JP2020022569A - Fundus imaging device, fundus imaging method and program - Google Patents

Abstract

To correct chromatic aberration of an eye to be examined in a configuration having an OCT optical system and an SLO optical system.SOLUTION: According to the present invention, a fundus imaging device includes: an OCT optical system for using OCT measuring light to acquire tomographic information of an eye to be examined; an SLO optical system for using SLO measuring light to acquire fundus information of the eye to be examined; a common optical path sharing at least of a portion of an optical path of the OCT measuring light and an optical path of the SLO measuring light; and chromatic aberration correction means provided in the optical path of the OCT measuring light branched from the common optical path to correct chromatic aberration in the eye to be examined.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fundus imaging device, a fundus imaging method, and a program.

2. Description of the Related Art In recent years, as an ophthalmic apparatus, an apparatus that scans a fundus by scanning illumination light, such as an OCT (Optical Coherence Tomography) apparatus and an SLO (Scanning Laser Ophthalmoscope) apparatus, has been widely used.
Patent Literature 1 proposes an ophthalmologic apparatus configured by combining an OCT apparatus and an SLO apparatus. According to such an ophthalmologic apparatus, a fundus tomographic image and a fundus plane image can be acquired by one examination, and the examination can be made more efficient.

  By the way, in the OCT apparatus, the resolution in the depth direction is improved as the wavelength band of the measurement light is wider. However, when the wavelength band is widened, the difference in the focal position on the fundus according to the wavelength of the measurement light increases due to the chromatic aberration of the eye to be examined and the optical system of the apparatus. In particular, when the depth of focus is small in the adaptive optics OCT apparatus, the influence of the difference in the focal position due to chromatic aberration on the image quality of the fundus image cannot be ignored. Therefore, in order to obtain a high-resolution and high-quality fundus image using the adaptive optics OCT apparatus, it is important to correct the chromatic aberration of the eye to be inspected and the optical system of the apparatus.

  To solve such a problem, Patent Literature 2 proposes an ophthalmologic apparatus including a lens that corrects chromatic aberration of an eye to be inspected. In the ophthalmologic apparatus of Patent Literature 2, a configuration is disclosed in which a lens intentionally made to have a chromatic aberration opposite to the chromatic aberration of the subject's eye is disposed immediately in front of the subject's eye.

JP-A-2005-221091 JP-T-2007-521866

  However, in the configuration in which the lens for correcting the chromatic aberration disclosed in Patent Document 2 is disposed immediately in front of the eye to be examined, the configuration is applied to a configuration in which a plurality of optical systems such as the OCT optical system and the SLO optical system as in Patent Document 1 are combined. In that case, a new problem arises. Specifically, since the OCT optical system and the SLO optical system have different wavelength bands, correcting the chromatic aberration in all the wavelength bands complicates the lens configuration. Further, when the lens is configured to correct the chromatic aberration only in the wavelength band of the OCT optical system, the optical performance of another optical system such as the SLO optical system may be adversely affected.

  The present invention has been made in view of the above-described problems, and has as its object to correct chromatic aberration of an eye to be inspected in a configuration having an OCT optical system and an SLO optical system.

  A fundus imaging apparatus according to an aspect of the invention includes an OCT optical system that acquires tomographic information of the subject's eye using OCT measurement light, an SLO optical system that acquires fundus information of the subject's eye using SLO measurement light, and the OCT measurement. A common optical path that shares at least a part of the optical path of the light and the optical path of the SLO measurement light, and a chromatic aberration correction unit that is provided in the optical path of the OCT measurement light branched from the common optical path and corrects chromatic aberration in the subject's eye. , Is characterized by having.

  According to the present invention, chromatic aberration of an eye to be inspected can be corrected in a configuration having an OCT optical system and an SLO optical system.

FIG. 1 is a diagram illustrating an example of a configuration of a fundus imaging device according to a first embodiment. FIG. 2 is a diagram schematically illustrating an imaging range of an OCT optical system and an SLO optical system. 5 is a flowchart illustrating an example of a procedure for photographing a fundus of the first embodiment. It is a figure showing an example of composition of a fundus imaging device of a 2nd embodiment. It is a flow chart which shows an example of a photography procedure of a fundus of a 2nd embodiment.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. However, dimensions, materials, shapes, relative positions of components, and the like described in the following embodiments are arbitrary, and can be changed according to the configuration of an apparatus to which the present invention is applied or various conditions.
In the following, the retina of the human eye is used as the object to be inspected, but the object to be inspected is not limited to this.

<First embodiment>
The fundus imaging apparatus 100 according to the first embodiment of the present invention, which is used for acquiring an image of the fundus of the subject's eye and the like, will be described with reference to FIGS.
(Device configuration)
FIG. 1 is a diagram illustrating an example of the configuration of the fundus imaging device 100.
The fundus imaging apparatus 100 includes an OCT optical system, an SLO optical system, an anterior eye observation optical system, a fixation light optical system, and a control unit 190 (control means). In the present embodiment, the entire optical system is mainly configured by a reflection optical system using a mirror.
The control unit 190 may be configured using a general-purpose computer, or may be configured as a computer dedicated to the fundus imaging apparatus 100. The control unit 190 may be configured separately from the imaging unit including the OCT optical system, the SLO optical system, the anterior eye observation optical system, and the fixation lamp optical system, or may be configured integrally.

First, the OCT optical system of the fundus imaging device 100 will be described.
The light source 101 is a light source for generating light (low coherent light). The light source 101 corresponds to an example of an OCT light source. In the present embodiment, an SLD (Super Luminescent Diode) having a center wavelength of 830 nm and a band of 50 nm is used as the light source 101. However, the light source 101 is not limited to an SLD, and may be any light source that can emit low coherent light, and may use ASE (Amplified Spontaneous Emission) or the like. The light source 101 is connected to the control unit 190 and is controlled by the control unit 190.

  The wavelength of the light emitted from the light source 101 can be a wavelength corresponding to the near-infrared light in consideration of measuring the eye. Further, the wavelength of the light emitted from the light source 101 affects the horizontal resolution of the obtained tomographic image, and thus can be as short as possible. In this embodiment, the center wavelength is 830 nm. However, another wavelength may be selected depending on the measurement site to be observed. Note that the wider the wavelength band, the better the resolution in the depth direction. Generally, when the center wavelength is 830 nm, the resolution is 6 μm in the 50 nm band, and 3 μm in the 100 nm band. However, the center wavelength and band of the light source 101 are not limited to this case, and can be changed according to a desired configuration.

  Light emitted from the light source 101 is guided to the optical coupler 141 through the single mode fiber 142. The optical coupler 141 corresponds to an example of a dividing unit. Light emitted from the light source 101 is split by the optical coupler 141 at an intensity ratio of 90:10, and becomes a reference light 103 and an OCT measurement light 104, respectively. However, the division ratio is not limited to this case, and can be appropriately selected according to the inspection object.

  Next, the optical path of the reference light 103 will be described. The reference light 103 split by the optical coupler 141 passes through the single mode fiber 143, is guided to the lens 151, and is emitted as parallel light. Next, the reference light 103 passes through the dispersion compensating glass 159, and is guided by the mirrors 111 and 112 to a mirror 124 that is a reference mirror. In the present embodiment, a plane mirror is used as a reference mirror. The light reflected by the mirror 124 is again reflected by the mirror 112 and the mirror 111 again, passes through the dispersion compensating glass 159, and is guided to the optical coupler 141.

The dispersion compensating glass 159 can compensate the dispersion of the reference light 103 when the OCT measuring light 104 reciprocates between the eye E and the lenses 154 and 11.
The mirror 124 constitutes an optical path length adjusting means by being mounted on the electric stage 125. The electric stage 125 is movable in the optical axis direction of the reference light 103 as shown by the arrow. By moving the motorized stage 125, the position of the mirror 124 can be moved, and the optical path length of the reference light 103 can be adjusted. The electric stage 125 is controlled by the control unit 190.

  Next, the optical path of the OCT measurement light 104 will be described. The OCT measurement light 104 split by the optical coupler 141 passes through the single mode fiber 145, is guided to the lens 154, and is emitted as parallel light. The lens 154 corresponds to an example of a second optical unit. The OCT measurement light 104 emitted as parallel light passes through the chromatic aberration correction lens 10. The chromatic aberration correcting lens 10 corresponds to an example of a chromatic aberration correcting unit.

