WO2019062484A1 - 一种光学相干断层扫描成像系统 - Google Patents

一种光学相干断层扫描成像系统 Download PDF

Info

Publication number
WO2019062484A1
WO2019062484A1 PCT/CN2018/103869 CN2018103869W WO2019062484A1 WO 2019062484 A1 WO2019062484 A1 WO 2019062484A1 CN 2018103869 W CN2018103869 W CN 2018103869W WO 2019062484 A1 WO2019062484 A1 WO 2019062484A1
Authority
WO
WIPO (PCT)
Prior art keywords
arm
fiber coupler
port
reference arm
length
Prior art date
Application number
PCT/CN2018/103869
Other languages
English (en)
French (fr)
Inventor
卫星
黄炳杰
陈军
彭先兆
Original Assignee
视微影像(河南)科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 视微影像(河南)科技有限公司 filed Critical 视微影像(河南)科技有限公司
Publication of WO2019062484A1 publication Critical patent/WO2019062484A1/zh
Priority to US16/831,842 priority Critical patent/US11022424B2/en

Links

Images

Classifications

    • 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
    • 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
    • A61B3/0016—Operational features thereof
    • 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
    • A61B3/102—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for optical coherence tomography [OCT]
    • 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
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
    • 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
    • G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
    • G01B9/02002—Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies
    • G01B9/02004—Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies using frequency scans
    • 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
    • G01B9/02015—Interferometers characterised by the beam path configuration
    • G01B9/02027—Two or more interferometric channels or 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
    • G01B9/02056—Passive reduction of errors
    • G01B9/02059—Reducing effect of parasitic reflections, e.g. cyclic errors

