Eye imaging device and eye imaging method

Abstract

This eye imaging device images an eye and comprises: a retroreflection unit for retroreflecting light from the eye; a beam splitter disposed on the optical path on which light from the eye reaches the retroreflection unit; and an acquisition unit for acquiring, from the light from the eye, light that was reflected by the retroreflection unit and that passed through the beam splitter.

Description

Eye photographing device and eye photographing method

[0001] The disclosed technology relates to an eye photographing device and an eye photographing method.

[0002] Various eye photographing devices have been developed that can photograph the inside and outside of a subject's eye and its surroundings in order to observe or identify the subject's condition. For example, eye photographing devices are known that can observe the subject's eye, such as the eye of a patient undergoing ophthalmic diagnosis or surgical treatment. For example, technology relating to a device having an optical system that forms a real image of the fundus of the subject's eye is known (see Japanese Patent Publication No. 2000-504251).

[0003] A first aspect of the disclosed technology is an eye photographing device that photographs an eye, comprising: a retroreflecting unit that retroreflects light from the eye; a beam splitter that is arranged on the optical path of the light from the eye until it reaches the retroreflecting unit; and an acquisition unit that acquires the light from the eye that has passed through the retroreflecting unit and the beam splitter.

[0004] A second aspect of the disclosed technology is an eye photographing device for photographing an eye, comprising: a retroreflecting unit that retroreflects light from the eye; a beam splitter that reflects the light from the eye and guides it to the retroreflecting unit and transmits the light retroreflected by the retroreflecting unit; and an acquisition unit that acquires the light from the eye that is retroreflected by the retroreflecting unit and transmitted through the beam splitter.

[0005] A third aspect of the disclosed technology is an imaging device for photographing an eye, comprising: a retroreflecting unit that retroreflects incident light; a beam splitter that transmits light from the eye and guides it to the retroreflecting unit, and reflects the light retroreflected by the retroreflecting unit and guides it to an acquisition unit; and an acquisition unit that acquires the light from the eye that is retroreflected by the retroreflecting unit and reflected by the beam splitter.

[0006] FIG. 1 is a block diagram showing an example of the configuration of an eye photographing apparatus according to the first embodiment. FIG. 2 is a conceptual diagram relating to illumination light onto a target eye in the eye photographing apparatus according to the first embodiment. FIG. 3 is a diagram showing an example of the configuration for reducing stray light in the eye photographing apparatus according to the first embodiment. FIG. 4 is a block diagram showing an example of the configuration of an eye photographing apparatus according to the second embodiment. FIG. 5 is a block diagram showing an example of the configuration of an eye photographing apparatus according to the third embodiment. FIG. 6 is a block diagram showing an example of the configuration of an eye photographing apparatus according to the fourth embodiment. FIG. 7 is a block diagram showing an example of the configuration of an eye photographing apparatus according to the fifth embodiment. FIG. 8 is a block diagram showing an example of the configuration of an eye photographing apparatus according to the sixth embodiment. FIG. 9 is a block diagram showing an example of the configuration of an eye photographing apparatus according to the seventh embodiment. FIG. 10 is a flowchart showing an example of the processing flow in the eye photographing apparatus. FIG. 11 is a block diagram showing an example of the configuration of an eye photographing apparatus according to a modified example of the fourth embodiment.

[0007] Hereinafter, embodiments of the disclosed technology will be described in detail with reference to the drawings. Note that components and processes that perform the same actions and functions are given the same reference numerals throughout the drawings, and redundant explanations may be omitted as appropriate. Also, explanations of configurations that are not directly related to the disclosed technology or well-known configurations may be omitted. Also, the dimensional ratios in the drawings are exaggerated for the sake of explanation and may differ from the actual ratios. Furthermore, each drawing is merely a schematic illustration to allow a sufficient understanding of the disclosed technology. Therefore, the disclosed technology is not limited to the illustrated examples.

[0008] The eye photographing device according to the disclosed technology can be applied to any device that photographs the eye of a human subject (hereinafter referred to as the subject eye) and an area including the subject eye. For example, it can be applied to a device that acquires eye-related images such as fundus images. In this embodiment, for the sake of simplicity, as an example of an eye photographing device having an image acquisition function, the present invention will be described as being applied to an eye photographing device such as an ophthalmic device that allows an observer such as a doctor to observe a subject eye of a patient, for example, the fundus, which is the posterior segment of the eye, and the area around the subject eye, for example, the anterior segment, for the purpose of ophthalmic diagnosis and surgical treatment. It should be noted that the technology disclosed herein is not limited to eye photographing devices such as ophthalmic devices used in ophthalmology.

[0009] [First Embodiment] Fig. 1 shows an example of the configuration of an eye photographing device 10 according to this embodiment. As shown in Fig. 1, the eye photographing device 10 includes an image acquisition unit 20, an eyepiece optical unit 30, and an illumination unit 40.

[0010] In the following description, when the eye photographing device 10 is installed on a horizontal plane parallel to the ground, the interpupillary direction of the subject is referred to as the "Y direction," the direction perpendicular to the horizontal plane on which the eye photographing device 10 is installed is referred to as the "X direction," and the depth direction of the subject's eye OB (i.e., the front-to-back direction of an axis centered on the line of sight of the subject's eye OB) is referred to as the "Z direction." Note that the X and Y directions may be reversed. Furthermore, the X and Y directions may be directions relative to the configuration of the eye photographing device 10. For example, when the eye photographing device 10 is installed in a predetermined position (e.g., on a horizontal plane), the horizontal direction may be referred to as the X direction and the vertical direction may be referred to as the Y direction, or vice versa.

[0011] The image acquisition unit 20 is a functional unit that acquires an image of the target eye OB and acquires an image of the target eye OB using light from the target eye OB. The eyepiece optical unit 30 is a functional unit that guides light from the target eye OB to the image acquisition unit 20 and includes a retroreflecting element 34 that retroreflects light from the target eye OB, guiding the light from the target eye OB to the image acquisition unit 20 via the retroreflecting element 34. Note that retroreflection refers to reflecting incident light in the opposite direction to the incident direction while maintaining the angle of the incident direction. The illumination unit 40 is a functional unit that illuminates the target eye OB and illuminates the target eye OB such that the optical path illuminating the target eye OB does not pass through the retroreflecting element 34. As a result, in the eye photographing device 10, the target eye OB is illuminated by illumination light from the illumination unit 40 without passing through the retroreflecting element 34, and the light from the target eye OB is guided by the eyepiece optical unit 30 to the image acquisition unit 20 via the retroreflecting element 34. The retroreflective element 34 is an example of a retroreflective portion of the present disclosure.

[0012] The eyepiece optical unit 30 includes a retroreflective element 34, a wave plate 36, and a beam splitter 38. It is preferable that the wave plate 36 be a λ / 4 plate. When a λ / 4 plate is used as the wave plate 36, it is preferable that the λ / 4 plate functions over a wide wavelength band from visible light to near-infrared light. Of course, the λ / 4 plate may function over a portion of the wavelength band from visible light to near-infrared light. The beam splitter 38 is disposed on the optical path of light from the target eye OB until it reaches the retroreflective element 34. The eyepiece optical unit 30 functions as an optical system that guides light from the target eye OB to the image acquisition unit 20 via the retroreflective element 34. The eyepiece optical unit 30 is housed in a housing 32.

[0013] The eyepiece optical unit 30 deflects (i.e., reflects) light from the target eye OB by the beam splitter 38 toward the retroreflective element 34, where it is retroreflected. The retroreflected light then passes through the beam splitter 38 and is guided to the image acquisition unit 20. One example of the retroreflective element 34 is an element that uses multiple orthogonal reflective surfaces to reflect light in the direction opposite to the direction of light incident on the element. The retroreflective element 34 is an optical element that reflects light incident perpendicularly toward a reflection site in the opposite direction, and that reflects light incident on the reflection site at any angle of incidence in the opposite direction to the incident direction while maintaining the angle of the incident direction. In this embodiment, a polarizing beam splitter is preferably used as the beam splitter 38. The polarizing beam splitter is an optical element for splitting incident light into reflected light and transmitted light, and one of the S-polarized and P-polarized components of the incident light is reflected and the other is transmitted. That is, light from the target eye OB propagating in the Z direction is reflected by the beam splitter 38 and directed toward the retroreflecting element 34. Meanwhile, the polarization components of the incident light and the reflected light are changed by the wave plate 36, and the light retroreflected by the retroreflecting element 34 passes through the beam splitter 38 and is directed toward the image acquisition unit 20. The retroreflecting element 34, the beam splitter 38, and the image acquisition unit 20 are arranged side by side in a second direction intersecting a first direction connecting the target eye OB and the beam splitter 38.

[0014] The eyepiece optical unit 30 has a beam splitter 38 disposed at a position where an axis De extending along the visual axis (direction of line of sight), which is the central axis of the target eye OB, intersects with an axis Dc extending along the central axis of the imaging lens 22 (described later), so as to reflect light from the target eye OB at a substantially right angle. The central axis of the light reflected at a right angle coincides with the axis Dc extending along the central axis of the imaging lens 22 (described later). A wave plate 36 and a retroreflective element 34 are disposed in this order on the reflection side of the beam splitter 38.

[0015] 1 shows an example in which light from the target eye OB is reflected by the beam splitter 38 at a substantially right angle, but the technology of the present disclosure is not limited to light from the target eye OB being reflected by the beam splitter 38 at a substantially right angle. That is, it is sufficient if light from the target eye OB is reflected by the beam splitter 38 and deflected to the retroreflective element 34, and for example, the beam splitter 38 may be arranged to reflect light at an angle more acute than a right angle, or may be arranged to reflect light at an angle more obtuse than a right angle.

[0016] In addition, in this embodiment, a polarizing beam splitter is used as the beam splitter 38, but the technology of the present disclosure is not limited to using a polarizing beam splitter. For example, the beam splitter 38 may be a reflective mirror such as a half mirror that reflects a portion of the incident light, or a wavelength-selective mirror such as a dichroic mirror that reflects light of a predetermined wavelength.

[0017] In the eyepiece optical unit 30 including the wave plate 36 described above, it is possible to omit the wave plate 36. The wave plate 36 functions effectively when a polarizing beam splitter is used as the beam splitter 38. On the other hand, when a reflective mirror such as a half mirror that simply splits light is used as the beam splitter 38, the optical function of the wave plate 36 is not required, and therefore the wave plate 36 can be omitted.

