JP2018023675A - Optical tomographic imaging apparatus - Google Patents

Abstract

An optical tomographic imaging apparatus capable of easily performing alignment while using a non-telecentric optical system when imaging an anterior segment. A light source and light emitted from the light source are divided into measurement light and reference light that irradiate the eye to be examined via a measurement optical system, and the return light of the measurement light and the reference light are combined. An information acquisition unit that acquires information on the tomographic tomography of the eye to be examined, and an optical path length changing unit that changes an optical path length difference between the optical path of the measurement light and the optical path of the reference light, The measurement optical system includes a focusing lens that focuses the measurement light on the eye to be examined. When imaging the anterior eye portion of the eye to be examined, the exit pupil of the measurement optical system is arranged at a finite distance, and the eye to be examined is On the other hand, when the measurement optical system is arranged at a predetermined working distance, the focusing lens and the optical path length changing unit are respectively set to predetermined intervals so that the measurement light is focused on the anterior segment and the anterior segment is in the imaging range. An optical tomographic imaging apparatus arranged at a position. [Selection] Figure 8

Description

  The present invention relates to an optical tomographic imaging apparatus.

  An imaging apparatus (hereinafter referred to as an OCT apparatus) using an optical coherence tomography (hereinafter referred to as OCT) has been developed. In the OCT apparatus, measurement light, which is low-coherent light, is irradiated onto an object, and interference light is obtained by causing scattered / reflected light from the object to interfere with reference light. Then, by analyzing the frequency component of the spectrum of the interference light, it is possible to obtain information relating to the tomography of the object, particularly a high-resolution tomographic image of the object.

  The OCT apparatus is often used for fundus examination as an ophthalmic imaging apparatus. When the OCT apparatus is used for fundus examination, the optical path length changing unit is used to adjust the optical path length difference between the measurement light and the reference light according to the fundus position of the eye to be examined, and a desired depth in the fundus of the eye to be examined. A tomographic image of the position can be acquired.

  The OCT apparatus can also acquire a tomographic image of not only the fundus of the eye to be examined but also the anterior segment. By inserting / removing a predetermined lens into / from the optical path of the measurement light inside or outside the OCT apparatus, the target for obtaining the tomographic image can be switched between the fundus and the anterior segment.

  In the apparatus described in Patent Document 1, a tomographic image of the anterior segment is acquired by mounting a lens outside the OCT apparatus. Here, the tomographic image of the anterior eye part is acquired after the reference mirror and the focusing lens for focusing arranged in the optical path of the reference light are moved to a predetermined position. This solves the difficulty in positioning (alignment) between the OCT apparatus and the eye to be examined when acquiring a tomographic image of the anterior segment.

  As a configuration for acquiring a tomographic image of the anterior segment by the OCT apparatus, the anterior segment is arranged using a telecentric optical system in which the principal ray of the measurement light applied to the anterior segment is parallel to the optical axis of the measurement beam. Optical configurations for scanning are known. Also in the apparatus described in Patent Document 1, a tomographic image of the anterior ocular segment is acquired with the optical system as a telecentric configuration.

JP 2011-147612 A

  On the other hand, the structure which acquires the tomographic image of an anterior eye part using a non-telecentric optical system is also considered. However, when a tomographic image of the anterior segment is acquired using a non-telecentric optical system, the measurement light emitted from the adapter lens to the subject's eye has an angle with respect to the optical axis of the measurement light. For this reason, the range of the anterior segment scanned by the measurement light changes depending on the distance between the adapter lens and the eye to be examined. For example, when the distance between the adapter lens and the eye to be examined is shorter, the measurement light having an angle with respect to the optical axis of the measurement light scans the position of the anterior segment near the center of the adapter lens. On the other hand, when the distance between the adapter lens and the eye to be examined is longer, the measurement light having an angle with respect to the optical axis of the measurement light scans the position of the anterior segment away from the center of the adapter lens. become. Therefore, when imaging a desired range of the anterior segment using a non-telecentric optical system, the alignment between the OCT apparatus and the eye to be examined is important.

  Here, when imaging the anterior ocular segment, the optical path length of the measurement light and the focus position of the measurement light are different from those in the case of imaging the fundus, so the optical path length of the reference light to cause interference with the measurement light or measurement It is necessary to adjust the focus position of the light. Therefore, when imaging the anterior eye part, the alignment between the OCT apparatus and the eye to be examined becomes complicated as the optical path length of the reference light and the focus position of the measurement light are adjusted.

  In contrast, the present invention provides an optical tomographic imaging apparatus that can easily perform alignment while using an optical system having a non-telecentric configuration when imaging an anterior segment.

  In order to solve the above problems, an optical tomographic imaging apparatus according to an embodiment of the present invention includes a light source, measurement light that irradiates the eye to be examined with light emitted from the light source via a measurement optical system, and reference light. And an information acquisition unit that acquires information on a tomogram of the eye to be examined based on interference light obtained by combining the return light of the measurement light and the reference light from the eye to be examined; and An optical path length changing unit that changes an optical path length difference between an optical path of measurement light and an optical path of the reference light, and the measurement optical system includes a focusing lens that focuses the measurement light on the eye to be examined; When imaging the anterior eye part of the eye to be examined, including scanning means for scanning the measurement light on the eye to be examined and imaging part switching means for switching the part of the eye to be examined that is irradiated with the measurement light. The object to be measured is arranged so that the exit pupil of the measurement optical system is arranged at a finite distance. When the imaging part switching unit is disposed between the eye and the scanning unit, and the measurement optical system is disposed at a predetermined working distance with respect to the eye to be examined, the measurement light is transmitted to the anterior eye portion. The focusing lens and the optical path length changing means are respectively arranged at predetermined positions so that the in-focus portion and the anterior eye portion are within the imaging range.

  With the optical tomographic imaging apparatus according to the present invention, alignment can be easily performed while using a non-telecentric optical system when imaging the anterior segment.

1 schematically shows a configuration of an OCT apparatus according to a first embodiment of the present invention. It is a figure for demonstrating the scan of the to-be-examined eye of the x direction. 2 shows examples of an anterior eye image, a fundus two-dimensional image, and a B-scan image according to Example 1. The example of the anterior eye image which concerns on Example 1, the anterior eye part two-dimensional image, and a B scan image is shown. The optical path of the measurement light when the adapter lens is not inserted is shown. The optical path of the measurement light when an adapter lens is inserted is shown. A B-scan image in which the field of view changes according to the working distance is shown. The relationship between a reference optical path length equivalent position and the imaging range of an OCT tomogram is shown. It is a figure for demonstrating the correction method of the optical path length at the time of front-eye part imaging | photography. It is a figure for demonstrating the change of the scanning angle according to a working distance. The structure of the OCT apparatus at the time of imaging a fundus and an anterior segment is shown.

  First, the configuration of the OCT apparatus when imaging the fundus and the configuration of the OCT apparatus when imaging the anterior segment will be described with reference to FIGS. FIG. 11A shows the configuration of the OCT apparatus when imaging the fundus. FIG. 11B shows the configuration of an OCT apparatus that images the anterior eye segment using a telecentric optical system. FIG. 11C shows the configuration of an OCT apparatus that images the anterior eye segment using a non-telecentric optical system. In FIGS. 11A to 11C, components of the OCT apparatus other than the objective lens OL and the adapter lenses AL1 and AL2 are omitted for simplification of description. In FIGS. 11A to 11C, the measurement light transmitted through different regions of the objective lens OL is represented by solid lines and broken lines. In FIGS. 11B and 11C, the adapter lenses AL1 and AL2 are connected to the objective lens OL, but the adapter lens can be connected to the OCT apparatus by any configuration.

  When acquiring a tomographic image of the fundus, as shown in FIG. 11A, the measurement light transmitted through the objective lens OL of the OCT apparatus enters the pupil of the eye E and converges on the fundus of the eye E. Reflected or scattered. On the other hand, when imaging the anterior segment of the eye E, adapter lenses AL1 and AL2 are inserted between the objective lens OL and the eye E as shown in FIGS. Is done. In this case, the measurement light passes through the objective lens OL, and then converges at the anterior eye portion of the eye E through the adapter lenses AL1 and AL2. Thereafter, the measurement light is reflected or scattered by the anterior segment of the eye E.

  Here, when the anterior segment of the eye E is imaged using a telecentric optical system, measurement light enters the adapter lens AL1 from the objective lens OL. The measurement light transmitted through the adapter lens AL1 is irradiated to the eye E as a light beam whose principal ray is parallel to the optical axis of the measurement light, and converges and is reflected or scattered by the anterior eye portion. In this case, as shown in FIG. 11 (b), the adapter lens AL1 is such that all of the light beam transmitted through the objective lens OL is incident on the adapter lens AL1 and the measurement light is irradiated to a desired range of the anterior segment. Need to be configured larger.

  On the other hand, the structure which images the anterior eye part of the eye E to be examined using a non-telecentric optical system is also considered. In this case, as shown in FIG. 11 (c), the measurement light incident on the adapter lens AL2 from the objective lens OL passes through the adapter lens AL2, and then is a light beam having an angle with respect to the optical axis of the measurement light. The anterior eye part of the eye E is irradiated, converged at the anterior eye part, and reflected or scattered.

  In such a configuration, since the adapter lens AL2 is disposed at the front focal position (pivot position) of the objective lens OL, it is not necessary to increase the size of the adapter lens AL2. Therefore, in the OCT apparatus using the non-telecentric optical system, the size of the adapter lens AL2 can be made compact compared to the case where the telecentric optical system is used.

  In the following, an exemplary embodiment for carrying out the present invention assumes a non-telecentric optical system as shown in FIG. The following examples will be described in detail with reference to the drawings. However, dimensions, materials, shapes, and relative positions of components described in the following embodiments are arbitrary and can be changed according to the configuration of the apparatus to which the present invention is applied or various conditions. Also, in the drawings, the same reference numerals are used between the drawings to indicate the same or functionally similar elements.

[Example 1]
(Schematic configuration of the device)
A schematic configuration of an OCT apparatus 1 that is an example of an optical tomographic imaging apparatus according to Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 shows a schematic configuration of an OCT apparatus 1 according to the present embodiment.

  The OCT apparatus 1 is provided with an optical head 900, a control unit 170 (information acquisition unit), and a display unit 190. The optical head 900 is configured as a measurement optical system for capturing an anterior eye image of the eye 100 to be examined and a two-dimensional image and tomographic image of the fundus or anterior eye portion. The control unit 170 performs drive control of each optical element in the optical head 900, processing of signals output from the optical head 900, generation of an image, and the like. The display unit 190 displays images and information output from the control unit 170. The control unit 170 can be configured using any computer, and may be configured as a computer for the OCT apparatus 1 or may be configured using a general general-purpose computer. In FIG. 1, the control unit 170 is illustrated as a separate body from the optical head 900, but the control unit may be configured integrally with the optical head 900. The display unit 190 can be configured by an arbitrary monitor. The display unit 190 may be integrated with the control unit 170 and the optical head 900.