Definitions

  • the invention relates to three-dimensional imaging technology, in particular to a frequency-sweep source optical coherence tomography (OCT) system.
  • OCT optical coherence tomography
  • OCT optical coherence tomography
  • OCT technology has the advantages of high resolution, fast imaging speed and high sensitivity. Since the first commercial OCT imaging device was introduced in 1996, OCT technology has greatly promoted the development of ophthalmic diagnostics. In the past two decades, with the continuous updating of technology, the imaging speed, sensitivity, resolution and imaging depth of OCT technology are also constantly improving.
  • the Swept Source OCT also known as SS-OCT.
  • the SS-OCT uses a fast swept laser as the light source.
  • commercial ophthalmic SS-OCT equipment Carl Zeiss, PLEX Elite 9000
  • FDA US Food and Drug Administration
  • the most commonly used OCT equipment in the field of ophthalmic diagnosis is OCT based on frequency domain technology, which is called frequency domain OCT or SD-OCT.
  • FIG. 1 is a schematic diagram of a system of SD-OCT
  • FIG. 2 is a schematic diagram of a system of SS-OCT.
  • the core of SD-OCT and SS-OCT is an optical interferometric system, which includes a sample arm (abbreviated as SMP in the figure) and a reference arm (abbreviated as REF in the figure), and records the interferometric optical frequency signal.
  • the reference arm includes an adjustable optical delay arm for adjusting the optical path of the reference arm to match the optical path of the sample arm.
  • SD-OCT uses Low Coherence Source (LCS in Figure 1) and uses a spectrometer (generally composed of diffraction grating and one-dimensional line scan camera).
  • spectrometer generally composed of diffraction grating and one-dimensional line scan camera.
  • Interferometric spectral signals SS-OCT uses a swept source and uses high-speed photodetectors to acquire interferometric signals.
  • DSP digital signal processing unit
  • the interference system employed in Figures 1 and 2 is a Michelson interferometer.
  • Figure 3 uses the Mach-Zehnder interferometer system.
  • Coupler 1 is the first coupler
  • Coupler 2 is the second coupler
  • Sample Arm represents the sample arm
  • Reference Arm represents the reference arm
  • A' direction is the return light of the sample arm
  • B' direction is the return of the reference arm.
  • Light, the return light of the sample arm and the return light of the reference arm interfere at the second coupler Coupler 2 and are detected by the balance detector Balanced Detector.
  • FIG. 3 omits the scanning device for the sample to be tested in the sample arm.
  • the sample to be tested in Figure 3 is an eye, but the description herein is not limited to the application of ophthalmology.
  • the imaging depth of SD-OCT and SS-OCT is limited by different system parameters.
  • the imaging depth of the SD-OCT is determined by the spectrometer resolution, which is approximately a few millimeters in the air medium; the SS-OCT imaging depth is determined by the coherence length of the swept source, the spectral signal detector bandwidth, and the sampling frequency.
  • the imaging depth is usually a few millimeters. The deepest can reach hundreds of millimeters.
  • SD-OCT has become more and more mature.
  • most of the low-coherence light sources used in SD-OCT are superluminescent light-emitting diodes (SLDs).
  • SLD has the characteristics of high stability and low price.
  • SS-OCT has the advantages of faster imaging, deeper and higher sensitivity, and is likely to replace SD-OCT.
  • the sweep source has a single longitudinal mode output laser and a multi-longitudinal mode output laser.
  • a single longitudinal mode laser with continuously adjustable optical frequency is more ideal for SS-OCT.
  • the current market has matured and commercialized sweeping sources based on multiple longitudinal modes.
  • multi-longitudinal mode lasers although the spectral envelope of the output appears to be continuous, in reality the comb-like spectral lines appear in the spectral envelope due to the presence of multiple longitudinal modes.
  • the difference frequency of two adjacent longitudinal modes is determined by the length of the laser cavity in the swept source.
  • the coherent reproduction effect itself is not necessarily harmful.
  • researchers can use the coherent recurrence effect to increase the imaging depth of OCT. This technique is called coherence revival multiplexing.
  • the coherent reproduction effect has a more serious side effect.
  • the coherent reproduction effect creates artifacts in the OCT image.
  • a strong optical interference signal can be obtained only when the optical path difference between the sample arm and the reference arm is smaller than the imaging depth of the system; for an optical signal with an optical path difference greater than the imaging depth, it is not observed.
  • strong interference is formed due to the coherent reproduction effect. Therefore, artifacts caused by reflection or scattering of components in the optical path are more likely to occur in SS-OCT. This is one of the technical difficulties that limit the further development of SS-OCT.
  • a method for suppressing the reverse signal generally used in a fiber optic system is to use an optical Isolator.
  • ring-shaped optical isolators are difficult to achieve sufficient spectral width, are expensive, and are prone to cause additional optical loss and polarization mode dispersion (PMD), thereby reducing system sensitivity.
  • PMD polarization mode dispersion
  • Methods for avoiding coherent reproduction artifacts also include the use of frequency domain mode-locked (FDML) laser sources and single longitudinal mode laser sources (such as vertical cavity surface emitting laser VCSELs).
  • FDML frequency domain mode-locked
  • VCSELs vertical cavity surface emitting laser
  • the above circumvention method may not be applicable due to some specific limitations.
  • the above evasive method is not efficient enough.
  • Figure 4 is an SS-OCT system based on a Mach-Zehnder interferometer.
  • the return light A' of the sample arm and the return light B' of the reference arm interfere at the coupler H, and the interference signal is detected by the balance detector Balanced Detector.
  • the interference couplers commonly used in SS-OCT systems are based on fiber optic systems, the delay arms in the reference arms mostly use free-space optical systems.
  • the retarding arm typically includes a fiber end face (E and G in Figure 4), a collimator, and a reflective prism (F in Figure 4). These optical components are likely to produce parasitic reflections. These reflected signals, even if they are weak, are coupled back to the fiber optic system of the interferometer through the fiber end face E.
  • the dotted line in the figure represents the reflected signal C', passing through the path E and B ⁇ H at the coupler H and the reference.
  • the arm returns light B' to interfere.
  • the coherent reproduction artifacts resulting from the parasitic reflection of the delayed arm elements are thus easily aliased with the OCT structure image of the sample to be tested (D in Fig. 4), affecting the judgment of the real OCT structure image, as shown in Fig. 5. Since there are many components in the delay arm that can generate parasitic reflections, and the delay arm itself adjusts the optical path within a certain range, it is difficult for optical and system design to ensure all of these components (not limited to E and G in Figure 4).
  • the optical path difference between the reflected optical path and the sample to be tested can completely avoid the integral multiple of the laser cavity length of the swept source (A in Fig. 4).
  • OCT systems are based on the Michelson or Mach-Zehnder interferometer system.
  • the optical path of the sample arm and the optical path of the reference arm must be matched to obtain an optical interference signal.
  • FIG. 4 based on the Mach-Zehnder interferometer SS-OCT system, it is necessary to adjust the optical path of the delay arm so that the optical path length (OPL) of the sample arm and the reference arm are matched.
  • OPL optical path length
  • the present invention provides a design different from that of a common OCT system.
  • An optical coherence tomography (OCT) system including a frequency sweep laser, a Mach-Zehnder interferometer, and a balance detector;
  • the interferometer includes a first fiber coupler, a second fiber coupler, a sample arm, and Reference arm;
  • the reference arm includes a reference arm front section, a reference arm rear section, and a delay arm (in one embodiment the delay arm itself further includes a third fiber coupler);
  • each fiber coupler includes a first port, a second port a third port and a fourth port; an output end of the swept laser is coupled to the first port of the first fiber coupler, a second port of the first fiber coupler is coupled to the sample arm, and a third port of the first fiber coupler is coupled to the reference port
  • the front end of the arm, the fourth port of the first fiber coupler is coupled to the first port of the second fiber coupler; the end of the front end of the reference arm is coupled to the rear portion of the reference arm by a delay arm (in one embodiment the connection
  • the delay arm comprises an end face of the fiber, a collimator and a reflective optical element;
  • the end face of the fiber comprises an end face of the fiber of the front section of the reference arm and an end face of the end of the reference arm;
  • the collimator comprises an incident collimator and a reflection quasi
  • the reference light is reflected by the reflective optical element after entering the incident collimator through the front section of the reference arm;
  • the returned reference light is output to the second fiber coupler through the reflective collimator output to the reference arm rear section;
  • the length of the reference arm front section It is larger than the length of the sample arm, and the difference between the length of the reference arm front and the length of the sample arm is greater than 8 times the length of the swept source cavity.
  • the delay arm comprises an end face of the fiber, a collimator and a reflective optical element;
  • the end face of the fiber comprises an end face of the fiber of the front section of the reference arm and an end face of the end of the reference arm;
  • the collimator comprises an incident collimator and a reflection quasi The reference light is reflected by the reflective optical element after entering the incident collimator through the front section of the reference arm, and the returned reference light is outputted to the second fiber coupler via the reflective collimator to the reference arm rear end;
  • the reference arm front section and the delay arm are set
  • the sum of the length of the round trip is L, L is less than the length of the sample arm, and the difference between the sample arm and L is greater than 8 times the length of the swept source.
