JP6193617B2 - Scanning laser ophthalmoscope - Google Patents

Description

  The present invention relates to a scanning laser ophthalmoscope used for fundus photography.

  A scanning laser opthalmoscope is a device that forms a front image of the fundus by scanning the fundus with laser light and detecting the return light with a light receiving device.

  In measurement using a scanning laser ophthalmoscope, the return light from the eye to be examined includes not only return light from the fundus that contributes to imaging but also return light from the anterior segment such as corneal reflection light. ing. The return light from the anterior eye part may appear as ghost light in the formed image, which hinders observation of the relevant part of the fundus. Similarly, reflected light from an optical element (such as a lens) included in the apparatus optical system may cause the same problem. The following measures have been taken for this problem.

  As a first countermeasure, laser light is incident on the eye to be examined from a position off the axis of the eye to be examined (that is, a position outside the vertex of the cornea or the center of the pupil). There is a method to prevent the incidence. However, application of this method requires a condition that the pupil diameter of the eye to be examined is large. Therefore, new problems arise, such as having to administer a mydriatic agent, which is a burden on the subject, and making it difficult to align the apparatus optical system with the eye to be examined.

  As a second countermeasure, there is a method of blocking the return light from the anterior segment by using a confocal stop having a sufficiently small aperture. However, when the confocal stop is used, part of the return light from the fundus is also blocked, and the light receiving efficiency is lowered. Therefore, the confocal stop is often not used in the measurement by the scanning laser ophthalmoscope. For example, as described in Patent Document 2, it is usual to use a light-receiving stop having an opening that is at least four times the diameter of a laser beam spot formed on the fundus. It should be noted that ghost light cannot be sufficiently suppressed with a light receiving stop having such an aperture size.

  As a third countermeasure, there is a method of irradiating a subject's eye with linearly polarized laser light and selectively detecting a polarization component orthogonal thereto. When linearly polarized laser light is used in this way, the brightness of the image becomes uneven due to the polarization characteristics of the fundus, resulting in a problem that the image quality deteriorates.

Japanese Patent No. 4774261 U.S. Pat. No. 7,703,922

  An object of the present invention is to provide a scanning laser ophthalmoscope capable of removing ghost light without problems such as a burden on a subject and a reduction in image quality.

The invention according to claim 1 is based on an optical system that scans the fundus by irradiating the eye to be examined with laser light and detects return light of the laser light from the eye to be examined, and a detection result of the return light. A scanning laser ophthalmoscope having an image forming unit for forming a front image of the fundus, wherein the optical system is substantially different from the return light from the anterior eye portion of the return light from the fundus of the laser light An optical element group that selectively transmits a polarization component; and a light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal, and the image forming unit is output from the light receiving element. The front image is formed based on the electrical signal, and the optical system irradiates the eye to be examined with circularly polarized laser light output from a light source and having a first rotation direction with respect to the traveling direction. The group consists of the circularly polarized laser light to be examined. Among the return light, a polarization component selection element that selectively passes a linearly polarized component in a first direction corresponding to the first rotation direction, and the polarization component selection element is included in the return light from the eye to be examined The circularly polarized light component in the first rotational direction is converted into the linearly polarized light component in the first direction, and the circularly polarized light component in the second rotational direction opposite to the first rotational direction is orthogonal to the first direction. A wave plate for converting into a linearly polarized light component in the second direction, and a linearly polarized light component in the first direction out of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the wave plate. And a polarizer that allows the light to pass selectively .
The invention according to claim 2 is based on an optical system that scans the fundus by irradiating the eye to be examined with laser light and detects return light of the laser light from the eye to be examined, and a detection result of the return light. A scanning laser ophthalmoscope having an image forming unit for forming a front image of the fundus, wherein the optical system is substantially different from the return light from the anterior eye portion of the return light from the fundus of the laser light An optical element group that selectively transmits a polarization component; and a light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal, and the image forming unit is output from the light receiving element. the front image is formed based on the electrical signal, the optical element group, and the polarization characteristic conversion element for converting the polarization characteristic of the laser light output from the light source to the radial polarization, the subject's eye of the laser light of the radial polarization Return light from Characterized in that it comprises a polarization component selection element for selectively passing the Chi azimuthal polarization component.
The invention of claim 3 is a scanning laser ophthalmoscope according to claim 2, wherein the polarization characteristics conversion element that converts the polarization characteristic of the laser light output from the light source to direct linearly polarized light a polarizer, a polarization characteristic before the laser light passing through the Kihen photons before and a first polarization control element that converts the radial polarization from Kijika line polarization, the polarization component selection element returns from the subject's eye A second polarization control element that selectively passes an azimuth polarization component of the light is included.
The invention according to claim 4 is based on an optical system that scans the fundus by irradiating the eye to be examined with laser light and detects return light of the laser light from the eye to be examined, and a detection result of the return light. A scanning laser ophthalmoscope having an image forming unit for forming a front image of the fundus, wherein the optical system is substantially different from the return light from the anterior eye portion of the return light from the fundus of the laser light An optical element group that selectively transmits a polarization component; and a light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal, and the image forming unit is output from the light receiving element. The optical element group forms a front image based on the electrical signal, and the optical element group includes a polarization characteristic conversion element that converts a polarization characteristic of the laser light output from the light source into azimuth polarization, and an eye to be inspected of the azimuth polarization laser light. Return light from Characterized in that it comprises a polarization component selection element for selectively passing the Chi radial polarization component.
A fifth aspect of the present invention is the scanning laser ophthalmoscope according to the fourth aspect, wherein the polarization characteristic conversion element converts a polarization characteristic of laser light output from the light source into linearly polarized light. And a first polarization control element that converts the polarization characteristics of the laser light that has passed through the polarizer from the linearly polarized light to the azimuth polarized light, and the polarization component selecting element is a radial polarization of the return light from the eye to be examined. A second polarization control element that selectively allows the component to pass therethrough is included .
The invention according to claim 6 is based on an optical system that scans the fundus by irradiating the eye to be examined with laser light and detects return light of the laser light from the eye to be examined, and a detection result of the return light. A scanning laser ophthalmoscope having an image forming unit for forming a front image of the fundus, wherein the optical system is substantially different from the return light from the anterior eye portion of the return light from the fundus of the laser light An optical element group that selectively transmits a polarization component; and a light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal, and the image forming unit is output from the light receiving element. the front image is formed based on the electrical signal, the optical element group, and the polarization characteristic conversion element for converting the polarization characteristic of the laser beam straight line polarized light output from the light source into radially polarized light, the laser of the radial polarization From the light eye And characterized in that the azimuthal polarized component of the return light selectively passes and a polarization component selected element.
The invention according to claim 7 is based on an optical system that scans the fundus by irradiating the eye to be examined with laser light and detects return light of the laser light from the eye to be examined, and a detection result of the return light. A scanning laser ophthalmoscope having an image forming unit for forming a front image of the fundus, wherein the optical system is substantially different from the return light from the anterior eye portion of the return light from the fundus of the laser light An optical element group that selectively transmits a polarization component; and a light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal, and the image forming unit is output from the light receiving element. The front image is formed on the basis of the electrical signal, and the optical element group includes a polarization characteristic conversion element that converts a polarization characteristic of the linearly polarized laser light output from the light source into azimuth polarized light, and the azimuth polarized laser light. From the eye to be examined And characterized in that the radially polarized light component of the return light selectively passes and a polarization component selected element.
The invention according to claim 8 is based on an optical system that scans the fundus by irradiating the eye to be examined with laser light and detects return light of the laser light from the eye to be examined, and a detection result of the return light. A scanning laser ophthalmoscope having an image forming unit for forming a front image of the fundus, wherein the optical system is substantially different from the return light from the anterior eye portion of the return light from the fundus of the laser light An optical element group that selectively transmits a polarization component; and a light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal, and the image forming unit is output from the light receiving element. The front image is formed based on the electrical signal, the optical system irradiates the subject's eye with the radially polarized laser light output from the light source, and the optical element group is the subject eye of the radially polarized laser beam. Aji out of the return light from Characterized in that it comprises a polarization component selection element for selectively passing scan polarization component.
The invention according to claim 9 is based on an optical system that scans the fundus by irradiating the eye to be examined with laser light and detects the return light of the laser light from the eye to be examined, and the detection result of the return light. A scanning laser ophthalmoscope having an image forming unit for forming a front image of the fundus, wherein the optical system is substantially different from the return light from the anterior eye portion of the return light from the fundus of the laser light An optical element group that selectively transmits a polarization component; and a light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal, and the image forming unit is output from the light receiving element. The front image is formed based on the electrical signal, the optical system irradiates the eye to be examined with azimuth-polarized laser light output from a light source, and the optical element group is the eye to be examined for the azimuth-polarized laser light. Raj out of the return light from the Characterized in that it comprises a polarization component selection element for selectively passing Le polarization component.

  According to the scanning laser ophthalmoscope according to the present invention, it is possible to remove ghost light without problems such as a burden on the subject and a decrease in image quality.

2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the optical scan by the scanning laser ophthalmoscope which concerns on embodiment is shown. 2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. 2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. 2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. 2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. 2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. 2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. 2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. 2 shows an example of the configuration of a scanning laser ophthalmoscope according to an embodiment. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown. The example of the change of the polarization state in the scanning laser ophthalmoscope which concerns on embodiment is shown.

  The scanning laser ophthalmoscope according to the embodiment will be described in detail with reference to the drawings.

<Constitution>
A configuration example of the scanning laser ophthalmoscope according to the embodiment is shown in FIG. The scanning laser ophthalmoscope 1 forms a front image of the fundus oculi Ef by scanning the fundus oculi Ef of the eye E with a laser beam and detecting the return light with a light receiving device. The scanning laser ophthalmoscope 1 has an optical system and a processing system. The optical system performs optical measurement of the fundus oculi Ef. The optical system includes various optical elements and optical devices. The processing system performs processing of data acquired by the optical system, control of each part of the apparatus, and the like. The processing system includes an arithmetic device, a control device, a storage device (RAM, ROM, hard disk drive, etc.), a user interface, a communication interface, and the like.