(Optical system of the optical head 900)
The configuration of the optical system of the optical head 900 according to this embodiment will be described with reference to FIG. In the optical head 900, an objective lens 101-1 is provided to face the eye 100 to be inspected. In addition, an adapter lens 105 that can be inserted and removed is provided as an imaging region switching unit between the eye 100 to be examined and the objective lens 101-1. The OCT apparatus 1 removes the adapter lens 105 from between the objective lens 101-1 and the eye 100 when imaging the fundus of the eye 100, and the adapter lens when imaging the anterior eye portion of the eye 100. 105 is inserted.

  Inside the optical head 900, a first dichroic mirror 102, a second dichroic mirror 103, and a third dichroic mirror 104 are arranged as optical path separating means. The objective lens 101-1 is disposed facing the eye 100, the first dichroic mirror 102 is disposed on the optical axis of the reflected light from the eye 100, and the optical axis of the reflected light of the first dichroic mirror 102 is disposed. A second dichroic mirror 103 is disposed.

  The first dichroic mirror 102 separates the optical path of the reflected light from the eye 100 so that the transmitted light is directed to the anterior eye observation optical path L3 and the reflected light is directed to the second dichroic mirror 103. The second dichroic mirror 103 has a wavelength of the optical path of the reflected light of the first dichroic mirror 102 so that the transmitted light is directed to the measurement optical path L1 of the OCT optical system and the reflected light is directed to the optical path L2 for two-dimensional observation and fixation lamp. Separate by band. As will be described later, the third dichroic mirror 104 is disposed in the optical path L2, and further separates the optical path L2 into a two-dimensional observation optical path and a fixation lamp optical path for each wavelength band.

  The optical path L2 is provided with an X scanner 117-1 and a Y scanner 117-2 that constitute scanning means 117 described later. The OCT apparatus 1 can obtain a two-dimensional image of the fundus by scanning illumination light on the fundus using the X scanner 117-1 and the Y scanner 117-2 when photographing the fundus of the eye 100 to be examined. In addition, when the adapter lens 105 is inserted, the OCT apparatus 1 scans illumination light on the anterior segment using the X scanner 117-1 and the Y scanner 117-2, so that the anterior segment A two-dimensional image can be obtained.

  In the optical path L2, in order from the second dichroic mirror 103, the lens 101-2, the X scanner 117-1, the Y scanner 117-2, the focusing lens 112, the optical path separation member 118, the lens 113-1, and the third dichroic mirror. 104 is arranged. The optical path L2 is separated by the third dichroic mirror 104 into an optical path to the light source 114 for two-dimensional observation and an optical path to the fixation lamp 119 for each wavelength band.

  The light source 114 generates light having a wavelength of 780 nm, and the light emitted from the light source 114 is reflected by the third dichroic mirror 104 and travels toward the optical path L2. The fixation lamp 119 is used to promote fixation in an arbitrary direction / position with respect to the eye 100 to be inspected, and is composed of, for example, a laser or LED (Light Emitting Diode) that emits a wavelength in the visible range. The light emitted from the fixation lamp 119 passes through the third dichroic mirror 104 and travels to the optical path L2. The light source 114 and the fixation lamp 119 are arranged so that the light emitted from the light source 114 is transmitted through the third dichroic mirror 104 and the light emitted from the fixation lamp 119 is reflected by the third dichroic mirror 104. May be.

  The optical path separating member 118 can be configured by a perforated mirror or a prism on which a hollow mirror is deposited, and an optical path through which illumination light from the light source 114 or light from the fixation lamp 119 propagates and illumination from the fundus Separates the optical path through which the return light travels. Light from the light source 114 and the fixation lamp 119 passes through the optical path separating member 118 and reaches the scanning unit 117 configured by the X scanner 117-1 and the Y scanner 117-2 via the focusing lens 112.

  The focusing lens 112 is a lens for adjusting the focus of the fixation lamp 119, the single detector 116 for two-dimensional observation, and the light source 114. The focusing lens 112 can be driven by a motor (not shown), and the motor control unit 172 included in the control unit 170 controls the motor (not shown) to adjust the focus of light from the light source 114 and the like. Therefore, it is driven in the optical axis direction (arrow direction in the figure). The focusing lens 112 can focus the light from the light source 114 or the like on the eye 100 by being driven in the optical axis direction.

  The X scanner 117-1 and the Y scanner 117-2 constitute scanning means 117 used for scanning illumination light emitted from the light source 114 on the fundus or anterior eye portion of the eye 100 to be examined. The X scanner 117-1 is configured by a polygon mirror in order to scan the illumination light at high speed in the x direction. In addition, the X scanner 117-1 may be composed of a resonance type mirror. The Y scanner 117-2 is configured using a deflection mirror such as a galvanometer mirror in order to scan the illumination light in the y direction. The driving of the X scanner 117-1 and the Y scanner 117-2 is controlled by the drive control unit 172 of the control unit 170. Each direction of the x direction and the y direction is a direction orthogonal to the axial direction of the eye 100 to be examined and is a direction orthogonal to each other.

  In FIG. 1, the optical path between the X scanner 117-1 and the pinhole 115, the light source 114, and the fixation lamp 119, which will be described later, is configured in the plane of the paper, but is actually configured in the direction perpendicular to the plane of the paper. ing. When the configuration by these optical paths becomes large in the direction perpendicular to the paper surface, the optical path may be bent by a mirror (not shown). The lens 101-2 is disposed with the vicinity of the center position of the X scanner 117-1 and the Y scanner 117-2 as a focal position.

  The fixation lamp 119 is controlled to be turned on by the control unit 170 in accordance with the driving of the X scanner 117-1 and the Y scanner 117-2, thereby fixing the fixation eye 119 in an arbitrary direction and position. Can be urged.

  On the optical path of the reflected light of the optical path separating member 118, a lens 113-2, a pinhole 115, and a single detector 116 are arranged. When the adapter lens 105 is not inserted, the pinhole 115 is disposed at a substantially conjugate position with the fundus of the eye 100 to be examined, and the confocal optical system is configured by the top of the fundus and the pinhole 115. When the adapter lens 105 is inserted, the pinhole 115 is disposed at a position substantially conjugate with the anterior eye portion of the eye 100 to be examined, and the confocal optical system is configured by the anterior eye portion and the pinhole 115. . Illumination light from the light source 114 that scans the fundus or anterior segment is scattered and reflected by the fundus or anterior segment. With respect to the scattered and reflected light, only necessary light is transmitted through the pinhole 115 and received by the single detector 116. The single detector 116 is composed of an APD (avalanche photodiode) and receives return light of irradiation light from the eye 100 to be examined. Note that components such as the third dichroic mirror 104 may be arranged on the optical path of the reflected light of the optical path separating member 118, and the pinhole 115 etc. may be arranged on the optical path of the transmitted light of the optical path separating member 118.

  The control unit 170 of the OCT apparatus 1 can acquire information on the fundus or anterior segment of the eye 100 to be detected from the light detected by the single detector 116, and can form a two-dimensional image of the fundus or anterior segment.

  The anterior eye observation optical path L3 is an optical path of light transmitted through the first dichroic mirror 102. A lens 141 and an anterior eye observation CCD 142 are arranged in this order from the first dichroic mirror 102 on the anterior eye observation optical path L3. The CCD 142 has sensitivity in the wavelength of light emitted from an unillustrated anterior eye observation illumination light source, specifically around 970 nm, and detects the return light of the anterior eye observation illumination light from the eye 100 to be examined.

  The control unit 170 of the OCT apparatus 1 can acquire information on the anterior segment of the eye 100 from the light detected by the CCD 142 and form an anterior eye image. Information on the anterior segment acquired using the CCD 142 can be used for alignment (alignment) of the optical head 900 with respect to the eye 100 to be examined.

  As described above, the measurement optical path L1 forms a part of the OCT optical system, and is used to capture a tomographic image of the fundus of the eye 100 when the adapter lens 105 is not inserted. Further, the measurement optical path L1 is used to capture a tomographic image of the anterior segment of the eye 100 when the adapter lens 105 is inserted. More specifically, the measurement optical path L1 is used to obtain an interference signal for forming a tomographic image of the fundus or anterior segment of the eye 100 to be examined.

  In the measurement optical path L1, a lens 101-3, a mirror 121, an OCTX scanner 122-1, an OCTY scanner 122-2, an OCT focusing lens 123, a lens 124, and a fiber end 126 are arranged in this order from the second dichroic mirror 103. . These components constitute a part of an OCT measurement optical system that irradiates the eye 100 with OCT measurement light described later.

  The fiber end 126 allows measurement light to enter the measurement optical path L1. The fiber end 126 can also be grasped as a light source of measurement light in this embodiment. The fiber end 126 has an optical conjugate relationship with the fundus when the adapter lens 105 is not inserted, and has an optical conjugate relationship with the anterior segment when the adapter lens 105 is inserted.

  The OCT focusing lens 123 is a lens for adjusting the focusing of the measurement light to the fundus or anterior eye portion. The OCT focusing lens 123 can be driven by a motor (not shown), and the motor (not shown) is controlled by a drive control unit 172 included in the control unit 170, so that the light for adjusting the focus of measurement light can be obtained. Driven in the axial direction (arrow direction in the figure). The OCT focusing lens 123 can focus the measurement light on the eye 100 by being driven in the optical axis direction. The focus adjustment of the measurement light is performed so that the light emitted from the fiber end 126 grasped as the light source of the measurement light is imaged on the fundus or the anterior eye part. However, when acquiring a tomographic image of the anterior segment, the OCT focusing lens 123 is disposed at a predetermined position as will be described later.

  The OCTX scanner 122-1 and the OCTY scanner 122-2 constitute an OCT scanning unit 122, and scans the measurement light on the fundus or anterior eye part of the eye 100 to be examined. The OCTX scanner 122-1 and the OCTY scanner 122-2 can be composed of an arbitrary deflection mirror such as a galvanometer mirror. The driving of the OCTX scanner 122-1 and the OCTY scanner 122-2 can be controlled by the drive control unit 172 of the control unit 170. Further, the OCT scanning unit 122 may be configured by a single deflection mirror capable of two-dimensional scanning of the measurement light. In this case, the drive control unit 172 controls the driving of the deflection mirror. In FIG. 1, the optical path between the OCTX scanner 122-1 and the OCTY scanner 122-2 is configured in the plane of the paper, but is actually configured in the direction perpendicular to the plane of the paper. The extending direction of the optical path between the OCTX scanner 122-1 and the OCTY scanner 122-2 can be an arbitrary direction according to a desired configuration.

