugate with the eye pupil 20p to correct the wavefront aberration generated in the eye 20 based on information on the wavefront aberration acquired by the wavefront detection system 120 described later. In the present embodiment, the wavefront detection system 120 that detects the aberration generated in the eye 20 and the wavefront correction system 116 that corrects based on the information are collectively referred to as an adaptive optical system.

  Specific examples of the wavefront correction device 66 include LCOS-SLM (Liquid Crystal On Silicon-Spatial Light Modulator) and DM (Deformable Mirror). Since DM can correct aberrations without depending on polarization, aberration correction can be performed with one DM. On the other hand, LCOS uses the birefringence of liquid crystal molecules to control the wavefront by controlling the phase of light, and in order to correct all wavefronts, two LCOSs arranged at right angles are used. -SLM must be used. For this reason, for example, when an LCOS-SLM is used as the wavefront correction device 66, the wavefront correction system 116 that forms a double image is formed, and two LCOS-SLMs are arranged at positions conjugate to the eye pupil 20p. It is preferable to do.

  The light that has passed through the beam splitter 14 and entered the wavefront correction system 116 passes through the wavefront correction system 116 and enters the scanning system 117.

  The scanning system 117 is provided with lenses 17 a and 17 b and a scanning unit 77. The optical members are arranged so that the rear focal position of the lens 17a substantially coincides with the front focal position of the lens 16b and the front focal position of the lens 17a substantially coincides with the rear focal position of the lens 17b. The scanning unit 77 is disposed at a position corresponding to the front focal position of the lens 17a and the rear focal position of the lens 17b.

  For the scanning unit 77, a galvano scanner, a resonant scanner, a polygon mirror, or the like is used. The scanning unit 77 is disposed at a position conjugate with the eye to be examined 20p, and is rotated within a certain angle range under the control of the control unit 160. Thereby, the scanning system 117 guides and irradiates the light from the incident light source 10 to the fundus 20r, and scans within a desired range on the fundus 20r. For example, in the scanning system 117 that forms a double image, the scanning unit 77 includes a scanning unit that performs sub-scanning and a high-speed scanning unit that performs high-speed main scanning compared to the sub-scanning, thereby combining the fundus 20r. The light irradiated thereon can be scanned two-dimensionally. As a specific example of the scanning range by the scanning system 117, a 0.3 mm × 0.3 mm micro area on the fundus 20r, a 1.0 mm × 1.0 mm area wider than the micro area, or 0.3 mm × 1.0 mm. A rectangular region such as

  Further, the scanning system 117 is provided with a drive mechanism 78 that moves the position of the lens 17b in the optical axis direction (Z direction) to adjust the focus. The drive mechanism 78 controls the focus of the lens 17b according to the diopter of the eye 20 based on the detection results of the confocal image detection system 140, the non-confocal image detection system 150, and the wavefront detection system 120. 160. Specifically, the drive mechanism 78 adjusts the focus position of the lens 17b based on the defocus (blur) in the detected image of the eye 20 and the aberration of the defocus component detected by the wavefront sensor. Thereby, the light receiving element 43 of the confocal image detection system 140, the light receiving elements 55a and 55b of the non-confocal image detection system 150, and the fundus 20r can be in a conjugate relationship. The control unit 160 generates an image of the fundus 20r of the subject eye 20 based on the information acquired by the light receiving elements 43, 55a, and 55b. The light receiving element 43 of the confocal image detection system 140 and the light receiving elements 55a and 55b of the non-confocal image detection system 150 are only required to detect the intensity of the return light from the fundus 20r, and need not necessarily be conjugate with the fundus 20r. Absent. The scanning unit 77 and the driving mechanism 78 may be connected to a control unit separate from the control unit 160 and controlled by the control unit.

  The lens 18 is disposed such that the rear focal position substantially coincides with the front focal position of the lens 17b and the front focal position of the lens 18 substantially coincides with the eye pupil 20p to be examined. Thereby, the fundus imaging apparatus 100 is configured such that the wavefront correction device 66, the scanning unit 77, and the eye pupil 20p to be examined have a conjugate positional relationship.

  The λ / 4 plate 19 is disposed between the lens 18 and the eye 20 to be examined. The λ / 4 plate 19 converts linearly polarized light (P-polarized light) that has passed through the polarization beam splitter 13 and vibrates in the Y-axis direction into circularly polarized light. The light converted into circularly polarized light is irradiated to the eye 20 to be examined. The light irradiated to the eye 20 is reflected and scattered by the fundus 20r of the eye 20 and enters the light receiving optical system 130 as return light.

  The light receiving optical system 130 includes a λ / 4 plate 19, a lens 18, a scanning system 117, a wavefront correction system 116, a lens 15, a beam splitter 14, and a polarizing beam splitter 13 as a common optical path with the illumination optical system 110. The light receiving optical system 130 is provided with a mirror 31 and a lens 32 in order to guide the light reflected by the polarization beam splitter 13 to the confocal image detection system 140 and the non-confocal image detection system 150. The light receiving optical system 130 also includes a λ / 4 plate driving unit 91 to which the λ / 4 plate 19 is connected. The return light incident on the light receiving optical system 130 passes through the λ / 4 plate 19 again.

  The return light that has passed through the λ / 4 plate 19 is converted into linearly polarized light (S-polarized light) that vibrates in the X-axis direction, and passes again through the scanning system 117 and the wavefront correction system 116. For this reason, in the fundus imaging apparatus 100 according to the present embodiment, the polarization characteristics of light are different between the forward path from the polarization beam splitter 13 to the eye 20 and the return path from the eye 20 to the polarization beam splitter 13.

