WO2019035441A1 - Dispositif de mesure - Google Patents

Dispositif de mesure Download PDF

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Publication number
WO2019035441A1
WO2019035441A1 PCT/JP2018/030189 JP2018030189W WO2019035441A1 WO 2019035441 A1 WO2019035441 A1 WO 2019035441A1 JP 2018030189 W JP2018030189 W JP 2018030189W WO 2019035441 A1 WO2019035441 A1 WO 2019035441A1
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Prior art keywords
light
optical system
mirror
line
measurement
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PCT/JP2018/030189
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English (en)
Japanese (ja)
Inventor
朋之 池上
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キヤノン株式会社
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Publication of WO2019035441A1 publication Critical patent/WO2019035441A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions

Definitions

  • the present invention relates to a measurement apparatus for acquiring an optical interference image of an object to be inspected.
  • OCT optical coherence tomography
  • Fourier domain OCT includes spectral domain OCT (SD-OCT) and swept source OCT (SS-OCT).
  • SD-OCT spectral domain OCT
  • SS-OCT swept source OCT
  • the Fourier domain OCT uses light having a wide wavelength band, separates the obtained interference light to perform signal acquisition, and performs processing such as Fourier transformation on the acquired signal to obtain information on a tomographic image of the eye to be examined.
  • You are getting In the SD-OCT using broadband light the obtained interference light is spatially dispersed by a spectrometer to obtain information for each frequency.
  • SS-OCT using light from a wavelength-swept light source as broad-band light, interference light obtained using light of wavelengths different temporally is temporally dispersed to obtain information for each frequency.
  • a line scanning Michelson-type OCT apparatus (hereinafter referred to as a line OCT apparatus) that obtains tomographic information using measurement light shaped in a linear shape instead of using spot measurement light Is introduced in Non-Patent Document 1.
  • the line OCT apparatus the cross-sectional shape of light emitted from the light source is formed into a line shape using a collimator lens and a cylindrical lens, and measurement light is irradiated as a line beam on the fundus of the eye to be examined. Then, the measurement light returned from the fundus and the reference light similarly shaped in a line are combined, and the generated interference light is received by the line sensor.
  • the fundus is irradiated with spot light as A scan, and information obtained by line scanning the spot light as B scan is obtained at one time as a line beam in which the spot light is lined up according to the line OCT apparatus. It can be acquired. Thereby, the acquisition time of the signal corresponding to the conventional B scan can be shortened significantly.
  • Non-Patent Document 1 proposes a full-range OCT imaging technique in which a phase shift method is applied to line OCT as means for removing complex conjugate artifacts. That is, a predetermined inclination is given to the wave front of the reference light formed in a line shape, and a phase shift is generated by giving equal time delays in the B scan direction (reference light extension direction).
  • the interference signal obtained in this state is subjected to Fourier transform processing in the spatial direction of B scan instead of the normal A scan direction, and the signal is analyzed to obtain a complex conjugate interference signal. It is disclosed that a tomographic image from which a complex conjugate artifact has been removed can be obtained by setting the acquired complex conjugate interference signal to a zero value and performing normal Fourier transform processing on the remaining signal.
  • means for switching the observation method on a case-by-case basis is desired, for example, a case where it is desired to observe a locally narrow area of the subject's eye in detail or a case where an overall structure is roughly observed in a wide area.
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a measurement apparatus capable of appropriately performing imaging with a full-range OCT imaging technology and imaging with a normal OCT even with a simple configuration.
  • a measuring device concerning one mode of the present invention,
  • Light source A measurement optical system for guiding a line image obtained by shaping the measurement light from the light source to an object to be inspected;
  • a reference optical system for adjusting an optical path length of reference light from the light source;
  • a reference beam line beam forming optical system provided in the reference optical system for forming the shape of the reference light in a line shape;
  • a mirror provided in the reference optical system and capable of setting a reflection angle of the reference light;
  • Combining means for combining the reference light passing through the reference optical system and the measurement light passing through the inspection object to generate interference light;
  • Light receiving means for receiving the interference light and generating an output signal;
  • the signal processing of the output signal is different depending on whether the mirror has a predetermined angle or an angle other than the predetermined angle.
  • imaging by full-range OCT imaging technology and imaging by normal OCT can be appropriately performed.
  • FIG. 1 to be referred to is a schematic configuration view for explaining an optical system of the line OCT apparatus
  • FIG. 2 is a block diagram showing an entire configuration of the line OCT apparatus for explaining a control unit of the line OCT apparatus.
  • the line OCT apparatus shown in this embodiment has a Mach-Zehnder interference system.
  • the present invention may be configured to use a Michelson-type interference system.
  • the OCT optical system in the line OCT apparatus includes a light source 001, a coupler 002, a line beam forming optical system 101, a sample optical system (measurement optical system) 102, a reference optical system 103, a beam splitter 025, and a light receiving optical system. Having 104.
  • the light emitted from the wavelength sweepable light source 001 (SS light source) is guided to a coupler (optical coupler) 002 by an optical fiber, and is divided into measurement light and reference light by the coupler 002 with a desired division ratio.
