JP2019170807A - Imaging device and control method - Google Patents

Abstract

To provide a device capable of acquiring an AO-OCT image and an AO-SLO image without complicating a configuration.SOLUTION: A device comprises: a first scanning part for scanning a light in a first direction on a fundus oculi; a second scanning part for scanning a light in a second direction different from the first direction; an optical system for joining an optical path to the second scanning part to an optical path from the second scanning part without via the second scanning part; a common optical system for radiating a first measurement light obtained by branching the light from a first light source to the fundus oculi through the first scanning part and the optical system, and radiating a second measurement light from a second light source to the fundus oculi through the first and second scanning parts; a first generation part for generating a tomographic image on the basis of an interference light obtained by the interference of a return light and reference light of the first measurement light from the fundus oculi through the first scanning part and the optical system by the common optical system; and a second generation part for generating a fundus oculi image on the basis of the return light of the second measurement light from the fundus oculi through the first and second scanning parts by the common optical system, in which the first generation part generates a tomographic image on a prescribed position of the fundus oculi image generated by the second generation part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus and a control method thereof, and more particularly to an imaging apparatus that acquires a tomographic image of a fundus retina of an eye to be examined and a control method thereof.

  A tomographic imaging apparatus (OCT: Optical Coherence Tomography) that captures a tomographic image of the fundus retina of the eye to be examined by analyzing the frequency of the interference fringes obtained by causing the reflected light (sample light) from the fundus retina to interfere with the reference light A tomographic image is generated.

  In particular, in such an ophthalmic imaging apparatus, in recent years, higher resolution has been promoted by increasing the NA of an irradiation laser. However, when imaging the fundus, the image must be captured through the optical tissue of the eye such as the cornea or the crystalline lens. For this reason, as the resolution increases, the aberrations of the cornea and the crystalline lens greatly affect the image quality of the captured image.

  Therefore, there is a technique for imaging a fine structure by correcting the wavefront of measurement light and reflected light disturbed by the optical tissue of the eye such as the cornea and the crystalline lens of the eye to be examined using adaptive optics (AO: Adaptive Optic) technology. Are known. In OCT, OCT having a resolution capable of resolving photoreceptor cells using AO technology has been developed.

Japanese Patent Laying-Open No. 2015-221091 Japanese Patent No. 5641744

  When capturing a high-definition OCT image that can resolve a photoreceptor cell, it is more susceptible to motion artifacts due to the movement of the eye to be examined than an OCT image with a normal resolution. Also, in order to generate a tomographic image in which a plurality of B-scan images are superimposed in order to improve image quality, a plurality of B-scan images captured by scanning the same line with measurement light accurately are required. Highly accurate tracking is required.

  In this case, the same resolution as that of the AO-OCT image is also required for the motion detection image captured for tracking when capturing the AO-OCT image. Therefore, it is necessary to use an AO-SLO image captured by an AO-SLO (Scanning Laser Ophthalmoscope). However, if AO-SLO and AO-OCT are mounted on one apparatus, the entire apparatus becomes large and complicated, and a large number of expensive devices are required. Patent Document 1 and Patent Document 2 disclose devices equipped with AO-SLO and AO-OCT, but the technique of Patent Document 1 differs in the imaging range of AO-SLO images and AO-OCT images, Further, there are few optical systems that can be shared, and the above-mentioned problems have not been solved. Moreover, the apparatus of patent document 2 cannot perform the above-mentioned subject because the imaging by AO-SLO and AO-OCT is not simultaneous.

  An object of the present invention is to provide an imaging apparatus capable of simultaneously capturing an AO-OCT image and an AO-OCT image without complicating the apparatus configuration.

  It is another object of the present invention to provide an imaging apparatus capable of tracking using an AO-SLO image when an AO-OCT image is captured.

  In order to solve the above-described problem, an imaging apparatus according to the present invention includes a first scanning unit that scans light on the fundus in a first direction, and the light on the fundus that is different from the first direction. And a second scanning unit that scans in the second direction, and an optical that joins the optical path to the second scanning unit to the optical path from the second scanning unit without passing through the second scanning unit. A first measurement light that is branched from the system and the first light source is irradiated to the fundus via the first scanning means and the optical system, and the second measurement light from the second light source A common optical system that irradiates the fundus through the first scanning unit and the second scanning unit, and the common optical system from the fundus through the first scanning unit and the optical system. The return light of the first measurement light and the reference light obtained by branching the light from the first light source interfere with each other. First measurement means for generating a tomographic image of the fundus oculi based on the light, and the second measurement light from the fundus through the first scanning means and the second scanning means by the common optical system Second generating means for generating a fundus image of the fundus oculi based on the return light of the fundus, wherein the first generating means is a predetermined position of the fundus image generated by the second generating means. A tomographic image is generated.

  Moreover, the imaging device of the present invention is an imaging device that acquires an image of the fundus imaging range, and scans a predetermined position of the imaging range with a first measurement light obtained by branching light from a first light source. A first tomographic image of the fundus is generated based on the interference light generated by causing the return light of the first measurement light from the fundus to interfere with the reference light branched from the light from the first light source. And a second generation unit that generates a fundus image of the fundus based on the return light of the second measurement light from the fundus by scanning the imaging range with the second measurement light. And correction means for correcting the irradiation position of the fundus of the first measurement light and the second measurement light based on the fundus image generated by the second generation means.