[0018] Specifically, by using a polarizing beam splitter as the beam splitter 38, the wave plate 36 can reflect and transmit the incident light according to the polarization component, thereby enabling efficient light splitting. Furthermore, when a polarizing beam splitter is used as the beam splitter 38, it is preferable to place a wave plate (e.g., a quarter-wave plate) between the beam splitter 38 and the retroreflective element 34.

[0019] A case will be described where a wave plate is not disposed between the beam splitter 38 and the retroreflective element 34. Light from the eye is split into a polarized component that is transmitted and a polarized component that is reflected by the beam splitter 38, which is a polarizing beam splitter, and the polarized component reflected by the beam splitter 38 heads toward the retroreflective element 34. The light retroreflected by the retroreflective element 34 heads toward the beam splitter 38. The light reflected by the retroreflective element 34 heads toward the beam splitter 38 without changing its polarization state. Therefore, the light does not transmit through the beam splitter 38, but is reflected by the beam splitter 38, making it difficult for it to reach the image acquisition unit 20. Therefore, by disposing a wave plate between the beam splitter 38 and the retroreflective element 34, it is possible to guide the light reflected by the beam splitter 38 to the image acquisition unit 20. That is, the polarized light component reflected by the beam splitter 38 passes through the wave plate 36, the retroreflecting element 34 (reflection), and the wave plate 36 in that order, becoming polarized light component that passes through the beam splitter 38 after passing through the wave plate 36 twice. Therefore, the light reflected by the beam splitter 38 and passing through the wave plate 36 and the retroreflecting element 34 can pass through the beam splitter 38 and reach the image acquisition unit 20. Because the beam splitter 38 transmits all of the light that has passed through the wave plate 36 and the retroreflecting element 34, the image acquisition unit 20 can efficiently acquire the light from the eye that has been reflected by the beam splitter 38. Therefore, by using the beam splitter 38, which is a polarizing beam splitter, and the wave plate 36, it is possible to improve the collection efficiency of light from the eye.

[0020] The housing 32 is attached to a base (not shown) and is configured so as to be in non-contact with the subject holding the target eye OB when photographing the target eye OB. By configuring the eyepiece optical unit 30 so as to be in non-contact with the subject, discomfort felt by the subject due to contact with the eye photographing device 10 is reduced.

[0021] Furthermore, the eyepiece optical unit 30 is positioned at a predetermined distance from the target eye OB. Typical eye photographing devices for capturing retinal images use lens optical systems. Eye photographing devices using lens optical systems often capture fundus images with a distance of several tens of millimeters between the device and the target eye, causing the subject to feel a sense of pressure during image capture. The eye photographing device 10 according to this embodiment can ensure a distance of several hundreds of millimeters or more between the target eye OB and the eyepiece optical unit 30. That is, the distance between the target eye OB and the beam splitter 38, which is closest to the target eye OB in the field of view of the target eye OB, is at least 100 mm or more. This allows the eye photographing device 10 to reduce the sense of pressure felt by the subject during image capture compared to typical eye photographing devices.

[0022] The image acquisition unit 20 acquires an image of the target eye OB, and in the present embodiment, as an example, is configured to function as an imaging unit that images the target eye OB. The image acquisition unit 20 includes an imaging lens 22 and an imaging element 24. The image acquisition unit 20 is an example of an acquisition unit of the present disclosure, and acquires an image of the target eye OB by focusing light from the target eye OB onto the imaging element 24 using the imaging lens 22. Note that the image acquisition unit 20 may be configured to acquire an image of the periphery of the target eye OB in addition to the target eye OB.

[0023] In the image acquisition unit 20, the imaging lens 22 functions as an imaging optical system. The imaging lens 22 forming the imaging optical system can be a single lens or an optical lens formed by a lens group in which a plurality of lenses are combined.

[0024] The imaging lens 22 has a predetermined angle of view, and the position of the pupil of the imaging lens 22 and the position of the pupil of the target eye OB are arranged conjugately so as to be the same as the angle of light converged onto the target eye OB by the retroreflective element 34. Therefore, the beam splitter 38, the retroreflective element 34, and the imaging lens 22 function as an optical system that converges light (signal light) from the target eye OB onto the imaging element 24.

[0025] In the image acquisition unit 20, the imaging lens 22 and the imaging element 24 are arranged in this order on the side of the beam splitter 38 through which light from the target eye OB passes. The central axis of the light from the target eye OB is aligned with the image acquisition direction of the image acquisition unit 20, i.e., the axis Dc along the central axis (i.e., the optical axis) of the imaging lens 22.

[0026] The image acquisition unit 20 may be a photographing device equipped with a photographing lens capable of photographing a subject, and may be applied to a photographing device such as a mobile terminal with a photographing function (for example, a so-called smartphone).

[0027] The illumination unit 40 includes a beam splitter 42, an illumination lens 44, and a light source 46. The illumination unit 40 is an example of an illumination unit of the disclosed technology and functions as an illumination light optical system that illuminates the target eye OB with light from the light source 46. The illumination unit 40 is disposed between the target eye OB and the eyepiece optical unit 30 so that the light from the light source 46 illuminates the target eye OB. Specifically, the beam splitter 42, the illumination lens 44, and the light source 46 are disposed, in this order from the target eye side, in the space between the target eye OB and the beam splitter 38 of the eyepiece optical unit 30. In the illumination unit 40, the beam splitter 42, the illumination lens 44, and the light source 46 are disposed so that the position of the light source 46 and the position of the pupil of the target eye OB are conjugate.

[0028] The beam splitter 42 of the illumination unit 40 is positioned on an axis De that is oriented along the visual axis (direction of gaze) of the target eye OB so as to reflect light from the light source 46 through the illumination lens 44 at approximately a right angle toward the target eye OB.

[0029] 1 shows an example in which light from the light source 46 is reflected by the beam splitter 42 at an approximately right angle, but the technology of the present disclosure is not limited to reflecting light at an approximately right angle by the beam splitter 42. That is, it is sufficient if the light from the light source 46 is reflected by the beam splitter 42 and deflected toward the target eye OB, and for example, the beam splitter 42 may be arranged so as to be reflected at an angle more acute than a right angle, or so as to be reflected at an angle more obtuse than a right angle.

[0030] The light source 46 may be a light source that emits light in the visible light wavelength range to the near-infrared wavelength range, for example, in the range of 450 nm to 1100 nm. Examples of the light source 46 include an LED light source and a laser light source. Alternatively, the light source 46 may be configured using a white light source and an optical filter that transmits light in the visible light wavelength range to the near-infrared wavelength range. Alternatively, the light may be propagated using an optical fiber.

[0031] In this embodiment, a case will be described in which a light source equipped with a light-emitting unit that emits light is used as the light source 46, but the present invention is not limited to this. For example, the light source 46 may be configured to have a light introduction function that introduces light from an external light source into the device without having a light-emitting unit.

[0032] The illumination unit 40 illuminates the target eye OB by concentrating light emitted from the light source 46 at a predetermined position on the target eye OB using the illumination lens 44. Therefore, the illumination lens 44 functions as a concentrating optical system that concentrates light at a predetermined position on the target eye OB. The illumination unit 40 is capable of illuminating the fundus of the target eye OB. Details regarding the concentrating position on the target eye OB illuminated by the illumination unit 40 will be described later. The illumination lens 44 is an example of a concentrating optical system of the disclosed technology.

[0033] The illumination lens 44 forming the light collecting optical system can be a single lens or an optical lens formed by a lens group in which a plurality of lenses are combined. One example of the optical lens is a Fresnel lens.

[0034] In the illumination unit 40, the light source 46 is disposed on an axis Di in the illumination direction, i.e., along the central axis (i.e., optical axis) of the illumination lens 44, and the beam splitter 42 is disposed at the position where the axis De and the axis Di intersect. The beam splitter 42 reflects the light from the light source 46 that has passed through the illumination lens 44 so as to illuminate the target eye OB. Therefore, the illumination unit 40 can illuminate the target eye OB without the optical path of the illumination light that illuminates the target eye OB passing through the retroreflective element 34.

[0035] That is, by disposing the illumination unit 40 in the space between the target eye OB and the eyepiece optical unit 30, the illumination light is not guided directly to the image acquisition unit 20 via the retroreflective element 34. Therefore, scattered light generated when the illumination light from the illumination unit 40 is incident on the retroreflective element 34 is acquired by the image acquisition unit 20 as stray light, and does not have the effect of causing reflections in the acquired image of the target eye OB.

[0036] 1 shows an example in which the illumination unit 40 is disposed inside the housing 32, between the target eye OB and the eyepiece optical unit 30, but the technology of the present disclosure is not limited to this. That is, the illumination unit 40 only needs to illuminate the target eye OB so that the optical path of the illumination light does not pass through the retroreflective element 34, and at least a portion of the illumination unit 40 may be disposed inside the eyepiece optical unit 30. For example, the light source 46, or the illumination lens 44 and at least a portion of the light source 46 may be disposed inside the eyepiece optical unit 30. Furthermore, the entire illumination unit 40 may be disposed inside the eyepiece optical unit 30.

[0037] The above-described eye photographing device 10 can include a display unit 50 that displays an image of the target eye OB acquired by the image acquisition unit 20. The display unit 50 makes it possible to provide an image of the target eye OB to an observer or the like. The display unit 50 is an example of a display unit in the present disclosure.

[0038] As shown in FIG. 1 , the display unit 50 is a functional unit that displays an image of the target eye OB acquired by the image acquisition unit 20 and is connected to the image sensor 24 of the image acquisition unit 20. The display unit 50 includes an image sensor controller 52 and a display 54. The image sensor 24 of the image acquisition unit 20 is an electronic device that converts an image of the target eye OB into a video signal, and the image sensor controller 52 of the display unit 50 is an electronic device that converts the video signal into a display signal and outputs it. The image sensor controller 52 is connected to a display 54, typically an LCD monitor, and outputs the display signal to the display 54. As a result, the image captured by the image sensor 24 is displayed on the display 54. While viewing the image displayed on the display 54, the observer can adjust the positions of the eyepiece optical unit 30 and the image acquisition unit 20 to set an observation position for the target eye OB and its surroundings. The display 54 may also be positioned so that it is visible to the observer. The subject can move relative to the eye photographing device 10 while visually observing the image displayed on the display 54, thereby adjusting the position to enable observation of the target eye OB and the area around the target eye OB.