  • the measurement light is guided to the line beam forming optical system 101, and the reference light is guided to the reference optical system 103 through an optical fiber.
  • the light from the light source 001 is guided by an optical fiber and split by the coupler 002, but may be guided as spatial light and split by a beam splitter or the like.
  • the line beam forming optical system 101 has a collimator lens 003, a cylindrical lens 004, and a lens 005 in order from the coupler 002 side.
  • the measurement light split by the coupler 002 is guided to the line beam forming optical system 101, and is collimated by the collimator lens 003.
  • the collimated light is further shaped by the cylindrical lens 004 and the lens 005 into a line beam whose cross-sectional shape is a line on the virtual plane 006.
  • a solid line indicates a light beam condensed on the virtual plane 006 in the sagittal direction perpendicular to the paper
  • a broken line indicates a light beam collimated on the virtual plane 006 in the tangential direction parallel to the paper.
  • the measurement light passes through the beam splitter 025 and is guided to the sample optical system 102.
  • the sample optical system 102 includes, in order from the beam splitter 025 side, a focus lens 007, an aperture 008, a galvanometric mirror 009, a lens 010, and an objective lens 011.
  • the galvanometric mirror 009 is disposed at a position substantially conjugate with the anterior segment of the subject eye 012, and the angle with respect to the optical axis is variable.
  • the lens 010 and the objective lens 011 form an objective lens system, and guide measurement light to the eye 012 to irradiate a line beam onto the fundus.
  • the focus lens 007 is movable on the optical axis by a focus drive unit 0081 described later.
  • the position on the optical axis of the focus lens 007 is controlled such that the virtual plane 006 and the fundus of the eye 012 are optically conjugate.
  • the measurement light (line beam) irradiated onto the fundus is scanned on the fundus in the state of a line beam by rotational driving of the galvanometric mirror 009.
  • the measurement light reflected and scattered by the fundus of the eye to be inspected 012 is transmitted back to the above-described optical element in the sample optical system 102 as return light, and then reaches the beam splitter 025.
  • the return light reflected by the beam splitter 025 is guided to the light receiving optical system 104, and forms linear measurement light (return light) on a virtual plane 026 described later.
  • a virtual plane 026 located in the vicinity of the exit surface of the beam splitter 025 is optically conjugate to the fundus of the eye 012 and the virtual plane 006. Furthermore, the virtual plane 026 is also conjugated with the light receiving surface of the line sensor 029 via the lens 027 and the lens 028. Therefore, the measurement light (return light) reflected and scattered from the irradiation position of the line beam on the fundus reaches the line sensor 029 and forms an image.
  • the reference optical system 103 includes a collimator lens 014, an ND filter 015, a mirror 016, a mirror 018, a retro reflector 017, a mirror 019, a cylindrical lens 020, a lens 021, a wavefront tilt mirror 022, a lens 023, and a lens 024. These configurations are arranged in order from the exit end of the optical fiber.
  • the reference light collimated by the collimator lens 014 passes through the ND filter 015 and is attenuated to a predetermined light amount. Thereby, adjustment of the light quantity difference of the measurement light and reference light which passed the fundus is made.
  • the reference light is reflected by the mirror 016 and the mirror 018 while keeping the collimated state, is reflected by the retroreflector 017 movable in the optical axis direction, and is reflected by the mirror 018, the mirror 016 and the mirror 019 . Further, the reference light is shaped by the cylindrical lens 020 and the lens 021 to form a linear line beam as an intermediate image on the wavefront tilt mirror 022.
  • the line beam as an intermediate image may be referred to as an intermediate line image.
  • the cylindrical lens 020 and the lens 021 constitute a line beam forming lens system for reference light.
  • the line-like intermediate image formed on the wavefront tilt mirror 022 passes through the beam splitter 025 through the lens 023 and the lens 024 to form a line beam of reference light on the virtual plane 026.
  • the lens 023 and the lens 024 constitute a relay lens system for reference light. Since the virtual plane 026 is also conjugate with the light receiving surface of the line sensor 029 as described above, as a result, the intermediate line beam is in a conjugate relationship with the light receiving surface of the line sensor 029.
  • the interference optical system is constituted by the beam splitter 025.
  • the reference light that has passed through the reference optical system 103 and the measurement light that has passed through the fundus of the subject's eye 012 via the sample optical system 102 are combined by the beam splitter 025 and each line of the reference light and measurement light is on the virtual plane 026.
  • the beams interfere.
  • the interfered line beam is received by the line sensor 029 through the lens 027 and the lens 028, and the obtained output signal is output from the line sensor 029.
  • a polarization adjusting paddle 013 in which the optical fibers are bound in a plurality of rings, is disposed.
  • a polarization adjustment drive unit 0061 for driving the polarization adjustment paddle 013 is disposed in addition to the polarization adjustment paddle 013.
  • the line OCT apparatus in the present embodiment includes a sampling unit 030, a memory 031, a signal processing unit 032, a monitor 033, an operation input unit 034, and a control unit 035 in addition to the OCT optical system described above. It has a control system.
