JP2018121888A - Optical coherence tomograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical coherence tomograph favorably acquiring data on the basis of scanning of measuring light using a galvanometer mirror.SOLUTION: A coherence optical system 100 applies measuring light from a light source 102 to a tissue of a subject's eye and causes a detector 120 to detect coherence of reference light and the measuring light reflected by the tissue. A scanning section 108 includes one or more galvanometer mirrors as a main scanning optical scanner, and a sub scanning optical scanner, and two-dimensionally scans the measuring light on the subject's eye on the basis of operations of the main scanning optical scanner and the sub scanning optical scanner. A control section 70 acquires A scan data based on an output signal from the detector 120 with a period of at least 300 kHz or more. Further, the control section controls at least the galvanometer mirror to repeatedly reciprocate at a constant swing angle so as to continuously scan the measuring light in the main scanning direction twice or more such that a time difference in start timing of each time of scanning becomes a value of 5 msec or less.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an optical coherence tomometer that acquires OCT data of an eye to be examined based on the principle of optical interference.

  An optical coherence tomography (OCT) is used in the ophthalmology field in order to acquire information on the eye to be examined in the depth direction. As an optical coherence tomometer, an apparatus capable of two-dimensionally scanning measurement light on a tissue of an eye to be examined by driving an optical scanner has been known (for example, see Patent Document 1).

  In addition, the galvanometer mirror is characterized by high controllability and a high degree of freedom in scan pattern, and is therefore used as a typical optical scanner in an optical coherence tomography.

JP-A-2006-13210

  However, in the conventional optical coherence tomography, even if the galvanometer mirror is used for main scanning, the galvanometer mirror is operated in the range of about 100 hertz at most. Has not been fully examined.

  This indication is made in view of the above-mentioned situation, and makes it a technical subject to provide an optical coherence tomometer which can acquire OCT data satisfactorily based on scanning of measurement light using a galvanometer mirror.

  The optical coherence tomograph according to the first aspect of the present disclosure irradiates the tissue of the eye to be measured with the measurement light from the light source, and detects the interference between the reference light and the measurement light reflected by the tissue with a detector An OCT optical system, and one or more galvanometer mirrors that scan the measurement light in a predetermined main scanning direction on the eye by performing reciprocal driving including forward movement and backward movement, as a main scanning optical scanner And a sub-scanning optical scanner having a scanning direction different from that of the main-scanning optical scanner, and the measurement light is supplied to the eye to be inspected based on operations of the main-scanning optical scanner and the sub-scanning optical scanner. A scanning unit for two-dimensionally scanning, and control means for acquiring A scan data based on a signal output from the detector at a period of at least 300 kilohertz or more, the control means comprising: The galvo mirror By repeatedly reciprocating with a fixed swing angle, the measurement light scan is continuously executed twice or more in the main scanning direction, and the time difference at the start timing of each scan becomes a value of 5 milliseconds or less. Control at least the galvanometer mirror.

  According to the present disclosure, OCT data can be favorably acquired based on scanning of measurement light using.

It is a block diagram which shows schematic structure of the optical coherence tomography which concerns on embodiment. It is a figure for demonstrating the raster scan with respect to a fundus. It is a schematic diagram which shows a three-dimensional image. It is a schematic diagram which shows the front image based on three-dimensional OCT data. It is a schematic diagram which shows the example of a display in a monitor. It is a schematic diagram which shows another example of a display. It is a figure for demonstrating the example of the 2nd raster scan. It is a figure which shows the principal part of the optical system which concerns on a 1st modification. It is a timing chart which showed operation of each part in the 1st modification. It is a figure which shows the principal part of the optical system which concerns on a 2nd modification. It is a figure which shows the principal part of the optical system which concerns on a 3rd modification.

  Hereinafter, exemplary embodiments according to the present disclosure will be described based on the drawings. FIG. 1 shows a schematic configuration of an optical coherence tomography 1 (hereinafter referred to as “OCT1”) of the present embodiment. In the present embodiment, the OCT 1 performs an A scan with a period of 300 kilohertz or more.

  In this embodiment, OCT1 may be FD-OCT (Fourier domain OCT). Below, OCT1 demonstrates as what is SS-OCT (Swept source OCT) which is 1 type of FD-OCT. In this case, the OCT 1 has a wavelength swept light source that temporally sweeps the emission wavelength as a light source, and has a point detector as a detector. The point detector may be a single detector or a balanced detector that performs balanced detection using a plurality of (for example, two) detectors. The OCT 1 samples the interference signal of the reference light and the return light of the measurement light according to the change of the emission wavelength by the wavelength swept light source, and the OCT data of the eye to be examined based on the interference signal at each wavelength obtained by the sampling. Get.

<Optical system>
As illustrated in FIG. 1, the OCT 1 includes an OCT optical system 100 and a fixation optical system 200. The fixation optical system 200 projects a fixation target on the eye to be examined.

  The OCT optical system 100 mainly includes a light source 102, an optical scanner 108, and a detector 120. Further, as illustrated in FIG. 1, the OCT 1 includes a light dividing / coupling unit (splitter / combiner) 104 and a reference optical system 110. In the example of FIG. 1, solid lines 131 to 134 that connect the portions indicate light guiding optical fibers.

  As the light source 102, a variable wavelength light source (wavelength scanning light source) that changes the emission wavelength at a high speed in time is used. For example, the light source 102 scans the wavelength with a period of 300 kHz or more. Thereby, in OCT1, A scan data (details will be described later) can be acquired at a cycle of 300 kHz or more. Here, “300 kHz or more” can include, for example, a case where A scan is performed at a cycle of 1 MHz or more. Such a light source may be, for example, a Fourier domain mode-locked (FDML) laser. The FDML laser is a kind of wavelength swept light source. For example, the FDML laser may have a structure in which a wavelength sweep filter and a dispersion compensation mechanism for suppressing the influence of dispersion characteristics are introduced into a resonator including a gain medium. Examples of the wavelength selection filter include a filter using a combination of a diffraction grating and a polygon mirror and a Fabry-Perot etalon (see, for example, Japanese Patent Application Laid-Open No. 2012-222164 by the present applicant). The light source 102 is not necessarily an FDML laser, and may be a light source that scans a wavelength with a period of 300 kilohertz or more based on a principle different from that of the FDML laser.

  As the detector 120 illustrated in FIG. 1, for example, a balanced detector including a light receiving element may be provided. The light receiving element is a point sensor having only one light receiving portion, and for example, an avalanche photodiode is used.

  The light dividing / coupling unit 104 shown in FIG. 1 serves as both the light dividing unit and the optical coupling unit. As the light splitting unit, the light splitting / coupling unit 104 splits the light emitted from the light source 102 into measurement light (measurement light) and reference light. As a result, the measurement light is guided to the fundus Er via the optical scanner 108, and the reference light is guided to the reference optical system 110 (details will be described later). The light dividing / combining unit 104 combines the measurement light reflected by the fundus Er and the reference light as an optical coupling unit. Although details will be described later, interference light acquired by combining the measurement light reflected by the fundus Er and the reference light is received by the detector (light receiving element) 120. As an example of the light dividing / coupling unit 104 as described above, a fiber coupler is used in FIG.

  In the present embodiment, a part of the light (measurement light) split by the light splitting / coupling unit 104 first enters the optical fiber 132. The measurement light incident on the optical fiber 132 is converted into a parallel beam by a collimator lens (not shown) and is incident on the optical scanner 108.

  The optical scanner 108 is used to scan the measurement light from the light source 102 on the fundus oculi Er. The optical scanner 108 scans the measurement light in the XY direction (transverse direction) on the fundus Er. In the present embodiment, the optical scanner 108 performs a raster scan of the measurement light on the fundus. In the present embodiment, the raster scan as illustrated in FIG. 2 is periodically repeated in a constant region (a position and an area are constant) of the fundus.

  The optical scanner 108 is arranged at a position substantially conjugate with the pupil. The optical scanner 108 operates based on a control signal input to the drive unit (driver) 50.

  The optical scanner 108 according to the present embodiment includes, for example, an acousto-optic device (AOM) that changes the traveling (deflection) direction of light in addition to a reflection mirror (galvano mirror, polygon mirror, resonant scanner, MEMS scanner). May be used. For example, the optical scanner 108 shown in FIG. 1 includes two scanners: an optical scanner 108a for main scanning and an optical scanner 108b for sub scanning. The two optical scanners 108a and 108b scan light in different directions. For example, the optical scanner 108a may scan light in the X direction, and the optical scanner 108b may scan light in the Y direction. In the present embodiment, the optical scanner 108a for main scanning is preferably capable of scanning with a period of at least the order of kHz, for example. In the example of FIG. 1, a resonant scanner is used as an example of the optical scanner 108a that satisfies such conditions. However, the optical scanner 108a is not limited to the resonant scanner, and other optical scanners such as a polygon mirror and an AOM may be adopted as the main scanning optical scanner 108a. On the other hand, it is preferable that the Y-scanner 108b for sub-scanning is capable of scanning with a period of at least several tens of Hz. In the example of FIG. 1, a galvanometer mirror is used as an example of the optical scanner 108b that satisfies such a condition. However, the optical scanner is not limited to the galvanometer mirror, and another optical scanner such as AOM may be employed as the sub-scanning optical scanner 108b. Note that main scanning and sub-scanning need not be performed by separate optical scanners. For example, main scanning and sub-scanning may be performed by one optical scanner. That is, a scanner that performs optical scanning with respect to two axes may be applied to the optical scanner 108.

  In the present embodiment, raster scanning of the measurement light is periodically performed in a region on the fundus (a region having a constant area) by the two scanners 108a and 108b. The measurement light deflected by the optical scanner 108 irradiates the fundus Er through the objective optical system 106.

  The backscattered light (reflected light) from the fundus Er of the measurement light is guided to the light splitting / combining unit 104 by tracing back the optical path at the time of projection. Then, it is combined with the reference light by the light dividing / combining unit 104 and interferes.

