WO2014126401A1 - Procédé et dispositif de tomographie par interférence optique - Google Patents

Procédé et dispositif de tomographie par interférence optique Download PDF

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Publication number
WO2014126401A1
WO2014126401A1 PCT/KR2014/001194 KR2014001194W WO2014126401A1 WO 2014126401 A1 WO2014126401 A1 WO 2014126401A1 KR 2014001194 W KR2014001194 W KR 2014001194W WO 2014126401 A1 WO2014126401 A1 WO 2014126401A1
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Prior art keywords
signal
optical
light
reference light
optical signal
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PCT/KR2014/001194
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English (en)
Korean (ko)
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정지채
김지현
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고려대학교 산학협력단
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
    • A61B5/0062—Arrangements for scanning
    • A61B5/0066—Optical coherence imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
    • G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B1/00—Instruments for performing medical examinations of the interior of cavities or tubes of the body by visual or photographical inspection, e.g. endoscopes; Illuminating arrangements therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02055—Reduction or prevention of errors; Testing; Calibration
    • G01B9/02062—Active error reduction, i.e. varying with time
    • G01B9/02067—Active error reduction, i.e. varying with time by electronic control systems, i.e. using feedback acting on optics or light
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/0209—Low-coherence interferometers
    • G01B9/02091—Tomographic interferometers, e.g. based on optical coherence

Definitions

  • the present invention relates to an optical coherence tomography apparatus and method.
  • Optical coherence tomography is a device that photographs the inside of a living tissue and material in high resolution using light that is harmless to the human body.
  • OCT can take a high-resolution image of monolayers of minute portions in biological tissues and materials using sub-wavelength interference light sources, to sub-micron regions.
  • OCT is widely used in laser tomography, optical fiber sensor systems, or optical communication in medical imaging, and can be classified into frequency domain OCT and spectrum domain OCT according to principles and structures.
  • the spectral region OCT uses a broadband light source, and the broadband light source analyzes the image of the light reflected from the measuring object for each wavelength band by a spectrometer.
  • a line detector in the form of a CMOS (Complementary Oxide Semiconductor) camera or a Charge-Coupled Device (CCD) camera is used.
  • spectrometers are designed so that a specific wavelength of a broadband light source is mapped to a specific pixel of a CCD or CMOS camera, and the mapped wavelength-specific pixels are kept linear.
  • the spectral region OCT obtains depth information of a measurement object by Fourier transforming a pixel combination.
  • the OCT is an apparatus for obtaining an image by analyzing the interference pattern generated by the optical path difference between the reference signal and the sample signal (measurement signal), it is necessary to adjust the reference signal according to the situation.
  • Korean Patent No. 849193 (Occurity System of the Invention) installs a filter member on an optical path between a light source and a detector so as to process an image by allowing the light to leave a time difference for each spectrum, Using a filter member such as a Fabry-Perot filter to disclose a configuration for processing the image by advancing by the wavelength with a time difference before the light generated from the light source is split in the light splitter or reflected from the measurement skin and combined in the light splitter have.
  • a filter member such as a Fabry-Perot filter
  • the present invention is to solve the above-mentioned problems of the prior art, to provide an optical coherence tomography apparatus and method in which a reference signal stage capable of adjusting the reference light amount is implemented.
  • the light source for outputting light the light output from the light source is divided into a first optical signal and a second optical signal and output
  • an interferometer for feedback receiving and combining the measurement light signal corresponding to the first optical signal and the reference light signal corresponding to the second optical signal, and irradiating the measurement target with the first optical signal output through the interferometer.
  • An object measuring unit for feeding back the measurement light signal reflected from the measurement object to the interferometer, irradiating the second optical signal output through the interferometer to a reference mirror, and applying the reference light signal reflected from the reference mirror to the interferometer
  • a reference light generator for feeding back, measuring the interference signal strength of the measurement light signal and the reference light signal coupled through the interferometer
  • a reference light amount adjusting unit for controlling the incident angle of the second optical signal to the reference mirror or the reflection angle of the reference mirror to be changed based on the photodetector and the previously measured interference signal strength.