  • the control unit 035 is configured by a general-purpose computer or the like, and is connected to the sampling unit 030, the memory 031, the signal processing unit 032, the monitor 033, and the operation input unit 034. Then, input of control signals and the like to these configurations, reception of output signals from these configurations, and the like are performed.
  • the operation input unit 034 is an input device for instructing the control unit 035, and is configured of, for example, a keyboard, a mouse, and the like.
  • the monitor 033 displays various information and various images sent from the control unit 035, a mouse cursor according to the operation of the operation input unit 034, and the like.
  • the sampling unit 030 is connected to the line sensor 029 and controls the line sensor 029 to acquire an interference signal at a predetermined timing.
  • the memory 031 stores the acquired interference signal, position information of the galvanometric mirror 009, various information related to measurement of an image generated from the interference signal, various programs for executing the measurement, and the like.
  • the signal processing unit 032 performs processing such as Fourier transform on the interference signal acquired by the sampling unit 030 to generate tomographic information such as luminance information and a tomographic image.
  • processing such as Fourier transform on the interference signal acquired by the sampling unit 030 to generate tomographic information such as luminance information and a tomographic image.
  • control unit 035, the monitor 033, and the like described herein are individually shown in the drawing, they may be configured integrally or partially. Further, the control unit 035 and the OCT optical system may be integrally configured.
  • the control unit 035 is also connected to the light source 001, the line sensor 029, the mirror drive unit 051, the polarization adjustment drive unit 0061, the reflector drive unit 0071, the focus drive unit 0081, and the galvano drive unit 0091 in addition to the configuration described above. There is. These configurations are for control of each configuration of the OCT optical system, and control of each configuration in the OCT optical system by the control unit 035 is also possible.
  • the focus driver 0081 moves the focus lens 007 in the optical axis direction to control the position of the focus lens 007 on the optical axis.
  • the galvano drive unit 0091 drives the galvanometric mirror 009 to scan the fundus of the line-shaped measurement light.
  • the reflector drive unit 0071 moves the retroreflector 017 in the optical axis direction, and adjusts the optical path length difference between the optical path length of the measurement light and the optical path length of the reference light.
  • the control unit 035 further performs light emission control of the light source 001, control of acquisition timing of an interference signal to the sampling unit 030, and the like.
  • the output signal from the line sensor 029 is acquired by the sampling unit 030.
  • the galvano drive angle of the galvanometric mirror 009 is controlled by the galvano drive unit 0091.
  • the sampling unit 030 obtains this output signal for each pixel of the line sensor 0029 corresponding to one wavelength sweep of the light source 001 at an arbitrary galvano drive angle, and each pixel obtains one interference signal.
  • this output signal is acquired for each pixel of the line sensor 029 in response to one wavelength sweep of the light source 001 to obtain the next interference signal. Thereafter, interference signals are acquired one after another by this repetition.
  • the interference signal acquired by the sampling unit 030 is stored in the memory 031 together with the galvano drive angle.
  • the galvano drive angle is associated with the scanning position of the measurement light on the fundus.
  • the interference signal stored in the memory 031 is frequency-analyzed by the signal processing unit 032 and associated with the position on the fundus.
  • the tomographic image of the fundus of the eye to be examined 012 generated by the above processing is stored in the memory 031 and displayed on the monitor 033. As described above, a three-dimensional fundus volume image can be generated and displayed on the monitor 033 by acquiring information of the galvano drive angle together with the interference signal.
  • FIGS. 3A and 3B illustrate in detail the cylindrical lens 020, the lens 021, the wavefront tilt mirror 022, the lens 023 and the lens 024 which are a part of the reference optical system 103 shown in FIG.
  • An intermediate line image is formed on the wavefront tilting mirror 022 by the cylindrical lens 020 and the lens 021.
  • the wavefront tilt mirror 022 shown in FIG. 3A is disposed in the 45-degree direction with respect to the optical axis, whereby the central axis of the reference light after reflection coincides with the optical axis of the later optical system. .
  • the positional relationship between the lens 023 and the lens 024 will be described.
  • the focal length of the lens 023 is F23
  • the lens 023 is disposed at a distance from the wavefront tilting mirror 022 by F23. That is, the intermediate line image coincides with the front focal plane of the lens 023.
  • a pupil image of an intermediate line image is formed on a virtual plane SP which is a back focal plane of the lens 023. That is, the light beam in the sagittal direction indicated by the solid line collimated in the intermediate line image is condensed on the virtual plane SP, while the light beam in the tangential direction indicated by the dashed line collected in the intermediate line image is the virtual plane SP It is collimated above. That is, in a state in which the line axis is rotated by 90 degrees, a pupil image of an intermediate line image is formed on the virtual plane SP.
  • the lens 024 when the focal length of the lens 024 is F24, the lens 024 is disposed at a distance F24 from the virtual plane SP. That is, the virtual plane SP coincides with the front focal plane of the lens 024. At this time, a line beam relayed to the intermediate line image is formed on the back focal plane of the lens 024. If F23 and F24 are equal, these line beams are equal and if different, they become line beams with a magnification corresponding to the ratio. If the entire reference optical system is arranged so that the back focal plane of the lens 024 coincides with the virtual plane 026 on which the line image of the measurement light (return light) passing through the sample optical system 102 is formed, the virtual plane 026 is obtained. The reference light and the measurement light are combined in Therefore, from the interference signal having no phase shift obtained in this state, a tomogram having no inclination is obtained as shown, for example, as a tomogram Ta1 in FIG. 4 described later.