  According to the present invention, it is possible to simultaneously capture an AO-OCT image and an AO-OCT image without complicating the apparatus configuration. Further, according to the present invention, tracking using an AO-SLO image can be performed when an AO-OCT image is captured.

It is a figure which shows the structure of the imaging device in one Embodiment of this invention. It is a figure which shows the display screen displayed on the monitor at the time of imaging | photography in one Embodiment of this invention. It is a figure for demonstrating the relationship between the acquisition position of the AO-OCT image and AO-SLO image in one Embodiment of this invention. It is a figure for demonstrating fundus tracking in one embodiment of the present invention. It is a figure for demonstrating the imaging range at the time of volume data acquisition in one Embodiment of this invention. It is a figure for demonstrating the imaging range at the time of volume data acquisition in one Embodiment of this invention. It is a figure for demonstrating the imaging range at the time of volume data acquisition in one Embodiment of this invention. It is a figure for demonstrating the imaging range at the time of volume data acquisition in one Embodiment of this invention. It is a figure for demonstrating the imaging range at the time of volume data acquisition in one Embodiment of this invention. It is a figure for demonstrating the drive waveform of the scanner at the time of the imaging in one Embodiment of this invention. It is a figure for demonstrating the drive waveform of the Y scanner at the time of tracking of one Embodiment of this invention. It is a figure for demonstrating the drive waveform of the X scanner at the time of tracking of one Embodiment of this invention. It is a figure for demonstrating the structure of the X direction scanning part in one Embodiment of this invention. It is a flowchart at the time of the imaging in one Embodiment of this invention. It is a flowchart at the time of tracking in one Embodiment of this invention.

  An embodiment of the present invention will be described in detail below with reference to the drawings. The following description is merely illustrative and exemplary in nature and is not intended to limit the present disclosure and its application or uses in any way. Relative configurations of components shown in the embodiments, as well as steps, numerical representations and numerical values do not limit the scope of the present disclosure unless otherwise specified. Techniques, methods and devices well known by those skilled in the art may not have been discussed in detail because those skilled in the art do not need to know these details to enable the embodiments discussed below.

[First Embodiment]
What can be imaged by the apparatus of this embodiment is, for example, a tomographic image of the retina of the fundus of the eye to be examined.

(Device configuration)
An example in which the Fourier domain optical coherence tomography according to the present embodiment is applied to a fundus tomographic imaging apparatus will be described with reference to the imaging apparatus shown in FIG.

  FIG. 1 illustrates an imaging apparatus according to the present embodiment, which includes an AO-OCT unit, an AO-SLO unit, an anterior ocular segment observation unit, and a fixation lamp unit. A sample optical system that is a common optical system for the AO-OCT section and the AO-SLO section is also included.

  The light source 1 of AO-OCT is a light source that generates low coherence light as AO-OCT measurement light. In the present embodiment, an SLD (Super Luminescent Diode) light source having a center wavelength of 855 nm and a wavelength width of 100 nm is used as the light source 1.

  The light emitted from the light source 1 is branched to the sample optical system 101 and the reference optical system 102 by the fiber coupler 2, and the light branched to the sample optical system 101 side is supplied to the sample optical system 101 via the adapter 3 and the fiber 4. Led. The sample optical system 101 includes a collimator lens 5, a BS (beam splitter) 6 that is a wavelength separation mirror that branches off from the AO-SLO optical system, and a BS (beam splitter) 7 that is a half mirror that branches an optical path to the wavefront detection optical system 105. , Mirror 8, concave mirror 9, variable shape mirror, DM (Deformable Mirror) 10, which is a wavefront correction measure used for wavefront correction, concave mirror 11, a wavelength branching mirror that branches and merges OCT measurement light and SLO measurement light BS (beam splitter) 12, fixed mirror 13, concave mirror 14, galvano mirror scanning in X direction, X scanner 15 such as MEMS mirror, concave mirror 16, mirrors 17a and 17b, mirror 19, lens 20, and scanning in Y direction An anterior ocular segment observation optical system 1 including a Y scanner 21, a concave mirror 22, and a wavelength selection mirror 6, constituted by BS (beam splitter) 23 for branching the fixation lamp optical system 107. The mirrors 17a and 17b are integrated and configured to be movable in the optical axis direction by the stage 18, and perform focus adjustment of the sample optical system.

  The light source 24 is a light source such as an LD (Laser Diode) light source, an SLD light source, or an LED (Light Emitting Diode) light source that emits AO-SLO measurement light, and has a wavelength different from that of the AO-OCT measurement light. In this embodiment, an SLD light source having a center wavelength of 760 nm and a wavelength width of 10 nm is used. The light emitted from the light source 24 is guided to the fiber 26 through the fiber adapter 25 and is guided to the AO-SLO projection optical system 103. The AO-SLO projection optical system 103 passes through the collimator lens 27, BS28, the focus adjustment lenses 29 and 30, the mirror 31, and the BS6, and merges with the AO-OCT optical path of the sample optical system 101 via the above-described path. To BS12.