[0039] The image sensor controller 52 can be realized, for example, by a configuration including a computer equipped with a CPU, RAM, ROM, and input / output interface (not shown), which are connected via a bus capable of transmitting and receiving commands and data. The ROM (not shown) can store an image processing program that executes image processing to allow the observer to properly perceive the captured image. The image processing program is read from the ROM (not shown) and loaded into the RAM, and the image processing program loaded in the RAM is executed by the CPU, thereby operating as the image sensor controller 52 that performs image processing to allow the observer to properly perceive the captured image.

[0040] The image acquisition unit 20 and the display unit 50 may exchange information by wired communication using a wired connection, or may exchange information by wireless communication using a wireless connection.

[0041] Furthermore, the information exchanged between the image acquisition unit 20 and the display unit 50 is not limited to display signals. For example, the information may include operational information of the image acquisition unit 20. An example of the operational information is information indicating the operational status of at least one device, such as the optical magnification of the image acquisition unit 20 and the electrical magnification of the image sensor 24.

[0042] Next, a description will be given of the illumination light that is emitted onto the target eye OB by the illumination unit 40. Fig. 2 shows a conceptual diagram of the position of the illumination light that is focused on the target eye OB.

[0043] First, in the eye photographing device 10, the imaging optical path Le of the imaging optical system formed by the imaging lens 22 of the image acquisition unit 20 is set within the pupil Ea so as to pass through the pupil Ea. This allows the image acquisition unit 20 to acquire a fundus image of the target eye OB. For example, the eyepiece optical unit 30 and the image acquisition unit 20 are adjusted so that the axis of the imaging optical path Le, which is formed by light propagating in a direction along the axis Dc via the retroreflective element 34 and the beam splitter 38, coincides with the axis De, which is in a direction along the visual axis of the target eye OB ( FIG. 1 ). Note that in FIG. 2 , the position of the imaging optical path Le in the pupil Ea is shown within the pupil Ea.

[0044] The illumination unit 40 illuminates the target eye OB with illumination light from a light source 46. The illumination lens 44 focuses the illumination light from the light source 46 on the target eye OB. Note that in FIG. 2 , the position of the illumination light path of the illumination light at the surface of the target eye OB and the pupil Ea of the illumination unit 40 is shown as an illumination light path Li, which is a light flux region. The illumination unit 40 may be configured to illuminate any position on the target eye OB as the illumination light path Li of the illumination light to the target eye OB (e.g., the focusing position of the focused illumination light). However, it is preferable to configure the illumination unit 40 so that it does not overlap with the position of the imaging light path Le of the imaging optical system at the pupil Ea. Configuring the illumination unit 40 so that the position of the illumination light path Li of the illumination light at the pupil Ea does not overlap with the position of the imaging light path Le can prevent illumination light scattered by the pupil Ea from entering the imaging light path Le as stray light.

[0045] A specific example of the illumination unit 40 that illuminates the target eye OB will be described. The illumination unit 40 can be configured to satisfy any of the following examples. In the first example, an illumination light path Li (Li １ ) is an example of the illumination unit 40 configured to have the illumination light path Li (Li １ ) can be applied to an illumination position such as a light collection position by the illumination unit 40. In the first example, the illumination unit 40 has an illumination light path Li (Li １ ) is located in the pupil Ea. The illumination unit 40 of the first example is configured so that the illumination light path Li (Li １ ) is positioned. Therefore, the illumination unit 40 illuminates the target eye OB with illumination light that passes through the pupil Ea and travels along an optical path different from the imaging optical path Le. Therefore, illumination light from the light source 46 can pass through the pupil Ea to illuminate the fundus of the target eye OB. Furthermore, since the positions of the illumination optical path Li and the imaging optical path Le do not overlap at the pupil Ea and are separate optical paths, illumination light scattered at the pupil Ea does not enter the imaging optical path Le as stray light. Therefore, illuminating the target eye OB with illumination light that passes through the pupil Ea by the illumination unit 40 effectively functions to acquire a fundus image for observing the fundus. The illumination unit 40 that illuminates the pupil is an example of a focusing optical unit of the present disclosure.

[0046] The second example is an illumination light path Li (Li ２ In the second example, the illumination unit 40 is configured so that the illumination light path Li (Li ２) is positioned. Light irradiated onto the sclera undergoes multiple scattering in the sclera, allowing the fundus to be illuminated with the multiple-scattered light. Furthermore, because the sclera of the target eye OB is located away from the pupil Ea, the illumination light path Li (Li2) and the imaging light path Le are separated. In this case, it is preferable that the light irradiated onto the sclera does not overlap with the imaging light path Le at the pupil Ea. For example, the illumination unit 40 may limit the size of the luminous flux of the illumination light or control the illumination position so that part of the illumination light for the sclera does not enter the imaging light path Le (details will be described later). The sclera absorbs less light in the near-infrared wavelength range than visible light. Therefore, it is preferable to use a light source that emits light in the near-infrared wavelength range as the light source 46. This is because using light in the near-infrared wavelength range reduces light absorption due to multiple scattering in the sclera. Therefore, the illumination unit 40 can illuminate the fundus of the target eye OB by illuminating the sclera with light. The illumination unit 40 of the second example effectively functions to acquire a fundus image for observing the fundus by illuminating the sclera with irradiation light. The illumination unit 40 that illuminates the sclera is an example of a focusing optical unit of the present disclosure.

[0047] The third example is an example in which the illumination unit 40 is configured to illuminate the anterior segment of the target eye OB. In the third example, the illumination unit 40 is configured so that the illumination optical path Li of the illumination light is positioned at a predetermined position for observing the anterior segment of the target eye OB. When observing the anterior segment of the target eye OB, the size of the anterior segment to be observed can be adjusted by setting the size of the portion where light is focused (focused spot) to a predetermined size. Thus, the anterior segment of the target eye OB can be illuminated by the illumination unit 40. Illumination of the anterior segment of the target eye OB by the illumination unit 40 in the third example effectively functions to acquire an anterior segment image for observing the anterior segment of the target eye OB.

[0048] In the third example, since it is only necessary to observe the anterior segment of the target eye OB, it is possible to omit the imaging lens 22 from the image acquisition unit 20 described above. That is, in an eye photographing device that omits the imaging lens 22, the target eye OB and the imaging element 24 may be set at conjugate positions. That is, the anterior segment of the target eye OB may be set as an object, and the imaging element 24 may be positioned so that an image of the anterior segment is formed on the imaging element 24 by the retroreflective element 34. The imaging element 24 in the third example is an example of an imaging element of the present disclosure.

[0049] The illumination light path Li of the illumination light to the target eye OB, i.e., the illumination position such as the light collection position, may be adjusted by adjusting an optical system including an eyepiece optical unit, an illumination unit, and an image acquisition unit. Note that these adjustments may be performed by a position adjustment unit (described later) based on information regarding the position of the target eye acquired by a position observation unit 70 (described later).

[0050] Furthermore, when an image of the anterior segment of the target eye OB is acquired using the imaging lens 22 and the imaging element 24, the image acquisition unit 20 may adjust the focus by adjusting the focal length of the imaging lens 22 or the distance between the imaging lens 22 and the imaging element 24 so that the focus is aligned with the anterior segment of the target eye OB. In the eye photographing device 10 using the retroreflective element 34, when the focus is adjusted according to the position of the target eye OB when imaging the anterior segment, the focus is adjusted in the opposite direction to the direction of movement of the target eye OB compared to the adjustment direction in a typical lens system. When the target eye OB moves in the direction approaching the eyepiece optical unit 30 (Z direction), the focal position moves away from the eyepiece optical unit 30 via the optical lens. On the other hand, when the retroreflective element 34 is used, when the target eye OB moves in the direction approaching the eyepiece optical unit 30 (Z direction), the focal position moves in the direction approaching the eyepiece optical unit 30. Therefore, when the eye photographing device 10 using the retroreflective element 34 photographs the anterior segment of the eye, the focus adjustment is performed in the opposite direction to that of an eye photographing device using an optical lens.

[0051] Next, the operation of the eye photographing apparatus 10 according to this embodiment will be described. First, a case where the image acquiring section 20 acquires a fundus image of the target eye OB as an image relating to the target eye OB will be described.

[0052] The eye photographing device 10 acquires a fundus image of the target eye OB in the image acquisition unit 20 using light from the eye via the eyepiece optical unit 30 ( FIG. 1 ). That is, light from the fundus of the target eye OB is reflected by the beam splitter 38 of the eyepiece optical unit 30, passes through the wavelength plate 36, and is retroreflected by the retroreflecting element 34. The retroreflected light is collected by the imaging lens of the image acquisition unit 20 and forms an image on the imaging element 24. In this way, the image acquisition unit 20 acquires a fundus image of the target eye OB.

[0053] Meanwhile, illumination light is illuminated onto the fundus of the target eye OB by the illumination unit 40. The illumination light illuminates the fundus of the target eye OB at a position different from the imaging optical path Le of the imaging optical system ( FIG. 2 ). Furthermore, the illumination unit 40 is disposed in the space between the target eye OB and the eyepiece optical unit 30, and the illumination optical path Li is set outside the imaging optical path Le of the imaging optical system. Therefore, the illumination light does not reach the retroreflecting element 34 ( FIG. 1 ). Therefore, scattered light generated when the illumination light from the illumination unit 40 is incident on the retroreflecting element 34 is acquired by the image acquisition unit 20 as stray light, and does not appear in the fundus image of the target eye OB.

[0054] Although the above description has been given of a case where the image acquisition unit 20 acquires a fundus image of the target eye OB, the technology of the present disclosure is not limited to this. Here, a description will be given of a case where the image acquisition unit 20 acquires an anterior segment image of the target eye OB as an image related to the target eye OB.