  The chromatic aberration correcting lens 10 is a cemented lens in which a plano-convex lens 10a and a plano-concave lens 10b are cemented in the order in which the OCT measurement light 104 is transmitted, and causes chromatic aberration reverse to that of the eye E to cancel the chromatic aberration of the eye E. ing. Here, in the chromatic aberration correcting lens 10, the plano-convex lens 10a is made of a lower dispersion glass type, the plano-concave lens 10b is made of a higher dispersion glass type, and the refractive index of the plano-convex lens 10a is substantially equal to that of the plano-concave lens 10b. By using such a shape and glass type, only the chromatic aberration can be corrected without affecting the arrangement of other optical elements of the optical system and other aberrations. However, the configuration of the chromatic aberration correction lens 10 is not limited to this, and may be, for example, a cemented lens in which a plano-concave lens and a plano-convex lens are cemented in the order in which the OCT measurement light 104 is transmitted. Further, a biconvex lens, a biconcave lens, or a cemented lens of a meniscus lens may be used. In this case, the configuration may be such that the OCT measurement light 104 is emitted as parallel light by the combined refractive power of the lens 154 and the chromatic aberration correction lens 10. Further, a cemented lens of three or more lenses such as a plano-concave lens, a biconvex lens, and a plano-concave lens may be used. In this case, one chromatic aberration correcting lens can correct a larger amount of chromatic aberration. Further, two or more chromatic aberration correcting lenses may be arranged in the optical path. In this case, a larger amount of chromatic aberration can be corrected.

  Here, the chromatic aberration correction lens 10 of the present embodiment is disposed on a dedicated optical path of the OCT measurement light branched from a common optical path of the optical path of the OCT measurement light and the optical path of the SLO measurement light. Since different wavelengths are used for the SLO measurement light and the OCT measurement light, the influence of the chromatic aberration of the eye E is different. Further, in the OCT optical system, the wavelength band is widened in order to increase the resolution in the depth direction, so that the chromatic aberration of the eye E to be examined is more affected than in the SLO optical system. Therefore, by disposing the chromatic aberration correcting lens 10 in the optical path of the OCT measurement light, it is possible to suppress the influence of the chromatic aberration of the eye E on the OCT optical system without affecting the optical performance of the SLO optical system. .

Next, the OCT measurement light 104 is emitted toward the dichroic mirror 177 and passes through the dichroic mirror 177. The dichroic mirror 177 transmits or reflects light according to the wavelength of the light. The dichroic mirror 177 is an example of a light guiding unit that guides the OCT measurement light 104 and the SLO measurement light 106 to a common optical path. The dichroic mirror 177 corresponds to an example of a first optical unit that transmits the OCT measurement light 104 and reflects the SLO measurement light 106 to guide the OCT measurement light 104 to a common optical path.
The OCT measurement light 104 transmitted through the dichroic mirror 177 transmits through the beam splitter 171, is reflected by the mirrors 113 and 114, and enters the deformable mirror 182. The deformable mirror 182 is a mirror device, and corresponds to an example of an aberration correcting unit. The deformable mirror 182 corrects the aberration between the OCT measurement light 104 and the OCT return light 105 by freely deforming the mirror shape based on the aberration detected by the wavefront sensor 181. The wavefront sensor 181 corresponds to an example of an aberration measuring unit. As the wavefront sensor 181, for example, a Shack-Hartmann wavefront sensor can be used.
The correction of the aberration is not limited to the case where the deformable mirror 182 is used, and for example, a spatial light phase modulator using liquid crystal may be used. Further, the measurement of aberration is not limited to the case where the wavefront sensor 181 is used, and for example, any known sensor or the like may be used. The deformable mirror 182 and the wavefront sensor 181 are controlled by the control unit 190.

After being reflected by the deformable mirror 182, the OCT measurement light 104 is reflected by the mirrors 115 and 116 and enters the dichroic mirror 173. Here, the dichroic mirrors 173 and 174 reflect the light from the light source 101 and transmit the light from the light source 102 according to the wavelength of the light.
The OCT measurement light 104 reflected by the dichroic mirror 173 enters the X scanner 132. The X scanner 132 corresponds to an example of a second scanning unit. As the X scanner 132, for example, a galvanometer mirror can be used. The center of the OCT measurement light 104 is adjusted to coincide with the rotation center of the X scanner 132. By rotating the X scanner 132, the OCT measurement light 104 can be used to scan the retina Er of the eye E in a direction perpendicular to the optical axis. Note that the X scanner 132 may be configured by, for example, any other deflecting mirror. The X scanner 132 is connected to the control unit 190 and is controlled by the control unit 190.

The OCT measurement light 104 reflected by the X scanner 132 is reflected by the dichroic mirror 174 and then sequentially reflected by the mirrors 117 to 120.
The mirrors 119 and 120 constitute first focusing means when mounted on the electric stage 126. The electric stage 126 is movable in a direction approaching or moving away from the mirrors 118 and 121 as shown by arrows. The electric stage 126 is controlled by the control unit 190. The mirrors 119 and 120 are arranged on a common optical path of the OCT optical system and the SLO optical system. Therefore, by moving the electric stage 126, the mirrors 119 and 120 can be moved, and the focus state of the OCT measurement light 104 and the SLO measurement light 106 can be adjusted according to the diopter of the eye E to be inspected.

In the present embodiment, the movement range of the electric stage 126 is 160 mm, and the focus positions of the OCT measurement light 104 and the SLO measurement light 106 can be adjusted according to the diopter range of −12D to + 7D of the eye E. . The moving range of the electric stage 126 may be set arbitrarily according to a desired configuration.
Further, in the present embodiment, the mirrors 119 and 120 as the first focus unit are configured by a Badal optical system using a reflection optical system. By using the reflection optical system, unnecessary stray light can be prevented from entering the wavefront sensor 181, and accurate aberration measurement and aberration correction can be performed.

The OCT measurement light 104 reflected by the mirror 120 is reflected by the mirrors 121 and 122, enters the lens 11, and enters the Y scanner 133. The Y scanner 133 corresponds to an example of a first scanning unit. As the Y scanner 133, for example, a galvanometer mirror can be used. Here, the lens 11 has a positive refractive power, and causes the light beam scanned by the X scanner 132 to enter the Y scanner 133 in a wider incident angle range. Therefore, the swing angle of the X scanner 132 can be reduced, and the optical system between the X scanner 132 and the Y scanner 133 can be prevented from increasing in size.
In addition, since it is easy to increase the magnification of imaging on the pupil Ep optically conjugate with the Y scanner 133 while securing the scanning range on the retina Er, the distance between the apparatus and the eye E to be inspected (working distance) It will be advantageous to secure. The chromatic aberration correcting lens 10 described above may correct the chromatic aberration of the lens 11 in addition to the chromatic aberration of the eye E. This makes it possible to reduce the difference in focal position according to the wavelength on the fundus, which is advantageous for obtaining a high-resolution and high-quality fundus tomographic image. That is, the chromatic aberration correction lens 10 is configured to align the focus position on the fundus with respect to the wavelength band of the OCT measurement light.

The center of the OCT measurement light 104 is adjusted to coincide with the rotation center of the Y scanner 133. By rotating the Y scanner 133, the OCT measurement light 104 can be used to scan the retina Er in a direction perpendicular to the optical axis and the scan direction of the X scanner 132. Note that the Y scanner 133 may be constituted by any other deflecting mirror. The Y scanner 133 is connected to the control unit 190 and is controlled by the control unit 190.
The X scanner 132 and the Y scanner 133 correspond to an example of an OCT scanning unit that scans the OCT measuring beam 104 on the fundus of the eye E in a two-dimensional direction.

The OCT measurement light 104 reflected by the Y scanner 133 is reflected by the mirror 123, passes through dichroic mirrors 175 and 176, and enters the eye E. The X scanner 132, the Y scanner 133, and the mirrors 117 to 123 function as an OCT optical system for scanning the retina Er using the OCT measurement light 104. With this optical system, the retina Er can be scanned using the OCT measurement light 104 around the pupil Ep as a fulcrum.
When the OCT measurement light 104 is incident on the eye E, the OCT measurement light 104 is reflected or scattered by the retina Er, returns to the optical path of the OCT measurement light 104 as the OCT return light 105, and is guided again to the optical coupler 141.

  The reference light 103 and the OCT return light 105 are multiplexed by the optical coupler 141 to become interference light. Here, when the optical path lengths of the OCT measurement light 104 and the OCT return light 105 are substantially equal to the optical path length of the reference light 103, the OCT return light 105 and the reference light 103 interfere with each other and become interference light. . The control unit 190 controls the motorized stage 125 to move the mirror 124 so that the optical path length of the reference light 103 matches the optical path length of the OCT measurement light 104 and the OCT return light 105 that change depending on the measurement target of the eye E. Can be. The multiplexed light 108 (interference light) is emitted as spatial light from the single mode fiber 144, and is guided to the transmission grating 161 through the lens 152. Thereafter, the light 108 is split by the transmission grating 161 for each wavelength, collected by the lens 153, and incident on the line camera 191.