(Optical system)
The light source unit 10 is provided with a light source 11, a collimating lens 12, and an optical element 13. As the light source 11, a light source that outputs laser light L0 with high spatial coherency is used. Examples of such a light source include a semiconductor laser light source (wavelength sweep laser, super luminescence and diode, etc.), a solid-state laser, and a gas laser. Moreover, it is also possible to use as the light source 11 what combined the light output from such a light source with the optical fiber, or a fiber laser. The collimating lens 12 turns the laser beam L0 output from the light source 11 into a parallel light beam.

  The optical element 13 includes one or more optical elements having various functions. Examples include polarization control elements such as wave plates and polarizers, light beam limiting elements such as apertures (apertures), and wavelength limiting elements such as wavelength selection filters. The optical element 13 may be a composite element in which the same or different optical elements are combined. Moreover, it is good also as a structure which can apply the some optical element 13 selectively. A configuration example of the optical element 13 will be described later.

  The laser beam L0 converted into a parallel light beam by the collimator lens 12 is guided to the beam splitter 30 via the optical element 13. The component (also referred to as laser beam L0) that has passed through the beam splitter 30 in the laser beam L0 is guided to the optical scanner 40. The optical scanner 40 of the embodiment is assumed to be a biaxial optical scanner. That is, the optical scanner 40 has a configuration capable of two-dimensionally deflecting the laser light L0.

  The laser light L output from the optical scanner 40 is collimated light deflected two-dimensionally. The collimated laser light L is focused by the relay lens 50, and is imaged in the air on a plane (fundus conjugate plane) Pc conjugate with the fundus oculi Ef. Further, the laser light L passes through the objective lens 60 as a focusing lens and enters the eye E. A polarization control element such as a quarter-wave plate may be inserted between the objective lens 60 and the eye E to be examined.

  A part of the laser light L incident on the eye E is scattered by the anterior segment of the eye E. The other part of the laser light L passes through the pupil at the center of the iris Ei, passes through the crystalline lens Ec, and forms an image on the fundus oculi Ef as spot light. The objective lens 60 and the lens barrel 61 are provided so as to be movable in the axial direction (that is, in the optical axis direction). The objective lens 60 and the lens barrel 61 are moved in the optical axis direction according to the refractive power of the eye E. Thereby, the fundus conjugate surface Pc is arranged at a position conjugate with the fundus Ef. As a result, the laser light L forms a clear spot light on the fundus oculi Ef.

  The return light of the laser light L irradiated to the fundus oculi Ef (sometimes referred to as fundus return light) is light that returns to the scanning laser ophthalmoscope 1 from the spot light formation position (and its vicinity). The fundus return light includes scattered light (reflected light and backscattered light) of the laser light L from the fundus oculi E, fluorescence using the laser light L as excitation light, and scattered light thereof. The fundus return light passes through the crystalline lens Ec, passes through the pupil, and exits from the eye E.

  On the other hand, as described above, a part of the laser light L incident on the eye E is scattered by the anterior eye part. The scattered light (anterior segment scattered light) includes corneal reflection light and the like. At least a part of the anterior ocular segment scattered light returns to the scanning laser ophthalmoscope 1 together with the fundus return light. Of the anterior segment scattered light, the light returning to the scanning laser ophthalmoscope 1 may be referred to as anterior segment return light. Due to the configuration of this optical system such as a light flux limiting element 73 of the light receiving unit 70 described later, most of the anterior ocular segment return light reaching the light receiving element 74 is specularly reflected light by the cornea. Hereinafter, the fundus return light and the anterior ocular segment return light may be collectively referred to as return light (from the eye E). This return light is indicated by reference numeral RL.

  The return light RL from the eye E passes through the objective lens 60, forms an aerial image on the fundus conjugate plane Pc, is converted into a parallel light beam by the relay lens 50, and is guided to the beam splitter 30 via the optical scanner 40. . A component of the return light RL reflected by the beam splitter 30 (also referred to as return light RL) is guided to the light receiving unit 70.

  The return light RL guided to the light receiving unit 70 includes reflected light of the laser light L0 from the optical element (lens) inside the optical scanner 40, reflected light of the laser light L from the relay lens 50 or the objective lens 60, and the like. May be mixed.

  The light receiving unit 70 includes an optical element 71, a condenser lens 72, a light beam limiting element 73, and a light receiving element 74.

  The optical element 71 includes one or more optical elements having various functions. Examples include polarization control elements such as wave plates and polarizers, light beam limiting elements such as apertures (apertures), and wavelength limiting elements such as wavelength selection filters. The optical element 71 may be a composite element in which the same or different optical elements are combined. Moreover, it is good also as a structure which can apply the some optical element 71 selectively. A configuration example of the optical element 71 will be described later.

  The return light RL that has passed through the optical element 71 is focused by the condenser lens 72 and guided to the light flux limiting element 73. The light flux restricting element 73 is provided with a light blocking area for blocking light and an opening (light transmitting area) for allowing light to pass through. The opening is, for example, a circular opening, an elliptical opening, or a donut opening. One or more arbitrary numbers of openings are provided. When a plurality of openings are provided, these openings are alternatively arranged with respect to the optical path of the return light RL.

  The return light RL (part of it) that has passed through the opening of the light flux limiting element 73 is detected by the light receiving element 74. The light receiving element 74 photoelectrically converts the detected return light RL and outputs an electric signal (light receiving signal). The light receiving element 74 is, for example, an avalanche photodiode.

  The above process corresponds to measurement of one point of the fundus oculi Ef. That is, the above process corresponds to the measurement of the irradiation area SL of the single spot light shown in FIG. The spot light irradiation area SL is moved by two-dimensional scanning by the optical scanner 40. Reference sign STi (i = 1 to N) in FIG. 2 indicates an example of the movement pattern of the irradiation region SL. In this example, the spot light irradiation area SL is moved along a plurality of parallel trajectories parallel to each other in the same direction. Note that the movement pattern of the irradiation region SL is not limited to this. Examples of other movement patterns include a plurality of linear trajectories that are alternately opposite to each other and parallel to each other, a plurality of non-parallel linear trajectories, and a curved trajectory. The light receiving element 74 detects the return light RL from each irradiation region SL and outputs a light reception signal. Thereby, measurement at a plurality of positions of the fundus oculi Ef is sequentially performed.

  In FIG. 2, the symbol Ef1 indicates the optic disc, the symbol Ef2 indicates the macula, and the symbol Ef3 indicates the blood vessel.

  In the above configuration, for simplicity, the laser light L0 output from the light source unit 10 is limited to one type, but the light source unit 10 may be configured to be capable of outputting a plurality of types of light. For example, it is possible to apply a configuration in which a plurality of light sources having different output wavelengths and collimating lenses corresponding to the respective light sources are provided, and an optical member (such as a dichroic mirror) that joins these optical paths is provided. In addition, the light receiving unit 70 can also be applied with a configuration in which an optical member (such as a dichroic mirror) that divides the optical path from the beam splitter 30 into a plurality of parts and a condensing lens and a light receiving element are arranged in each of these optical paths It is.

(Processing system)
The processing system includes a control unit 100, a power supply unit 110, a light source control unit 120, an image forming unit 130, a data processing unit 140, and a user interface (UI) 150.

(Control unit 100)
The processing system is configured around the control unit 100. The control unit 100 controls each part of the apparatus. The control unit 100 includes a microprocessor and a storage device. The storage device stores in advance a computer program for controlling the scanning laser ophthalmoscope 1. This computer program includes a light source control program, an optical scanner control program, a power supply control program, a general control program, and the like. When the microprocessor operates according to such a computer program, the control unit 100 executes control processing.

  As control for the optical system, control of the light source 11 via the light source control unit 120, selection of the optical element 13 (71) when a plurality of optical elements 13 (71) are provided, control of the optical scanner 40, objective lens 60, movement of the lens barrel 61, switching of the aperture of the light beam limiting element 73, operation control of the light receiving element 74, and the like. As control for the processing system, there is operation control of each part.

  When optical measurement of the fundus oculi Ef is being performed or after the optical measurement is completed, the control unit 100 generates a pixel position signal and sends it to the image forming unit 130. The pixel position signal is obtained by changing the arrangement of the plurality of spot light irradiation areas SL based on the optical scanner control program (that is, changing the light deflection pattern of the optical scanner 40 or the direction of the light reflecting surface of the mirror scanner of the optical scanner 40). The arrangement of a plurality of pixels corresponding to (flow) is shown.

(Power supply unit 110)
The power supply unit 110 supplies power to each unit of the scanning laser ophthalmoscope 1 based on power input from a commercial power supply, a private power generation facility, a battery, or the like. The control unit 100 switches the power supply mode by controlling the power supply unit 110. Examples of the power supply mode include a normal mode, a power saving mode, and a sleep mode.

(Light source control unit 120)
The light source control unit 120 controls the light source 11 under the control of the control unit 100. The light source 11 is controlled, for example, by controlling power supplied from the power supply unit 110. When a plurality of light sources are provided, the light source control unit 120 selectively supplies power to the plurality of light sources under the control of the control unit 100. Thereby, a plurality of light sources are selectively used. The light source control unit 120 includes, for example, a microprocessor and a storage device. Further, the light source control unit 120 may be configured to include dedicated hardware.

(Image forming unit 130)
The image forming unit 130 forms image data based on the light reception signal input from the light receiving element 74 and the pixel position signal input from the control unit 100. This image data corresponds to a front image of the fundus oculi Ef.

  The image forming unit 130 includes, for example, a microprocessor and a storage device. The storage device stores an image forming program in advance. When the microprocessor operates according to the image forming program, at least a part of the image forming process is executed. Further, the light source control unit 120 may be configured to include dedicated hardware.

  The image forming unit 130 includes an A / D conversion unit 131, a fundus image forming unit 132, and a memory unit 133. The A / D converter 131 converts the light reception signal (analog signal) input from the light receiving element 74 into a digital signal.

  The fundus image forming unit 132 forms image data of a front image of the fundus oculi Ef based on the digital signal input from the A / D conversion unit 131 and the pixel position signal input from the control unit 100. This image data forming process includes a process of associating information (pixel value such as luminance) based on a digital signal corresponding to each irradiation position SL of the spot light and a pixel position corresponding to the irradiation position SL.