  • FIG. 3B shows the case where the wavefront tilt mirror 022 is given a tilt different from 45 degrees.
  • the tilt change of the wavefront tilting mirror 022 can be controlled by the control unit 035 through a stepping motor (not shown) or the like attached to the wavefront tilting mirror 022 by the mirror driving unit 0051.
  • the wavefront tilt mirror 022 is given a tilt of 45 + ⁇ / 2 degrees, the central angle of the reference light after reflection is tilted by ⁇ .
  • the light beam in the collimating direction is uniformly inclined by ⁇ , and at the same time, the wavefront which is an equiphase surface of the reference light is also inclined by ⁇ .
  • the reference light having passed through the lens 023 forms a pupil image on the virtual plane SP, but the formation position is shifted by F23 ⁇ tan ⁇ .
  • a lens 024 forms a line beam of reference light relayed on the virtual plane 026.
  • the collimated beam directed to the virtual plane 026 is also inclined uniformly by ⁇ ′. That is, the wavefront of the reference light on the virtual plane 026 is inclined by ⁇ ′.
  • the intermediate line image on the wavefront tilt mirror 022 is in a conjugate relationship with the virtual plane 026 via the lens 023 and the lens 024. For this reason, the center of the reference light reflected at the optical axis center of the wavefront tilt mirror 022 reaches the optical axis of the optical system again without being shifted on the imaginary plane 026.
  • the configuration of the reference light relay lens system is not limited to that shown here, and various changes may be made as long as the intermediate line image formed on the wavefront tilt mirror 022 is relayed on the virtual plane 026. It is possible.
  • FIG. 4 shows an example of a tomogram of the fundus of the eye to be examined 012 obtained by the signal processing unit 032.
  • Ta1 is a tomogram acquired when the wavefront of the reference light is not inclined (angle ⁇ ).
  • the wavefront of the reference light is inclined (angle ⁇ ) by the wavefront inclination mirror 022, a tomographic image in which the whole is inclined like Tb1 is obtained.
  • the uniform inclination of the wavefront is generally referred to as a phase shift, and causes a uniform phase delay in the B-scan direction, so that the tomographic image Tb1 has a linear depth in addition to the shape of the tomographic image Ta1.
  • FIG. 5 is an example of a processing process called full range processing by the signal processing unit 032.
  • the following processing disclosed in Non-Patent Document 1 is performed.
  • Fourier transform processing is performed on the interference signal from the subject eye 012 acquired by the line sensor 029 in the B-scan direction, and frequency analysis of the structure of the acquired data is performed.
  • a separable true image (real image) and a mirror image of the frequency signal are obtained.
  • the complex image of the original interference signal can be obtained by performing inverse Fourier transform processing on the normal image.
  • the horizontal axis of the graph shown in FIG. 5 is frequency, and the vertical axis is intensity.
  • the frequency distribution Sa1 indicated by a solid line is a frequency distribution when the frequency analysis is performed in a state where the wavefront of the reference light is not inclined. This corresponds to the tomographic image Ta1 in FIG.
  • a distribution having a peak on the + side of the frequency corresponds to a normal image
  • a distribution having a peak on the ⁇ side corresponds to a mirror image.
  • This distribution spreads across the zero frequency, and furthermore, a mirror image and an orthoimage generated in left-right symmetry overlap. In this state, separation and removal of the mirror image is not easy.
  • it is difficult to display correct tomographic information in the region where the normal image and the mirror image overlap so it is possible to avoid this region and to use only the tomographic information at a relatively shallow depth left.
  • the frequency distribution Sb1 indicated by a broken line is a frequency distribution when frequency analysis is performed in a state where the wavefront of the reference light is inclined.
  • the two distributions are located apart from each other at the zero frequency, and further, the normal image and the mirror image are separated.
  • the wavefront tilt mirror 022 is such that, in a light beam reaching the line sensor 029, a phase difference of ⁇ c / 4 is uniformly given between adjacent pixels of the line sensor.
  • the inclination angle of is set, separation of the frequency distribution becomes possible well. In such a state, the frequency distribution shown in FIG.
  • the mirror image frequency signal can be easily set to a zero value, and the mirror image can be removed. Therefore, acquisition of tomographic information from a wide range of wavelengths in wavelength-swept light is possible, and tomographic information from a deeper depth can be obtained.
  • FIG. 6 shows a tomogram acquired by giving an inclination to the wavefront of the reference light to an area with a large inclination such as the periphery of the fundus of the eye to be examined 012.
  • a tomogram Ta2 in FIG. 6 shows a tomogram obtained when the wavefront of the reference light is inclined at a fixed value.
  • FIG. 7 shows the frequency distribution corresponding to each of the tomographic images shown in FIG. 6, and the frequency distribution Sa2 corresponds to the tomographic image Ta2.