  The light 108 incident on the line camera 191 is converted into a voltage signal (interference signal) corresponding to the light intensity for each position (wavelength) on the line camera 191. Specifically, interference fringes in the spectral region on the wavelength axis are observed on the line camera 191. The obtained voltage signal group is converted into a digital value. The control unit 190 can generate a tomographic image of the eye E by performing data processing on the interference signal converted into the digital value. Known data processing for generating a tomographic image from an interference signal can be used for data processing when generating a tomographic image. The control unit 190 displays the generated tomographic image on a display unit (not shown). For the display unit, for example, an arbitrary monitor can be used. Further, the display unit may be separate from the imaging unit and the control unit 190, or may be configured integrally.

  The single mode fibers 142 and 143 are provided with polarization adjustment paddles 183 and 184, respectively. The polarization adjusting paddles 183, 184 can adjust the polarization of light passing through the single mode fibers 142, 143. By using the polarization adjustment paddles 183 and 184, the polarization state of the light from the light source 101 is adjusted, and the polarization of the reference light 103 is adjusted so that the polarization states of the OCT return light 105 and the reference light 103 match. Or you can. The positions at which the polarization adjusting paddles 183 and 184 are provided are not limited to this case, and may be provided at the single mode fiber 145 or the like.

  Meanwhile, when returning the OCT return light 105 along the optical path of the OCT measurement light 104, the OCT return light 105 is split by the beam splitter 171 and a part of the split light enters the wavefront sensor 181. The wavefront sensor 181 measures the aberration of the incident OCT return light 105. In the present embodiment, the beam splitter 171 reflects a part of the OCT return light 105 and transmits an SLO return light 107 described later. Therefore, the wavefront sensor 181 can selectively measure the aberration of the OCT return light 105. The wavefront sensor 181 is electrically connected to the control unit 190.

  The control unit 190 grasps the aberration of the eye E measured by the wavefront sensor 181 by applying the output from the wavefront sensor 181 to the Zernike polynomial. The control unit 190 corrects the diopter of the eye E by controlling the positions of the mirrors 119 and 120 using the electric stage 126 for the defocus component of the Zernike polynomial. The control unit 190 controls and corrects the surface shape of the deformable mirror 182 for components other than defocus. Therefore, the control unit 190 can generate (acquire) a tomographic image with high lateral resolution.

  Here, mirrors 113 to 123 are arranged such that pupil Ep, X scanner 132, Y scanner 133, wavefront sensor 181, and deformable mirror 182 are optically conjugate. Thereby, the wavefront sensor 181 can measure the aberration of the eye E.

Next, the SLO optical system will be described.
The light source 102 generates light having a wavelength different from that of the light source 101. The light source 102 corresponds to an example of an SLO light source. In this embodiment, an SLD having a wavelength of 780 nm is used as the light source 102. However, the light source 102 is not limited to an SLD, and may be an LD (Laser Diode) or the like. Further, the wavelength of the light source 102 is not limited to this case, and may be changed according to a desired configuration. The light source 102 is connected to the control unit 190 and is controlled by the control unit 190.

  The light emitted from the light source 102 is guided to the lens 155 and emitted as parallel light. The light transmitted through the lens 155 is guided to the beam splitter 172, where the transmitted light and the reflected light (SLO measurement light 106) have an intensity ratio of 90:10. The SLO measurement light 106 reflected by the beam splitter 172 passes through the focus lens 157 and the lens 158.

The focus lens 157 forms a second focus unit by being mounted on the electric stage 127. The electric stage 127 is movable in the optical axis direction of the SLO measurement light 106 as shown by the arrow. The electric stage 127 is controlled by the control unit 190. The focus lens 157 is arranged not on a common optical path of the OCT optical system and the SLO optical system but on a dedicated optical path of the SLO optical system. Therefore, by moving the electric stage 127, the focus lens 157 moves, and the focus state of the SLO measurement light 106 can be adjusted.
That is, the control unit 190 can adjust the focus position of the SLO measurement light 106 to a predetermined position different from the focus position of the OCT measurement light 104 by moving the focus lens 157 by controlling the electric stage 127.

In the present embodiment, the moving range of the electric stage 127 is 10 mm, and the moving range corresponds to a diopter range of −2D to + 2D. The moving range of the electric stage 127 is not limited to this case, and can be set to an arbitrary moving range narrower than the moving range of the electric stage 126.
In the present embodiment, in order to perform focus adjustment of the OCT measurement light 104 and the SLO measurement light 106 using the first focus means and correct the diopter of the eye E to be inspected, the focus adjustment range of the second focus means is narrowed. Can be suppressed. That is, the moving range of the electric stage 127 can be smaller than the moving range of the electric stage 126. Therefore, since a small stage can be used to adjust the focal positions of the OCT optical system and the SLO optical system to different positions, the optical system can be downsized.

  Although the focus lens 157 is a convex lens and the lens 158 is a concave lens in FIG. 1, the configurations of the focus lens 157 and the lens 158 are not limited to this case. For example, the focus lens 157 may be a concave lens, the lens 158 may be a convex lens, or both may be convex lenses, and an intermediate image may be formed therebetween.

  The light transmitted through the focus lens 157 and the lens 158 is emitted toward the dichroic mirror 177 and is reflected by the dichroic mirror 177. The SLO measurement light 106 reflected by the dichroic mirror 177 enters the dichroic mirror 173 through a common optical path with the OCT measurement light 104. Here, the common optical path of the SLO measurement light 106 and the OCT measurement light 104 includes an optical path passing through the dichroic mirror 177, the beam splitter 171, the mirrors 113 and 114, the deformable mirror 182, the mirrors 115 and 116, and the dichroic mirror 173. .

The dichroic mirrors 173 and 174 reflect the light from the light source 101 and transmit the light from the light source 102 according to the wavelength of the light. Therefore, the SLO measurement light 106 reflected by the mirror 116 passes through the dichroic mirror 173 and enters the X scanner 131. The X scanner 131 corresponds to an example of a third scanning unit. As the X scanner 131, for example, a resonance mirror can be used. The center of the SLO measurement light 106 is adjusted to coincide with the rotation center of the X scanner 131. By rotating the X scanner 131, the retina Er can be scanned in a direction perpendicular to the optical axis using the SLO measurement light 106. The X scanner 131 is connected to the control unit 190 and is controlled by the control unit 190.
The X scanner 131 and the Y scanner 133 correspond to an example of an SLO scanning unit that scans the SLO measurement light 106 on the fundus of the eye E in a two-dimensional direction.

  In this embodiment, the optical path of the OCT measurement light 104 and the optical path of the SLO measurement light 106 are branched by the dichroic mirror 173, and the X scanner 132 of the OCT measurement light 104 and the X scanner 131 of the SLO measurement light 106 are arranged at different positions. It is. The scanning speed of the OCT measuring light 104 is limited by the reading speed of the line camera 191. On the other hand, by setting the X scanner 132 of the OCT measuring beam 104 and the X scanner 131 of the SLO measuring beam 106 at different positions, the scan speed of the SLO measuring beam 106 does not depend on the OCT scan speed. Can be raised. Therefore, it is possible to improve the frame rate when acquiring a fundus oculi planar image using the SLO optical system. Note that the X scanner 131 may be configured by an arbitrary deflection mirror according to a desired configuration.

The SLO measurement light 106 reflected by the X scanner 131 passes through the dichroic mirror 174, and enters the eye E again through a common optical path with the OCT measurement light 104. Here, the common optical path of the SLO measurement light 106 and the OCT measurement light 104 includes an optical path passing through the dichroic mirror 174, mirrors 117 to 122, the Y scanner 133, the mirror 123, and the dichroic mirrors 175 and 176.
The common optical path of the SLO measurement light 106 and the OCT measurement light 104 will be summarized. The common optical path includes an optical path passing through dichroic mirror 177 to dichroic mirror 173 and an optical path passing through dichroic mirror 174 to dichroic mirror 176.

  When the SLO measurement light 106 enters the eye E, it is reflected or scattered by the retina Er, returns as the SLO return light 107 along the optical path of the SLO measurement light 106, is reflected by the dichroic mirror 177, and transmits through the beam splitter 172. . The SLO return light 107 transmitted through the beam splitter 172 is condensed by the lens 156 and passes through the pinhole plate 178. The pinhole position of the pinhole plate 178 is adjusted to a position conjugate with the fundus, and the pinhole plate 178 functions as a confocal stop that blocks unnecessary light from other than the conjugate point.