  • the collimator in the delay arm is a single collimator, and further includes a third fiber coupler common to the reference arm front section and the reference arm rear section; the reference arm front section is connected to the third fiber coupler a port; the second port of the third fiber coupler is connected to the single collimator; the reference light enters the single collimator and is returned by the reflective optical element and returned to the third port of the third fiber coupler; the third fiber
  • the third port of the coupler is connected to the second port of the second fiber coupler; the length of the front section of the reference arm is greater than the length of the sample arm, and the difference between the length of the reference arm front section and the sample arm is greater than the length of the swept source cavity Times.
  • the third fiber coupler has a fourth port that can be used for other experimental purposes, such as full laser power monitoring.
  • the collimator in the delay arm is a single collimator, and further includes a third fiber coupler, the third fiber coupler is commonly used for the reference arm front section and the reference arm rear section; the reference arm front section is connected to the third section.
  • a first port of the fiber coupler; a second port of the third fiber coupler is coupled to the single collimator; the reference light enters the single collimator and is reflected by the reflective optical element and returned to the third port of the third fiber coupler
  • the third port of the third fiber coupler is connected to the second port of the second fiber coupler; the sum of the length of the front end of the reference arm and the length of the extension arm is L, L is smaller than the length of the sample arm, and the difference between the sample arm and L The value is greater than 8 times the length of the swept source.
  • the reflective optical element is a Corner Reflector.
  • the optical coherence tomography imaging system improves the coherent reproduction artifact order by lengthening or shortening the optical path of the parasitic or stray reflected light of the delay arm element, thereby suppressing the coherent reproduction artifact Effect.
  • the optical coherence tomography imaging system can achieve sufficient spectral width, simple structure, low cost, no additional optical loss and polarization dispersion, and can ensure the sensitivity of the system.
  • Figure 1 is a schematic diagram of an SD-OCT system
  • FIG. 2 is a schematic diagram of an SS-OCT system
  • FIG. 3 is a schematic diagram of an SS-OCT system based on a Mach-Zehnder interferometer
  • Figure 5 is a schematic diagram of coherent reproduction artifacts due to parasitic reflection of a delay arm element
  • FIG. 6 is a schematic diagram of an SS-OCT system of Embodiment 1;
  • Figure 8 is a graph showing the relative signal strength variation of coherent reproduction artifacts of different orders
  • FIG. 9 is a schematic diagram of an SS-OCT system of Embodiment 2.
  • FIG. 10 is a schematic diagram of an SS-OCT system of Embodiment 3.
  • Figure 11 is a detailed view of the splitter ratio and optical power transmission of the coupler of the third embodiment
  • Figure 12 is an OCT image after suppression of coherent reproduction artifacts using the method of the present invention.
  • Embodiment 1 is a diagrammatic representation of Embodiment 1:
  • An optical coherence tomography imaging system comprising a swept laser 1, a balance detector 2, a Mach-Zehnder interferometer; the interferometer comprises a first fiber coupler 3, a second fiber coupler 4, a sample arm 5 and a reference arm;
  • the reference arm includes a reference arm front section 61, a reference arm rear section 62, and a delay arm 63;
  • the first fiber coupler 3 and the second fiber coupler 4 each include a first port, a second port, a third port, and a fourth port;
  • the output end of the frequency laser 1 is connected to the first port of the first fiber coupler 3;
  • the second port of the first fiber coupler 3 is connected to the sample arm 5;
  • the third port of the first fiber coupler 3 is connected to the front arm 61 of the reference arm;
  • the fourth port of a fiber coupler 3 is connected to the first port of the second fiber coupler 4;
  • the end of the reference arm front section 61 is connected to the reference arm rear section 62 via
  • the delay arm 63 includes an end face of the optical fiber, a collimator 631, and a reflective optical element 632 (in this embodiment, a corner cube prism), and the end face of the optical fiber includes a fiber end face 611 of the front end of the reference arm and a fiber end face 621 of the rear section of the reference arm;
  • the collimator 631 includes an incident collimator and a reflective collimator.
  • the reference light is reflected by the reflective optical element 632 after entering the incident collimator via the front arm 61 of the reference arm, and the returned reference light is output to the reference arm through the reflective collimator.
  • Segment 62 reaches second fiber coupler 4.
  • the length of the optical fiber of the back section 62 of the reference arm is lengthened, and the total optical path of the path B ⁇ E ⁇ F ⁇ G ⁇ H is kept unchanged.
  • the optical path OPL (B ⁇ E) of the reference arm front optical path will be much larger than the optical path optical path OPL (B ⁇ C ⁇ D) of the sample arm, and the optical path difference between them is L'.
  • L' should be greater than N times the length of the swept source cavity, and N is a positive integer. Experiments show that when N is greater than 8, the effect of coherent reproduction artifacts on the real OCT image structure can be ignored.
  • the experimental results of a particular swept source are shown in Figures 7 and 8.
  • the order symbol + in Figure 7 indicates that the sample arm optical path is greater than the reference arm optical path, and the order symbol - indicates that the sample arm optical path is smaller than the reference arm optical path.
  • the length of the swept laser cavity is 50 mm, and the difference between the length of the reference arm and the length of the sample arm should be greater than 400 mm. If the cavity length of the swept laser is 40 mm, the difference between the length of the reference arm and the length of the sample arm The value should be greater than 320mm, that is, the following conditions must be met:
  • Embodiment 2 is a diagrammatic representation of Embodiment 1:
  • the second embodiment differs from the first embodiment in that the second embodiment shortens the length of the optical fiber of the front section 61 of the reference arm by lengthening the length of the optical fiber of the reference section rear section 62, thereby achieving the same effect of suppressing coherent reproduction artifacts.
  • the rest of the system is the same as in the first embodiment.
  • the sum of the lengths of the reference arm front section 61 and the delay arm 63 is L, L is smaller than the length of the sample arm, and the difference between the sample arm and L is greater than 8 times of the length of the swept source. That is, the following conditions need to be met:
  • Embodiment 3 is a diagrammatic representation of Embodiment 3
  • the delay arm 63 in the third embodiment is different from the first embodiment and the second embodiment.
  • the collimator 631 in the delay arm 63 is a single collimator, and further includes a third fiber coupler 7 and a third fiber coupling.
  • the device 7 is commonly used for the reference arm front section and the reference arm rear section;
  • the third fiber coupler 7 includes a first port, a second port, and a third port;
  • the reference arm front section 61 is connected to the first port of the third fiber coupler 7,
  • the second port of the third fiber coupler 7 is connected to the single collimator, and the reference light enters the single collimator and is returned to the original path via the reflective optical element 632 (in this embodiment, using a corner cube prism) and then passed through the third fiber coupler 7
  • the third port of the third fiber coupler 7 is connected to the second port of the second fiber coupler 4.
  • the other parts are the same as those of the first embodiment and the second embodiment.
  • the optical path of the sample arm matches the optical path of the reference arm, which meets the following conditions.
  • the parasitic reflected light of the element in the delay arm is coupled back to the interference system via the reference arm front fiber end face 611, and returned to the second fiber coupler 4 and the reference arm by the third fiber coupler 7 and the first fiber coupler 3 . It is particularly pointed out that due to the presence of the third fiber coupler 7, the coupling efficiency of the parasitic reflected light is improved, and the coherent reproduction artifact intensity is also stronger.
  • the length of the reference arm front section 61 is greater than the length of the sample arm 5, and the difference between the length of the reference arm front section 61 and the sample arm 5 is greater than 8 times of the length of the swept source light source, that is, the following conditions are required to achieve the suppression of the coherent weight The purpose of the current artifact.
  • the sum of the lengths of the reference arm front section 61 and the delay arm 63 is L, L is smaller than the length of the sample arm 5, and the difference between the sample arms 5 and L is greater than 8 times the length of the scanning source cavity, that is:
  • the third embodiment of the present invention as shown in FIG. 10 simplifies the delay arm 63 compared to the first embodiment and the second embodiment because the delay arm design of the single collimator has better stability and more convenient assembly.
  • the third fiber coupler 7 has a fourth port G that can be used for other experimental purposes, such as laser power safety monitoring.
  • Figure 11 shows the splitter split ratio and optical power transfer details in the optical path.
  • the power calculation is simplified here, ignoring the coupling loss in the system, assuming that the reflection efficiency of the delay arm is 50%.
  • the coherent reproduction artifacts can be easily moved to more than 20 orders, much larger than the above-mentioned requirements above 8th order (the higher the order, the suppression of coherent reproduction) The better the effect of artifacts). It is assumed here that the frequency of the swept laser cavity is 50 mm, and the optical path of the optocoupler is negligible. In the calculation of OPL, the fiber refractive index of the group is about 1.47.
  • OPL(B ⁇ J ⁇ E)-OPL(B ⁇ C ⁇ D) ⁇ 4410-3090 1320mm ⁇ 26 ⁇ sweep laser cavity length
  • the swept source must be capable of allowing 1.3% of the optical power to be reflected back to the source.
  • the purpose is to lengthen or shorten the optical path of the light reflected by the delay arm element, so that the delay arm is parasitic or
  • the difference between the optical path of the stray reflected signal reaching the second fiber coupler and the optical path of the sample is greater than 8 times of the cavity length of the swept laser, thereby achieving the purpose of suppressing coherent reproduction artifacts.