[0055] The eye photographing device 10 uses light from the anterior segment to acquire an anterior segment image of the target eye OB in the image acquisition unit 20 via the eyepiece optical unit 30. That is, light from the anterior segment of the target eye OB is reflected by the beam splitter 38 of the eyepiece optical unit 30, passes through the wave plate 36, and is retroreflected by the retroreflecting element 34. The retroreflected light is collected by the imaging lens of the image acquisition unit 20 and forms an image on the imaging element 24. In this way, the image acquisition unit 20 acquires an anterior segment image of the target eye OB.

[0056] On the other hand, the anterior segment of the target eye OB is illuminated with illumination light by the illumination unit 40. The illumination light illuminated to the anterior segment of the target eye OB illuminates the target eye OB at a position different from the imaging optical path Le of the imaging optical system. Furthermore, the illumination unit 40 is disposed in the space between the target eye OB and the eyepiece optical unit 30, and the illumination optical path Li is set outside the imaging optical path Le of the imaging optical system, so the illumination light does not reach the retroreflecting element 34. Therefore, scattered light generated when the illumination light from the illumination unit 40 is incident on the retroreflecting element 34 is acquired by the image acquisition unit 20 as stray light, and does not appear in the anterior segment image of the target eye OB.

[0057] As described above, in this embodiment, the illumination unit 40 is disposed in the space between the target eye OB and the eyepiece optical unit 30 so that scattered light generated when illumination light from the illumination unit 40 is incident on the retroreflective element 34 does not become stray light. In order to reduce the amount of light emitted from the illumination unit 40 reaching the eyepiece optical unit 30 and the image acquisition unit 20 (stray light), it is preferable to provide a light-shielding element 48 as a light reduction unit in the space between the illumination unit 40 and the eyepiece optical unit 30, as shown in FIG. 3 . For example, the light-shielding element 48 is disposed so as to surround at least a portion of the light flux area through which the light illuminating the target eye OB passes, thereby reducing leakage light of the light illuminating the target eye OB that travels in a direction different from the target eye OB.

[0058] As described above, in this embodiment, the illumination unit 40 that illuminates the target eye OB is disposed in the space between the target eye OB and the eyepiece optical unit 30 that guides light to the image acquisition unit 20. This prevents the illumination light from reaching the image acquisition unit 20 directly via the retroreflective element 34. Therefore, scattered light generated when the illumination light is incident on the retroreflective element 34 is not acquired by the image acquisition unit 20 as stray light and does not appear in the image of the target eye OB.

[0059] [Second Embodiment] Next, a second embodiment will be described. Since the second embodiment has the same configuration as the first embodiment, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted. In addition, the second embodiment will be described in terms of parts that differ from the first embodiment.

[0060] In the first embodiment, a case has been described in which the beam splitter 42 is disposed on the axis De as the illumination unit 40 so as to reflect light from the light source 46 toward the target eye OB at a substantially right angle. The technology of the present disclosure is not limited to reflecting light from the light source 46 toward the target eye OB by the beam splitter 42. The second embodiment will describe an eye imaging device in which the beam splitter 42 is omitted.

[0061] Fig. 4 shows an example of the configuration of an eye photographing device 10A according to this embodiment. As shown in Fig. 4, the eye photographing device 10A includes an illumination unit 40A instead of the illumination unit 40 shown in Fig. 1. The illumination unit 40A does not include the beam splitter 42 shown in Fig. 1, but includes an illumination lens 44 and a light source 46. Note that the display unit 50 shown in Fig. 1 is omitted in Fig. 4.

[0062] The illumination unit 40A functions as an illumination light optical system that directly illuminates the target eye OB with light from a light source 46 via an illumination lens 44. Similar to the illumination unit 40, the illumination unit 40A is disposed between the target eye OB and the eyepiece optical unit 30. Specifically, the illumination lens 44 and the light source 46 are disposed, in that order from the target eye side, in the space between the target eye OB and the beam splitter 38 of the eyepiece optical unit 30. In the illumination unit 40A, the illumination lens 44 and the light source 46 are disposed so that the position of the light source 46 and the position of the pupil of the target eye OB are conjugate.

[0063] Furthermore, the illumination unit 40 is positioned so that the light source 46 is positioned on the axis Di in the illumination direction, i.e., along the central axis (i.e., optical axis) of the illumination lens 44, and the pupil of the target eye OB is located on the axis Di. That is, the illumination unit 40 is positioned so that the axis Di, which is the axis of light from the light source 46 via the illumination lens 44, is inclined at a predetermined angle from the axis De. The predetermined angle, which is the angle between the axis Di and the axis De of the illumination light, can be set to any angle so that the illumination unit 40A does not interfere with the target eye OB and the eyepiece optical unit 30. Therefore, the illumination unit 40A can illuminate the target eye OB without the optical path of the illumination light illuminating the target eye OB passing through the retroreflective element 34.

[0064] The illumination unit 40A is preferably positioned so as to illuminate the sclera of the target eye OB. Illuminating the sclera of the target eye OB allows light to be effectively scattered in the sclera. Therefore, even when the target eye OB is irradiated with off-axis light whose axis Di is tilted at a predetermined angle from the axis De, the light scattering in the sclera makes it possible to illuminate the fundus and obtain an amount of light sufficient to image the fundus.

[0065] 4 shows an example in which the illumination unit 40A is disposed inside the housing 32, between the target eye OB and the eyepiece optical unit 30, but the technology of the present disclosure is not limited to this. That is, the illumination unit 40A only needs to illuminate the target eye OB so that the optical path of the illumination light does not pass through the retroreflective element 34, and at least a portion of the configuration of the illumination unit 40A may be disposed outside the eyepiece optical unit 30. For example, at least one of the illumination lens 44 and the light source 46 may be disposed outside the eyepiece optical unit 30.

[0066] As described above, in this embodiment, the illumination unit 40A that illuminates the target eye OB is configured without a beam splitter, making it possible to reduce the number of parts in the device that illuminates the target eye OB.

[0067] [Third Embodiment] Next, a third embodiment will be described. Since the third embodiment has the same configuration as the first embodiment, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted. Furthermore, in the third embodiment, only parts that differ from the first embodiment will be described.

[0068] In the first embodiment, a case where the beam splitter 42 is arranged on the axis De as the illumination unit 40 so as to reflect light from the light source 46 toward the target eye OB at a substantially right angle is described. In the third embodiment, an eye photographing device is described in which the light source 46 is arranged on an extension of the axis De.

[0069] Fig. 5 shows an example of the configuration of an eye photographing device 10B according to this embodiment. As shown in Fig. 5, the eye photographing device 10B includes an illumination unit 40B instead of the illumination unit 40 shown in Fig. 1. The illumination unit 40B does not include the beam splitter 42 shown in Fig. 1, and an illumination lens 44B and a light source 46 are arranged so that the axis Di is an extension of the axis De.

[0070] Specifically, the illumination unit 40B includes an illumination lens 44B and a light source 46, arranged in this order from the target eye OB side relative to the eyepiece optical unit 30, on the opposite side from the target eye OB such that the axis Di of the illumination light is in the direction along the axis De. Furthermore, in the illumination unit 40B, the illumination lens 44B and the light source 46 are arranged so that the position of the light source 46 and the position of the pupil of the target eye OB are conjugate. The illumination lens 44B includes a lens with an aperture capable of illuminating with illumination light that covers the angle of view (angle of view of the imaging optical system) at which images are acquired by the image acquisition unit 20. It is preferable, but not limited to, that the aperture of the illumination lens 44B covers the angle of view at which images are acquired by the image acquisition unit 20. For example, the aperture of the illumination lens 44B may be set so that the target eye OB is illuminated at an angle of view smaller than the angle of view at which images are acquired by the image acquisition unit 20.

[0071] The illumination unit 40B illuminates the target eye OB by focusing light emitted from the light source 46 at a predetermined position on the target eye OB using the illumination lens 44. Specifically, the illumination unit 40B focuses light from the light source 46 into the pupil Ea of the target eye OB using the illumination lens 44B. Light from the light source 46 emitted from the illumination lens 44B is focused into the pupil Ea of the target eye OB via the beam splitter 38, but does not travel toward the retroreflective element 34. Therefore, the illumination unit 40B can illuminate the target eye OB without the optical path of the illumination light illuminating the target eye OB passing through the retroreflective element 34. Therefore, the illumination light from the illumination unit 40B does not reach the image acquisition unit 20 directly via the retroreflective element 34. Therefore, scattered light generated when the illumination light from the illumination unit 40 is incident on the retroreflective element 34 is not acquired by the image acquisition unit 20 as stray light.

[0072] As described above, in this embodiment, the illumination light path of the illumination unit 40B that illuminates the target eye OB is set to an optical path different from the imaging light path of the light from the target eye OB, so the illumination light does not reach the image acquisition unit 20 via the retroreflective element 34, and the illumination light does not become stray light and appear in the image of the target eye OB.

[0073] Furthermore, in this embodiment, the illumination unit 40B that illuminates the target eye OB is disposed on the opposite side of the eyepiece optical unit 30 from the target eye OB, i.e., at a position away from the target eye OB. This makes it possible to reduce the sense of oppression felt by the subject, compared to when at least a portion of the illumination unit that illuminates the target eye OB is provided in the space between the eyepiece optical unit 30 (e.g., the beam splitter 38) and the target eye OB.

[0074] [Fourth embodiment] Next, a fourth embodiment will be described. Since the fourth embodiment has the same configuration as the first and third embodiments, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted. Furthermore, parts that differ from the above-described embodiments will be described.

[0075] In the third embodiment, an eye photographing device was described in which the light source 46 was arranged on an extension of the axis De as the illumination unit 40. The fourth embodiment is a modified example in which illumination light is guided in a direction along the axis De. The fourth embodiment also uses a retroreflective element for illumination light.

[0076] An example of the configuration of an eye photographing device 10C according to this embodiment is shown in Fig. 6. As shown in Fig. 6, the eye photographing device 10C includes an illumination unit 40C instead of the illumination unit 40B shown in Fig. 5. The illumination unit 40C includes a retroreflective element 41Ca, a wave plate 41Cb, and a beam splitter 42C, which have the same configuration as the eyepiece optical unit 30 described above.

[0077] Specifically, in the illumination unit 40C, a retroreflective element 41Ca, a wave plate 41Cb, a beam splitter 42C, and a light source 46 are arranged on the opposite side of the eyepiece optical unit 30 from the target eye OB. In addition, in the illumination unit 40C, the retroreflective element 41Ca, the wave plate 41Cb, the beam splitter 42C, and the light source 46 are arranged so that the position of the light source 46 and the position of the pupil of the target eye OB are conjugate.