  Next, the configuration of the optical system from the light source 130 to the fiber end 126, the reference optical system, and the spectroscope 180 will be described.

  In this embodiment, an SLD (Super Luminescent Diode), which is a typical low-coherent light source, is used as the light source 130, the center wavelength is 855 nm, and the wavelength bandwidth is about 100 nm. Here, the bandwidth is an important parameter because it affects the resolution of the obtained tomographic image in the optical axis direction. Further, although the SLD is selected here as the type of the light source 130, any type of light source that can emit low-coherent light may be used. Near-infrared light can be used as the center wavelength of the light source 130 in view of measuring the eye. Further, when the NA (numerical aperture) is the same, it affects the lateral resolution of the tomographic image from which the center wavelength is obtained. Therefore, the light source 130 having a center wavelength as short as possible can be used. For both reasons, the center wavelength was set to 855 nm in this example.

  The light emitted from the light source 130 passes through the optical fiber 125-1 and reaches the optical coupler 125. The single mode optical fibers 125-1 to 12-4 are connected to the optical coupler 125. The light reaching the optical coupler 125 is divided into measurement light and reference light here, and the measurement light is guided to the measurement optical path L1 via the optical fiber 125-2, and the reference light is guided to the reference optical path L4 via the optical fiber 125-3. It is burned. The optical coupler 125 divides the light emitted from the light source 130 into measurement light and reference light, and combines an interference unit that obtains interference light by combining the return light of the measurement light from the eye 100 and the reference light. Configure.

  The light incident on the optical fiber 125-2 reaches the fiber end 126 described above. The measurement light is irradiated to the fundus or anterior eye portion of the eye 100 to be observed through the measurement optical path L1, and reaches the optical coupler 125 through the same optical path due to reflection or scattering by the retina or cornea. Here, the optical path from the optical coupler 125 to the fiber end 126, the measurement optical path L1, and the optical path from the second dichroic mirror 103 to the eye 100 constitute an OCT measurement optical path, and the optical member arranged in the OCT measurement optical path is OCT. Configure the measurement optical system.

  In the reference optical path L4, a lens 151, a dispersion compensation glass 152, and a reference mirror 153 are arranged in order from the exit end of the optical fiber 125-3. Here, the optical member arranged in the reference optical path L4 constitutes an OCT reference optical system.

  The reference light emitted from the exit end of the optical fiber 125-3 reaches the reference mirror 153 through the lens 151 and the dispersion compensation glass 152 and is reflected. The dispersion compensation glass 152 is inserted into the reference optical path L4 in order to match the dispersion of the measurement light and the reference light. The reference light reflected by the reference mirror 153 returns along the same optical path and reaches the optical coupler 125. The reference mirror 153 is held by an unillustrated motor and drive mechanism controlled by the drive control unit 172 so as to be adjustable in the optical axis direction (arrow direction in the drawing). For this reason, the reference mirror 153 constitutes an optical path length changing unit that can change the optical path length of the reference light by being driven in the optical axis direction.

  As will be described later, the dispersion of the adapter lens 105 is substantially equal to the dispersion from the anterior eye portion of the eye 100 to the fundus. Therefore, it is not necessary to remove the dispersion compensation glass 152 from the reference optical path L4 even during anterior segment imaging, and it is not necessary to insert a new dispersion compensation glass.

  In the optical coupler 125, the return light of the measurement light from the eye 100 and the reference light reflected from the reference mirror 153 are combined to become interference light. Here, the return light of the measurement light and the reference light cause interference when the optical path length of the return light and the optical path length of the reference light are substantially the same. In the OCT apparatus 1, by driving the reference mirror 153 in the optical axis direction, the optical path length of the reference light can be matched to the optical path length of the return light that varies depending on the eye 100 to be examined. The interference light is guided to the spectrometer 180 through the optical fiber 125-4.

  The spectroscope 180 constitutes a detection unit that receives interference light between the return light of the measurement light from the eye 100 and the reference light. The spectroscope 180 is provided with lenses 181 and 183, a diffraction grating 182, and a line sensor 184. The interference light emitted from the optical fiber 125-4 becomes substantially parallel light via the lens 181, and then is split by the diffraction grating 182 and imaged on the line sensor 184 by the lens 183. An interference signal generated based on the interference light detected by the line sensor 184 as a detector is output as an output signal to the arithmetic processing unit 171 of the control unit 170. The arithmetic processing unit 171 performs processing such as fast Fourier transform (FFT) on the interference signal output from the line sensor 184, and constructs and acquires information on the eye 100 as a tomographic image.

  Next, the control unit 170 will be described. The control unit 170 configures an information acquisition unit that controls each component of the optical head 900, processes a signal output from the optical head 900, and forms an image. The control unit 170 is provided with an arithmetic processing unit 171, a drive control unit 172, a storage unit 173, and an input unit 174. The control unit 170 is connected to the optical head 900 and the display unit 190 so as to be electrically communicable.

  The arithmetic processing unit 171 can receive signals output from the single detector 116 of the optical head 900, the CCD 142, and the line sensor 184 of the spectroscope 180, and process them to form various images. Specifically, the arithmetic processing unit 171 processes a signal output from the single detector 116 to form a two-dimensional image (front image) of the fundus or anterior eye part of the eye 100 to be examined, and a signal output from the CCD 142. And an anterior eye image of the eye 100 to be examined is formed. In addition, the arithmetic processing unit 171 performs processing such as fast Fourier transform (FFT) on the interference signal output from the line sensor 184, and uses information related to luminance distribution (light intensity information) included in the interference signal. A tomographic image of the fundus or anterior segment is formed. The arithmetic processing unit 171 can send the formed various images to the display unit 190 and cause the display unit 190 to display these images and the like.

  The drive control unit 172 controls driving of the focusing lens 112, the scanning unit 117, the OCT scanning unit 122, the OCT focusing lens 123, and the reference mirror 153 of the optical head 900. In addition, the drive control unit 172 performs lighting control of the fixation lamp 119. Further, the drive control unit 172 can control a drive mechanism (not shown) of the adapter lens 105 to be described later to control insertion / removal of the adapter lens 105 with respect to the optical path. Note that the examiner may insert or remove the adapter lens 105.

  The arithmetic processing unit 171 and the drive control unit 172 can be realized by an arithmetic processing device such as a CPU of the control unit 170, for example, each can be realized as one module. Further, the arithmetic processing unit 171 and the drive control unit 172 may be realized by a plurality of modules, respectively, or may be realized by a single module.

  The storage unit 173 stores an arbitrary program executed by the control unit 170, control information of various components such as the OCT scanning unit 122 in the optical head 900, an image of the formed eye 100, information on the subject, and the like. Can do. The storage unit 173 can be configured by any storage unit. The input unit 174 can accept an examiner's input to the control unit 170. The input unit 174 can be configured by any input means, and can include, for example, a mouse and a keyboard.

(Adapter lens)
In this embodiment, when photographing the anterior segment, an adapter lens 105 that can be inserted and removed is inserted between the objective lens 101-1 and the eye 100 to be examined. The adapter lens 105 is provided at a position facing the eye to be examined 100 in the optical head 900 as an imaging part switching means for switching an imaging part between the fundus and the anterior eye part of the eye 100 to be examined. The adapter lens 105 may be included in the housing of the optical head 900, or may be configured to be attached to the housing outside the housing. Further, the dispersion amount of the adapter lens 105 is configured to be substantially equal to the dispersion from the anterior eye portion of the eye 100 to the fundus so that the dispersion of the OCT measurement optical system is not changed by the insertion / removal of the adapter lens 105. .

  The adapter lens 105 constitutes an optical member that is inserted between the OCT scanning unit 122 and the eye 100 to switch the tomographic image acquisition position (measurement site) between the fundus and the anterior segment of the eye 100 to be examined. The adapter lens 105 is disposed at the focal position of the objective lens 101-1 when imaging the anterior segment and at a position optically conjugate with the OCT scanning unit 122. In this embodiment, the adapter lens 105 is inserted between the eye 100 to be examined and the objective lens 101-1 due to the ease of configuration or the like, but the optical path between the eye 100 to be examined and the OCT scanning unit 122 may be used. Can be inserted at any position.

  Further, the insertion of the adapter lens 105 into the optical path is controlled by the drive control unit 172 in accordance with a measurement site switching instruction for acquiring a tomographic image received by the control unit 170 via the input unit 174. it can. On the other hand, the adapter lens 105 can be manually inserted, the insertion of the adapter lens 105 can be detected using an arbitrary sensor or the like, and the control unit 170 can execute various controls according to the switching of the measurement site. .

  Considering that the conjugate position of the fiber end 126 is switched from the fundus of the eye 100 to the anterior eye portion by inserting the adapter lens 105, the adapter lens 105 can be a convex lens.

Further, the thickness of the adapter lens 105 can be determined by considering the group velocity GD when light passes from the anterior segment of the eye 100 to the fundus. The group velocity GD is expressed by the following formula 1.
GD = dng / dλ = −λ × d ² n / dλ ² (Formula 1)
Here, ng = n−λ × dn / dλ, where λ is the center wavelength of the light source 130, dng / dλ is the wavelength derivative of the group refractive index ng, and d ² n / dλ ² is the second order of the wavelength of the refractive index n. Dn / dλ represents the wavelength differentiation of the refractive index n.

  The group velocity GD of the medium in the eye 100 to be examined is obtained by Equation 1, and the product (GD × L) of the medium in the eye 100 with the thickness L in the optical axis direction (GD × L) is approximately the same between the eye 100 and the adapter lens 105. Thus, the glass material and thickness of the adapter lens 105 are determined. Thereby, the OCT apparatus 1 can cancel the dispersion of the light generated in the OCT measurement optical system, and can obtain a clear tomographic image without bleeding. Furthermore, it is possible to eliminate the need for adjustment of dispersion associated with switching between photographing of the fundus and the anterior segment. When dispersion compensation is performed by signal processing, signal processing for dispersion compensation can be simplified.

  Further, since the distance between the optical head 900 and the subject eye 100 changes from the distance when the fundus is imaged due to the insertion of the adapter lens 105 and the change of the measurement site of the subject eye 100, the optical path length difference between the measurement light and the reference light is different. change. Therefore, as described later, in this embodiment, the drive control unit 172 moves the position of the reference mirror 153 in the optical axis direction to a predetermined position in accordance with the insertion / removal of the adapter lens 105. Similarly, the focus position of the measurement light also changes in accordance with the change in the optical path length of the measurement light and the change in the measurement site of the eye 100 to be examined. Therefore, in this embodiment, the position of the OCT focusing lens 123 in the optical axis direction is also moved to a predetermined position by the drive control unit 172 in accordance with the insertion / removal of the adapter lens 105.