  The memory unit 133 functions as an internal memory of the image forming unit 130 and temporarily stores the image data formed by the fundus image forming unit 132. The application of the memory unit 133 is arbitrary. The image data formed by the image forming unit 130 is sent to the control unit 100.

(Data processing unit 140)
The data processing unit 140 executes various data processing. As an example of data processing, there is processing for image data formed by the image forming unit 130 or another device. Examples of this processing include various types of image processing and diagnostic support processing such as image evaluation based on image data.

  The data processing unit 140 may be a part of the scanning laser ophthalmoscope 1 or an external device. In the former case, the data processing unit 140 includes, for example, a microprocessor and a storage device. The storage device stores one or more data processing programs in advance. Data processing is executed by the microprocessor operating according to the data processing program. Further, the data processing unit 140 may be configured to include dedicated hardware.

  In the latter case, the data processing unit 140 includes a computer. Examples of the computer include a personal computer, a smartphone, a tablet terminal, a personal digital assistant (PDA), and a server. The control unit 100 has an interface for communicating with the computer. When the computer has a display function, the data processing unit 140 as an external device executes display processing based on information transmitted from the control unit 100. Examples of the display processing target include an image based on image data, shooting date / time information, and shooting conditions (scanning conditions, type of light source 11, shooting light quantity, and the like). When the computer has a database function, the data processing unit 140 executes a storage process for information transmitted from the control unit 100. The processing result by the data processing unit 140 can be transmitted to the scanning laser ophthalmoscope 1 (control unit 100) and other devices.

  In both the former case and the latter case, the function of the data processing unit 140 is not limited to the above.

(User interface 150)
The user interface 150 has a display function and an operation / input function. The display function is realized by a display device such as a liquid crystal display (LCD). The display device displays information under the control of the control unit 100.

  The operation / input function is realized by an operation device or an input device. Examples of these are buttons, levers, knobs, mice, keyboards, trackballs and the like. The control unit 100 may be configured to display a graphical user interface (GUI) on the display device. The display device may be a touch screen.

<First configuration example>
A first configuration example of this embodiment will be described with reference to FIGS. 3 and 4. In this example, the configuration shown in FIG. 3 is applied as the light source unit 10 and the light receiving unit 70. That is, the light source unit 10 is provided with a polarizer 13 a and a wave plate 13 b as the optical element 13. Further, the light receiving unit 70 is provided with a wave plate 71 a and a polarizer 71 b as the optical element 71.

  When performing measurement according to this example, a polarization control element (described above) such as a quarter-wave plate that can be disposed at a position between the objective lens 60 and the eye E is retracted from the optical path.

  The polarizer 13a and the wave plate 13b function as a polarization characteristic conversion element that converts the polarization characteristic of the laser light L0 output from the light source 11 into circularly polarized light in the first rotation direction. Here, the rotation direction of the circularly polarized light is defined with respect to the traveling direction of the laser light L0. That is, the rotation direction of the circularly polarized light is the rotation direction when viewed from the viewpoint on the traveling direction side of the laser light L0, or the rotation direction when viewed from the viewpoint opposite to the traveling direction of the laser light L0, Defined. The former can also be said to be the rotation direction when viewed from the viewpoint to which the laser beam L0 travels, or the rotation direction when viewed from the viewpoint on the end point side of the vector indicating the progress of the laser beam L0. The latter can also be said to be the rotation direction when viewed from the viewpoint on the starting point side of the vector indicating the progress of the laser beam L0. In any case, in this configuration example, the definition of the direction of rotation of circularly polarized light is used consistently. The same applies to other examples.

  The polarizer 13a includes, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, and converts the polarization characteristics of the laser light L0 output from the light source 11 into linearly polarized light in the first direction. This first direction is, for example, the vertical direction or the horizontal direction.

  The wave plate 13b is made of, for example, a quarter wave plate, Fresnel ROM, or the like, and converts the polarization characteristics of the laser light L0 that has passed through the polarizer 13a from linearly polarized light in the first direction to circularly polarized light in the first rotational direction. The first direction of linearly polarized light and the first rotation direction of circularly polarized light correspond to each other. That is, the wave plate 13b converts the linearly polarized laser beam L0 in the first direction into circularly polarized light in a predetermined rotation direction (first rotation direction). For example, when the first direction is the vertical direction, the first rotation direction is clockwise, and when the first direction is the horizontal direction, the first rotation direction is counterclockwise. In this example, the circularly polarized laser beam L0 (laser beam L) obtained in this way is irradiated to the eye E.

  The return light RL from the eye E includes the fundus return light and the anterior segment return light as described above. Further, the return light from the eye E includes a circularly polarized light component in the first rotational direction and a circularly polarized light component in the second rotational direction opposite thereto. The circularly polarized light component in the first rotation direction includes scattered light and fluorescence from the fundus oculi Ef. The circularly polarized light component in the second rotational direction includes specularly reflected light from the cornea, specularly reflected light from the fundus oculi Ef, scattered light and fluorescence from the fundus oculi Ef, and specularly reflected light from a lens (such as the relay lens 50). The scattered light and fluorescence from the fundus oculi Ef include both a circularly polarized light component in the first rotation direction and a circularly polarized light component in the second rotation direction due to the polarization characteristics of the fundus oculi Ef.

  The wave plate 71a and the polarizer 71b function as a polarization component selection element that selectively allows the linearly polarized component in the first direction corresponding to the first rotation direction out of the return light RL from the eye E to be examined. The correspondence between the first rotation direction and the first direction is as described above.

  The wave plate 71a is made of, for example, a quarter wave plate, Fresnel ROM, and the like, and converts the circularly polarized light component in the first rotation direction included in the return light RL into the linearly polarized light component in the first direction. Further, the wave plate 71a converts the circularly polarized light component in the second rotation direction included in the return light RL into a linearly polarized light component in the second direction orthogonal to the first direction. As an example, when the first direction is a vertical direction, the first rotation direction is clockwise, the second rotation direction is counterclockwise, and the second direction is a horizontal direction. Conversely, when the first direction is a horizontal direction, the first rotation direction is counterclockwise, the second rotation direction is clockwise, and the second direction is a vertical direction.

  The polarizer 71b is made of, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, and the like. Of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the wave plate 71a, the polarizer 71b is a straight line in the first direction. The polarization component is selectively passed. That is, the polarizer 71b selectively blocks the linearly polarized light component in the second direction.

  An example of the change in the polarization state of light in this example having such a configuration is shown in FIG. The laser beam L0 output from the light source 11 is converted into a linearly polarized laser beam L0 in the vertical direction by the polarizer 13a, and further converted into a clockwise circularly polarized laser beam L0 by the wave plate 13b. This clockwise circularly polarized laser beam L0 (laser beam L) is irradiated to the eye E.

  As described above, the return light RL from the eye E includes the same clockwise circularly polarized component as that of the irradiated laser light L0 and the counterclockwise circularly polarized component opposite thereto. The return light RL incident on the light receiving unit 70 enters the wave plate 71a. A clockwise circularly polarized light component (scattered light or fluorescence from the fundus oculi Ef) is converted into a vertical linearly polarized light component by the wave plate 71a. Further, the counterclockwise circularly polarized light component (regularly reflected light by the cornea, specularly reflected light by the fundus oculi Ef, scattered light and fluorescence by the fundus oculi Ef, and specularly reflected light by the lens) is converted into a linearly polarized light component in the horizontal direction by the wave plate 71a. Converted.

  The linearly polarized light component in the vertical direction generated by the wave plate 71a passes through the polarizer 71b and reaches the light receiving element 74. On the other hand, the horizontal linearly polarized light component generated by the wave plate 71 a is blocked by the polarizer 71 b and does not reach the light receiving element 74. That is, the light receiving unit 70 is configured to selectively receive a linearly polarized light component in the vertical direction based on the return light RL. Since the linearly polarized light component in the vertical direction is based on the clockwise circularly polarized light component, it includes information related to scattered light and fluorescence from the fundus oculi Ef. That is, the light reception signal output from the light receiving element 74 includes information regarding the irradiation region SL (see FIG. 2) of the spot light of the laser light L. On the other hand, since the horizontal linearly polarized light component blocked by the polarizer 71b is based on the counterclockwise circularly polarized light component, the received light signal output from the light receiving element 74 is the specularly reflected light from the cornea and the lens. It does not substantially contain information on specularly reflected light. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Second configuration example>
A second configuration example of this embodiment will be described with reference to FIGS. 5 and 6. In this example, the wave plate 13b and the wave plate 71a in the first configuration example are made of the same member.

  As shown in FIG. 5, in this example, a wave plate 80 is provided between the beam splitter 30 and the optical scanner 40. The arrangement of the wave plate 80 is not limited to this and may be between the beam splitter 30 and the eye E to be examined. A quarter-wave plate disposed between the objective lens 60 and the eye E to be examined can be used as the wave plate 80. Also, Fresnel ROM or the like can be used as the wave plate 80.

  The light source unit 10 is provided with a polarizer (also denoted by reference numeral 13) as the optical element 13, and the light receiving unit 70 is provided with a polarizer (also denoted by reference numeral 71) as the optical element 71.

  The polarizer 13 and the wave plate 80 function as a polarization characteristic conversion element that converts the polarization characteristics of the laser light L0 output from the light source 11 into circularly polarized light in the first rotation direction. The polarizer 13 includes, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, and converts the polarization characteristics of the laser light L0 output from the light source 11 into linearly polarized light in the first direction. The wave plate 80 converts the polarization characteristics of the laser light L0 that has passed through the polarizer 13 from linearly polarized light in the first direction to circularly polarized light in the first rotational direction. The circularly polarized laser beam L0 (laser beam L) thus obtained is irradiated to the eye E.

  The wave plate 80 and the polarizer 71 function as a polarization component selection element that selectively passes a linearly polarized light component in the first direction corresponding to the first rotation direction in the return light RL from the eye E to be examined. The wave plate 80 converts the circularly polarized light component in the first rotation direction included in the return light RL into a linearly polarized light component in the first direction. Further, the wave plate 80 converts the circularly polarized light component in the second rotation direction included in the return light RL into a linearly polarized light component in the second direction orthogonal to the first direction. The polarizer 71 is made of, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, and the like. Of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the wave plate 80, the polarizer 71 is a straight line in the first direction. The polarization component is selectively passed. That is, the polarizer 71 selectively blocks the linearly polarized light component in the second direction.