[0078] The retroreflective element 41Ca and wave plate 41Cb of the illumination unit 40C may be arranged by extending the retroreflective element 34 and wave plate 36 of the eyepiece optical unit 30 described above, or may be arranged as separate components from the retroreflective element 34 and wave plate 36 of the eyepiece optical unit 30. By configuring the retroreflective element 34 and wave plate 36 as extensions, it becomes possible to share the adjustment of the retroreflective element 34 and wave plate 36. Furthermore, by configuring the retroreflective element 34 and wave plate 36 as separate components, they can be configured to have sizes appropriate for the light beam used to capture an image and the light beam used for illumination, allowing for efficient and appropriate use of optical components.

[0079] The illumination unit 40C functions as an optical system that illuminates the target eye OB by guiding light from the light source 46 to the target eye OB via the retroreflecting element 41Ca and the beam splitter 42C. That is, in the illumination unit 40C, light from the light source passes through the beam splitter 42C and proceeds to the retroreflecting element 41Ca. The light retroreflected by the retroreflecting element 41Ca is deflected (i.e., reflected) by the beam splitter 42C toward the target eye OB and focused on the target eye OB. It is preferable that a polarizing beam splitter be used for the beam splitter 42C, as with the beam splitter 38.

[0080] In the illumination unit 40C, a beam splitter 42C is disposed at a position where an axis De extending along the visual axis of the target eye OB intersects with an axis Di extending along the central axis (i.e., the optical axis) of the light source 46, which is the illumination direction. The beam splitter 42C is disposed so that light from the light source 46 passes through, and the transmitted light is retroreflected by a retroreflecting element 41Ca, which reflects the light at a substantially right angle toward the target eye OB. The central axis of the light reflected at a right angle coincides with the axis De. A wave plate 41Cb and a retroreflecting element 41Ca are disposed in this order in the traveling direction of the light from the light source 46 that has passed through the beam splitter 42C.

[0081] 6 shows an example in which the light retroreflected by the retroreflective element 41Ca is reflected by the beam splitter 42C at an approximately right angle, but the technology of the present disclosure is not limited to light being reflected by the beam splitter 42C at an approximately right angle. That is, it is sufficient that the light retroreflected by the retroreflective element 41Ca is directed toward the target eye OB. For example, the beam splitter 42C may be arranged so that the light is reflected at an angle more acute than a right angle, or so that the light is reflected at an angle more obtuse than a right angle.

[0082] 6 shows an example in which an optical system including the eyepiece optical unit 30 including the beam splitter 38 and the image acquisition unit 20 is arranged from the target eye OB side, and an illumination unit 40C including the beam splitter 42C is arranged downstream of the optical system, but the technology of the present disclosure is not limited to this. For example, the illumination unit 40C including the beam splitter 42C may be arranged upstream of the target eye OB side, and an optical system including the eyepiece optical unit 30 including the beam splitter 38 and the image acquisition unit 20 may be arranged downstream.

[0083] Although FIG. 6 illustrates the eyepiece optical unit 30 including the wave plate 36 and beam splitter 38, and the illumination unit 40C including the wave plate 41Cb, the wave plate 36 and wave plate 41Cb may be omitted. As described above, the wave plate 36 functions effectively when a polarizing beam splitter is used for the beam splitter 38, allowing the image acquisition unit to efficiently collect light from the eye. Furthermore, it is preferable that the illumination unit 40C include the wave plate 41Cb. Using a polarizing beam splitter for the beam splitter 42C, like the beam splitter 38 described above, allows light from the light source 46 to be reflected and transmitted according to its polarization component, thereby enabling efficient guidance of the light to the target eye OB. In other words, when a polarizing beam splitter is used for the beam splitter 42C, a wave plate can be placed between the beam splitter 42C and the retroreflective element 41Ca to guide the light transmitted and reflected by the beam splitter 42C to the target eye OB. Specifically, light transmitted through the beam splitter 42C via the wave plate 41Cb and the retroreflective element 41Ca is reflected by the beam splitter 42C and guided to the eyepiece optical unit 30, reaching the target eye OB. When a polarizing beam splitter is used as the beam splitter 38 of the eyepiece optical unit 30, the beam splitter 38 is preferably configured to transmit the polarized component of the light propagating from the beam splitter 42C. On the other hand, when a beam splitter such as a half mirror or sampling mirror that simply splits light is used as the beam splitter 42C, the optical function of the wave plate 41Cb is not required, and therefore the wave plate 41Cb may be omitted.

[0084] In addition, although the present embodiment describes a case where a polarizing beam splitter is used as the beam splitter 42C, the technology of the present disclosure is not limited to the use of a polarizing beam splitter. For example, a reflective mirror such as a half mirror that reflects a portion of the incident light may be used, or a wavelength-selective mirror such as a dichroic mirror that reflects light of a predetermined wavelength may be used.

[0085] As described above, in this embodiment, the illumination unit 40C illuminates the target eye OB by focusing light emitted from the light source 46 at a predetermined position on the target eye OB using the illumination retroreflective element 41Ca. That is, the illumination unit 40C focuses light from the light source 46 within the pupil Ea of the target eye OB using the illumination retroreflective element 41Ca. Light from the light source 46 heading toward the target eye OB travels directly from the beam splitter 42C to the target eye OB and does not travel toward the image acquisition retroreflective element 34. Therefore, the illumination unit 40C can illuminate the target eye OB without the optical path of the illumination light passing through the retroreflective element 34. Therefore, the illumination light from the illumination unit 40C does not reach the image acquisition unit 20 directly via the retroreflective element 34. Therefore, scattered light generated when illumination light from the illumination unit 40C is incident on the retroreflective element 34 is not captured by the image capture unit 20 as stray light.

[0086] As described above, in this embodiment, by using the retroreflective element 41Ca for illumination, it is possible to omit the illumination lens 44. Furthermore, the illumination optical path of the illumination unit 40C that illuminates the target eye OB is a different optical path from the imaging optical path of light from the target eye OB, so the illumination light does not reach the image acquisition unit 20 via the retroreflective element 34, and the illumination light does not become stray light and appear in the image of the target eye OB.

[0087] (Modification) Next, a modification of the fourth embodiment will be described. This modification includes an illumination unit that uses retroreflective elements for illumination, and has the same configuration as the above embodiment. Therefore, the same parts are denoted by the same reference numerals, detailed description is omitted, and only different parts will be described.

[0088] FIG. 11 shows an example of the configuration of an eye photographing device 10C-1 according to a modified example. As shown in FIG. 11, the eye photographing device 10C-1 includes an illumination unit 40C-1 instead of the illumination unit 40C (FIG. 6). The illumination unit 40C-1 includes a light source 46, a retroreflector 41Cc, a wave plate 41Cd, a beam splitter 41Ce, and a beam splitter 41Cf. The illumination unit 40C-1 illuminates the target eye OB using the light source 46, the retroreflector 41Cc, the wave plate 41Cd, the beam splitter 41Ce, and the beam splitter 41Cf. The beam splitter 41Cf may have a configuration similar to that of the beam splitter 42 described above.

[0089] The illumination unit 40C-1 deflects (i.e., reflects) light from the light source 46 by the beam splitter 41Ce toward the retroreflective element 41Cc, and then retroreflects the light by the retroreflective element 41Cc. The illumination unit 40C-1 also passes the light retroreflected by the retroreflective element 41Cc through the beam splitter 41Ce, and deflects (i.e., reflects) the light by the beam splitter 41Cf toward the target eye OB, thereby focusing the light on the target eye OB. Specifically, the illumination unit 40C-1 has the light source 46, beam splitter 41Ce, wave plate 41Cd, retroreflective element 41Cc, and beam splitter 41Cf arranged in the order in which the illumination light travels toward the target eye OB. In the illumination unit 40C-1, similarly to the illumination unit 40C ( FIG. 6 ), the retroreflective element 41Cc, the wave plate 41Cd, the beam splitters 41Ce and 41Cf, and the light source 46 are arranged so that the position of the light source 46 and the position of the pupil of the target eye OB are conjugate. At least a portion of the illumination unit 40C-1 is arranged in the space between the target eye OB and the eyepiece optical unit 30. The example shown in FIG. 11 is an example in which the beam splitter 41Ce is arranged in the space between the target eye OB and the eyepiece optical unit 30.

[0090] That is, a beam splitter 41Ce is disposed on the light emission side of the light source 46. A retroreflecting element 41Cc is disposed on the reflection side of the beam splitter 41Ce from the light source 46, and a wave plate 41Cd is disposed between the beam splitter 41Ce and the retroreflecting element 41Cc. A beam splitter 41Cf is disposed on the retroreflecting side of the light from the retroreflecting element 41Cc. Therefore, the light from the light source 46 is guided to the retroreflecting element 41Cc by the beam splitter 41Ce. The light retroreflected by the retroreflecting element 41Cc passes through the beam splitter 41Ce and is guided by the beam splitter 41Cf along the visual axis (axis De) of the target eye OB.

[0091] In the illumination unit 40C-1, the visual axis (axis De) of the target eye OB and the optical axis (axis Di) of the light source 46 are positioned differently, and the optical axis (axis Dc) of the image acquisition unit 20 intersects with the optical axis (axis Di) of the light source 46. Furthermore, the axis of light retroreflected by the retroreflective element 41Cc from the light source 46 intersects with the visual axis (axis De) of the target eye OB and is positioned differently from the optical axis (axis Dc) of the image acquisition unit 20. Therefore, the light from the light source 46 does not mix with the optical path of light from the target eye OB to the image acquisition unit 20 (i.e., the optical path defined by the axes De and Dc).

[0092] 11 shows an example in which the beam splitters 41Ce and 41Cf reflect light at a substantially right angle, but as described above, the technology of the present disclosure is not limited to the beam splitters 41Ce and 41Cf reflecting light at a substantially right angle. For example, the beam splitters 41Ce and 41Cf may reflect light at a predetermined acute or obtuse angle.