  • an optical coherence tomography method using an optical coherence tomography apparatus comprises: (a) dividing and outputting light output from a light source into a first optical signal and a second optical signal, and (b) the Irradiating a first optical signal to a measurement object and irradiating the second optical signal to a reference mirror, (c) a measurement light signal in which the first optical signal is reflected from the measurement object, and the second optical signal is the reference mirror Receiving feedback of the reference light signal reflected from each other, (d) combining the fed back measurement light signal and reference light signal, and (e) measuring interference signal strength based on the combined measurement light signal and reference light signal Wherein the step (b) includes the incident angle of the second optical signal into the reference mirror or the reflection angle from the reference mirror set based on the interference signal strength previously measured. Apply the second optical signal.
  • the sensitivity of the tomography image can be improved to provide a clear tomography image.
  • any one of the problem solving means of the present invention it is possible to implement the reference light signal stage without a separate filter member can reduce the volume of the optical coherence tomography apparatus, and optimize the reference light signal irrespective of the blocking coefficient for each light wavelength can do.
  • any one of the problem solving means of the present invention by using the interference signal strength detected in real time, by actively changing the intensity of the next reference light signal, it is possible to quickly process the optimal tomography for the measurement object. .
  • FIG. 1 is a block diagram showing the configuration of an optical coherence tomography apparatus according to an embodiment of the present invention.
  • FIG. 2 is a block diagram showing the configuration of the reference light amount adjusting unit according to an embodiment of the present invention.
  • FIG. 3 is a block diagram showing the configuration of the reference light amount adjusting unit according to another embodiment of the present invention.
  • FIG. 4 is a block diagram showing the configuration of the reference light amount adjusting unit according to another embodiment of the present invention.
  • 5 is an example showing the spectrum of the interference signal strength according to the reference light amount control in an embodiment of the present invention.
  • FIG. 6 is an example showing a normalized light amount map for a reference light signal according to an embodiment of the present invention.
  • FIG. 7 is an example of a tomography image for explaining an effect of adjusting the amount of light of a reference light signal according to an embodiment of the present invention.
  • FIG. 8 is a flowchart illustrating a method for optical coherence tomography according to an exemplary embodiment of the present invention.
  • FIG. 1 is a configuration diagram showing the configuration of an optical coherence tomography apparatus according to an embodiment of the present invention.
  • the optical coherence tomography apparatus 100 includes a light source 110, an interferometer 120, an object measuring unit 130, a reference light generating unit 140, a reference mirror 150, and a photodetector ( 160, a reference light amount adjusting unit 170, and a tomography image processing unit 180.
  • the light source 110 outputs light for optical coherence tomography to the interferometer 120.
  • the interferometer 120 splits the light output from the light source 110 into a first optical signal and a second optical signal.
  • the interferometer 120 outputs the first optical signal toward the measurement object through the target measurement unit 130, and outputs the second optical signal toward the reference mirror 150 through the reference light generator 140.
  • the interferometer 120 receives feedback of the measurement light signal corresponding to the first optical signal through the target measurement unit 130, and feedbacks the reference light signal corresponding to the second optical signal through the reference light generator 140.
  • the interferometer 120 combines the feedback light signal and the reference light signal and transmits the measured light signal to the photodetector 160.
  • the object measuring unit 130 irradiates the measurement object with the first optical signal output through the interferometer 120, and feeds back the measurement light signal reflected from the measurement object to the interferometer 120.
  • the target measuring unit 130 may include a first optical collimator (not shown) that collects the first optical signal output from the interferometer 120 and outputs the parallel optical light toward the measurement object.
  • the first optical collimator (not shown) may be configured as a scanning lens.
  • the reference light generator 140 radiates the second optical signal output through the interferometer 120 to the reference mirror 150, and feeds back the reference light signal reflected from the reference mirror 150 to the interferometer 120.
  • the reference light generator 140 may include a second optical collimator (not shown) that collects the second optical signal output from the interferometer 120 and outputs the parallel light toward the reference mirror 150.
  • the second optical collimator (not shown) may be configured as a focusing lens. For example, by configuring each lens of the first optical collimator and the second optical collimator as the same lens, tomography images can be easily obtained without separately matching the refractive indices between the reference light signal stage and the target measurement stage.
  • the photodetector 160 measures the interference signal strength of the measurement light signal and the reference light signal coupled through the interferometer 120, and measures the measured interference signal strength with the tomographic image processor 180 and the reference light amount controller 170. send.