  The BS 28 is a half mirror that transmits 10% light and reflects 90% light in order to branch the optical paths of the AO-SLO projection optical system and the AO-SLO light receiving optical system. BS6 is a wavelength branching mirror that transmits AO-SLO measurement light and reflects AO-OCT measurement light.

  As will be described later, the BS 12 is a wavelength branching mirror that reflects AO-OCT measurement light and transmits AO-SLO measurement light, and transmits AO-SLO measurement light and reflects it by a high-speed scanner 32 that is a high-speed scanner. The light is again merged with the AO-OCT measurement light by the BS 12. Thereafter, the AO-OCT sample optical system and the BS (beam splitter) 23 constitute the AO-SLO projection optical system. The AO-SLO light receiving optical system 104 is arranged in the reflection direction of the BS 28 and includes a light receiving element 35 including a lens 33, a confocal stop 34, and an APD (Avalanche photo Diode). The light receiving element 35 receives the return light from the fundus via the confocal stop 34.

  As the high-speed scanner 32, a resonance scanner or a MEMS (Micro Electro Mechanical System) scanner that can perform reciprocal scanning at about 8 kHz to 16 kHz can be used. However, these high-speed scanners can adjust the swing angle, but cannot change the center angle of scanning. Therefore, a separate scanner needs to be prepared for tracking or moving the imaging range.

  Further, the irradiation position of the AO-OCT measurement light imaged on the fundus is substantially the same as the irradiation position of the AO-SLO measurement light imaged on the fundus when the swing angle is 0. It has been adjusted.

  The reference optical system 102 includes a collimator lens 36, a density variable filter 37, mirrors 38, 39, 40, and 41, a CQ 42 that is a corner cube mirror, and a mirror 43. The CQ 42 is composed of three surfaces whose reflecting surfaces are orthogonal to each other, is disposed on the stage 44, and is movable about ± 100 mm. This corresponds to the difference in the optical axis length due to the focus adjustment of the AO-OCT measurement light caused by the difference in the axial length of the eye to be examined and the movement of the stage 18 of the sample optical system.

  In the optical system of the spectroscope 108, interference light is imaged on the line sensor 49 by a collimator lens 46, a spectral member 47 such as a grating, and an imaging lens 48.

  The wavefront detection optical system 105 includes a mirror 55, a lens 56, a fundus conjugate diaphragm 57, a lens 58, a filter 60 that can be inserted and removed, and a wavefront sensor 61 such as a Hartmann Shack sensor that is wavefront detection means. The diaphragm 57 prevents unnecessary light other than the return light from the fundus from entering the wavefront sensor 61.

  The anterior ocular segment observation optical system 106 includes a camera 51 and captures an anterior ocular segment image illuminated by the anterior ocular segment illumination light source 52.

  The fixation lamp projection optical system 107 includes a fixation lamp presentation unit 54 such as an organic EL or a liquid crystal display device. By displaying an index on the fixation lamp presentation unit 54, the lens 53 and a wavelength branch that transmits visible light are displayed. A fixation target is presented to the eye to be examined via the mirrors BS50 and BS23.

  Reference numeral 62 denotes a PC which controls the above-described units as will be described later.

(X direction scanning part)
FIG. 13 shows the configuration of the X-direction scanning unit. The same components as those in FIG. The BS 12 is a wavelength branching mirror, which reflects AO-OCT measurement light having a wavelength of 805 nm to 905 nm and transmits AO-SLO measurement light having a wavelength of 750 nm to 770 nm. This transmission characteristic can be obtained by vacuum-depositing a plurality of types of dielectric multilayer films having different refractive indexes by about 30 to 70 layers by a known method. This multilayer film is applied to the surface on the incident side.

  The AO-OCT measurement light that reaches the multilayer film in the region 141 on the surface 12a of the BS 12 is reflected upward in FIG. A known antireflection film is deposited on the surface 13a of the mirror 13, and the reflectance is 0.3% or less. Accordingly, the AO-OCT measurement light is refracted by the front surface 13a, enters the substrate, and reaches the back surface 13b. The mirror 13 substrate is made of quartz glass, optical glass BK7, or the like, and has a refractive index of about 1.5. A metal film such as silver, gold, and aluminum is deposited on the back surface 13b.

  The AO-OCT measurement light is reflected by this film, passes through the substrate again, exits from the mirror surface 13a into the air, reaches the multilayer film in the region 142 of the surface 12a of the BS 12, and is reflected and merged with the AO-SLO measurement light. To do. The AO-OCT measurement light is refracted by the surface 13a of the mirror 13 and is transmitted through the substrate, thereby being affected by astigmatism.