  The reference optical system 110 generates reference light that is combined with reflected light acquired by reflection of measurement light at the fundus Er. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type. The reference optical system 110 is formed by, for example, a reflection optical system (for example, a reference mirror), and reflects light from the light dividing / combining unit 104 by the reflecting optical system. Guide to detector 120. As another example, the reference optical system 110 may be formed by a transmission optical system (for example, an optical fiber), and may be guided to the detector 120 by transmitting the light from the light dividing / coupling unit 104 without returning. .

  The OCT 1 moves at least a part of the optical member arranged in the OCT optical system 2 in the optical axis direction in order to adjust the optical path length difference between the measurement light and the reference light. For example, the reference optical system 110 has a configuration that adjusts the optical path length difference between the measurement light and the reference light by moving an optical member (for example, a reference mirror) in the reference light path. For example, the reference mirror is moved in the optical axis direction by driving the drive mechanism. The configuration for changing the optical path length difference may be arranged in the measurement optical path of the measurement optical system 20. An optical member (for example, an end portion of the optical fiber) disposed in the measurement optical path is moved in the optical axis direction.

  The interference signal light obtained by combining the measurement light and the reference light is incident on the detector 120 via the light dividing / coupling unit 104 and the fiber 134. Thereby, the detector 120 detects interference signal light.

  When the emission wavelength is changed by the light source 102, the corresponding interference signal light is received by the detector 120, and as a result, received by the detector 120 as spectrum interference signal light. A spectrum interference signal (also referred to as an OCT signal) output from the detector 120 is captured by the control unit 70. Based on this spectral interference signal, a depth profile is formed.

<Control system>
Next, the control system of the OCT 1 will be described with reference to FIG. The OCT 1 mainly includes a control unit 70 and a memory (storage unit) 71 as a control system.

  The control unit 70 is realized by, for example, a CPU (Central Processing Unit) and a memory (for example, a RAM and a ROM). The control unit 70 controls the operation of each unit of the OCT 1. For example, the control unit 70 controls the optical scanner 108 so that the raster scan of the measurement light is repeatedly performed on the fundus. Further, OCT data of the eye to be examined is acquired based on a signal output from the detector 120 as a result of the raster scan (details will be described later). The OCT data here may be any of one-dimensional OCT data, two-dimensional OCT data, and three-dimensional OCT data. In the example of FIG. 1, the control unit 70 also serves as an image processing unit. For example, the control unit 70 may include an image processing IC capable of executing various processes related to OCT data.

  The memory 72 is a rewritable nonvolatile storage medium. As the memory 72, for example, any one of a hard disk, a flash memory, an external server, and a USB memory may be used. In the present embodiment, the memory 72 stores OCT data, analysis results of the OCT data, and the like.

  As illustrated in FIG. 1, the OCT 1 may include an operation unit (input interface) 74 and a monitor 75. As shown in FIG. 1, each unit is connected via a network (bus, LAN, etc.), and can transmit and receive data (for example, image data) and the like.

  The operation unit 74 receives an operation from the examiner. For example, a device such as a mouse, a trackball, or a touch panel may be used as the operation unit 74. Further, the present invention is not limited to such a contact type device, and for example, a device that inputs a non-contact operation such as a motion sensor may be applied as the operation unit 74.

  The monitor 75 displays a graphic (for example, a tomographic image) that visualizes the OCT data, layer thickness information, and the like. In the present embodiment, display control of the monitor 75 is performed by the control unit 70. That is, in the present embodiment, the control unit 70 also serves as a display control unit. The monitor 75 may be a touch panel, for example. In this case, the monitor 75 functions as a part of the operation unit 74. The monitor 75 may be a device having a two-dimensional screen. In this case, any of a stationary type, a handheld type, a wearing type (for example, a head mounted display), and the like may be used. Further, it may be a projection type device that projects an image on a screen or the like. The monitor 75 may be a three-dimensional display that displays a three-dimensional image. As an example, in the case of a projection-type device, a volume-type display in which a three-dimensional image is projected into space may be used.

<Description of operation>
The operation of the apparatus having the above configuration will be described below.

<Acquisition of 3D OCT data>
For example, the control unit 70 acquires A scan data (an example of one-dimensional OCT data) based on a signal output from the detector 120 at a period of at least 300 kilohertz. In the present embodiment, the A scan data for one cycle is information on the tissue in the depth direction (optical axis direction) at one point on the fundus. The A scan data may be a complex OCT signal obtained by Fourier transforming a signal (OCT signal) output from the detector 120. Further, it may be a depth profile obtained by further processing the complex OCT signal.

  In the present embodiment, the control unit 70 may acquire A scan data in synchronization with the wavelength change period of the light source 102. Thereby, a plurality of points of A scan data are acquired for each scan line (for each scan line) (see FIG. 2). For example, a clock signal having a period of 300 kilohertz or more is input to both the light source 102 and the control unit 70, thereby synchronizing the wavelength scanning in the light source 102 and the acquisition of A scan data by the control unit 70, It may be configured to be executed at a cycle of 300 kHz or more.

  In the present embodiment, three-dimensional OCT data is acquired by the control unit 70 based on A-scan data of a plurality of points. The three-dimensional OCT data in this embodiment is three-dimensional tissue information in the raster scan range. One unit (in other words, one frame) of three-dimensional OCT data is obtained based on at least one cycle of raster scan. For example, the three-dimensional OCT data for one frame may include a plurality of A scan data acquired by one cycle of raster scan. In the present embodiment, the control unit 70 generates three-dimensional OCT data based on a raster scan every time one period of raster scan is performed. For example, data formed by two-dimensionally arranging depth profiles (an example of A scan data) in the XY direction may be three-dimensional OCT data. Thus, in this embodiment, one unit (in other words, one frame) of three-dimensional OCT data is formed from the interference signal output from the detector 120 as a result of raster scanning for one period.

  The generation frame rate of the three-dimensional OCT data may be set as appropriate. For example, three-dimensional OCT data in the raster scan range may be generated at a frame rate of about 8 fps by performing the raster scan at a cycle of about 8 Hz. In this case, assuming that A scan data is acquired at approximately 300 kHz, one frame of three-dimensional OCT data is constructed based on A scan data obtained from a point of about 200 × 200 in the xy direction of the fundus. Is done. Further, the number of points in the depth direction in three-dimensional OCT data (that is, the number of points in one A-scan data) depends on, for example, the spectrum width of the measurement light. For example, A scan data having a number of points of about 200 points may be acquired in the depth direction.

<Display of image based on 3D OCT data>
The control unit 70 causes the monitor 75 to display a graphic obtained by visualizing the three-dimensional OCT data generated as needed. In this embodiment, every time new three-dimensional OCT data is acquired, the control unit 70 updates the graphic displayed on the monitor 75 to a graphic obtained by visualizing the new three-dimensional OCT data. That is, in the present embodiment, the monitor 75 displays a moving image showing the tissue of the eye E (for example, the three-dimensional tissue of the fundus) in real time. As a result, the dynamics of the tissue in the fundus in real time can be observed via a moving image.

  In the present disclosure, “real time” indicates that changes in the eye to be examined at each time point are reflected on the image, information, and the like substantially simultaneously.

<Three-dimensional image display processing>
Note that the graphic obtained by visualizing the three-dimensional OCT data may be, for example, a three-dimensional image as shown in FIG. The three-dimensional image may be, for example, an image in which two-dimensional reflection intensity distributions (for example, tomographic images) in each scan line are arranged in the sub-scanning direction (direction intersecting with the scan line). That is, it may be an image showing a three-dimensional reflection intensity distribution (for convenience, such an image is referred to as a three-dimensional OCT image). The three-dimensional image may be a three-dimensional motion contrast image. The motion contrast is detection information such as movement of the subject (eye to be examined) and temporal change, for example. For example, a flow image or the like is also a kind of motion contrast. The flow image is, for example, an image obtained by detecting the movement of fluid or the like. An angiographic image (OCT angiography) or the like obtained by contrasting the blood vessel position obtained by detecting the movement of blood is a kind of motion contrast. A specific example of processing for acquiring a three-dimensional motion contrast image will be described later.

<Display processing of tomographic image in arbitrary cross section>
The graphic obtained by visualizing the three-dimensional OCT data may be a tomographic image. For example, a two-dimensional image based on the signal intensity distribution at an arbitrary cross section in the acquisition range of the three-dimensional OCT data may be generated as a tomographic image by the control unit 70. Such a tomographic image is not limited to an image showing a cross section in a certain scan line, for example. For example, an image showing a cross section that obliquely crosses a plurality of scan lines may be formed by the control unit 70 as a tomographic image. Further, the cross section relating to the tomographic image may be either a plane or a curved surface. The tomographic image may be a motion contrast image.

  For example, in the present embodiment, a real-time tomographic image on an arbitrary cross section may be displayed on the monitor 75. The position of the cross section may be determined in advance. Further, the position of the cross section may be a position selected by the control unit 70 from the acquisition range of the three-dimensional OCT data based on a signal from the operation unit 74 (selection process). The signal from the operation unit 74 may be a signal for designating a cross section desired by the examiner. As a result of selecting the position of the cross section based on the signal from the operation unit 74, a tomographic image showing a cross section corresponding to the selected position is displayed on the monitor 75 by the control unit 70. As a result, the state of the tissue in the desired cross section can be observed by a real-time tomographic image generated based on the three-dimensional OCT data.

  Here, a specific example of the operation of the apparatus when the position of the cross section shown as the tomographic image is selected from the acquisition range of the three-dimensional OCT data based on the signal from the operation unit 74 will be described with reference to the drawings. I will explain.