[0093] The above-described beam splitter 41Cf preferably employs a polarizing beam splitter in order to efficiently guide light from the eye to the target eye OB and the image acquisition unit 20. When a polarizing beam splitter is employed for the beam splitter 41Cf, the illumination unit 40C-1 preferably includes a wave plate 41Cd, but the wave plate 41Cd may be omitted. By employing a polarizing beam splitter for the beam splitter 41Cf and disposing the wave plate 41Cd between the beam splitter 41Cf and the retroreflective element 41Cc, the illumination unit 40C-1 can guide light according to its polarization component. In other words, the illumination unit 40C-1 can efficiently guide light to the target eye OB and the image acquisition unit 20.

[0094] Specifically, light from the light source 46 passes through the wave plate 41Cd and the retroreflective element 41Cc and is reflected by the beam splitter 41Cf and guided to the target eye OB. Light from the target eye OB passes through the beam splitter 41Cf and is guided to the image acquisition unit 20 via the eyepiece optical unit 30. Therefore, the beam splitter 41Cf is preferably configured to reflect the polarized component of light from the retroreflective element 41Cc and transmit the polarized component from the eye. On the other hand, if a beam splitter such as a half mirror or sampling mirror that simply splits light is used as the beam splitter 41Cf, the optical function of the wave plate 41Cd is not required, and therefore the wave plate 41Cd may be omitted. As described above, the beam splitter 41Cf is not limited to being a polarizing beam splitter; a reflective mirror or a wavelength-selective mirror may also be used.

[0095] As described above, in this modification, the illumination unit 40C-1, like the illumination unit 40C, illuminates the target eye OB by focusing light emitted from the light source 46 at a predetermined position on the target eye OB using the illumination retroreflective element 41Cc. Light from the light source 46 directed toward the target eye OB is guided toward the target eye OB by the beam splitter 41Cf and does not proceed toward the image acquisition retroreflective element 34. Therefore, the illumination unit 40C-1 can illuminate the target eye OB without the optical path of the illumination light that illuminates the target eye OB passing through the retroreflective element 34. Therefore, the illumination light from the illumination unit 40C-1 does not reach the image acquisition unit 20 directly via the retroreflective element 34. Therefore, scattered light generated when the illumination light from the illumination unit 40C-1 is incident on the retroreflective element 34 is not acquired by the image acquisition unit 20 as stray light.

[0096] As described above, in the modified example, by using the illumination retroreflector 41Cc, it is possible to illuminate the target eye OB without using a lens. Furthermore, since the illumination optical path of the illumination unit 40C-1 is a different optical path from the imaging optical path of light from the target eye OB, the illumination light does not reach the image acquisition unit 20 via the retroreflector 34, and the illumination light does not become stray light and appear in the image of the target eye OB.

[0097] [Fifth Embodiment] Next, a fifth embodiment will be described. Since the fifth embodiment has the same configuration as the above-described embodiments, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted. Furthermore, parts that differ from the above-described embodiments will be described.

[0098] In the first embodiment, a case has been described in which light from the target eye OB is reflected by the beam splitter 38 in the eyepiece optical unit 30, and the reflected light is retroreflected by the retroreflecting element 34, and an image of the target eye OB is acquired by the image acquisition unit 20 using the retroreflected light. The fifth embodiment is an eye photographing device in which the functions of the beam splitter 38 in the eyepiece optical unit 30 and the retroreflecting element 34 regarding light reflection and light transmission are interchanged.

[0099] FIG. 7 shows an example of the configuration of an eye photographing device 10D according to this embodiment. As shown in FIG. 7, the eye photographing device 10D includes an image acquisition unit 20D, an eyepiece optical unit 30D, and an illumination unit 40D, each having the same configuration as the components of the eye photographing device 10B shown in FIG. 5. The eyepiece optical unit 30D includes a retroreflecting element 34 disposed on an axis De along the visual axis of the target eye OB via a beam splitter 38 and a wave plate 36. That is, the beam splitter 38 is disposed so as to pass light from the target eye OB. On the side of the beam splitter 38 through which light from the target eye OB passes, the wave plate 36 and the retroreflecting element 34 are disposed, in that order, from the target eye OB side. The beam splitter 38 also reflects the light retroreflected by the retroreflecting element 34. The image acquisition unit 20D is disposed on the side of the beam splitter 38 through which the light retroreflected by the retroreflecting element 34 is reflected. The beam splitter 38 is preferably a polarizing beam splitter.

[0100] In this embodiment, the image acquisition unit 20D includes a relay optical system that relays the position (conjugate point) where light from the target eye OB is retroreflected by the retroreflecting element 34 and focused to the image sensor 24. Specifically, the image acquisition unit 20D includes a first imaging lens 22Da and a second imaging lens 22Db. When a polarizing beam splitter is used for the beam splitter 38, the image acquisition unit 20D includes a polarizer 23Da and a wave plate 23Db to improve the extinction ratio of light from the eye, that is, to reduce the incidence of stray light having a polarization component different from the light from the eye that enters the image acquisition unit 20 via the beam splitter 38 and the retroreflecting element 34. The polarizer 23Da and the wave plate 23Db are optional. As described above, the wave plate 36 functions effectively when a polarized beam splitter is used for the beam splitter 38, and can guide light from the target eye OB to the image acquisition unit 20D and eliminate stray light.If a half mirror or the like is used for the beam splitter 38, the wave plate 36 can be omitted.

[0101] Meanwhile, an illumination unit 40D is disposed on the opposite side of the image acquisition unit 20D with respect to the eyepiece optical unit 30D. That is, an illumination lens and a light source 46 are disposed, in that order from the eyepiece optical unit 30D side, on an axis Dc along the image acquisition direction of the image acquisition unit 20. Note that the illumination unit 40D may include a polarizer 45Da and a wave plate 45Db to control the polarization component of the illumination light, i.e., to prevent the image acquisition unit 20 from acquiring illumination light transmitted through the beam splitter 38 as stray light. The polarizer 45Da and the wave plate 45Db may be omitted. The polarizer 23Da and the wave plate 23Db, as well as the polarizer 45Da and the wave plate 45Db, are examples of a polarization control unit of the present disclosure.

[0102] In this embodiment, light emitted from the light source 46 of the illumination unit 40D is reflected by the beam splitter 38 to illuminate the target eye OB. Light from the light source 46 directed toward the target eye OB is reflected by the beam splitter 38 and directed toward the target eye OB, and does not proceed toward the retroreflective element 34. Therefore, the illumination unit 40D can illuminate the target eye OB without the optical path of the illumination light that illuminates the target eye OB passing through the retroreflective element 34. Therefore, the illumination light from the illumination unit 40D does not reach the image acquisition unit 20D directly via the retroreflective element 34. Therefore, scattered light generated when the illumination light from the illumination unit 40D is incident on the retroreflective element 34 is not acquired by the image acquisition unit 20D as stray light.

[0103] As described above, in this embodiment, even if the functions of the beam splitter 38 and the retroreflective element 34 in the eyepiece optical unit 30 regarding light reflection and light passage are interchanged, the illumination light will not reach the image acquisition unit 20 via the retroreflective element, and the illumination light will not become stray light and appear in the image of the target eye OB.

[0104] 7, the beam splitter 38 of the eyepiece optical unit 30D is shared by the image acquisition unit 20D and the illumination unit 40D, but they can of course be configured independently. For example, the beam splitter 38 of the eyepiece optical unit 30D may be used for the image acquisition unit 20D, and the beam splitter 42 of the illumination unit 40 may be disposed as a separate beam splitter as shown in FIG. 1, and light from the light source 46 may be directed to illuminate the target eye OB.

[0105] [Sixth embodiment] Next, a sixth embodiment will be described. Since the sixth embodiment has the same configuration as the above-described embodiments, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted. Furthermore, parts that differ from the above-described embodiments will be described.

[0106] In the above-described embodiments, a case has been described in which an image of the target eye OB is acquired using light from the target eye OB. The sixth embodiment is an eye photographing device in which both the left eye and the right eye are used as target eyes.

[0107] FIG. 8 shows an example of the configuration of an eye photographing device 10E according to this embodiment. As shown in FIG. 8, the eye photographing device 10E includes components similar to those of the eye photographing device 10D shown in FIG. 7, one for each of the left and right eyes. The eyepiece optical unit 30D ( FIG. 7 ) is shared by both the left and right eyes. That is, the eye photographing device 10E includes an eyepiece optical unit 30D with the same configuration as the eye photographing device 10D ( FIG. 7 ). In this embodiment, the eyepiece optical unit 30D guides light from the left eye OBL and right eye OBR, which are the target eyes OB, to the image acquisition unit 20E. Specifically, the left eye OBL and right eye OBR of the target eyes OB are positioned apart by an interpupillary distance in the X-axis direction and are at the same position in the Y-axis direction. Therefore, the illumination unit 40E and the image acquisition unit 20E are arranged at different positions in the X-axis direction depending on the positions of the left eye OBL and right eye OBR of the target eye OB, and are arranged at a common position in the Y-axis direction.

[0108] The image acquisition unit 20E includes a left-eye image acquisition unit 20EL that acquires an image of the left-eye OBL using light from the left-eye OBL reflected by the beam splitter 38 of the eyepiece optical unit 30D. The image acquisition unit 20E also includes a right-eye image acquisition unit 20ER that acquires an image of the right-eye OBR using light from the right-eye OBR reflected by the beam splitter 38 of the eyepiece optical unit 30D. The left-eye image acquisition unit 20EL and the right-eye image acquisition unit 20ER have the same configuration as the image acquisition unit 20D, and therefore their description will be omitted. The left-eye image acquisition unit 20EL is an example of a left-eye acquisition unit of the technology disclosed herein, and the right-eye image acquisition unit 20ER is an example of a right-eye acquisition unit of the technology disclosed herein.

[0109] The illumination unit 40E uses an illumination lens 44D for illuminating the left eye OBL and the right eye OBR. The illumination lens 44D may be provided in common for both the left eye OBL and the right eye OBR, or may be provided independently for each of the left eye OBL and the right eye OBR. The light source includes a light source 46L for the left eye OBL and a light source 40R for the right eye OBR. Although not shown, the polarizer 45Da and the wave plate 45Db ( FIG. 7 ) described above may be omitted, or may be provided in common for both the left eye OBL and the right eye OBR, or may be provided independently for each of the left eye OBL and the right eye OBR.

