JP2019150425A - Eyeground imaging apparatus - Google Patents

Abstract

To provide an eyeground imaging apparatus capable of appropriately performing alignment adjustment in both forward/rearward directions for switching a viewing angle.SOLUTION: The eyeground imaging apparatus includes: imaging optical systems 10, 20 which project light onto an eyeground Er via objective optical systems 3, 17 and image the eyeground Er on the basis of return light from the eyeground Er; and an alignment optical system 50 which shares at least the objective optical systems 3, 17 with the imaging optical systems 10, 20 and has a light receiving element 55 for capturing an alignment index image on the basis of corneal reflection light of an index flux projected onto a subject eye E. The eyeground imaging apparatus further includes: an alignment adjustment unit which adjusts a positional relationship between the imaging optical systems 10, 20 and the subject eye E; and a lens 53 which switches a viewing angle in the optical imaging systems 10, 20 by at least switching the objective optical systems 3, 17 and optically corrects a change of the size of the alignment index image caused by the switching of the viewing angle of the imaging optical systems.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a fundus imaging apparatus.

  As an ophthalmologic apparatus, an apparatus that projects an image by projecting an alignment index (alignment bright spot) used for alignment of an imaging or inspection optical system with respect to the eye to be examined is known. For example, Patent Document 1 discloses an apparatus for projecting and receiving an alignment index through a part of an optical system for photographing a fundus in a fundus photographing apparatus which is a kind of ophthalmic apparatus.

  In addition, a fundus photographing apparatus that is a kind of ophthalmic apparatus has been proposed in which the angle of view is switched by switching the objective optical system of the photographing optical system. For example, Patent Document 2 discloses an apparatus that switches the angle of view by attaching and detaching a lens attachment to and from the apparatus main body.

JP 2017-127597 JP 2016-123467 A

  When the angle of view is increased by switching the objective optical system, the size of the alignment index changes according to the angle of view. Specifically, when the angle of view is enlarged, the alignment index is reduced (see FIG. 10). If the size of the alignment index is small, it is difficult to adjust to an appropriate alignment state.

  The present disclosure has been made in order to solve the problems of the prior art, and an object of the present disclosure is to provide a fundus imaging apparatus that can easily perform alignment adjustment both before and after the angle-of-view switching.

  The fundus imaging apparatus according to the first aspect of the present disclosure irradiates light to the fundus of the eye to be examined through the objective optical system, and shoots the fundus of the eye to be examined based on return light from the fundus. At least the objective optical system is shared with the photographing optical system, the alignment optical system having a light receiving element for photographing an alignment index image based on the corneal reflection light of the index light beam projected onto the eye to be examined, and the photographing optical system and the eye to be examined Alignment adjusting means for adjusting the positional relationship between the image forming apparatus, field angle switching means for switching the angle of view in the photographing optical system by switching at least the objective optical system, and the alignment index image based on the field angle switching of the photographing optical system Correction means for optically correcting a change in the size of.

  According to the present disclosure, it is easy to appropriately perform alignment adjustment both before and after the view angle switching.

It is a figure which shows schematic structure of the optical system of the fundus imaging apparatus of a present Example. It is a figure which shows schematic structure of the optical system of the fundus imaging apparatus at the time of lens attachment mounting. It is the figure which showed the modification of the optical element for correction | amendment (lens) in the alignment optical system which concerns on 1st Embodiment. It is the figure which showed the 2nd modification of the alignment optical system which concerns on 1st Embodiment. It is the figure which showed the 3rd modification of the alignment optical system which concerns on 1st Embodiment. It is a figure for demonstrating the generation principle of the index light beam by the multiple reflected light which concerns on 2nd Embodiment. Fig. 5 shows the reflection characteristics of a coating applied to a lens surface that produces multiple reflected light. It is the figure which showed the observation image in which the alignment parameter | index image by multiple reflected light is reflected. It is a block diagram which shows the electrical structure of a fundus imaging apparatus. It is a figure showing change of size of an alignment index image accompanying angle of view change, and is a figure for explaining a technical subject of this indication.

<Overview>
Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. Unless otherwise specified, an embodiment using a fundus imaging apparatus (an example of an ophthalmologic apparatus) will be described. Each embodiment can use a part of other embodiment suitably.
<First Embodiment>
The fundus imaging apparatus according to the first embodiment optically corrects a change in the size of a corneal reflection image captured as an alignment index image when the objective optical system is switched and the angle of view of the imaging optical system is switched. .

  The fundus imaging apparatus includes an imaging optical system, an alignment optical system, an alignment adjustment unit, a field angle switching unit, and a correction unit.

  The photographing optical system (see FIGS. 1 and 2) irradiates light on the fundus of the eye to be examined through the objective optical system, and photographs the fundus of the eye to be examined based on return light from the fundus. The photographing optical system may include a light receiving element that receives return light of photographing light from the fundus and may acquire a fundus image based on a signal from the light receiving element.

  The objective optical system (see FIGS. 1 and 2) may be a refraction system, a reflection system, or a combination of both. In the following description, for convenience, the objective optical system will be described as having a plurality of lenses.

  The alignment optical system (see FIGS. 1 and 2) shares at least the objective optical system with the photographing optical system. The alignment optical system includes a light receiving element that captures an alignment index image based on the corneal reflection light of the index light beam projected onto the eye to be examined. The alignment index image may indicate an alignment state in the up / down / left / right direction, or may indicate an alignment state in the front / rear direction (also referred to as a working distance direction). For example, the index light beam is projected from the alignment light source toward the cornea of the eye to be examined and reflected by the cornea. At this time, at least in the light receiving path from the cornea to the light receiving element, the index light beam (more specifically, the corneal reflection light of the index light beam) passes through the objective optical system. Also in the light projection path from the alignment light source to the cornea, the index light beam may be projected onto the cornea via the objective optical system, or the index light beam may be projected onto the cornea without passing through the objective optical system.

