JP7179523B2 - Fundus imaging device, fundus imaging method and program - Google Patents

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 ophthalmologic apparatus, an apparatus such as an OCT (Optical Coherence Tomography) apparatus or an SLO (Scanning Laser Ophthalmoscope) apparatus that scans illumination light to capture an image of the fundus 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 tomographic image of the fundus and a plane image of the fundus can be acquired in a single examination, and the efficiency of the examination can be improved.

By the way, in the OCT apparatus, the wider the wavelength band of the measurement light, the better the resolution in the depth direction. However, when the wavelength band is widened, the difference in the focal position on the fundus depending on the wavelength of the measurement light becomes large 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 becomes shallow in an adaptive optics OCT apparatus, the influence of the difference in 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 an adaptive optics OCT apparatus, it is important to correct chromatic aberration of the eye to be examined and the optical system of the apparatus.

In order to address such a problem, Patent Document 2 proposes an ophthalmologic apparatus having a lens for correcting chromatic aberration of an eye to be examined. The ophthalmologic apparatus of Patent Document 2 discloses a configuration in which a lens intentionally having chromatic aberration opposite to that of the subject's eye is arranged immediately in front of the subject's eye.

JP 2015-221091 A Japanese Patent Publication No. 2007-521866

However, in the configuration in which a lens for correcting chromatic aberration is placed immediately in front of the subject's eye in Patent Document 2, it is applied to a configuration in which a plurality of optical systems such as an OCT optical system and an SLO optical system are combined as in Patent Document 1. new problems arise. Specifically, since the OCT optical system and the SLO optical system have different wavelength bands, the lens configuration becomes complicated if chromatic aberration is to be corrected for all wavelength bands. Further, if the lens is configured to correct chromatic aberration only for the wavelength band of the OCT optical system, there is a risk of adversely affecting the optical performance of other optical systems such as the SLO optical system.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems described above, and an object of the present invention is to correct chromatic aberration of an eye to be examined in a configuration having an OCT optical system and an SLO optical system.

The fundus imaging apparatus of the present invention includes an OCT optical system for obtaining tomographic information of an eye to be examined using OCT measurement light, an SLO optical system for obtaining fundus information of the eye to be examined using SLO measurement light, and the OCT measurement. A common optical path composed of a reflecting optical system that shares at least part of the optical path of the light and the optical path of the SLO measurement light, and return light of the OCT measurement light branched by branching means provided in the common optical path. and a chromatic aberration corrector provided in the optical path of the OCT measurement light branched from the common optical path and correcting chromatic aberration in the eye to be examined.

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

1 is a diagram showing an example of the configuration of a fundus imaging device according to a first embodiment; FIG. FIG. 2 is a diagram schematically showing imaging ranges of an OCT optical system and an SLO optical system; 4 is a flowchart showing an example of a fundus imaging procedure according to the first embodiment; FIG. 10 is a diagram showing an example of the configuration of a fundus imaging apparatus according to a second embodiment; FIG. 10 is a flow chart showing an example of a fundus imaging procedure according to the second embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions of components, etc. described in the following embodiments are arbitrary and can be changed according to the configuration of the device to which the present invention is applied or various conditions.
In the following description, 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>
A fundus imaging apparatus 100 according to a first embodiment of the present invention, which is used to obtain an image of the fundus of an eye to be examined, etc., will be described with reference to FIGS. 1 to 3. FIG.
(Device configuration)
FIG. 1 is a diagram showing an example of the configuration of a fundus imaging apparatus 100. As shown in FIG.
The fundus imaging apparatus 100 is provided with an OCT optical system, an SLO optical system, an anterior eye observation optical system, a fixation lamp optical system, and a controller 190 (control means). In addition, in the present embodiment, the entire optical system is mainly composed of a reflecting optical system using mirrors.
The control unit 190 may be configured using a general-purpose computer, or may be configured as a dedicated computer for the fundus imaging apparatus 100 . Note that the control unit 190 may be configured separately from, or integrally with, the imaging unit including the OCT optical system, the SLO optical system, the anterior eye observation optical system, and the fixation lamp optical system.

First, the OCT optical system of the fundus imaging apparatus 100 will be described.
A light source 101 is a light source for generating light (low coherent light). Light source 101 corresponds to an example of an OCT light source. In this 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 the SLD, and any light source capable of emitting low coherent light may be used, such as ASE (Amplified Spontaneous Emission). The light source 101 is connected to and controlled by the controller 190 .

The wavelength of the light emitted from the light source 101 can be set to a wavelength corresponding to near-infrared light in view of eye measurement. Also, the wavelength of the light emitted from the light source 101 affects the lateral resolution of the obtained tomographic image, so the wavelength can be as short as possible. In this embodiment, the center wavelength is 830 nm. However, other wavelengths 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 central 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 splitting means. The light emitted from the light source 101 is split by the optical coupler 141 at an intensity ratio of 90:10 to become the reference light 103 and the OCT measurement light 104, respectively. However, the division ratio is not limited to this case, and can be appropriately selected according to the object to be inspected.

Next, the optical path of the reference light 103 will be explained. 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 is transmitted through the dispersion compensating glass 159 and guided by the mirrors 111 and 112 to the mirror 124 which is a reference mirror. In this embodiment, a plane mirror is used as the reference mirror. The light reflected by the mirror 124 is sequentially reflected again by the mirrors 112 and 111 , passes through the dispersion compensating glass 159 , and is guided to the optical coupler 141 .

The dispersion compensating glass 159 can compensate the reference light 103 for the dispersion of the OCT measurement light 104 when the OCT measurement light 104 reciprocates between the eye E and the lenses 154 and 11 .
The mirror 124 is mounted on the motorized stage 125 to constitute optical path length adjusting means. The motorized stage 125 is movable in the optical axis direction of the reference beam 103 as indicated by an arrow. By moving the electric stage 125, the position of the mirror 124 can be moved, and the optical path length of the reference light 103 can be adjusted. Note that the electric stage 125 is controlled by the control section 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 second optical means. The OCT measurement light 104 emitted as parallel light passes through the chromatic aberration correction lens 10 . The chromatic aberration correction lens 10 corresponds to an example of chromatic aberration correction means.