  An example of the change in the polarization state of light in this example having such a configuration is shown in FIG. The laser beam L0 output from the light source 11 is converted into a linearly polarized laser beam L0 in the vertical direction by the polarizer 13, and further converted into a clockwise circularly polarized laser beam L0 by the wave plate 80. This clockwise circularly polarized laser beam L0 (laser beam L) is irradiated to the eye E.

  As described above, the return light RL from the eye E includes the same clockwise circularly polarized component as that of the irradiated laser light L0 and the counterclockwise circularly polarized component opposite thereto. The clockwise circularly polarized light component (scattered light and fluorescence from the fundus oculi Ef) is converted into a vertical linearly polarized light component by the wave plate 80. Further, the counterclockwise circularly polarized light component (regularly reflected light by the cornea, specularly reflected light by the fundus oculi Ef, scattered light and fluorescence by the fundus oculi Ef, and specularly reflected light by the lens) is converted into a linearly polarized light component in the horizontal direction by the wave plate 80. Converted. These linearly polarized light components enter the light receiving unit 70.

  The linearly polarized light component in the vertical direction generated by the wave plate 80 passes through the polarizer 71 and reaches the light receiving element 74. On the other hand, the horizontal linearly polarized light component generated by the wave plate 80 is blocked by the polarizer 71 and does not reach the light receiving element 74. Therefore, the light reception signal output from the light receiving element 74 includes information regarding the spot light irradiation region SL (see FIG. 2) of the laser light L, and includes information regarding regular reflection light by the cornea and regular reflection light by the lens. Does not substantially contain. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Third configuration example>
A third configuration example of this embodiment will be described with reference to FIGS. In this example, the wave plate 13b and the wave plate 71a in the first configuration example are configured by the same member (wave plate 80), and the polarizer 13a and the polarizer 71b are configured by the same member (polarizer 90). It is a thing.

  As shown in FIG. 7, in this example, a polarizer 90 and a wave plate 80 are provided between the beam splitter 30 and the optical scanner 40 in order from the beam splitter 30 side. The arrangement of the polarizer 90 and the wave plate 80 is not limited to this, and may be between the beam splitter 30 and the eye E. However, the polarizer 90 is disposed on the light source unit 10 side and the light receiving unit 70 side with respect to the wave plate 80.

  A quarter-wave plate disposed between the objective lens 60 and the eye E to be examined can also be used as the wave plate 80. Also, Fresnel ROM or the like can be used as the wave plate 80. Further, the polarizer 90 includes, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, and the like.

  An arbitrary optical element 13 is provided in the light source unit 10, and an optional optical element 71 is provided in the light receiving unit 70.

  The polarizer 90 and the wave plate 80 function as a polarization characteristic conversion element that converts the polarization characteristics of the laser light L0 output from the light source 11 into circularly polarized light in the first rotation direction. The polarizer 90 converts the polarization characteristics of the laser light L0 output from the light source 11 into linearly polarized light in the first direction. The wave plate 80 converts the polarization characteristics of the laser light L0 that has passed through the polarizer 13 from linearly polarized light in the first direction to circularly polarized light in the first rotational direction. The circularly polarized laser beam L0 (laser beam L) thus obtained is irradiated to the eye E.

  The wave plate 80 and the polarizer 90 function as a polarization component selection element that selectively passes a linearly polarized light component in the first direction corresponding to the first rotation direction in the return light RL from the eye E to be examined. The wave plate 80 converts the circularly polarized light component in the first rotation direction included in the return light RL into a linearly polarized light component in the first direction. Further, the wave plate 80 converts the circularly polarized light component in the second rotation direction included in the return light RL into a linearly polarized light component in the second direction orthogonal to the first direction. The polarizer 90 selectively passes the linearly polarized light component in the first direction out of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the wave plate 80. That is, the polarizer 90 selectively blocks the linearly polarized light component in the second direction.

  An example of a change in the polarization state of light in this example having such a configuration is shown in FIG. The laser beam L0 output from the light source 11 is converted into a linearly polarized laser beam L0 in the vertical direction by the polarizer 90, and further converted into a clockwise circularly polarized laser beam L0 by the wave plate 80. This clockwise circularly polarized laser beam L0 (laser beam L) is irradiated to the eye E.

  As described above, the return light RL from the eye E includes the same clockwise circularly polarized component as that of the irradiated laser light L0 and the counterclockwise circularly polarized component opposite thereto. The clockwise circularly polarized light component (scattered light and fluorescence from the fundus oculi Ef) is converted into a vertical linearly polarized light component by the wave plate 80. Further, the counterclockwise circularly polarized light component (regularly reflected light by the cornea, specularly reflected light by the fundus oculi Ef, scattered light and fluorescence by the fundus oculi Ef, and specularly reflected light by the lens) is converted into a linearly polarized light component in the horizontal direction by the wave plate 80. Converted.

  The vertical linearly polarized light component generated by the wave plate 80 passes through the polarizer 90, enters the light receiving unit 70, and reaches the light receiving element 74. On the other hand, the horizontal linearly polarized light component generated by the wave plate 80 is blocked by the polarizer 90 and does not enter the light receiving unit 70. Therefore, the light reception signal output from the light receiving element 74 includes information regarding the spot light irradiation region SL (see FIG. 2) of the laser light L, and includes information regarding regular reflection light by the cornea and regular reflection light by the lens. Does not substantially contain. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Fourth configuration example>
A fourth configuration example of this embodiment will be described with reference to FIGS. 9 and 10. In this example, the light source 11 outputs a linearly polarized laser beam L0 in the first direction. The light source unit 10 and the light receiving unit 70 have the configuration shown in FIG.

  The light source unit 10 is provided with a wave plate that converts the polarization characteristics of the linearly polarized laser beam L0 output from the light source 11 into circularly polarized light in the first rotation direction as the optical element 13. The wave plate 13 functions as a polarization characteristic conversion element and a first wave plate. The wave plate 13 is made of, for example, a quarter wave plate, Fresnel ROM, or the like.

  As in the first configuration example, the light receiving unit 70 is provided with a wave plate 71 a and a polarizer 71 b as the optical element 71. The wave plate 71a and the polarizer 71b select a polarized light component that selectively passes a linearly polarized light component in the first direction corresponding to the first rotation direction out of the return light RL of the circularly polarized laser light L from the eye E to be examined. Functions as an element.

  The wave plate 71a converts the circularly polarized light component in the first rotational direction included in the return light RL from the eye E to be converted into the linearly polarized light component in the first direction, and the second rotational direction opposite to the first rotational direction. Are converted into linearly polarized light components in a second direction orthogonal to the first direction. The wave plate 71a functions as a second wave plate. The wave plate 71a is made of, for example, a quarter wave plate, Fresnel ROM, or the like.

  The polarizer 71b selectively passes the linearly polarized light component in the first direction out of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the wave plate 71a. The polarizer 71b is composed of, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, and the like.

  An example of the change in the polarization state of light in this example is shown in FIG. The light source 11 outputs a linearly polarized laser beam L0 in a first direction (vertical direction). This laser beam L0 is converted into a clockwise circularly polarized laser beam L0 by the wave plate 13b. This clockwise circularly polarized laser beam L0 (laser beam L) is irradiated to the eye E.

  As described above, the return light RL from the eye E includes the same clockwise circularly polarized component as that of the irradiated laser light L0 and the counterclockwise circularly polarized component opposite thereto. The return light RL incident on the light receiving unit 70 enters the wave plate 71a. A clockwise circularly polarized light component (scattered light or fluorescence from the fundus oculi Ef) is converted into a vertical linearly polarized light component by the wave plate 71a. Further, the counterclockwise circularly polarized light component (regularly reflected light by the cornea, specularly reflected light by the fundus oculi Ef, scattered light and fluorescence by the fundus oculi Ef, and specularly reflected light by the lens) is converted into a linearly polarized light component in the horizontal direction by the wave plate 71a. Converted.

  The linearly polarized light component in the vertical direction generated by the wave plate 71a passes through the polarizer 71b and reaches the light receiving element 74. On the other hand, the horizontal linearly polarized light component generated by the wave plate 71 a is blocked by the polarizer 71 b and does not reach the light receiving element 74. Therefore, the light reception signal output from the light receiving element 74 includes information regarding the spot light irradiation region SL (see FIG. 2) of the laser light L, and includes information regarding regular reflection light by the cornea and regular reflection light by the lens. Does not substantially contain. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

  As a modification of this example, similarly to the second configuration example, the wave plate 13 and the wave plate 71a can be formed of the same member.

<Fifth configuration example>
A fifth configuration example of this embodiment will be described with reference to FIGS. 11 and 12. In this example, the light source 11 outputs a circularly polarized laser beam L0 in the first rotation direction with respect to the traveling direction. The light source unit 10 and the light receiving unit 70 have the configuration shown in FIG. The light source unit 10 does not need to be provided with the optical element 13 for polarization control.

  The light receiving unit 70 is provided with the same wave plate 71 a and polarizer 71 b as the optical element 71 in the fourth configuration example. The wave plate 71a and the polarizer 71b select a polarized light component that selectively passes a linearly polarized light component in the first direction corresponding to the first rotation direction out of the return light RL of the circularly polarized laser light L from the eye E to be examined. Functions as an element. The wave plate 71a converts the circularly polarized light component in the first rotational direction included in the return light RL from the eye E to be converted into the linearly polarized light component in the first direction, and the second rotational direction opposite to the first rotational direction. Are converted into linearly polarized light components in a second direction orthogonal to the first direction. The wave plate 71a functions as a second wave plate, and is formed of, for example, a quarter wave plate, Fresnel ROM, or the like. The polarizer 71b selectively passes the linearly polarized light component in the first direction out of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the wave plate 71a. The polarizer 71b is composed of, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, and the like.

  An example of a change in the polarization state of light in this example is shown in FIG. The light source 11 outputs a circularly polarized laser beam L0 in the first rotation direction (clockwise) with respect to the traveling direction. The eye E is irradiated with the laser beam L having the same polarization characteristics as the clockwise circularly polarized laser beam L0.