  For example, the index light beam may be set so that the index light is incident toward an intermediate point between the center of the radius of curvature of the cornea and the corneal surface in the case of a predetermined proper working distance. That is, in the case of the proper working distance, an alignment light source that is a light source of the index light beam may be arranged at a conjugate position with the intermediate point. Thereby, when the working distance is an appropriate working distance, the cornea reflection image may be formed on the light receiving surface of the light receiving element.

  In the alignment optical system, when the positional relationship between the imaging optical system and the eye to be examined is adjusted by an alignment adjusting unit described later, the positional relationship between the imaging optical system and the eye to be examined is displaced.

  The alignment adjustment unit adjusts the positional relationship between the imaging optical system and the eye to be examined. The positional relationship may be adjusted, for example, in the up / down, front / rear, and left / right directions. The alignment adjustment unit may include a drive unit that displaces the positional relationship between the imaging optical system and the eye to be examined. The drive unit may move the imaging optical system, or may move the subject's face. The drive unit may be a mechanical mechanism or may include an actuator that operates based on a control signal. In the latter case, the alignment adjustment unit may include a control unit of the fundus imaging apparatus, and the positional relationship between the imaging optical system and the eye to be examined may be adjusted based on the alignment index image captured by the light receiving element. Good.

  The field angle switching unit switches the field angle in the photographing optical system by switching at least the power of the objective optical system. In other words, the view angle switching unit changes the magnification of the photographing optical system.

  The field angle switching unit may switch the field angle, for example, by switching the lens configuration in the objective optical system. As an example, the shooting field angle may be selectively switched to one of two predetermined shooting field angles by attaching and detaching an attachment unit such as a lens attachment (see FIG. 2). Here, a narrower field angle is referred to as a “first field angle”, and a wider field angle is referred to as a “second field angle”. For example, the first angle of view may be less than 90 °, and the second angle of view may be 90 ° or more. For example, the first angle of view may be about 45 ° to 60 °, and the second angle of view may be about 90 ° to 150 °.

However, the method of switching the angle of view of the photographing optical system is not limited to the attachment / detachment of the attachment unit. For example, the angle of view may be switched by exchanging part or all of the objective optical system.
<Correction of size of alignment index image>
The correction unit optically corrects a change in the size of the alignment index image based on the field angle switching of the photographing optical system. Specifically, the correction unit suppresses the change amount of the magnification of the alignment index image with respect to the change amount of the magnification of the fundus image when the angle of view is switched.

  The correction unit may include at least a correction optical element. The correction optical element may be provided in an independent optical path with respect to the photographing optical system in the alignment optical system.

  In this case, the correction unit may change the magnification of the alignment index image by changing the distance between the focal point of the corneal reflected light and the light receiving surface of the light receiving element (see FIGS. 1 and 2). More specifically, in the case of the second angle of view, the magnification is switched by moving the focal point and the light receiving surface away from those of the first angle of view. In this case, the correction unit may be one that displaces the focal length in the alignment optical system, one that moves the light receiving element, or a combination of both. For example, the focal length may be changed by displacing the position of the correction optical element (for example, a lens) in the optical axis direction, or the correction optical element is inserted or removed from the optical path of the alignment optical system. May be changed. Further, the focal length may be changed by using a variable focus lens such as a liquid crystal lens as the correction optical element.

  The correcting optical element may have a plurality of focal points having different focal lengths. For example, the correction optical element may be a multifocal lens having at least a first region having a first focal length and a second region having a second focal length in the lens. As an example, the alignment optical system may have the correction optical element shown in FIG. In FIG. 3, the focal length of the hatched region is the first focal length, and the focal length of the non-hatched region is the second focal length. The first focal length corresponds to the first angle of view, the second focal length corresponds to the second angle of view, and the distance from the focal point to the light receiving surface may be longer.

  Instead, the correction unit branches the optical path between the light receiving element and the correction optical element into a plurality of optical paths having different distances between the focal point of the correction optical element and the light receiving surface of each light receiving element. May have a part. For example, the correction unit includes at least two light receiving elements (reference numerals 55a and 55b) and an optical path branching unit, and the optical path branching unit and the optical path branching unit are arranged such that the distance between the focal point of the correction optical element and the light receiving surface of each light receiving element is different from each other. Each light receiving element may be arranged (see FIG. 4). Further, by forming two optical paths having different distances between one light receiving element and the correcting optical element by optical path branching, alignment index images having different magnifications may be simultaneously captured by one light receiving element ( (See FIG. 5). Various beam splitters can be used for the optical path branching unit. For example, the optical path branching unit may be a half mirror, a flip-up mirror, a perforated mirror, or other member.

  The correcting unit may change the size of the alignment index when projected onto the eye to be examined. In other words, a light beam diameter changing unit that changes the light beam diameter of the index light beam projected onto the eye to be examined may be provided. The beam diameter changing unit may be, for example, an alignment light source itself, a variable beam expander, or other optical element as described later.

  The correction optical element is an alignment light source, and the size of the alignment index when projected onto the eye to be examined may be switched by changing the area of the light source. The correction optical element may be an optical element arranged between the alignment light source and the eye to be examined, and may switch the magnification of the alignment index projected onto the eye to be examined. It should be noted that the light source of the index light beam may be different between the case of the first field angle and the case of the second field angle.

  In addition, the fundus imaging apparatus may acquire an observation image of the anterior eye segment in which the alignment index image is optically or electronically superimposed. The anterior ocular segment observation image is acquired based on a signal from the light receiving element of the anterior ocular segment observation optical system. For example, when the light receiving element of the anterior ocular segment observation optical system is also used as the light receiving element of the alignment optical system, an anterior ocular segment observation image on which the alignment index image is superimposed can be acquired. Further, when the light receiving element of the anterior ocular segment observation optical system is separate from the light receiving element of the alignment optical system, the alignment index image may be electronically superimposed on the observation image. In these cases, the anterior ocular segment observation optical system may also be one in which field angle switching is performed in conjunction with the field angle switching unit. Therefore, for example, when the angle of view is switched, the magnification in the anterior ocular segment observation optical system may be optically corrected together with the magnification of the alignment index image.