The chromatic aberration correction 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. ing. In the chromatic aberration correction lens 10, the plano-convex lens 10a is made of a glass type with lower dispersion, the plano-concave lens 10b is made of a glass type with higher dispersion, and the refractive indices of the plano-convex lens 10a and the plano-concave lens 10b are made substantially the same. By using such a shape and glass type, only chromatic aberration can be corrected without affecting the arrangement of other optical elements in 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. Also, it may be a biconvex lens, a biconcave lens, or a cemented lens of a meniscus lens. In this case, the combined refractive power of the lens 154 and the chromatic aberration correction lens 10 may be used to emit the OCT measurement light 104 as parallel light. A cemented lens of three or more lenses such as a plano-concave lens, a biconvex lens, and a plano-concave lens may also be used. In this case, a larger amount of chromatic aberration can be corrected with one chromatic aberration correction lens. Also, two or more chromatic aberration correction lenses may be arranged in the optical path. In this case, an even greater amount of chromatic aberration can be corrected.

Here, the chromatic aberration correction lens 10 of the present embodiment is arranged in a dedicated optical path for the OCT measurement light branched from the common optical path for the OCT measurement light and the SLO measurement light. Since the SLO measurement light and the OCT measurement light use different wavelengths, the effects of chromatic aberration on the subject's eye E are different. In addition, since the OCT optical system widens the wavelength band in order to increase the resolution in the depth direction, the effect of the chromatic aberration of the subject's eye E is greater than in the SLO optical system. Therefore, by arranging the chromatic aberration correction lens 10 in the optical path of the OCT measurement light, it is possible to suppress the influence of the chromatic aberration of the subject's eye E on the OCT optical system without affecting the optical performance of the SLO optical system. .

The OCT measurement light 104 is then emitted toward the dichroic mirror 177 and transmitted through the dichroic mirror 177 . The dichroic mirror 177 transmits or reflects light depending on the wavelength of the light. The dichroic mirror 177 is an example of light guiding means for guiding the OCT measurement light 104 and the SLO measurement light 106 to a common optical path. Also, 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 lead it to a common optical path.
The OCT measurement light 104 that has passed through the dichroic mirror 177 passes 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 aberration correction means. The deformable mirror 182 corrects the aberration between the OCT measurement light 104 and the OCT return light 105 by freely deforming the shape of the mirror based on the aberration detected by the wavefront sensor 181 . The wavefront sensor 181 corresponds to an example of aberration measuring means. For example, a Shack-Hartmann wavefront sensor can be used as the wavefront sensor 181 .
The aberration correction is not limited to the use of the deformable mirror 182. For example, a spatial light phase modulator using liquid crystal may be used. Further, the measurement of aberration is not limited to the case of using the wavefront sensor 181, and for example, any known sensor or the like may be used. Deformable mirror 182 and wavefront sensor 181 are controlled by controller 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 second scanning means. The X scanner 132 can use, for example, a galvanomirror. The center of the OCT measurement light 104 is adjusted to coincide with the center of rotation 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 subject's eye E in a direction perpendicular to the optical axis. It should be noted that the X scanner 132 may be composed of, for example, any other deflection mirrors. The X scanner 132 is connected to and controlled by the controller 190 .

The OCT measurement light 104 reflected by the X scanner 132 is reflected by the dichroic mirror 174 and then by the mirrors 117-120 in sequence.
The mirrors 119 and 120 are mounted on the motorized stage 126 to constitute first focusing means. The motorized stage 126 is movable toward and away from the mirrors 118 and 121 as indicated by arrows. The motorized stage 126 is controlled by the controller 190 . Mirrors 119 and 120 are arranged in the common optical path of the OCT optical system and SLO optical system. Therefore, by moving the electric stage 126, the mirrors 119 and 120 can be moved to adjust the focus state of the OCT measurement light 104 and the SLO measurement light 106 corresponding to the diopter of the eye E to be examined.

In this embodiment, the moving 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 corresponding to the diopter range of the eye E to be inspected from -12D to +7D. . Note that the movement range of the electric stage 126 may be arbitrarily set according to a desired configuration.
Further, in this embodiment, the mirrors 119 and 120 as the first focusing means are configured by a badal optical system using a reflecting optical system. By using a reflective 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 mirrors 121 and 122 , enters the lens 11 , and enters the Y scanner 133 . The Y scanner 133 corresponds to an example of first scanning means. The Y scanner 133 can use, for example, a galvanomirror. Here, the lens 11 has a positive refractive power, and causes the light flux scanned by the X scanner 132 to enter the Y scanner 133 over a wider incident angle range. Therefore, the swing angle of the X scanner 132 can be kept small, and an increase in the size of the optical system between the X scanner 132 and the Y scanner 133 can be suppressed.
In addition, while securing the scanning range on the retina Er, the imaging magnification to the pupil Ep that is optically conjugate with the Y scanner 133 can be easily enlarged. be advantageous in ensuring Note that the chromatic aberration correction lens 10 described above may be configured to correct chromatic aberration of the lens 11 in addition to the chromatic aberration of the eye E to be examined. This makes it possible to further suppress the difference in focal position according to the wavelength on the fundus, which is advantageous for acquiring a high-resolution and high-quality fundus tomographic image. That is, the chromatic aberration correction lens 10 is configured to align the focal positions on the fundus for the wavelength band of the OCT measurement light.

The center of the OCT measurement light 104 is adjusted to coincide with the center of rotation 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 scanning direction of the X scanner 132 . Note that the Y scanner 133 may be configured by any other deflecting mirror. The Y scanner 133 is connected to and controlled by the controller 190 .
The X scanner 132 and the Y scanner 133 correspond to an example of OCT scanning means for scanning the fundus of the eye E to be inspected with the OCT measurement light 104 in two-dimensional directions.