  The return light RL incident on the light receiving unit 70 enters the wave plate 71a. A clockwise circularly polarized light component (scattered light or fluorescence from the fundus oculi Ef) is converted into a vertical linearly polarized light component by the wave plate 71a. Further, the counterclockwise circularly polarized light component (regularly reflected light by the cornea, specularly reflected light by the fundus oculi Ef, scattered light and fluorescence by the fundus oculi Ef, and specularly reflected light by the lens) is converted into a linearly polarized light component in the horizontal direction by the wave plate 71a. Converted.

  The linearly polarized light component in the vertical direction generated by the wave plate 71a passes through the polarizer 71b and reaches the light receiving element 74. On the other hand, the horizontal linearly polarized light component generated by the wave plate 71 a is blocked by the polarizer 71 b and does not reach the light receiving element 74. Therefore, the light reception signal output from the light receiving element 74 includes information regarding the spot light irradiation region SL (see FIG. 2) of the laser light L, and includes information regarding regular reflection light by the cornea and regular reflection light by the lens. It does not contain substantially. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Sixth configuration example>
A sixth configuration example of this embodiment will be described with reference to FIGS. 13 and 14. In this example, the configuration shown in FIG. 13 is applied as the light source unit 10 and the light receiving unit 70. The light source unit 10 is provided with a polarizer 13 c and a first polarization control element 13 d as the optical element 13. Further, the light receiving unit 70 is provided with a second polarization control element 71 c as the optical element 71. When performing measurement according to this example, a polarization control element (described above) such as a quarter-wave plate that can be disposed at a position between the objective lens 60 and the eye E is retracted from the optical path.

  The polarizer 13c and the first polarization control element 13d function as a polarization characteristic conversion element that converts the polarization characteristic of the laser light L0 output from the light source 11 into radial polarization. Radial polarization indicates a polarization state that is polarized in the radial direction. The radial polarization in the present invention includes not only perfect radial polarization but also beam pseudo-radial polarization. Pseudo radial polarization refers to a polarization state in which the direction of polarization in each of a plurality of regions of the beam cross section is linearly polarized in the radial direction from the center.

  The polarizer 13c is composed of, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, etc., and converts the polarization characteristics of the laser light L0 output from the light source 11 into linearly polarized light.

  As the first polarization control element 13d, an optical element formed by bonding a plurality of wave plates (phase plates) made of anisotropic optical crystals such as quartz, and a plurality of linear polarization elements (polarizers) are bonded. An optical element, a photonic crystal element, an optical element using liquid crystal, or the like can be used. The first polarization control element 13d converts the polarization characteristics of the laser light that has passed through the polarizer 13c from linearly polarized light to radial polarized light. In this example, the eye E is irradiated with the radially polarized laser beam L0 (laser beam L) thus obtained.

  The return light RL from the eye E includes the fundus return light and the anterior segment return light as described above. In addition, the return light from the eye E includes a radial polarization component and an azimuth polarization component. The radial polarization component includes specularly reflected light from the cornea, specularly reflected light from the fundus oculi Ef, scattered light and fluorescence from the fundus oculi Ef, and specularly reflected light from a lens (such as the relay lens 50). The azimuth polarization component includes scattered light and fluorescence from the fundus oculi Ef. Here, the scattered light and fluorescence from the fundus oculi Ef include both a radial polarization component and an azimuth polarization component due to the polarization characteristics of the fundus oculi Ef. The azimuth polarization is a polarization direction orthogonal to the radial polarization and indicates a polarization state polarized in the azimuth direction (rotation direction). The azimuth polarized light in the present invention includes not only complete azimuth polarized light but also beam pseudo azimuth polarized light. The pseudo azimuth polarization indicates a polarization state in which the polarization direction in each of a plurality of regions of the beam cross section is linear polarization in a direction orthogonal to the radial direction.

  The second polarization control element 71c functions as a polarization component selection element that selectively passes the azimuth polarization component of the return light RL from the eye E to be examined. As the second polarization control element 71c, an optical element formed by bonding a plurality of wavelength plates (phase plates) made of an anisotropic optical crystal such as quartz, and a plurality of linear polarization elements (polarizers) are bonded. An optical element, a photonic crystal element, an optical element using liquid crystal, or the like can be used.

  An example of the change in the polarization state of light in this example having such a configuration is shown in FIG. The laser beam L0 output from the light source 11 is converted into a linearly polarized laser beam L0 by the polarizer 13c, and further converted into a radially polarized laser beam L0 by the first polarization control element 13d. The subject eye E is irradiated with the radially polarized laser beam L0 (laser beam L).

  As described above, the return light RL from the eye E includes a radial polarization component and an azimuth polarization component orthogonal thereto. The return light RL incident on the light receiving unit 70 is incident on the second polarization control element 71c. The radial polarization component is blocked by the second polarization control element 71 c and does not reach the light receiving element 74. On the other hand, the azimuth polarization component passes through the second polarization control element 71 c and reaches the light receiving element 74. That is, the light receiving unit 70 is configured to selectively receive the azimuth polarization component included in the return light RL. As described above, the azimuth polarization component includes information related to scattered light and fluorescence from the fundus oculi Ef. That is, the light reception signal output from the light receiving element 74 includes information regarding the irradiation region SL (see FIG. 2) of the spot light of the laser light L. On the other hand, since the radial polarization component is blocked by the second polarization control element 71c, the light reception signal output from the light receiving element 74 substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. . Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Seventh configuration example>
A seventh configuration example of this embodiment will be described. In this example, contrary to the sixth configuration example, a case will be described in which the eye to be examined is irradiated with azimuth-polarized laser light and the radially polarized component of the return light is received. For the configuration of the optical system, refer to FIG. 13 of the sixth configuration example.

  The light source unit 10 is provided with a polarizer 13 c and a first polarization control element 13 d as the optical element 13. Further, the light receiving unit 70 is provided with a second polarization control element 71 c as the optical element 71. When performing measurement according to this example, a polarization control element (described above) such as a quarter-wave plate that can be disposed at a position between the objective lens 60 and the eye E is retracted from the optical path.

  The polarizer 13c and the first polarization control element 13d function as a polarization characteristic conversion element that converts the polarization characteristic of the laser light L0 output from the light source 11 into azimuth polarized light. The polarizer 13c is composed of, for example, a polarizing plate, a polarizing beam splitter, a Glan-Thompson polarizing prism, etc., and converts the polarization characteristics of the laser light L0 output from the light source 11 into linearly polarized light. As the first polarization control element 13d, an optical element formed by bonding a plurality of wave plates (phase plates) made of anisotropic optical crystals such as quartz, and a plurality of linear polarization elements (polarizers) are bonded. An optical element, a photonic crystal element, an optical element using liquid crystal, or the like can be used. The first polarization control element 13d converts the polarization characteristics of the laser light that has passed through the polarizer 13c from linearly polarized light to azimuth polarized light. In this example, the eye E is irradiated with the azimuth-polarized laser beam L0 (laser beam L) thus obtained.

  The return light RL from the eye E includes the fundus return light and the anterior segment return light as described above. In addition, the return light from the eye E includes a radial polarization component and an azimuth polarization component. The radial polarization component includes specularly reflected light from the cornea, specularly reflected light from the fundus oculi Ef, scattered light and fluorescence from the fundus oculi Ef, and specularly reflected light from a lens (such as the relay lens 50). The azimuth polarization component includes scattered light and fluorescence from the fundus oculi Ef. Here, the scattered light and fluorescence from the fundus oculi Ef include both a radial polarization component and an azimuth polarization component due to the polarization characteristics of the fundus oculi Ef.

  The second polarization control element 71c functions as a polarization component selection element that selectively passes a radial polarization component of the return light RL from the eye E to be examined. As the second polarization control element 71c, an optical element formed by bonding a plurality of wavelength plates (phase plates) made of an anisotropic optical crystal such as quartz, and a plurality of linear polarization elements (polarizers) are bonded. An optical element, a photonic crystal element, an optical element using liquid crystal, or the like can be used.

  An example of a change in the polarization state of light in this example having such a configuration is shown in FIG. The laser light L0 output from the light source 11 is converted into linearly polarized laser light L0 by the polarizer 13c, and further converted into azimuth-polarized laser light L0 by the first polarization control element 13d. The eye E is irradiated with this azimuth-polarized laser beam L0 (laser beam L).

  As described above, the return light RL from the eye E includes a radial polarization component and an azimuth polarization component orthogonal thereto. The return light RL incident on the light receiving unit 70 is incident on the second polarization control element 71c. The radial polarization component passes through the second polarization control element 71 c and reaches the light receiving element 74. On the other hand, the azimuth polarization component is blocked by the second polarization control element 71 c and does not reach the light receiving element 74. That is, the light receiving unit 70 is configured to selectively receive a radial polarization component included in the return light RL. As described above, the radial polarization component includes information related to scattered light and fluorescence from the fundus oculi Ef. That is, the light reception signal output from the light receiving element 74 includes information regarding the irradiation region SL (see FIG. 2) of the spot light of the laser light L. On the other hand, since the azimuth polarization component is blocked by the second polarization control element 71c, the light reception signal output from the light receiving element 74 substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. . Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Eighth configuration example>
An eighth configuration example of this embodiment will be described with reference to FIGS. 16 and 17. In this example, the light source 11 outputs linearly polarized laser light L0. The light source unit 10 and the light receiving unit 70 have the configuration shown in FIG.

  The light source unit 10 is provided with a polarization characteristic conversion element 13 d as the optical element 13. The light receiving unit 70 is provided with a polarization component selection element 71 c as the optical element 71. When performing measurement according to this example, a polarization control element (described above) such as a quarter-wave plate that can be disposed at a position between the objective lens 60 and the eye E is retracted from the optical path.

  The polarization characteristic conversion element 13d converts the polarization characteristic of the laser light L0 output from the light source 11 from linearly polarized light to radial polarized light. As the polarization characteristic conversion element 13d, an optical element formed by bonding a plurality of wave plates (phase plates) made from an anisotropic optical crystal such as quartz, and an optical element formed by bonding a plurality of linear polarizing elements (polarizers). An element, a photonic crystal element, an optical element using liquid crystal, or the like can be used. In this example, the eye E is irradiated with the radially polarized laser beam L0 (laser beam L) thus obtained.