  The AO-SLO measurement light is transmitted through and refracted through the multilayer film in the region 141 of the surface 12a and enters the BS 12 substrate. This substrate is also quartz glass, optical glass BK7, and the like, similar to the mirror 13. And it is refracted again from the back surface 12b and comes out in the air. A known antireflection film is applied to the back surface 12b. This antireflection film has a reflectivity of AO-SLO measurement light and AO-OCT measurement light of 0.3% or less. Thereby, generation | occurrence | production of a ghost and flare can be reduced.

  Further, the transmitted light is affected by astigmatism by being obliquely transmitted through the BS 12 which is also a parallel plate. The AO-SLO measurement light emitted into the air is reflected by the mirror of the movable part of the high-speed scanner 32 and scanned in different directions depending on the angle of the mirror of the movable part. The mirror of the movable part of the high-speed scanner 32 is a plane mirror, and a metal film such as silver, copper, or aluminum is applied on the surface, and a protective film of a dielectric multilayer film is applied thereon. The AO-SLO measurement light is reflected by this metal film surface. Then, the light is refracted again by the antireflection surface 12b of the region 142 of the BS 12, passes through the substrate, and travels out of the multilayer film on the surface 12a into the air. In this way, since the light passes through the BS 12 twice, it is affected by astigmatism for two times. The traveling direction of the return light from the fundus is also opposite or affected by the same aberration.

  At this time, the substrate thicknesses of the BS 12 and the mirror 13 are equal, and the refractive indexes of the substrates are made equal by using the same glass material. With such a configuration, the astigmatism of the AO-OCT measurement light and the AO-SLO measurement light becomes substantially equal, and high-precision aberration correction can be performed under the same wavefront correction conditions using a common DM. .

  The incident light paths of the AO-OCT measurement light and the AO-SLO measurement light to the X-direction scanning unit are the return light of the AO-OCT measurement light and the output light of the return light of the AO-SLO measurement light from the X-direction scanning unit. It becomes a road. Further, the outgoing optical paths of the AO-OCT measurement light and the AO-SLO measurement light from the X direction scanning unit are incident on the return light of the AO-OCT measurement light and the return light of the AO-SLO measurement light to the X direction scanning unit. It becomes an optical path.

  Further, with respect to the AO-OCT measurement light and the AO-SLO measurement light, the DM 10, the wavefront sensor 61, the X scanner 15, the Y scanner 21, and the pupil of the eye to be examined are conjugated, and the projection position of the fundus coincides with the high speed. The intervals and angles of the scanner 32, BS12, and mirror 13 are adjusted. Thereby, the aberration of the AO-OCT measurement light and the AO-SLO measurement light can be corrected satisfactorily with one DM10.

  With the above configuration, a frontal image of the fundus centered on the imaging range of the AO-OCT image can be obtained without affecting the luminous flux of the AO-OCT measurement light. Therefore, accurate tracking using this image is possible. It can be performed.

(Imaging method)
Next, a method of acquiring and acquiring an AO-OCT image for scanning the same region of the fundus Er of the eye E to be examined a plurality of times and creating a superimposed image using the apparatus having the above-described configuration is illustrated in FIG. 2 and FIG. FIG. 2 is a diagram showing a display screen displayed on the monitor of the PC 62 during imaging, and FIG. 14 is a flowchart during imaging.

  The eye E to be examined is placed in front of this apparatus. The reflected light from the anterior segment of the subject's eye illuminated by the anterior segment illumination light source 52 is reflected by the BS 50, captured by the anterior segment observation camera 51, and displayed in the anterior segment image display area 80 of the monitor 70 of the PC 62. Is displayed. The imager looks at the anterior segment image and uses an alignment mechanism (not shown) to optically position the pupil image of the subject's eye at the center of the display area 80 so that the iris pattern can be clearly seen. The system is aligned with the pupil of the eye to be examined (step S151).

  When the alignment is completed, the photographer operates the AO-SLO image capturing start switch 71 on the monitor. Upon detecting this switch input, the PC 62 turns on the AO-SLO light source 24, drives the high-speed scanner 32 and the Y scanner 21, and starts a raster scan of the fundus using the AO-SLO measurement light (step S152).

  The reflected and scattered light from the fundus Er illuminated in this way returns to the AO-SLO sample optical system, and 10% of the light passes through the BS 7 and reaches the wavefront sensor 61 via the fundus conjugate diaphragm 57. 90% of the light reflected by BS7 is transmitted through BS6, 80% of the light is reflected by BS28, condensed by the lens 33 onto the confocal stop 34, and the light passing through the confocal stop 34 is APD, The light reaches the light receiving element 35 such as PMT. Based on a voltage signal corresponding to the amount of light received by the light receiving element 35, the PC 62 generates image data and displays it as a front image of the fundus in the AO-SLO image display area 81 on the monitor 70.

  The photographer performs focus adjustment by operating the focus switch 72 while viewing this image. The PC 62 that has detected the input to the focus switch 72 controls the drive unit of the stage 18 in order to move the mirrors 17a and 17b together in the optical axis direction. As a result, the fundus conjugate position in the optical system changes and the focus can be adjusted to a desired depth position (step S153). This is called a Badal optical system, and the imaging relationship of the pupil is maintained. As a result, an AO-SLO image having a desired depth is displayed in the display area 81.