Second Embodiment
Next, a second embodiment will be described. In the second embodiment, unless otherwise specified, the description of the first embodiment is used for the photographing optical system and the angle-of-view switching unit in the fundus photographing apparatus, and the description is omitted.

  The fundus imaging apparatus according to the second embodiment is a multi-reflection light by any lens surface and cornea included in the objective optical system, and is based on the multi-reflection light (partly) of the observation light. An index image is formed. The observation light here may be used for anterior ocular segment observation or may be used for fundus observation.

  The multiple reflected light is one that is reflected at least once by any lens included in the objective optical system, and then projected onto the cornea and further reflected. Here, the multiple reflected light is defined by at least two reflections. However, in order for the multiple reflected light to actually reach the light receiving surface, the objective optical system and the cornea have three or more odd reflections. It is necessary (see FIG. 6). The reflection other than twice according to the above definition may be caused by any surface of the lens and cornea included in the objective optical system.

  A lens that is included in the objective optical system and reflects observation light to form multiple reflected light may be arranged coaxially with the optical axis of the imaging optical system. In this case, since the cornea of the eye to be examined or another coaxial lens and the surface near the optical axis are parallel, multiple reflected light is formed well.

  Further, the lens surface of the lens that reflects the observation light in order to form the multiple reflection light may be provided with a coating having a reflection characteristic in which the reflectance of the observation light is higher than the reflectance of the photographing light ( (See FIG. 7). At this time, the photographing light is light having a wavelength range different from that of the observation light, and is applied to the fundus in order to obtain a fundus image by the photographing optical system. In the case where the above coating is applied, multiple reflection is unlikely to occur with respect to the photographing light, so that artifacts due to the multiple reflection light are difficult to be superimposed on the photographed image. On the other hand, for the observation light, an alignment index image based on the multiple reflected light is well formed, and this can be used for alignment.

  When the attachment unit (attachment optical system) is attached to the objective optical system, the multiple reflected light of the observation light that forms the alignment index image may be reflected at least by a lens included in the attachment optical system. The attachment optical system is an optical system included in the attachment unit. In this case, the fundus photographing apparatus may be able to project an index light beam (also referred to as a first index light beam) from a light source different from the light source of the observation light. For example, when the attachment optical system is not attached (not attached), a corneal reflection image (first alignment index image) of the first index light beam is acquired, and when the attachment optical system is attached, a corneal reflection image by multiple reflected light is acquired. (Also referred to as a second alignment index image) may be acquired. When the angle of view of the photographing optical system is increased by mounting the attachment optical system, the first alignment index image is reduced with the mounting of the attachment optical system, and the first alignment index, as in the first embodiment. It becomes difficult to perform alignment accurately based on the image. Therefore, since the second alignment index image can be used when the attachment optical system is mounted, the accuracy of alignment is ensured even when the attachment optical system is mounted.

  In the second embodiment, the light receiving element that captures the index image may be used as a light receiving element for fundus photographing or may be a separate body. When the light receiving element that captures the index image is also used as a light receiving element for fundus photographing, an observation image may be acquired based on a signal from the light receiving element. The observation image is a substantially real-time moving image. The observation image may be a fundus observation image. The observation image is displayed on a monitor, for example. Since the alignment index image is superimposed on the fundus observation image, the alignment state can be confirmed simultaneously with the actual fundus image formation state.

<Example>
Hereinafter, an exemplary embodiment of the present invention will be described with reference to the drawings. First, the overall configuration of the ophthalmologic photographing apparatus 1 will be described with reference to FIGS. In this embodiment, the fundus imaging apparatus 1 includes the configuration of a scanning laser opthalmoscope (SLO). The ophthalmologic imaging apparatus 1 is an apparatus that captures a front image of the fundus Er of the eye E. The ophthalmologic imaging apparatus 1 acquires a front image of the fundus Er (an example of an “image of the eye E to be examined”) by scanning the laser beam on the fundus Er and receiving the return light of the laser beam from the fundus Er. .

  In the following description, the ophthalmologic photographing apparatus 1 scans the fundus image by two-dimensionally scanning the laser light collected on the spot on the observation surface based on the operation of the scanning unit (optical scanner). To get. However, the present invention is not necessarily limited to this, and the ophthalmologic photographing apparatus 1 may be a so-called line scan type apparatus. In this case, a linear light beam is scanned on the observation surface. Further, as a device for capturing a front image of the fundus oculi Er, not only a scanning device shown in this embodiment but also a non-scanning device is known. The technique of the present embodiment can be applied to this type of apparatus as appropriate.

  An optical system provided in the ophthalmologic photographing apparatus 1 will be described with reference to FIGS. As shown in FIG. 1, the ophthalmologic photographing apparatus 1 includes an irradiation optical system 10 and a light receiving optical system 20. The ophthalmologic photographing apparatus 1 photographs a fundus image using these optical systems 10 and 20.

  The ophthalmologic photographing apparatus 1 according to the present embodiment switches the photographing field angle by switching the lens configuration in the objective optical system. Specifically, the photographic field angle is selectively switched to one of two predetermined photographic field angles by attaching and detaching the lens attachment 3 (see FIG. 2). Here, the narrower field of view is referred to as “first field angle”, and the wider field of view is referred to as “second field angle”. In this embodiment, the first angle of view is about 45 ° to 60 °, and the second angle of view is about 90 ° to 150 °.

  First, with reference to FIG. 1, an optical system in the case where the shooting field angle is the second field angle will be described. In the present embodiment, when the lens attachment 3 (see FIG. 2) is not attached, the shooting angle of view is set to the second angle of view.

  The irradiation optical system 10 includes a scanning unit 16 and an objective optical system 17. The objective optical system 17 includes at least one lens. As shown in FIG. 1, the irradiation optical system 10 further includes a laser light source 11, a collimating lens 12, a perforated mirror 13, a lens 14 (in this embodiment, a part of the diopter adjustment unit 40), And a lens 15.