  The SLO return light 107 that has passed through the pinhole plate 178 is received by the light receiving element 192. As the light receiving element 192, for example, an APD (Avalanche Photo Diode) is used. However, any other light receiving element may be used as the light receiving element 192 according to a desired configuration. The light receiving element 192 converts the received light into a voltage signal according to the light intensity. The obtained voltage signal group is converted into a digital value. The control unit 190 can perform data processing on the output signal of the light receiving element 192 converted into the digital value, and generate a fundus oculi planar image. Known data processing for generating a fundus plane image from an output signal from the light receiving element 192 can be used for data processing when generating a fundus plane image. The control unit 190 displays the generated fundus plane image on a display unit (not shown).

Next, the fixation light optical system will be described.
The fixation light optical system includes a dichroic mirror 175 and a fixation light panel 194.
The dichroic mirror 175 reflects visible light of the fixation light panel 194 and transmits light from the light sources 101 and 102 according to the wavelength of the light. Therefore, the pattern displayed on the fixation light panel 194 is projected on the retina Er of the eye E through the dichroic mirror 175. By displaying a desired pattern on the fixation light panel 194, the fixation direction of the eye E can be designated, and the range of the retina Er to be imaged can be set. As the fixation light panel 194, for example, an organic EL panel is used. However, the fixation light panel 194 may be another display. The fixation light panel 194 is connected to the control unit 190 and is controlled by the control unit 190.

Next, the anterior eye observation optical system will be described.
The anterior eye observation optical system includes a dichroic mirror 176, an anterior eye observation camera 193, and an unillustrated anterior eye illumination light source.
The dichroic mirror 176 reflects the infrared light of the anterior eye illumination light source and transmits the visible light of the fixation light panel 194 and the light from the light sources 101 and 102 according to the wavelength of the light. The optical axis of the anterior eye observation camera 193 is adjusted to coincide with the optical axes of the OCT optical system and the SLO optical system. Therefore, by observing the image of the anterior segment of the eye E based on the output from the anterior eye observation camera 193 on the display unit and adjusting the image to the reference position, the X direction of the OCT optical system and the SLO optical system with respect to the eye E is examined. And alignment in the Y direction. The anterior eye observation camera 193 is connected to the control unit 190 and is controlled by the control unit 190.

The focus of the anterior eye observation camera 193 is adjusted so that the iris of the eye E is focused when the working distance (working distance in the Z direction) of the OCT optical system and the SLO optical system is matched. Therefore, by observing the iris in the image of the anterior segment on the display unit and focusing, it is possible to perform the Z-direction alignment of the OCT optical system and the SLO optical system.
In this embodiment, the anterior eye illumination light source uses an LED having a wavelength of 970 nm, and the anterior eye observation camera 193 uses a CCD camera. However, the anterior eye illumination light source and the anterior eye observation camera are not limited to this case, and may be another light source, an image sensor, or the like. Further, the wavelength of the anterior eye illumination light source may be changed according to a desired configuration.

(Relation of shooting range)
Next, with reference to FIG. 2, the relationship between the imaging ranges of the OCT optical system and the SLO optical system will be described with reference to FIG.
In FIG. 2, the solid line indicates the imaging range 220 of the OCT optical system, and the area inside the broken line indicates the imaging range 210 of the SLO optical system. 4 schematically shows the relationship between the imaging range 220 of the OCT optical system and the imaging range 210 of the SLO optical system when one line is imaged by the OCT optical system.
In the OCT optical system and the SLO optical system, since the Y scanner 133 is disposed on the common optical path, scanning is performed simultaneously in the Y direction (up and down direction in FIG. 2). On the other hand, in the X direction (horizontal direction on the paper surface of FIG. 2), the scanning ranges in the X direction of the OCT optical system and the SLO optical system are independent of each other in order to perform scanning using separate X scanners 132 and 131. Can be set to For example, in FIG. 2, the imaging range 220 of the OCT optical system is set substantially at the center of the imaging range 210 of the SLO optical system, but the relationship of the imaging range in the X direction is not limited to this case. The imaging range 220 of the OCT optical system may be arbitrarily set regardless of the imaging range 210 of the SLO optical system.

  Further, since the scanning speed of the resonance mirror of the X scanner 131 is faster than that of the galvanometer mirror of the X scanner 132, the SLO measurement light 106 is scanned a plurality of times in the X direction during one scanning in the Y direction. Therefore, for example, the imaging range (one line) of the OCT optical system having the length L can be captured by sampling (A scan) at m points, and the L × L SLO imaging range can be captured by m X scans. . Thus, an L × L fundus plane image (two-dimensional image) can be acquired by the SLO optical system while capturing a one-line tomographic image having a length L by the OCT optical system. The numerical values of L and m can be set arbitrarily according to a desired configuration.

  When capturing a 3D volume image, in addition to scanning by the Y scanner 133, the X scanner 132 scans the OCT measurement light 104, and changes the scanning position of the X scanner 132 to capture one line in the Y direction described above. And repeat. For example, an L × L 3D volume image can be obtained by shooting m lines in the range of L in the X direction. During this time, m L × L fundus plane images can be acquired using the SLO optical system.

(Tracking procedure)
Next, a method of correcting a position shift (tracking) based on a fundus plane image acquired using the SLO optical system will be described.
In the tracking processing according to the present embodiment, the control unit 190 uses the SLO optical system to perform the first imaging when the line tomographic image at the same position is imaged a plurality of times using the OCT optical system. A fundus plane image based on fundus information (first fundus information) is used as a reference image. Next, the control unit 190 converts a fundus image based on fundus information (second fundus information) acquired using the SLO optical system at the time of second and subsequent imaging using the OCT optical system into a target image for position shift detection. And The control unit 190 calculates the amount of displacement of the target image with respect to the reference image. The calculation of the amount of displacement can be performed by image processing such as pattern matching.

  The control unit 190 controls the X scanner 132 and the Y scanner 133 so as to correct the calculated displacement. Accordingly, the control unit 190 can perform fundus tracking for correcting a shift in the imaging position of the tomographic image based on the movement of the fundus due to the fixation fine movement or the like. The acquired plurality of line tomographic images at the same position can be used for noise reduction processing of a tomographic image by superposition.

  This fundus tracking can be similarly applied to the case of acquiring a 3D volume image using the OCT optical system. In this case, as described above, the tomographic image of one line in the Y direction is repeatedly acquired while changing the position in the X direction using the OCT optical system. At this time, the control unit 190 sets a fundus plane image based on fundus information of the eye E acquired at the time of the first (first line) imaging as a reference image. Further, the control unit 190 sets a fundus oculi planar image based on fundus oculi information acquired at the time of the second (second-line) or later imaging as a target image. The control unit 190 calculates the amount of displacement between the reference image and the target image, and performs fundus tracking. Accordingly, even when acquiring a 3D volume image, it is possible to correct the deviation of the imaging position of the tomographic image with respect to the retina Er of the eye E.

  In addition, at the time of the first imaging using the OCT optical system, the entire fundus planar image acquired using the SLO optical system may be used as the reference image, or a partial image of the fundus planar image may be used. Similarly, for the target image, the entire fundus plane image acquired using the SLO optical system may be used, or a partial image of the fundus plane image may be used. When a partial image of the fundus oculi planar image is used as the target image, the acquisition interval of the target image can be reduced, and the control rate of fundus tracking can be increased. Therefore, it becomes easy to correct the displacement due to the fast movement of the fundus.

  Note that the image size of the reference image may be set larger than the image size of the target image. In this case, while maintaining the control rate by keeping the image size of the target image small, it is easy to secure a large overlapping area between the reference image and the target image even if the positional deviation amount between the reference image and the target image is large. It becomes easier to correct the displacement. If the movement of the fundus is slow and the control rate of fundus tracking has a margin, the image size of the target image may be set to be larger than the image size of the reference image. Even in this case, it is easy to correct a positional shift due to a large movement of the fundus. In other words, by setting one image size of the reference image and the target image to be larger than the other image size, it becomes easy to correct a positional shift due to a large movement of the fundus.

(Procedure for photographing the fundus)
Next, a procedure of photographing the fundus of the fundus imaging apparatus 100 will be described with reference to FIG. FIG. 3 is a flowchart showing an example of a procedure for photographing the fundus. The processing of the flowchart in FIG. 3 is realized by the control unit 190 executing a program stored in the memory.
In S301, the control unit 190 turns on an unillustrated anterior eye illumination light source in response to the examiner pressing an anterior eye illumination light source button displayed on the display unit. When the anterior eye illumination light source is turned on, the control unit 190 generates an image of the anterior eye part of the eye E based on the output of the anterior eye observation camera 193 and displays the image on the display unit.