  For example, as illustrated in FIG. 5, the control unit 70 may display a three-dimensional image G1 based on the three-dimensional OCT data on the monitor 75 in advance. The three-dimensional image G1 is used to confirm the position of a cross section shown as a tomographic image when the examiner operates the operation unit 74. The examiner may operate a pointing device (a kind of operation unit 74) or the like to specify the position of the cross section on the three-dimensional image G1. For example, in the example of FIG. 5, the position of the cursor C <b> 1 moved on the three-dimensional image G <b> 1 is displaced according to the operation of the operation unit 74. In this example, a cross section for acquiring a tomographic image is determined according to the position of the cursor C1. For example, the cursor C1 shown in FIG. 5 simulates a cross section, and a tomographic image at this cross section is displayed. In the example of FIG. 5, the cursor C <b> 1 is translated and rotated according to the operation of the operation unit 74. Thereby, the examiner can designate a desired cross section.

<Front image display processing>
Further, the graphic obtained by visualizing the three-dimensional OCT data may be a front image based on the three-dimensional OCT data, for example. The front image based on the three-dimensional OCT data is obtained by, for example, integrating the signal intensity distribution in the depth direction in the Z direction at each XY position of the three-dimensional OCT data (so-called integrated image). Of course, the front image may be acquired by a process different from the integration process. For example, the front image may be acquired based on some data regarding the depth direction in the three-dimensional OCT data. Such a front image may be, for example, a front image relating to a part of layers constituting the fundus (for example, the retinal surface layer shown in FIG. 4 or a specific layer other than the surface layer). Or a front image at a certain depth (for example, a C-scan image showing a signal intensity distribution at a certain depth). In addition, when the front image regarding a one part layer is acquired, the control part 30 performs a segmentation process with respect to three-dimensional OCT data, and pinpoints the boundary for every layer. And a front image is formed based on the information of the boundary part specified by the segmentation process.

  Note that the front image based on the three-dimensional OCT data may be a motion contrast image.

  The front image is not limited to the two-dimensional display mode shown in FIG. 4 (that is, a mode in which the XY direction on the fundus is associated with the vertical and horizontal directions on the screen). For example, the front image may be displayed in a manner that reflects the three-dimensional shape of the layer. That is, the front image may be displayed in a curved surface shape. Further, in this case, the front image may be a graphic in which a part of the layers is perspective.

  As described above, when a real-time front image is displayed on the monitor 75, the front image of the tissue at any depth may be shown as the front image. The position in the depth direction for the location where the front image is shown may be determined in advance. Further, the position in the depth direction for the location where the front image is shown may be a position selected by the control unit 70 based on a signal from the operation unit 74 (selection process). The signal from the operation unit 74 may be a signal for designating a position desired by the examiner. As a result of the selection of the position in the depth direction based on the signal from the operation unit 74, the front image for the selected position is displayed on the monitor 75 by the control unit 70. As a result, the state of the tissue at the depth desired by the examiner can be observed by a real-time front image.

  By the way, as described above, the front image based on the three-dimensional OCT data is considered to be at least a front image of a part of layers constituting the fundus and a front image at a certain depth. .

  When the front image is a front image for a part of the layers, the control unit 70, more specifically, the control unit 70 selects one of a plurality of layers constituting the fundus and shows it as the front image. It is. More specifically, a boundary between a plurality of layers constituting the fundus may be detected by segmentation processing into three-dimensional OCT data, and any one of the detected boundaries may be selected. In this way, position selection in the depth direction may be performed for the location where the front image is shown. Then, the control unit 70 may form a front image of the selected layer and display it on the monitor 75.

  On the other hand, when the front image based on the three-dimensional OCT data is a front image at a certain depth, the control unit 70 can detect any one of the depth directions within the acquisition range regarding the depth direction of the three-dimensional OCT data. You may select the position of the depth direction about the location where a front image is shown by selecting a coordinate. Then, a front image indicating a horizontal plane at the selected coordinate in the depth direction (for example, a C scan image) may be formed and displayed on the monitor 75.

  Here, refer to FIG. 6 for a specific example of the operation of the apparatus when the position in the depth direction at the location where the front image based on the three-dimensional OCT data is shown is selected based on the signal from the operation unit 74. To explain.

  For example, as illustrated in FIG. 6, the control unit 70 may display in advance a graphic G <b> 2 indicating an acquisition range regarding the depth direction of the three-dimensional OCT data on the monitor 75. The graphic G2 is used to confirm the position (position in the depth direction) of the tissue desired to be shown in the front image when the examiner operates the operation unit 74. In the example of FIG. 6, a three-dimensional image of the eye to be examined is used for the graphic G2. The examiner may operate a pointing device (a kind of the operation unit 74) or the like to specify a location where the front image is shown on the graphic G2. For example, in the example of FIG. 6, the position of the cursor C <b> 3 that moves in the depth direction in the graphic G <b> 2 is displaced with respect to the graphic G <b> 2 according to the operation of the operation unit 74. In this example, the location where the front image is shown is determined according to the position of the cursor C3. More specifically, a front image at the depth where the cursor C3 is arranged is generated by the control unit 70 and displayed on the monitor 75. In the example of FIG. 6, the cursor C3 imitates a horizontal plane (that is, a plane orthogonal to the depth direction) in coordinates in the depth direction, and a front image on the horizontal plane is displayed.

  The graphic G2 is not limited to a three-dimensional image. For example, a tomographic image obtained at a certain scan line, a graph indicating a depth profile obtained at a certain point, and an indicator (for example, a number line) ) And other graphics.

  The method for designating a cross section relating to a two-dimensional image is not necessarily limited to the one described above. For example, when the examiner selects the passing coordinates of an arbitrary curved surface using a pointing device or the like via a three-dimensional image displayed on the monitor 75, a two-dimensional image having the curved surface as a cross section is displayed on the control unit 70. May be displayed.

  By the way, the examples of the three-dimensional image and the two-dimensional image are not limited to those described above. For example, the three-dimensional image is not limited to, for example, a visualization of the entire acquisition range of the three-dimensional OCT data, and the first cross section and the first cross section in the acquisition range of the three-dimensional OCT data are The graphic which selectively visualized the area | region pinched | interposed between a different 2nd cross section may be sufficient. The first cross section and the second cross section here may be specified, for example, in the same manner as in the case where each specifies a cross section of a two-dimensional image, or one cross section may be specified. In this case, the other may be set automatically. Further, further, the three-dimensional image displayed in real time may be an arbitrary three-dimensional region in the acquisition range of the three-dimensional OCT data, and the entire acquisition range and two cross sections. It is not limited to any of the regions surrounded by

  Moreover, the information regarding the area | region pinched | interposed into the 2nd cross section different from a 1st cross section among three-dimensional OCT data is averaged regarding one certain direction (specifically, depth direction), for example. Accordingly, the control unit 70 may form a two-dimensional image regarding a region sandwiched between the second cross section different from the first cross section.

<Analysis processing for 3D OCT data>
In the present embodiment, various types of processing (for example, analysis processing and image processing) on the three-dimensional OCT data are also performed by the control unit 70. For example, the control unit 70 performs an analysis process on each three-dimensional OCT data generated as needed. As a result, the control unit 70 outputs a real-time analysis result of the three-dimensional OCT data generated at any time. The “output” here may be a display output to the monitor 75, for example. Further, it may be an output to an ophthalmic surgical apparatus (for example, an ophthalmic surgical robot, an ophthalmic laser surgical apparatus, an ophthalmic laser photocoagulator, or the like) that operates in parallel with imaging by OCT1. The analysis result output from the control unit 70 may be used as a signal for controlling the operation of the ophthalmic surgical apparatus (details will be described later). First, the case where the analysis result is displayed on the monitor 75 will be mainly described.

  The processing result of the analysis processing may be obtained by processing at least two (in other words, at least two frames) of three-dimensional OCT data among time-series three-dimensional OCT data. Here, the at least two three-dimensional OCT data are three-dimensional OCT data acquired at different timings.

<Real-time display of motion contrast image>
As this processing result, the three-dimensional motion contrast data of the eye E may be acquired. For example, a moving image based on a motion contrast image that is a graphic obtained by visualizing three-dimensional motion contrast data may be displayed on the monitor 75 as a processing result of the analysis processing.

  The three-dimensional motion contrast data is acquired based on a plurality of raster scans performed at different times for a region having the fundus. More specifically, the control unit 70 acquires a complex OCT signal by performing a Fourier transform on a signal (OCT signal) output from the detector 120. For example, the complex OCT signal is stored in the memory 72 every time a raster scan is performed. Here, the complex OCT signal for one cycle of the raster scan is stored in the memory 72, so that one unit (in other words, one frame) of three-dimensional OCT data is obtained. Then, the control unit 70 processes complex OCT signals for the same position (in other words, the same xy coordinates), which are complex OCT signals having different raster scan timings, and thereby the depth direction in the xy coordinates. Get a profile of. This process is performed for each position where the A scan data is acquired (in other words, for each point, for each xy coordinate), thereby acquiring three-dimensional motion contrast data in the raster scan range. Thus, in the present embodiment, three-dimensional motion contrast data is acquired as a processing result of at least two three-dimensional OCT data having different raster scan timings.

  As a method of processing the complex OCT signal, for example, a method of calculating a phase difference of the complex OCT signal, a method of calculating a vector difference of the complex OCT signal, a method of multiplying the phase difference and the vector difference of the complex OCT signal, etc. Are known, and any of these may be used. In the following description, a method for calculating the phase difference will be described as an example.

  The three-dimensional motion contrast data obtained as described above indicates, for example, the three-dimensional structure of blood vessels. The control unit 70 may sequentially generate a motion contrast image based on the three-dimensional motion contrast data and display the motion contrast image on the monitor 75 sequentially. In addition, the graphic indicating the three-dimensional structure of the blood vessel may be superimposed and displayed on the three-dimensional OCT image (the image indicating the three-dimensional reflection intensity distribution as described above) by the control unit 70. Thereby, the three-dimensional structure of the blood vessel may be displayed on the monitor 75 in real time. In addition, by comparing the three-dimensional motion contrast data obtained in time series with the past three-dimensional motion contrast data, it is possible to detect a bleeding site that has occurred during the repeated acquisition of the three-dimensional OCT data. The detected bleeding site may be highlighted in the graphic indicating the three-dimensional structure of the blood vessel. For example, during a surgical operation, a bleeding point is quickly grasped by a doctor or the like, so that it is easy to perform a rapid treatment for bleeding.