(Tomographic imaging method)
Hereinafter, a tomographic image capturing method using the OCT apparatus 1 according to the present embodiment will be described with reference to FIGS. The OCT apparatus 1 can capture a tomographic image of a desired site in the fundus or anterior segment of the eye 100 by controlling the OCT scanning unit 122 configured by the OCTX scanner 122-1 and the OCTY scanner 122-2. it can.

  By a series of operations of the above-described OCT optical system, the OCT apparatus 1 can acquire information on a tomogram at a certain point of the eye 100 to be examined. In this way, acquiring information related to the tomography in the depth direction of the eye 100 to be examined is referred to as an A scan. Further, in the OCT apparatus 1, information on a two-dimensional tomographic image and a three-dimensional tomographic image of the eye to be examined 100 can be acquired by scanning the eye to be examined 100 with measurement light by the OCT scanning unit 122.

  Here, scanning the eye 100 with measurement light in a direction in which information about the tomography of the eye 100 to be examined in a direction orthogonal to the A-scan direction, that is, information on a two-dimensional tomographic image, is called B scan. Furthermore, scanning the eye 100 with measurement light in a direction orthogonal to both the scanning directions of the A scan and the B scan is called a C scan. In particular, when two-dimensional raster scanning is performed on the eye 100 when acquiring information of a three-dimensional tomographic image, the direction in which scanning is performed at high speed is referred to as the B-scan direction, and is orthogonal to the B-scan direction and scanned at low speed. The direction in which is performed is referred to as the C scan direction.

  FIG. 2 shows a state in which the eye 100 is irradiated with the measurement light 201 and the fundus 202 is scanned in the x direction with the measurement light 201 (B scan) when the fundus 202 of the eye 100 is imaged. . In FIG. 2, the light beam moved in the x direction is indicated by a broken line, and the one-point difference line indicates the principal ray of each light beam. The line sensor 184 acquires information from the imaging range in the x direction on the fundus 202 by a predetermined number of times of imaging (the number of A scans).

  An arithmetic processing unit 171 performs signal processing such as wave number conversion, dispersion compensation calculation, and fast Fourier transform (FFT) on a luminance distribution signal on the line sensor 184 obtained at a certain position in the x direction. In order to show the linear luminance distribution obtained by the signal processing on the monitor, the image converted to density or color information is called an A-scan image. A two-dimensional image in which a plurality of A-scan images are arranged is called a B-scan image.

  The OCT apparatus 1 captures a plurality of A scan images for constructing one B scan image, and then moves the scan position in the y direction and scans again in the x direction (B scan). A B-scan image can be obtained. The arithmetic processing unit 171 further executes processing such as brightness adjustment on the B-scan image, and displays the processed image on the screen of the display unit 190.

  By displaying a plurality of B-scan images or a three-dimensional tomographic image constructed from a plurality of B-scan images on the display unit 190, the examiner can use these images for diagnosis of the eye 100 to be examined. The above-described method for constructing a tomographic image is the same as that for constructing a tomographic image of the anterior segment of the eye 100 to be examined.

  FIG. 3 shows an image displayed on the display screen 200 of the display unit 190 at the time of fundus photographing in which the adapter lens 105 is not inserted between the eye 100 to be examined and the objective lens 101-1. FIG. 4 shows an image displayed on the display screen 200 at the time of photographing the anterior segment where the adapter lens 105 is inserted between the eye 100 to be examined and the objective lens 101-1. 3 and 4, a broken line shown in the display area 210 indicates an index for alignment between the eye 100 to be examined and the optical head 900 in the xy direction, and a dotted line shown in the display area 211 indicates a tomographic image shown in the display area 212. The index of the position to acquire is shown. In FIG. 4, an alignment reference line 212-1 for photographing the anterior segment is indicated by a broken line in the display area 212.

  At the time of fundus photographing, as shown in FIG. 3, an anterior eye image is displayed in the display area 210, a two-dimensional image of the fundus 202 is displayed in the display area 211, and a B scan image that is a tomographic image of the fundus 202 is displayed in the display area 212. The anterior eye image displayed in the display area 210 is an image formed by the processing unit 171 processing the output signal from the CCD 142. The two-dimensional image of the fundus 202 displayed in the display area 211 is an image formed by the arithmetic processing unit 171 processing the output signal of the single detector 116. A tomographic image of the fundus 202 displayed in the display area 212 is an image constructed by processing the output signal from the line sensor 184 by the arithmetic processing unit 171.

  On the other hand, at the time of photographing the anterior segment, as shown in FIG. 4, the two-dimensional image of the anterior segment in the display area 210, the two-dimensional image of the anterior segment in the display area 211, and the tomogram of the anterior segment in the display area 212. A B-scan image that is an image is displayed. Both the two-dimensional images of the anterior segment displayed in the display areas 210 and 211 are images formed by the processing unit 171 processing the output of the single detector 116. The tomographic image of the anterior segment displayed in the display area 212 is an image constructed by processing the output signal from the line sensor 184 by the arithmetic processing unit 171. At the time of photographing the anterior segment, an alignment reference line 212-1 described later is displayed in advance in the display area 212. The display area 210 may display an image formed by processing an output signal from the CCD 142.

(Alignment during anterior segment imaging)
Hereinafter, with reference to FIG. 5 to FIG. 8, alignment at the time of photographing the anterior segment will be described. FIG. 5 shows an optical path of the measurement light 201 at the time of fundus photographing in which the adapter lens 105 is not inserted between the eye 100 to be examined and the objective lens 101-1. 6A and 6B show the optical path of the measurement light 201 at the time of photographing the anterior segment in which the adapter lens 105 is inserted between the eye 100 to be examined and the objective lens 101-1. In FIGS. 5 to 6B, the principal ray of the measurement light 201 is indicated by a one-dotted line. Further, for the sake of explanation, principal rays 501, 601 and 602 of the measurement light 201 emitted from the objective lens 101-1 with the same angle with respect to the optical axis of the measurement light 201 are shown. Although the adapter lens 105 is shown in FIG. 6 as not being connected to the objective lens 101-1, the adapter lens 105 is included in the optical head 900 as described above, and when the optical head 900 is driven. Works in conjunction with the objective lens 101-1.

  When imaging the fundus 202 of the eye 100, as shown in FIG. 5, the pupil of the eye 100 is arranged at the exit pupil position (pupil position) of the optical head 900 constituting the measurement optical system. The optical head 900 is aligned with respect to the eye 100 to be examined. Here, the position of the exit pupil (pupil position) of the optical head 90 is the position where the principal rays of the measurement light 201 intersect when viewed from the eye 100 to be examined, and the pupil positions are the OCTX scanner 122-1 and the OCTY scanner 122-. This is the optical conjugate position of the center point of 2. With such an arrangement, the measurement light 201 scanned by the OCT scanning unit 122 reaches the fundus 202 of the eye 100 to be examined.

  Here, the alignment of the optical head 900 is performed by the examiner appropriately driving the optical head 900 in the three axial directions of the x direction, the y direction, and the z direction using a driving device such as a stage (not shown). . The alignment of the optical head 900 may be performed by the drive control unit 172 of the control unit 170 controlling the drive device of the optical head 900 based on the acquired anterior eye image or the like.

  When imaging the anterior segment of the eye 100 to be examined, the adapter lens 105 is disposed at the pupil position of the optical head 900 excluding the adapter lens 105 as shown in FIGS. With this arrangement, the exit pupil of the optical head 900 is placed at a finite distance, and the principal ray of the measurement light 201 that scans the anterior segment is not parallel to the optical axis. The optical path for scanning has a non-telecentric configuration. On the other hand, in the conventional OCT apparatus, since the anterior eye part is imaged using a telecentric optical system, the principal ray of the measurement light emitted to the anterior eye part is parallel to the optical axis, so that the exit pupil is infinite. It will be placed at a far point. In the configuration of this embodiment, the adapter lens 105 is disposed at the pupil position where the principal rays of the measurement light 201 intersect, so that the adapter lens 105 can be made more compact than the adapter lens in the conventional telecentric configuration.

  Further, in this configuration, a distance corresponding to the rear focal length of the adapter lens from the front focal position of the objective lens to the adapter lens, which is required between the objective lens and the adapter lens in the conventional telecentric configuration, is not necessary. . Therefore, in the configuration of the adapter lens 105 according to the present embodiment, the distance between the objective lens 101-1 and the eye 100 to be examined can be shortened at the time of photographing the anterior segment as compared with the conventional telecentric configuration. Therefore, in the alignment at the time of anterior segment imaging, the movable range in which the optical head 900 can be driven in the z direction with respect to the subject eye 100 can be widened so that the adapter lens 105 does not contact the subject eye 100. . Therefore, the operability of the OCT apparatus 1 at the time of photographing the anterior segment can be improved with this configuration. Note that these effects can be similarly achieved even when the adapter lens 105 is disposed between the objective lens 101-1 and the OCT scanning unit 122.

  On the other hand, when a tomographic image of the anterior segment is acquired with the configuration according to the present embodiment, the scan range of the eye 100 changes according to the working distance of the optical head 900 with respect to the eye 100. Here, the working distance refers to the distance between the optical elements facing the eye 100. In other words, the distance between the eye 100 and the component closest to the eye 100 in the optical system reaching the eye 100. Say. In the configuration according to the present embodiment when imaging the anterior eye portion of the eye 100 to be examined, the distance between the eye 100 to be examined and the adapter lens 105 is the working distance.

  FIG. 6A shows an optical path of the measurement light 201 at the time of photographing the anterior segment when the optical head 900 is arranged at a position separated from the eye 100 by the working distance WD1. FIG. 6B shows an optical path of the measurement light 201 at the time of photographing the anterior segment when the optical head 900 is disposed at a position separated from the eye 100 by a working distance WD2 longer than the working distance WD1. . FIGS. 7A and 7B show B-scan images captured in the arrangement of the optical head 900 shown in FIGS. 6A and 6B, respectively.

  Referring to FIG. 6A, when the optical head 900 is disposed at the working distance WD1, the principal ray 601 of the measuring light 201 having an angle with respect to the optical axis is near the peripheral edge of the cornea of the eye 100 to be examined. Has reached. On the other hand, referring to FIG. 6B, when the optical head 900 is disposed at a longer working distance WD2, the principal ray 602 of the measurement light 201 having the same angle as the principal ray 601 with respect to the optical axis. Has reached the sclera beyond the peripheral edge of the cornea of the eye 100 to be examined. Therefore, when the optical head 900 is arranged at a longer working distance, the measurement light 201 having an angle in the x direction with respect to the optical axis reaches the position of the eye 100 to be examined further away from the optical axis in the x direction. I understand that As described above, in this configuration, when acquiring a tomographic image of the anterior segment, the optical head 900 for the eye 100 to be examined is obtained even when the OCT scanning unit 122 of the measurement light 201 is driven in the same angular range. The scan range of the eye 100 changes according to the working distance.