  Further, the imager operates the fixation lamp operation switch 73 to guide fixation of the eye to be inspected so that a fundus image of a desired region is captured (step S154).

(Aberration correction)
When the PC 62 detects that an AO-SLO image having a signal intensity of a certain level or more is stably obtained, an aberration correction (AO) operation is started. Part of the reflected light from the fundus passes through the BS 7 and reaches the wavefront sensor 61, and output data of the wavefront sensor 61 is sent to the PC 62. Since the wavefront sensor 61 has a lens array disposed in front of the light receiving element, the output image is an image in which spots are arranged in a grid pattern (grid shape). If there is aberration in the eye to be examined, these spot positions change. The wavefront aberration is obtained by analyzing the deviation direction and the amount of deviation of each spot (step S155).

  In order to correct the wavefront aberration, the PC 62 obtains a pattern for displacing the micromirrors that constitute the DM 10 that is an aberration correction device. The PC 62 corrects the aberration by controlling the driving of the micro mirror of the DM 10 according to this pattern (step S156).

  By correcting the aberration of the AO-SLO measurement light, the spot diameter projected onto the fundus is reduced, and at the same time, the spot diameter formed on the confocal stop is also reduced, so that the amount of light received by the light receiving element 35 increases. Thereby, a high-resolution photoreceptor cell image is clearly displayed in the display area 81 of the AO-SLO image on the monitor 70 of the PC 62. Note that a line 81a indicates the imaging position of the AO-OCT image.

(AO-OCT imaging)
Next, the photographer operates the switch 74 to instruct the start of imaging of the AO-OCT image (step S157). The PC 62 that has detected the input to the switch 74 turns on the AO-OCT light source 1. As a result, the AO-OCT measurement light branched to the sample optical system side by the coupler 2 enters the sample optical system from the fiber 4. The AO-OCT measurement light entering the sample optical system is collimated by the collimator lens 5 and reaches the BS 12. As described above, the AO-OCT measurement light is reflected by the BS 12, further reflected by the fixed mirror 13, and again reflected by the BS 12, thereby joining the optical path of the AO-SLO measurement light. Thereby, the AO-OCT measurement light reaches the eye to be examined without being affected by the high-speed scanner 32. The reflected light reflected by the fundus of the AO-OCT measurement light travels back through the sample optical system, is reflected by the BS 12, is reflected by the mirror 13, is reflected by the BS 12, and reaches the half mirror BS7. BS7 has a transmission characteristic of reflecting 90% light and transmitting 10% light. 10% of the reflected light from the BS 7 is transmitted to the wavefront sensor 61, and the remaining 90% of the reflected light is reflected by the BS 7 and BS 6, and is imaged on the end face of the fiber 4 by the collimator lens 5. As a result, the fiber coupler 2 is reached.

(AO-OCT wavefront detection)
When imaging of an AO-OCT image is started, a filter 60 that cuts AO-SLO measurement light is inserted in front of the wavefront sensor 61. Therefore, the light reaching the wavefront sensor 61 is only the AO-OCT measurement light, and the light whose wavefront is detected is switched from the AO-SLO measurement light to the AO-OCT measurement light, and the wavefront aberration of the AO-OCT measurement light is detected. (Step S158). However, the AO-SLO projection optical system includes focus adjustment lenses 29 and 30, and the focus adjustment lenses 29 and 30 are different in focus positions due to differences in wavelengths of the AO-SLO measurement light and the AO-OCT measurement light. Is automatically corrected. Based on the detected wavefront aberration, the driving amount of each mirror of DM10 is calculated as described above, and the wavefront aberration is corrected by driving DM10 (step S159). Thereby, the AO-OCT image displayed in the display area 82 is brighter and the contrast is improved.

(Reference optical system)
The reference light branched to the reference optical system side by the fiber coupler 2 is polarized by the polarization adjuster 45 so that the polarization state matches the return light of the sample optical system, enters the reference optical system 102, and is used for adjusting the reference light amount. An appropriate light amount is adjusted by an ND (Neutral Density) filter 37. The reference light reflected by the mirrors 38, 39, 40 and 41 and reflected by the retro reflector 42 is reflected by the mirrors 41, 40, 39 and 38 and reaches the mirror 43. The light vertically reflected by the mirror 43 travels back along the optical path and returns to the coupler 2.

  The reference light from the reference optical system 102 and the return light from the fundus of the eye of the sample optical system are combined (combined) by the coupler 2 and guided to the spectroscope 108 as interference light. The interference light guided to the spectroscope 108 is collimated by the lens 46, is split by the spectroscopic means 47 such as a diffraction grating, and an interference wave is imaged on the line sensor 49 by the lens 48. The output of the line sensor 49 is sent to the PC 62, converted into digital data by the A / D converter 62a, and stored in the memory 62b. This data is computed by a known method such as frequency analysis after removal of fixed pattern noise and wave number conversion to generate tomographic image data.