  • the tomography image processor 180 processes and processes the value of the interference signal strength measured by the photodetector 160 in a preset manner to generate and provide a tomography image of the measurement object.
  • the tomography image processor 180 extracts depth information according to the interference signal intensity value of the measurement object scanned by the target measurement unit 130, and collects a predetermined number of depth information for each pixel to obtain a tomography image.
  • the tomography image processing unit 180 extracts depth information by performing inverse Fourier transform after performing equal-space k-spatial conversion of the values of the interference signal strengths acquired through the photodetector 160 with respect to a predetermined wavelength.
  • the optical interference tomography apparatus 100 adjusts the magnitude of the reference light signal fed back through the reference light generator 140, and thus the signal-to-noise ratio of the tomography image. ) And improve the sensitivity.
  • the photodetector 160 includes a photographing means (eg, a camera) including an optical sensor. If the amount of light of the measurement light signal and the reference light signal received by the photodetector 160 through the interferometer 120 is too strong, the light sensor of the photodetector 160 is in a state of light saturation (that is, the interference signal Strength) can be difficult to measure. In addition, when the amount of light of the measurement light signal and the reference light signal received by the photodetector 160 is too weak, the signal-to-noise ratio and the sensitivity of the interference signal may be reduced, resulting in deterioration of the tomography image.
  • a photographing means eg, a camera
  • the light sensor of the photodetector 160 is in a state of light saturation (that is, the interference signal Strength) can be difficult to measure.
  • the signal-to-noise ratio and the sensitivity of the interference signal may be reduced, resulting in deterioration of the tomography image.
  • the reference light amount adjusting unit 170 is based on the previously measured interference signal strength (hereinafter referred to as 'previous interference signal strength') of the incident angle of the second optical signal to the reference mirror 150 or the reference mirror 150 Control the reflection angle with respect to the second optical signal.
  • 'previous interference signal strength' previously measured interference signal strength
  • the reference light amount adjusting unit 170 determines the target intensity of the reference light signal based on the photosaturation threshold of the photodetector 160 and the previous interference signal strength received from the photodetector 160.
  • the reference light amount adjusting unit 170 changes the incident angle of the second optical signal to the reference mirror 150 or the reflection angle of the reference mirror 150 with respect to the second optical signal based on the determined target intensity of the reference light signal.
  • the reference light amount adjusting unit 170 may set the initial value of the interference signal strength according to the measurement light signal and the reference light signal first fed back to the interferometer 120 with respect to the measurement object as the previous interference signal strength.
  • the optical interference tomography apparatus 100 before the optical interference tomography apparatus 100 measures the effective interference signal intensity for generating the tomographic image of the measurement object, the optical interference tomography apparatus 100 first performs a test step of determining the optimal reference light signal strength for the photodetector 150. To perform. Accordingly, in the state where the incident angle of the second optical signal set based on the optimal reference light signal intensity (that is, the target intensity) to the reference mirror 150 or the reflection angle of the reference mirror 150 with respect to the second optical signal is applied, A reference light signal can be obtained.
  • the optimal reference light signal intensity that is, the target intensity
  • Figure 2 is a block diagram showing the configuration of the reference light amount adjusting unit according to an embodiment of the present invention.
  • the reference light amount adjusting unit 170 includes the optical systems 171 and 172 and the optical system driver 173.
  • the optical systems 171 and 172 reflect the second optical signal output through the reference light generator 140 toward the reference mirror 150 at a predetermined reflection angle, respectively, to adjust the incident angle to the reference mirror 150.
  • the reference light amount adjusting unit 170 is reflected from the first optical system 171 and the first optical system for reflecting the second optical signal output in the first travel direction in a second travel direction different from the first travel direction. It includes a second optical system 172 for reflecting the optical signal in the first travel direction to enter the reference mirror 150.
  • Such a plurality of optical systems are opposed to each other so that light reflected from any one of the other optical systems is incident.
  • the reference light amount adjusting unit 170 includes two optical systems 171 and 172, but the reference light amount adjusting unit 170 may include one or more optical systems.
  • the optical system driver 173 sets the reflection angle for each optical system based on the plurality of optical systems 171 and 172 and the previous interference signal strength, and rotates the optical system driver 173 based on the reflection angle for each optical system.
  • the optical system driver 173 determines the target intensity of the reference light signal based on the previous interference signal strength, and sets the reflection angles of the first and second optical systems 171 and 172 according to the target intensity of the reference light signal. do.