  When the working distance of the optical head 900 with respect to the eye 100 changes, as shown in FIGS. 7A and 7B, the anterior eye displayed in the scan range of the eye 100, that is, the display area 211 of the display screen 200. This changes the field of view of the B scan image. Therefore, when analyzing the B-scan image of the anterior segment and obtaining the distances d1, d2, etc. between two points in the B-scan image such as the width of the crystalline lens, this is due to the difference from the assumed field of view. Accurate distance measurement may not be possible. Therefore, it is important to accurately determine the working distance of the optical head 900 with respect to the eye 100 during imaging of the anterior segment. Since the change in the field due to the change in the scan range changes in relation to the scanning by the OCT scanning unit 122, a change occurs in the field in the z direction (depth direction) determined according to the sampling number of the interference signal. Absent.

  In this embodiment, in order to accurately determine the working distance, the working distance is determined by performing alignment (alignment) between the optical head 900 and the eye 100 using the tomographic image acquired by the OCT apparatus 1. Hereinafter, in the OCT apparatus 1 according to the present embodiment, the alignment of the optical head 900 during imaging of the anterior segment of the eye 100 to be examined will be described.

  In the present embodiment, in the alignment at the time of imaging the anterior segment of the eye 100 to be examined, the reference optical path length is first adjusted to a predetermined optical path length. Specifically, the position of the reference mirror 153 in the optical axis direction by the drive control unit 172 is determined in accordance with a predetermined working distance corresponding to an image field where accurate distance measurement can be performed (predetermined position (predetermined) To the position).

  The alignment during imaging of the anterior segment of the eye 100 is such that the apex of the cornea of the eye 100 coincides with the alignment reference line 212-1 in the generated tomographic image with the reference mirror 153 placed at a predetermined position. First, the optical head 900 is driven. This alignment can be performed by manually driving the optical head 900 by the examiner. In this alignment, the arithmetic processing unit 171 discriminates the position of the corneal apex of the eye 100 to be examined from the tomographic image, and the drive control unit 172 matches the optical head 900 so that the position of the corneal apex coincides with the alignment reference line 212-1. It may be performed automatically by driving. Further, the portion of the eye 100 to be examined that is aligned with the alignment reference line 212-1 does not have to be the apex of the cornea, and may be a structure inside the cornea, a structure inside the anterior eye portion of the eye 100 such as an iris or a crystalline lens. .

  The principle that the working distance of the optical head 900 relative to the eye 100 is uniquely determined by adjusting the position of the optical head 900 so that the position of the corneal apex of the eye 100 coincides with the alignment reference line 212-1. This will be described with reference to (a) and (b).

  FIG. 8A shows the relationship between the reference optical path length equivalent position 220 in the OCT measurement optical path L5 and the imaging range 221 of the OCT tomographic image, and FIG. 8B shows the corneal apex of the eye 100 to be aligned with the alignment reference line 212-. The imaging range 221 of the OCT tomographic image when it does not coincide with 1 is shown. The reference optical path length equivalent position 220 is a position indicated in the OCT measurement optical path L5 where the optical path length from the optical coupler 125 is the same as the one-way optical path length of the reference optical path L4. The one-way optical path length of the reference optical path L4 is an optical path length from the optical coupler 125 to the reference mirror 153. In other words, the reference optical path length equivalent position 220 is a position where the optical path length of the measurement light 201 is the same as the optical path length of the reference light corresponding to the position of the reference mirror 153. Here, the reference optical path length equivalent position 220 generally corresponds to the uppermost position in the imaging range 221 of the tomographic image, and the OCT tomographic image is an image with the reference optical path length equivalent position 220 at the top. It becomes.

  Arranging the reference mirror 153 at a predetermined position sets the reference optical path length equivalent position 220 at a predetermined position. Here, in the OCT, a tomographic image of the inspection object is obtained from the interference light of the reference light and the measurement light 201 when the optical path length of the reference light and the optical path length of the measurement light 201 are substantially equal. Therefore, the imaging range 221 of the OCT tomographic image for the OCT measurement optical system can be set by arranging the reference mirror 153 at a predetermined position and setting the reference optical path length equivalent position 220 to a predetermined position.

  Changing the optical path length of the OCT measurement optical path L5 by driving the optical head 900 relative to the subject eye 100 so that the subject eye 100 falls within the set tomographic imaging range 221 is an optical head for the subject eye 100. The working distance of 900 will be adjusted. Accordingly, by driving the optical head 900 so that the position of the corneal apex of the eye 100 to be examined coincides with the alignment reference line 212-1 in the imaging range 221 of the OCT tomographic image, the working distance of the optical head 900 is set to a predetermined operation. The distance can be adjusted.

  Further, in the generation of an OCT tomographic image, the interference signal obtained by FFT has information of a positive component and a negative component. The above is a case where the information of the positive component is used, but when the OCT tomographic image is generated using the information of the negative component, the reference optical path length equivalent position 220 is at the bottom of the tomographic image. Corresponds to the position. Also in this case, the working distance of the optical head 900 with respect to the eye 100 can be uniquely determined by alignment similar to the alignment according to the present embodiment. In this case, unlike the case described above, the predetermined position where the reference mirror 153 is arranged is a position where the optical path length is moved to a long position by the display distance in the vertical direction of the tomographic image, that is, FIG. ) In the imaging range 221 shown in FIG.

(Optical path length correction method for anterior segment imaging)
On the other hand, the optical path length difference between the reference optical path L4 and the OCT measurement optical path L5 is due to variations in the lengths of the optical fibers 125-2 and 125-3, the air spacing of the optical system, and the refractive index and thickness of the optical elements. Basically, it is assumed that each device varies. Therefore, even if the reference mirror 153 is moved to a specific position for an arbitrary optical head 900, the reference optical path length equivalent position 220 is not constant in the OCT measurement optical path L5. That is, the working distance of an arbitrary optical head 900 with respect to the eye 100 to be examined is constant even if the reference mirror 153 is moved to a specific position due to variations in the optical path length difference between the reference optical path L4 and the OCT measurement optical path L5 for each optical head 900. I can't.

  Therefore, in this embodiment, this variation is corrected for each device, and a predetermined position where the reference mirror 153 is disposed is determined for each device. In particular, in an optical system in which the angle of view changes according to the working distance as shown in FIG. 6, this correction may be important. The predetermined position of the reference mirror 153 determined for each apparatus can be stored in the storage unit 173 or the like.

  Hereinafter, a correction method for a predetermined position where the reference mirror 153 is arranged at the time of photographing the anterior segment, that is, a correction method for the optical path length of the reference light, according to the variation among apparatuses will be described. FIG. 9 is a diagram for explaining a method of correcting the optical path length of the reference light at the time of photographing the anterior segment. FIG. 9A shows the OCT measurement optical path L5 and the reference optical path L4 when the reflective object 222 (reference reflective object) is arranged at a position away from the optical head 900 by the aforementioned working distance. In FIG. 9A, the OCT measurement optical path L5 and the reference optical path L4 are shown side by side in order to easily show the relationship between the optical path length of the measurement light 201 and the optical path length of the reference light. FIG. 9B shows an A scan data image formed from the A scan data acquired in the relationship between the OCT measurement optical path L5 and the reference optical path L4 shown in FIG.

  In FIG. 9A, the position where the optical path length of the measurement light 201 is the same as the optical path length of the reference light corresponding to the position of the reference mirror 153 is the reference optical path length equivalent position 220 in the OCT measurement optical path L5. . A reflective object 222 serving as a reference is disposed in the OCT measurement optical path L5. The reflecting object 222 is disposed at a position where the working distance of the optical head 900 with respect to the reflecting object 222 is the same as the predetermined working distance of the optical head 900 with respect to the eye 100 described above.

  When the reflective object 222 is disposed at the predetermined working distance described above with respect to the optical head 900, the A scan data obtained as a result of the interference between the measurement light 201 and the reference light is used as shown in FIG. An A-scan data image can be formed. In the A scan data image, the horizontal direction of the image corresponds to the position in the z direction (depth direction), and the vertical direction of the image corresponds to the intensity of the interference signal included in the A scan data. In addition, although it is set as the image here for description, it may be simply a graph.

  As described above, since the reference optical path length equivalent position 220 corresponds to the top of the B scan image (the shallowest position in the z direction), the peak position at the left end of the paper surface in the A scan data image is equivalent to the reference optical path length. This is the reflection point 220p corresponding to the position 220. On the other hand, the peak position located in the vicinity of the alignment reference line 212-1 is a reflection point 222p corresponding to the reflection object 222.

  Here, when the reference mirror 153 is moved along the optical axis of the reference light under the control of the drive control unit 172, the optical path length of the reference light can be changed. Since the OCT interference light is generated when the optical path length of the measurement light 201 is substantially equal to the optical path length of the reference light, the A scan data image constructed based on the OCT interference light is changed by changing the optical path length of the reference light. The imaging range can be moved. Therefore, by moving the reference mirror 153 along the optical axis of the reference light, the imaging range of the A scan data image can be moved in the z direction indicated by the arrow in the drawing.

  The reflecting object 222 is not moved because it is arranged at the predetermined working distance described above, but the peak of the reflecting point 222p in the A scan data image is moved to the alignment reference line 212 by moving the imaging range of the A scan data image. −1. Here, the reflective object 222 is disposed at a predetermined working distance. Therefore, by moving the reference mirror 153 so that the reflection point 222p coincides with the alignment reference line 212-1, the position of the reference mirror 153 when appropriately imaging an object arranged at a predetermined working distance is obtained. Can do. Thereby, the above-mentioned predetermined position of the reference mirror 153 according to the configuration of an arbitrary optical head 900 can be obtained.

  Information related to the position of the reference mirror 153 when the peak of the reflection point 222p in the A scan data image matches the alignment reference line 212-1 is stored in the storage unit 173 or the like. Here, the information related to the position of the reference mirror 153 includes, for example, information related to the position of the motor that drives the reference mirror 153 and the driving mechanism (the number of rotations of the motor, the number of steps, and the like). By performing an operation for storing information related to the reference mirror 153 for each OCT apparatus 1, measurement light caused by variations in the length of the optical fiber, the air spacing of the optical system, the refractive index and the thickness of the optical element, and the like. The variation in the optical path length difference between 201 and the reference light can be corrected. By this correction, the optical head 900 can be arranged at the predetermined working distance with respect to the eye 100 to be imaged, and the anterior eye portion of the eye 100 to be imaged can be minimized. Can do.