  Depending on the characteristics of the eye 20 to be examined, the light incident on the eye 20 to be examined may not be circularly polarized in the fundus 20r. In this case, when the return light from the eye 20 is transmitted through the λ / 4 plate 19, it is not appropriately converted to S-polarized light, and there is a possibility that the polarization characteristics of the return light are disturbed. On the other hand, the λ / 4 plate 19 is connected to a λ / 4 plate driving unit 91 that rotates the λ / 4 plate 19 about the optical axis, and the λ / 4 plate driving unit 91 causes the polarization characteristics to be disturbed. Can be prevented. The λ / 4 plate driving unit 91 performs fine adjustment by rotating the direction of the λ / 4 plate 19 in the direction of rotation about the optical axis, and adjusts the polarization characteristics of light passing through the λ / 4 plate 19. It is controlled by the control unit 160. Therefore, in the fundus imaging apparatus 100, by adjusting the direction (position) of the λ / 4 plate 19 using the λ / 4 plate driving unit 91, the light incident on the eye 20 to be examined is circularly polarized in the fundus 20r. Can do. In this embodiment, the λ / 4 plate driving unit 91 is connected to the control unit 160. However, the λ / 4 plate driving unit 91 is connected to a control unit separate from the control unit 160, and is controlled by the control unit. It may be controlled.

  The λ / 4 plate 19 can be arranged in the vicinity of a position conjugate with the eye pupil 20p to be examined and in the position closest to the eye 20 in the illumination optical system 110. If the position is not conjugate with the eye pupil 20p to be examined, there is a possibility that a phase shift occurs due to the return light incident obliquely on the λ / 4 plate 19 and the polarization characteristics are disturbed. When the λ / 4 plate 19 is disposed at a position away from the eye 20 to be examined, unnecessary light reflected by the optical member disposed between the λ / 4 plate 19 and the eye 20 to be examined is also λ. / 4 It becomes S polarized light through the plate 19. Accordingly, the unnecessary light is also reflected by the polarization beam splitter 13 and detected by the light receiving elements 43, 55a, and 55b. Therefore, detection accuracy may be reduced due to generation of noise caused by the unnecessary light.

  The return light that has passed through the λ / 4 plate 19, the scanning system 117, and the wavefront correction system 116 enters the beam splitter 14 through the lens 15, and a part of the return light is reflected by the beam splitter 14 and the wavefront detection system 120. Led to.

  The wavefront detection system 120 includes a mirror 21, lenses 22a and 22b, a diaphragm 23, a polarizing plate 24, and a wavefront sensor 25. Each optical member is disposed such that the diaphragm 23 has a conjugate positional relationship with the fundus 20r and the wavefront sensor 25 has a conjugate positional relationship with the eye pupil 20p.

  The diaphragm 23 shields reflected light from the cornea and the like of the eye 20 to be examined, which is not necessary for acquiring a fundus image. The polarizing plate 24 transmits S-polarized light from the eye 20 and blocks other unnecessary light. The wavefront sensor 25 includes a microlens array and an image sensor such as a CCD placed on the focal plane thereof. As the wavefront sensor 25, for example, a Hartmann Shack sensor is applicable.

  The return light reflected by the beam splitter 14 and incident on the wavefront detection system 120 is reflected by the mirror 21, passes through the lens 22 a, the diaphragm 23, the lens 22 b, and the polarizing plate 24 and enters the wavefront sensor 25. The wavefront sensor 25 detects the incident return light and acquires information on the wavefront aberration of the eye 20 included in the return light. The adaptive optics system drives the wavefront correction device 66 based on the wavefront aberration information acquired by the wavefront sensor 25 and corrects the wavefront aberration generated in the eye 20 to be examined. In the adaptive optical system, the wavefront correction device 66 may be controlled by a control unit (not shown) based on the information on the wavefront aberration acquired by the wavefront sensor 25, or the wavefront correction device 66 may be similarly controlled by the control unit 160. You may control.

  The return light transmitted through the beam splitter 14 is reflected by the polarization beam splitter 13 and guided to the confocal image detection system 140 and the non-confocal image detection system 150 through the mirror 31 and the lens 32 of the light receiving optical system 130.

  The confocal image detection system 140 is provided with a mirror member 41, a lens 42, and a light receiving element 43. The return light reflected by the polarization beam splitter 13 and the mirror 31 enters the mirror member 41 via the lens 32. Part of the light incident on the mirror member 41 is collected on the reflection surface of the mirror member 41 by the lens 32, and the light reflected by the mirror member 41 is received and detected by the light receiving element 43. In the fundus imaging apparatus 100 according to the present embodiment, the mirror member 41 is provided as a common optical element in the confocal image detection system 140 and the non-confocal image detection system 150.

  The light receiving element 43 generates a confocal signal based on the detected light and sends the confocal signal to the control unit 160. The operation of detecting the light from the fundus 20r by the light receiving element 43 and generating a confocal signal is performed for the range of two-dimensional scanning by the scanning system 117. Thereby, the confocal image detection system 140 captures a confocal image of the fundus 20r. The control unit 160 acquires the intensity distribution of the light detected by the light receiving element 43 from the confocal signal, and generates a confocal image of the fundus 20r based on the intensity distribution. As the light receiving element 43, a photomultiplier tube (PMT), an avalanche photodiode (APD), a photodiode (PD), or the like can be used.

  In the light receiving optical system 130 and the confocal image detection system 140, the optical members are arranged so that the reflection surface of the mirror member 41 and the fundus 20r are conjugate. That is, the lens 32 is arranged such that the front focal position is substantially the same as the rear focal position of the lens 15 and the rear focal position is substantially coincident with the reflecting surface of the mirror member 41.

  FIG. 1B shows an enlarged view of the vicinity of the mirror member 41 of the fundus imaging apparatus 100 shown in FIG. 1A, and FIG. 1C shows a schematic configuration of the mirror member 41 in the XY plane. The mirror member 41 is provided with transmission parts 41a and 41b, a reflection part 41c, and a light shielding part 41d. Of the return light incident on the mirror member 41, the light reflected by the reflecting portion 41c passes through the lens 42 to the light receiving element 43, and the light that passes through the transmitting portions 41a and 41b passes to the non-confocal image detection system 150, respectively. Led.

The outer diameters of the reflection unit 41c and the transmission units 41a and 41b can be set according to the resolutions required by the confocal image detection system 140 and the non-confocal image detection system 150, respectively. For example, the outer diameters of the reflection part 41c and the transmission parts 41a and 41b may be set to about 1 to 2 ADD (Air Disk Diameter) and about 10 to 30 ADD, respectively. Note that ADD means the Airy disk diameter of light, where the Airy disk diameter is D, the wavelength is λ, and the numerical aperture of the light transmitted through the lens 32 is NA, the Airy disk diameter D is obtained from the following equation (1). Calculated.
D = 1.22λ / NA Formula (1)

  The non-confocal image detection system 150 includes a mirror member 41, a lens 51, a polarizing plate 60, a polarizing plate adjustment unit 63, a branching prism 53, lenses 54a and 54b, and light receiving elements 55a and 55b. In the non-confocal image detection system 150, for example, each optical member can be arranged such that the branching prism 53 and the light receiving elements 55a and 55b are conjugated with the mirror member 41, respectively.