  • FIG. 3 is a block diagram showing the configuration of the reference light amount adjusting unit according to another embodiment of the present invention.
  • the reference light amount adjusting unit 170 includes an optical collimator driver 174 that controls the second optical signal output angle of the reference light generating unit 140.
  • the optical collimator driver 174 sets the optical output angle of the reference light generator 140 (that is, the optical output angle of the second optical collimator (not shown)) based on the previous interference signal strength, and sets the set optical output. Based on the angle, the second optical collimator (not shown) is rotated in a set direction and angle.
  • the optical collimator driver 174 determines the target intensity of the reference light signal based on the previous interference signal strength as described above, and sets the optical output angle of the second optical collimator (not shown) according to the target intensity of the reference light signal. do.
  • FIG. 4 is a block diagram showing the configuration of the reference light amount adjusting unit according to another embodiment of the present invention.
  • the reference light amount adjusting unit 170 includes a reference mirror driving unit 175.
  • the reference mirror driver 175 sets the reflection angle of the reference mirror 150 based on the previous interference signal strength, and rotates the reference mirror 150 in the set direction and angle based on the set reflection angle.
  • the reference mirror driver 175 determines the target intensity of the reference light signal based on the previous interference signal strength, and sets the reflection angle of the reference mirror 150 according to the target intensity of the reference light signal.
  • the reference light amount adjusting unit 170 is fed back through the reference light generating unit 140 by adjusting the incident angle of the second optical signal incident on the reference mirror 150 or the reflection angle of the second optical signal of the reference mirror 150. The amount of light of the reference light signal is changed.
  • FIG. 5 is an example showing the spectrum of the interference signal strength according to the reference light amount control in the embodiment of the present invention.
  • FIG. 5 the light quantity spectrum of the interference signal acquired by the photodetector 160 according to the change in the light amount of the reference light signal is shown, and it can be seen that the interference signal intensity is different as the light amount of the reference light signal is changed.
  • the reference light amount adjusting unit 170 is applied to the incident angle of the second optical signal to the reference mirror 150 or to the second optical signal of the reference mirror 150.
  • a reference generation unit (not shown) may be further provided to provide setting criteria to accurately and quickly determine the angle of reflection for the target.
  • the reference generator (not shown) matches the reference light by matching at least one of the incident angle of the second optical signal to the reference mirror 150 and the reflection angle of the reference mirror 150 with respect to the second optical signal for each reference light signal intensity. Generate and store a normalized light quantity map for the signal.
  • FIG. 6 is an example showing a normalized light amount map for a reference light signal according to an embodiment of the present invention.
  • the reference light amount adjusting unit 170 may detect the incident angle or the reflection angle matching the target intensity of the reference light signal from the normalized light amount map generated and stored by the reference generator (not shown).
  • Such a reference generation unit may be included in the optical interference tomography apparatus 100 described above with reference to FIG. 1 as a configuration, and the reference light amount adjusting unit 170 is a self-contained reference generation unit (not shown). It is also possible to perform the operation.
  • the optical coherence tomography apparatus 100 actively changes and changes the intensity of the reference light signal by using the interference signal intensity detected in real time, thereby providing optimal tomography for the measurement object. Can be processed quickly.
  • FIG. 7 is an example of a tomography image for explaining a light amount control effect of a reference light signal according to an embodiment of the present invention.
  • FIG. 7A is a tomography image of a measurement object without adjusting the amount of light of the reference light signal
  • FIG. 7B shows an object to be measured by applying an optimal amount of light of the reference light signal set according to the interference signal strength measured in advance. It is a tomography image taken.
  • the sensitivity of the tomography image may be improved to provide a clear tomography image.
  • FIG. 8 is a flowchart illustrating a method for optical coherence tomography according to an embodiment of the present invention.
  • the target intensity of the reference light signal suitable for the light saturation threshold value of the photodetector of the optical interference tomography apparatus is determined (S110).
  • the reference light signal prior to acquiring the next measurement light signal and the reference light signal in the tomography of the measurement object, the reference light signal based on the previous interference signal intensity and the light saturation threshold measured based on the previous measurement light signal and the reference light signal. To determine the target strength.