Landscapes

  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Biomedical Technology (AREA)
  • Biophysics (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Radiology & Medical Imaging (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Signal Processing (AREA)
  • Pathology (AREA)
  • Ophthalmology & Optometry (AREA)
  • Artificial Intelligence (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Physiology (AREA)
  • Psychiatry (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

一种光学相干断层扫描成像系统，包括扫频激光器（1）、马赫-曾德式干涉仪、平衡探测器（2）；干涉仪包括第一光纤耦合器（3）、第二光纤耦合器（4）、样品臂（5）和参考臂；参考臂包括参考臂前段（61）、参考臂后段（62）及延迟臂（63）；参考臂前段（61）的末端通过延迟臂（63）与参考臂后段（62）连接；第一光纤耦合器（3）用于将扫频光源的输出光分为样品光和参考光，并将返回的样品光分配至第二光纤耦合器（4）；延迟臂（63）的寄生反射信号到达第二光纤耦合器（4）的光程与样品光光程的差值大于扫频激光器腔长的8倍，其可以抑制相干重现伪像，可以实现足够的光谱宽度，结构简单，成本较低，不会引起额外的光损耗和偏振色散，可以保证系统的灵敏度。

Description

一种光学相干断层扫描成像系统 技术领域
本发明涉及三维成像技术，尤其涉及一种扫频源光学相干断层扫描成像(OCT,Optical Coherence Tomography)系统。
背景技术
光学相干断层扫描成像(OCT)是一种三维成像技术，它具有广泛的应用领域，特别是生物医学成像。OCT技术具有高分辨率、成像速度快和灵敏度高等优点。自从1996年第一台商用OCT成像设备问世以来，OCT技术极大的推动了眼科诊断学的发展。近二十年来，随着技术不断的更新，OCT技术的成像速度、灵敏度、分辨率和成像深度也在不断进步。
目前，最先进的OCT技术是扫频源(Swept Source)OCT，也被称为SS-OCT。SS-OCT采用快速扫频激光器作为光源。2016年，商用眼科SS-OCT设备(卡尔蔡司，PLEX Elite 9000)通过了美国食品药品管理局(FDA)的认证审核。由于SS-OCT高昂的价格和复杂的系统设计，SS-OCT设备还没有在眼科诊断领域广泛使用。目前，眼科诊断领域最常用的OCT设备是基于频域技术的OCT，被称为频域OCT或者SD-OCT。
图1是SD-OCT的系统示意图，图2是SS-OCT的系统示意图。SD-OCT和SS-OCT的核心都是一个光学干涉系统，均包含样品臂(图中简写为SMP)和参考臂(图中简写为REF)，并记录干涉光频信号。通常，参考臂中包含一个可调的光学延迟臂，用于调节参考臂的光程，使之与样品臂的光程匹配。
SD-OCT和SS-OCT最主要的区别在于：SD-OCT采用低相干光源(Low Coherence Source,图1中简写为LCS)，并采用光谱仪(一般由衍射光栅和一维线扫描相机组成)采集干涉光谱信号；而SS-OCT采用扫频光源，并采用高速光电探测器采集干涉光谱信号。二者均采用数字信号处理单元(DSP)处理光谱信号和重建OCT结构图像。
作为示意说明，图1和图2中采用的干涉系统是迈克尔逊干涉仪。图3采用了马赫-曾德干涉仪系统。图3中，Coupler 1是第一耦合器，Coupler 2是第二耦合器，Sample Arm表示样品臂，Reference Arm表示参考臂，A’方向为样品臂的返回光，B’方向为参考臂的返回光，样品臂的返回光和参考臂的返回光在第二耦 合器Coupler 2处干涉，并被平衡探测器Balanced Detector检测。为了简化示意图，图3省略了样品臂中对被测样品的扫描装置。作为示例，图3中被测样品是眼睛，但这里的描述不仅限于眼科医学的应用。
SD-OCT和SS-OCT的成像深度受到不同系统参数的限制。SD-OCT的成像深度由光谱仪分辨率决定，在空气介质中大约为几毫米；SS-OCT成像深度由扫频光源的相干长度、光谱信号探测器带宽以及采样频率决定，成像深度通常为几毫米，最深可达上百毫米。
近十年来，SD-OCT的技术越来越成熟。目前，SD-OCT采用的低相干光源大多为超辐射发光二极管(SLD)。SLD具有稳定性高、价格低廉的特点。SS-OCT具有成像速度更快，更深和灵敏度更高等优点，很有可能会取代SD-OCT。
按输出模式来分，扫频源有单纵模输出激光与多纵模输出激光两种。从理论上讲，光频连续可调的单纵模激光对SS-OCT更为理想。但是当前市场上技术成熟并已商业化的扫频源以多纵模为主。对于多纵模激光而言，虽然输出的光谱包络看起来是连续的，但实际上光谱包络中会由于多种纵模的存在而出现梳状光谱线。相邻两个纵模的差频由扫频光源内的激光腔长决定。
对于扫频源，多种纵模同时输出会造成“相干重现”(coherence revival)效应。在SS-OCT系统中，在样品臂和参考臂光程匹配时，会观察到较强的光学干涉信号；当样品臂和参考臂的光程差正好是扫频激光器腔长的整数倍时，也会观察到较强的光学干涉信号。
相干重现效应本身并不一定有害。研究人员可以利用相干重现效应来提高OCT的成像深度，这种技术被称为“相干重现复用”(coherence revival multiplexing)。
可是相干重现效应有一个较为严重的副作用。不同于SD-OCT，在SS-OCT系统中，相干重现效应会在OCT图像中形成伪像。在SD-OCT系统中，只有当样品臂和参考臂的光程差小于系统成像深度时，才能获得较强的光学干涉信号；对于光程差大于成像深度的光信号，并不会被观测到。但对于SS-OCT系统，对于光程差大于成像深度的光信号，会由于相干重现效应而形成较强的干涉。所以，SS-OCT中更容易出现由于光路中元件反射或者散射引起的伪像。这是限制SS-OCT进一步发展的技术难题之一。
针对SS-OCT中的相干重现伪像，已经有了一些规避方法。其中一个方法是 通过光学和系统设计，使容易产生反射或散射的光学元件避开会产生相干重现伪像的位置。比如，假设扫频光源的激光腔长为50mm，那么需要通过合理的光学和系统设计，使容易产生反射或散射的光学元件到探测器的光程和SS-OCT系统中的参考臂光程差避开激光腔长的整数倍，也就是0,±50mm,±100mm,±150mm,±200mm等。但当所采用的扫频激光器腔长较短时，这种方法会有局限性。所以这种方法一般只能在扫频激光器腔长远大于所需成像深度时使用。基于这个考虑，SS-OCT系统中的扫频激光器腔长通常大于35mm。