  The light transmitted through the mirror member 41 is condensed on the branching prism 53 via the lens 51 and the polarizing plate 60. The light transmitted through the transmission part 41a of the mirror member 41 is reflected by the branching prism 53, and then received and detected by the light receiving element 55a through the lens 54a. The light transmitted through the transmission part 41b is reflected by the branching prism 53 and then received and detected by the light receiving element 55b via the lens 54b. Thereby, in the non-confocal image detection system 150, each of the scattered light and reflected light (return light) from the fundus 20r other than the light detected by the confocal image detection system 140 is divided by the branching prism 53 and thereafter It is detected by the light receiving elements 55a and 55b.

  Each of the light receiving elements 55 a and 55 b generates a non-confocal signal based on the detected light, and sends the non-confocal signal to the control unit 160. An operation of detecting light from the fundus 20r by the light receiving elements 55a and 55b and generating a non-confocal signal is performed for a range of two-dimensional scanning by the scanning system 117. Thereby, the non-confocal image detection system 150 captures a non-confocal image of the fundus 20r. The control unit 160 acquires the intensity distribution of each of the lights detected by the light receiving elements 55a and 55b from the non-confocal signal, and generates a difference image (non-confocal image) of the fundus 20r based on the acquired difference value of the intensity distribution. Generate. For the light receiving elements 55a and 55b, a photomultiplier tube (PMT), an avalanche photodiode (APD), a photodiode (PD), or the like can be used as in the light receiving element 43.

  The polarizing plate 60 is disposed so as to transmit S-polarized light. As a result, in the non-confocal image detection system 150, light having a P-polarized linearly polarized light component that is unnecessary light out of the light that has been reflected by the polarization beam splitter 13 and then transmitted through the mirror member 41 is blocked by the polarizing plate 60. In addition, only light having a linearly polarized component of S-polarized light is transmitted through the polarizing plate 60. For this reason, the light receiving elements 55a and 55b detect only light having a direct polarization component of S polarization.

  The polarizing plate adjustment unit 63 (adjustment unit) has a rotation drive mechanism capable of adjusting the angle (orientation) in the direction in which the polarizing plate 60 is rotated around the optical axis (= Z-axis direction) of the return light. The polarizing plate adjustment unit 63 is connected to the control unit 160, and can rotate and adjust the polarizing plate 60 about the optical axis under the control of the control unit 160. The polarizing plate adjustment unit 63 may be connected to a control unit separate from the control unit 160 that controls the rotation of the polarizing plate 60 and may be controlled by the control unit.

  The control unit 160 is connected to the light receiving element 43 of the confocal image detection system 140 and the light receiving elements 55a and 55b of the non-confocal image detection system 150, and based on signals from these, the confocal image and the non-confocal image are detected. An image (difference image) is generated. The control unit 160 is connected to the display unit 170, and can display the generated image, information about the eye 20 to be examined, and the like on the display unit 170. Further, as described above, the control unit 160 is also connected to the scanning unit 77, the driving mechanism 78, the λ / 4 plate driving unit 91, the polarizing plate adjustment unit 63, and the like, and can control them.

  The control unit 160 may be an arithmetic unit configured inside the fundus imaging apparatus 100 using an MPU, CPU, memory, or the like, or may be an arithmetic apparatus using a general-purpose computer separately from the fundus imaging apparatus 100. . The display unit 170 may be an arbitrary display device provided inside or outside the fundus imaging apparatus 100. Note that the control unit 160 may be connected to an arbitrary interface member and transmit the captured image to the outside, or may be stored in a connected external storage device. Further, the control unit 160 may set an imaging range of the fundus based on an operation through the arbitrary interface member.

The control unit 160 generates a difference image based on the difference in the intensity of light transmitted through the transmission units 41 a and 41 b divided in the mirror member 41. For example, for each pixel of the generated difference image, when the light intensities detected by the light receiving elements 55a and 55b are Ia and Ib and the signal intensity of the difference image is Iab, the signal intensity Iab of the difference image is Is calculated from the equation (2).
Iab = (Ia−Ib) / (Ia + Ib) (2)

  In imaging, the confocal image detection system 140 and the non-confocal image detection system 150 having a deeper depth of field than the confocal image detection system 140 are used to detect light from the fundus 20r substantially simultaneously. can do. For example, the control unit 160 controls the light receiving element 43 of the confocal image detection system 140 and the light receiving elements 55a and 55b of the non-confocal image detection system 150 so as to detect light from the fundus 20r substantially simultaneously. Can be made. Thereby, by performing two-dimensional scanning by the scanning system 117, a confocal image and a difference image (non-confocal image) can be acquired substantially simultaneously.

  Next, the influence of unnecessary light from each surface of the optical member and the eye in the fundus imaging apparatus 100 will be described with reference to FIGS. Hereinafter, the case where the polarizing plate 60 is not provided in the fundus imaging apparatus 100 illustrated in FIG. 1 will be described.

  P-polarized light is dominant in the reflected light from each surface of the optical member in the illumination optical system 110. Furthermore, light (returned light) reflected and scattered by the eye 20 may include light other than S-polarized light. In the polarization beam splitter 13, a part of these P-polarized light is reflected at a lower reflectance than S-polarized light due to the extinction ratio characteristic, and is guided to the confocal image detection system 140 and the non-confocal image detection system 150. It will be scratched. At this time, since the intensity of the light from the fundus 20r is very weak, the influence of unnecessary light cannot be ignored relatively.

  In addition, unnecessary light has a feature that the non-confocal image detection system 150 is more susceptible to influence than the confocal image detection system 140.

  For example, in the mirror member 41, when the area of the reflection part 41c is very small, the intensity of unnecessary light incident on the confocal image detection system 140 is reduced, and the detection accuracy of unnecessary light from the fundus 20r is reduced. The effect on the environment tends to be small.