  • the light saturation threshold may be set to the light saturation of the light sensor in the photodetector, and assuming that the light saturation of the light sensor is 100%, the target intensity of the reference light signal is 90% or less of the light saturation. Can be set.
  • the previous interference signal strength may be an initial value of the interference signal strength according to the measurement light signal and the reference light signal first fed back to the measurement object.
  • the incident angle of light with respect to the reference mirror of the optical interference tomography apparatus or the light reflection angle of the reference mirror is set and applied based on the determined target intensity of the reference light signal (S120).
  • the angle of incidence of the light with respect to the reference mirror may be changed by controlling the driving of a plurality of optical systems positioned between the interferometer and the reference mirror of the optical coherence tomography apparatus and changing the traveling path and angle of the light output through the interferometer.
  • the incident angle of the light to the reference mirror may be changed by controlling the driving of the optical collimator for outputting the light output through the interferometer at a set output angle.
  • the reflection angle of the reference mirror may be changed by controlling the driving of the reference mirror itself.
  • the normalized light amount map for the reference light signal to generate a normalized light amount map for the reference light signal by matching the incident angle of the optical signal to the reference mirror or the reflection angle for the optical signal of the reference mirror in advance for each reference light signal intensity Can be.
  • the incident angle or the reflection angle matched to the target intensity of the reference light signal may be quickly detected using the normalized light amount map in step S120.
  • the light output from the light source is divided into a first optical signal and a second optical signal through an interferometer and outputs (S130).
  • the target measuring unit of the optical coherence tomography apparatus irradiates the first optical signal to the measurement object
  • the reference light generating unit irradiates the second optical signal to the reference mirror (S140).
  • the second optical signal is irradiated to the reference mirror in a state in which the incident angle of light with respect to the reference mirror or the light reflection angle of the reference mirror is applied in step S120.
  • the interferometer receives feedback of the measurement light signal reflected from the measurement object through the target measurement unit, and receives the reference light signal reflected from the reference mirror through the reference light generator (S150).
  • the interference signal intensity based on the measured light signal and the reference light signal is measured through the photodetector of the optical coherence tomography apparatus (S160).
  • the step (S110) of determining the target intensity of the reference light signal is applied to the initial value of the interference signal intensity once or based on the previous interference signal every tomography. It is possible to apply.
  • Embodiments of the present invention may also be implemented in the form of a recording medium containing instructions executable by a computer, such as a program module executed by the computer.
  • Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media.
  • Computer readable media may include both computer storage media and communication media.
  • Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data.
  • Communication media typically includes computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transmission mechanism, and includes any information delivery media.
  • FIG. 1 is a configuration diagram showing the configuration of an optical coherence tomography apparatus according to an embodiment of the present invention.
  • the optical coherence tomography apparatus 100 includes a light source 110, an interferometer 120, an object measuring unit 130, a reference light generating unit 140, a reference mirror 150, and a photodetector ( 160, a reference light amount adjusting unit 170, and a tomography image processing unit 180.
  • the light source 110 outputs light for optical coherence tomography to the interferometer 120.
  • the interferometer 120 splits the light output from the light source 110 into a first optical signal and a second optical signal.
  • the interferometer 120 outputs the first optical signal toward the measurement object through the target measurement unit 130, and outputs the second optical signal toward the reference mirror 150 through the reference light generator 140.
  • the interferometer 120 receives feedback of the measurement light signal corresponding to the first optical signal through the target measurement unit 130, and feedbacks the reference light signal corresponding to the second optical signal through the reference light generator 140.
  • the interferometer 120 combines the feedback light signal and the reference light signal and transmits the measured light signal to the photodetector 160.
  • the object measuring unit 130 irradiates the measurement object with the first optical signal output through the interferometer 120, and feeds back the measurement light signal reflected from the measurement object to the interferometer 120.
  • the target measuring unit 130 may include a first optical collimator (not shown) that collects the first optical signal output from the interferometer 120 and outputs the parallel optical light toward the measurement object.
  • the first optical collimator (not shown) may be configured as a scanning lens.
  • the reference light generator 140 radiates the second optical signal output through the interferometer 120 to the reference mirror 150, and feeds back the reference light signal reflected from the reference mirror 150 to the interferometer 120.
  • the reference light generator 140 may include a second optical collimator (not shown) that collects the second optical signal output from the interferometer 120 and outputs the parallel light toward the reference mirror 150.