此外，一般用于光纤系统的抑制反向信号的方法是采用环形光隔离器(Optical Isolator)。但环形光隔离器难以实现足够的光谱宽度，价格昂贵，而且容易引起额外的光损耗和偏振色散(PMD,polarization mode dispersion)，从而降低系统灵敏度。
避免相干重现伪像的方法还包括采用频域锁模(FDML)激光光源和单纵模激光光源(比如垂直腔面发射激光器VCSEL)。FDML激光光源拥有很长的激光腔长，可以有效的避免相干重现伪像。但这两种激光光源技术目前还未成熟，还无法用于商用SS-OCT系统。
在实际的光学系统设计中，由于受到某些具体的限制，上述的规避方法不一定能适用。例如，对于参考臂中光学延迟臂的杂散光引起的相干重现伪像(详见下文)，上述的规避方法不够有效。
图4是一个基于马赫-曾德干涉仪的SS-OCT系统。样品臂的返回光A’和参考臂的返回光B’在耦合器H处进行干涉，干涉信号由平衡探测器Balanced Detector检测。虽然SS-OCT系统中常用的干涉耦合器是基于光纤系统的，但参考臂中的延迟臂大多采用自由空间光学系统。延迟臂通常包含光纤端面(图4中的E和G)、准直器和反射棱镜(图4中的F)。这些光学元件都可能产生寄生反射。这些反射信号，哪怕是及其微弱，都会通过光纤端面E耦合回干涉仪的光纤系统，例如图中虚线代表反射信号C’，通过如图4路径E→B→H在耦合器H处和参考臂返回光B’进行干涉。由此延迟臂元件寄生反射产生的相干重现伪像容易和被测样品(图4中的D)的OCT结构图像混叠在一起，影响真实OCT结构图像的判断，如图5所示。由于延迟臂中能产生寄生反射的元件很多，而且延迟臂本身会在一定范围内调整光程，这就使得光学和系统设计很难保证所有这些元件(不仅限于图4中的E和G)的反射光程和被测样品(图4中的D)的光 程差能完全避开扫频光源(图4中的A)激光腔长的整数倍。
上面提过，绝大多数OCT系统是基于迈克尔逊或马赫-曾德干涉仪系统设计的。图1和图2的基于迈克尔逊干涉仪的SS-OCT系统，样品臂的光程和参考臂的光程必须匹配，才能获得光学干涉信号。同样，如图4所示，基于马赫-曾德干涉仪的SS-OCT系统，需要调整延迟臂的光程，使得样品臂和参考臂的光程(OPL,optical path length)相匹配。常见的系统设计方案如下：
前向光学路径光程:OPL(B→C→D)≈OPL(B→E→F)
后向光学路径光程:OPL(D→C→B→H)≈OPL(F→G→H)
基于这种系统设计，SS-OCT系统中将会产生由于延迟臂元件寄生反射产生的相干重现伪像，影响真实被测样品的结构图像。比如反射棱镜F处的寄生反射光程(图4中F→E→B→H路径)将和被测样品D的光程相当，从而产生影响真实被测样品或眼睛D结构图像的相干重现伪像，
OPL(F→E→B)≈OPL(D→C→B)
延迟臂中其他元件，比如光纤端面E和G，同样也容易产生影响真实被测样品结构图像的相干重现伪像。
发明内容
发明目的：为了解决现有技术存在的问题，抑制SS-OCT系统中由参考臂杂散光引起的相干重现伪像，本发明提供一种与常见OCT系统不同的设计。
技术方案：一种光学相干断层扫描成像(OCT)系统，包括扫频激光器、马赫-曾德式干涉仪、平衡探测器；干涉仪包括第一光纤耦合器、第二光纤耦合器、样品臂和参考臂；参考臂包括参考臂前段、参考臂后段及延迟臂(在一种实施方案中延迟臂本身还包括第三光纤耦合器)；每个光纤耦合器均包括第一端口、第二端口、第三端口和第四端口；扫频激光器的输出端连接第一光纤耦合器的第一端口，第一光纤耦合器的第二端口连接样品臂，第一光纤耦合器的第三端口连接参考臂前段，第一光纤耦合器的第四端口连接第二光纤耦合器的第一端口；参考臂前段的末端通过延迟臂与参考臂后段连接(在一种实施方案中此连接是通过第三光纤耦合器实现的)；第一光纤耦合器用于将扫频光源的输出光分为样品光和参考光，并将返回的样品光分配至第二光纤耦合器；参考臂后段末端连接第二光纤耦合器的第二端口；第二光纤耦合器的第三端口和第四端口连接平衡探测器；扫频激光器谐振腔长大于35mm；所述延迟臂的寄生反射信号到达第二光纤耦合 器的光程与样品光光程的差值大于扫频激光器腔长的8倍。
优选的，所述延迟臂包括光纤端面、准直器和反射光学元件；光纤端面包括参考臂前段的光纤端面和参考臂后段的光纤端面；所述准直器包括入射准直器和反射准直器；参考光经参考臂前段进入入射准直器后被反射光学元件反射；返回的参考光经反射准直器输出至参考臂后段到达第二光纤耦合器；所述参考臂前段的长度大于样品臂的长度，且参考臂前段与样品臂的长度的差值大于扫频光源腔长的8倍。
优选的，所述延迟臂包括光纤端面、准直器和反射光学元件；光纤端面包括参考臂前段的光纤端面和参考臂后段的光纤端面；所述准直器包括入射准直器和反射准直器；参考光经参考臂前段进入入射准直器后被反射光学元件反射，返回的参考光经反射准直器输出至参考臂后段到达第二光纤耦合器；设参考臂前段与延迟臂来回长度之和为L，L小于样品臂的长度，且样品臂与L的差值大于扫频光源腔长的8倍。
优选的，所述延迟臂中的准直器为单准直器，还包括第三光纤耦合器，共用于参考臂前段和参考臂后段；所述参考臂前段连接第三光纤耦合器的第一端口；第三光纤耦合器的第二端口连接单准直器；参考光进入单准直器后经反射光学元件反射原路返回再经第三光纤耦合器的第三端口输出；第三光纤耦合器的第三端口连接第二光纤耦合器的第二端口；所述参考臂前段的长度大于样品臂的长度，且参考臂前段与样品臂的长度的差值大于扫频光源腔长的8倍。这一实施方案简化了延迟臂，单准直器的延迟臂设计具有更好的稳定性和更方便的装配性。而且，第三光纤耦合器多出一个第四端口，可以用于其它实验用途，例如激光安功率全监测。
优选的，所述延迟臂中的准直器为单准直器，还包括第三光纤耦合器，第三光纤耦合器共用于参考臂前段和参考臂后段；所述参考臂前段连接第三光纤耦合器的第一端口；第三光纤耦合器的第二端口连接单准直器；参考光进入单准直器后经反射光学元件反射原路返回再经第三光纤耦合器的第三端口输出；第三光纤耦合器的第三端口连接第二光纤耦合器的第二端口；设参考臂前段与延长臂来回长度之和为L，L小于样品臂的长度，且样品臂与L的差值大于扫频光源腔长的8倍。
优选的，所述反射光学元件为角锥棱镜(Corner Reflector)。
有益效果：本发明提供的一种光学相干断层扫描成像系统，通过加长或缩短延迟臂元件寄生或杂散反射光的光程，提高相干重现伪像阶数，从而达到抑制相干重现伪像的效果。该光学相干断层扫描成像系统相比较现有技术而言，可以实现足够的光谱宽度，结构简单，成本较低，不会引起额外的光损耗和偏振色散，可以保证系统的灵敏度。
附图说明
图1为SD-OCT系统示意图；
图2为SS-OCT系统示意图；
图3为基于马赫-曾德干涉仪的SS-OCT系统示意图；
图4为延迟臂元件寄生反射示意图；
图5为由于延迟臂元件寄生反射引起的相干重现伪像示意图；
图6为实施例一的SS-OCT系统示意图；
图7为不同阶次的相干重现伪像示意图；
图8为不同阶次的相干重现伪像相对信号强度变化；
图9为实施例二的SS-OCT系统示意图；