In S302, the control unit 190 moves the imaging unit provided with the OCT optical system and the SLO optical system with respect to the eye E in the X, Y, and Z directions based on the image of the anterior segment displayed on the display unit. (XYZ alignment of the anterior eye) is performed.
Specifically, the examiner observes the image of the anterior segment and inputs an alignment instruction. The control unit 190 controls a driving mechanism (not shown) of the imaging unit according to the input of the examiner, and performs alignment of the imaging unit with respect to the eye E to be inspected. As described above, the position of the anterior eye observation camera 193 in the X, Y, and Z directions with respect to the OCT optical system and the SLO optical system is adjusted. Therefore, the examiner adjusts the positions of the imaging unit in the X, Y, and Z directions so that the XY position and the focus (Z position) of the image of the anterior segment displayed on the display unit are aligned, whereby the OCT optical system is adjusted. And the SLO optical system can be aligned in the X, Y, and Z directions. The positioning of the imaging unit may be performed by the examiner operating a driving mechanism of the imaging unit (not shown).

In S303, the control unit 190 turns off the anterior eye illumination light source in response to the examiner pressing the anterior eye illumination light source button displayed on the display unit again.
In S304, the control unit 190 turns on the light source 101 of the OCT optical system and the light source 102 of the SLO optical system in response to the examiner pressing a light source button (not shown) displayed on the display unit. However, the timing of turning on the light source 101 of the OCT optical system is not limited to this case. For example, the light source 101 may be turned on after the rough focus adjustment in S305 described later. After turning on the light source 102 of the SLO optical system, the control unit 190 generates a fundus oculi planar image based on the output of the light receiving element 192 and displays the image on the display unit.

In S305, the control unit 190 adjusts the approximate focus (rough focus adjustment) of the SLO optical system and the OCT optical system according to the input of the examiner based on the fundus plane image displayed on the display unit.
Specifically, the examiner observes the fundus plane image and performs an operation of moving a focus adjustment bar (not shown) displayed on the display unit. The control unit 190 moves the electric stage 126 according to the operation of the examiner. The electric stage 126 and the mirrors 119 and 120 are arranged on a common optical path of the OCT measurement light 104 and the SLO measurement light 106. Therefore, by performing the focus adjustment of the SLO measurement light 106, the rough focus adjustment of the OCT measurement light 104 is also performed at the same time. Here, focus adjustment is performed so that the luminance of the fundus oculi planar image is maximized. At this time, the control unit 190 arranges the electric stage 127 of the SLO optical system at a position in a preset initial state. Here, as the initial position of the electric stage 127, the position of the electric stage 127 is set such that the focus positions of the OCT measurement light 104 and the SLO measurement light 106 substantially match.

In S306, the control unit 190 performs XY fine alignment of the imaging unit with respect to the eye E in accordance with the input of the examiner based on the position of the Hartmann image of the wavefront sensor 181 displayed on the display unit. In the XY fine alignment, the examiner observes the position of the Hartmann image of the wavefront sensor 181 displayed on the display unit, and the control unit 190 moves the X direction and the Y direction of the imaging unit with respect to the subject's eye E in response to the input of the examiner. Perform precise positioning in the directions.
Here, the wavefront sensor 181 is adjusted such that the center position of the wavefront sensor 181 matches the optical axes of the OCT optical system and the SLO optical system. Therefore, the examiner adjusts the position of the imaging unit with respect to the eye E so that the Hartmann image is aligned with the center of the wavefront sensor 181, thereby aligning the OCT optical system and the SLO optical system in the X and Y directions. It can be performed. Note that the display unit may display an index or the like and a Hartmann image corresponding to the center position of the wavefront sensor 181.

In S307, the control unit 190 starts the wavefront correction by the deformable mirror 182 in response to the examiner pressing the wavefront correction button displayed on the display unit. Here, the control unit 190 deforms the shape of the deformable mirror 182 based on the aberration measured by the wavefront sensor 181, and corrects the aberration of the eye E other than the defocus component. Note that the aberration correction using the deformable mirror 182 can use a known method.
The deformable mirror 182 is arranged on a common optical path of the OCT measurement light 104 and the SLO measurement light 106. Thus, by correcting the aberration of the eye E by deforming the deformable mirror 182 with respect to the OCT measurement light 104, the aberration of the eye E can be corrected with respect to the SLO measurement light 106.

  In S308, the control unit 190 adjusts the optical path length of the reference light 103 after starting the wavefront correction. Specifically, the examiner performs an operation of moving a reference optical path length adjustment bar (not shown) displayed on the display unit. The control unit 190 controls the electric stage 125 according to the operation of the examiner to adjust the optical path length of the reference light 103. Here, the control unit 190 displays the tomographic image acquired using the OCT optical system on the display unit, and according to the input by the examiner, the image of the desired layer in the tomographic image is displayed in the tomographic image display area. The optical path length of the reference light 103 is adjusted so as to match a desired position.

  In step S309, the control unit 190 performs fine focus adjustment of the OCT optical system. Specifically, the examiner performs an operation of moving a focus adjustment bar (not shown) displayed on the display unit based on the tomographic image. The control unit 190 controls the electric stage 126 according to the operation of the examiner to perform fine focus adjustment of the OCT optical system. In an OCT optical system having a high lateral resolution, since the numerical aperture (NA) of the measurement light at the fundus is large and the depth of focus is shallow, it is difficult to simultaneously focus over the entire area in the depth direction of the retina Er. Therefore, in S309, fine focus adjustment is performed so that the OCT measurement light 104 is focused on a layer of the retina Er to be photographed. For example, when it is desired to image a blood vessel on the surface of the retina, the control unit 190 controls the electric stage 126 to adjust the focus of the OCT measurement light 104 so that the luminance of that part is maximized. After the OCT measurement light 104 is adjusted to a desired focus state by fine focus adjustment, the process proceeds to S310.

  In S310, the control unit 190 performs the SLO fine focus adjustment based on the fundus plane image acquired using the SLO optical system. Specifically, the examiner performs an operation of moving an SLO focus adjustment bar (not shown) displayed on the display unit. The control unit 190 controls the electric stage 127 according to the operation of the examiner. Here, focus adjustment is performed so that the contrast of the visual cells in the fundus oculi planar image displayed on the display unit is increased. The position at which the SLO optical system focuses is not limited to the photoreceptor cells. The position where the SLO optical system is focused may be a position having another characteristic point such as a blood vessel, if desired tracking accuracy can be achieved.

The focus lens 157 mounted on the motorized stage 127 is arranged on a dedicated optical path of the SLO optical system branched from a common optical path with the OCT optical system. Therefore, by changing the position of the focus lens 157 with the electric stage 127, the focus of the SLO optical system can be adjusted without affecting the focus state of the OCT optical system.
The focus lens 157 is disposed on a common optical path that shares at least a part of the optical path of the SLO measurement light 106 and the optical path of the SLO return light 107. Therefore, the focal position of the SLO measurement light 106 can be adjusted to a desired position of the retina Er, and at the same time, the focal position of the SLO return light 107 from that position can be adjusted to the pinhole position of the pinhole plate 178.
Note that the focus adjustment of the SLO optical system may be performed by moving the lens 155 disposed on the dedicated optical path of the SLO measurement light 106 and the lens 156 disposed on the dedicated optical path of the SLO return light 107 in the optical axis direction. it can. However, in this case, it is necessary to control the positions of the lens 155 and the lens 156, respectively, which complicates the device configuration and control. On the other hand, when the focus adjustment of the SLO optical system is performed using the focus lens 157, the device configuration and control can be simplified.

  In S311, the control unit 190 starts fundus tracking in response to the examiner pressing a tracking button (not shown) displayed on the display unit. As described above, the control unit 190 calculates the amount of positional deviation from the feature points of the fundus plane image acquired using the SLO optical system, and controls the X scanner 132 and the Y scanner 133 based on the calculated amount of deviation. To perform fundus tracking. Therefore, the control unit 190 functions as an eye movement detecting unit. By tracking the fundus, it is possible to acquire a plurality of tomographic images, a moving image, a 3D volume image, and the like used for noise processing by superimposing tomographic images with a small displacement.

  In S312, the control unit 190 starts tracking, and acquires a fundus tomographic image and a fundus plane image in response to the examiner pressing a shooting button (not shown) displayed on the display unit. Interference light (light 108) between the OCT measurement light 104 and the reference light 103 is received by the line camera 191 and converted into a voltage signal. Further, the obtained voltage signal group is converted into a digital value, and the control unit 190 stores and processes the data. The control unit 190 generates a fundus tomographic image by processing data based on the interference light. The SLO return light 107 is received by the light receiving element 192 and is converted into a voltage signal. Further, the obtained voltage signal group is converted into a digital value, and the control unit 190 stores and processes the data. The control unit 190 generates a fundus plane image by processing data based on the SLO return light 107.

  In the present embodiment, while performing accurate fundus tracking using the fundus plane image acquired by the SLO optical system, the OCT optical system is used to focus on a desired layer of the retina Er, thereby achieving high-resolution SN. A fundus tomographic image with a good ratio can be taken. In addition, since the aberration fluctuation due to the movement of the focus lens 157 in the SLO optical system does not affect the OCT optical system, it is possible to acquire a fundus tomographic image using the OCT optical system while accurately maintaining the aberration correction.