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

The reference light 103 and the OCT return light 105 are combined 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 and the optical path length of the reference light 103 are substantially equal, the OCT return light 105 and the reference light 103 interfere with each other and become interference light. . The control unit 190 controls the electric stage 125 to move the mirror 124 to match the optical path length of the reference light 103 with the optical path lengths of the OCT measurement light 104 and the OCT return light 105 that vary depending on the measured portion of the eye E to be examined. can be done. The combined light 108 (interference light) is emitted as spatial light from the single-mode fiber 144 and guided to the transmissive grating 161 through the lens 152 . After that, the light 108 is split into wavelengths by the transmission grating 161 , condensed by the lens 153 , and made 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, the line camera 191 observes interference fringes in the spectral region on the wavelength axis. The obtained voltage signal group is converted into a digital value. The control unit 190 can generate a tomographic image of the subject's eye E by performing data processing on the interference signal converted into a digital value. Known data processing for generating a tomographic image from an interference signal can be used for data processing for generating a tomographic image. The control unit 190 displays the generated tomographic image on a display unit (not shown). Any monitor, for example, can be used as the display unit. Further, the display section may be separate from the imaging section and the control section 190, or may be configured integrally.

The single mode fibers 142 and 143 are provided with polarization adjusting 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. can be The position where the polarization adjustment paddles 183 and 184 are provided is not limited to this case, and they may be provided on the single mode fiber 145 or the like.

By the way, the OCT return light 105 is split by the beam splitter 171 when returning along the optical path of the OCT measurement light 104 , and part of the light enters the wavefront sensor 181 . A wavefront sensor 181 measures the aberration of the incident OCT return light 105 . In this embodiment, the beam splitter 171 partially reflects the OCT return light 105 and transmits the SLO return light 107, which will be 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 controller 190 .

By applying the output from the wavefront sensor 181 to the Zernike polynomials, the control unit 190 grasps the aberration of the subject's eye E measured by the wavefront sensor 181 . The control unit 190 corrects the diopter of the subject's 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. Further, 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.

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

Next, the SLO optical system will be explained.
Light source 102 generates light of a different wavelength from light source 101 . Light source 102 corresponds to an example of an SLO light source. In this embodiment, an SLD with a wavelength of 780 nm is used as the light source 102 . However, the light source 102 is not limited to the SLD, and an LD (Laser Diode) or the like may be used. Also, 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 and controlled by the controller 190 .

Light emitted from the light source 102 is guided to the lens 155 and emitted as parallel light. The light that has passed through the lens 155 is guided to the beam splitter 172 and split at an intensity ratio of 90:10 between the transmitted light and the reflected light (SLO measurement light 106). SLO measurement light 106 reflected by beam splitter 172 passes through focus lens 157 and lens 158 .

The focus lens 157 is mounted on the motorized stage 127 to constitute a second focus means. The motorized stage 127 is movable in the optical axis direction of the SLO measurement light 106 as indicated by an arrow. The motorized stage 127 is controlled by the controller 190 . The focus lens 157 is arranged not in the common optical path of the OCT optical system and the SLO optical system, but in the dedicated optical path of the SLO optical system. Therefore, by moving the electric stage 127, the focus lens 157 is moved, 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 controlling the electric stage 127 to move the focus lens 157 .

In this embodiment, the moving range of the motorized stage 127 is 10 mm, and this moving range corresponds to the diopter range of -2D to +2D. Note that the movement range of the motorized stage 127 is not limited to this case, and can be set to an arbitrary movement range narrower than the movement range of the motorized stage 126 .
In the present embodiment, the focus adjustment range of the second focusing means is narrowed in order to adjust the focus of the OCT measurement light 104 and the SLO measurement light 106 using the first focusing means and to correct the dioptric power of the subject's eye E. can be suppressed. That is, the moving range of the motorized stage 127 can be made smaller than the moving range of the motorized stage 126 . Therefore, a small stage can be used to adjust the focal positions of the OCT optical system and the SLO optical system to different positions, so that the optical system can be made compact.

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

The light transmitted through focus lens 157 and lens 158 is emitted toward dichroic mirror 177 and reflected by dichroic mirror 177 . The SLO measurement light 106 reflected by the dichroic mirror 177 passes through the common optical path with the OCT measurement light 104 and enters the dichroic mirror 173 . Here, the common optical path of the SLO measurement light 106 and the OCT measurement light 104 includes an optical path via dichroic mirror 177, beam splitter 171, mirrors 113 and 114, deformable mirror 182, mirrors 115 and 116 and 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 third scanning means. The X scanner 131 can use, for example, a resonance mirror. The center of the SLO measurement light 106 is adjusted to coincide with the center of rotation of the X scanner 131 . By rotating the X scanner 131, the SLO measurement light 106 can be used to scan the retina Er in a direction perpendicular to the optical axis. The X scanner 131 is connected to and controlled by the controller 190 .
The X scanner 131 and the Y scanner 133 correspond to an example of SLO scanning means for scanning the fundus of the eye E to be inspected with the SLO measurement light 106 in two-dimensional directions.

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. is. The scanning speed of the OCT measurement light 104 is limited by the readout speed of the line camera 191 . On the other hand, by positioning the X scanner 132 for the OCT measurement light 104 and the X scanner 131 for the SLO measurement light 106 at different positions, the scan speed of the SLO measurement light 106 does not depend on the OCT scan speed. can be raised. Therefore, it is possible to improve the frame rate when obtaining a fundus plane image using the SLO optical system. It should be noted that the X-scanner 131 may be configured with any deflection mirrors depending on the desired configuration.

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

When the SLO measurement light 106 enters the subject's eye E, it is reflected or scattered by the retina Er, returns as SLO return light 107 along the optical path of the SLO measurement light 106, is reflected by the dichroic mirror 177, and then passes through the beam splitter 172. . The SLO return light 107 transmitted through the beam splitter 172 is collected 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 acts as a confocal stop for shielding 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 . For example, an APD (Avalanche Photo Diode) is used for the light receiving element 192 . However, any other light receiving element may be used as the light receiving element 192 depending on the 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 a digital value and generate a fundus plane image. For the data processing for generating the fundus plane image, known data processing for generating the fundus plane image from the output signal from the light receiving element 192 can be used. The control unit 190 displays the generated fundus plane image on a display unit (not shown).