图10为实施例三的SS-OCT系统示意图；
图11为实施例三的耦合器分光比和光功率传输细节图；
图12为采用本发明所述方法抑制相干重现伪像之后的OCT图像。
具体实施方式
下面结合附图和具体实施例对本发明作进一步说明。
实施例一：
光学相干断层扫描成像系统，包括扫频激光器1、平衡探测器2、马赫-曾德式干涉仪；干涉仪包括第一光纤耦合器3、第二光纤耦合器4、样品臂5和参考臂；参考臂包括参考臂前段61、参考臂后段62及延迟臂63；第一光纤耦合器3和第二光纤耦合器4均包括第一端口、第二端口、第三端口和第四端口；扫频激光器1的输出端连接第一光纤耦合器3的第一端口；第一光纤耦合器3的第二端口连接样品臂5；第一光纤耦合器3的第三端口连接参考臂前段61；第一光纤耦合器3的第四端口连接第二光纤耦合器4的第一端口；参考臂前段61的末端通 过延迟臂63与参考臂后段62连接；第一光纤耦合器3用于将扫频激光器1的输出光分为样品光和参考光，并将返回的样品光分配至第二光纤耦合器4；参考臂后段62末端连接第二光纤耦合器4的第二端口；第二光纤耦合器4的第三端口和第四端口连接平衡探测器2；扫频激光器的激光腔长大于35mm。
所述延迟臂63包括光纤端面、准直器631和反射光学元件632(本实施例中采用角锥棱镜)，光纤端面包括参考臂前段的光纤端面611和参考臂后段的光纤端面621；所述准直器631包括入射准直器和反射准直器，参考光经参考臂前段61进入入射准直器后被反射光学元件632反射，返回的参考光经反射准直器输出至参考臂后段62到达第二光纤耦合器4。
本实施例通过缩短参考臂后段62的光纤长度，加长参考臂前段61的光纤长度，保持路径B→E→F→G→H的总光程不变。这样，参考臂前段光学路径光程OPL(B→E)将远大于样品臂的光学路径光程OPL(B→C→D)，他们之间的光程差为L’。L’应大于扫频光源腔长的N倍，N为正整数。实验表明，当N大于8时，相干重现伪像对真实OCT图像结构的影响可以被忽略。一个特定扫频光源的实验结果如图7和8所示，其中图7中的阶数符号+表示样品臂光程大于参考臂光程，阶数符号-表示样品臂光程小于参考臂光程。在本实施例中，扫频激光器腔长为50mm，则参考臂前段与样品臂的长度的差值应大于400mm，若扫频激光器腔长为40mm，则参考臂前段与样品臂的长度的差值应大于320mm，即需要满足以下条件：
OPL(B→E)>OPL(B→C→D)+8×扫频激光器腔长
实施例二：
实施例二与实施例一的不同之处在于，实施例二是通过加长参考臂后段62的光纤长度，缩短参考臂前段61的光纤长度，达到相同抑制相干重现伪像的效果。系统其它部分与实施例一相同。
设参考臂前段61与延迟臂63来回长度之和为L，L小于样品臂的长度，且样品臂与L的差值大于扫频光源腔长的8倍。即需要满足以下条件：
OPL(B→E→F→G)<OPL(B→C→D)-8×扫频激光器腔长
实施例三：
实施例三中的延迟臂63与实施例一和实施例二有所不同，所述延迟臂63 中的准直器631为单准直器，还包括第三光纤耦合器7，第三光纤耦合器7共用于参考臂前段和参考臂后段；第三光纤耦合器7包括第一端口、第二端口及第三端口；所述参考臂前段61连接第三光纤耦合器7的第一端口，第三光纤耦合器7的第二端口连接单准直器，参考光进入单准直器后经反射光学元件632(本实施例中采用角锥棱镜)原路返回再经第三光纤耦合器7的第三端口输出；第三光纤耦合器7的第三端口连接第二光纤耦合器4的第二端口。其他部分与实施例一和实施例二相同。
如图10所示，样品臂的光程和参考臂的光程相匹配，符合以下条件
OPL(B→C→D→C→B→H)≈OPL(B→J→E→F→E→J→H)
延迟臂中元件的寄生反射光经过参考臂前段光纤端面611被耦合回干涉系统，通过第三光纤耦合器7、第一光纤耦合器3返回至第二光纤耦合器4和参考臂的返回光干涉。特别需要指出的是，由于第三光纤耦合器7的存在，寄生反射光的耦合效率提高，相干重现伪像强度也会更强。所述参考臂前段61的长度大于样品臂5的长度，且参考臂前段61与样品臂5的长度的差值大于扫频光源腔长的8倍，即需要满足如下条件，以达到抑制相干重现伪像的目的。
OPL(B→J→E)>OPL(B→C→D)+8×扫频激光器腔长
或者设参考臂前段61与延迟臂63来回长度之和为L，L小于样品臂5的长度，且样品臂5与L的差值大于扫频光源腔长的8倍，即：
OPL(B→J→E→F→E)<OPL(B→C→D)-8×扫频激光器腔长
如图10所示的本发明实施例三与实施例一和实施例二相比，简化了延迟臂63，因为单准直器的延迟臂设计具有更好的稳定性和更方便的装配性。而且，第三光纤耦合器7多出一个第四端口G，可以用于其它实验用途，例如激光功率安全监测。
图11标明了光路中的耦合器分光比和光功率传输细节。为说明起见，此处简化功率计算，忽略系统中耦合损耗，假定延迟臂的反射效率为50％。
除了图11中所示各个位置的光功率外，由延迟臂元件反射回干涉仪系统(图10中路径J→B→H)的功率为2.4×0.5×0.2×0.2＝0.048mW，约等于参考臂光功率(0.96mW)的5％。这些光虽然只会将背景噪声水平提高0.2dB，但是由于它比样品臂反射回的光信号强度高很多，如果光学和系统设计不符合前边所述光程差 条件(相干重现阶数N>8)，很容易产生相干重现伪像。
通过选取如下光纤长度(对应于图11)，相干重现伪像可以被很容易地移到20阶以上，远大于前边提到的高于8阶的要求(阶数越高，抑制相干重现伪像的效果越好)。此处假定扫频激光器腔长50mm，光耦合器的光程忽略不计。在OPL的计算中，光纤的群折射率(group refractive index)约为1.47。
光纤或空气 BJ JE EF BC CD BH HJ
长度(mm) 2000 1000 150 1830 400 200 200
前向样品臂光程OPL(B→C→D)＝1830×1.47+400≈3090mm
后向样品臂光程OPL(D→C→B→H)＝400+(1830+200)×1.47≈3384mm
总样品臂光程OPL(B→C→D→C→B→H)≈3090+3384＝6474mm
总参考臂光程OPL(B→J→E→F→E→J→H)＝(2000+1000×2+200)×1.47+150×2＝6474mm
杂散光最短前向光程OPL(B→J→E)≈(2000+1000)×1.47≈4410mm
OPL(B→J→E)-OPL(B→C→D)≈4410-3090＝1320mm≈26×扫频激光器腔长
除了图11中所示各个位置的光功率外，返回扫频光源的光功率为2.4×0.5×0.2×0.8＝0.192mW，大约是光源输出功率的1.3％。扫频光源必须能允许1.3％的光功率反射回光源。
以上三个实施例虽然对于参考臂前段或与延迟臂来回光程相加的长度的设计有所不同，但目的都是通过加长或者缩短延迟臂元件反射光的光程，使延迟臂的寄生或杂散反射信号到达第二光纤耦合器的光程与样品光光程的差值大于扫频激光器腔长的8倍，从而达到抑制相干重现伪像的目的。在实施上述方法之后，图5所示的相干重现伪像得到有效的抑制，OCT图像质量明显提高，见图12。