  • the frequency distribution Sa2 partially crosses the zero frequency, and further, an orthoimage and a mirror image slightly overlap. For this reason, it is not easy to remove only the mirror image as described above.
  • the tomographic image Tb2 in FIG. 6 is a tomographic image obtained by giving a sufficient inclination to the wavefront of the reference light with reference to the inclination of the tomographic image Ta2.
  • a further tilt is added by the mirror driving unit 0051 to give a larger phase shift to the wavefront of the reference light.
  • the mirror frequency signal can be easily set to a zero value, and the mirror image can be removed. That is, by suitably controlling the tilt angle of the wavefront tilt mirror 022, a tomographic image having a desired tilt can be obtained over a wide area even for the fundus of the subject eye 012 having various tilts. Becomes possible.
  • FIG. 8 is a view for explaining the appearance of the change of the wavefront in the case of diverging the collimated light of the reference optical system 103 for the purpose of coping with such an eye to be examined.
  • a cylindrical lens drive unit (not shown) for focusing and driving the cylindrical lens 020 in the optical axis direction is added to the configuration shown in FIG.
  • the cylindrical lens 020 is defocused from the initial position in the direction of the arrow by the cylindrical lens driving unit.
  • the light beam in the tangential direction indicated by the broken line after passing through the lens 021 is not collimated but diverged.
  • the cylindrical lens drive unit may be configured to be independent, for example, controlled by the control unit 35, or may be configured to be included or shared by the control unit 035 or the focus drive unit 0081.
  • An intermediate image is formed on the wavefront tilt mirror 022 as a diverging line beam, and the wavefront of the reference light is tilted by the reflection of the wavefront tilt mirror 022.
  • the reflected reference light is relayed by the lens 023 and the lens 024 as a diverging line beam on the virtual plane 026.
  • the pupil image formed by the lens 023 is on the rear side of the virtual plane SP. Accordingly, the wavefront WF formed of the equiphase surface of the divergent light beam in the tangential direction generated by the lens 024 is curved in an arc shape, and the peripheral region lags behind the central region of the light beam and reaches the virtual plane 026.
  • FIG. 9 is a view showing an example of a tomogram acquired in a state in which the wavefront inclination mirror 022 is tilted with respect to the fundus of the subject eye 012 having a large curvature in the fundus described above.
  • the tomographic image Ta3 is an example of a tomographic image acquired in a state where the cylindrical lens 020 is at the initial position, that is, in a state in which the reference light is collimated as usual. As shown in the figure, the tomographic image Ta3 is affected by the curvature of the fundus, and the central region is deep and the peripheral portion is shallow. That is, the tomogram Ta3 has a structure having various inclination components from the central area to the peripheral area.
  • FIG. 9 is a view showing an example of a tomogram acquired in a state in which the wavefront inclination mirror 022 is tilted with respect to the fundus of the subject eye 012 having a large curvature in the fundus described above.
  • the frequency distribution Sa3 has a wide frequency distribution due to the influence of the structure of the fundus, and a part of the frequency distribution Sa3 crosses the zero frequency, and further, the normal image and the mirror image slightly overlap. For this reason, it is not easy to remove only the mirror image as described above.
  • the tomographic image Tb3 in FIG. 9 is a tomographic image obtained in a state in which the cylindrical lens 020 is defocused. Specifically, the cylindrical lens 020 is moved in the direction of the lens 021 in the optical axis direction by the cylindrical lens drive unit, and the wavefront indicated by WF in the drawing is given to the reference light. In the present embodiment, this process is performed with reference to the tomographic image Ta3. As shown in the figure, by defocusing the reference light, an increase in the optical path length of the peripheral region of the reference light itself offsets the shallowness of the depth of the peripheral portion of the original fundus. Therefore, the tomogram to be obtained has a structure having a component of uniform slope as a whole. In the example shown in FIG.
  • the frequency distribution Sb3 is suppressed to a narrower range, does not span zero frequency, and the normal image and the mirror image are further separated.
  • the mirror frequency signal can be easily set to a zero value, and the mirror image can be removed. Therefore, even when the subject eye 012 having various tilt components is targeted by the curvature of the fundus, it is possible to acquire a tomogram that fits within a desired frequency distribution.
  • FIG. 11 exemplifies a tomogram in the case of imaging the fundus oculi peripheral region of the intensity myopic eye.
  • the eye to be examined has a large curvature in its entirety for myopia intensities, and the whole is in a tilted state for a peripheral region. In such a state, the left region of the tomographic image Ta4 is at a shallow position, and the central and right regions are at a deep position.
  • the region at the upper end of the tomogram has a low frequency of an interference signal and high sensitivity can be obtained.
  • the signal sampling by the sampling unit 030 acts as a low pass filter, and the sensitivity is lowered. Therefore, in the tomographic image Ta4, the left region is high in sensitivity, and the center and right regions are low in sensitivity, and an image with good sensitivity as a whole can not be obtained.
  • the tomographic image Tb4 is obtained by suitably controlling the wavefront of the reference light by adjusting the inclination of the wavefront inclination mirror 022 and the defocus of the cylindrical lens 020.