<Analysis of blood flow pulsation>
In the analysis process for the three-dimensional OCT data, an analysis process related to blood flow pulsation may be executed. For example, when the control unit 70 further processes the three-dimensional motion contrast image, information regarding blood flow pulsation may be acquired as a processing result of the analysis processing. As a specific example of information related to blood flow pulsation, for example, information indicating at least one of the direction of blood flow, the speed of blood flow, the flow rate of blood flow, the pressure due to blood flow, and the pulse may be used. Also, it may be information indicating any of these in time series.

  As shown in FIG. 5, such a processing result is sent to the monitor 75 together with a graphic visualizing real-time three-dimensional OCT data (in the example of FIG. 5, a three-dimensional image and a motion contrast image of a certain cross section). May be displayed. At this time, the control unit 70 may sequentially acquire real-time processing results corresponding to the graphic displayed on the monitor 75 and display the processing results on the monitor 75. In this case, the monitor 75 displays at least a graphic obtained by visualizing the three-dimensional OCT data and at least a processing result corresponding to the graphic. As a display example of the processing result, a numerical value may be used, or a graph (for example, a trend graph) representing a change of the numerical value with time may be used, or another display mode may be used. Thus, in the present embodiment, blood flow information useful in diagnosis can be obtained in real time from a wide range where raster scanning is performed.

<Measurement of blood flow>
In the present embodiment, the absolute velocity of blood flow may be obtained using a three-dimensional structure of a blood vessel obtained from a three-dimensional motion contrast image and three-dimensional OCT data obtained by a plurality of raster scans. .

  For example, the blood flow direction at each position and the diameter of the blood vessel at each position are obtained from the three-dimensional structure of the blood vessel based on the three-dimensional motion contrast image. The blood flow direction of the blood vessel may be obtained by thinning the three-dimensional structure of the blood vessel as described above. For thinning, for example, morphology processing, distance conversion processing, or existing algorithms such as Hilditch and Deutsch may be used.

  Here, the Doppler phase shift at each position is derived based on the three-dimensional OCT data obtained by a plurality of raster scans. At this time, when a constant raster scan is repeated, a value that is an integral multiple of the raster scan period can be adopted as the time interval in the Doppler phase shift. The time interval is an OCT signal acquisition interval at the same position.

  For example, from two three-dimensional OCT data obtained by two consecutive raster scans, a Doppler phase shift with time interval = T is obtained, and two obtained by two raster scans skipped by one period. From the three-dimensional OCT data, a Doppler phase shift with time interval = 2T is obtained. Similarly, a Doppler phase shift may be obtained in which a time interval is an integral multiple of the raster scan period.

  Based on the Doppler phase shift at each position of the blood vessel, the control unit 70 obtains the absolute velocity of the blood flow at each position. At this time, in the Doppler phase shift at each position, the time interval may be constant, or may be a value different for each position. When varying the time interval depending on the position, for example, the control unit 70 determines the time interval according to information on the structure of the blood vessel at the point for which the Doppler phase shift is obtained, and obtains the Doppler phase shift at the time interval. May be. The information regarding the structure of the blood vessel may be at least one of the diameter of the blood vessel (blood vessel diameter), the direction of the blood vessel, and the presence or absence of branching.

  Alternatively, a plurality of Doppler phase shifts having different time intervals may be obtained for one point, and the absolute velocity of blood flow at the point may be obtained based on the plurality of Doppler phase shifts.

  In the present embodiment, the control unit 70 may calculate the absolute velocity of blood flow in each part of the blood vessel in real time. For example, every time three-dimensional OCT data based on a new raster scan (for convenience, the first raster scan) is obtained, the three-dimensional OCT data based on the first raster scan, the first three-dimensional OCT data, Second 3D OCT data whose time interval is the first time interval, and third 3D OCT data whose time interval between the first 3D OCT data is the second time interval (for example, From the time intervals = T, 2T, 3T...), The absolute velocity of blood flow at each location may be calculated.

  The distribution of the absolute velocity at each location obtained in this way may be displayed on the monitor 75 as a color map, for example. Further, the control unit 70 may compare the absolute velocity of the blood flow in the normal eye with the absolute velocity of the blood flow in the eye E obtained by calculation. For example, the control unit 70 may output the difference information as numerical information or a difference map by taking the difference between the two. Note that the absolute velocity of blood flow in the normal eye may be stored in the memory 72 in advance, for example.

  Further, the position of the blood vessel where the absolute velocity of the blood flow is calculated is determined by the examiner on the blood vessel image displayed on the screen (for example, the front based on the 3D motion contrast image, the tomographic image, and the 3D OCT data). Any one of images) may be designated. For example, a location where the absolute velocity of the blood flow is calculated in the image displayed on the monitor 75 may be designated based on the examiner's operation on the operation unit 74. The examiner may operate a pointing device (a kind of operation unit 74) or the like to designate a blood vessel for which an absolute velocity of blood flow is desired on the blood vessel image. For example, in the example of FIG. 5, the position designation is performed according to the position of the cursor C <b> 2 that is displaced according to the operation of the operation unit 74. In this case, for example, the control unit 70 may calculate the absolute velocity of the blood flow at the designated location. Alternatively, the absolute velocity of the blood flow at each position may be calculated in the background, and the calculation result at the location specified by the examiner may be selectively output (for example, displayed). Also in this case, the comparison processing with the absolute velocity of blood flow in the normal eye as described above may be performed.

  Such calculation of the absolute velocity of the blood flow is executed each time three-dimensional OCT data based on a new raster scan is obtained, whereby the calculation result may be updated as needed. However, the frequency of the calculation of the absolute velocity of the blood flow is not limited to each time three-dimensional OCT data is acquired for one frame, but may be every time a plurality of frames are acquired.

  The calculation result of the absolute velocity of the blood flow may be displayed on the monitor 75. The calculation result may be displayed as at least one of a numerical value and a graphic, for example.

  Note that the three-dimensional OCT data of a plurality of frames is not necessarily required for analyzing blood flow pulsation. For example, the control unit 70 controls the optical scanner 108 and repeatedly acquires two-dimensional OCT data regarding the same cross section, thereby acquiring information regarding blood flow pulsation regarding the cross section. The repetitive scanning of the cross section at this time may be performed, for example, between raster scans for acquiring three-dimensional OCT data. As a result, information about the pulsation of blood flow in real time can be obtained substantially simultaneously with the three-dimensional OCT data. In addition, a plurality of two-dimensional OCT data with a short scan line scan interval may be acquired for the same cross section by repeatedly scanning each scan line a predetermined number of times in one cycle of raster scan. The control unit 70 may analyze information related to blood flow pulsation in each scan line by processing a plurality of two-dimensional OCT data.

<Other analysis processes>
As described above, a specific example in which processing is performed using at least two (in other words, at least two frames) three-dimensional OCT data as analysis processing performed on three-dimensional OCT data acquired as needed. However, it is not necessarily limited to this. For example, an analysis process for processing time-series three-dimensional OCT data for each frame may be performed.

<Real-time thickness measurement>
For example, the control unit 70 may perform analysis processing related to the thickness of the eye E in the tissue. The control unit 70 analyzes the thickness of the eye E in the tissue based on the three-dimensional OCT data generated as needed. And you may output the information regarding thickness as an analysis result. The thickness of the tissue may be, for example, the layer thickness at the fundus or the thickness of the anterior eye tissue. The thickness at each position may be obtained by the analysis process, and a map showing the two-dimensional distribution of the thickness in the tissue of the eye to be examined in real time may be obtained as the analysis result. The map may be displayed on the monitor 75. The real-time thickness map is used to detect changes in thickness caused by, for example, pressure applied to the eye E or operations that affect the tissue thickness such as refractive surgery and cataract surgery. It may be used when a person observes in real time. The surgery here may be an operation using an ophthalmic laser surgical apparatus. In this case, the OCT 1 is a tonometer (for example, a tonometer) that applies pressure to the eye E or an ophthalmic laser. A surgical device may be provided. And each apparatus may be controlled so that pressure application or laser irradiation may be performed while three-dimensional OCT data is continuously acquired in OCT1. Further, the control unit 70 may output an analysis result regarding the thickness to the ophthalmic laser surgical apparatus in order to control laser irradiation in the ophthalmic laser surgical apparatus.

<Extraction of information on coagulation spots>
Further, the control unit 70 analyzes the coagulation spots of the photocoagulation laser formed in the eye to be examined based on the three-dimensional OCT data generated as needed, and the size information of the coagulation spots and the coagulation spots in the eye E to be examined. At least one of the position information may be output as a real-time analysis result. Coagulation spots are, for example, regions having different luminance relative to surrounding tissues in a graphic (three-dimensional image or two-dimensional image showing a certain cross section) in which three-dimensional OCT data acquired in real time is visualized. It can be detected by image processing to a graphic. In addition, at least one of the size information of the detected coagulation spots and the position information of the detected coagulation spots in the eye E can be specified by image processing for graphics. The size information may be information regarding at least one of the radius of the coagulation plaque, the length in the depth direction, the volume, and the volume. Further, the position information may be information for specifying the formation position of the coagulation spot in the eye E, and may be numerical information such as coordinate information, for example. Further, the position information may be image information, for example, a graphic obtained by visualizing three-dimensional OCT data, and further a graphic in which a formation position of a coagulation spot is emphasized. These pieces of information are output in real time as analysis results.

  For example, in OCT1 in which such an analysis process is performed, information for evaluating the irradiation result is obtained as an analysis result by the above analysis process immediately after the photocoagulation laser irradiation. For this reason, it is thought that workability in the photocoagulation laser irradiation work is improved by utilizing the analysis result.