Next, the fixation lamp optical system will be described.
The fixation light optical system consists of a dichroic mirror 175 and a fixation light panel 194 .
Dichroic mirror 175 reflects visible light from fixation lamp panel 194 and transmits light from light source 101 and light source 102 according to the wavelength of the light. Therefore, the pattern displayed on the fixation lamp panel 194 is projected onto the retina Er of the subject's eye E via the dichroic mirror 175 . By displaying a desired pattern on the fixation light panel 194, the fixation direction of the eye E to be examined can be specified, and the range of the retina Er to be imaged can be set. An organic EL panel, for example, is used for the fixation lamp panel 194 . However, fixation light panel 194 may be another display. The fixation light panel 194 is connected to and controlled by the controller 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 anterior eye illumination light source (not shown).
The dichroic mirror 176 reflects infrared light from the anterior illumination light source and transmits visible light from the fixation lamp panel 194 and 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 match 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 to be examined E based on the output from the anterior eye observation camera 193 on the display unit and aligning it with the reference position, the X direction of the OCT optical system and the SLO optical system with respect to the eye to be examined E can be adjusted. and alignment in the Y direction. The anterior eye observation camera 193 is connected to the control unit 190 and controlled by the control unit 190 .

Further, the focus of the anterior eye observation camera 193 is adjusted so that the iris of the subject's eye E is in focus 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 and focusing on the iris in the image of the anterior segment on the display unit, it is possible to align the OCT optical system and the SLO optical system in the Z direction.
In this embodiment, an LED with a wavelength of 970 nm is used as the anterior eye illumination light source, and a CCD camera is used as the anterior eye observation camera 193 . However, the anterior eye illumination light source and the anterior eye observation camera are not limited to this case, and may be other light sources, imaging devices, and the like. The wavelength of the anterior illumination light source may also be varied depending on the desired configuration.

(Relationship of shooting range)
Next, 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 frame of the dashed line indicates the imaging range 210 of the SLO optical system. The relationship between an imaging range 220 of the OCT optical system and an imaging range 210 of the SLO optical system when imaging one line with the OCT optical system is schematically shown.
Since the OCT optical system and the SLO optical system have the Y scanner 133 arranged on the common optical path, they are simultaneously scanned in the Y direction (vertical direction on the paper surface of FIG. 2). On the other hand, in the X direction (horizontal direction of the paper surface of FIG. 2), scanning is performed using separate scanners, the X scanner 132 and the X scanner 131, so that the imaging ranges in the X direction of the OCT optical system and the SLO optical system are independent of each other. can be set to For example, in FIG. 2, the imaging range 220 of the OCT optical system is set substantially in the center of the imaging range 210 of the SLO optical system, but the relationship of the imaging ranges in the X direction is not limited to this case. The imaging range 220 of the OCT optical system may be set arbitrarily regardless of the imaging range 210 of the SLO optical system.

Also, since the resonance mirror of the X scanner 131 has a higher scanning speed than the galvanomirror of the X scanner 132, the SLO measurement light 106 is scanned multiple times in the X direction during one Y-direction scan. Therefore, for example, an imaging range (one line) of the OCT optical system having a length L can be imaged by m-point sampling (A-scan), and an L×L SLO imaging range can be imaged by m X-scans. . As a result, an L×L fundus plane image (two-dimensional image) can be obtained with the SLO optical system while a one-line tomographic image with a length L is captured with the OCT optical system. Note that the numerical values of L and m can be arbitrarily set according to the desired configuration.

Further, 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 the scanning position of the X scanner 132 is changed for capturing one line in the Y direction. and repeat. For example, by capturing m lines in a range of L in the X direction, an L×L 3D volume image can be obtained. In addition, during this period, the SLO optical system can be used to acquire m L×L fundus plane images.

(tracking procedure)
Next, a method of positional deviation correction (tracking) based on a fundus plane image acquired using the SLO optical system will be described.
In the tracking process of the present embodiment, the control unit 190 performs the first imaging when line tomographic images at the same position are captured 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 the fundus image based on the fundus information (second fundus information) acquired using the SLO optical system at the time of the second and subsequent imaging using the OCT optical system to the target image for positional deviation detection. and The control unit 190 calculates the displacement amount of the target image with respect to the reference image. Calculation of the positional deviation amount 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 positional deviation amount. Thereby, the control unit 190 can perform fundus tracking that corrects the deviation of the photographing position of the tomographic image based on the movement of the fundus due to the involuntary eye movement or the like. A plurality of acquired line tomographic images at the same position can be used for noise reduction processing of tomographic images by superimposition.

This fundus tracking can be similarly applied when acquiring 3D volume images using OCT optics. In this case, as described above, the OCT optical system is used to repeatedly acquire one line of tomographic images in the Y direction while changing the position in the X direction. At this time, the control unit 190 uses, as a reference image, the fundus plane image based on the fundus information of the subject's eye E acquired during the first (first line) imaging. In addition, the control unit 190 sets the fundus plane image based on the fundus information acquired during the second (second line) and subsequent imaging as the target image. The control unit 190 calculates the positional deviation amount between the reference image and the target image, and performs fundus tracking. As a result, even when acquiring a 3D volume image, it is possible to correct the deviation of the photographing position of the tomographic image with respect to the retina Er of the eye E to be examined.

As the reference image, the entire fundus plane image acquired using the SLO optical system at the time of the first imaging using the OCT optical system may be used, or a partial image of the fundus plane 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. Note that when a partial image of the fundus plane image is used as the target image, the acquisition interval of the target image can be shortened, and the control rate of the fundus tracking can be increased. Therefore, it becomes easier to correct positional deviation due to 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 becomes easy to ensure a large overlap region between the reference image and the target image even if the amount of positional deviation between the reference image and the target image is large. It becomes easier to correct the deviation. If the movement of the fundus is slow and the control rate of the fundus tracking has a margin, the image size of the target image may be set larger than the image size of the reference image. Even in this case, it becomes easier to correct the positional deviation due to a large movement of the fundus. In other words, by setting the image size of one of the reference image and the target image to be larger than the image size of the other, it becomes easier to correct positional deviation due to a large movement of the fundus.

(Procedure for photographing fundus)
Next, referring to FIG. 3, a procedure for photographing the fundus in the fundus imaging apparatus 100 will be described. FIG. 3 is a flowchart showing an example of a fundus imaging procedure. The processing of the flowchart of FIG. 3 is implemented by the control unit 190 executing a program stored in the memory.
In S301, the control unit 190 turns on an anterior eye illumination light source (not shown) 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 section 190 generates an image of the anterior segment of the subject's eye E based on the output of the anterior eye observation camera 193 and displays it on the display section.