  • the wavefront inclination mirror 022 is adjusted according to the peripheral region of the subject eye 012 and the wavefront of the reference light is inclined to obtain a state in which the curvature approaches symmetrical in the left-right direction.
  • the cylindrical lens 020 is moved in the direction of the optical axis to defocus, thereby flattening the entire curvature.
  • it may be judged with reference to a tomogram, for example, based on whether or not the frequency distribution can be separated as shown in FIG. .
  • the tomogram Tb4 obtained by the above operation results in a tomogram of a shape different from normal.
  • both control amounts in focus control of the cylindrical lens 020 and angle control of the wavefront tilt mirror 022 are known. Therefore, by acquiring these and performing image processing for rearranging the pixels of the image in the tomogram based on the both control amounts, an image with improved image quality is obtained with the normal shape of the tomogram Ta4.
  • the line OCT apparatus has a switching function between a normal imaging mode and an imaging mode for performing full range processing (hereinafter, full range mode). That is, the operation control of the wavefront tilt mirror 022 and the cylindrical lens 020, and the processing method of the interference signal by the signal processing unit 032 are switched in conjunction with the on / off of the full lens mode. Further, the image resolution of the tomogram to be displayed is also changed according to this switching.
  • FIG. 12A and 12B show examples of user interface screens of the control application displayed on the monitor 033.
  • FIG. 12A shows an example of a display screen when the full range mode is off.
  • a tomographic image display unit 201a an anterior eye observation image display unit 202, and a fundus observation image display unit 203 are disposed to display an image.
  • a focus drive control slider 204 a reference system reflector drive control slider 205, an OCT observation preview start button 206, an OCT imaging button 207, a full range mode button 208, and an angle of view switching button 209 are displayed.
  • the tomogram display unit 201a displays a tomogram acquired by the present OCT optical system.
  • the anterior eye observation image display unit 202 displays an anterior eye observation image acquired by an anterior eye observation optical system (not shown) used for alignment of the subject eye 012.
  • the fundus oculi observation image display unit 203 displays a fundus oculi observation image acquired by the fundus oculi observation optical system (not shown) used for specifying the observation region of the fundus oculi.
  • the user uses the operation input unit 034 to input various commands to the line OCT apparatus by performing the above-described slider adjustment or button on / off operation. For example, by performing the on / off operation of the full range mode button 208, the on / off of the full range mode is switched.
  • FIG. 12A A display example when the full range mode is off is shown in FIG. 12A.
  • a tomographic image in which the imaging depth is within a normal narrow range is displayed on the tomographic image display unit 201a.
  • the depth range is insufficient and the peripheral region of the tomogram is folded back and displayed as shown in the figure, which is unsuitable for wide-area observation of the fundus It becomes.
  • FIG. 12B shows a display example when the full range mode is on.
  • the full range mode button 208 is turned on via the operation input unit 034, the tilt angle of the wavefront tilt mirror 022 is adjusted, and a tomogram to which the full range processing is applied is acquired in the signal processing means 032.
  • a tomogram corresponding to the full range processing is displayed on the tomogram display unit 201b of FIG. 12B.
  • the image height of the acquired tomogram is doubled in the tomogram display unit.
  • the horizontal pixel resolution is halved in the process of full range processing, the image is resized twice to maintain the image width.
  • control unit 035 as a display control unit and automatically changing the control mode of the monitor 033, a series of complex operations related to the full range processing including the optical system can be performed by a simple user operation of only the switching button. Control can be switched in conjunction.
  • the analysis function of the control unit 035 may be interlocked and switched according to the switching so as to correspond to the feature of the tomogram obtained each time.
  • the obtained tomogram is characterized in that the depth range is narrow and the lateral resolution is fine.
  • a macular area analysis function, an optic disc analysis function, etc. can be considered.
  • the tomographic image to be obtained is characterized in that although the depth range is wide, aliasing of the tomographic image around the fundus is difficult to occur, but the lateral resolution is coarse.
  • a function to roughly analyze a wide range suitable for this feature may be the reticular film thickness distribution analysis function, etc.
  • the analysis including up to the periphery of the fundus may lead to early detection of diseases such as glaucoma. high. That is, when the full range mode button 208 is switched on and off, analysis modes suitable for each may be executed in conjunction.
  • the inclination angle of the wavefront tilting mirror 022 with respect to the optical axis is adjusted according to the structure of the fundus. . That is, in the case of a fundus structure that requires full range processing, a uniform phase difference is given to the wavefront of the light beam of the reference light, and full range processing is applied to the obtained interference signal to obtain a tomogram with doubled depth. It is possible to acquire. In addition, when the full range processing is unnecessary, the phase difference given to the wavefront is eliminated by adjusting the inclination angle, and it is possible to obtain a tomographic image with excellent resolution even if the depth is relatively shallow.
  • the on / off switching is facilitated by interlocking the on / off switching of the optical system, the signal processing, and the analysis mode with the on / off of the full range processing by the user interface operation on the monitor screen. This makes it possible to diagnose the subject eye having various fundus structures or to acquire and analyze a tomogram according to the diagnosis.
  • Non-patent Document 1 For example, in the case of making the inclination of the wavefront of the reference light variable, it is also conceivable to realize the generation of the inclination of the wavefront only at the relative angle of the two mirrors in the reference mirror as in Non-patent Document 1.