  As described above, the fundus imaging apparatus 100 of the present embodiment converts the fundus information of the eye E using the OCT optical system that acquires the tomographic information of the eye E using the OCT measurement light 104 and the SLO measurement light 106. And an SLO optical system to be acquired. Further, the fundus imaging apparatus 100 includes a common optical path that shares at least a part of the optical path of the OCT measurement light 104 and the optical path of the SLO measurement light 106, and the chromatic aberration correction lens 10 that corrects chromatic aberration in the subject's eye branches from the common optical path. The optical path of the OCT measurement light 104 is provided. Specifically, the chromatic aberration correction lens 10 is provided on the light source 101 side that emits the OCT measurement light 104 in the optical path of the OCT measurement light 104 branched from the common optical path. Here, since the OCT measurement light 104 has a wavelength at which the influence of the chromatic aberration of the eye E is more likely to be greater than the SLO measurement light 106, the chromatic aberration of the eye to be inspected is reduced by the chromatic aberration correction lens 10 provided in the optical path of the OCT measurement light 104. Can be corrected. Therefore, a high-resolution and high-quality fundus tomographic image can be obtained. On the other hand, since the chromatic aberration correcting lens 10 is not provided in the common optical path and the optical path of the SLO measurement light 106, it is possible to prevent the optical performance of the SLO optical system from being affected.

  Further, the fundus imaging apparatus 100 has a dichroic mirror 177 as light guiding means for guiding the OCT measuring light 104 and the SLO measuring light 106 to a common optical path, respectively. The chromatic aberration correction lens 10 includes a light source 101 of the OCT optical system and a dichroic mirror 177. And provided between them. Therefore, the chromatic aberration correction lens 10 can be provided in the optical path of the OCT measurement light 104 with a relatively simple configuration as compared with a configuration in which the chromatic aberration correction lens 10 is branched in the middle of the common optical path.

Further, the fundus imaging apparatus 100 includes a Badal optical system including mirrors 119 and 120 provided on a common optical path, and includes a focus lens 157 on an optical path of the SLO measurement light 106 branched from the common optical path. Here, the focus adjustment range by the focus lens 157 is narrower than the focus adjustment range by the Badal optical system.
Further, the fundus imaging apparatus 100 includes a wavefront sensor 181 that measures the aberration of the return light of the OCT measurement light 104, and a deformable mirror 182 provided on a common optical path. The control unit 190 controls a change in the shape of the deformable mirror 182 based on the aberration measured by the wavefront sensor 181.
Further, the fundus imaging apparatus 100 includes an X scanner 132 and a Y scanner 133 that scan the OCT measurement light 104 two-dimensionally on the fundus. The control unit 190 detects the movement of the fundus based on the fundus information of the eye E acquired using the SLO optical system, and controls the X scanner 132 and the Y scanner 133 based on the detected movement of the fundus.
With such a configuration, the fundus imaging apparatus 100 can adjust the focal positions of the OCT optical system and the SLO optical system to different positions while having a compact configuration. Therefore, in the fundus imaging apparatus 100, the focal position of the OCT optical system can be adjusted to the layer to be photographed, and the focal position of the SLO optical system can be adjusted to a layer having many feature points advantageous for position detection for fundus tracking. it can. Therefore, it is possible to photograph a tomographic image with high lateral resolution using the OCT optical system while performing highly accurate fundus tracking using the SLO optical system. Therefore, it is possible to acquire a plurality of tomographic images, moving images, and 3D volume images while suppressing the displacement during imaging to be smaller.

Further, the fundus imaging apparatus 100 includes a Y scanner 133 that scans the OCT measurement light 104 and the SLO measurement light 106 in the Y direction (first direction), and an X direction (second direction) perpendicular to the Y direction. Direction). Further, the fundus imaging apparatus 100 includes an X scanner 131 that scans the SLO measurement light 106 in the X direction. Here, the control unit 190 causes the Y scanner 133 to repeatedly scan the OCT measurement light 104 and the SLO measurement light 106 while performing one scan by the X scanner 132. The control unit 190 causes the X scanner 131 to repeatedly scan the SLO measurement light 106 while performing one scan by the Y scanner 133.
The common optical path between the OCT optical system and the SLO optical system includes a dichroic mirror 173 that separates the OCT measurement light 104 and the SLO measurement light 106. Further, the common optical path includes a dichroic mirror 174 that combines the OCT measurement light 104 and the SLO measurement light 106 separated by the dichroic mirror 173. Here, the X scanner 132 is arranged on the optical path of the OCT measurement light 104 separated by the dichroic mirror 173, and the X scanner 131 is arranged on the optical path of the SLO measurement light 106 similarly separated.
With such a configuration, the fundus imaging apparatus 100 shares the Y scanner 133 in the OCT optical system and the SLO optical system, so that the fundus imaging apparatus 100 can have a more compact configuration as compared to a case where a separate Y scanner is provided for each optical system. it can. Further, since the fundus imaging apparatus 100 uses separate X scanners for the X scanner 132 and the X scanner 131, the X-direction imaging ranges of the OCT optical system and the SLO optical system can be set independently of each other. Further, the fundus imaging apparatus 100 can rotate the X scanners 131 and 132 in the SLO optical system and the OCT optical system at different periods, and change the scanning speed of the measuring light of the SLO optical system to the scanning speed of the measuring light in the OCT optical system. Can be faster.

<Second embodiment>
Next, a fundus imaging device 400 according to a second embodiment of the present invention will be described.
(Device configuration)
FIG. 4 is a diagram illustrating an example of the configuration of the fundus imaging device 400. Here, a description will be given focusing on differences from the fundus imaging apparatus 100 of the first embodiment, and a description of the same configuration as the fundus imaging apparatus 100 of the first embodiment will be omitted using the same reference numerals. .
The basic configuration of the fundus imaging device 400 is the same as that of the fundus imaging device 100 according to the first embodiment. However, the fundus imaging apparatus 400 differs from the fundus imaging apparatus 100 in that the second focusing unit is not disposed on the dedicated optical path of the SLO optical system, and the second focusing unit is disposed on the dedicated optical path of the OCT optical system. In the fundus imaging apparatus 400, a focus lens 457 is disposed as a second focus unit in a dedicated optical path of the OCT optical system branched from a common optical path of the OCT optical system and the SLO optical system.

  In the present embodiment, a focus lens 457 and a lens 458 are provided between the chromatic aberration correction lens 10 and the dichroic mirror 177 in the optical path of the OCT measurement light 104. Here, by providing the focus lens 457 after the chromatic aberration correction lens 10, it is possible to correct the chromatic aberration of the subject's eye without being affected by the change in the light flux due to the focus state. The focus lens 457 is mounted on the electric stage 427. The electric stage 427 is movable in the optical axis direction of the OCT measurement light 104 as shown by the arrow. The electric stage 427 is controlled by the control unit 190.

  Although the focus lens 457 is a convex lens and the lens 458 is a concave lens in FIG. 4, the configurations of the focus lens 457 and the lens 458 are not limited to this case. For example, the focus lens 457 may be a concave lens, the lens 458 may be a convex lens, or both may be convex lenses, and an intermediate image may be formed therebetween.

(Procedure for photographing the fundus)
Next, a procedure for photographing the fundus of the fundus imaging apparatus 400 will be described with reference to FIG. FIG. 5 is a flowchart illustrating an example of a procedure for photographing the fundus. The processing of the flowchart in FIG. 5 is realized by the control unit 190 executing a program stored in the memory. Note that steps S501 to S507 are the same as steps S301 to S307 in the imaging procedure according to the first embodiment, and a description thereof will not be repeated.
When the imaging is started and the alignment, the rough focus adjustment, and the wavefront correction are started in S501 to S507 as in S301 to S307 in the first embodiment, the process proceeds to S508.

In step S508, the control unit 190 performs fine focus adjustment of the SLO optical system. Specifically, the examiner performs an operation of moving a focus adjustment bar (not shown) displayed on the display unit based on the fundus plane image. The control unit 190 controls the electric stage 126 according to the operation of the examiner to perform fine focus adjustment of the SLO optical system. Here, focus adjustment is performed so that the contrast of the visual cells in the fundus oculi planar image displayed on the display unit is increased. The position at which the SLO optical system focuses is not limited to the photoreceptor cells. The position where the SLO optical system is focused may be a position having another characteristic point such as a blood vessel, if desired tracking accuracy can be achieved.
At this time, the control unit 190 places the electric stage 427 of the OCT optical system at a position in a preset initial state. Here, as the position of the electric stage 427 in the initial state, the position of the electric stage 427 is set such that the focus positions of the OCT measurement light 104 and the SLO measurement light 106 substantially match.