  The return light RL from the eye E includes the fundus return light and the anterior segment return light as described above. In addition, the return light from the eye E includes a radial polarization component and an azimuth polarization component. The radial polarization component includes specularly reflected light from the cornea, specularly reflected light from the fundus oculi Ef, scattered light and fluorescence from the fundus oculi Ef, and specularly reflected light from a lens (such as the relay lens 50). The azimuth polarization component includes scattered light and fluorescence from the fundus oculi Ef. Here, the scattered light and fluorescence from the fundus oculi Ef include both a radial polarization component and an azimuth polarization component due to the polarization characteristics of the fundus oculi Ef.

  The polarization component selection element 71c selectively passes the azimuth polarization component of the return light RL from the eye E to be examined. As the polarization component selection element 71c, an optical element formed by bonding a plurality of wave plates (phase plates) made of an anisotropic optical crystal such as quartz, and an optical element formed by bonding a plurality of linear polarization elements (polarizers). An element, a photonic crystal element, an optical element using liquid crystal, or the like can be used.

  An example of a change in the polarization state of light in this example having such a configuration is shown in FIG. The linearly polarized laser beam L0 output from the light source 11 is converted into a radially polarized laser beam L0 by the polarization characteristic conversion element 13d. The subject eye E is irradiated with the radially polarized laser beam L0 (laser beam L).

  As described above, the return light RL from the eye E includes a radial polarization component and an azimuth polarization component orthogonal thereto. The return light RL incident on the light receiving unit 70 enters the polarization component selection element 71c. The radial polarization component is blocked by the polarization component selection element 71 c and does not reach the light receiving element 74. On the other hand, the azimuth polarization component passes through the polarization component selection element 71 c and reaches the light receiving element 74. That is, the light receiving unit 70 is configured to selectively receive the azimuth polarization component included in the return light RL. As described above, the azimuth polarization component includes information related to scattered light and fluorescence from the fundus oculi Ef. That is, the light reception signal output from the light receiving element 74 includes information regarding the irradiation region SL (see FIG. 2) of the spot light of the laser light L. On the other hand, since the radial polarization component is blocked by the polarization component selection element 71c, the light reception signal output from the light receiving element 74 does not substantially include information on the regular reflection light by the cornea and the regular reflection light by the lens. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Ninth configuration example>
A ninth configuration example of this embodiment will be described. In this example, as in the eighth configuration example, a light source that outputs linearly polarized laser light is applied. In contrast to the eighth configuration example, azimuth-polarized laser light is applied to the eye to be examined. The case of receiving the radial polarization component of the return light will be described. For the configuration of the optical system, refer to FIG. 16 of the eighth configuration example.

  The light source unit 10 is provided with a polarization characteristic conversion element 13 d as the optical element 13. The light receiving unit 70 is provided with a polarization component selection element 71 c as the optical element 71. When performing measurement according to this example, a polarization control element (described above) such as a quarter-wave plate that can be disposed at a position between the objective lens 60 and the eye E is retracted from the optical path.

  The polarization characteristic conversion element 13d converts the polarization characteristic of the laser light L0 output from the light source 11 from linearly polarized light to azimuth polarized light. As the polarization characteristic conversion element 13d, an optical element formed by bonding a plurality of wave plates (phase plates) made from an anisotropic optical crystal such as quartz, and an optical element formed by bonding a plurality of linear polarizing elements (polarizers). An element, a photonic crystal element, an optical element using liquid crystal, or the like can be used. In this example, the eye E is irradiated with the azimuth-polarized laser beam L0 (laser beam L) thus obtained.

  The return light RL from the eye E includes the fundus return light and the anterior segment return light as described above. In addition, the return light from the eye E includes a radial polarization component and an azimuth polarization component. The radial polarization component includes specularly reflected light from the cornea, specularly reflected light from the fundus oculi Ef, scattered light and fluorescence from the fundus oculi Ef, and specularly reflected light from a lens (such as the relay lens 50). The azimuth polarization component includes scattered light and fluorescence from the fundus oculi Ef. Here, the scattered light and fluorescence from the fundus oculi Ef include both a radial polarization component and an azimuth polarization component due to the polarization characteristics of the fundus oculi Ef.

  The polarization component selection element 71c functions as a polarization component selection element that selectively passes a radial polarization component of the return light RL from the eye E to be examined. As the polarization component selection element 71c, an optical element formed by bonding a plurality of wave plates (phase plates) made of an anisotropic optical crystal such as quartz, and an optical element formed by bonding a plurality of linear polarization elements (polarizers). An element, a photonic crystal element, an optical element using liquid crystal, or the like can be used.

  An example of the change in the polarization state of light in this example having such a configuration is shown in FIG. The linearly polarized laser beam L0 output from the light source 11 is converted into azimuth-polarized laser beam L0 by the polarization characteristic conversion element 13d. The eye E is irradiated with this azimuth-polarized laser beam L0 (laser beam L).

  As described above, the return light RL from the eye E includes a radial polarization component and an azimuth polarization component orthogonal thereto. The return light RL incident on the light receiving unit 70 enters the polarization component selection element 71c. The radial polarization component passes through the polarization component selection element 71 c and reaches the light receiving element 74. On the other hand, the azimuth polarization component is blocked by the polarization component selection element 71 c and does not reach the light receiving element 74. That is, the light receiving unit 70 is configured to selectively receive a radial polarization component included in the return light RL. As described above, the radial polarization component includes information related to scattered light and fluorescence from the fundus oculi Ef. That is, the light reception signal output from the light receiving element 74 includes information regarding the irradiation region SL (see FIG. 2) of the spot light of the laser light L. On the other hand, since the azimuth polarization component is blocked by the polarization component selection element 71c, the light reception signal output from the light receiving element 74 does not substantially include information on the regular reflection light by the cornea and the regular reflection light by the lens. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Tenth configuration example>
A tenth configuration example of this embodiment will be described with reference to FIGS. 19 and 20. In this example, the light source 11 outputs a radially polarized laser beam L0. The light source unit 10 and the light receiving unit 70 have the configuration shown in FIG. The light source unit 10 does not need to be provided with the optical element 13 for polarization control. In addition, the light receiving unit 70 includes a polarization component selection element 71c. When performing measurement according to this example, a polarization control element (described above) such as a quarter-wave plate that can be disposed at a position between the objective lens 60 and the eye E is retracted from the optical path. In this example, the eye E is irradiated with radially polarized laser light L0 (laser light L).

  The return light RL from the eye E includes the fundus return light and the anterior segment return light as described above. In addition, the return light from the eye E includes a radial polarization component and an azimuth polarization component. The radial polarization component includes specularly reflected light from the cornea, specularly reflected light from the fundus oculi Ef, scattered light and fluorescence from the fundus oculi Ef, and specularly reflected light from a lens (such as the relay lens 50). The azimuth polarization component includes scattered light and fluorescence from the fundus oculi Ef. Here, the scattered light and fluorescence from the fundus oculi Ef include both a radial polarization component and an azimuth polarization component due to the polarization characteristics of the fundus oculi Ef.

  The polarization component selection element 71c selectively passes the azimuth polarization component of the return light RL from the eye E to be examined. As the polarization component selection element 71c, an optical element formed by bonding a plurality of wave plates (phase plates) made of an anisotropic optical crystal such as quartz, and an optical element formed by bonding a plurality of linear polarization elements (polarizers). An element, a photonic crystal element, an optical element using liquid crystal, or the like can be used.

  An example of the change in the polarization state of light in this example having such a configuration is shown in FIG. The radially polarized laser beam L0 output from the light source 11 is irradiated to the eye E as the laser beam L through the optical scanner 40 and the like.

  As described above, the return light RL from the eye E includes a radial polarization component and an azimuth polarization component orthogonal thereto. The return light RL incident on the light receiving unit 70 enters the polarization component selection element 71c. The radial polarization component is blocked by the polarization component selection element 71 c and does not reach the light receiving element 74. On the other hand, the azimuth polarization component passes through the polarization component selection element 71 c and reaches the light receiving element 74. That is, the light receiving unit 70 is configured to selectively receive the azimuth polarization component included in the return light RL. As described above, the azimuth polarization component includes information related to scattered light and fluorescence from the fundus oculi Ef. That is, the light reception signal output from the light receiving element 74 includes information regarding the irradiation region SL (see FIG. 2) of the spot light of the laser light L. On the other hand, since the radial polarization component is blocked by the polarization component selection element 71c, the light reception signal output from the light receiving element 74 does not substantially include information on the regular reflection light by the cornea and the regular reflection light by the lens. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Eleventh configuration example>
An eleventh configuration example of this embodiment will be described. In this example, contrary to the tenth configuration example, a light source that outputs azimuth-polarized laser light is applied, the eye to be examined is irradiated with this azimuth-polarized laser light, and the radial polarization component of the return light is received. The case will be described. For the configuration of the optical system, refer to FIG. 19 of the tenth configuration example. The light source unit 10 and the light receiving unit 70 have the configuration shown in FIG. The light source unit 10 does not need to be provided with the optical element 13 for polarization control. In addition, the light receiving unit 70 includes a polarization component selection element 71c. When performing measurement according to this example, a polarization control element (described above) such as a quarter-wave plate that can be disposed at a position between the objective lens 60 and the eye E is retracted from the optical path. In this example, the eye E is irradiated with azimuth-polarized laser light L0 (laser light L).

  The return light RL from the eye E includes the fundus return light and the anterior segment return light as described above. In addition, the return light from the eye E includes a radial polarization component and an azimuth polarization component. The radial polarization component includes specularly reflected light from the cornea, specularly reflected light from the fundus oculi Ef, scattered light and fluorescence from the fundus oculi Ef, and specularly reflected light from a lens (such as the relay lens 50). The azimuth polarization component includes scattered light and fluorescence from the fundus oculi Ef. Here, the scattered light and fluorescence from the fundus oculi Ef include both a radial polarization component and an azimuth polarization component due to the polarization characteristics of the fundus oculi Ef.