  In this case, the OCT 1 may include a photocoagulation laser device that irradiates the eye E with a photocoagulation laser. Then, each unit may be controlled by the control unit 70 so that laser irradiation is performed while three-dimensional OCT data is continuously acquired in the OCT 1. In addition, the control unit 70 may output an analysis result regarding the coagulation spots to the photocoagulation laser device in order to control laser irradiation in the photocoagulation laser device.

<Analyzing process for peeling of fundus layer>
In addition, for example, the control process may be performed in real time by the control unit 70 regarding the separation of the layer on the fundus of the eye E. In this analysis processing, it is assumed that three-dimensional OCT data including the fundus oculi in the data acquisition range is acquired by the OCT 1 as an analysis target. And the peeling location of the layers constituting the fundus is analyzed based on the three-dimensional OCT data generated at any time, and as a result (analysis result), the presence / absence of the peeling location between the layers, the position of the peeling location, Information (referred to as peeled portion information) indicating at least one of them may be output. Obtaining peeling site information in real time is useful, for example, in vitreous surgery. In addition, as information which shows the position of a peeling location, it is the information for pinpointing a peeling location regarding one or both of a xy direction and a depth direction. The information for specifying the peeling location in the depth direction may be numerical information indicating the position of the peeling location in the depth direction, or information specifying at least one of the two layers peeled from each other. May be. When applied to vitreous surgery, the above-described analysis processing may obtain at least the peeling state of the inner boundary membrane (ILM) as a real-time analysis result.

  In addition, the display output of peeling location information may be performed with respect to the monitor 75. FIG. On a graphic (three-dimensional image or two-dimensional image showing a certain cross section) obtained by visualizing the three-dimensional OCT data, at least a part corresponding to the peeled part may be highlighted. In addition, in order to distinguish each layer, highlighting may be performed also about the boundary of another layer in the aspect different from the highlighting with respect to a peeling location.

  If an operation for peeling the layer is performed by a surgical robot or the like, the control unit 70 outputs peeling part information (that is, an analysis result) to the surgical robot in order to control the peeling operation in the surgical robot. May be.

<Analysis processing concerning the distance between the tissue of the eye and the instrument>
In addition, for example, the control unit 70 sets the interval in the depth direction between the instrument used for diagnosis, treatment, or surgery of the eye E and the tissue of the eye E to the generated three-dimensional OCT data as needed. Based on the analysis, information on the distance between the instrument and the tissue of the eye E may be output as a real-time analysis result. In this analysis process, it is assumed that three-dimensional OCT data including the above-described instrument together with the tissue of the eye E to be acquired is acquired by the OCT 1 as an analysis target.

  As said instrument, various instruments, such as injectors, such as a probe, forceps, a microkeratome, and IOL, can be assumed. In addition, the tissue of the eye to be analyzed whose distance from the instrument is analyzed may be selected from each part of the eye E via the operation unit 74, for example. Further, it may be a predetermined tissue (for example, any one of the cornea and the retina).

  The analysis result regarding the interval between the tissue of the eye to be examined and the instrument may be displayed and output to the monitor 75. For example, numerical information indicating the interval as a numerical value may be displayed, or a graphic such as an indicator may be displayed.

  By the way, when the instrument is made of, for example, metal, the measurement light is reflected on the surface (light source side surface) of the instrument, and the entire shape of the instrument may not be detected from the three-dimensional OCT data. On the other hand, for example, the dimension information of the instrument (more specifically, dimension information based on the surface of the instrument on which the measurement light is reflected may be acquired in advance), and the dimension information is used to The interval between the eye E and the tissue may be analyzed. Further, in this case, in the three-dimensional OCT data, a part where the position information of the tissue cannot be obtained may occur due to the measurement light being blocked by the instrument. The position information of the tissue obstructed by the instrument may be estimated (or complemented) by various methods, and the distance between the tissue of the eye to be examined and the instrument is analyzed based on the estimated position information. May be. For example, the control unit 70 uses the 3D OCT data acquired in a state where the tissue of the eye to be examined is not obstructed by the instrument, and supplements the data regarding the tissue obstructed by the instrument in the 3D OCT data acquired as needed. Then, an analysis of the distance between the tissue and the instrument may be performed.

  If the instrument is being moved by a surgical robot or the like, the control unit 70 outputs an analysis result regarding the distance from the instrument to the surgical robot in order to control the movement of the instrument in the surgical robot. Also good.

<Modified example of structure and control of optical scanner>
In the description of the above embodiment, a resonant scanner is used as the optical scanner 108a for main scanning in FIG. 1, and scanning of measuring light by the forward movement of the resonant scanner and scanning of measuring light by the backward movement are alternately performed. Was described as a main embodiment (see FIG. 2). However, as described above, various optical scanners other than the resonant scanner can be applied to the main scanning optical scanner according to the present disclosure. For example, as in a specific example described later, one or a plurality of galvanometer mirrors may be used as an optical scanner for main scanning. The galvanometer mirror is characterized by high controllability and a high degree of freedom in scan pattern, and the scan speed can be changed by control. Galvano mirrors can be obtained at a relatively low cost.

  In the description of the above embodiment, the case where the measurement light is scanned on the eye to be examined by the raster scan as illustrated in FIG. 2 has been mainly described. However, it is not necessarily limited to this. For example, in the method shown in FIG. 2, the forward movement and the backward movement are alternately performed in the main scanning optical scanner, and the measurement light is scanned by each of the forward movement and the backward movement. On the other hand, as in a specific example described later, when the main scanning optical scanner performs a reciprocating operation, a method of obtaining A scan data based only on the forward movement of the forward movement and the backward movement is applied. (See FIG. 7). In this scanning method, the position where the A scan is performed is less likely to be shifted between adjacent scan lines, as compared with the method in which the measurement light is scanned in each of the forward movement and the backward movement (that is, the B scan is performed). Here, “the operation of the optical scanner that moves the irradiation position of the measurement light on the eye to be examined in one direction” is defined as “outward movement”, and “the irradiation position of the measurement light on the eye to be examined is defined as “Operation of the optical scanner that moves in the direction opposite to one direction” is defined as “return movement”. That is, the forward movement and the backward movement need not be uniquely defined by the design specifications of the optical scanner or the optical system.

  Of course, a scanning method other than the raster scan (for example, a Lissajous scan) may be applied as the scanning method of the measurement light with respect to the eye to be examined. In the case of the Lissajous scan, it is not always necessary to perform the reciprocating operation in the galvanometer mirror as quickly as in the case of the raster scan. Therefore, even if the A-scan acquisition period is 300 kHz or more, the galvanometer mirror can be used to transmit the measurement light. Easy to scan. The scanning pattern of the measurement light in the Lissajous scan may be, for example, a cycloid shape, a trochoid shape, a spiral shape, or another pattern. Furthermore, the scanning method of the measurement light is not limited to two-dimensional scanning such as raster scanning and Lissajous scanning, but may be one-dimensional scanning.

  An example in which one or a plurality of galvanometer mirrors is applied to an optical scanner for main scanning will be described below. In the following examples, the measurement light is scanned on the fundus unless otherwise noted. In the description of this embodiment, the control unit 70 acquires A scan data at a cycle of 300 kHz or more, as in the above embodiment. In the embodiment, the control unit 70 may control the galvanometer mirror as follows. That is, by repeatedly reciprocating the galvanometer mirror with a fixed swing angle, the measurement light is continuously scanned twice or more in the main scanning direction. At this time, drive control is performed so that the time difference in the start timing of each scan is 5 milliseconds or less. The swing angle of the galvanometer mirror at this time (the above-mentioned “constant swing angle”) corresponds to a distance of about several millimeters on the fundus. For example, it may correspond to a distance of about 9 mm or more.

  Then, the control unit 70 may process A scan data obtained by two or more scans. When repeated scanning is performed on one scan line, a data set composed of a plurality of A scan data is acquired each time the measurement light is scanned one way on the scan line. Then, the control unit 70 may process a plurality of data sets acquired in time series with respect to one scan line. The process referred to here may be, for example, a process of obtaining an added image of tomographic images related to a scan line (the added image includes an added average image). Moreover, the process which produces | generates and acquires the angiographic image (OCT angiography) regarding a scan line may be sufficient.

  On the other hand, when the measurement light is scanned with respect to a plurality of different scan lines, the control unit generates three-dimensional OCT data based on the A scan data obtained by scanning the measurement light with respect to the plurality of scan lines. Also good. In this case, the control unit 70 drives and controls the sub-scanning optical scanner together with the galvanometer mirror that is the main-scanning optical scanner.

<Example of applying one galvanometer mirror as an optical scanner for main scanning>
Here, a specific example in which only one galvanometer mirror is provided as an optical scanner for main scanning will be described. In this specific example, the OCT data is acquired based only on the forward movement among the reciprocating movements of the galvanometer mirror which is an optical scanner for main scanning.

  Here, the galvanometer mirror is considered to require a time of at least about 1 millisecond for each of the forward movement and the backward movement. Further, there is a trade-off relationship between shortening the time required for one main scan and the positioning accuracy of the A scan. Therefore, out of the reciprocating operation of the galvanometer mirror, the backward movement may be executed in a time of about 1 millisecond, and the forward movement may be executed in the remaining time. In other words, when the galvano mirror travels in the range of about 1 to 4 milliseconds, when the galvano mirror is repeatedly reciprocated at a fixed swing angle, the time difference at the start timing of each scan is 5 mm. It can be less than a second. Further, assuming that the A scan data acquisition cycle is 300 kHz, approximately 300 points to 1200 points of A scan data can be acquired for each forward movement by the galvanometer mirror.

  In addition, there is the following technical significance for setting the time difference at the start timing of each scan to 5 milliseconds or less.