  The laser light source 11 is a light source of the irradiation optical system 10. In the present embodiment, laser light from the laser light source 11 is used as photographing light. The laser light source 11 of this embodiment can emit light of a plurality of colors simultaneously or selectively. As an example, in the present embodiment, the laser light source 11 emits light of a total of four colors, three colors in the visible range of blue, green, and red and one color in the infrared range. Light of each color can be emitted simultaneously in any combination. The term “simultaneous” here does not need to be exactly the same, and there may be a time lag in the emission timing of light of each wavelength. For example, in the fundus image formed based on light of each wavelength, the time lag may be a range in which a shift between images due to eye movement is allowed. The laser light source 11 may be formed including, for example, a laser diode (LD) and a super luminescent diode (SLD). In the first embodiment, the light of each color emitted from the laser light source 11 is used for photographing the fundus. Note that a fundus image captured based on fundus reflection light may be referred to as a reflection image, and a fundus image captured based on fluorescence from a fluorescent substance present in the fundus Er may be referred to as a fluorescence image.

  As the reflected image, any or all of an infrared image, a color image, a red-free image, a monochromatic visible image, and the like may be taken. Further, as the fluorescence image, any or all of the contrast fluorescence image and the spontaneous fluorescence image may be taken. The contrast fluorescent image is an image by fluorescence emission of a contrast agent intravenously injected into the fundus Er, and may be, for example, an FA image (fluorescein contrast-enhanced image) or an ICGA image (indocyanine green contrast-enhanced image). It may be. In addition, the spontaneous fluorescence image may be an image obtained by fluorescence emission of a fluorescent substance accumulated in the fundus Er, for example, an image obtained by fluorescence emission of lipofuscin.

  In the present embodiment, the laser light from the laser light source 11 passes through the opening formed in the perforated mirror 13, passes through the lens 14 and the lens 15, and then travels toward the scanning unit 16. The laser light reflected by the scanning unit 16 passes through the dichroic mirror 51, passes through the objective optical system 17, and then irradiates the fundus Er of the eye E to be examined. As a result, the laser light is reflected and scattered by the fundus oculi Er, or excites a fluorescent substance existing in the fundus oculi Er to generate fluorescence from the fundus oculi. These lights (that is, reflected / scattered light, fluorescence, etc.) are emitted from the pupil as light (return light) from the eye to be inspected upon irradiation with laser light.

  The scanning unit 16 (also referred to as “optical scanner”) is a unit for scanning the laser light emitted from the laser light source 11 on the fundus oculi Er. In the following description, it is assumed that the scanning unit 16 includes two optical scanners having different scanning directions of laser light unless otherwise specified. That is, an optical scanner 16a for main scanning (for example, scanning in the X direction) and an optical scanner 16b for sub-scanning (for example, scanning in the Y direction) are included. In the following description, it is assumed that the optical scanner 16a for main scanning is a resonant scanner, and the optical scanner 16b for sub scanning is a galvanometer mirror. However, other optical scanners may be applied to each of the optical scanners 16a and 16b. For example, for each of the optical scanners 16a and 16b, in addition to other reflecting mirrors (galvano mirror, polygon mirror, resonant scanner, MEMS, etc.), an acousto-optic device (AOM) that changes the traveling (deflection) direction of light, etc. May be applied.

  The objective optical system 17 is an objective optical system of the ophthalmologic photographing apparatus 1. The objective optical system 17 is used to irradiate the eye E with the laser light scanned by the scanning unit 16 and guide it to the fundus Er. For this purpose, the objective optical system 17 forms a turning point P around which the laser light passed through the scanning unit 16 is turned. The turning point P is formed on the reference optical axis L1 of the irradiation optical system 10 and at a position optically conjugate with the scanning unit 16 with respect to the objective optical system 17. In the present disclosure, “conjugate” is not necessarily limited to a complete conjugate relationship, and includes “substantially conjugate”. In other words, the case where the fundus image is arranged so as to deviate from the complete conjugate position within the range permitted in relation to the purpose of use of the fundus image (eg, observation, analysis, etc.) is also included in the “conjugate” in the present disclosure. In the present embodiment, the objective optical system 17 of the ophthalmologic photographing apparatus 1 is realized with only a lens, but is not necessarily limited thereto, and may be realized with a combination of a lens and a mirror.

  The laser beam that has passed through the scanning unit 16 passes through the objective optical system 17 and is irradiated to the fundus Er through the turning point P. For this reason, the laser light that has passed through the objective optical system 17 is turned around the turning point P as the scanning unit 16 operates. As a result, in the present embodiment, laser light is scanned two-dimensionally on the fundus Er. The laser light irradiated to the fundus Er is condensed at a condensing position (for example, the retina surface).

  Next, the light receiving optical system 20 will be described. The light receiving optical system 20 has at least one or a plurality of light receiving elements. For example, as shown in FIG. 1, the light receiving optical system 20 may include a plurality of light receiving elements 25, 27, and 29. In this case, the light from the fundus Er by the laser light irradiated by the irradiation optical system 10 is received by at least one of the light receiving elements 25, 27, and 29.

  As shown in FIG. 1, the light receiving optical system 20 in the present embodiment may share the members arranged from the objective optical system 17 to the perforated mirror 13 with the irradiation optical system 10. In this case, the light from the fundus Er is guided back to the perforated mirror 13 along the optical path of the irradiation optical system 10. The perforated mirror 13 removes at least a part of noise light due to reflection on the cornea of the eye E to be examined and an optical system inside the apparatus (for example, a lens surface of an objective lens system), and transmits light from the fundus Er. The light is guided to an independent optical path of the light receiving optical system 20.

  The optical path branching member that branches the irradiation optical system 10 and the light receiving optical system 20 is not limited to the perforated mirror 13, and other optical members (for example, a half mirror) may be used.

  The light receiving optical system 20 of the present embodiment includes a lens 21, a pinhole plate 23, and a light separation unit (light separation unit) 30 in the reflected light path of the perforated mirror 13.