  • the second optical collimator (not shown) may be configured as a focusing lens. For example, by configuring each lens of the first optical collimator and the second optical collimator as the same lens, tomography images can be easily obtained without separately matching the refractive indices between the reference light signal stage and the target measurement stage.
  • the photodetector 160 measures the interference signal strength of the measurement light signal and the reference light signal coupled through the interferometer 120, and measures the measured interference signal strength with the tomographic image processor 180 and the reference light amount controller 170. send.
  • the tomography image processor 180 processes and processes the value of the interference signal strength measured by the photodetector 160 in a preset manner to generate and provide a tomography image of the measurement object.
  • the tomography image processor 180 extracts depth information according to the interference signal intensity value of the measurement object scanned by the target measurement unit 130, and collects a predetermined number of depth information for each pixel to obtain a tomography image.
  • the tomography image processing unit 180 extracts depth information by performing inverse Fourier transform after performing equal-space k-spatial conversion of the values of the interference signal strengths acquired through the photodetector 160 with respect to a predetermined wavelength.
  • the optical interference tomography apparatus 100 adjusts the magnitude of the reference light signal fed back through the reference light generator 140, and thus the signal-to-noise ratio of the tomography image. ) And improve the sensitivity.
  • the photodetector 160 includes a photographing means (eg, a camera) including an optical sensor. If the amount of light of the measurement light signal and the reference light signal received by the photodetector 160 through the interferometer 120 is too strong, the light sensor of the photodetector 160 is in a state of light saturation (that is, the interference signal Strength) can be difficult to measure. In addition, when the amount of light of the measurement light signal and the reference light signal received by the photodetector 160 is too weak, the signal-to-noise ratio and the sensitivity of the interference signal may be reduced, resulting in deterioration of the tomography image.
  • a photographing means eg, a camera
  • the light sensor of the photodetector 160 is in a state of light saturation (that is, the interference signal Strength) can be difficult to measure.
  • the signal-to-noise ratio and the sensitivity of the interference signal may be reduced, resulting in deterioration of the tomography image.
  • the reference light amount adjusting unit 170 is based on the previously measured interference signal strength (hereinafter referred to as 'previous interference signal strength') of the incident angle of the second optical signal to the reference mirror 150 or the reference mirror 150 Control the reflection angle with respect to the second optical signal.
  • 'previous interference signal strength' previously measured interference signal strength
  • the reference light amount adjusting unit 170 determines the target intensity of the reference light signal based on the photosaturation threshold of the photodetector 160 and the previous interference signal strength received from the photodetector 160.
  • the reference light amount adjusting unit 170 changes the incident angle of the second optical signal to the reference mirror 150 or the reflection angle of the reference mirror 150 with respect to the second optical signal based on the determined target intensity of the reference light signal.
  • the reference light amount adjusting unit 170 may set the initial value of the interference signal strength according to the measurement light signal and the reference light signal first fed back to the interferometer 120 with respect to the measurement object as the previous interference signal strength.
  • the optical interference tomography apparatus 100 before the optical interference tomography apparatus 100 measures the effective interference signal intensity for generating the tomographic image of the measurement object, the optical interference tomography apparatus 100 first performs a test step of determining the optimal reference light signal strength for the photodetector 150. To perform. Accordingly, in the state where the incident angle of the second optical signal set based on the optimal reference light signal intensity (that is, the target intensity) to the reference mirror 150 or the reflection angle of the reference mirror 150 with respect to the second optical signal is applied, A reference light signal can be obtained.
  • the optimal reference light signal intensity that is, the target intensity
  • Figure 2 is a block diagram showing the configuration of the reference light amount adjusting unit according to an embodiment of the present invention.
  • the reference light amount adjusting unit 170 includes the optical systems 171 and 172 and the optical system driver 173.
  • the optical systems 171 and 172 reflect the second optical signal output through the reference light generator 140 toward the reference mirror 150 at a predetermined reflection angle, respectively, to adjust the incident angle to the reference mirror 150.
  • the reference light amount adjusting unit 170 is reflected from the first optical system 171 and the first optical system for reflecting the second optical signal output in the first travel direction in a second travel direction different from the first travel direction. It includes a second optical system 172 for reflecting the optical signal in the first travel direction to enter the reference mirror 150.
  • Such a plurality of optical systems are opposed to each other so that light reflected from any one of the other optical systems is incident.