  On the other hand, in the non-confocal image detection system 150, since the areas of the transmission parts 41a and 41b are larger than those of the reflection part 41c, unnecessary light reaches the light receiving elements 55a and 55b via the lenses 51, 54a and 54b. Cheap. Here, for example, the outer diameters of the transmission parts 41a and 41b are about 10 to 30ADD, and the outer diameter of the reflection part 41c is about 1 to 2ADD.

  Further, in the generation of the difference image using the non-confocal image detection system 150, the difference image is generated from the difference value of the intensity of the light detected through the divided transmission parts 41a and 41b. Therefore, for example, when unnecessary light is incident on one of the divided transmission parts 41a and 41b, the influence of unnecessary light on the difference image is reduced by taking a difference in the intensity distribution of the detected light. It is difficult.

  For this reason, the non-confocal image detection system 150 is more susceptible to noise caused by unnecessary light than the confocal image detection system 140, and the detection accuracy is likely to decrease due to the occurrence of an error.

  Here, a case where a polarizing plate is not used and a case where the polarizing plate is provided between the polarizing beam splitter 13 and the mirror 31 will be described with reference to FIGS. FIG. 2A illustrates a fundus imaging apparatus 200 in which a polarizing plate is not provided as compared with the fundus imaging apparatus 100 illustrated in FIG. 2B is different from the fundus imaging apparatus 100 shown in FIG. 1A in the arrangement of the polarizing plate 360, and the polarizing plate 360 is provided between the polarizing beam splitter 13 and the mirror 31. The fundus imaging apparatus 300 is shown. Note that in the fundus imaging apparatuses 200 and 300 shown in FIGS. 2A and 2B, the same components as those in the fundus imaging apparatus 100 are denoted by the same reference numerals, and description thereof is omitted.

  Since the fundus imaging apparatus 200 illustrated in FIG. 2A has a configuration in which a polarizing plate is not disposed, light including P-polarized light that is unnecessary light is detected by the confocal image detection system 140 and the non-confocal image detection system 150, respectively. Is done. At this time, in the light detected by the confocal image detection system 140, the intensity of the light from the fundus 20r is larger than that of unnecessary light, so that a decrease in detection accuracy due to unnecessary light is limited, which is problematic. It will not be. On the other hand, in the non-confocal image detection system 150, the light from the fundus 20r including unnecessary light is divided using the transmission parts 41a and 41b. Since the difference image is generated from the difference value of the intensity of the divided light, the light detected by the light receiving elements 55a and 55b includes noise due to unnecessary light, and the detection accuracy may be reduced. .

  In contrast, in the fundus imaging apparatus 300 shown in FIG. 2B, a polarizing plate 360 is disposed between the polarizing beam splitter 13 and the mirror 31. The polarizing plate 360 is disposed so that the linearly polarized light component transmitted is orthogonal to the linearly polarized light component of P-polarized light transmitted by the polarizing beam splitter 13. That is, the polarizing plate 360 is disposed so as to transmit the S-polarized light reflected by the polarizing beam splitter 13 and block the P-polarized light that is unnecessary light. At this time, in the non-confocal image detection system 150, since unnecessary light is blocked by the polarizing plate 360, noise caused by unnecessary light is sufficiently small, and light from the fundus 20r can be detected with high accuracy. That is, in the non-confocal image detection system 150, a decrease in the intensity of light from the fundus 20r is not a problem on the principle of generating a difference image, and light can be detected with high accuracy by blocking unnecessary light. .

  On the other hand, in the confocal image detection system 140, the intensity of light from the fundus 20r as well as unnecessary light is reduced by the polarizing plate 360. Therefore, the light source, the compensation optical system for the light from the fundus 20r, electrical noise generated in the light receiving element, etc. The effect of is relatively large. As a result, in the confocal image detection system 140, the S / N ratio of the detected signal is lowered, and the detection accuracy may be lowered.

  As described above, in the fundus imaging apparatuses 200 and 300 shown in FIGS. 2A and 2B, compared to the fundus imaging apparatus 100, both the confocal image detection system 140 and the non-confocal image detection system 150 are used. There is a problem that the fundus 20r of the eye 20 to be examined cannot be imaged with high resolution.

  Subsequently, position adjustment of the polarizing plate 60 in the fundus imaging apparatus 100 according to the present embodiment will be described.

  In the present embodiment, the polarizing plate 60 is disposed in the optical path of the non-confocal image detection system 150. The polarizing plate 60 is arranged so that the linearly polarized light component transmitted through the polarizing plate 60 is orthogonal to the linearly polarized light component of P-polarized light transmitted through the polarizing beam splitter 13 and guided to the λ / 4 plate 19. . As a result, in the non-confocal image detection system 150, light having a P-polarized linearly polarized light component that is unnecessary light out of the light that has been reflected by the polarization beam splitter 13 and then transmitted through the mirror member 41 is blocked by the polarizing plate 60. In addition, only light having a linearly polarized component of S-polarized light is transmitted through the polarizing plate 60. For this reason, the light receiving elements 55a and 55b detect only light having a direct polarization component of S polarization.

  Further, in the confocal image detection system 140, since the polarizing plate 60 is not disposed in the optical path of the return light, the intensity of the light reflected by the mirror member 41 after being reflected by the polarization beam splitter 13 is reduced. Without being detected by the light receiving element 43.

  Therefore, in the fundus imaging apparatus 100 of the present embodiment, the fundus can be imaged with high resolution by both the confocal image detection system 140 and the non-confocal image detection system 150. Further, as described above, the control unit 160 controls the light receiving element 43 of the confocal image detection system 140 and the light receiving elements 55a and 55b of the non-confocal image detection system 150, respectively, so that light from the fundus 20r is substantially simultaneously. Can be operated to detect. In this case, the fundus imaging apparatus 100 can image the fundus with high resolution substantially simultaneously by both the confocal image detection system 140 and the non-confocal image detection system 150.