(Gate adjustment)
The imager adjusts the optical path length of the reference optical system 102 using the optical path length adjustment switch 76 shown in FIG. 2 so that a desired tomographic image is displayed in the display area. The PC 62 that has detected the input to the optical path length adjustment switch 76 drives the stage 44 in a direction corresponding to the input. Thereby, the retro reflector 42 moves in the optical axis direction, and the optical path length changes. When the optical path length of the sample system and the optical path length of the reference system substantially coincide with each other, a tomographic image of a photoreceptor cell is displayed in the display area 82 (step S160).

(scan)
At this time, an AO-SLO image captured at the same time is displayed in the display area 81. Since the high-speed scanner 32 is arranged around the OCT optical system, the AO-OCT measurement light is only line-scanned by the Y scanner 21 in the Y direction (horizontal direction in FIG. 3). The AO-SLO measurement light is scanned in the Y direction by the Y scanner 21 and in the X direction (the vertical direction in FIG. 3) by the high speed scanner 32. Therefore, as shown in FIG. 3, an AO-SLO image of the imaging range 301 with the scanning line 302 that is the acquisition position of the AO-OCT image as the center in the vertical direction is acquired (step S161).

  A waveform 111 shown in FIG. 10 represents the scanning angle of the mirror of the high-speed scanner 32, the horizontal axis is time, and the vertical axis is the angle. That is, the high-speed scanner 32 reciprocates at high speed in the X direction. At the same time, the Y scanner 21 is scanned at a cycle slower than that of the waveform 111 as indicated by the waveform 112. Image acquisition is performed for both the forward and backward passes of the high-speed scanner.

  A period P1 shown in FIG. 10 is a period for acquiring an image of one frame for an AO-OCT image and a frame for an AO-SLO image. P2 is a blanking period for the Y scanner 21, and no image acquisition is performed. . That is, the Y scanner 21 continuously changes from θ2 to −θ2 in the period P1, and is scanned from the angle P2 to + θ2 in the period P2 at an angular velocity faster than the angular velocity in the period P1. By repeating such scanning, a two-dimensional region is imaged by the AO-SLO unit and a line is imaged by the AO-OCT unit.

(tracking)
Tracking of movement of the eye to be examined and correction of the imaging range will be described with reference to the flowchart of FIG.

  When the imaging of the AO-OCT image is started, an AO-SLO image is recorded as one frame as a tracking reference image 301 (step S1621). The image size at this time is 400 × 400 pixels, and the image is composed of 400 lines in length. When the scanning frequency of the high-speed scanner 32 is 16 kHz, an image is acquired in a reciprocating manner. Therefore, it takes 12.5 msec to acquire an image of 400 lines, and an image of about 70 frames per second is obtained. As shown in FIG. 4, at the time of imaging the next frame, every time an image of a predetermined line is acquired, a correlation calculation is performed with the reference image to detect the movement of the eye to be examined. For example, in the present embodiment, the tracking image 402 is created with signals for 20 lines (step S1622). This makes it possible to detect the position 20 times (= 400/20) during one line scanning of the AO-OCT image. That is, the movement of the eye to be examined can be detected and corrected in a time of 1 msec or less. For this reason, it is possible to track fixation fine movement that moves at a speed of about 1 mm per second with an accuracy of 1 μm or less, and to obtain sufficient accuracy for an OCT line scan with a line width of 3 μm. As soon as each tracking image is acquired, a correlation operation is performed with the reference image 301 to obtain a shift amount (sf302_X, SF302_Y) (step S1623). If there is no movement of the eye to be examined, the shift amount of the Nth tracking image is (x, y) = (20 × (n−1), 0), and therefore the movement of the eye to be examined obtained from the Nth tracking image. The amount is (sf302_x-20N, SF302_y) (S1623).

  Based on this movement amount, the mirror rotation angle of the X scanner 15 and Y scanner 21 is calculated (step S1631), and the X scanner 15 and Y scanner 21 are driven so as to follow the movement of the eye to be examined as described above. Since the Y scanner 21 is being driven with a predetermined waveform, the drive center is offset. The X scanner 15 performs only the obtained amount of offset (step S1632).

  A waveform 121 in FIG. 11 shows a change in angle of the Y scanner 21, and a waveform 131 in FIG. 12 shows a change in angle of the X scanner 15. The horizontal axis is the time vertical axis, and the vertical axis is the scanning angle. As described above, since the angle shift amount for correcting the movement amount of the eye to be examined is calculated at regular time intervals, the scan angle is shifted as indicated by the waveform 122. Thereafter, scanning is performed at a normal angular velocity as indicated by a waveform 123. A solid line indicates a mirror angle to which an angle shift is applied, and a broken line indicates a mirror angle when there is no angle shift. A waveform 131 in FIG. 12 shows an angle change of the X scanner 15, and the horizontal axis is time. Since the X scanner 15 is used only for tracking for correcting the movement of the eye to be examined, the angle changes only by the calculated offset amount.

  Although the AO-SLO image is acquired even while the X scanner 15 is driven as shown by the waveform 132, the correlation calculation is performed on the image excluding the portion. By continuing such tracking control, the AO-OCT unit can obtain a plurality of tomographic images on the same line, a predetermined number, for example, about 100 (step S1633). These tomographic images are strictly the same region, and an AO-OCT image with high contrast can be created by superimposing these images.