[0110] Therefore, light emitted from the light source 46L for the left eye OBL in the illumination unit 40E is reflected by the beam splitter 38 to illuminate the left eye OBL. Similarly, light emitted from the light source 40R for the right eye OBR is reflected by the beam splitter 38 to illuminate the right eye OBR. The light from each of the light source 46L for the left eye OBL and the light source 40R for the right eye OBR is reflected by the beam splitter 38 and directed toward both of the target eyes OB, and does not proceed toward the retroreflecting element 34. Therefore, the illumination unit 40E can illuminate both of the target eyes OB without the optical path of the illumination light that illuminates the target eye OB passing through the retroreflecting element 34. Therefore, the illumination light from the illumination unit 40E does not reach the image acquisition unit 20E directly via the retroreflecting element 34. Therefore, scattered light generated when illumination light from the illumination unit 40E is incident on the retroreflective element 34 is not captured by the image capture unit 20D as stray light.

[0111] In this embodiment, the position of at least some of the components of the eye photographing device 10E is adjustable. Specifically, the eye photographing device 10E is placed on a table 60 equipped with a controller 64. A face rest 62, including a forehead rest and a chin rest, is attached to the table 60 to secure the subject's face to the eye photographing device 10E. The eye photographing device 10E is equipped with a three-axis moving unit 56, which allows the entire eye photographing device 10E to move relative to the table 60 in the X-axis, Y-axis, and Z-axis directions, as well as in the opposite directions. The three-axis moving unit 56 is connected to the controller 64 and controls the movement of the eye photographing device 10E. The controller 64 can be implemented by a general-purpose computer equipped with a central processing unit (CPU). Because the configuration of a general-purpose computer is well known, detailed description thereof will be omitted.

[0112] The eye photographing device 10E includes a drive unit that independently drives a portion of each of the optical systems responsible for the left eye OBL and the right eye OBR so that the position can be adjusted within the eye photographing device 10E. As an example of the drive unit, this embodiment describes a configuration in which the optical system responsible for one of the left eye OBL and the right eye OBR is driven so that the position can be adjusted within the eye photographing device 10E. Specifically, the description will be made of a case in which the optical system for the left eye OBL is adjusted relative to the position of the optical system adjusted for the right eye OBR, which serves as the reference eye described below. The eye photographing device 10E includes a three-axis adjustment unit 52X as a drive unit. The three-axis adjustment unit 52X is configured to adjust the position of the optical system 50L to be adjusted in the X, Y, and Z axial directions and in the opposite direction within the eye photographing device 10E, with the left eye illumination unit 40EL and left eye image acquisition unit 20EL responsible for the left eye OBL being the optical system 50L to be adjusted.

[0113] The eye photographing device 10E also includes focus adjustment units that adjust the focal positions of the left eye OBL and the right eye OBR. Specifically, the eye photographing device 10E includes a focus adjustment unit 54L for the left eye OBL and a focus adjustment unit 54R for the right eye OBR. The focus adjustment unit 54L for the left eye OBL is configured to adjust the position of the optical system 50L to be adjusted in the depth direction of the left eye OBL (the Z-axis direction and the opposite direction) independently of the triaxial movement unit 56 and the triaxial adjustment unit 52X. The focus adjustment unit 54R for the right eye OBR is configured to adjust the position of the optical system 50R to be adjusted, which is the right eye illumination unit 40ER and the right eye image acquisition unit 20ER, in the depth direction of the right eye OBR independently of the triaxial movement unit 56. The triaxial adjustment unit 52X and the focus adjustment units 54L and 54R are connected to and controlled by the controller 64.

[0114] The eye photographing device 10E can acquire an image of the target eye OB desired by the observer by, for example, driving the focus adjustment units 54L and 54R to move the image acquisition unit 20E and adjust the position of the target eye OB. The optical system to be adjusted is not limited to including an illumination unit and an image acquisition unit, as long as the optical system of at least the portion acquiring the image can be adjusted. For example, only the image acquisition unit may be the optical system to be adjusted. That is, the left eye illumination unit 40EL and the left eye image acquisition unit 20EL may each be the optical system to be adjusted. The three-axis moving unit 56, the three-axis adjusting unit 52X, and the focus adjusting units 54L and 54R are examples of a driving unit in the present disclosure. The three-axis moving unit 56, the three-axis adjusting unit 52X, and the focus adjusting units 54L and 54R are examples of a position adjusting unit in the present disclosure. The controller 64 is an example of a control unit in the present disclosure. Furthermore, adjusting the position of the right eye of the target eye OB is an example of a function of the right eye position adjustment unit of the present disclosure, and adjusting the position of the left eye of the target eye OB is an example of a function of the left eye position adjustment unit of the present disclosure. Of course, the adjustment of the positions of the right eye and the left eye of the target eye OB may be performed by at least one of the focus adjustment unit and the three-axis adjustment unit described above, or may be performed by an independent configuration.

[0115] The eye photographing device 10E is provided with the position adjustment unit described above, so that the positions of the left eye OBL and the right eye OBR can be adjusted independently.

[0116] Next, a process flow in the eye photographing device 10E, including a process for adjusting the positions of the left eye OBL and the right eye OBR applied as target eyes, will be described with reference to Fig. 10. The process flow shown in Fig. 10 is executed by the controller 64.

[0117] First, in step S10, the eye photographing device 10E roughly aligns the device by adjusting the position of the eye photographing device 10E, in this case, the height of the table 60, with respect to the position of the face of the subject holding the target eye OB, through operation by the observer. Next, in step S20, the eye photographing device 10E notifies the subject of message information or the like to fix the subject's face on the forehead rest and chin rest of the face rest 62. This allows the subject's face to be fixed relative to the eye photographing device 10E. In step S20, the observer operates the image acquired by the image acquisition unit 20E, and adjusts the position so that the center position of the image and the height position of the target eye OB at least coincide with each other.

[0118] Next, in step S30, the eye photographing device 10E adjusts its position relative to the reference eye. This reference eye adjustment involves designating one of the target eyes OB, the left eye OBL or the right eye OBR, as the reference eye, and adjusting the position of the eye photographing device 10E relative to the designated reference eye. In this embodiment, a case where the right eye OBR is designated as the reference eye will be described. In step S30, the observer operates the eye photographing device 10E to adjust its position so that a fundus image of the right eye OBR can be observed, while referring to the image acquired by the right eye image acquisition unit 20ER. Specifically, the three-axis movement unit 56 drives the eye photographing device 10E to move in each of the X, Y, and Z axial directions and in the opposite direction, thereby adjusting the relative position between the right eye OBR and the eye photographing device 10E so that a fundus image of the reference eye (i.e., the right eye OBR) can be observed.

[0119] Next, in step S40, the eye photographing device 10E adjusts the position of the other target eye OB (i.e., the left eye OBL) by performing interpupillary distance adjustment. Interpupillary distance adjustment is a process for configuring the device so that the left-eye image acquisition unit 20EL and the right-eye image acquisition unit 20ER can acquire images according to the subject's interpupillary distance. Specifically, in step S40, the position of the left-eye optical system in the eye photographing device 10E is adjusted by at least adjusting the position in the X-axis direction so that the fundus image of the left eye OBL can be observed while referring to the image acquired by the left-eye image acquisition unit 20EL, in response to an operation by the observer. In this embodiment, the three-axis adjustment unit 52X is driven to move the optical system to be adjusted, including the left-eye illumination unit 40EL and the left-eye image acquisition unit 20EL, in each of the X-, Y-, and Z-axis directions and in the opposite direction, thereby adjusting the relative position between the left eye OBL and the eye photographing device 10E so that the fundus image of the target eye to be adjusted (i.e., the left eye OBL) can be observed.

[0120] Next, in step S50, the eye photographing device 10E adjusts the focus of each of the left eye OBL and the right eye OBR by driving each of the focus adjustment units 54L and 54R in response to an operation by the observer. Thus, the eye photographing device 10E adjusts the eye photographing device 10E to a position where it can capture fundus images of each of the left eye OBL and the right eye OBR.

[0121] Next, in step S60, the eye photographing device 10E photographs a fundus image in a state in which the positions of the left eye OBL and the right eye OBR have been adjusted by the observer's operation.

[0122] As described above, in this embodiment, even when both the left eye and the right eye are used as target eyes, it is possible to acquire images of each of the left eye and the right eye, and when acquiring each image, the illumination light does not become stray light and appear in the images of the left eye and the right eye.

[0123] Note that the technology disclosed herein is not limited to acquiring images of the left eye OBL and the right eye OBR, respectively. For example, for both target eyes OB, an image of one of the left eye OBL and the right eye OBR may be acquired, and an image of a fixation target or the like may be provided to the other target eye OB. When providing an image of a fixation target or the like to the other target eye OB, a display device that displays the fixation target may be provided instead of the image sensor 24, or an optical device that emits light of the fixation target so that it can be viewed by the target eye OB may be provided. In this case, by providing an exchange device (not shown) that exchangeably drives the image sensor 24 and the device that provides the image, it is possible to exchange the image acquisition process and the image provision process for each of the left eye OBL and the right eye OBR, and perform both processes.

[0124] Furthermore, in the present embodiment, an example of a configuration including a relay optical system that relays the position (conjugate point) where light from the target eye OB (each of the left eye OBL and right eye OBR) is retroreflected by the retroreflecting element 34 and collected to the image sensor 24 ( FIG. 7 ) has been described, but the technology of the present disclosure is not limited to this. For example, the image acquisition units (left eye image acquisition unit 20EL and right eye image acquisition unit 20ER) may include an image sensor and an eyepiece that collects light from the target eye OB (each of the left eye OBL and right eye OBR) on the image sensor.

[0125] [Seventh embodiment] Next, a seventh embodiment will be described. Since the seventh embodiment has the same configuration as the above-described embodiments, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted. Furthermore, parts that differ from the above-described embodiments will be described.

[0126] In the sixth embodiment, a case has been described in which an image of each of the two target eyes OB is acquired, or an image is acquired from one target eye and provided to the other target eye. In the seventh embodiment, an eye photographing device is applied to acquire an image of one of the target eyes OB, either the left or right eye, while providing the other image or observing the target eye.