  In the light receiving optical system 20 of this embodiment, the light path branching portions of the light projecting system and the light receiving system may be switched between the perforated mirror 13 and the dichroic mirror 45. The dichroic mirror 45 transmits excitation light (for example, blue light) in spontaneous fluorescence imaging (that is, allows it to pass to the eye side to be examined) and reflects spontaneous fluorescence from the fundus (that is, the light receiving elements 25, 27, and 29). To the side). For example, the dichroic mirror 45 is disposed in order to execute spontaneous fluorescence imaging in the case of the second angle of view (that is, when the lens attachment 3 is attached). When the shooting angle of view is widened, the fundus area of the eye E to be irradiated with the laser light is widened, so that the contrast of the fundus image is easily lowered. On the other hand, in the present embodiment, the signal efficiency can be improved by switching from the perforated mirror 13 to the dichroic mirror 45 when performing spontaneous fluorescence imaging. As a result, it is easy to improve the contrast in the spontaneous fluorescence image.

  The pinhole plate 23 is disposed on the fundus conjugate plane and functions as a confocal stop in the ophthalmologic photographing apparatus 1. That is, when the diopter is appropriately corrected by the diopter adjustment unit 40, the light from the fundus Er that has passed through the lens 21 is focused at the opening of the pinhole plate 23. The pinhole plate 23 removes light from a position other than the condensing point (or focal plane) of the fundus Er, and the rest (light from the condensing point) is directed to at least one of the light receiving elements 25, 27, and 29. Led.

  The aperture diameters of the aperture mirror 13 and the confocal aperture of the pinhole plate 23 may be switched in conjunction with the angle of view (that is, in conjunction with the attachment / detachment of the lens attachment 3).

  The light separation unit 30 separates light from the fundus Er. In the present embodiment, the light from the fundus Er is light-selectively separated by the light separation unit 30. The light separation unit 30 may also serve as a light branching unit that branches the optical path of the light receiving optical system 20. For example, as illustrated in FIG. 1, the light separation unit 30 may include two dichroic mirrors (dichroic filters) 31 and 32 having different light separation characteristics (wavelength separation characteristics). The optical path of the light receiving optical system 20 is branched into three by the two dichroic mirrors 31 and 32. Further, one of the light receiving elements 25, 27, and 29 is disposed at the tip of each branch optical path.

  For example, the light separation unit 30 separates the wavelength of light from the fundus Er and causes the three light receiving elements 25, 27, and 29 to receive light in different wavelength ranges. For example, the light receiving elements 25, 27, and 29 may receive light of three colors of blue, green, and red one by one. In this case, a color image may be acquired from the light reception results of the light receiving elements 25, 27, and 29.

  In addition, the light separation unit 30 may cause the fundus autofluorescence and the infrared light that is the fundus reflection light of the observation light to be received by different light receiving elements. Thereby, an infrared image may be captured simultaneously with the fluorescent image. In the present embodiment, blue light emitted from the laser light source 11 is used as excitation light of spontaneous fluorescence.

  Next, the alignment optical system 50 will be described. The alignment optical system 50 of the present embodiment includes, as an example, a dichroic mirror 51, a light source 52, a lens 53, and a light receiving element 55. The light source 52 has an alignment light source for emitting alignment light and an opening (not shown) that functions as a diaphragm. As an example, the light source 52 has two alignment light sources.

  The alignment light emitted from the alignment light source is reflected by the dichroic mirror 51 and is irradiated toward the eye E through the objective optical system. The alignment light reflected by the cornea of the eye E is reflected by the dichroic mirror 51 through the objective optical system and passes through the lens 53. The light that has passed through the lens 53 is received by the light receiving element 55. Based on the light reception result of the light receiving element 55, the alignment state of the eye E with respect to the objective optical system is detected. The signal output from the light receiving element 55 is input to the control unit 70 (see FIG. 9). The control unit 70 may generate an image indicating the alignment state of the eye E (hereinafter also referred to as “alignment image”) based on the input signal. The alignment image may be, for example, an image including an alignment index image indicating alignment light reflected by the cornea of the eye E.

  Here, the lens 53 is movable along the optical axis, thereby changing the focal length of the alignment optical system 50 and switching the magnification of the alignment index image. The ophthalmologic photographing apparatus 1 may be provided with a drive unit 53 a that moves the lens 53. The lens 53 is displaced according to the attachment / detachment of the lens attachment 3 (that is, according to the view angle switching).

  As the alignment optical system 50, an anterior ocular segment observation system that images the anterior ocular segment of the eye to be examined may be used. In addition, at least one of the light receiving elements 25, 27, and 29 may function as a part of the alignment detection unit. That is, at least one of the light receiving elements 25, 27, and 29 may be used in place of the light receiving element 55 to detect the alignment state. In this case, an optical system other than the alignment light source of the alignment optical system 50 may be omitted. For example, the control unit 70 may detect the alignment state based on a signal from at least one of the light receiving elements 25, 27, and 29.

  In the present embodiment, for example, the alignment state of the eye E with respect to the objective optical system is a shift amount of the position of the eye E with respect to the reference position with respect to the objective optical system. As described above, the turning point P of the laser beam is formed on the reference optical axis L1 of the irradiation optical system 10 and at a position optically conjugate with the scanning unit 16 with respect to the objective optical system 17. In the present embodiment, when the turning point P substantially coincides with the position of the pupil of the eye E, it is assumed that the eye E is aligned with the objective optical system. The position of the eye E to be examined when the alignment is correct becomes the reference position. For example, the amount of deviation of the position of the eye E with respect to the reference position may include the amount of deviation between the distance between the objective optical system and the reference position and the distance between the objective optical system and the eye E. For example, the alignment state of the eye E with respect to the objective optical system may include the distance between the eye E and the objective optical system in the direction of the reference optical axis L1 (Z direction). In this case, the amount of deviation between the eye E and the reference position in the direction of the reference optical axis L1 may be detected as the alignment state.