(OCT volume scan)
When the AO-OCT volume scan switch 75 is operated, scanning in the volume scan mode is started.

  When the photographer operates the AO-OCT volume scan switch 75 and an imaging range is set using a cursor (not shown), the PC 62 synchronizes with the X scanner 15 so that the OCT line scan line is shifted in the Y direction. The Y scanner 21 is also driven.

  A frame 501 on the fundus image in FIG. 5 indicates an imaging range of the AO-OCT volume scan. A region corresponding to the frame 501 on the fundus image is scanned with AO-OCT measurement light to acquire AO-OCT volume data. A frame 601 in FIG. 6 shows the imaging range of the AO-SLO image when the uppermost line 502 of the imaging range in FIG. 5 is scanned with the AO-OCT measurement light. As shown in FIG. 5, the imaging range of the AO-SLO image is a rectangular area centered on the imaging line 502 of the AO-OCT image. The AO-SLO image obtained here is stored as a tracking reference image. Next, the X scanner 15 is driven, and the AO-OCT measurement light starts scanning the next imaging line indicated by the line 503 in FIG. The imaging range of the AO-SLO image at that time is shown in a frame 701 in FIG. With respect to the imaging range 601, the imaging range of the AO-SLO image moves downward by one line of the AO-OCT image. That is, when an AO-OCT image is captured on the line 504 in FIG. 5, the AO-SLO image is the imaging range shown in the frame 801 in FIG. 8, and the line 505 that is the lowest line is captured. In FIG. 9, a frame 901 is an imaging range of the AO-SLO image. Thus, the imaging range of the AO-SLO image moves with the movement of the scan line of the AO-OCT measurement light. As a result, image information in the vicinity region centered on the imaging range of the AO-OCT image is always obtained.

(tracking)
As described above, tracking is performed using an AO-SLO image even during AO-OCT volume scanning. While scanning the line 503 in FIG. 7, an image of the 20-line range indicated by the broken line is extracted while acquiring the image of the imaging range 701 of the AO-SLO image, and the image of the imaging range 601 of the AO-SLO image captured last time To calculate the shift amount. As described above, the shift amounts of the X scan 15 and the Y scanner 16 are calculated from this shift amount, and the X scanner 15 and Y scanner 21 are immediately driven on the fundus of the AO-OCT measurement light and the AO-SLO measurement light. Fundus tracking is performed to correct the irradiation position.

  The AO-OCT image (volume data) in the imaging range 501 of the AO-OCT image is acquired by repeating the line scan while performing tracking in this way. Thereby, the three-dimensional information of the area 501 in FIG. 5 is obtained.

  The AO-SLO image used for tracking is preferably used as a reference image at the time of line scanning of the AO-OCT image in the next row after each shift amount is corrected to create one reference image. As a result, the reference image can be constantly updated, so that more accurate tracking can be performed.

[Second Embodiment]
In the first embodiment, the configuration in which an AO-OCT image at a predetermined position (center position in the X direction) in the imaging range of the AO-SLO image has been described. In the present embodiment, a case where the fixed mirror 13 shown in FIG. 13 is replaced with a galvanometer mirror will be described.

  The angle of this galvanometer mirror is changed by an angle corresponding to one line (in the X direction) every time one AO-SLO image (one frame) is acquired. Thereby, AO-OCT volume data of the imaging range can be acquired. Since the range for acquiring the AO-SLO image does not change, it is not necessary to consider the shift amount at the time of frame acquisition at the time of tracking.

[Other Embodiments]
In the above-described embodiment, the case where the object to be inspected is an eye is described. However, the present invention can also be applied to an object to be inspected other than the eye, such as skin or organ. In this case, the present invention has an aspect as a medical device such as an endoscope other than the imaging device. Therefore, it is preferable that the present invention is grasped as an image processing apparatus exemplified by the imaging apparatus, and the eye to be examined is grasped as one aspect of the inspection object.

  The present invention can also be achieved by configuring the apparatus as follows. That is, a recording medium (or storage medium) that records software program codes (computer programs) that implement the functions of the above-described embodiments may be supplied to the system or apparatus. In addition to the form of the recording medium, a computer-readable recording medium may be used. Then, the computer (or CPU or MPU) of the system or apparatus reads and executes the program code stored in the recording medium. In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiment, and the recording medium on which the program code is recorded constitutes the present invention. The embodiment can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Claims (12)