  As described above, the fundus imaging apparatus 100 according to the present embodiment includes the light source 10 and the illumination optical system 110 that scans the subject eye 20 by irradiating light from the light source 10. In addition, the fundus imaging apparatus 100 includes a confocal image detection system 140 that captures a confocal image of the fundus 20r based on the light from the fundus 20r of the eye 20 to be examined, and the fundus 20r based on the light from the fundus 20r. A non-confocal image detection system 150 that captures a non-confocal image. Further, the fundus imaging apparatus 100 includes a light receiving optical system 130 that includes a common optical path with the illumination optical system 110 and guides light from the fundus 20r to the confocal image detection system 140 and the non-confocal image detection system 150. Further, the fundus imaging apparatus 100 is disposed in the above-described common optical path, transmits light of a linearly polarized component of the first polarization direction out of the light from the light source 10, and is orthogonal to the first polarization direction. A polarization beam splitter 13 is provided that reflects light of a linearly polarized light component having two polarization directions. Furthermore, the fundus imaging apparatus 100 includes a λ / 4 plate 19 disposed between the polarization beam splitter 13 and the eye 20 to be examined in the above-described common optical path. Still further, the fundus imaging apparatus 100 is disposed in the optical path of the non-confocal image detection system 150, and is a linearly polarized light component of the first or second polarization direction guided from the polarization beam splitter 13 to the λ / 4 plate 19. A polarizing plate 60 (polarizing element) that transmits light of a linearly polarized light component orthogonal to is provided.

  Accordingly, it is possible to reduce the detection of unnecessary light in the non-confocal image detection system 150 while avoiding a decrease in the amount of light in the confocal image detection system 140. Therefore, according to the present embodiment, it is possible to provide a fundus imaging apparatus capable of imaging the fundus 20r of the subject with high resolution using both the confocal image detection system 140 and the non-confocal image detection system 150.

  Further, in the fundus imaging apparatus 100, the λ / 4 plate 19 is disposed at a position conjugate with the eye pupil 20p to be examined. As a result, the light from the eye 20 is incident on the λ / 4 plate 19 at an angle, thereby passing through the λ / 4 plate 19 and being guided to the confocal image detection system 140 and the non-confocal image detection system 150. In other words, it is possible to prevent the light polarization characteristics from being disturbed. Further, the λ / 4 plate 19 is between the polarizing beam splitter 13 and the eye 20 to be examined, the closest position from the eye 20 to be examined in the common optical path, that is, closer to the subject eye 20 than other optical members in the common optical path. Placed in position. For this reason, it is possible to prevent the detection accuracy from being lowered due to the generation of noise caused by unnecessary light reflected by the optical member disposed between the λ / 4 plate 19 and the eye 20 to be examined.

  In this embodiment, the fundus imaging apparatus is configured such that the light emitted from the light source 10 and transmitted through the polarization beam splitter 13 is guided to the λ / 4 plate 19 and the light from the fundus 20r is reflected by the polarization beam splitter 13. 100 was constructed. However, the configuration of the fundus imaging apparatus is not limited to this. For example, the imaging device may be configured such that light emitted from the light source 10 and reflected by the polarization beam splitter 13 is guided to the λ / 4 plate 19 and light from the fundus 20r passes through the polarization beam splitter 13. . In this case, the polarizing plate 60 is non-confocal so that the linearly polarized light component transmitted through the polarizing plate 60 is orthogonal to the linearly polarized light component of S-polarized light reflected by the polarizing beam splitter 13 and guided to the λ / 4 plate 19. It is disposed in the optical path of the image detection system 150. Accordingly, the light having the S-polarized linearly polarized light component that is unnecessary light out of the light transmitted through the polarizing beam splitter 13 and then the mirror member 41 is blocked by the polarizing plate 60, and the light having the P-polarized linearly polarized light component. Only passes through the polarizing plate 60 and is detected by the light receiving elements 55a and 55b. The light reflected by the polarization beam splitter 13 and guided to the λ / 4 plate 19 may be P-polarized light, and the light transmitted through the polarizing plate 60 may be S-polarized light.

  The fundus imaging apparatus 100 according to the present embodiment further includes a polarizing plate adjustment unit 63 that adjusts the position in the direction in which the polarizing plate 60 rotates around the optical axis of the light from the fundus 20r of the eye 20 to be examined. The polarizing plate adjustment unit 63 has a rotation drive mechanism capable of rotating and adjusting the polarizing plate 60 about the optical axis (= Z-axis direction), and adjusts the angle of the polarizing plate 60 in the direction of rotation about the optical axis. Can do. Thereby, the linearly polarized light component of the light transmitted through the polarizing plate 60 can be adjusted.

  In this regard, the control unit 160 controls the polarizing plate adjustment unit 63 based on the intensity of light detected by the non-confocal image detection system 150 or the contrast of the signals forming the pixels in the difference image, and the polarizing plate 60. The direction (position) of can be adjusted. Specific adjustment methods include, for example, a method of rotating the polarizing plate 60 to minimize the intensity of unnecessary light appearing in the difference image, a method of maximizing the signal contrast of the fundus 20r in the difference image, For example, a method of maximizing the signal intensity from the fundus 20r. Thereby, in the light immediately after passing through the polarizing plate 60, for example, the ratio of the intensity Is and Ip of S-polarized light and P-polarized light is set to Is: Ip> 10000: 1, so that the fundus oculi is detected by the non-confocal image detection system 150. The light from 20r can be detected with high accuracy.

  Furthermore, the fundus imaging apparatus 100 according to the present embodiment includes a control unit 160 that controls the confocal image detection system 140 and the non-confocal image detection system 150 so as to simultaneously image the fundus 20r of the eye 20 to be examined. Thereby, by performing two-dimensional scanning by the scanning system 117, a confocal image and a difference image (non-confocal image) can be acquired substantially simultaneously.

  In addition, the fundus imaging apparatus 100 further includes an adaptive optical system that corrects the aberration of the eye 20 included in the light from the fundus 20r. Therefore, the fundus imaging apparatus 100 can offset the influence of the aberration of the eye 20 to be examined with respect to the light from the fundus 20r, and can image the fundus 20r with higher accuracy.