In step S509, the control unit 190 starts fundus tracking as in step S311 of the first embodiment.
In S510, the control unit 190 adjusts the reference optical path length as in S308 of the first embodiment.
In step S511, the control unit 190 performs the OCT fine focus adjustment. Specifically, the examiner performs an operation of moving an OCT focus adjustment bar (not shown) displayed on the display unit based on the tomographic image. The control unit 190 controls the electric stage 427 according to the operation of the examiner to move the focus lens 457, and performs fine focus adjustment of the OCT optical system. Here, focus adjustment is performed so that the luminance of the layer to be photographed in the tomographic image displayed on the display unit is maximized.

  In the present embodiment, the focus lens 457 is disposed on a dedicated optical path of the OCT optical system branched from a common optical path with the SLO optical system. Therefore, by changing the position of the focus lens 457 with the electric stage 427, the focus of the OCT optical system can be adjusted without affecting the focus state of the SLO optical system.

In step S512, the control unit 190 performs shooting in the same procedure as in step S312 of the first embodiment.
As described above, in the fundus imaging apparatus 400 of the present embodiment, the focus lens 457 as the second focus unit is provided on the optical path of the OCT measurement light 104 branched from the common optical path. That is, the focal positions of the OCT optical system and the SLO optical system can be adjusted to different positions while having a compact device configuration. Therefore, like the fundus imaging apparatus 100 of the first embodiment, the fundus imaging apparatus 400 according to the present embodiment focuses on a desired layer using the OCT optical system to achieve high resolution while performing accurate fundus tracking. I can shoot. Further, since the fundus imaging apparatus 400 can change the focus of the OCT optical system to a different layer while performing fundus tracking using the SLO optical system, for example, a tomographic image can be obtained at a plurality of focus positions of the OCT optical system. The operation becomes easy when photographing is performed.

<Modification 1>
In the first and second embodiments, the mirrors 119 and 120 mounted on the motorized stage 126 disposed in the common optical path of the OCT optical system and the SLO optical system are used as first focusing means, and are moved by moving these mirrors. Focus adjustment and fine focus adjustment were performed. However, the first focus unit used for these focus adjustments is not limited to the above-described configuration. For example, a deformable mirror 182 disposed on a common optical path of the OCT optical system and the SLO optical system can be used as the first focus unit.
In particular, the fine focus adjustment may be performed by deforming the deformable mirror 182. In this case, the control unit 190 controls the target shape of the deformable mirror 182 based on the measurement value of the wavefront sensor 181 by giving an offset of the defocus component to the target shape. Thus, the focus positions of the OCT optical system and the SLO optical system can be changed while correcting the aberration of the eye E. In the rough focus adjustment, if the amount of focus adjustment is small, the deformable mirror 182 can be used similarly.
Further, as the first focus means, any other focus means such as a focus lens, an electro-optical element, a piezo element, a liquid crystal optical element, and a deformable mirror may be used.

<Modification 2>
Further, in the first and second embodiments, the focus adjustment is performed by independently controlling the first focus unit and the second focus unit. However, the fundus imaging apparatus uses the first focus unit and the second focus unit. A mode in which the focus unit is controlled in association with the focus unit may be provided.
The apparatus configuration in this case is the same as that of the fundus imaging apparatus 100 shown in FIG. However, the difference lies in that the first focus means and the second focus means are controlled in conjunction with each other during the OCT fine focus adjustment (S511).

  In this case, in S508, the control unit 190 controls the electric stage 126 and moves the focus lens 157 to perform fine focus adjustment of the SLO optical system. Thereafter, in step S511, when the electric stage 126 is moved to perform the OCT fine focus adjustment, the electric stage 127 arranged on the dedicated optical path of the SLO optical system is controlled so as to operate in a direction to cancel the adjustment by the electric stage 126. I do. In other words, when the OCT fine focus is adjusted by the first focus unit arranged on the common optical path, the control unit 190 controls the second focus unit arranged on the dedicated optical path to cancel the influence of the adjustment. Operate in conjunction with the focus means. Thus, the focus of the OCT optical system can be adjusted without changing the focus state of the SLO optical system.

After that, when the luminance of the desired layer is maximized by the OCT fine focus adjustment, the control unit 190 performs imaging in the same manner as in S312 in the first embodiment.
Even in this case, while performing accurate fundus tracking, a desired layer can be focused by the OCT optical system and an image with a high S / N ratio can be captured with high resolution. In addition, since the focus of the OCT optical system can be changed to a different layer while the fundus tracking is performed using the SLO optical system, the operation is facilitated, for example, when imaging is performed at a plurality of focus positions. In addition, since the aberration fluctuation due to the movement of the focus lens 157 mounted on the electric stage 127 does not affect the OCT optical system, a fundus tomographic image can be obtained using the OCT optical system while performing aberration correction with high accuracy. Further, in the configuration of the fundus imaging device 400, the same processing can be performed when performing the fundus imaging procedure described in the flowchart of FIG.

Note that the focus adjustment may be performed by deforming the deformable mirror 182 as the first focus unit. In this case, the control unit 190 may control the target shape of the deformable mirror 182 by giving an offset of the defocus component, and control the electric stage 127 as the second focusing means so as to cancel the offset amount.
Further, an interlocking mechanism for interlocking the first focus unit and the second focus unit may be provided. In this case, by controlling the interlocking mechanism, the control unit 190 can interlock the first focusing unit and the second focusing unit. In addition, the interlocking mechanism may be configured so that the interlock between the first focusing unit and the second focusing unit can be released. In this case, the control unit 190 cancels the interlocking by the interlocking mechanism and connects with the first focusing unit. The second focus means can be controlled separately.

<Modification 3>
When rough focus adjustment is performed in S305 of the first embodiment and S505 of the second embodiment, the adjustment of the optical path length by the optical path length adjustment unit provided in the reference optical path and the focus adjustment by the first focus unit are performed. Control may be performed in conjunction with each other.
In this case, the control unit 190 controls the electric stage 125 to move the mirror 124 so that the optical path length changes by substantially the same amount as the amount of change in the optical path length due to the movement of the mirrors 119 and 120 during the rough focus adjustment. Thereby, the focus can be adjusted without changing the optical path length difference between the OCT measurement light 104 and the reference light 103. Therefore, the amount of movement of the mirror 124 when performing the reference optical path length adjustment in S308 of the first embodiment and S510 of the second embodiment can be reduced. If the movement amount of the mirror 124 mounted on the motorized stage 125 is small, the adjustment time of the optical path length can be shortened, and the total imaging time from the start of the operation to the completion of the imaging can be shortened. The burden can be reduced.

Further, an interlocking mechanism for interlocking the optical path length adjusting means and the first focusing means may be provided. In this case, by controlling the interlocking mechanism, the control unit 190 can interlock the mirror 124 mounted on the electric stage 125 with the first focusing unit. In addition, the interlocking mechanism may be configured so that the interlock between the optical path length adjusting unit and the first focusing unit can be released. In this case, the control unit 190 cancels the interlocking by the interlocking mechanism and connects the optical path length adjusting unit with the first focusing unit. One focus means can be controlled separately.
In the first and second embodiments, the case where the optical path length adjusting means is constituted by the mirror 124 provided on the optical path of the reference light 103 has been described. However, the present invention is not limited to this case. It may be provided on the optical path of the measurement light 104.

<Modification 4>
In the first and second embodiments, the case where the second focus unit is provided on one of the dedicated optical path of the OCT optical system and the dedicated optical path of the SLO optical system has been described. However, the second focus unit may be provided on both the dedicated optical path of the OCT optical system and the dedicated optical path of the SLO optical system. As described above, the second focus unit is used for fine focus adjustment of each optical system because the focus adjustment range is narrower than the first focus unit and the diopter range of the eye E to be handled is narrow. . Therefore, in this modification, in the imaging procedure, fine focus after rough focus is separately performed by the respective second focus units provided on the dedicated optical path of the OCT optical system and the dedicated optical path of the SLO optical system.
Even in such a case, since the second focus unit has a narrower focus adjustment range than the first focus unit, for example, the moving range of the motorized stage equipped with the focus lens can be narrowed, and compared with the conventional device. The device configuration can be made compact. Further, the second focus means is not limited to the electric stage equipped with the focus lens. For example, the second focus unit may be configured by an electro-optical element such as a crystal of potassium tantalate niobate, or another piezo element, a liquid crystal optical element, or a deformable mirror capable of obtaining the same effect. . In this case, it is not necessary to secure the moving range of the electric stage, so that the device configuration can be made more compact.