  As an example, the control unit 70 performs image processing on the alignment image, and quantifies the imaging state of the alignment index image (for example, at least one of the blur amount and the coordinate position), so that the reference optical axis L1 is detected. The distance (working distance) between the objective optical system and the eye E in the direction (Z direction) is detected. The control unit 70 detects the shift amount between the working distance and the distance from the objective optical system to the reference position as an alignment state. However, it is possible to change the method of detecting the alignment state. For example, in addition to the distance from the objective optical system to the eye E in the Z direction, the control unit 70 also determines the amount of deviation of the eye E in the direction (XY direction) intersecting the reference optical axis L1 in the alignment state. You may detect as.

  The working distance is defined as the distance between the eye E to be examined and the objective optical system of the ophthalmologic photographing apparatus 1. More specifically, it may be defined as the distance between the cornea surface of the eye E and the examination window of the ophthalmologic photographing apparatus 1 (for example, the lens surface closest to the eye E of the objective optical system).

  Note that the reference position with respect to the objective optical system (in this embodiment, an appropriate distance between the eye E to be examined and the objective optical system in the direction of the reference optical axis L1) depends on various imaging conditions (for example, imaging angle of view). May be different.

  Next, with reference to FIG. 2, an optical configuration in the case where the shooting field angle is the second field angle with a wider field angle will be described. In the present embodiment, the lens attachment 3 is disposed between the objective optical system 17 and the eye E to be examined, so that the objective optical system 18 for photographing at the second angle of view is configured. The lens attachment 3 of this embodiment has at least one lens. As shown in FIG. 2, the lens attachment 3 may have a plurality of lenses.

  The lens attachment 3 has positive power and is attached to the objective optical system 17 so that the shooting field angle is increased. On the other hand, since the magnification is reduced, if the positional relationship between the lens 53 and the light receiving element 55 is maintained before and after the attachment / detachment of the lens attachment 3, the alignment index image photographed by the light receiving element 55 is reduced. (FIG. 10 (a) → FIG. 10 (b)). Although details will be described later, in this embodiment, the lens 53 is displaced, and the distance between the focal point of the corneal reflected light of the index light beam and the light receiving surface of the light receiving element 55 is switched, thereby aligning based on the switching of the field angle of the photographing optical system. A change in the size of the index image is optically corrected.

  Next, the control system of the ophthalmologic photographing apparatus 1 will be described with reference to FIG. In the ophthalmologic photographing apparatus 1, each unit is controlled by the control unit 70. The control unit 70 is a processing device (processor) having an electronic circuit that performs control processing of each unit of the ophthalmologic photographing apparatus 1 and arithmetic processing. The control unit 70 is realized by a CPU (Central Processing Unit), a memory, and the like. The control unit 70 is electrically connected to the storage unit 71 via a bus or the like. Further, the control unit 70 includes the laser light source 11, the light receiving elements 25, 27, and 29, the scanning unit 16, the components of the alignment optical system 50 (specifically, the light source 52 and the light receiving element 55), the input interface 75, the monitor 80, and the like. These parts are also electrically connected.

  The storage unit 71 stores various control programs, fixed data, and the like. In the present embodiment, a shooting control program or the like is stored in the storage unit 71. The storage unit 71 may store temporary data or the like. An image obtained by the ophthalmologic photographing apparatus 1 may be stored in the storage unit 71. However, the image obtained by the ophthalmologic photographing apparatus 1 may be stored in an external storage device (for example, a storage device connected to the control unit 70 via LAN and WAN).

  For example, the control unit 70 forms a fundus image based on light reception signals output from the light receiving elements 25, 27, and 29. More specifically, the control unit 70 forms a fundus image in synchronization with the optical scanning performed by the scanning unit 16. For example, each time the sub-scanning optical scanner 16b reciprocates n times (n is an integer of 1 or more), the control unit 70 displays the fundus image of at least one frame (in other words, one sheet) (the light receiving element). Every time). In the following description, for the sake of convenience, one frame of the fundus image is formed for each round trip of the sub-scanning optical scanner 16b unless otherwise specified. In the present embodiment, since the three light receiving elements 25, 27, and 29 are provided, the control unit 70 uses a maximum of three types of images based on signals from the respective light receiving elements 25, 27, and 29 for sub-scanning. Is generated every time the optical scanner 16b reciprocates once.

  The control unit 70 may cause the monitor 80 to display a plurality of frames of fundus images sequentially formed based on the operation of the apparatus as described above as an observation image in time series. The observation image is a moving image composed of a fundus image acquired in substantially real time. Further, the control unit 70 captures (captures) a part of a plurality of fundus images that are sequentially formed as a captured image (capture image). At that time, the captured image is stored in a storage medium. The storage medium for storing the captured image may be a non-volatile storage medium (for example, a hard disk, a flash memory, etc.). In the present embodiment, for example, a fundus image formed at a predetermined timing (or period) is captured after outputting a trigger signal (for example, a release operation signal or the like).

  In addition, the control unit 70 controls the spectral characteristics in the spectroscopic unit 60 and the wavelength of light irradiated to the eye E. For example, in the present embodiment, the reflection imaging mode and the fluorescence imaging mode can be set by mode switching. For example, a color photographing mode can be set as the reflection photographing mode. In addition, as the fluorescence imaging mode, for example, an ICGA mode, an FA mode, and an FAF mode can be set. The wavelength of light emitted from the laser light source 11 is selected according to the set shooting mode.

  The input interface 75 is an operation unit that receives an examiner's operation. For example, a touch panel, a mouse, a keyboard, and the like may be used as the input interface 75. Such an input interface 75 may be a separate device from the ophthalmologic photographing apparatus 1. The control unit 70 may control each member described above based on an operation signal output from the input interface 75 (operation unit). For example, an operation for selecting a shooting mode or an operation for release may be input to the input interface 75.