  In the above, with respect to the non-confocal image detection system 150 according to the present embodiment shown in FIG. 1, a configuration in which the return light from the eye 20 is divided into two parts that are line-symmetric in the X-axis direction using the branching prism 53. Explained. However, the direction and number in which light is divided in the non-confocal image detection system 150 are not limited to the division direction and number in the fundus imaging apparatus 100 shown in FIG. With respect to the direction and number of light to be split in the non-confocal image detection system 150, any direction or two or more arbitrary directions can be used as long as the mirror member, the branching prism, the lens, and the light receiving element correspond to each other. It is good as a number. For example, the mirror member 41 and the branching prism 53 may be configured to divide the return light from the eye 20 into two regions that are line-symmetric in the Y-axis direction. In addition, a configuration may be used in which a transmission member of the mirror member uses a mirror member that is divided into four equal parts around the optical axis, and detects the light divided into four using a corresponding light receiving element.

  Further, the fundus imaging apparatus may be configured to detect the light transmitted through the mirror member 41 with the confocal image detection system 140 and the reflected light with the non-confocal image detection system 150, respectively.

  In the present embodiment, the polarizing plate 60 is used as a polarizing element that blocks light of a predetermined polarization component of return light. However, the configuration and means for polarizing and separating the return light from the eye 20 to be examined using a polarizing element are not limited to this embodiment. As the polarizing element, in addition to the polarizing plate, a reflecting mirror using a prism or a Brewster angle may be used. Further, for example, instead of the polarizing plate 60, a mirror member having a part of a wire grid polarizer may be used as a polarizing element, and light passing through the wire grid polarizer may be detected by a non-confocal image detection system. .

  Furthermore, in this embodiment, the branching prism 53 is used as a branching member for branching the optical path of the light transmitted through the mirror member 41. However, such a branching member is not limited to the branching prism 53. For example, using a mirror, a part of the light transmitted through the mirror member 41 is reflected and the rest is transmitted, and the light receiving elements 55a and 55b are used. It may be detected.

  In the present embodiment, the configuration of the fundus imaging apparatus using a lens has been described, but the configuration of the fundus imaging apparatus is not limited to this. For example, by adopting a configuration in which a mirror is arranged instead of at least a part of the lens, it is possible to reduce the influence of unnecessary reflected light and scattered light generated on each surface of the lens. Further, as described above, the light receiving element 43 of the confocal image detection system 140 and the light receiving elements 55a and 55b of the non-confocal image detection system 150 are only required to detect the intensity of the return light from the fundus 20r. It need not be conjugate. Therefore, a configuration in which no lens is disposed in front of these light receiving elements 43, 55a, and 55b may be employed.

[Second Embodiment]
With reference to FIG. 3 thru | or 4 (B), the fundus imaging apparatus 101 by 2nd Embodiment which is another structural example is demonstrated. FIG. 3 schematically shows the configuration of the fundus imaging apparatus 101 according to the second embodiment. In the fundus imaging apparatus 101 according to the present embodiment, the configurations of the confocal image detection system 141 and the non-confocal image detection system 151 are different from the components of the fundus imaging apparatus 101 according to the first embodiment. Therefore, in the following, the fundus imaging apparatus 101 according to the present embodiment will be described focusing on differences from the fundus imaging apparatus 100 according to the first embodiment, and the rest of the configuration is the same as that of the fundus imaging apparatus 100. The same reference numerals are used and description thereof is omitted.

  In the fundus imaging apparatus 101 of the present embodiment, a lens 33 having a long focal length is disposed in the confocal image detection system 141 as compared to the fundus imaging apparatus 100 of the first embodiment, and return light having a small numerical aperture is a polarizing plate. 61 is incident.

  Here, when light is incident on the polarizing plate obliquely, the transmittance of the S-polarized light and the P-polarized light in the polarizing plate changes, that is, the transmittance of the polarizing plate has dependency on the incident angle of light. It is generally known. In particular, it is generally known that the transmittance of light to be blocked increases as the incident angle of light on the polarizing plate increases.

  Hereinafter, the difference between the fundus imaging apparatus 101 according to the present embodiment and the fundus imaging apparatus 100 according to the first embodiment will be described with reference to FIGS.

  FIG. 4A shows the relationship between the polarizing plate 60 and the measurement light 70 (return light) in the non-confocal image detection system 150 of the fundus imaging apparatus 100 according to the first embodiment. A cross section P1 and a cross section P2 indicate cross sections in the direction of the optical axis OA of the measurement light 70 before and after the measurement light 70 passes through the polarizing plate 60, and a circle drawn by a dotted line represents a passing range of the measurement light 70. FIG. 4A also shows an example of the linearly polarized light component of S-polarized light that vibrates in the X-axis direction and the linearly polarized light component of P-polarized light that vibrates in the Y-axis direction, which are included in the respective cross sections P1 and P2 of the measuring light 70. Indicated.

  In the fundus imaging apparatus 100, since the light transmitted through the lens 51 is condensed on the branching prism 53 via the polarizing plate 60, the meridional rays 70Yp and 70Ym and the sagittal rays 70Xp and 70Xm in the measurement light 70 are with respect to the optical axis OA. Have a tilt. Thereby, the meridional rays 70Yp and 70Ym and the sagittal rays 70Xp and 70Xm are obliquely incident on the polarizing plate 60 arranged so that the normal direction is parallel to the optical axis OA. For this reason, in the non-confocal image detection system 150 of the fundus imaging apparatus 100, as shown in FIG. 4A, particularly when the numerical aperture of the measurement light 70 is large and the incident angle with respect to the polarizing plate 60 is large, the polarizing plate There is a possibility that P-polarized light, which is unnecessary light, cannot be blocked with high accuracy.

  On the other hand, FIG. 4B shows the relationship between the polarizing plate 61 and the measurement light 71 in the non-confocal image detection system 151 of the fundus imaging apparatus 101. Similarly to FIG. 4A, the cross section P3 and the cross section P4 show the cross section with respect to the optical axis OA of the measurement light 71 before and after the measurement light 71 passes through the polarizing plate 61, and the circle drawn with a dotted line is the circle of the measurement light 71 Represents the passing range. FIG. 4B also shows an example of the linearly polarized light component of S-polarized light that vibrates in the X-axis direction and the linearly polarized light component of P-polarized light that vibrates in the Y-axis direction, which are included in the respective cross sections P3 and P4 of the measurement light 71. Indicated.