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

In S303, the control unit 190 turns off the anterior eye illumination light source when the examiner again presses the anterior eye illumination light source button displayed on the display unit.
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, and may be turned on, for example, after rough focus adjustment in S305, which will be described later. After turning on the light source 102 of the SLO optical system, the control unit 190 generates a fundus plane image based on the output of the light receiving element 192 and displays it on the display unit.

In S305, the control unit 190 roughly adjusts the focus (rough focus adjustment) of the SLO optical system and the OCT optical system according to the examiner's input based on the fundus plane image displayed on the display unit.
Specifically, the examiner observes the fundus plane image and performs an operation to move 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. Motorized stage 126 and mirrors 119 and 120 are arranged in the common optical path of OCT measurement light 104 and SLO measurement light 106 . Therefore, by adjusting the focus of the SLO measurement light 106, rough focus adjustment of the OCT measurement light 104 is also performed at the same time. Here, focus adjustment is performed so that the brightness of the fundus plane image is maximized. At this time, the controller 190 places the motorized stage 127 of the SLO optical system at a preset initial position. Here, as the position of the motorized stage 127 in the initial state, the position of the motorized stage 127 is set such that the focus positions of the OCT measurement light 104 and the SLO measurement light 106 substantially coincide.

In S306, the control unit 190 performs XY fine alignment of the imaging unit with respect to the subject's eye E according to the examiner's input 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 adjusts the X direction and the Y direction of the photographing unit with respect to the eye to be examined E according to the examiner's input. Perform fine orientation alignment.
Here, the wavefront sensor 181 is adjusted so that the center position of the wavefront sensor 181 is aligned with 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 to be examined 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. The display unit may display an index or the like corresponding to the center position of the wavefront sensor 181 and the Hartmann image.

In S307, the control unit 190 starts 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 subject's eye E other than the defocus component. A known method can be used for aberration correction using the deformable mirror 182 .
A deformable mirror 182 is arranged in the common optical path of the OCT measurement light 104 and the SLO measurement light 106 . Therefore, by deforming the shape of the deformable mirror 182 for the OCT measurement light 104 to correct the aberration of the eye E to be examined, the aberration of the eye E to be examined can also be corrected for the SLO measurement light 106 .

In S<b>308 , the control unit 190 starts wavefront correction and then adjusts the optical path length of the reference light 103 . Specifically, the examiner performs an operation of moving a reference light 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 a tomographic image acquired using the OCT optical system on the display unit, and according to an input by the examiner, an image of a desired layer in the tomographic image is displayed within the tomographic image display area. The optical path length of the reference beam 103 is adjusted so as to match the desired position.

In 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 the OCT optical system with high lateral resolution, the NA (Numerical Aperture) of the measurement light at the fundus is large and the focal depth is shallow, so it is difficult to simultaneously focus the entire depth direction of the retina Er. Therefore, in S309, fine focus adjustment is performed so that the OCT measurement light 104 is focused on the layer of the retina Er that is particularly desired to be imaged. For example, when imaging blood vessels on the surface of the retina, the control unit 190 controls the motorized stage 126 to adjust the focus of the OCT measurement light 104 so that the brightness of that portion is maximized. After adjusting the OCT measurement light 104 to a desired focus state by fine focus adjustment, the process proceeds to S310.

In S310, the control unit 190 performs 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 photoreceptors of the fundus plane image displayed on the display unit is increased. Note that the position where the SLO optical system is focused is not limited to the photoreceptors. The position at which the SLO optical system is focused may be a position having other feature points such as a blood vessel if the desired tracking accuracy can be achieved.

A focus lens 157 mounted on the motorized stage 127 is arranged in a dedicated optical path for the SLO optical system branched from the 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 arranged on a common optical path that shares at least 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 on 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 .
The focus adjustment of the SLO optical system can also be performed by moving the lens 155 arranged in the dedicated optical path of the SLO measurement light 106 and the lens 156 arranged in the dedicated optical path of the SLO return light 107 in the optical axis direction. can. However, in that case, it is necessary to control the positions of the lenses 155 and 156 respectively, which complicates the device configuration and control. In contrast, when the focus lens 157 is used to adjust the focus of the SLO optical system, 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 positional deviation amount 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 deviation amount. Fundus tracking is performed by Therefore, the control unit 190 functions as eye movement detection means. By tracking the fundus, it is possible to obtain a plurality of tomographic images used for noise processing by superimposing tomographic images, a moving image, a 3D volume image, etc., while suppressing displacement.

In S312, the control unit 190 starts tracking, and acquires a fundus tomographic image and a fundus planar image in response to the examiner pressing an imaging button (not shown) displayed on the display unit. Interference light (light 108) between OCT measurement light 104 and reference light 103 is received by line camera 191 and converted into a voltage signal. Furthermore, 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. Also, the SLO return light 107 is received by the light receiving element 192 and converted into a voltage signal. Furthermore, 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 this embodiment, while performing accurate fundus tracking using a planar image of the fundus acquired by the SLO optical system, by focusing on a desired layer of the retina Er using the OCT optical system, SN images can be obtained with high resolution. A tomographic image of the fundus with a good ratio can be taken. In addition, since aberration fluctuation due to movement of the focus lens 157 in the SLO optical system does not affect the OCT optical system, a fundus tomographic image can be acquired using the OCT optical system while maintaining accurate aberration correction.

As described above, the fundus imaging apparatus 100 of the present embodiment acquires the fundus information of the eye E using the OCT optical system that acquires the tomographic information of the eye E to be examined using the OCT measurement light 104 and the SLO measurement light 106. and an SLO optical system for acquisition. In addition, the fundus imaging apparatus 100 includes a common optical path that shares at least 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 eye to be examined branches from the common optical path. provided in the optical path of the OCT measurement light 104 . Specifically, the chromatic aberration correction lens 10 is provided on the side of the light source 101 that emits the OCT measurement light 104, which is 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 chromatic aberration of the subject's eye E tends to have a greater influence than the SLO measurement light 106, the chromatic aberration of the subject's eye is corrected 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 acquired. On the other hand, since the chromatic aberration correction 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.