<Shooting operation>
Next, the photographing operation of the ophthalmologic photographing apparatus 1 will be described. First, the examiner attaches / detaches the lens attachment 3 to / from the ophthalmic imaging apparatus 1 and sets the imaging angle of view of the ophthalmic imaging apparatus 1. The attachment / detachment state of the lens attachment 3 may be manually input to the ophthalmologic photographing apparatus 1 by the examiner. In addition, a sensor that detects the attachment / detachment state of the lens attachment 3 may be provided in the ophthalmologic photographing apparatus 1, and a detection signal from the sensor may be input to the ophthalmic photographing apparatus 1.

  The control unit 70 of the present embodiment can set the photographing mode of the ophthalmologic photographing apparatus 1 by selecting one of the reflective photographing mode and the fluorescent photographing mode. For example, any one of ICGA mode, FA mode, and FAF mode may be selectable as the fluorescence imaging mode. Here, as an example, a case where shooting is performed in the reflection shooting mode will be described.

  The imaging mode may be set based on the examiner's operation. For example, the control unit 70 may automatically switch the shooting mode after shooting in each shooting mode in a predetermined order.

  In the reflection imaging mode of the present embodiment, a color fundus image is captured by fundus reflection light. In the reflection photographing mode, the control unit 70 causes the laser light source 11 to emit light in the red, green, and blue wavelength ranges at the same time. As a result, the red component is received by the light receiving element 25, the green component is received by the light receiving element 27, and the blue component is received by the light receiving element 29. The control unit 70 processes signals from the respective light receiving elements 25, 27, and 29 to form a fundus image in color. Then, after forming three types of fundus images corresponding to the red, green, and blue components, they may be combined into one to form a color fundus image.

  Note that the reflection photographing mode may be a photographing mode in which an infrared image using near infrared light is photographed instead of a color image.

  The ophthalmologic photographing apparatus 1 may photograph a reflection image simultaneously with each fluorescent image. The reflection image can also be used for associating the positional relationship between the respective fluorescent images photographed continuously.

  Next, a specific example of the apparatus operation in the fluorescence imaging mode will be described. First, the examiner sets imaging conditions including an imaging mode and aligns the objective optical system with respect to the eye E.

  At the time of alignment, the examiner fixes the subject's face to the face support unit (not shown) of the ophthalmologic photographing apparatus 1. Further, the eye E is fixed by a fixation target projection unit (not shown) of the ophthalmologic photographing apparatus 1.

  Further, the control unit 70 emits alignment light from the alignment light source 52 of the alignment optical system 50. In the present embodiment, an alignment image of the eye E to be obtained that is acquired using the light receiving element 55 is used for alignment. For example, the examiner may observe the alignment index image included in the alignment image displayed on the monitor 80 and perform manual alignment on the eye E.

  When the lens attachment 3 is not attached (that is, at the first angle of view), the control unit 70 sets the distance between the focal point of the corneal reflected light of the index light beam and the light receiving surface of the light receiving element 55 as the first distance. Set to. On the other hand, when the lens attachment 3 is attached (that is, in the case of the second angle of view), the control unit 70 sets the distance between the focal point of the corneal reflected light of the index light beam and the light receiving surface of the light receiving element 55 as a first value. A second distance that is greater than the distance is set. Thereby, in the case of the second angle of view, the reduction of the alignment index image is suppressed. The distance between the focal point and the light receiving surface of the light receiving element 55 may be controlled based on the detection result of the lens attachment 3.

  For example, the examiner may adjust the distance between the objective optical system and the eye E to be an appropriate working distance with reference to the imaging state of the alignment index image. The examiner performs alignment by moving an imaging unit (not shown) supporting the objective optical system back and forth so that the alignment index image is in focus.

  Further, the examiner may perform alignment in the vertical and horizontal directions of the objective optical system with respect to the eye E with reference to the formation position of the alignment index image. The examiner performs alignment by moving the imaging unit in the vertical and horizontal directions so that the alignment index image is formed at a predetermined position.

  As a result, in either case of the first field angle or the second field angle, it is possible to lead to an appropriate alignment state, and as a result, it is possible to photograph the fundus satisfactorily while suppressing vignetting of the photographing light.

  The control unit 70 controls each unit of the ophthalmologic photographing apparatus 1 and is based on emission of laser light from the laser light source 11, driving of the scanning unit 16, and a light reception signal from at least one of the light receiving elements 25, 27, and 29. A front image of the eye E is generated and displayed.

  Various modifications can be made to the above embodiment.

  For example, in <Example>, in order to obtain an alignment index image having an appropriate size in each of the first angle of view and the second angle of view, the alignment is performed in conjunction with the switching of the angle of view. Although the case of switching the focal position in the optical system 50 has been described, the present invention is not necessarily limited to this. For example, in the case of the second angle of view, an alignment index image (sometimes referred to as a multiple reflection image) based on the multiple reflected light of the observation light, with the lens surface included in the lens attachment 3 being at least a reflective surface. You may make it obtain (refer FIG. 6). For example, in this modification, as shown in FIG. 6, a part of the observation light reflected in the order of the lens surface 332a of the lens 332 → the lens surface 331a of the lens 331 is projected onto the cornea. The light projected at this time is used as an index light beam, and further, the corneal reflection light (that is, multiple reflected light) of the index light beam is used as an alignment index image. Since the alignment index image is superimposed and displayed on the fundus observation image, alignment adjustment can be performed while confirming the fundus observation image. The lens surfaces 331a and 332a may be provided with a coating that increases the reflectance of the infrared light that is the observation light with respect to the visible light that is the photographing light. It is possible to suppress the reflection of the index image while forming the index image.

  As described above, the alignment index image in the alignment optical system 50 is reduced at the second angle of view compared to the case of the first angle of view, but may be used together with multiple reflected light during alignment. Good. That is, in the case of the second angle of view, first, using the index image by the alignment optical system 50, the alignment is roughly adjusted until the index image by the multiple reflected light can be confirmed on the observation image, and then Further, more detailed alignment adjustment may be performed using an index image by multiple reflected light.