  Note that the scan range of the eye 100 is also changed by changing the angle range for driving the OCT scanning unit 122 that scans the measurement light 201 and changing the angle of view of the B-scan image. For this reason, in this embodiment, when the optical head 900 is arranged at the predetermined working distance described above and the anterior eye portion is imaged, an angle range for driving the OCT scanning unit 122 to image the same scan range is specified. The angle range.

  In particular, in the present embodiment, when the optical head 900 is disposed at a predetermined working distance with respect to the eye 100 to be examined, the measurement light 201 is scanned within a predetermined imaging range of the eye 100 to be measured. The OCT scanning unit 122 is driven in an angle range corresponding to the working distance. More specifically, when the anterior segment is imaged, the drive control unit 172 controls the OCT scanning unit 122 to drive in an angle range corresponding to a predetermined working distance. Thereby, when the optical head 900 is disposed at a predetermined working distance with respect to the eye 100 during photographing of the anterior eye part, the change in the angle of view of the B scan image is prevented, whereby the image of the B scan image is displayed. Changes in the field can be prevented. For this reason, the distance measurement at the time of analyzing a B scan image can be performed appropriately, and the eye 100 to be examined can be diagnosed more appropriately.

(Position of OCT focusing lens during anterior eye imaging)
When photographing the fundus, an OCT tomographic image is obtained by adjusting the position of the OCT focusing lens 123 to a different position according to the diopter of the eye 100 to be examined and photographing. On the other hand, it is generally necessary to adjust the position of the OCT focusing lens 123 when photographing the anterior eye portion to a different position depending on the working distance of the optical head 900 with respect to the eye 100 to be examined.

  Here, in the present embodiment, as described above, the optical head 900 is disposed at a predetermined working distance with respect to the eye 100 when the anterior segment is imaged. Therefore, the position of the OCT focusing lens 123 when imaging the anterior eye part can also be determined at a predetermined position (a predetermined focusing lens position) according to a predetermined working distance. Accordingly, it is not necessary to adjust the OCT focusing lens 123 when imaging the anterior eye part, the time required for imaging can be shortened, and two adjustments of adjustment of the working distance and adjustment of the OCT focusing lens 123 are performed. Complexity can be avoided.

  The positions of the focusing lens 112 and the OCT focusing lens 123 at the time of fundus photographing and anterior eye photographing are corrected for each device in advance. The correction of the positions of the focusing lens 112 and the OCT focusing lens 123 when imaging the fundus can be performed using a simulated eye to be used as a reference corresponding to each diopter as a substitute for the eye 100 to be examined. The focusing lens position between diopters is obtained by interpolation.

  For correction of the positions of the focusing lens 112 and the OCT focusing lens 123 at the time of photographing the anterior eye part, the reference reflecting object 222 (reference reflecting object) shown in FIG. This is done by obtaining the focusing lens position based on the position. For example, the position of the OCT focusing lens 123 when the brightness of the reflecting object 222 in the tomographic image becomes the highest can be obtained as the position of the OCT focusing lens 123 at the time of anterior segment imaging. That is, the reflective object 222 is disposed at a position away from the optical head 900 by a predetermined working distance, and the position where the measurement light 201 is focused on the reflective object 222 is determined based on the luminance of the reflective object 222 in the B scan image. The predetermined position of the focal lens 123 is set. Similarly, the position of the focusing lens 112 when the brightness of the reflective object 222 is highest in the two-dimensional image of the anterior segment based on the output signal from the single detector 116 is the focusing lens 112 at the time of anterior segment imaging. It can be obtained as the position of.

  In addition, the diopter of the eye 100 to be examined is obtained in advance, and the positions of the focusing lens 112 and the OCT focusing lens 123 when the reflecting object 222 corresponding to the diopter is arranged from the correction value using the simulated eye to be examined. You may ask for. For example, a plurality of simulated eye to be examined having different diopters is used as the reflecting object 222. A plurality of simulated eyes to be examined are arranged at a predetermined working distance with respect to the optical head 900, and the driving control unit 172 drives the focusing lens 112 and the OCT focusing lens 123, so that the anterior eye portion for each of the simulated eyes to be examined The position where the illumination light and the measurement light 201 are focused is obtained. Note that the focusing of the illumination light and the measurement light 201 can be determined by the arithmetic processing unit 171 based on the brightness of the simulated eye from a two-dimensional image or B-scan image of the simulated eye. Then, based on the diopter of the eye 100 to be examined, the arithmetic processing unit 171 of the control unit 170 is a predetermined position where the focusing lens 112 and the OCT focusing lens 123 are arranged from the position where the obtained anterior eye portion is focused. Select the position. In this case, the focusing lens 112 and the OCT focusing lens 123 can be disposed at a predetermined position according to the diopter of the eye 100 to be examined at the time of photographing the anterior segment.

  In either case, at the time of anterior segment imaging, the focusing lens 112 and the OCT focusing lens 123 are placed at predetermined positions for imaging. Thereby, it is not necessary to adjust the OCT focusing lens 123 when imaging the anterior eye part, and it is possible to avoid the complexity of performing the two adjustments of adjusting the working distance and adjusting the OCT focusing lens 123.

  Further, from the viewpoint of ease of adjustment, the focusing positions of the focusing lens 112 and the OCT focusing lens 123 in the anterior eye portion of the eye 100 to be examined may be different. For example, the OCT focusing lens 123 is arranged at a position where the cornea of the anterior eye part can be clearly observed, and the focusing lens 112 is arranged at a position where the iris of the eye 100 can be clearly observed, and the alignment of the optical head 900 in the xy direction. It may be easy to adjust.

(Tracking of working distance)
After the optical head 900 is adjusted to a predetermined working distance with respect to the eye 100, fixation eye movement of the eye 100 and movement of the subject occur over time, and the position of the eye 100 in the z direction moves. Is assumed. Therefore, in the OCT apparatus 1 according to the present embodiment, the position of the optical head 900 is corrected in real time so that the working distance of the optical head 900 with respect to the eye 100 is constant during anterior segment imaging. That is, the drive control unit 172 of the control unit 170 moves the optical head 900 to a position away from the subject eye 100 by a predetermined working distance according to the movement of the subject eye 100 when imaging the anterior eye portion. Let

  Specifically, the drive control unit 172 ensures that the position of the tomographic image of the anterior segment in the B scan image is always a constant position based on the position of the tomographic image of the anterior segment in the B scan image. Then, the optical head 900 is driven with respect to the eye 100 to be examined. For example, the drive control unit 172 obtains the position of the eye 100 to be examined using the A scan data of FIG. 9 and drives the optical head 900 by a distance equal to the distance between the position of the eye 100 and the alignment reference line 212-1. . By repeating this process, it is possible to perform tracking to keep the working distance constant.

  As described above, the OCT apparatus 1 according to this embodiment includes the light source 130, the optical head 900 that irradiates the eye 100 with the light emitted from the light source, and the interference light obtained through the optical head 900. The control part 170 which acquires the information of the tomogram of the optometry 100 is provided. The optical head 900 divides the light emitted from the light source 130 into measurement light 201 for irradiating the eye 100 to be examined and reference light, and combines the return light of the measurement light 201 from the eye 100 and the reference light. An interference unit for obtaining interference light. In the present embodiment, the interference unit is configured using an optical coupler 125. The optical head 900 includes an OCT scanning unit 122 that scans the measurement light 201 on the eye to be examined, and a spectroscope 180 that detects interference light. The control unit 170 acquires tomographic image information of the eye 100 based on the output signal of the spectroscope 180 of the optical head 900. Further, the optical head 900 includes a reference mirror 153 that changes the optical path length difference between the optical path of the measurement light 201 and the optical path of the reference light, and an adapter lens 105 that switches a portion of the eye 100 to which the measurement light 201 is irradiated. Prepare. Further, the optical head 900 includes an OCT focusing lens 123 that focuses the measuring light 201 on the eye 100 to be examined.

  In the OCT apparatus 1, the adapter lens 105 is placed between the eye 100 and the OCT scanning unit 122 so that the exit pupil of the optical head 900 is arranged at a finite distance when imaging the anterior segment of the eye 100. Is placed. At this time, the adapter lens 105 is disposed at the focal position of the objective lens 101-1, and is disposed at a position optically conjugate with the OCT scanning unit 122. At this time, when the optical head 900 is disposed at a predetermined working distance with respect to the eye 100 to be examined, the OCT is such that the measurement light 201 is focused on the anterior eye part and the anterior eye part enters the imaging range 221. The focusing lens 123 and the reference mirror 153 are respectively arranged at predetermined positions.

  In the OCT apparatus 1 according to the present embodiment, since the exit pupil of the optical head 900 is disposed at a finite distance when the anterior segment is imaged, the anterior segment is imaged by a non-telecentric optical system. In the OCT apparatus 1, when the anterior segment is imaged, the optical head 900 is disposed at a predetermined working distance with respect to the eye 100, so that the measurement light 201 is focused on the anterior segment and the anterior segment. Can be included in the imaging range 221. Therefore, the OCT apparatus 1 can easily perform alignment while using a non-telecentric optical system when imaging the anterior segment.

  In the OCT apparatus 1, an alignment reference line 212-1 is provided in the imaging range 221. Further, when the OCT apparatus 1 is aligned, the imaging target region of the eye 100 is arranged at the position of the alignment reference line 212-1 in the B scan image of the imaging range 221 with respect to the eye 100 to be examined. The optical head 900 is moved. For this reason, the examiner easily arranges the optical head 900 at a predetermined working distance using the B scan image of the eye 100 displayed on the display unit 190 of the OCT apparatus 1 when imaging the anterior segment. be able to.

  Furthermore, in the OCT apparatus 1 according to the present embodiment, the drive control unit 172 of the control unit 170 moves the OCT scanning unit 122 to a predetermined angular range corresponding to a predetermined working distance of the optical head 900 when imaging the anterior segment. Control to drive. For this reason, when imaging the anterior segment, the scanning range of the measurement light 201 by the OCT scanning unit 122 can be made constant, and the angle of view of the tomographic image can be made constant. For this reason, when the optical head 900 is disposed at a predetermined working distance with respect to the eye 100 to be examined, it is possible to prevent the tomographic image field from changing according to the angle range for driving the OCT scanning unit 122. . For this reason, the distance measurement at the time of analyzing a tomographic image can be performed appropriately, and the eye 100 to be examined can be diagnosed more appropriately.