In addition, the fundus imaging apparatus 100 has a dichroic mirror 177 as light guide means for guiding the OCT measurement light 104 and the SLO measurement light 106 to a common optical path. is provided between 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 compared to the configuration in which the chromatic aberration correction lens 10 is provided by branching the common optical path.

The fundus imaging apparatus 100 also includes a badal optical system composed of mirrors 119 and 120 provided in a common optical path, and a focus lens 157 in the optical path of the SLO measurement light 106 branched from the common optical path. Here, the focus adjustment range of the focus lens 157 is narrower than the focus adjustment range of the Badal optical system.
The fundus imaging apparatus 100 also 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 the common optical path. The controller 190 controls the shape change 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 on the fundus in two-dimensional directions. The control unit 190 detects the fundus movement based on the fundus information of the subject's eye E acquired using the SLO optical system, and controls the X scanner 132 and the Y scanner 133 based on the detected fundus movement.
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 a layer to be imaged, and the focal position of the SLO optical system can be adjusted to a layer with many feature points that is advantageous for position detection for fundus tracking. can. Therefore, while highly accurate fundus tracking is performed using the SLO optical system, a tomographic image with high lateral resolution can be captured with the OCT optical system. Therefore, it is possible to obtain a plurality of tomographic images, moving images, and 3D volume images while suppressing positional deviation during imaging.

The fundus imaging apparatus 100 also 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 a Y scanner 133 that scans the OCT measurement light 104 in the X direction (second direction) perpendicular to the Y direction. direction). The fundus imaging apparatus 100 also 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 the X scanner 132 performs one scan. Further, the control unit 190 causes the X scanner 131 to repeatedly scan the SLO measurement light 106 while the Y scanner 133 performs one scan.
The common optical path of the OCT optical system and SLO optical system also includes a dichroic mirror 173 that separates the OCT measurement light 104 and SLO measurement light 106 . Further, the common optical path comprises a dichroic mirror 174 that combines OCT measurement light 104 and SLO measurement light 106 separated by dichroic mirror 173 . Here, the X scanner 132 is arranged in the optical path of the OCT measurement light 104 separated by the dichroic mirror 173, and the X scanner 131 is arranged in 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 configuration can be made more compact than when the Y scanner is provided separately for each optical system. can. In addition, since the fundus imaging apparatus 100 uses separate X scanners for the X scanner 132 and the X scanner 131, the imaging ranges in the X direction of the OCT optical system and the SLO optical system can be set independently. Furthermore, 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 cycles, and the scanning speed of the measurement light in the SLO optical system is equal to the scanning speed of the measurement light in the OCT optical system. can be faster than

<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 showing an example of the configuration of the fundus imaging device 400. As shown in FIG. Here, differences from the fundus imaging device 100 of the first embodiment will be mainly described, and the same reference numerals will be used for the same configuration as the fundus imaging device 100 of the first embodiment, and description thereof will be omitted. .
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 means is not arranged in the dedicated optical path of the SLO optical system, but the second focusing means is arranged in the dedicated optical path of the OCT optical system. In the fundus imaging apparatus 400, a focus lens 457 is arranged as a second focus means in the dedicated optical path of the OCT optical system branched from the common optical path of the OCT optical system and the SLO optical system.

In this embodiment, a focus lens 457 and a lens 458 are provided between the chromatic aberration correction lens 10 and the dichroic mirror 177 on the optical path of the OCT measurement light 104 . Here, by providing the focus lens 457 after the chromatic aberration correction lens 10, the chromatic aberration of the subject's eye can be corrected without being affected by changes in the luminous flux due to the focus state. A focus lens 457 is mounted on the motorized stage 427 . The motorized stage 427 is movable in the optical axis direction of the OCT measurement light 104 as indicated by an arrow. The motorized stage 427 is controlled by the controller 190 .

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

(Procedure for photographing fundus)
Next, referring to FIG. 5, a procedure for photographing the fundus in the fundus imaging device 400 will be described. FIG. 5 is a flow chart showing an example of a fundus photographing procedure. The processing of the flowchart of FIG. 5 is realized by executing the program stored in the memory by the control unit 190 . Note that S501 to S507 are the same as S301 to S307 in the photographing procedure according to the first embodiment, so description thereof will be omitted.
When imaging is started and alignment, rough focus adjustment, and wavefront correction are started in steps S501 to S507 in the same manner as in steps S301 to S307 in the first embodiment, the process proceeds to step S508.

In S508, the control unit 190 performs fine focus adjustment of the SLO optical system. Specifically, the examiner performs an operation to move 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 photoreceptors of the fundus plane image displayed on the display unit is increased. Note that the position where the SLO optical system is focused is not limited to the photoreceptors. The position at which the SLO optical system is focused may be a position having other feature points such as a blood vessel if the desired tracking accuracy can be achieved.
Also, at this time, the control unit 190 places the motorized stage 427 of the OCT optical system at a preset initial position. 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 S509, the control unit 190 starts fundus tracking as in 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 S511, the control unit 190 performs 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 brightness of the layer desired to be imaged in the tomographic image displayed on the display unit is maximized.

In this embodiment, the focus lens 457 is arranged in the dedicated optical path of the OCT optical system branched from the 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 S512, the control unit 190 performs imaging in the same procedure as in S312 of the first embodiment.
As described above, the fundus imaging apparatus 400 of the present embodiment is provided with the focus lens 457, which is the second focus means, in the optical path of the OCT measurement light 104 branched from the common optical path. In other words, the focal positions of the OCT optical system and the SLO optical system can be adjusted to different positions while maintaining a compact device configuration. Therefore, the fundus imaging device 400 according to the present embodiment performs high-accuracy fundus tracking while focusing on a desired layer with the OCT optical system to achieve high resolution. You can shoot. In addition, 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. This makes the operation easier, for example, when shooting

<Modification 1>
In the first and second embodiments, the mirrors 119 and 120 mounted on the motorized stage 126 arranged in the common optical path of the OCT optical system and the SLO optical system are used as the first focusing means, and by moving these mirrors, rough images can be obtained. Focus adjustment and fine focus adjustment were performed. However, the first focusing means used for these focus adjustments is not limited to the configuration described above. For example, a deformable mirror 182 arranged in the common optical path of the OCT optical system and the SLO optical system can be used as the first focusing means.
In particular, 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. Thereby, the focus positions of the OCT optical system and the SLO optical system can be changed while correcting the aberration of the eye E to be examined. Also in rough focus adjustment, the deformable mirror 182 can be similarly used when the focus adjustment amount is small.
Also, as the first focusing means, any other focusing means such as a focus lens, an electro-optical element, a piezo element, a liquid crystal optical element, or a deformable mirror may be used.