  • this relative angle is changed, not only the change of the desired inclination on the line sensor but also the shift deviation of the optical path occurs simultaneously.
  • a configuration may be considered in which the interference system is configured as a Mach-Zehnder type, and then the entire reference optical system is rotated using the gonio stage with the center of the line sensor as the rotation axis.
  • the measurement apparatus includes the light source 001, the sample optical system 102, the reference optical system 103, the beam combining means (beam splitter 025), and the light receiving means (line sensor 029). , And a signal processing unit 032.
  • the measurement apparatus further includes a reference light line image forming optical system, a reference light relay optical system, and an inclined mirror.
  • the sample optical system 102 shapes the measurement light obtained by dividing the light from the light source 001 as a line image and guides it to the object to be inspected (the fundus of the eye to be inspected 012).
  • the reference optical system adjusts the optical path length of the reference light obtained by dividing the light from the light source 001 corresponding to the measurement light.
  • the combining means combines the reference light passing through the reference optical system and the measurement light passing through the fundus to generate interference light, and the light receiving means receives the interference light to generate an output signal.
  • the signal processing unit 032 subjects the output signal to the above-described processing such as Fourier transform, and outputs measurement information such as a tomographic image of the fundus.
  • the line image forming optical system for reference light is constituted of the cylindrical lens 020 and the lens 021 in the above-mentioned embodiment to form an intermediate line image of the reference light.
  • the reference light relay optical system includes at least a first lens (lens 023) and a second lens (lens 024), and the intermediate line image and the line sensor 029 have a conjugate relationship.
  • an inclined mirror (wavefront inclined mirror 022) is disposed at the image forming position of the intermediate line image, and the reference light in a line shape is reflected and guided to a reference light relay optical system.
  • the tilt mirror can change the reflection angle of the reference light, and gives a tilt (phase shift) to the wavefront of the reference light by changing the tilt angle with respect to the optical axis.
  • the lens which comprises this relay optical system for reference lights may be comprised from single-piece
  • the reference light relay optical system is composed of a first lens group and a second lens group.
  • the intermediate line image coincides with the front focal plane of the first lens group
  • the optical surface of the light receiving means coincides with the rear focal plane of the second lens group
  • the optical system arrangement is such that the back focal plane of the lens group coincides with the front focal plane of the second lens group.
  • These optical systems may be disposed independently of the reference optical system in the sense of adjusting the optical path length of the reference light.
  • the light receiving means includes a line sensor.
  • the line sensor is not limited as long as it has the same function.
  • the measuring apparatus further includes a line beam forming optical system 101 for forming the measurement light as a line beam.
  • the line beam forming optical system 101 is provided with line beam forming lenses having different curvatures in two meridian directions orthogonal to each other.
  • a cylindrical lens 004 is used as the line beam forming lens.
  • the measurement apparatus further includes a dividing unit (coupler 002) that divides the light from the light source 001 into the measurement light and the reference light.
  • the reference optical system 103 forms a second line beam as a line beam generated from the reference light, and the beam splitter 025 combines the line beam and the second line beam to generate a line-like interference light.
  • the signal processing means 032 performs the above-described full range processing of generating measurement information by removing a mirror image from a real image and a mirror image obtained by frequency analysis of an output signal from the line sensor 029.
  • the measurement apparatus further includes a control unit 035 that controls the reflection angle of the reference light in the tilt mirror (wavefront tilt mirror 022).
  • the control unit 035 changes the reflection angle of the reference light of the tilt mirror depending on whether or not the full range processing in the signal processing unit 032 is performed.
  • the measuring device further includes display means (monitor 033) for displaying the measurement information.
  • the control unit 035 changes the display mode of the measurement information by the display unit, for example, from FIG. 12A to FIG.
  • the reference beam line beam forming optical system (cylindrical lens 020 and lens 021) can be defocused by, for example, the control unit 035 or the focus driving unit 0081.
  • the measurement apparatus further includes a scanning unit (galvanometric mirror 009) for scanning the line image of the measurement light in a direction perpendicular to the extending direction of the line image on the test object (the fundus of the subject eye 012).
  • a wavelength sweeping type light source for sweeping the wavelength of the light to be emitted is used.
  • the present embodiment differs from the above-described first embodiment in that the optical system is variable in magnification.
  • the angle of view be switched according to the situation, for example, when it is desired to photograph the fundus at a wide angle of view or when it is desired to partially photograph at a narrow angle of view with high resolution.
  • imaging is performed at a wide angle of view, it is often prioritized to obtain a signal at a wider depth because a tomogram is easily folded at the periphery.
  • finer image resolution is often prioritized.
  • the full range mode is switched in conjunction with the appropriate situation for each situation, the operability of the user is improved.
  • the present embodiment addresses such a request.
  • FIG. 13 shows a schematic configuration diagram of an OCT optical system according to the present example.
  • the same reference numerals are used for the same components as those described in the first embodiment, and the description thereof is omitted. Below, the configuration different from the first embodiment will be described in detail.