  In addition, when the control unit performs alignment state detection processing and induces alignment based on the detection result, the control unit switches the alignment detection processing between the first field angle and the second field angle. Also good. In this case, for example, the index images detected in the detection process may be different between the first field angle and the second field angle. Further, of the first angle of view and the second angle of view, the alignment state may be detected using the index image, and on the other hand, the alignment state may be detected without using the index image. As a method for detecting the alignment state without using the index image, for example, it may be based on pupil detection in the anterior ocular segment observation image, or may be based on another method. Further, although the index image detected in the detection process is common between the first angle of view and the second angle of view, the detection conditions may be different from each other. The detection condition may be a luminance threshold value for detecting the index image, a detection range, or other conditions.

  Thus, before and after switching between the first angle of view and the second angle of view, the control unit may switch the method for detecting the alignment state. In the switching of the detection method, for example, in one case of the first field angle and the second field angle, the alignment state is detected based on the alignment index image projected onto the cornea, and in the other case, the alignment state is detected. What does not perform detection of may be included.

  As the ophthalmologic photographing apparatus 1, an ophthalmologic photographing apparatus (for example, an OCT apparatus, a fundus camera, etc.) other than SLO may be used. The ophthalmologic imaging apparatus 1 may include a plurality of imaging units (for example, an SLO unit and an OCT apparatus unit) that capture different images.

  In addition, the present disclosure includes the following problem solving means. For example, the first ophthalmologic apparatus irradiates light to the eye to be examined via an objective optical system including one or a plurality of lenses, and takes or measures the eye to be examined based on return light from the eye to be examined. System, alignment adjusting means for adjusting the positional relationship between the first optical system and the eye to be examined, and a predetermined light receiving surface when the working distance between the eye to be examined and the first optical system is a predetermined distance. An alignment index image formed by multiple reflected light of the light that is reflected at least once by the lens surface included in the objective optical system and then reflected by the cornea of the eye to be examined. And a light receiving element for imaging.

  According to the first ophthalmologic apparatus, the alignment index image is formed by the multiple reflected light of the light irradiated for photographing the fundus, so that the optical system that projects or images the alignment index on the eye to be examined The alignment state can be adjusted using the alignment index image.

  The second ophthalmologic apparatus is a first ophthalmologic apparatus, and the objective optical system has a coaxial lens coaxial with the optical axis of the first optical system, and is reflected by the lens surface of the coaxial lens. The alignment index image is formed by the light.

  In the coaxial lens, the region near the optical axis is parallel to the cornea of the eye to be examined or another coaxial lens, so that multiple reflected light tends to be easily generated.

  The third ophthalmologic apparatus is the first or second ophthalmologic apparatus, and includes an attachment optical system that is inserted into and removed from the objective optical system in order to change the optical power of the objective optical system, and the attachment The alignment index image is formed by the light reflected by the lens surface of the lens included in the optical system.

  The fourth ophthalmologic apparatus is any one of the first to third ophthalmologic apparatuses, and the lens surface further reflects light reflected by another lens surface or cornea and guides it to the cornea of the eye to be examined.

  The first to fourth ophthalmologic apparatuses to the fourth ophthalmologic apparatus are not necessarily limited to the fundus imaging apparatus shown in the above embodiment, and may be applied to various ophthalmologic imaging apparatuses. Further, the present invention is not limited to an ophthalmologic photographing apparatus, and may be applied to an ophthalmologic measurement apparatus that measures the eye characteristics of an eye to be examined.

DESCRIPTION OF SYMBOLS 1 Fundus photography apparatus 3 Lens attachment 10 Light projection optical system 20 Light reception optical system 17 Objective lens 50 Alignment optical system 53 Lens 70 Control part

Claims (7)

An imaging optical system that irradiates light to the fundus of the subject's eye via the objective optical system, and images the fundus of the subject's eye based on return light from the fundus,
At least the objective optical system is shared with the imaging optical system, and an alignment optical system having a light receiving element that captures an alignment index image based on the corneal reflected light of the index beam projected onto the eye to be examined;
Alignment adjusting means for adjusting the positional relationship between the imaging optical system and the eye to be examined;
An angle-of-view switching means for switching an angle of view in the photographing optical system by switching at least the objective optical system;
A fundus photographing apparatus comprising: a correction unit that optically corrects a change in the size of the alignment index image based on a field angle switching of the photographing optical system.   The fundus imaging according to claim 1, wherein the alignment optical system forms the alignment index image on a light receiving surface of the light receiving element when a working distance between the eye to be examined and the fundus photographing apparatus is a predetermined distance. apparatus.   The correction means has switching means for changing the distance between the focal point of the corneal reflected light and the light receiving surface of the light receiving element in an optical path independent of the imaging optical system in the alignment optical system, and the distance is the imaging The fundus imaging apparatus according to claim 1 or 2, wherein a change in the size of the alignment index image is corrected by changing the angle of view according to the angle of view of the optical system. The field angle switching means switches the field angle between a first field angle and a second field angle larger than the first field angle.
The correction means includes a first region having a first focal length corresponding to the first angle of view and a second region having a second focal length corresponding to the second angle of view, and corresponds to the first region. The fundus imaging apparatus according to claim 1, further comprising a multifocal optical element that simultaneously forms a cornea reflection image and a cornea reflection image corresponding to the second region.   The correction unit includes an optical path branching unit that branches an optical path between the light receiving element and the correction member into a plurality of optical paths having different distances between the focal point of the corneal reflected light and the light receiving surface of the light receiving element. The fundus imaging apparatus according to claim 1 or 2.   The correction means includes a light beam diameter changing means for changing a light beam diameter of the index light beam projected on the eye to be examined, and the alignment is performed by changing the light beam diameter in accordance with a change of an angle of view of the photographing optical system. The fundus imaging apparatus according to claim 1, wherein a change in the size of the index image is corrected. The fundus imaging apparatus according to any one of claims 1 to 6, wherein the angle-of-view switching unit is an attachment optical system that includes at least an optical element for switching the objective optical system and is detachable from the apparatus main body.