  In the fundus imaging apparatus 101, light that has passed through the lens 33 having a long focal length is incident on the polarizing plate 61. Therefore, the numerical aperture of light incident on the polarizing plate 61 is smaller than that of the measurement light 70 of the fundus imaging apparatus 100. That is, the angle formed between the meridional rays 71Yp and 71Ym and the sagittal rays 71Xp and 71Xm in the measurement light 71 and the optical axis OA is reduced. Therefore, in the non-confocal image detection system 151 of the fundus imaging apparatus 101, the incident angle of the measurement light 70 with respect to the polarizing plate 61 is smaller than that in the non-confocal image detection system 150 of the fundus imaging apparatus 100. Accordingly, in the fundus imaging apparatus 101, an increase in the transmittance of unnecessary light in the polarizing plate 61 is suppressed, and unnecessary light can be accurately blocked by the polarizing plate 61 as shown in FIG.

  In the fundus imaging apparatus 101 according to this embodiment, the non-confocal image detection system 151 adjusts the direction of the polarizing plate 61 so that the intensity of the light from the fundus 20r with respect to unnecessary light is maximized, so that the fundus 20r Can be detected with higher accuracy.

  Note that the non-confocal image detection system 151 of the present embodiment has a configuration in which no lens is disposed between the mirror member 41 and the branching prism 53, and thus the non-confocal image detection system 150 according to the first embodiment and In contrast, the mirror member 41 and the branching prism 53 are not conjugated. For this reason, for example, in the case where the mirror member 41 and the fundus 20r are in a conjugate relationship, the splitting prism 53 divides the light at a position that is not conjugate with the fundus 20r, so that a difference image cannot be generated with high accuracy. There is sex. In that case, a lens may be disposed between the polarizing plate 61 and the branching prism 53 so that the mirror member 41 and the branching prism 53 are in a conjugate relationship.

  As described above, in the fundus imaging apparatus 101 according to the present embodiment, the lens 33 having a long focal length is disposed in the confocal image detection system 141 as compared with the fundus imaging apparatus 100 according to the first embodiment, and light having a small numerical aperture. Enters the polarizing plate 61. Thereby, the measurement light 71 from the fundus 20r of the eye 20 to be examined can enter the polarizing plate 61 substantially parallel to the optical axis OA of the measurement light 71. Therefore, in the fundus imaging apparatus 101 according to the present embodiment, unnecessary light transmitted through the polarizing plate 61 can be accurately blocked as compared with the fundus imaging apparatus 100 according to the first embodiment, and a non-confocal image associated with the unnecessary light can be obtained. A decrease in detection accuracy in the detection system 151 can be suppressed.

[Third Embodiment]
With reference to FIG. 5 thru | or FIG. 6B, the fundus imaging apparatus 102 by 3rd Embodiment which is another structural example is demonstrated. FIG. 5 schematically illustrates the configuration of the fundus imaging apparatus 102 according to the third embodiment. In the fundus imaging apparatus 102 according to the present embodiment, the configuration of the non-confocal image detection system 152 is different from the components of the fundus imaging apparatus 101 according to the first embodiment. Therefore, in the following, the fundus imaging apparatus 102 according to the present embodiment will be described focusing on differences from the fundus imaging apparatus 100 according to the first embodiment, and the rest of the configuration is the same as that of the fundus imaging apparatus 100. The same reference numerals are used and description thereof is omitted.

  The fundus imaging apparatus 102 of the present embodiment is different from the fundus imaging apparatus 100 according to the first embodiment in that the light incident on the polarizing plate 62 is parallel light. The non-confocal image detection system 152 according to the present embodiment includes lenses 52a and 52b, a polarizing plate 62, a branching prism 53, lenses 54a and 54b, and light receiving elements 55a and 55b. Each optical member in the non-confocal image detection system 152 is such that the branching prism 53 and the light receiving elements 55a and 55b are conjugated with the mirror member 41, and the polarizing plate 62 is conjugated with the eye pupil 20p. Placed in. That is, the front focal position of the lens 52a is the rear focal position of the lens 32, the rear focal position of the lens 52a is the front focal position of the lens 52b, and the rear focal position of the lens 52b is the front focal position of the lenses 54a and 54b. Are arranged so as to substantially match. The mirror member 41 is disposed at the front focal position of the lens 52a, the polarizing plate 62 is disposed at the rear focal position of the lens 52a, and the branching prism 53 is disposed at the rear focal position of the lens 52b.

  The measurement light (return light) that has passed through the mirror member 41 is converted into parallel light by passing through the lens 52 a and enters the polarizing plate 62. Therefore, the incident angle of the measurement light with respect to the polarizing plate 62 can be set to approximately 0 °, and an increase in the transmittance of the unnecessary light according to the incident angle in the polarizing plate 62 can be suppressed, and unnecessary light can be blocked with high accuracy. it can. The measurement light transmitted through the polarizing plate 62 is incident on the branching prism 53 via the lens 52b.

  Hereinafter, differences between the fundus imaging apparatus 102 of the present embodiment and the fundus imaging apparatus 100 of the first embodiment will be described with reference to FIGS. 6 (A) and (B). Note that FIG. 6A is similar to FIG. 4A, so description thereof is omitted and FIG. 6B is described in detail.

  FIG. 6B shows the relationship between the polarizing plate 62 and the measurement light 72 in the non-confocal image detection system 152 of the fundus imaging apparatus 102. Similarly to FIG. 6A, the cross section P5 and the cross section P6 show the cross section with respect to the optical axis OA of the measurement light 72 before and after the measurement light 72 passes through the polarizing plate 62, and the circle drawn with a dotted line is the circle of the measurement light 72 Represents the passing range. FIG. 6B also shows an example of the linearly polarized light component of S-polarized light that vibrates in the X-axis direction and the linearly polarized light component of P-polarized light that vibrates in the Y-axis direction, which are included in the respective cross sections P5 and P6 of the measuring light 72. Indicated.

  In the fundus imaging apparatus 102, the measurement light 72 converted into parallel light by the lens 52a is incident on the polarizing plate 62. Therefore, the meridional rays 72Yp and 72Ym and the sagittal rays 72Xp and 72Xm in the measurement light 72 are parallel to the optical axis OA. For this reason, in the non-confocal image detection system 152 of the fundus imaging apparatus 102, the transmittance of the unnecessary light according to the incident angle is changed in the polarizing plate 62 as compared with the non-confocal image detection system 150 of the fundus imaging apparatus 100. Does not occur. Accordingly, in the fundus imaging apparatus 102, unnecessary light can be blocked with high accuracy by the polarizing plate 62 as shown in FIG. 6B.