  Note that the change in the scan range according to the change in the working distance of the optical head 900 with respect to the eye 100 to be examined occurs in the scanning direction of the measurement light 201, that is, the x direction and the y direction. Therefore, the change in the field of view according to the change in the working distance occurs not only in the B scan direction but also in the C scan direction, which is a direction for acquiring a plurality of B scan images when acquiring three-dimensional tomographic information. . However, in the OCT apparatus 1 according to the present embodiment, the optical head 900 can be disposed at a predetermined working distance when imaging the anterior segment of the eye 100 to be examined as described above. Therefore, when acquiring the three-dimensional tomographic information of the anterior segment, the tomographic information can be acquired in the desired imaging range not only in the x direction but also in the y direction. Medical examination of the optometry 100 can be performed.

  In this embodiment, the angle range for driving the OCT scanning unit 122 when imaging the anterior segment is determined based on a predetermined working distance so that a B-scan image in a predetermined imaging range can be obtained. On the other hand, an angle range for driving the OCT scanning unit 122 when imaging the anterior segment may be determined in advance, and a predetermined working distance may be determined based on the angle range. For example, the angle range of the OCT scanning unit 122 when imaging the fundus is set as the angle range of the OCT scanning unit 122 when imaging the anterior segment, and a predetermined working distance is determined based on the angular range. Good.

  The predetermined position where the reference mirror 153 is disposed is that the reflective object 222 is disposed at a predetermined position in the imaging range 221 when the reflective object 222 is disposed at a position away from the optical head 900 by a predetermined working distance. As described above, it is set to a position that defines the imaging range 221. Thereby, it is possible to prevent the position of the reference mirror 153 from varying when the optical head 900 is arranged at a predetermined working distance due to the variation in the optical path length difference between the measurement light and the reference light for each apparatus.

  Also, a method of correcting the variation in the optical path length difference between the measurement light and the reference light for each apparatus without arranging the reflecting object 222 at the position of the predetermined working distance can be considered.

  For example, a reflection object is arranged at a position corresponding to the fundus 202 of the eye 100 without inserting the adapter lens 105, and the peak of the reflection point corresponding to the reflection object in the A scan data image is the same as the correction method described above. Is aligned with the alignment reference line 212-1. Thereafter, information related to the position of the reference mirror 153 when the peak of the reflection point coincides with the alignment reference line 212-1 is stored in the storage unit 173 and the like in the same manner as described above.

  Further, the optical path length difference of the measurement light between the position corresponding to the fundus 202 when the adapter lens 105 is not inserted and the position corresponding to the anterior eye portion at the predetermined working distance when the adapter lens 105 is inserted is calculated. Obtain separately (experimental or calculated from design values). Then, the optical path length difference is offset from the stored position of the reference mirror 153 related to the position corresponding to the fundus 202.

  That is, in this case, the difference between the optical path length of the measurement light 201 when imaging the fundus of the eye 100 and the optical path length of the measurement light when imaging the anterior segment is obtained. Then, the reflecting object 222 is disposed at a position corresponding to the fundus 202 when the fundus 202 is imaged. Thereafter, a position that is offset by a difference in the obtained optical path length from a position that defines the imaging range 221 so that the reflective object 222 is disposed at a predetermined position of the imaging range 221 is set as a predetermined position of the reference mirror 153. To do.

  Even in this method, it is possible to prevent the position of the reference mirror 153 from varying when the optical head 900 is disposed at a predetermined working distance due to the variation in the optical path length difference between the measurement light and the reference light for each apparatus. Note that this method can also be used for other adjustments (for example, angle of view adjustment at the time of fundus imaging, center position adjustment, etc.), and therefore the adjustment time can be shortened. Note that the optical path length difference to be offset may be the optical path length difference of the respective reference light at the time of imaging of the fundus 202 and the anterior segment. In addition, since the optical path lengths of the reference light and the measurement light are substantially equal at the time of OCT imaging, the optical path length difference to be offset is the difference between the optical path lengths of the measurement light and the reference light at the time of imaging the fundus 202 and the anterior segment, It may be a difference in optical path length of measurement light.

  The correction method is not limited to the above, and the correction value can be obtained from the peak of the reflecting object position placed at an arbitrary distance (optical path length position) and the optical path length difference. Further, the correction may be obtained based on the position of the reflecting object placed at an arbitrary distance when the adapter lens 105 is inserted. Further, the correction value may be obtained by actually obtaining the measurement optical path length and the reference optical path length for the eye 100 to be examined.

[Example 2]
Hereinafter, the OCT apparatus according to the second embodiment will be described with reference to FIG. In the OCT apparatus according to the second embodiment, tracking is performed by moving the position of the reference mirror 153 according to the movement of the eye 100 to be examined, and the angle range for driving the OCT scanning unit 122 is corrected along with the movement of the reference mirror 153.

  Since the schematic configuration of the OCT apparatus according to the present embodiment is the same as that shown in the first embodiment, the same reference numerals are used for the same configuration, and description thereof is omitted. Below, it demonstrates centering on the difference with Example 1. FIG.

  In the first embodiment, the optical head 900 is driven so that the working distance between the optical head 900 and the subject eye 100 is constant as tracking for the movement of the subject eye 100. On the other hand, in this embodiment, the movement of the eye 100 is tracked by moving the position of the reference mirror 153.

  When the position of the reference mirror 153 is moved, as described in the first embodiment, the scan range of the eye 100 changes according to the working distance of the optical head 900 with respect to the eye 100. When the scan range changes, the field of view of the anterior segment B-scan image displayed in the display area 211 changes. Therefore, when the B-scan image of the anterior segment is analyzed and the distance between two points in the B-scan image such as the width of the crystalline lens is determined, for example, it is accurate due to the difference from the assumed field of view. Distance measurement may not be performed.

  On the other hand, in this embodiment, the angle range for driving the OCTX scanner 122-1 and the OCTY scanner 122-2 as the OCT scanning means 122 is corrected at the time of photographing the anterior segment so that the field of the B scan image does not change. To do.

FIG. 10 shows a state in which the angle range for driving the OCT scanning unit 122 is changed when the position of the eye 100 to be examined is moved by Δd in the z direction. In this case, the arithmetic processing unit 171 obtains the amount of movement of the reference mirror 153 based on the position of the tomographic image of the anterior segment in the B scan image. For example, the position of the eye 100 to be examined is obtained based on the A scan data shown in FIG. 9B, and the reference mirror 153 is moved by a distance equal to the distance between the position of the eye 100 and the alignment reference line 212-1. Repeat. Further, the arithmetic processing unit 171 obtains an angle range for driving the OCT scanning unit 122 according to the amount of movement of the reference mirror 153 according to the following formula 2.
2θ ′ = arctan {d × tan 2θ / (d + Δd)} (Formula 2)
Here, d is a distance serving as a reference for the eye position (the position of the adapter lens 105) of the OCT measurement optical system and the eye 100 corresponding to the predetermined working distance described in the first embodiment. θ is an angle for driving the OCTX scanner 122-1 and the OCTY scanner 122-2 when the optical head 900 is disposed at a distance d with respect to the eye 100, and Δd is an amount of movement of the reference mirror 153.

  By repeatedly performing the driving, the field of view of the B scan image can be made constant even when the reference mirror 153 is moved according to the movement of the eye 100 to be examined, and the change in the angle of view of the B scan image is prevented. As a result, the change in the field of view of the B-scan image can be prevented.

  In addition, the angle ranges of the X scanner 117-1 and the Y scanner 117-2 can be corrected in accordance with the correction of the angle ranges of the OCTX scanner 122-1 and the OCTY scanner 122-2. In this case, it is possible to prevent the field of the two-dimensional image of the anterior segment based on the output signal from the single detector 116 from changing. Furthermore, in order to acquire an image in real time in the two-dimensional observation optical path, the X scanner 117-1 and the Y scanner 117-2 are required to have high speed. From this point of view, the scanning unit 117 often uses an element such as a polygon scanner or a resonant scanner. It is difficult to change the scan angle of these elements. Therefore, in this case, it is possible to obtain the same effect as changing the angle range for driving the scanning unit 117 by changing the signal acquisition rate and acquisition timing.

  As described above, in the OCT apparatus according to the present embodiment, the drive control unit 172 of the control unit 170 captures the anterior eye part in accordance with the movement of the eye 100 to be measured. The reference mirror 153 is moved from the position. At this time, the drive control unit 172 moves the reference mirror 153 so that the anterior segment is arranged at a predetermined position that matches the alignment reference line 212-1 in the imaging range. Then, the drive control unit 172 changes the angle range for driving the OCT scanning unit 122 based on the movement of the reference mirror 153. Thereby, even when the reference mirror 153 is moved according to the movement of the eye 100 to be examined, the field of view of the B-scan image can be made constant. For this reason, the distance measurement at the time of analyzing a B scan image can be performed appropriately, and the eye 100 to be examined can be diagnosed appropriately.

[Example 3]
In the second embodiment, when tracking is performed by moving the position of the reference mirror 153 with respect to the movement of the eye 100 to be examined, the field range of the B-scan image is fixed by correcting the angle range for driving the OCT scanning unit 122. I made it. In contrast, in the OCT apparatus according to the third embodiment, the distance in the B-scan image is corrected based on the amount of movement of the reference mirror 153 when tracking the movement of the eye 100 to be examined.

  Since the schematic configuration of the OCT apparatus according to the present embodiment is the same as that shown in the first embodiment, the same reference numerals are used for the same configurations, and description thereof is omitted. Below, it demonstrates centering on the difference with Example 2. FIG.

  In the OCT apparatus according to the present embodiment, when the reference mirror 153 is moved in order to track the movement of the eye 100 during anterior eye imaging, the field of view is corrected without correcting the angle range for driving the OCT scanning unit 122. A changed B-scan image is acquired. Thereafter, when the acquired B-scan image is analyzed by the arithmetic processing unit 171, the distance in the B-scan image is corrected according to the movement amount of the reference mirror 153.

  Specifically, as in the second embodiment, the arithmetic processing unit 171 determines the amount of movement of the reference mirror 153 based on the position of the tomographic image of the anterior segment in the B scan image. For example, the position of the eye 100 to be examined is obtained based on the A scan data shown in FIG. 9B, and the reference mirror 153 is moved by a distance equal to the distance between the position of the eye 100 and the alignment reference line 212-1. Repeat. Thereafter, when analyzing the acquired B-scan image, the reference mirror 153 corrects the distance between two points in the B-scan image based on the amount of movement of the reference mirror 153. More specifically, when the reference mirror 153 moves in a direction approaching the dispersion compensation glass 152, the distance in the B-scan image is reduced according to the amount of movement of the reference mirror 153. On the other hand, when the reference mirror 153 moves in a direction away from the dispersion compensation glass 152, the distance in the B-scan image is increased according to the amount of movement of the reference mirror 153.