  The polarization component selection element 71c selectively allows the radial polarization component of the return light RL from the eye E to pass through. As the polarization component selection element 71c, an optical element formed by bonding a plurality of wave plates (phase plates) made of an anisotropic optical crystal such as quartz, and an optical element formed by bonding a plurality of linear polarization elements (polarizers). An element, a photonic crystal element, an optical element using liquid crystal, or the like can be used.

  An example of the change in the polarization state of light in this example having such a configuration is shown in FIG. The azimuth-polarized laser beam L0 output from the light source 11 is irradiated to the eye E as a laser beam L through the optical scanner 40 and the like.

  As described above, the return light RL from the eye E includes a radial polarization component and an azimuth polarization component orthogonal thereto. The return light RL incident on the light receiving unit 70 enters the polarization component selection element 71c. The radial polarization component passes through the polarization component selection element 71 c and reaches the light receiving element 74. On the other hand, the azimuth polarization component is blocked by the polarization component selection element 71 c and does not reach the light receiving element 74. That is, the light receiving unit 70 is configured to selectively receive a radial polarization component included in the return light RL. As described above, the radial polarization component includes information related to scattered light and fluorescence from the fundus oculi Ef. That is, the light reception signal output from the light receiving element 74 includes information regarding the irradiation region SL (see FIG. 2) of the spot light of the laser light L. On the other hand, since the azimuth polarization component is blocked by the polarization component selection element 71c, the light reception signal output from the light receiving element 74 does not substantially include information on the regular reflection light by the cornea and the regular reflection light by the lens. Therefore, the image data of the front image of the fundus oculi Ef formed by the image forming unit 130 based on the light reception signal substantially does not include information on the regular reflection light by the cornea and the regular reflection light by the lens. That is, a front image that does not include ghost light resulting from regular reflection light by the cornea or the lens is obtained.

<Action and effect>
The operation and effect of the scanning laser ophthalmoscope according to the embodiment will be described. In the embodiment, the light source (11) may be a part of the scanning laser ophthalmoscope (1) or an external device of the scanning laser ophthalmoscope (1).

  The scanning laser ophthalmoscope (1) includes an optical system and an image forming unit (130). The optical system scans the fundus oculi (Ef) by irradiating the eye to be examined (E) with laser light (L), and detects return light (RL) of the laser light (L) from the eye to be examined (E). The image forming unit (130) forms a front image of the fundus (Ef) based on the detection result of the return light (RL).

  The optical system has an optical element group (13, 71) and a light receiving element (74). The optical element group (13, 71) selectively transmits a polarization component substantially different from the return light from the anterior eye portion of the return light (RL) from the fundus (Ef) of the laser light (L). . The light receiving element (74) detects the polarization component that has passed through the optical element group and outputs an electrical signal. The image forming unit (130) forms a front image of the fundus (Ef) based on the electrical signal output from the light receiving element (74).

  According to such a scanning laser ophthalmoscope (1), it is possible to remove ghost light without problems such as a burden on the subject and a decrease in image quality. That is, in the scanning laser ophthalmoscope (1), a mydriatic agent that is a burden on the subject is administered, a confocal stop is used, or linearly polarized laser light is irradiated to the eye. Therefore, it is possible to prevent ghost light from being mixed into the front image of the fundus.

  In the embodiment, a circularly polarized laser beam (L) in a predetermined rotation direction is irradiated to the eye to be examined (E), and an image is formed by detecting a component of circular polarization in the rotation direction in the return light (RL). It can be configured to do so. Examples include the following.

  The optical element group (13, 71) includes a polarization characteristic conversion element (13) and a polarization component selection element (71). The polarization characteristic conversion element (13) converts the polarization characteristic of the laser beam (L0) output from the light source (11) into circularly polarized light in the first rotation direction with respect to the traveling direction of the laser beam (L0). The polarization component selection element (71) selectively selects a linearly polarized component in the first direction corresponding to the first rotation direction from the return light (RL) from the eye (E) of the circularly polarized laser beam (L). To pass through.

  The following configurations can be applied as the polarization characteristic conversion element (13) and the polarization component selection element (71). The polarization characteristic conversion element (13) includes a first polarizer (13a) and a first wave plate (13b). The first polarizer (13a) converts the polarization characteristics of the laser beam (L0) output from the light source (11) into linearly polarized light in the first direction. The first wave plate (13b) converts the polarization characteristics of the laser light (L0) that has passed through the first polarizer (13a) from linearly polarized light in the first direction to circularly polarized light in the first rotational direction. Furthermore, the polarization component selection element (71) includes a second wave plate (71a) and a second polarizer (71b). The second wave plate (71a) converts the circularly polarized light component in the first rotation direction included in the return light (RL) from the eye to be examined (E) into the linearly polarized light component in the first direction, and the first rotation direction. The circularly polarized light component in the second rotational direction opposite to the above is converted into a linearly polarized light component in the second direction orthogonal to the first direction. The second polarizer (71b) selectively passes the linearly polarized light component in the first direction out of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the second wave plate (71a). .

  In the embodiment, the first wave plate (13b) and the second wave plate (71a) can be shared. That is, the first wave plate (13b) and the second wave plate (71a) can be configured as the same member (80). This member (80) is arranged at an arbitrary position of the common part of the optical path of the laser light (L0, L) and the optical path of the return light (RL).

  In addition to the common use of the wave plate, the first polarizer (13a) and the second polarizer (71b) can be configured as the same member (90). This member (90) is disposed at an arbitrary position of the common part of the optical path of the laser light (L0, L) and the optical path of the return light (RL). Further, the member (90) is disposed closer to the light source (11) and the light receiving element (74) than the member (80) as a common wave plate.

  In the embodiment, it is possible to use a light source (11) that outputs linearly polarized laser light. In that case, the following configuration can be applied. The optical element group includes a polarization characteristic conversion element (13) and a polarization component selection element (71). The polarization characteristic conversion element (13) changes the polarization characteristic of the linearly polarized laser beam (L0) output from the light source (11) in the first rotation direction with respect to the traveling direction of the laser beam (L0). To circularly polarized light. The polarization component selection element (71) selectively selects a linearly polarized component in the first direction corresponding to the first rotation direction from the return light (RL) from the eye (E) of the circularly polarized laser beam (L). To pass through.

  In the case of using the light source (11) that outputs linearly polarized laser light, the polarization characteristic conversion element (13) and the polarization component selection element (71) may be configured as follows. The polarization characteristic conversion element (13) includes a first wave plate (13) that converts the polarization characteristic of the linearly polarized laser beam (L0) in the first direction into circularly polarized light in the first rotation direction. The polarization component selection element (71) includes a second wave plate (71a) and a polarizer (71b). The second wave plate (71a) converts the circularly polarized light component in the first rotation direction included in the return light (RL) from the eye to be examined (E) into the linearly polarized light component in the first direction, and the first rotation direction. The circularly polarized light component in the second rotational direction opposite to the above is converted into a linearly polarized light component in the second direction orthogonal to the first direction. The polarizer (71b) selectively passes the linearly polarized light component in the first direction out of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the second wave plate (71a).

  In such a configuration, the first wave plate (13) and the second wave plate (71a) can be configured as the same member. This member is disposed at an arbitrary position of the common part of the optical path of the laser light (L0, L) and the optical path of the return light (RL).

  In the embodiment, it is possible to use a light source (11) that outputs circularly polarized laser light. In that case, the following configuration can be applied. The optical system irradiates the eye to be examined (E) with circularly polarized laser light (L0, L) output from the light source (11) in the first rotation direction with respect to the traveling direction. The optical element group (13, 71) selects the linearly polarized light component in the first direction corresponding to the first rotation direction from the return light (RL) from the eye to be examined (E) of the circularly polarized laser light (L). Let it pass.

  In the case of using the light source (11) that outputs circularly polarized laser light, the polarization component selection element (71) may be configured as follows. In this example, it is not necessary to provide the polarization characteristic conversion element (13). The polarization component selection element (71) includes a wave plate (71a) and a polarizer (71b). The wave plate (71a) converts the circularly polarized light component in the first rotation direction included in the return light (RL) from the eye to be examined (E) into the linearly polarized light component in the first direction, and what is the first rotation direction? The circularly polarized light component in the reverse second rotation direction is converted into a linearly polarized light component in the second direction orthogonal to the first direction. The polarizer (71b) selectively passes the linearly polarized light component in the first direction out of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the wave plate (71a).

  In the embodiment, it is possible to use laser light having a polarization state other than circularly polarized light. Examples are radial polarization and azimuth polarization. In this example, a laser beam (L) of radial polarization (or azimuth polarization) is irradiated to the eye to be examined (E), and an azimuth polarization component (or radial polarization component) of the return light (RL) is detected. It can be configured to form an image. Examples include the following.

  The optical element group (13, 71) includes a polarization characteristic conversion element (13) and a polarization component selection element (71). The polarization characteristic conversion element (13) converts the polarization characteristic of the laser beam (L0) output from the light source (11) into radial polarization. The polarization component selection element (71) selectively passes the azimuth polarization component of the return light (RL) from the subject eye (E) of the radially polarized laser beam (L).

  The following configurations can be applied as the polarization characteristic conversion element (13) and the polarization component selection element (71). The polarization characteristic conversion element (13) includes a polarizer (13c) and a first polarization control element (13d). The polarizer (13c) converts the polarization characteristics of the laser beam (L0) output from the light source (11) into linearly polarized light. The first polarization control element (13d) converts the polarization characteristic of the laser light (L0) that has passed through the polarizer (13c) from linearly polarized light to radial polarized light. Furthermore, the polarization component selection element (71) includes a second polarization control element (71c) that selectively passes the azimuth polarization component of the return light (RL) from the eye to be examined (E). The polarization component selection element (71) may further include a polarizer that converts the azimuth polarization component that has passed through the second polarization control element (71c) into linearly polarized light.

  As another example of using radial polarization and azimuth polarization, the following configuration can be applied. The optical element group (13, 71) includes a polarization characteristic conversion element (13) and a polarization component selection element (71). The polarization property conversion element (13) converts the polarization property of the laser beam (L0) output from the light source (11) into azimuth polarized light. The polarization component selection element (71) selectively passes the radial polarization component of the return light (RL) from the eye (E) of the laser beam (L) of azimuth polarization.