First scanning means for scanning light on the fundus in a first direction;
Second scanning means for scanning the light on the fundus in a second direction that is different from the first direction;
An optical system for merging the optical path to the second scanning unit with the optical path from the second scanning unit without passing through the second scanning unit;
The first measurement light branched from the light from the first light source is irradiated to the fundus through the first scanning means and the optical system, and the second measurement light from the second light source is irradiated to the first light. A common optical system for irradiating the fundus through one scanning means and the second scanning means;
The common optical system causes the return light of the first measurement light from the fundus through the first scanning means and the optical system to interfere with the reference light that is branched from the light from the first light source. First generating means for generating a tomographic image of the fundus oculi based on interference light caused by
Second generation means for generating a fundus image of the fundus based on the return light of the second measurement light from the fundus via the first scanning means and the second scanning means by the common optical system. And
The imaging apparatus, wherein the first generation unit generates a tomographic image at a predetermined position of the fundus image generated by the second generation unit. The common optical system includes a wavefront sensor that measures wavefront aberration, and a wavefront correction device that corrects wavefront aberration,
The wavefront sensor measures the wavefront aberration of the return light of the first measurement light from the fundus or the wavefront aberration of the return light of the second measurement light from the fundus;
The wavefront correction device corrects the wavefront of the return light of the first measurement light from the fundus and the wavefront of the return light of the second measurement light from the fundus. The imaging device described in 1. Detecting means for detecting movement of the fundus;
The third scanning means provided in the common optical system further changes irradiation positions of the first measurement light and the second measurement light in order to correct the movement. The imaging apparatus according to 1 or 2. The optical system is
Separating means arranged in an optical path to the second scanning means and separating the first measurement light;
Reflecting means for reflecting the first measurement light separated by the separating means;
The first measuring light reflected by the reflecting means has a joining means for joining the optical path from the second scanning means;
The first measurement light is applied to the fundus by the separation unit and the merging unit via the first scanning unit without passing through the second scanning unit. 4. The imaging device according to any one of 3.   The imaging apparatus according to claim 4, wherein the separating unit includes a beam splitter, and the joining unit includes a mirror.   The imaging apparatus according to claim 1, wherein the second scanning unit is driven at a faster frequency than the first scanning unit. An imaging device that acquires an image of a fundus imaging range,
The return light of the first measurement light from the fundus by scanning the predetermined position of the imaging range with the first measurement light branched from the light from the first light source, and from the first light source First generation means for generating a tomographic image of the fundus based on interference light by causing interference with reference light branched from light;
Second generation means for generating a fundus image of the fundus based on a return light of the second measurement light from the fundus by scanning the imaging range with a second measurement light;
An imaging device comprising: correction means for correcting an irradiation position of the fundus of the first measurement light and the second measurement light based on the fundus image generated by the second generation unit. apparatus. First scanning means for scanning the imaging range in the first direction with the first and second measurement lights;
Second scanning means for scanning the imaging range with the second measurement light in a second direction that is different from the first direction;
The first measurement light is applied to the fundus via the first scanning means and not the second scanning means, and the second measurement light is applied to the first scanning means and the second scanning light. The imaging apparatus according to claim 7, further comprising: a common optical system that irradiates the fundus through a scanning unit. The common optical system includes a wavefront sensor that measures wavefront aberration, and a wavefront correction device that corrects wavefront aberration,
The wavefront sensor measures the wavefront aberration of the return light of the first measurement light from the fundus or the wavefront aberration of the return light of the second measurement light from the fundus;
The wavefront correction device corrects the wavefront of the return light of the first measurement light from the fundus and the wavefront of the return light of the second measurement light from the fundus. Or the imaging device of 8. The common optical system is:
Separating means arranged in an optical path to the second scanning means and separating the first measurement light;
Reflecting means for reflecting the first measurement light separated by the separating means;
The first measuring light reflected by the reflecting means has a joining means for joining the optical path from the second scanning means;
The first measurement light is irradiated to the fundus by the separation unit and the merging unit via the first scanning unit without passing through the second scanning unit. The imaging apparatus according to any one of 9. First scanning means for scanning light on the fundus in a first direction;
Second scanning means for scanning the light on the fundus in a second direction that is different from the first direction;
An optical system for merging the optical path to the second scanning unit with the optical path from the second scanning unit without passing through the second scanning unit;
The first measurement light branched from the light from the first light source is irradiated to the fundus through the first scanning means and the optical system, and the second measurement light from the second light source is irradiated to the first light. A common optical system for irradiating the fundus through one scanning means and the second scanning means;
The common optical system causes the return light of the first measurement light from the fundus through the first scanning means and the optical system to interfere with the reference light that is branched from the light from the first light source. First generating means for generating a tomographic image of the fundus oculi based on interference light caused by
Second generation means for generating a fundus image of the fundus based on the return light of the second measurement light from the fundus via the first scanning means and the second scanning means by the common optical system. A method of controlling an imaging apparatus comprising:
The imaging apparatus control method, wherein the first generation unit generates a tomographic image at a predetermined position of the fundus image generated by the second generation unit. A method for controlling an imaging apparatus that acquires an image of an imaging range of a fundus,
The return light of the first measurement light from the fundus by scanning the predetermined position of the imaging range with the first measurement light branched from the light from the first light source, and from the first light source A first generation step of generating a tomographic image of the fundus based on interference light by causing interference with reference light branched from light;
A second generation step of generating a fundus image of the fundus based on the return light of the second measurement light from the fundus by scanning the imaging range with a second measurement light;
An imaging method comprising: a correction step of correcting an irradiation position of the fundus of the first measurement light and the second measurement light based on the fundus image generated in the second generation step. Control method of the device.

Images