  For example, OCT angiography in which a blood vessel is well contrasted is easily acquired. For example, according to Non-Patent Document 1 below, in the OCT angiography of the fundus, the time interval is preferably set in the range of 1 to 5 milliseconds (more preferably, 2.5 to 5 milliseconds). Results in the millisecond range) are shown. Here, when the galvano mirror is used as an optical scanner for main scanning, since at least 2 milliseconds are required for one reciprocation of the galvano mirror, in this embodiment, the time interval (time difference at the start timing of scanning) is It can be realized in the range of 2 milliseconds to 5 milliseconds.

In Non-Patent Document 1, a very short time interval of 1 millisecond or the like is realized by a method called backstitched B-scans. In backstitched B-scans, when scanning the measurement light on one scan line, scanning is performed by turning back the galvanomirror in small increments a plurality of times in a manner that advances two steps and returns one. However, since this method requires a time interval each time the galvano mirror is turned back in small increments, scanning per scan line is likely to take time. On the other hand, in this embodiment, the A-scan data is acquired at 300 kHz or higher, so that the OCT data of several hundred or more points per scan line can be obtained without switching back the direction of the galvanometer mirror during the forward movement. Can be acquired at the above time interval. That is, OCT angiography for the scan line can be obtained by performing at least two scans that uniformly move the measurement light irradiation position with respect to one scan line.
That is, compared with non-patent literature, scanning for obtaining OCT angiography is realized at higher speed while controlling the galvanometer mirror more easily.

Non-Patent Document 1: “Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans” Boy Braaf, Koenraad A. Vermeer, Kari V. Vienola, and Johannes F. de Boer; Optics Express Vol 20, Issue 18, pp. 20516-20534 (2012)
Further, for example, the influence of eye movement in each scan is suppressed. Eye movements such as fixation fine movement tend to have smaller amplitude (amount of eye movement) as the period becomes shorter. For example, according to the following Non-Patent Document 2, the amplitude is reduced to 0.5 arcmin (the fundus is 2.5 micrometers or less) in a region of 10 Hz or more. Since one scan for one scan line is executed in a time of about 1 to 4 milliseconds based on the forward movement of the galvanometer mirror, the measurement light is scanned accurately on the target scan line. Cheap.

Non-Patent Document 2: “Real-time eye motion compensation for OCT imaging with tracking SLO”, Kari V. Vienola, Boy Braaf, Christy K. Sheehy, Qiang Yang, Pavan Tiruveedhula, David W. Arathorn, Johannes F. de Boer, and Austin Roorda; Biomedical Optics Express, Vol. 3, issue 11, pp. 2950-2963, (2012),
Also, in view of the response to the stimulus and the tissue change due to the pulsation, it is desirable that the time difference at the start timing of each scan is short. For example, OCE (Optical Coherence Elastography) is known, and there is an examination for observing tissue deformation based on stimulation by an air puff. For example, in the case of the anterior segment, the deformation occurs within a few milliseconds, and the elastic wave spreads over a wide range. For example, when the imaging apparatus 1 is applied as the anterior segment OCT, if the time required for each scan is set in a range of about 1 to 3 milliseconds, It is considered that the anterior segment OCT data can be obtained within a sufficient scanning range and at time intervals.

  In addition, for example, when a raster scan is performed and 3D OCT data is generated and acquired as a result, a raster scan of about 1 second or less is performed with 256 points or more on one side in the xy direction and the other. A scan data in a rectangular area of 512 points or more with respect to each side can be acquired based on a raster scan in a time of about 1 second or less.

  In the description of the above embodiment in which the resonant scanner is applied as the optical scanner for main scanning, the case where the high-speed A-scan is used to continuously acquire time-series three-dimensional OCT data has been described. However, it does not necessarily have to be acquired continuously. For example, high-speed A-scan may be used in order to complete the acquisition operation of 3D OCT data in a short time. In this case, the operation of acquiring the three-dimensional OCT data may be started when a predetermined trigger signal is input to the control unit 70. The trigger signal may be input based on a release operation by the examiner.

  By the way, although the frequency of human blinking is large among individuals, it is distributed around 20 to 30 times (see, for example, Non-Patent Document 3 below). In this embodiment, the measuring light can be scanned in a sufficiently short time with respect to the blinking time interval in a range of several hundred points or more per side. As a result, it is considered that the burden such as opening of the subject is satisfactorily suppressed.

Non-Patent Document 3: "Blink frequency-(Part 1) Number of blinks in normal adults"; Minami Kumata, Yamashiro, Minamitsu, Date of issue 1957/7/15; Clinical ophthalmology, Volume 11 No. 7 For example, the control unit 70 may perform drive control of the galvanometer mirror so that the time of one forward movement is 3 milliseconds or less. For example, when A scan data is acquired with a period of 300 kHz or more, the time of forward movement per time is set to 3 milliseconds or less, so that 300 or more scan lines per second are set. On the other hand, the measurement light is scanned. At this time, it is preferable that the drive control of the galvanometer mirror is performed so that one forward movement in the galvanometer mirror is performed in the range of 2 milliseconds to 3 milliseconds. In this case, each A scan can be performed at a desired position with good accuracy.

  Moreover, the control part 70 may acquire A scan data in the range of 350 kilohertz or more and 500 kilohertz or less, for example. In this case, the speed of the forward movement in the galvanometer mirror may be controlled within a range in which A-scan data of 1024 points or more can be acquired by one forward movement. As an example, when the A scan data acquisition cycle is about 400 kHz, the dimensional OCT data having at least about 1024 points in the main scanning direction and about 512 points in the sub-scanning direction is a raster scan of 2 seconds or less per cycle. Can be obtained by.

<Example of applying two galvanometer mirrors as an optical scanner for main scanning>
When a plurality of galvanometer mirrors are provided as main scanning optical scanners, the deflection directions of the galvanometer mirrors used for main scanning may be common to each other. Moreover, each galvanometer mirror may be arrange | positioned on the optical path without a branch (serial arrangement | positioning), and may each be arrange | positioned on the several branched optical path (parallel arrangement | positioning). When three or more galvanometer mirrors are applied as the main scanning optical scanner, a combination of a serial arrangement and a parallel arrangement may be used.

  In the case where a plurality of galvanometer mirrors are provided as main scanning optical scanners, the time required for one forward movement of each galvanometer mirror is as described above <one galvanometer mirror as the main scanning optical scanner. The range shown in Applied Example> may be used.

  Here, FIGS. 8, 10, and 11 show specific examples when two galvanometer mirrors arranged in parallel or in series are applied to the optical scanner for main scanning. 8, FIG. 10 and FIG. 11 show examples of modifications to the embodiment shown in FIG. 8, 10, and 11, a part of the OCT optical system 100 that is a main difference from the embodiment of FIG. 1 is extracted. That is, a portion corresponding to between the fiber 132 and the eye E to be examined is different between FIG. 1 and FIGS. In the description of the modification example, the same reference numerals as those in FIG. 1 are used for the configuration common to the embodiment in FIG. 1, and detailed description thereof is omitted.

<Specific modification of main scanning optical scanner (parallel arrangement)>
First, the modification example shown in FIG. 8 will be described. In the modification example of FIG. 8, the OCT optical system 100 performs two-axis optical scanning with the optical scanner 208. Further, the OCT optical system 100 in the modification example is provided with an optical switch 210 (an example of “light selection unit”). In FIG. 8, the optical switch 210 is disposed between the emission end of the fiber 132 and the optical scanner 208. Further, the measurement light passing through the optical scanner 208 is irradiated to the eye E through the objective optical system 106 as in the embodiment of FIG.

  The optical scanner 208 has two galvanometer mirrors 208a1 and 208a2 as optical scanners for main scanning. Further, the optical scanner 208 is provided with an optical scanner 208b for sub-scanning. In FIG. 8, the galvanometer mirrors 208a1 and 208a2 are arranged on the eye E side of the optical scanner 208b for sub scanning. A lens 208c is provided between the optical scanner 208b for sub-scanning and the galvanometer mirrors 208a1 and 208a2 for deflecting the direction of the measurement light guided from the optical scanner 208b to the galvanometer mirrors 208a1 and 208a2. It may be. In the following description, for convenience of description, it is assumed that the scanning position on the eye to be examined and the scanning range in the two galvanometer mirrors 208a1 and 208a2 are identical to each other unless otherwise specified. Further, the OCT optical system 100 includes reference optical paths corresponding to the galvanometer mirrors 208a1 and 208a2 so that information of the same depth band is indicated in the A scan data based on the measurement light that has passed through the galvanometer mirrors 208a1 and 208a2. Have In this case, the reference optical path does not need to be provided individually for each of the galvanometer mirrors 208a1 and 208a2, and may be shared. In this case, the measurement optical path is formed so that the optical path length difference between the reference light and the measurement light that has passed through the respective galvanometer mirrors 208a1 and 208a2 matches each other in the two measurement lights.

  The optical switch 210 is used as an example of a “light selection unit” to selectively guide measurement light to one of the two galvanometer mirrors 208a1 and 208a2 for main scanning. That is, the beam steering 210 switches between the state in which the measurement light is selectively guided to one of the two galvanometer mirrors 208a1 and 208a2, and the state in which the measurement light is selectively guided to the other. Note that the optical switch 210 illustrated in FIG. 8 switches the direction of light that passes (transmits or reflects) through the switch body, and thus the optical scanner that guides the measurement light is placed between the two galvanometer mirrors 208a1 and 208a2. Switch.

  An example of such an optical switch is a non-mechanical beam steering such as an LCOS type spatial light modulator (SLM). For example, it is known that an LCOS type SLM has a device capable of switching the orientation of liquid crystal molecules in the order of several tens of microseconds. That is, the beam steering state is switched in a sufficiently short time with respect to the time required for scanning the measurement light by the galvanometer mirrors 208a1 and 208a2.

  In addition to such beam steering, a so-called electronic switch, a mechanical switch, or the like can be applied as appropriate.

  Here, the detailed operation of the two galvanometer mirrors 208a1 and 208a2 and the light selector (optical switch 210) will be described with reference to the timing chart of FIG.