  • the OCT optical system according to the present embodiment differs in that, in the sample optical system 102, an objective lens 011b is disposed, which makes the focal length of measurement light smaller than in the first embodiment.
  • the focal length of the objective lens By reducing the focal length of the objective lens, the light beam in the tangential direction indicated by the broken line of the measurement light is incident on the subject eye 012 at a large angle of view. For this reason, the fundus can be imaged at a wide angle of view in the tangential direction.
  • the diameter of the beam irradiated to the pupil becomes smaller, so the focused spot on the fundus becomes larger and the lateral resolution is lowered.
  • the focal length of the objective lens 011 b is long, the characteristics contrast with the characteristics described here, and a tomogram with a narrow angle of view and improved lateral resolution can be obtained.
  • the focal length of the objective lens 011 b variable, it is possible to control the angle of view and the lateral resolution.
  • a plurality of objective lenses 011 having large and small focal distances are built in the apparatus, and the focal distances can be made variable by replacing them by electric drive.
  • the objective lens 011 may be configured separately from the apparatus main body so as to be removable, and may be replaced manually by the user.
  • a zoom optical system composed of a plurality of lenses may be disposed at the position of the objective lens 011 or at the position where the objective lens 011 and the lens 010 are arranged, thereby making the focal length variable.
  • variable part is an objective lens
  • the sample optical system 102 may be changed in magnification by changing the focal length of the lens 010. That is, as long as the measurement magnification in the sample optical system 102 can be arbitrarily changed, the specific configuration is not limited to the one described here.
  • a view angle switching button 209 is arranged on the user interface screen for control application displayed on the monitor 033.
  • a wide angle of view imaging control state (hereinafter, wide angle of view mode) is selected by user operation using the angle of view switching button 209.
  • the focal length of the objective lens 011 is switched by the control unit 035, and the full range mode is turned on.
  • the tilt angle of the wavefront tilt mirror 022, the defocus of the cylindrical lens 020, the processing mode of the interference signal by the signal processing unit 032, and the display image resolution of the monitor 033 are switched in conjunction.
  • the full range mode button 208 is automatically displayed in the on state.
  • the objective lens 011 is configured to be manually replaced by the user, by providing a detection sensor in the objective lens module, the wide field angle mode and the full range mode are automatically switched in conjunction with completion of the replacement work. It is good also as control.
  • the sample optical system 102 includes an optical variable magnification system that changes the angle of view when the measurement object is irradiated to the test object (the fundus of the subject eye 012).
  • the optical variable magnification system corresponds to, for example, a configuration in which the lens is changed from 011 to 011 b.
  • the control unit 035 determines whether or not the above-described full range processing is performed according to the change of the angle of view of the optical magnification changing system, the reflection angle of the reference light from the wavefront tilt mirror 022, and the tomographic image of the monitor 033. Change the display style.
  • the imaging angle of view and the imaging depth are interlocked and switched according to the feature of the fundus of the eye to be examined, and a series of complex controls including the optical system are interlocked and switched by simple user operation. be able to.
  • the fundus of the human eye is taken as an example of the object to be examined.
  • the object to be examined is not limited to the fundus, and may be an anterior segment, vitreous body, or the like.
  • the line OCT apparatus described above can also be configured as a measurement apparatus for medical equipment such as an endoscope other than the ophthalmologic apparatus.
  • the present invention provides a program that implements 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 execute the program. It can also be realized by a process of reading out and executing. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.
  • a program that implements 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 execute the program. It can also be realized by a process of reading out and executing. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.
  • a circuit eg, an ASIC

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Abstract

L'invention fournit un dispositif de mesure qui permet d'exécuter de manière appropriée une capture d'image selon une technique de capture d'image par tomographie par cohérence optique de gamme complète, et une capture d'image par tomographie par cohérence optique normale, y compris dans le cas d'une configuration simple. L'objet de l'invention est équipé : d'une source de lumière ; d'un système optique de mesure qui guide une image linéaire telle qu'est formée une lumière de mesure provenant de la source de lumière vers un objet d'inspection ; d'un système optique de référence qui régule la longueur de trajet lumineux d'une lumière de référence provenant de la source de lumière ; d'un système optique de formation de faisceau linéaire pour lumière de référence qui est agencé sur ledit système optique de référence, et qui donne à ladite lumière de référence une forme linéaire ; d'un miroir qui est agencé sur ledit système optique de référence, et qui permet d'établir un angle de réflexion de ladite lumière de référence ; d'un moyen de multiplexage qui multiplexe la lumière de référence passée par le système optique de référence, et la lumière de mesure passée par l'objet d'inspection, et qui génère une lumière d'interférence ; et d'un moyen récepteur qui reçoit la lumière d'interférence et génère un signal de sortie. Dans le cas où le miroir établit un angle prédéfini et dans le cas où il établit un angle différent dudit angle prédéfini, le traitement dudit signal de sortie diffère.
PCT/JP2018/030189 2017-08-17 2018-08-13 Dispositif de mesure WO2019035441A1 (fr)

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TWI749531B (zh) * 2020-04-22 2021-12-11 晉弘科技股份有限公司 掃描裝置以及光學同調斷層掃描系統
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