  The following configurations can be applied as the polarization characteristic conversion element (13) and the polarization component selection element (71). The polarization characteristic conversion element (13) includes a polarizer (13c) and a first polarization control element (13d). The polarizer (13c) converts the polarization characteristics of the laser beam (L0) output from the light source (11) into linearly polarized light. The first polarization control element (13d) converts the polarization characteristics of the laser light (L0) that has passed through the polarizer (13c) from linearly polarized light to azimuth polarized light. Furthermore, the polarization component selection element (71) includes a second polarization control element (71c) that selectively allows the radial polarization component to pass through the return light (RL) from the eye to be examined (E). The polarization component selection element (71) may further include a polarizer that converts the radial polarization component that has passed through the second polarization control element (71c) into linearly polarized light.

  In the case of using radial polarization and azimuth polarization, a light source (11) that outputs linearly polarized laser light can be used. In that case, the following configuration can be applied. The optical element group (13, 71) includes a polarization characteristic conversion element (13) and a polarization component selection element (71). The polarization characteristic conversion element (13) converts the polarization characteristic of the linearly polarized laser beam (L0) output from the light source (11) into radial polarization. The polarization component selection element (71) selectively passes the azimuth polarization component of the return light (RL) from the subject eye (E) of the radially polarized laser beam (L).

  In the case of using a light source (11) that uses radial polarization and azimuth polarization and outputs linearly polarized laser light, the following configuration can also be applied. The optical element group (13, 71) includes a polarization characteristic conversion element (13) and a polarization component selection element (71). The polarization characteristic conversion element (13) converts the polarization characteristic of the linearly polarized laser beam (L0) output from the light source (11) into azimuth polarized light. The polarization component selection element (71) selectively passes the radial polarization component of the return light (RL) from the eye (E) of the laser beam (L) of azimuth polarization.

  In the case of using radial polarization and azimuth polarization, it is possible to use a light source (11) that outputs a radially polarized laser beam. In that case, the following configuration can be applied. The optical system irradiates the eye (E) with the radially polarized laser light (L0, L) output from the light source (11). The optical element group (13, 71) includes a polarization component selection element (71c) that selectively passes an azimuth polarization component of the return light (RL) from the subject eye (E) of the radially polarized laser beam (L). Including.

  In the case of using radial polarization and azimuth polarization, a light source (11) that outputs azimuth polarization laser light can be used. In that case, the following configuration can be applied. The optical system irradiates the eye (E) with azimuth-polarized laser light (L0, L) output from the light source (11). The optical element group (13, 71) includes a polarization component selection element (71c) that selectively passes a radial polarization component of the return light (RL) from the eye (E) of the laser beam (L) of azimuth polarization. Including.

  The configuration described above is merely an example for favorably implementing the present invention. Therefore, arbitrary modifications (omitted, replacement, addition, etc.) within the scope of the present invention can be made as appropriate.

DESCRIPTION OF SYMBOLS 1 Scanning laser ophthalmoscope 10 Light source part 11 Light source 13 Optical element 13a Polarizer 13b Wavelength plate 13c Polarizer 13d Polarization control element, polarization characteristic conversion element 70 Light receiving part 71 Optical element 71a Wavelength plate 71b Polarizer 71c Polarization control element, polarization Component selection element 74 Light receiving element 80 Wave plate 90 Polarizer 100 Control unit 130 Image forming unit E Eye to be examined Ef Fundus

Claims (9)

An optical system that scans the fundus by irradiating the eye to be examined with laser light, and detects return light from the eye to be examined of the laser light;
An image forming unit that forms a front image of the fundus based on the detection result of the return light, and a scanning laser ophthalmoscope,
The optical system is
An optical element group that selectively passes a polarization component substantially different from the return light from the anterior ocular segment among the return light from the fundus of the laser light,
A light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal;
The image forming unit forms the front image based on an electrical signal output from the light receiving element ,
The optical system irradiates the eye to be examined with circularly polarized laser light output from a light source and having a first rotational direction with respect to the traveling direction;
The optical element group includes a polarization component selection element that selectively passes a linearly polarized light component in a first direction corresponding to the first rotation direction out of the return light from the subject's eye of the circularly polarized laser light,
The polarization component selection element is:
The circularly polarized light component in the first rotational direction contained in the return light from the eye to be examined is converted into the linearly polarized light component in the first direction, and the circularly polarized light component in the second rotational direction opposite to the first rotational direction A wave plate that converts a linearly polarized light component in a second direction orthogonal to the first direction;
A polarizer that selectively passes the linearly polarized light component in the first direction out of the linearly polarized light component in the first direction and the linearly polarized light in the second direction obtained by the wave plate;
A scanning laser ophthalmoscope characterized by comprising: An optical system that scans the fundus by irradiating the eye to be examined with laser light, and detects return light from the eye to be examined of the laser light;
An image forming unit that forms a front image of the fundus based on the detection result of the return light;
A scanning laser ophthalmoscope comprising:
The optical system is
An optical element group that selectively passes a polarization component substantially different from the return light from the anterior ocular segment among the return light from the fundus of the laser light,
A light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal;
Including
The image forming unit forms the front image based on an electrical signal output from the light receiving element,
The optical element group is:
A polarization characteristic conversion element that converts the polarization characteristics of the laser light output from the light source into radial polarization ;
査型laser ophthalmoscope run you; and a polarization component selection element for selectively passing azimuthal polarized light component of the return light from the eye of the laser beam of the radially polarized light. The polarization characteristic conversion element is:
A polarizer that converts the polarization characteristic of the laser light output from the light source to direct linearly polarized light,
The polarization characteristics before laser light passing through the Kihen photons, and a first polarization control element that converts the radial polarization before Kijika line polarization,
3. The scanning laser ophthalmoscope according to claim 2, wherein the polarization component selection element includes a second polarization control element that selectively passes an azimuth polarization component of the return light from the eye to be examined. An optical system that scans the fundus by irradiating the eye to be examined with laser light, and detects return light from the eye to be examined of the laser light;
An image forming unit that forms a front image of the fundus based on the detection result of the return light;
A scanning laser ophthalmoscope comprising:
The optical system is
An optical element group that selectively passes a polarization component substantially different from the return light from the anterior ocular segment among the return light from the fundus of the laser light,
A light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal;
Including
The image forming unit forms the front image based on an electrical signal output from the light receiving element,
The optical element group is:
A polarization property conversion element that converts the polarization property of the laser light output from the light source into azimuth polarization;
A polarization component selection element that selectively passes a radial polarization component of the return light from the eye to be examined with the azimuth-polarized laser beam;
査型laser ophthalmoscope run you comprising a. The polarization characteristic conversion element is:
A polarizer that converts the polarization characteristics of the laser light output from the light source into linearly polarized light;
A first polarization control element that converts the polarization characteristics of the laser light that has passed through the polarizer from the linearly polarized light into azimuth polarized light;
Including
5. The scanning laser ophthalmoscope according to claim 4, wherein the polarization component selection element includes a second polarization control element that selectively passes a radial polarization component of the return light from the eye to be examined . An optical system that scans the fundus by irradiating the eye to be examined with laser light, and detects return light from the eye to be examined of the laser light;
An image forming unit that forms a front image of the fundus based on the detection result of the return light;
A scanning laser ophthalmoscope comprising:
The optical system is
An optical element group that selectively passes a polarization component substantially different from the return light from the anterior ocular segment among the return light from the fundus of the laser light,
A light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal;
Including
The image forming unit forms the front image based on an electrical signal output from the light receiving element,
The optical element group is:
A polarization characteristic conversion element for converting the polarization characteristic of the laser beam straight line polarized light output from the light source to the radial polarization,
査型laser ophthalmoscope run you; and a polarization component selection element for selectively passing azimuthal polarized light component of the return light from the eye of the laser beam of the radially polarized light. An optical system that scans the fundus by irradiating the eye to be examined with laser light, and detects return light from the eye to be examined of the laser light;
An image forming unit that forms a front image of the fundus based on the detection result of the return light;
A scanning laser ophthalmoscope comprising:
The optical system is
An optical element group that selectively passes a polarization component substantially different from the return light from the anterior ocular segment among the return light from the fundus of the laser light,
A light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal;
Including
The image forming unit forms the front image based on an electrical signal output from the light receiving element,
The optical element group is:
A polarization characteristic conversion element that converts the polarization characteristics of linearly polarized laser light output from a light source into azimuth polarization;
A polarization component selection element that selectively passes a radial polarization component of the return light from the eye to be examined with the azimuth-polarized laser beam;
査型laser ophthalmoscope run you comprising a. An optical system that scans the fundus by irradiating the eye to be examined with laser light, and detects return light from the eye to be examined of the laser light;
An image forming unit that forms a front image of the fundus based on the detection result of the return light;
A scanning laser ophthalmoscope comprising:
The optical system is
An optical element group that selectively passes a polarization component substantially different from the return light from the anterior ocular segment among the return light from the fundus of the laser light,
A light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal;
Including
The image forming unit forms the front image based on an electrical signal output from the light receiving element,
The optical system irradiates a subject's eye with a radially polarized laser beam output from a light source,
Wherein the optical element group,査型laser ophthalmoscope run you comprising a polarization component selection element for selectively passing azimuthal polarized light component of the return light from the eye of the laser beam of the radially polarized light. An optical system that scans the fundus by irradiating the eye to be examined with laser light, and detects return light from the eye to be examined of the laser light;
An image forming unit that forms a front image of the fundus based on the detection result of the return light;
A scanning laser ophthalmoscope comprising:
The optical system is
An optical element group that selectively passes a polarization component substantially different from the return light from the anterior ocular segment among the return light from the fundus of the laser light,
A light receiving element that detects the polarization component that has passed through the optical element group and outputs an electrical signal;
Including
The image forming unit forms the front image based on an electrical signal output from the light receiving element,
The optical system irradiates the eye to be examined with azimuth-polarized laser light output from a light source,
Wherein the optical element group,査型laser ophthalmoscope run you comprising a polarization component selection element for selectively passing radially polarized light component of the return light from the eye of the laser beam of the azimuthal polarization.

Images