Claims (6)

  1. 一种光学相干断层扫描成像系统，其特征在于，包括扫频激光器、马赫-曾德式干涉仪、平衡探测器；干涉仪包括第一光纤耦合器、第二光纤耦合器、样品臂和参考臂；参考臂包括参考臂前段、参考臂后段及延迟臂；第一光纤耦合器和第二光纤耦合器均包括第一端口、第二端口、第三端口和第四端口；扫频激光器的输出端连接第一光纤耦合器的第一端口，第一光纤耦合器的第二端口连接样品臂，第一光纤耦合器的第三端口连接参考臂前段，第一光纤耦合器的第四端口连接第二光纤耦合器的第一端口；参考臂前段的末端通过延迟臂与参考臂后段连接；第一光纤耦合器用于将扫频光源的输出光分为样品光和参考光，并将返回的样品光分配至第二光纤耦合器；参考臂后段末端连接第二光纤耦合器的第二端口；第二光纤耦合器的第三端口和第四端口连接平衡探测器；扫频激光器谐振腔长大于35mm；所述延迟臂的寄生或杂散反射信号到达第二光纤耦合器的光程与样品光光程的差值大于扫频激光器腔长的8倍。
  2. 根据权利要求1所述的光学相干断层扫描成像系统，其特征在于，所述延迟臂包括光纤端面、准直器和反射光学元件；光纤端面包括参考臂前段的光纤端面和参考臂后段的光纤端面；所述准直器包括入射准直器和反射准直器；参考光经参考臂前段进入入射准直器后被反射光学元件反射，返回的参考光经反射准直器输出至参考臂后段到达第二光纤耦合器；所述参考臂前段的长度大于样品臂的长度，且参考臂前段与样品臂的长度的差值大于扫频光源腔长的8倍。
  3. 根据权利要求1所述的光学相干断层扫描成像系统，其特征在于，所述延迟臂包括光纤端面、准直器和反射光学元件；光纤端面包括参考臂前段的光纤端面和参考臂后段的光纤端面；所述准直器包括入射准直器和反射准直器，参考光经参考臂前段进入入射准直器后被反射光学元件反射，返回的参考光经反射准直器输出至参考臂后段到达第二光纤耦合器；设参考臂前段与延长臂来回长度之和为L，L小于样品臂的长度，且样品臂与L的差值大于扫频光源腔长的8倍。
  4. 根据权利要求1所述的光学相干断层扫描成像系统，其特征在于，所述延迟臂中的准直器为单准直器，还包括第三光纤耦合器，第三光纤耦合器共用于参考臂前段和参考臂后段；第三光纤耦合器包括第一端口、第二端口及第三端口；所述参考臂前段连接第三光纤耦合器的第一端口；第三光纤耦合器的第二端口连接单准直器；参考光进入单准直器后经反射光学元件反射原路返回再经第三光纤 耦合器的第三端口输出；第三光纤耦合器的第三端口连接第二光纤耦合器的第二端口；所述参考臂前段的长度大于样品臂的长度，且参考臂前段与样品臂的长度的差值大于扫频光源腔长的8倍。
  5. 根据权利要求1所述的光学相干断层扫描成像系统，其特征在于，所述延迟臂中的准直器为单准直器，还包括第三光纤耦合器，第三光纤耦合器共用于参考臂前段和参考臂后段；第三光纤耦合器包括第一端口、第二端口及第三端口；所述参考臂前段连接第三光纤耦合器的第一端口；第三光纤耦合器的第二端口连接单准直器；参考光进入单准直器后经反射光学元件反射原路返回再经第三光纤耦合器的第三端口输出；第三光纤耦合器的第三端口连接第二光纤耦合器的第二端口；设参考臂前段与延长臂来回长度之和为L，L小于样品臂的长度，且样品臂与L的差值大于扫频光源腔长的8倍。
  6. 根据权利要求2至5任一所述的光学相干断层扫描成像系统，其特征在于，所述反射光学元件为角锥棱镜。
PCT/CN2018/103869 2017-09-29 2018-09-04 一种光学相干断层扫描成像系统 WO2019062484A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US16/831,842 US11022424B2 (en) 2017-09-29 2020-03-27 Optical coherence tomography system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN201710904860.1 2017-09-29
CN201710904860.1A CN107495921B (zh) 2017-09-29 2017-09-29 一种光学相干断层扫描成像系统

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US16/831,842 Continuation US11022424B2 (en) 2017-09-29 2020-03-27 Optical coherence tomography system

Publications (1)

Publication Number Publication Date
WO2019062484A1 true WO2019062484A1 (zh) 2019-04-04

Family

ID=60699792

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2018/103869 WO2019062484A1 (zh) 2017-09-29 2018-09-04 一种光学相干断层扫描成像系统

Country Status (3)

Country Link
US (1) US11022424B2 (zh)
CN (1) CN107495921B (zh)
WO (1) WO2019062484A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3637041A4 (en) * 2017-06-07 2021-03-10 Tatsuta Electric Wire & Cable Co., Ltd. LIGHT INTERFERENCE UNIT AND LIGHT INTERFERENCE MEASUREMENT DEVICE