<Other modifications>
In the above-described embodiment and modified examples, the case has been described in which the control unit 190 performs various alignments, optical path length adjustment, and focus adjustment according to the input of the examiner. However, based on the various alignments described above, the optical path length adjustment, the anterior ocular segment image used in the focus adjustment, the fundus plane image, the Hartmann image, the tomographic image, and the like, the control unit 190 automatically adjusts these alignments and adjustments. May be performed. In this case, for example, the control unit 190 can perform these alignments and adjustments based on the luminance of the fundus oculi planar image, the layer to be photographed, and the like, similarly to the above-described alignment and adjustments.

  Further, in the above-described embodiment and the modified example, the configuration of the Michelson interferometer is used as the interference optical system of the fundus imaging apparatus, but the configuration of the interference optical system is not limited to this case. For example, the interference optical system of the fundus imaging device may have a configuration of a Mach-Zehnder interferometer. In addition, in the above-described embodiments and modified examples, the wavelength of light reflected or transmitted by each dichroic mirror is arbitrary, and a configuration may be adopted in which light opposite to the above-described configuration is reflected or transmitted. .

  Further, in the above-described embodiment and the modified example, the Y scanner 133 is shared between the OCT optical system and the SLO optical system. However, a separate Y scanner may be provided for the OCT optical system and the SLO optical system. Further, the first focusing means arranged on the common optical path is not limited to the structure arranged between the Y scanner 133 and the X scanners 131 and 132. For example, at least one of the X scanners 131 and 132 may be provided between the subject's eye E and the first focusing unit. Further, the Y scanner 133 does not have to be provided between the eye E and the first focusing unit.

  Further, in the above-described embodiment and the modified example, the OCT optical system is configured as a spectral domain OCT (SD-OCT) optical system using an SLD as a light source, but is not limited to this case. Any other type of OCT optical system, such as a wavelength-swept OCT (SS-OCT) optical system using a wavelength-swept light source capable of sweeping the wavelength of emitted light, can be applied.

<Other embodiments>
The present invention supplies a program for realizing one or more functions of the above-described embodiments to a system or an apparatus via a network or a storage medium, and one or more processors in a computer of the system or the apparatus read and execute the program. This processing can be realized. Further, it can be realized by a circuit (for example, an ASIC) that realizes one or more functions.
Although the present invention has been described with reference to the exemplary embodiments, the present invention is not limited to the above-described exemplary embodiments. The present invention includes inventions modified within a scope not contrary to the gist of the present invention and inventions equivalent to the present invention. In addition, the above-described embodiments and modifications can be appropriately combined without departing from the spirit of the present invention. In addition, not all combinations of the features described in each embodiment and modification are not necessarily essential to the solution of the present invention.

10: chromatic aberration correction lens, 100: fundus imaging device, 101, 102: light source, 119, 120: mirror, 126, 127: electric stage, 141: optical coupler, 154: lens 157: focus lens, 173, 174, 177: Dichroic mirror, 191: line camera, 192: light receiving element, 400: fundus imaging device, 426: electric stage, 457: focus lens, E: eye to be examined

Claims (18)

An OCT optical system that acquires tomographic information of the subject's eye using the OCT measurement light,
An SLO optical system that acquires fundus information of the eye using the SLO measurement light,
A common optical path that shares at least a part of the optical path of the OCT measurement light and the optical path of the SLO measurement light;
A chromatic aberration corrector provided in an optical path of the OCT measurement light branched from the common optical path, for correcting chromatic aberration in the eye to be inspected;
A fundus imaging device comprising: Light guide means for guiding the OCT measurement light and the SLO measurement light to the common optical path,
The chromatic aberration correction unit includes:
The fundus imaging apparatus according to claim 1, wherein the fundus imaging apparatus is provided between a light source that emits the OCT measurement light and the light guiding unit. The light guide means,
3. The fundus imaging apparatus according to claim 2, wherein the first optical unit transmits one of the OCT measurement light and the SLO measurement light and reflects the other measurement light. 4. Splitting means for splitting the light emitted from the light source into the OCT measurement light and the reference light,
Second optical means for converting the OCT measurement light split by the splitting means into parallel light,
The chromatic aberration correction unit includes:
The fundus imaging apparatus according to claim 2, wherein the fundus imaging apparatus is provided between the second optical unit and the light guide unit. First focus means provided on the common optical path;
A second focusing unit provided on at least one of an optical path of the SLO measurement light branched from the common optical path, and an optical path of the OCT measurement light branched from the common optical path;
The fundus imaging device according to any one of claims 1 to 4, comprising: First focus means provided on the common optical path;
A second focusing unit provided on an optical path of the SLO measurement light branched from the common optical path,
The second focusing means includes:
The fundus imaging apparatus according to claim 2, wherein the fundus imaging apparatus is provided between a light source that emits the SLO measurement light and the light guide unit. The second focusing means includes:
The fundus imaging device according to claim 6, wherein the SLO measurement light is provided on an optical path that shares at least a part of an optical path of the return light reflected by the subject's eye and an optical path of the SLO measurement light. . Control means for controlling the OCT measurement light and the SLO measurement light to be focused on a predetermined position of the subject's eye via the first focus means and the second focus means,
The control means includes:
8. The method according to claim 6, wherein the first focus means controls the focus of the OCT measurement light and the SLO measurement light, and then the second focus means controls the focus of the SLO measurement light. A fundus imaging device according to any one of the preceding claims. First focus means provided on the common optical path;
A second focusing unit provided on an optical path of the OCT measurement light branched from the common optical path,
The second focusing means includes:
The fundus imaging apparatus according to any one of claims 2 to 4, wherein the fundus imaging apparatus is provided between a light source that emits the OCT measurement light and the light guiding unit. The second focusing means includes:
The fundus imaging device according to claim 9, wherein the fundus imaging device is provided between the chromatic aberration correction unit and the light guide unit. Control means for controlling the OCT measurement light and the SLO measurement light to be focused on a predetermined position of the subject's eye via the first focus means and the second focus means,
The control means includes:
11. The method according to claim 9, wherein, after controlling the focus of the OCT measurement light and the SLO measurement light by the first focus means, the focus of the OCT measurement light is controlled by the second focus means. 12. A fundus imaging device according to any one of the preceding claims.   The fundus imaging apparatus according to claim 5, wherein a focus adjustment range of the second focus unit is smaller than a focus adjustment range of the first focus unit. The OCT optical system has a lens,
The chromatic aberration correction unit includes:
The fundus imaging apparatus according to claim 1, wherein the correction includes correction of chromatic aberration of the lens. The chromatic aberration correction unit includes:
The fundus imaging apparatus according to any one of claims 1 to 13, wherein a focus position on the fundus of the subject's eye is aligned with respect to a wavelength band of the OCT measurement light. First scanning means provided on the common optical path, for scanning the OCT measurement light and the SLO measurement light in a first direction perpendicular to an optical axis;
A second scanning unit provided in an optical path of the OCT measurement light branched from the common optical path and scanning the OCT measurement light in a second direction perpendicular to the optical axis and the first direction;
15. The scanning device according to claim 1, further comprising: third scanning means provided in an optical path of the SLO measurement light branched from the common optical path and scanning the SLO measurement light in the second direction. The fundus imaging device according to claim 1. An OCT optical system that acquires tomographic information of the subject's eye using the OCT measurement light,
An SLO optical system that acquires fundus information of the eye using the SLO measurement light,
A common optical path that shares at least a part of the optical path of the OCT measurement light and the optical path of the SLO measurement light;
A chromatic aberration corrector provided in an optical path of the OCT measurement light branched from the common optical path, for correcting chromatic aberration in the eye to be inspected;
First focus means provided on the common optical path;
A second focusing means provided on an optical path of the SLO measurement light branched from the common optical path, and a fundus imaging method using a fundus imaging apparatus having:
A first step of adjusting the focus of the OCT measurement light and the SLO measurement light by the first focusing means;
A second step of adjusting the focus of the SLO measurement light by the second focusing means after the first step. An OCT optical system that acquires tomographic information of the subject's eye using the OCT measurement light,
An SLO optical system that acquires fundus information of the eye using the SLO measurement light,
A common optical path that shares at least a part of the optical path of the OCT measurement light and the optical path of the SLO measurement light;
A chromatic aberration corrector provided in an optical path of the OCT measurement light branched from the common optical path, for correcting chromatic aberration in the eye to be inspected;
First focus means provided on the common optical path;
A second focus unit provided in an optical path of the OCT measurement light branched from the common optical path, and a fundus imaging method using a fundus imaging apparatus,
A first step of adjusting the focus of the OCT measurement light and the SLO measurement light by the first focusing means;
A second step of adjusting the focus of the OCT measurement light by the second focusing means after the first step.   A program for causing a computer to execute each step according to claim 16 or 17.

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