<Modification 2>
Further, in the first and second embodiments, focus adjustment is performed by independently controlling the first focusing means and the second focusing means. It may have a mode for interlocking and controlling the focus means.
The device configuration in this case is the same as the fundus imaging device 100 shown in FIG. 1, and the procedure for photographing the fundus is the same as the flowchart in FIG. However, it differs in that the first focus means and the second focus means are interlocked and controlled at the time of OCT fine focus adjustment (S511).

In this case, in S508, the control unit 190 controls the motorized stage 126 to move the focus lens 157 to perform fine focus adjustment of the SLO optical system. After that, in S511, when the motorized stage 126 is moved to perform OCT fine focus adjustment, the motorized stage 127 arranged in the dedicated optical path of the SLO optical system is controlled so as to operate in the direction of canceling the adjustment by the motorized stage 126. do. In other words, at the time of OCT fine focus adjustment by the first focusing means arranged in the common optical path, the control unit 190 shifts the second focusing means arranged in the dedicated optical path to the first focusing means in the direction of canceling the influence of the adjustment. It is operated in conjunction with the focusing means. Thereby, the focus of the OCT optical system can be adjusted without changing the focus state of the SLO optical system.

After that, when the brightness of the desired layer is maximized by the OCT fine focus adjustment, the control unit 190 performs photographing as in S312 in the first embodiment.
Even in this case, it is possible to capture a high-resolution image with a good SN ratio by focusing on a desired layer with the OCT optical system while performing accurate fundus tracking. In addition, since the focus of the OCT optical system can be changed to a different layer while the fundus tracking is being performed using the SLO optical system, the operation is facilitated when, for example, imaging is performed at a plurality of focus positions. In addition, since aberration fluctuation due to movement of the focus lens 157 mounted on the motorized stage 127 does not affect the OCT optical system, a fundus tomographic image can be acquired using the OCT optical system while performing accurate aberration correction. In addition, in the configuration of the fundus imaging apparatus 400, similar processing can be performed when performing the fundus imaging procedure described in the flowchart of FIG.

Note that focus adjustment may be performed by deforming the deformable mirror 182 as the first focusing means. 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, which is the second focusing means, so as to cancel the offset amount.
Further, an interlocking mechanism for interlocking the first focusing means and the second focusing means may be provided. In this case, the control unit 190 can interlock the first focusing means and the second focusing means by controlling the interlocking mechanism. Further, the interlocking mechanism may be configured to be able to release the interlocking between the first focusing means and the second focusing means. The second focusing means can be controlled separately.

<Modification 3>
Further, when performing rough focus adjustment in S305 of the first embodiment and S505 of the second embodiment, the adjustment of the optical path length by the optical path length adjusting means provided in the reference optical path and the focus adjustment by the first focusing means are performed. They may be controlled in conjunction with each other.
In this case, the controller 190 controls the motorized stage 125 to move the mirror 124 so that the optical path length changes by approximately the same amount as the optical path length change due to the movement of the mirrors 119 and 120 during 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, it is possible to keep the amount of movement of the mirror 124 small when adjusting the reference optical path length in S308 of the first embodiment and S510 of the second embodiment. If the amount of movement 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 operation to the completion of 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, the control unit 190 can interlock the mirror 124 mounted on the electric stage 125 and the first focusing means by controlling the interlocking mechanism. Further, the interlocking mechanism may be configured to be able to release the interlocking between the optical path length adjusting means and the first focusing means. One focusing means can be controlled separately.
In the first and second embodiments, the case where the optical path length adjusting means is configured by the mirror 124 provided in the optical path of the reference light 103 has been described, but this is not the only case, and the optical path length adjusting means may be an OCT. It may be provided in the optical path of the measurement light 104 .

<Modification 4>
In the first and second embodiments, the case where the second focusing means is provided in 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 focusing means may be provided in 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 focusing means has a narrower focus adjustment range than the first focusing means and a narrow diopter range of the subject's eye E that can be handled. Therefore, the second focusing means is used for fine focus adjustment of each optical system. . Therefore, in this modified example, in the imaging procedure, fine focusing after rough focusing is performed separately by the second focusing means respectively provided in the dedicated optical path of the OCT optical system and the dedicated optical path of the SLO optical system.
Even in such a case, the second focusing means has a narrower focus adjustment range than the first focusing means. Therefore, the device configuration can be made compact. Also, the second focusing means is not limited to an electric stage equipped with a focusing lens. For example, the second focusing means may be composed of an electro-optical element such as a crystal of potassium tantalate niobate, other piezoelectric element capable of obtaining the same effect, a liquid crystal optical element, a deformable mirror, or the like. . In this case, since it is not necessary to secure the moving range of the motorized stage, the device configuration can be made more compact.

<Other Modifications>
In addition, in the above-described embodiment and modified example, the case where the control unit 190 performs various alignments, optical path length adjustment, and focus adjustment according to input from the examiner has been described. However, based on the above-described various alignments, the optical path length adjustment, the anterior segment image, the fundus plane image, the Hartmann image, the tomographic image, etc. used in the focus adjustment, the control unit 190 automatically performs 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 brightness of the fundus plane image, the layer to be photographed, and the like, in the same manner as the alignment and adjustments described above.

Further, in the above-described embodiments and modifications, 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 interferometric optical system of the fundus imaging device may have the configuration of a Mach-Zehnder interferometer. Further, in the above-described embodiments and modifications, the wavelength of the light reflected or transmitted by each dichroic mirror is arbitrary, and the configuration may be such that light is reflected or transmitted in a manner opposite to the configuration described above. .

Furthermore, in the above-described embodiments and modifications, the OCT optical system and the SLO optical system share the Y scanner 133, but separate Y scanners may be provided for the OCT optical system and the SLO optical system. Also, the first focusing means arranged in the common optical path is not limited to being 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 means. Also, the Y scanner 133 may not be provided between the eye E to be examined and the first focusing means.