  • the reference light amount adjusting unit 170 includes two optical systems 171 and 172, but the reference light amount adjusting unit 170 may include one or more optical systems.
  • the optical system driver 173 sets the reflection angle for each optical system based on the plurality of optical systems 171 and 172 and the previous interference signal strength, and rotates the optical system driver 173 based on the reflection angle for each optical system.
  • the optical system driver 173 determines the target intensity of the reference light signal based on the previous interference signal strength, and sets the reflection angles of the first and second optical systems 171 and 172 according to the target intensity of the reference light signal. do.
  • FIG. 3 is a block diagram showing the configuration of the reference light amount adjusting unit according to another embodiment of the present invention.
  • the reference light amount adjusting unit 170 includes an optical collimator driver 174 that controls the second optical signal output angle of the reference light generating unit 140.
  • the optical collimator driver 174 sets the optical output angle of the reference light generator 140 (that is, the optical output angle of the second optical collimator (not shown)) based on the previous interference signal strength, and sets the set optical output. Based on the angle, the second optical collimator (not shown) is rotated in a set direction and angle.
  • the optical collimator driver 174 determines the target intensity of the reference light signal based on the previous interference signal strength, and sets the optical output angle of the second optical collimator (not shown) according to the target intensity of the reference light signal. do.
  • FIG. 4 is a block diagram showing the configuration of the reference light amount adjusting unit according to another embodiment of the present invention.
  • the reference light amount adjusting unit 170 includes a reference mirror driving unit 175.
  • the reference mirror driver 175 sets the reflection angle of the reference mirror 150 based on the previous interference signal strength, and rotates the reference mirror 150 in the set direction and angle based on the set reflection angle.
  • the reference mirror driver 175 determines the target intensity of the reference light signal based on the previous interference signal strength, and sets the reflection angle of the reference mirror 150 according to the target intensity of the reference light signal.
  • the reference light amount adjusting unit 170 is fed back through the reference light generating unit 140 by adjusting the incident angle of the second optical signal incident on the reference mirror 150 or the reflection angle of the second optical signal of the reference mirror 150. The amount of light of the reference light signal is changed.
  • FIG. 5 is an example showing the spectrum of the interference signal strength according to the reference light amount control in the embodiment of the present invention.
  • FIG. 5 the light quantity spectrum of the interference signal acquired by the photodetector 160 according to the change in the light amount of the reference light signal is shown, and it can be seen that the interference signal intensity is different as the light amount of the reference light signal is changed.
  • the reference light amount adjusting unit 170 is applied to the incident angle of the second optical signal to the reference mirror 150 or to the second optical signal of the reference mirror 150.
  • a reference generation unit (not shown) may be further provided to provide setting criteria to accurately and quickly determine the angle of reflection for the target.
  • the reference generator (not shown) matches the reference light by matching at least one of the incident angle of the second optical signal to the reference mirror 150 and the reflection angle of the reference mirror 150 with respect to the second optical signal for each reference light signal intensity. Generate and store a normalized light quantity map for the signal.
  • FIG. 6 is an example showing a normalized light amount map for a reference light signal according to an embodiment of the present invention.
  • the reference light amount adjusting unit 170 may detect the incident angle or the reflection angle matching the target intensity of the reference light signal from the normalized light amount map generated and stored by the reference generator (not shown).
  • Such a reference generation unit may be included in the optical interference tomography apparatus 100 described above with reference to FIG. 1 as a configuration, and the reference light amount adjusting unit 170 is a self-contained reference generation unit (not shown). It is also possible to perform the operation.
  • the optical coherence tomography apparatus 100 actively changes and changes the intensity of the reference light signal by using the interference signal intensity detected in real time, thereby providing optimal tomography for the measurement object. Can be processed quickly.
  • FIG. 7 is an example of a tomography image for explaining a light amount control effect of a reference light signal according to an embodiment of the present invention.
  • FIG. 7A is a tomography image of a measurement object without adjusting the amount of light of the reference light signal
  • FIG. 7B shows an object to be measured by applying an optimal amount of light of the reference light signal set according to the interference signal strength measured in advance. It is a tomography image taken.
  • the sensitivity of the tomography image may be improved to provide a clear tomography image.
  • FIG. 8 is a flowchart illustrating a method for optical coherence tomography according to an embodiment of the present invention.