  As described above, in the OCT apparatus according to the present embodiment, the drive control unit 172 of the control unit 170 captures the anterior eye part in accordance with the movement of the eye 100 to be measured. The reference mirror 153 is moved from the position. At this time, the drive control unit 172 moves the reference mirror 153 so that the anterior segment is arranged at a predetermined position that matches the alignment reference line 212-1 in the imaging range. Then, the arithmetic processing unit 171 corrects the distance between the two points in the B scan image based on the movement of the reference mirror 153 when analyzing the B scan image obtained by imaging the anterior segment.

  Thereby, even when the field of view of the B-scan image changes with the movement of the reference mirror 153 for tracking the movement of the eye 100 to be examined, an arbitrary distance in the B-scan image is set within the predetermined field of view. Correction can be made according to the distance. For this reason, even when the OCT apparatus according to the present embodiment is used, distance measurement when analyzing a B-scan image can be appropriately performed, and the eye 100 to be examined can be appropriately diagnosed.

  In the first to third embodiments described above, the reference mirror 153 that changes the optical path length of the reference light is used as the optical path length changing unit. However, any optical member that changes the optical path length of the measurement light is used as the optical path length changing unit. It may be used.

  In the first to third embodiments described above, a Michelson interferometer is used as an interferometer, but a Mach-Zehnder interferometer may be used. Further, in the above embodiment, an optical coupler is used as an interference unit that divides the light from the light source 130 into measurement light and reference light, and combines the return light of the measurement light from the inspection object and the reference light to obtain interference light. Although 125 is used, the configuration of the interference unit is not limited to this. For example, when the interferometer is a Mach-Zehnder interferometer, the interfering unit is an optical coupler that divides the light from the light source 130 into measurement light and reference light, and an optical coupler that combines the return light of the measurement light and the reference light. These two optical couplers can be used. Further, a spatial optical system using a beam splitter or the like may be used instead of the optical coupler. Note that some of the components in the optical head 900 may be provided outside the optical head 900.

  Furthermore, in the first to third embodiments described above, a spectral domain OCT (SD-OCT) apparatus using an SLD as a light source has been described as the OCT apparatus. However, the configuration of the OCT apparatus according to the present invention is not limited thereto. For example, the present invention can also be applied to other types of OCT apparatuses such as a wavelength sweep type OCT (SS-OCT) apparatus using a wavelength swept light source capable of sweeping the wavelength of emitted light.

  In addition, the present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  Although the present invention has been described above with reference to the embodiments, not all combinations of features described in the embodiments are necessarily essential to the solution means of the present invention. The present invention is not limited to the above-described embodiments. Inventions modified within the scope not departing from the spirit of the present invention and inventions equivalent to the present invention are also included in the present invention. For example, in the above embodiment, the case where the object to be measured is the eye is described, but the present invention can also be applied to the object to be measured such as skin or organ other than the eye. In this case, the present invention has an aspect as a medical device such as an endoscope other than the ophthalmologic apparatus. Therefore, the present invention is grasped as an optical tomographic imaging apparatus exemplified by an ophthalmologic apparatus, and the eye to be examined is grasped as one aspect of the inspection object. Moreover, each above-mentioned Example and modification can be combined suitably in the range which is not contrary to the meaning of this invention.

1: OCT apparatus (optical tomographic imaging apparatus), 100: eye to be examined, 105: adapter lens (imaging site switching means), 122: OCT scanning means (scanning means), 130: light source, 123: OCT focusing lens (focusing) Lens), 153: reference mirror (optical path length changing means), 170: control unit (information acquisition unit), 900: optical head (measurement optical system)

Claims (20)

A light source;
The light emitted from the light source is divided into measurement light and reference light that irradiates the eye to be examined via a measurement optical system, and the return light of the measurement light from the eye to be examined and the reference light are combined. Based on the interference light obtained as described above, an information acquisition unit for acquiring information on the tomographic eye to be examined;
An optical path length changing means for changing an optical path length difference between the optical path of the measurement light and the optical path of the reference light;
With
The measuring optical system is
A focusing lens for focusing the measurement light on the eye to be examined;
Scanning means for scanning the measuring light on the eye to be examined;
Imaging part switching means for switching the part of the eye to be examined that is irradiated with the measurement light;
Including
When imaging the anterior segment of the eye to be examined,
The imaging part switching unit is arranged between the eye to be examined and the scanning unit so that the exit pupil of the measurement optical system is arranged at a finite distance,
The focusing lens so that the measurement light is focused on the anterior eye part and the anterior eye part is in the imaging range when the measurement optical system is disposed at a predetermined working distance with respect to the eye to be examined. And the optical path length changing means are respectively arranged at predetermined positions.   The optical tomography apparatus according to claim 1, wherein the information acquisition unit controls the scanning unit to be driven in a predetermined angle range corresponding to the predetermined working distance when imaging the anterior eye part. .   The predetermined angle range is an angle range determined so that the scanning unit scans the measurement light within a predetermined range of the anterior eye based on the predetermined working distance. Optical tomography system.   The said predetermined working distance is a working distance determined so that the said scanning means scans the said measurement light in the predetermined range of the said anterior eye part based on the said predetermined angle range. Optical tomography system.   The optical tomographic imaging apparatus according to claim 2, wherein the predetermined angle range is an angle range driven by the scanning unit when imaging the fundus of the eye to be examined.   The predetermined position at which the optical path length changing unit is disposed is such that the anterior eye is located at a predetermined position within the imaging range when the measurement optical system is disposed at a predetermined working distance with respect to the anterior eye portion. The optical tomographic imaging apparatus according to claim 1, wherein the optical tomography apparatus is determined so that a portion is arranged. The predetermined position where the optical path length changing means is arranged is:
Placing a reference reflecting object at a position away from the measuring optical system by the predetermined working distance;
The optical tomographic imaging apparatus according to claim 6, wherein the optical tomographic imaging apparatus is set to a position that defines the imaging range so that the reference reflective object is disposed at a predetermined position of the imaging range. The predetermined position where the optical path length changing means is arranged is:
One optical path length of the measurement light and the reference light when imaging the fundus of the subject eye and one optical path length of the measurement light and the reference light when imaging the anterior eye portion Find the difference
A reflective object is arranged at a position corresponding to the fundus when imaging the fundus;
8. The position according to claim 7, wherein the reference reflective object is set at a position offset by a difference in the obtained optical path length from a position that defines the imaging range so that the reference reflective object is arranged at a predetermined position in the imaging range. Optical tomography device. The predetermined position where the focusing lens is arranged is
Placing a reference reflecting object at a position away from the measuring optical system by the predetermined working distance;
7. The measurement light according to claim 1, wherein the measurement light is set at a position where the reference reflective object is focused based on a luminance of the reference reflective object in a tomographic image generated from the tomographic information. The optical tomographic imaging apparatus described. The reference reflective object is a plurality of simulated eye to be examined having different diopters;
The predetermined position where the focusing lens is arranged is selected based on the diopter of the eye to be examined from the in-focus positions obtained for each of the plurality of simulated eye to be examined. The optical tomographic imaging apparatus described.   The information acquisition unit moves the measurement optical system to a position away from the anterior eye portion by the predetermined working distance according to the movement of the eye to be examined when imaging the anterior eye portion. The optical tomographic imaging apparatus according to any one of claims 1 to 10. The information acquisition unit
When the anterior eye part is imaged, the optical path length changing means is arranged such that the anterior eye part is arranged at a predetermined position within the imaging range according to the movement of the eye to be examined. Moving the optical path length changing means from the position of
The optical tomography apparatus according to claim 2, wherein the angle range is changed based on movement of the optical path length changing unit. The information acquisition unit
When the anterior eye part is imaged, the optical path length changing means is arranged such that the anterior eye part is arranged at a predetermined position within the imaging range according to the movement of the eye to be examined. Moving the optical path length changing means from the position of
11. The distance between two points in the tomographic image is corrected based on the movement of the optical path length changing unit when analyzing the tomographic image generated from the tomographic information. An optical tomographic imaging apparatus according to 1. An alignment reference line is provided in the imaging range,
The measurement optical system is moved with respect to the eye to be inspected so that the region to be imaged of the eye to be examined is arranged at the position of the alignment reference line in the tomographic image of the imaging range generated from the tomographic information. The optical tomographic imaging apparatus according to any one of claims 1 to 13.   The optical tomographic imaging apparatus according to any one of claims 1 to 14, wherein the imaging region switching unit is an adapter lens disposed to face the eye to be examined.   The optical tomographic imaging apparatus according to claim 15, wherein the adapter lens has a dispersion amount equal to a dispersion from the anterior eye part to the fundus of the eye to be examined. The measurement optical system further includes an objective lens,
The optical tomographic imaging apparatus according to claim 1, wherein the imaging part switching unit is disposed at a focal position of the objective lens when imaging the anterior segment.   The optical tomography according to any one of claims 1 to 17, wherein the imaging part switching unit is disposed at a position optically substantially conjugate with the scanning unit when imaging the anterior segment. Imaging device. A light source;
The light emitted from the light source is divided into measurement light and reference light that irradiates the eye to be examined via a measurement optical system, and the return light of the measurement light from the eye to be examined and the reference light are combined. Based on the interference light obtained as described above, an information acquisition unit for acquiring information on the tomographic eye to be examined;
An optical path length changing means for changing an optical path length difference between the optical path of the measurement light and the optical path of the reference light;
With
The measurement optical system includes a focusing lens that focuses the measurement light on the eye to be examined;
When imaging the anterior segment of the eye to be examined,
The exit pupil of the measurement optical system is arranged at a finite distance,
The focusing lens so that the measurement light is focused on the anterior eye part and the anterior eye part is in the imaging range when the measurement optical system is disposed at a predetermined working distance with respect to the eye to be examined. And the optical path length changing means are respectively arranged at predetermined positions. A light source;
The light emitted from the light source is divided into measurement light and reference light that irradiates the eye to be examined via a measurement optical system, and the return light of the measurement light from the eye to be examined and the reference light are combined. Based on the interference light obtained as described above, an information acquisition unit for acquiring information on the tomographic eye to be examined;
An optical path length changing means for changing an optical path length difference between the optical path of the measurement light and the optical path of the reference light;
With
The measurement optical system includes scanning means for scanning the measurement light on the eye to be examined,
When imaging the anterior segment of the eye to be examined,
The exit pupil of the measurement optical system is arranged at a finite distance,
The optical path length changing means is arranged at a predetermined position so that the anterior eye part enters an imaging range when the measurement optical system is arranged at a predetermined working distance with respect to the eye to be examined,
The information acquisition unit is an optical tomography apparatus that controls the scanning unit to drive in a predetermined angle range corresponding to the predetermined working distance.

Images