Furthermore, in the above-described embodiments and modifications, the OCT optical system is configured as a spectral domain OCT (SD-OCT) optical system using an SLD as a light source, but it is not limited to this. Any other kind of OCT optical system can be applied, such as a wavelength-swept OCT (SS-OCT) optical system using a wavelength-swept light source capable of sweeping the wavelength of the emitted light.

<Other embodiments>
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.
Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above-described embodiments. The present invention includes inventions modified within the scope 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 gist of the present invention. Moreover, not all combinations of features described in each embodiment and modifications are essential for the solution means 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 an eye to be examined using OCT measurement light;
an SLO optical system that acquires fundus information of the eye to be inspected using SLO measurement light;
a common optical path composed of a reflective optical system that shares at least part of the optical path of the OCT measurement light and the optical path of the SLO measurement light;
measuring means for measuring the wavefront of the return light of the OCT measurement light branched by the branching means provided in the common optical path;
chromatic aberration correcting means provided in the optical path of the OCT measurement light branched from the common optical path and correcting chromatic aberration in the eye to be examined;
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 means is
2. The fundus imaging apparatus according to claim 1, wherein the fundus imaging apparatus is provided between the light source for emitting the OCT measurement light and the light guide means. The light guide means
3. The fundus imaging apparatus according to claim 2, wherein the first optical means transmits one of the OCT measurement light and the SLO measurement light and reflects the other measurement light. splitting means for splitting the light emitted from the light source into the OCT measurement light and the reference light;
a second optical means for collimating the OCT measurement light split by the splitting means;
The chromatic aberration correction means is
4. The fundus imaging apparatus according to claim 2, wherein the fundus imaging apparatus is provided between the second optical means and the light guide means. a first focusing means provided in the common optical path;
a second focusing means provided in 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 apparatus according to any one of claims 1 to 4, characterized by comprising: a first focusing means provided in the common optical path;
a second focusing means provided in the optical path of the SLO measurement light branched from the common optical path;
The second focusing means is
5. 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 SLO measurement light and the light guide means. The second focusing means is
7. The fundus imaging apparatus according to claim 6, wherein the apparatus is provided in an optical path that shares at least part of an optical path of the SLO measurement light and an optical path of return light reflected by the eye to be inspected from the SLO measurement light. . a control means for controlling such that the OCT measurement light and the SLO measurement light are focused on a predetermined position of the eye to be inspected via the first focus means and the second focus means;
The control means is
8. The method according to claim 6, wherein the focus of the SLO measurement light is controlled by the second focus means after the focus of the OCT measurement light and the SLO measurement light is controlled by the first focus means. The fundus imaging device described. a first focusing means provided in the common optical path;
a second focusing means provided in the optical path of the OCT measurement light branched from the common optical path;
The second focusing means is
5. The fundus imaging apparatus according to any one of claims 2 to 4, wherein the fundus imaging apparatus is provided between the light source for emitting the OCT measurement light and the light guide means. further comprising correction means for correcting the wavefronts of the OCT measurement light and the SLO measurement light based on the wavefronts measured by the measurement means;
The correcting means is
10. The fundus imaging apparatus according to any one of claims 1 to 9, which is provided between said branching means and said eye to be examined. a control means for controlling such that the OCT measurement light and the SLO measurement light are focused on a predetermined position of the eye to be inspected via the first focus means and the second focus means;
The control means is
10. The method according to claim 9, wherein after the focus of the OCT measurement light and the SLO measurement light is controlled by the first focus means, the focus of the OCT measurement light is controlled by the second focus means. Fundus imaging device. 10. The fundus imaging apparatus according to any one of claims 5 to 9, wherein a focus adjustment range of said second focus means is smaller than a focus adjustment range of said first focus means. a first scanning means provided on the common optical path for scanning the OCT measurement light in a first direction perpendicular to the optical axis;
a second scanning means provided on the common optical path for scanning the OCT measurement light in a second direction perpendicular to the optical axis and the first direction;
further comprising a lens having a positive refractive power provided between the first scanning means and the second scanning means;
13. The lens according to any one of claims 1 to 12, wherein the OCT measurement light scanned by the first scanning means is incident on the second scanning means in a wider incident angle range. 3. The fundus imaging device according to . The chromatic aberration correction means is
14. 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 for the wavelength band of the OCT measurement light. a third scanning means provided in the optical path of the SLO measurement light branched from the common optical path and configured to scan the SLO measurement light in the first direction perpendicular to the optical axis ;
14. The fundus imaging apparatus according to claim 13 , wherein said second scanning means scans said OCT measurement light and said SLO measurement light in said second direction . an OCT optical system that acquires tomographic information of an eye to be examined using OCT measurement light;
an SLO optical system that acquires fundus information of the eye to be inspected using SLO measurement light;
a common optical path composed of a reflective optical system that shares at least part of the optical path of the OCT measurement light and the optical path of the SLO measurement light;
measuring means for measuring the wavefront of the return light of the OCT measurement light branched by the branching means provided in the common optical path;
chromatic aberration correcting means provided in the optical path of the OCT measurement light branched from the common optical path and correcting chromatic aberration in the eye to be examined;
a first focusing means provided in the common optical path;
A fundus imaging method using a fundus imaging device having second focusing means provided in the optical path of the SLO measurement light branched from the common optical path,
a first step of adjusting the focus of the OCT measurement light and the SLO measurement light by the first focusing means;
and 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 an eye to be examined using OCT measurement light;
an SLO optical system that acquires fundus information of the eye to be inspected using SLO measurement light;
a common optical path composed of a reflective optical system that shares at least part of the optical path of the OCT measurement light and the optical path of the SLO measurement light;
measuring means for measuring the wavefront of the return light of the OCT measurement light branched by the branching means provided in the common optical path;
chromatic aberration correcting means provided in the optical path of the OCT measurement light branched from the common optical path and correcting chromatic aberration in the eye to be examined;
a first focusing means provided in the common optical path;
A fundus imaging method using a fundus imaging device having second focusing means provided in the optical path of the OCT measurement light branched from the common optical path,
a first step of adjusting the focus of the OCT measurement light and the SLO measurement light by the first focusing means;
and 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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