  In FIG. 9, in the graph relating to the galvanometer mirrors 208a1 and 208a2, the period in which the turning amount increases indicates the forward movement period, and the period in which the turning amount decreases indicates the backward movement period.

  In FIG. 9, the state of the optical switch 210 is indicated by two of [A] and [B]. [A] is a state in which the measurement light is guided to the galvano mirror 208a1 out of the galvano mirrors 208a1 and 208a2, and [B] is a state in which the measurement light is guided to the galvano mirror 208a2. In synchronization with the reciprocating operation of the two galvanometer mirrors 208a1 and 208a2, the state of the optical switch 210 is sequentially switched. That is, in the two galvanometer mirrors 208a1 and 208a2, the state of the optical switch 210 is controlled such that the measurement light is guided during each forward movement period.

  As shown in FIG. 9, the reciprocating operation of the two galvanometer mirrors 208a1 and 208a2 provided for main scanning is performed at different timings. That is, the two galvanometer mirrors 208a1 and 208a2 alternately travel in the forward direction, and the measurement light is scanned in each forward direction. At this time, in the timing chart shown in FIG. 9, one of the two galvanometer mirrors 208a1 and 208a2 selectively moves forward to scan the measurement light. Further, during the backward movement of one of the two galvanometer mirrors 208a1 and 208a2, the forward movement of the other is started. At this time, for example, one forward movement is completed, and after the state switching operation is performed in the optical switch 210, the other forward movement is started. However, in FIG. 9, the time required for switching the state of the optical switch 210 is greatly shown for convenience of illustration, but as described above, the optical switch 210 is sufficiently short in time for forward movement and backward movement. The state can be switched. Therefore, without considering the time required for switching the state of the optical switch 210, it is possible to simply start the other forward movement using the completion timing of one of the two galvanometer mirrors 208a1 and 208a2 as a trigger. Good. In addition, it is only necessary that the return movement of one of the two galvanometer mirrors 208a1 and 208a2 is performed during the return movement of the other. In this case, the movement of one of the outward movements is not necessarily started at the completion timing of the other outward movement. There is no need to For example, the scanning speed of the measurement light may be stabilized by starting the forward movement before switching the optical switch 210.

  As a result of such an operation, the measurement light can be scanned by the forward movement of one of the two galvanometer mirrors 208a1 and 208a2 during the backward movement. Thereby, the time required for the acquisition operation of the three-dimensional OCT data or the OCT angiography can be suppressed.

  For example, when the A scan data acquisition cycle is about 400 kHz, the forward movement of each galvanometer mirror 208a1, 208a2 is performed in about 2.5 milliseconds, so that the side in the main scanning direction becomes about 1000 points. Three-dimensional OCT data is obtained. In addition, raster scanning of about 1 second per cycle (1 second rounded off) results in 1024 points in the main scanning direction and 512 points in the sub-scanning direction, making it easy to process 3D OCT data. You can get it.

  Next, a modification example of FIG. 10 will be described. In the modification example of FIG. 10, the optical switch 210 in FIG. 8 is replaced with another device. Further, the fiber 132 is branched into the fiber 221 and the fiber 222 via the fiber beam splitter 220. Thereby, measurement light is simultaneously irradiated from the output ends of the fibers 221 and 222.

  The measurement light emitted from the fiber 221 is guided to the galvanometer mirror 208a1, and the measurement light emitted from the fiber 222 is guided to the galvanometer mirror 208a2. Shutters 230a and 230b are arranged on the rays of measurement light from the fibers 221 and 222, respectively. In this modification example, the shutters 230a and 230b are used as light switching units. The two shutters 230a and 230b are controlled to be opened and closed alternately between the shutters 230a and 230b. More specifically, the states of the two shutters 230a and 230b of the two galvanometer mirrors 208a1 and 208a2 are controlled so that the measurement light is guided during the respective forward movements.

  As the shutters 230a and 230b, for example, a Kerr Cell Shutter may be applied. In this case, the Kerr effect can be used to open and close at a high speed at the nanosecond level. Further, the present invention is not limited to this, and various optical shutters can be applied as the shutters 230a and 230b. Further, instead of the shutter, for example, a rotation slit may be provided as a light switching unit on the ray of measurement light from each of the fibers 221 and 222. One of the measurement lights from each of the fibers 221 and 222 passes through the slit of the rotary slit, and the other is shielded by a light shielding portion formed in the rotary slit. When the rotary slit is rotated by a motor or the like, the measurement light applied to the eye to be examined is switched.

<Specific modification of main scanning optical scanner (series arrangement)>
Next, a modification example of FIG. 11 will be described. In the modification example of FIG. 11, the OCT optical system 100 performs two-axis optical scanning with an optical scanner 308. The optical scanner 308 has two galvanometer mirrors 308a1 and 308a2 as optical scanners for main scanning. Further, the optical scanner 308 is provided with an optical scanner 308b for sub-scanning. In FIG. 11, the galvanometer mirrors 308a1 and 308a2 are arranged closer to the eye E to be examined than the optical scanner 308b for sub-scanning.

  Two galvanometer mirrors 308a1 and 308a2 provided as optical scanners for main scanning are arranged in series so that the measurement light scanned by one is further scanned by the other. Thereby, the swing angle of the measurement light can be increased as compared with the case where only one of the two galvanometer mirrors 308a1 and 308a2 is driven.

  That is, in the two galvanometer mirrors 308a1 and 308a2, the forward movement and the backward movement are controlled in synchronization. Further, the turning directions in the forward movement and the backward movement are also coincident with each other. As a result, the measurement light measured by the galvanometer mirror 308a1 is further scanned by the galvanometer mirror 308a2, and the scanning speed in the main scanning direction is amplified when only one of the two galvanometer mirrors 308a1 and 308a2 is driven. .

  Of the two galvanometer mirrors 308a1 and 308a2, the galvanometer mirror 308a2 disposed closer to the eye E may have a larger mirror size than the galvanometer mirror 308a1. When the measurement light is scanned by the galvanometer mirror 308a1, it is considered that the measurement light passes through the galvanometer mirror 308a1 at a position wider than that of the galvanometer mirror 308a1, but even in that case, the galvanometer mirror 308a2 Will surely be reflected easily.

  Further, the controller 70 does not necessarily have to drive the turning speeds of the two galvanometer mirrors 308a1 and 308a2 so as to coincide with each other. For example, one of the two galvanometer mirrors 308a1 and 308a2 that is disposed closer to the eye to be examined may be driven at a faster turning speed than the other. As described above, there is a case where one of the two galvanometer mirrors 308a1 and 308a2 disposed closer to the eye to be examined is larger than the other. Since the smaller the size of the mirror, the faster the operation, the two galvanometer mirrors 308a1 and 308a2 that are arranged closer to the eye to be examined can be driven at a faster turning speed relative to the other. It is considered that the scanning speed of the galvanometer mirrors 308a1 and 308a2 can be increased.

  As described above, the description has been given based on the embodiment, but the present disclosure is not limited to the above embodiment, and various modifications are possible.

  For example, as a result of the various processes described above, the frame rate, the resolution of the image (in other words, the number of points in each direction) in relation to the required smoothness of the moving image, measurement accuracy, analysis accuracy, etc. For both, it is assumed that a high value is required for the above exemplified values, or that a low value is also satisfied. For this reason, the values exemplified above may be changed as appropriate in relation to the required measurement accuracy and analysis accuracy. For example, the technique of the present disclosure may be applied to an apparatus having an A scan data acquisition period of less than 300 kHz in a range where a certain effect can be obtained.

  In the above-described embodiment, the case where the three-dimensional OCT data relating to the fundus of the eye to be examined is exclusively described, but the present invention is not necessarily limited thereto. The technique of the present disclosure may be applied to an apparatus that acquires three-dimensional OCT data regarding a part or the whole of an eye to be examined. For example, the present disclosure is disclosed for an OCT device that acquires three-dimensional OCT data regarding an anterior segment. The technique of this indication may be applied, and the technique of this indication may be applied with respect to the OCT device which acquires the three-dimensional OCT data regarding each position from an anterior eye part to a fundus.

  Further, in the description of the modification examples shown in FIGS. 8 and 9, the A-scan data based on the measurement light that has passed through the galvanometer mirrors 208a1 and 208a2 has been described as indicating information on the same depth band. Information on different depth zones may be indicated. In this case, the optical path length difference between the reference light and the measurement light passing through the galvanometer mirror 208a1 (hereinafter referred to as the first measurement light), and the measurement light passing through the reference light and the galvanometer mirror 208a2 (hereinafter referred to as the second measurement light). It is sufficient that there is a difference according to the difference in the depth band between the difference in the optical path length between the light and the light. That is, reference optical paths having different optical path lengths may be provided corresponding to the galvano mirrors 208a1 and 208a2, and the optical path length of the measurement optical path passes through the galvano mirror 208a1 and passes through the galvano mirror 208a2. In some cases, they may be different from each other.

  Further, the in-focus positions may be different between the respective measurement lights that have passed through the galvanometer mirrors 208a1 and 208a2. For example, the measurement light passing through one of the two galvanometer mirrors 208a1 and 208a2 is focused on the retina surface (an example of the first in-focus position), and the measurement light passing through the other is more positioned on the choroid side (first 2 may be in focus. With such a configuration, the entire observation range in the retina can be observed with high sensitivity.

  Further, for example, at least one of the scanning speed of the measurement light in the raster scan and the size of the region scanned with the measurement light may be changeable for each raster scan by the control unit 70.

  The higher the scanning speed of the measuring light and the larger the area scanned with the measuring light on the eye to be examined, the more light can be irradiated to the eye while satisfying the light safety. Therefore, for example, when at least one of the scanning speed of the measurement light and the size of the region where the measurement light is scanned is changed, the control unit 70 changes the measurement light according to the amount of change in the scanning speed. The amount of light may be changed. In this case, the control unit 70 may adjust the light amount by controlling the output from the light source. Further, the control unit 70 may adjust the amount of the measurement light irradiated to the eye to be examined by controlling a member provided on the light projection optical path of the measurement light. For example, a fiber attenuator (attenuator) may be provided to control the attenuation amount in the fiber attenuator. In addition, an aperture or filter that can be inserted and removed on the optical path, an aperture that can change the aperture diameter, or the like may be provided, and the amount of light blocked by the aperture or filter may be switched.