[0127] Fig. 9 shows an example of the configuration of an eye photographing device 10F according to this embodiment. As shown in Fig. 9, the eye photographing device 10F includes an image display unit 61 and a position observation unit 70. The image display unit 61 is a functional unit that presents an image to the target eye OB by image display. The position observation unit 70 is a functional unit that observes the position of the target eye OB. The image display unit 61 is an example of a projection unit of the technology disclosed herein. Furthermore, the position observation unit 70 is an example of an observation unit of the technology disclosed herein.

[0128] The image display unit 61 presents an image to the target eye OB by displaying an image such as a fixation target. The image may be a structure visible to the subject, or a light spot from a point light source, as an example of an image display such as a fixation target. The image display unit 61, serving as a projection unit in the present disclosure, may project an image positioned conjugate with the posterior segment (i.e., the fundus) of the target eye OB onto the posterior segment of the target eye OB. The position observation unit 70 provides an image for the observer to observe the position of the target eye OB by, for example, acquiring an image of the pupil Ea of the target eye OB using an imaging device. The position observation unit 70 may be equipped with a display device (not shown) that displays the acquired image for position observation. The display device that displays the acquired image is an example of a display unit of the technology disclosed herein. The part of the target eye OB used to confirm the position of the target eye OB is not limited to the pupil Ea, but may be any part of the target eye OB.

[0129] As described above, in this embodiment, by acquiring an image of the target eye OB while providing other images or observing the target eye, it is possible to confirm the alignment of the target eye OB and the state of the target eye OB when acquiring an image of the target eye OB.

[0130] Furthermore, in this embodiment, a position adjustment unit 58 for moving the image acquisition unit 20 can be provided. For example, the position adjustment unit 58 is driven to move the image acquisition unit 20 in accordance with the position of the pupil of the target eye OB acquired by the image acquisition unit 20, and the position of the pupil of the target eye OB on the acquired image is adjusted, thereby making it possible to acquire an image of the target eye OB that the observer desires. The position adjustment unit 58 is an example of a drive unit of the technology disclosed herein.

[0131] Although the disclosed technology has been described above using embodiments, the technical scope of the disclosed technology is not limited to the scope described in the above embodiments. Various modifications or improvements can be made to the above embodiments without departing from the gist of the technology, and such modifications or improvements are also included in the technical scope of the disclosed technology.

[0132] Furthermore, the processes performed in the above-described embodiments can be realized by having a computer execute a program stored in an auxiliary storage device or the like. In this process, at least a portion of the program processing may be implemented by hardware. Furthermore, in order to have a computer execute the processes in the above-described embodiments, a program written in computer-processable code for the processes may be stored on a storage medium such as an optical disk and distributed. The program of the present disclosure can be provided as a program product. A program product includes any type of product for providing a program. For example, a program product includes a program provided via a network such as the Internet, and a non-transitory recording medium such as a CD-ROM or DVD-ROM on which the program is stored.

[0133] All documents, patent applications, and technical standards described herein are incorporated by reference herein to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference. In addition, the disclosure of Japanese Patent Application No. 2023-124985, filed on July 31, 2023, is incorporated by reference in its entirety herein.

Claims

1. An eye imaging device for photographing the eye, The retroreflective portion that retroreflects light from the eye, A beam splitter is positioned in the optical path from the eye to the retroreflective section, An acquisition unit that acquires light from the eye that has passed through the retroreflective section and the beam splitter, An eye imaging device equipped with the following features.

2. The retroreflective section, the beam splitter, and the acquisition section are arranged in a second direction that intersects the first direction connecting the eye and the beam splitter. The acquisition unit acquires light from the eye that has been retroreflected by the retroreflector and transmitted through the beam splitter. The eye imaging device according to claim 1.

3. An eye imaging device for photographing the eye, The retroreflective portion that retroreflects light from the eye, A beam splitter that reflects light from the eye and guides it to the retroreflective section, and transmits the light retroreflected by the retroreflective section, An acquisition unit that acquires light from the eye that is retroreflected by the retroreflector and transmitted through the beam splitter, An eye imaging device equipped with the following features.

4. The acquisition unit has an imaging lens and an image sensor. The imaging lens is positioned such that the pupil of the imaging lens and the pupil of the eye are in a conjugate relationship, and the image of the posterior portion of the eye is formed on the image sensor. The eye imaging device according to claim 2.

5. The acquisition unit has an image sensor, The image sensor is positioned in a conjugate relationship with the anterior segment of the eye and captures images of the anterior segment of the eye. The eye imaging device according to claim 2.

6. It has a light source that emits light, and an illumination unit that illuminates the eye with light from the light source, The retroreflective section and the beam splitter guide the light from the illumination section reflected by the eye to the acquisition section. The eye imaging device according to claim 2.

7. The illumination unit illuminates the eye without passing through the retroreflective unit. The eye imaging device according to claim 6.

8. The illumination unit is positioned on the opposite side of the eye, with the beam splitter in between, and illuminates the eye with light transmitted through the beam splitter. The eye imaging device according to claim 6.

9. The aforementioned beam splitter is a polarizing beam splitter, A polarization control unit is disposed in the optical path of the light that illuminates the eye by the illumination unit, between the light source and the polarization beam splitter. The optical path from the eye to the acquisition unit includes a waveplate positioned in the optical path between the retroreflective unit and the polarizing beam splitter. The eye imaging device according to claim 6.

10. The retroreflective portion retroreflects light from the eye in a first region and retroreflects light illuminating the eye in a second region different from the first region. The illumination unit has another beam splitter located on the optical path of the light illuminating the eye, and positioned on the optical path between the light source and the second region. The second region illuminates the eye via the other beam splitter. The eye imaging device according to claim 6.

11. The illumination unit includes another retroreflective unit that retroreflects the light illuminating the eye, and another beam splitter located on the optical path of the light illuminating the eye, and positioned on the optical path between the light source and the other retroreflective unit. The aforementioned additional retroreflective section illuminates the eye via the aforementioned additional beam splitter. The eye imaging device according to claim 6.

12. The illumination unit has another beam splitter located on the optical path between the eye and the beam splitter, in the optical path from the eye to the beam splitter. The aforementioned beam splitter reflects the light emitted from the light source to illuminate the eye, and transmits the light reflected from the eye. The eye imaging device according to claim 6.

13. The aforementioned beam splitter is a polarizing beam splitter, The optical path from the eye to the acquisition unit includes a waveplate positioned in the optical path between the polarizing beam splitter and the retroreflective unit. The eye imaging device according to claim 12.

14. The beam splitter and the acquisition unit are arranged side by side in a second direction that intersects the first direction connecting the eye, the beam splitter, and the retroreflection unit. The acquisition unit acquires the light from the eye that has been retroreflected by the retroreflector and reflected by the beam splitter. The eye imaging device according to claim 1.

15. A photographic device for photographing the eye, A retroreflective section that retroreflects incident light, A beam splitter that transmits light from the eye and guides it to the retroreflective section, and reflects the light retroreflected by the retroreflective section and guides it to the acquisition section, An acquisition unit that acquires light from the eye that is retroreflected by the retroreflector and reflected by the beam splitter, An eye imaging device equipped with the following features.

16. The acquisition unit has an imaging lens and an image sensor. The imaging lens is positioned such that the pupil of the imaging lens and the pupil of the eye are in a conjugate relationship, and the image of the posterior portion of the eye is formed on the image sensor. The eye imaging device according to claim 14.

17. The acquisition unit has an image sensor, The image sensor is positioned in a conjugate relationship with the anterior segment of the eye and captures images of the anterior segment of the eye. The eye imaging device according to claim 14.

18. It has a light source that emits light, and an illumination unit that illuminates the eye with light from the light source, The retroreflective section and the beam splitter guide the light from the illumination section reflected by the eye to the acquisition section. The eye imaging device according to claim 14.

19. The illumination unit illuminates the eye without passing through the retroreflective unit. The eye imaging device according to claim 18.

20. The illumination unit is positioned on the opposite side of the acquisition unit, with the beam splitter in between. The beam splitter reflects the light from the illumination unit and directs it to the eye. The eye imaging device according to claim 18.

21. The aforementioned beam splitter is a polarizing beam splitter, A polarization control unit is disposed in the optical path of the light that illuminates the eye by the illumination unit, between the light source and the polarization beam splitter. The optical path from the eye to the acquisition unit includes a waveplate positioned in the optical path between the retroreflective unit and the polarizing beam splitter. The eye imaging device according to claim 18.

22. The illumination unit has another beam splitter located on the optical path between the eye and the beam splitter, in the optical path from the eye to the beam splitter. The aforementioned beam splitter reflects light from the light source to illuminate the eye and transmits the light reflected from the eye. The eye imaging device according to claim 18.

23. The aforementioned beam splitter is a polarizing beam splitter, The optical path from the eye to the acquisition unit includes a waveplate positioned in the optical path between the polarizing beam splitter and the retroreflective unit. The eye imaging device according to claim 22.

24. The acquisition unit comprises a left eye acquisition unit for acquiring light from the left eye of the eye, and a right eye acquisition unit for acquiring light from the right eye of the eye, The beam splitter and the retroreflective section guide the light from the right eye to the right eye acquisition section, and the light from the left eye to the left eye acquisition section. The eye imaging device according to claim 1.

25. The acquisition unit comprises a left eye acquisition unit for acquiring light from the left eye of the eye, and a right eye acquisition unit for acquiring light from the right eye of the eye, The beam splitter and the retroreflector guide the light from the right eye to the right eye acquisition unit, and the light from the left eye to the left eye acquisition unit. A left eye position adjustment unit adjusts the position of the left eye acquisition unit relative to the position of the left eye, and a right eye position adjustment unit adjusts the position of the right eye acquisition unit relative to the position of the right eye. The system further comprises a control unit that, after adjusting the position of the corresponding left eye acquisition unit or right eye acquisition unit for one of the left and right eyes, adjusts the position of the other eye. The eye imaging device according to claim 1.

26. An eye imaging device comprising a retroreflective section that retroreflects light from the eye, and an eye imaging method for imaging the eye using the light retroreflected by the retroreflective section, It is positioned in the optical path from the eye to the retroreflective section, and guides the light from the eye toward the retroreflective section, and guides the light from the eye that has been retroreflected by the retroreflective section toward a direction different from the direction toward the retroreflective section. Light guided in a direction different from the direction toward the retroreflective section is acquired. A method of photographing the eye, including the following.