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107495921B (zh) * 2017-09-29 2019-02-19 视微影像(河南)科技有限公司 一种光学相干断层扫描成像系统
CN108523852A (zh) * 2018-05-10 2018-09-14 视微影像(河南)科技有限公司 一种扫频oct的光学干涉成像系统
CN108426834A (zh) * 2018-05-11 2018-08-21 佛山科学技术学院 一种快速光程扫描装置
EP3572765A1 (de) * 2018-05-23 2019-11-27 Haag-Streit Ag Oct-system und oct-verfahren
CN109602396A (zh) * 2018-12-29 2019-04-12 执鼎医疗科技（杭州）有限公司 一种击穿式全光纤参考臂扫频oct系统
CN111198169A (zh) * 2019-11-08 2020-05-26 桂林电子科技大学 微结构光纤高分辨率三维折射率测试方法
CN110836852B (zh) * 2019-11-13 2024-03-26 深圳市斯尔顿科技有限公司 工业oct检测装置及方法
CN112763422A (zh) * 2021-02-02 2021-05-07 深圳英美达医疗技术有限公司 一种偏振敏感探测分光系统及其分光探测方法
US20220296094A1 (en) * 2021-03-18 2022-09-22 Optos Plc Multimode eye analyzing system, method and computer-readable medium
CN114259203B (zh) * 2021-12-08 2022-12-30 深圳大学 芯片集成相干断层成像系统
US11933610B2 (en) * 2022-07-28 2024-03-19 Nec Corporation Optical tomography system and method of using

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101411608A (zh) * 2007-10-04 2009-04-22 佳能株式会社 光学相干断层摄像装置
CN103565405A (zh) * 2013-11-15 2014-02-12 浙江大学 基于分段光谱光程编码的谱域oct探测系统及方法
CN105748041A (zh) * 2016-02-15 2016-07-13 苏州大学 光学相干断层扫描成像中散斑噪声的抑制系统和方法
US20160206195A1 (en) * 2015-01-16 2016-07-21 Oregon Health & Science University Post-processing reduction of fixed pattern artifacts and trigger jitter in swept-source optical coherence tomography
CN106949966A (zh) * 2017-03-24 2017-07-14 中国科学院上海光学精密机械研究所 扫频光学相干层析成像系统的光谱标定方法
CN107495921A (zh) * 2017-09-29 2017-12-22 视微影像(河南)科技有限公司 一种光学相干断层扫描成像系统

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5491524A (en) * 1994-10-05 1996-02-13 Carl Zeiss, Inc. Optical coherence tomography corneal mapping apparatus
DE10041041A1 (de) * 2000-08-22 2002-03-07 Zeiss Carl Interferometeranordnung und Interferometrisches Verfahren
US7079256B2 (en) * 2003-08-09 2006-07-18 Chian Chiu Li Interferometric optical apparatus and method for measurements
WO2008090599A1 (ja) * 2007-01-22 2008-07-31 School Juridical Person Kitasato Institute オプティカル・コヒーレンス・トモグラフィー装置
WO2012100213A2 (en) * 2011-01-21 2012-07-26 Duke University Systems and methods for complex conjugate artifact resolved optical coherence tomography
US8947672B2 (en) * 2012-07-26 2015-02-03 Carl Zeiss Meditec, Inc. Systems and methods for artifact suppression by frequency shifting or cavity length adjustment
JP2017142192A (ja) * 2016-02-12 2017-08-17 株式会社トーメーコーポレーション 光干渉断層計

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101411608A (zh) * 2007-10-04 2009-04-22 佳能株式会社 光学相干断层摄像装置
CN103565405A (zh) * 2013-11-15 2014-02-12 浙江大学 基于分段光谱光程编码的谱域oct探测系统及方法
US20160206195A1 (en) * 2015-01-16 2016-07-21 Oregon Health & Science University Post-processing reduction of fixed pattern artifacts and trigger jitter in swept-source optical coherence tomography
CN105748041A (zh) * 2016-02-15 2016-07-13 苏州大学 光学相干断层扫描成像中散斑噪声的抑制系统和方法
CN106949966A (zh) * 2017-03-24 2017-07-14 中国科学院上海光学精密机械研究所 扫频光学相干层析成像系统的光谱标定方法
CN107495921A (zh) * 2017-09-29 2017-12-22 视微影像(河南)科技有限公司 一种光学相干断层扫描成像系统

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3637041A4 (en) * 2017-06-07 2021-03-10 Tatsuta Electric Wire & Cable Co., Ltd. LIGHT INTERFERENCE UNIT AND LIGHT INTERFERENCE MEASUREMENT DEVICE
US11054240B2 (en) 2017-06-07 2021-07-06 Tatsuta Electric Wire & Cable Co., Ltd. Light interference unit and light interference measurement device

Also Published As

Publication number Publication date
CN107495921A (zh) 2017-12-22
CN107495921B (zh) 2019-02-19
US20200225021A1 (en) 2020-07-16
US11022424B2 (en) 2021-06-01

Similar Documents

Publication Publication Date Title
WO2019062484A1 (zh) 一种光学相干断层扫描成像系统
Klein et al. Megahertz OCT for ultrawide-field retinal imaging with a 1050nm Fourier domain mode-locked laser
US8913248B2 (en) Systems and methods for improved balanced detection in optical coherence tomography imaging
Wang et al. Depth-encoded all-fiber swept source polarization sensitive OCT
Cense et al. Ultrahigh-resolution high-speed retinal imaging using spectral-domain optical coherence tomography
US9279659B2 (en) Systems and methods for complex conjugate artifact resolved optical coherence tomography
Götzinger et al. Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography
US20130100456A1 (en) Systems and methods for swept-source optical coherence tomography
US9492077B2 (en) Optimized device for swept source optical coherence domain reflectometry and tomography
CA3014324A1 (en) Apparatus and methods for high-speed and long depth range imaging using optical coherence tomography
US9267783B1 (en) Split integration mode acquisition for optimized OCT imaging at multiple speeds
Xu et al. Performance of megahertz amplified optical time-stretch optical coherence tomography (AOT-OCT)
Dhalla et al. Efficient sweep buffering in swept source optical coherence tomography using a fast optical switch
Klein et al. Multi-MHz FDML OCT: snapshot retinal imaging at 6.7 million axial-scans per second
US9155462B2 (en) Short coherence interferometry for measuring distances
Wang et al. Multi-channel spectral-domain optical coherence tomography using single spectrometer
CN203117457U (zh) 一种光纤导出式的干涉仪激光光源系统
Lee et al. Optical coherence tomography based on a continuous-wave supercontinuum seeded by erbium-doped fiber's amplified spontaneous emission
US11058297B2 (en) 1060 nm wavelength range-based optical coherence tomography (OCT) system for anterior/posterior segment imaging of an eye
Huang et al. Physical compensation method for dispersion of multiple materials in swept source optical coherence tomography
Zhang et al. Ultra broad band Fourier domain mode locked swept source based on dual SOAs and WDM couplers
Wang et al. A combined multiple-SLED broadband light source at 1300 nm for high resolution optical coherence tomography
Wang et al. An Optimization Method for Ultrahigh-resolution Vis-OCT Imaging
CN215651026U (zh) 一种生物测量仪
Yamada et al. Enhancement of the depth range up to 13.8 mm with filtered external k-sampling-clock in an SS-OCT system using a reflective Fabry-Perot tunable laser

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18862041

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18862041

Country of ref document: EP

Kind code of ref document: A1