  In addition, a scanning range (hereinafter referred to as “first scanning range”) in the measurement light (referred to as “first measurement light”) passing through the galvanometer mirror 208a1 and measurement light (referred to as “second measurement light”). The scanning range (hereinafter referred to as “second scanning range”) in the “light”) may be different from each other.

  The first scanning range is narrower than the second scanning range in at least the main scanning direction, and the A scan data acquisition position interval in the first scanning range is denser than the second scanning range. In addition, the swing angle and driving speed of the galvanometer mirrors 208a1 and 208a2 may be controlled by the control unit 70. For example, the above scanning state may be realized by turning the galvanometer mirror 208a1 with a small swing angle with respect to the galvanometer mirror 208a2 at a low angular velocity.

  In the case where the first scanning range and the second scanning range are different from each other, for example, the first scanning range is a range including a sieve plate (for example, the optic papilla), and the second scanning range is the first scanning range. The first scanning range and the second scanning range may be set by the control unit 70 so that the range includes the range. Thereby, detailed thickness information of the sieve plate and layer thickness information of the fundus around the sieve plate are quickly obtained. That is, information useful for glaucoma diagnosis can be obtained favorably.

  Further, when the first scanning range and the second scanning range are different from each other, the first measurement light and the second measurement light may have different light amounts. For example, the amount of the first measurement light may be reduced with respect to the second measurement light. Thereby, the S / N ratio of the OCT data based on the first measurement light can be increased while satisfying the optical safety.

  Further, the polarization of the measurement light (first measurement light) passing through the galvano mirror 208a1 and the measurement light (second measurement light) passing through the galvano mirror 208a2 may be different from each other. You may have the orthogonal polarization component. And the control part 70 may process the light reception signal from the detector based on 1st measurement light, and the light reception signal from the detector based on 2nd measurement light, and may acquire polarization | polarized-light OCT data. There are various methods for obtaining various information from polarization OCT data such as polarization uniformity (DOPU) tomogram, birefringence (Retardation or Birefringence) tomogram, and polarization axis rotation (Axis-Orientation) tomogram. This is known and may be applied. For example, refer to JP2013-148482A.

  In the said embodiment, OCT1 demonstrated as what is SS-OCT which is 1 type of FD-OCT. However, OCT1 may be applied to other FD-OCTs. For example, OCT1 may be SD-OCT (Spectral domain OCT). When OCT1 is SD-OCT, OCT1 has a light source that emits a light beam with a low coherent length as a light source, and as a detector, an interference signal between the reference light and the return light of the measurement light from the eye to be examined is a wavelength component. It has a spectroscopic detector that detects each time. Then, OCT data of the eye to be examined is obtained based on the interference signal at each wavelength obtained by the spectroscopic detector. Moreover, the technique of this indication may be applied to OCT devices other than FD-OCT (SS-OCT, SD-OCT, etc.).

DESCRIPTION OF SYMBOLS 1 Optical coherence tomometer 70 Control part 75 Monitor 100 Interference optical system 102 Light source 108,208 Scan part 120 Detector E Eye to be examined

Claims (21)

An OCT optical system that irradiates a tissue of a subject's eye with measurement light from a light source and detects interference between the reference light and the measurement light reflected by the tissue with a detector;
One or more galvanometer mirrors that perform reciprocating driving consisting of forward movement and backward movement and scan the measurement light in a predetermined main scanning direction on the eye to be examined are provided as a main scanning optical scanner, and further, the main scanning A sub-scanning optical scanner having a different scanning direction from the scanning optical scanner, and the measurement light is two-dimensionally measured on the eye to be examined based on the operations of the main-scanning optical scanner and the sub-scanning optical scanner. A scanning unit for scanning;
Control means for acquiring A scan data based on a signal output from the detector at a period of at least 300 kHz,
The control means repeatedly scans the measurement light in the main scanning direction twice or more by reciprocating the galvanometer mirror at a constant swing angle, and the time difference at the start timing of each scan is 5 mm. An optical coherence tomography that controls at least the galvanometer mirror so as to have a value of less than a second. The control means repeatedly scans the measurement light on the same scan line by repeatedly reciprocating the galvanometer mirror at the constant swing angle,
A data set composed of a plurality of A scan data is acquired each time the measurement light is scanned one way with respect to the scan line, and a plurality of data sets acquired in time series with respect to one scan line are processed. The optical coherence tomography according to 1.   The optical coherence tomography apparatus according to claim 2, wherein the control unit obtains OCT angiography related to the scan line by processing the plurality of data sets acquired in time series.   The control means repeatedly scans the measurement light with respect to the scan line so that the scanning directions in the respective scans coincide with each other, and the time difference is not less than 2.5 milliseconds and not more than 5 milliseconds. The optical coherence tomometer according to claim 3, wherein the scanning unit is controlled to be.   The control unit scans the measurement light with respect to a plurality of scan lines having different scanning positions in the sub-scanning direction, and three-dimensionally based on the A scan data obtained by scanning the measurement light with respect to the plurality of scan lines. The optical coherence tomography device according to claim 1, which generates OCT data.   The control means scans the measurement light at least in the forward movement of the galvanometer mirror, and controls the scanning unit so that the forward movement per time is performed in a range of 2 milliseconds to 3 milliseconds. The optical coherence tomography according to any one of claims 1 to 5. The scanning unit has one galvanometer mirror as the main scanning optical scanner,
The control means acquires the A scan data in a range of at least 350 kHz to 500 kHz, and the speed of the forward movement in the galvanometer mirror is 1024 points or more by the forward movement per time. The optical coherence tomometer according to claim 6, wherein the optical coherence tomography is controlled within a range that can be acquired. The scanning unit includes at least a first galvanometer mirror and a second galvanometer mirror as the main scanning optical scanner,
7. The optical coherence tomography device according to claim 1, wherein the control unit scans the measurement light in the main scanning direction by driving the first galvanometer mirror and the second galvanometer mirror in combination. .   The first galvanometer mirror and the second galvanometer mirror are a first measurement beam that is a measurement beam that passes through the first galvanometer mirror, and a second measurement beam that is a measurement beam through the second galvanometer mirror, The optical coherence tomometer according to claim 8, wherein the scanning is performed independently of each other on the eye to be examined. A light selection unit that switches measurement light from a light source between a state of selectively guiding one of the first galvanometer mirror and the second galvanometer mirror and a state of selectively guiding the other to the other ,
The optical coherence tomometer according to claim 9, wherein the control unit controls the light selection unit such that the first measurement light and the second measurement light are alternately irradiated to the eye to be examined for each scan line. The control means includes
The second galvanometer mirror is moved forward during the backward movement of the first galvanometer mirror, and the forward movement of the first galvanometer mirror is performed during the backward movement of the second galvanometer mirror. Controlling one galvanometer mirror and the second galvanometer mirror;
Further, scanning of the first measurement light on the eye to be examined is performed based on the forward movement of the first galvanometer mirror, and scanning of the second measurement light on the eye to be examined is based on the forward movement of the second galvanometer mirror. Controlling the light selector to be performed,
The optical coherence tomograph according to claim 10.   The OCT optical system includes the first galvanometer mirror so that information on the same depth band is indicated by A scan data based on the first measurement light and A scan data based on the second measurement light. The optical coherence tomography device according to claim 9, further comprising a corresponding reference optical path and a reference optical path corresponding to the second galvanometer mirror.   The control means is configured such that the first scanning range by the first measuring light is narrower than the second scanning range by the second measuring light at least in the main scanning direction, and the A scan data acquisition position interval is The optical coherence tomography according to any one of claims 9 to 12, wherein a swing angle and a driving speed of the first galvanometer mirror and the second galvanometer mirror are controlled so as to be dense.   The control means sets the first scanning range so as to include the sieve plate of the eye to be examined, and further sets the second scanning range so as to include the first scanning range. Optical coherence tomography as described. The first measurement light and the second measurement light have different polarizations,
The calculation means processes a light reception signal from the detector based on the first measurement light and a light reception signal from the detector based on the second measurement light to obtain polarization OCT data. The optical coherence tomography according to any one of 9 to 14.   The OCT optical system corresponds to the first galvanometer mirror so that information on different depth bands is indicated by the A scan data based on the first measurement light and the A scan data based on the second measurement light. The optical coherence tomography device according to claim 9, further comprising: a reference optical path that corresponds to the second galvanometer mirror.   The first galvanometer mirror and the second galvanometer mirror are arranged in series so that the light scanned by one of the first galvanometer mirror and the second galvanometer mirror is further scanned by the other. The optical coherence tomographic system according to claim 8.   The light according to claim 17, wherein a size of a mirror surface on one of the first galvanometer mirror and the second galvanometer mirror disposed closer to the eye to be examined is larger than a size of the mirror surface on the remaining one. Coherence tomography.   The control means further scans the light scanned by one of the first galvanometer mirror and the second galvanometer mirror with the other, so that the scanning speed in the main scanning direction is changed between the first galvanometer mirror and the first galvanometer mirror. The optical interference according to claim 17 or 18, wherein the first galvanometer mirror and the second galvanometer mirror are synchronously controlled so as to be amplified when only one of the second galvanometer mirror is driven. Tomometer.   The control unit drives one of the first galvanometer mirror and the second galvanometer mirror closer to the subject's eye at a slower turning speed than the remaining one. Optical coherence tomography.   The said control means scans the measurement light on the eye to be examined based on each of the forward movement and the backward movement of the galvanometer mirror, and further acquires A scan data based on each scan. Optical coherence tomography.

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