  In the fundus imaging apparatus 102 according to the present embodiment, the polarizing plate 62 disposed in the non-confocal image detection system 152 as described above is disposed so as to be a conjugate position with the eye pupil 20p to be examined. Therefore, the light from the eye 20 is incident on substantially the same portion of the polarizing plate 62 regardless of the angle of view.

  On the other hand, when the polarizing plate 62 is arranged at a position that is not conjugate with the eye pupil 20p, the light from the eye 20 that is away from the optical axis OA that is not parallel by the lens 52 depends on the angle of view. Then, the light is incident on different positions in the plane of the polarizing plate 62. Here, when there is a characteristic difference due to a manufacturing error at each position in the plane of the polarizing plate 62, a difference occurs in the transmittance of unnecessary light according to the position in the plane of the polarizing plate 62. For this reason, when the polarizing plate 62 is disposed at a position that is not conjugate with the eye pupil 20p, unnecessary light that enters the polarizing plate 62 is transmitted with different transmittances depending on the angle of view. As a result, intensity variations occur in the plane of the spot light detected by the light receiving elements 55a and 55b of the non-confocal image detection system 152. Therefore, in this case, the detection accuracy by the light receiving elements 55a and 55b is lowered.

  However, in the fundus imaging apparatus 102 according to the present embodiment, since the polarizing plate 62 is disposed at a position conjugate with the eye pupil 20p to be examined as described above, the incident light on the polarizing plate 62 is within the plane of the polarizing plate 62. It is incident on substantially the same part. For this reason, it is possible to suppress a difference in the transmittance of unnecessary light as described above, and to suppress a decrease in detection accuracy by the light receiving elements 55a and 55b.

  As described above, the fundus imaging apparatus 102 according to the present embodiment is configured such that the measurement light 72 enters the polarizing plate 62 as parallel light. Therefore, in the fundus imaging apparatus 102 according to the present embodiment, compared to the fundus imaging apparatus 100, the polarizing plate 62 does not change the transmittance of unnecessary light according to the incident angle. Thereby, in the fundus imaging apparatus 102, the polarizing plate 62 can block unnecessary light with high accuracy, and can detect light from the fundus 20r with higher accuracy.

  In the fundus imaging apparatus 102 according to the present embodiment, the polarizing plate 62 is disposed at a position conjugate with the eye pupil 20p in the non-confocal image detection system 152. Accordingly, it is possible to suppress a decrease in detection accuracy in the non-confocal image detection system 152 due to a difference in the transmittance of unnecessary light in the plane of the polarizing plate 62 based on a manufacturing error of the polarizing plate 62.

  In the fundus imaging apparatus 102 according to the present embodiment as well, the non-confocal image detection system 152 adjusts the orientation of the polarizing plate 62 so that the intensity of light from the fundus 20r with respect to unnecessary light is maximized. Can be detected with higher accuracy.

  Although the present invention has been described with reference to the first to third embodiments, the present invention is not limited to the above embodiments. Inventions modified within the scope not departing from the spirit of the present invention and inventions equivalent to the present invention are also included in the present invention. Moreover, each above-mentioned embodiment and modification can be combined suitably in the range which is not contrary to the meaning of this invention.

10: light source, 13: polarizing beam splitter, 19: λ / 4 plate, 20: eye to be examined, 20r: fundus, 60: polarizing plate (polarizing element), 100: fundus imaging device, 110: illumination optical system, 130: light reception Optical system 140: Confocal image detection system 150: Non-confocal image detection system

Claims (9)

A light source;
An illumination optical system that irradiates and scans the eye to be examined with light from the light source;
A confocal image detection system that captures a confocal image of the fundus based on light from the fundus of the eye to be examined;
A non-confocal image detection system that captures a non-confocal image of the fundus based on light from the fundus;
A light receiving optical system that includes a common optical path with the illumination optical system and guides light from the fundus to the confocal image detection system and the non-confocal image detection system;
Arranged in the common optical path of the illumination optical system and the light-receiving optical system, transmits light of a linearly polarized component of the first polarization direction out of the light from the light source, and is orthogonal to the first polarization direction. A polarizing beam splitter that reflects light of a linearly polarized component in the second polarization direction;
In the common optical path, a λ / 4 plate disposed between the polarization beam splitter and the eye to be examined;
Light of a linearly polarized light component that is arranged in the optical path of the non-confocal image detection system and is orthogonal to the light of the linearly polarized light component in the first or second polarization direction guided from the polarizing beam splitter to the λ / 4 plate. A polarizing element that transmits
A fundus imaging apparatus comprising:   The fundus imaging apparatus according to claim 1, wherein light from the fundus is incident on the polarizing element substantially parallel to an optical axis of the light.   The fundus imaging apparatus according to claim 1, wherein the polarizing element is disposed at a position conjugate with a pupil of the eye to be examined.   The fundus imaging apparatus according to any one of claims 1 to 3, wherein the λ / 4 plate is disposed at a position conjugate with a pupil of the eye to be examined.   5. The λ / 4 plate is disposed between the polarizing beam splitter and the eye to be examined at a position closer to the eye to be examined than other optical members in the common optical path. The fundus imaging apparatus according to one item.   The fundus imaging apparatus according to any one of claims 1 to 5, further comprising an adjustment unit that rotates the polarizing element about an optical axis of light from the fundus to adjust the direction of the polarizing element.   The fundus imaging apparatus according to claim 6, further comprising a control unit that controls the adjustment unit based on a light intensity detected by the non-confocal image detection system or a signal contrast.   The apparatus further comprises a control unit that controls the confocal image detection system and the non-confocal image detection system so that the fundus is simultaneously imaged by the confocal image detection system and the non-confocal image detection system. The fundus imaging apparatus according to any one of claims 1 to 7.   The fundus imaging apparatus according to any one of claims 1 to 8, further comprising an adaptive optical system that corrects an aberration of the eye to be examined included in light from the fundus.

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