  • the target intensity of the reference light signal suitable for the light saturation threshold value of the photodetector of the optical interference tomography apparatus is determined (S110).
  • the reference light signal prior to acquiring the next measurement light signal and the reference light signal in the tomography of the measurement object, the reference light signal based on the previous interference signal intensity and the light saturation threshold measured based on the previous measurement light signal and the reference light signal. To determine the target strength.
  • the light saturation threshold may be set to the light saturation of the light sensor in the photodetector, and assuming that the light saturation of the light sensor is 100%, the target intensity of the reference light signal is 90% or less of the light saturation. Can be set.
  • the previous interference signal strength may be an initial value of the interference signal strength according to the measurement light signal and the reference light signal first fed back to the measurement object.
  • the incident angle of light with respect to the reference mirror of the optical interference tomography apparatus or the light reflection angle of the reference mirror is set and applied based on the determined target intensity of the reference light signal (S120).
  • the angle of incidence of the light with respect to the reference mirror may be changed by controlling the driving of a plurality of optical systems positioned between the interferometer and the reference mirror of the optical coherence tomography apparatus and changing the traveling path and angle of the light output through the interferometer.
  • the incident angle of the light to the reference mirror may be changed by controlling the driving of the optical collimator for outputting the light output through the interferometer at a set output angle.
  • the reflection angle of the reference mirror may be changed by controlling the driving of the reference mirror itself.
  • the normalized light amount map for the reference light signal to generate a normalized light amount map for the reference light signal by matching the incident angle of the optical signal to the reference mirror or the reflection angle for the optical signal of the reference mirror in advance for each reference light signal intensity Can be.
  • the incident angle or the reflection angle matched to the target intensity of the reference light signal may be quickly detected using the normalized light amount map in step S120.
  • the light output from the light source is divided into a first optical signal and a second optical signal through an interferometer and outputs (S130).
  • the target measuring unit of the optical coherence tomography apparatus irradiates the first optical signal to the measurement object
  • the reference light generating unit irradiates the second optical signal to the reference mirror (S140).
  • the second optical signal is irradiated to the reference mirror in a state in which the incident angle of light with respect to the reference mirror or the light reflection angle of the reference mirror is applied in step S120.
  • the interferometer receives feedback of the measurement light signal reflected from the measurement object through the target measurement unit, and receives the reference light signal reflected from the reference mirror through the reference light generator (S150).
  • the interference signal intensity based on the measured light signal and the reference light signal is measured through the photodetector of the optical coherence tomography apparatus (S160).
  • the step (S110) of determining the target intensity of the reference light signal is applied to the initial value of the interference signal intensity once or based on the previous interference signal every tomography. It is possible to apply.
  • Embodiments of the present invention may also be implemented in the form of a recording medium containing instructions executable by a computer, such as a program module executed by the computer.
  • Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media.
  • Computer readable media may include both computer storage media and communication media.
  • Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data.
  • Communication media typically includes computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transmission mechanism, and includes any information delivery media.

Abstract

Le procédé de tomographie par interférence optique comprend les étapes consistant à : diviser la sortie de lumière d'une source lumineuse en un premier et un deuxième signal optique; irradier un objet mesuré avec le premier signal optique, et irradier un miroir de référence avec le deuxième signal optique; renvoyer le signal optique de mesure obtenu à partir du premier signal optique réfléchi par l'objet mesuré et le signal optique de référence obtenu à partir du deuxième signal optique réfléchi par le miroir de référence; combiner le signal optique de mesure et le signal optique de référence; et mesurer l'intensité d'un signal d'interférence sur la base de la combinaison du signal optique de mesure et de référence, lequel second signal optique est irradié sur le miroir de référence en appliquant l'angle d'incidence et l'angle de réflexion du second signal optique établi sur la base de l'intensité du signal d'interférence précédemment mesurée.
PCT/KR2014/001194 2013-02-13 2014-02-13 Procédé et dispositif de tomographie par interférence optique WO2014126401A1 (fr)

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JP2000283912A (ja) * 1999-03-30 2000-10-13 Biophotonics Information Laboratories Ltd 光学的断層像撮影装置
JP2009072280A (ja) * 2007-09-19 2009-04-09 Fujifilm Corp 光断層画像化装置、接触領域検出方法及びそれを用いた画像処理方法
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