WO2024040779A1 - 偏振敏感型光学相干层析成像***、方法 - Google Patents

偏振敏感型光学相干层析成像***、方法 Download PDF

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WO2024040779A1
WO2024040779A1 PCT/CN2022/135589 CN2022135589W WO2024040779A1 WO 2024040779 A1 WO2024040779 A1 WO 2024040779A1 CN 2022135589 W CN2022135589 W CN 2022135589W WO 2024040779 A1 WO2024040779 A1 WO 2024040779A1
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light
sample
polarization
sub
signal
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PCT/CN2022/135589
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English (en)
French (fr)
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李新宇
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广东大湾区空天信息研究院
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    • 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
    • G01N21/21—Polarisation-affecting properties
    • 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

Definitions

  • the present application relates to the field of optical imaging technology, and in particular to a polarization-sensitive optical coherence tomography system and method.
  • Polarization is one of the three basic properties of optical signals. Compared with intensity and frequency, most current optical imaging methods cannot directly detect the polarization characteristics of objects. Many samples in biomedical optical imaging have polarization properties, such as nerve fibers, skin, teeth, tendons, blood vessels, etc., and many diseases and external injuries can cause changes in the polarization properties of this tissue, including burns, cancer, glaucoma, and dental caries. , atherosclerosis and various neurodegenerative diseases, etc.
  • Polarization-sensitive optical coherence tomography is an imaging method that can perform tomography of biological tissues. It can obtain tissue structure information non-destructively and with high resolution, and it also has the function of obtaining the polarization characteristics of the sample.
  • Polarization-sensitive optical coherence tomography requires obtaining light field information acting on the surface of the sample, as well as light field information acting on the interior of the sample. In traditional technology, the light field information acting on the sample surface needs to be calculated through digital image processing to segment the boundaries of the sample. This method has the problems of slow processing speed and low accuracy.
  • the purpose of this application is to solve at least one of the above technical deficiencies, especially the technical deficiencies of slow processing speed and low accuracy in existing imaging systems.
  • embodiments of the present application provide a polarization-sensitive optical coherence tomography system, including a measurement light source, a sample arm, a reference arm, a polarization detection module and a control module;
  • the measurement light source is used to divide the signal light into first The signal light and the second signal light are emitted simultaneously, the first signal light is incident on the reference arm, and the second signal light is incident on the sample arm;
  • the reference arm is used to adjust the first signal light to the reference light and then emit it to the polarization detection module;
  • the sample arm includes an adjustment unit and a scanning unit.
  • the adjustment unit is used to adjust the second signal light into sample light and then shoot it to the scanning unit.
  • the scanning unit is provided with a first partial reflection unit.
  • the first partial reflection unit reflects part of the sample light to the polarization detection module to match the reference
  • the light is coherent to form the first interference light, and the first part of the reflection unit transmits the remaining sample light to the sample to be measured;
  • the sample to be measured reflects the remaining sample light to the polarization detection module to be coherent with the reference light to form the second interference light;
  • the polarization detection module uses The first interference light is processed to obtain a first electrical signal, and the second interference light is processed to obtain a second electrical signal;
  • the control module is connected to the polarization detection module, and is used to determine the polarity of the sample to be measured based on the first electrical signal.
  • the surface light field information determines the internal light field information of the sample to be measured based on the second electrical signal, and determines the polarization characteristics of the sample to be measured based on the surface light field information and the internal light field information, so as to image the sample to be measured based on the polarization characteristics.
  • the first partial reflection unit includes a first prism and a first reflector; the first prism is used to receive sample light, reflect part of the sample light to the first reflector, and transmit the remaining sample light to the object to be measured. Sample; the position of the first reflector is adjustable to change the relative optical path difference with the sample to be measured, and the first reflector is used to reflect part of the sample light toward the polarization detection module.
  • the scanning unit includes a galvanometer system and a focusing lens; the galvanometer system and the focusing lens are arranged on the optical path of the sample light between the adjustment unit and the first partial reflection unit; the galvanometer system is used to adjust the sample light direction, the sample light enters the focusing lens after adjusting the direction; the focusing lens focuses the sample light, and the sample light enters the first part of the reflection unit after being focused.
  • the sample light includes light with two orthogonal polarization directions
  • the adjustment unit includes a polarization delay unit, a first coupler, and a first collimator; the polarization delay unit is used to receive the second signal light, and convert the second signal light into the polarization delay unit.
  • the two signal lights are adjusted into two lights with orthogonal polarization directions to obtain the sample light, and the sample light is emitted to the first coupler; the sample light is sequentially coupled by the first coupler and collimated by the first collimator before emitting to the Scan unit.
  • the adjustment unit further includes a first polarization controller.
  • the second signal light passes through the first polarization controller before entering the polarization delay unit.
  • the first polarization controller is used to adjust the polarization state of the second signal light to a preset value. polarization state.
  • the reference arm includes a second polarization controller, a second collimator, a reference arm length adjustment unit, and a third collimator;
  • the second polarization controller is used to receive the first signal light and adjust the first signal
  • the polarization state of the light is the preset polarization state, the reference light is obtained, and the reference light is directed to the second collimator;
  • the reference light is collimated by the second collimator and then enters the reference arm length adjustment unit;
  • the reference arm length adjustment unit includes The distance between the second reflector and the third reflector is adjustable to adjust the length of the reference arm;
  • the reference light is reflected between the second reflector and the third reflector and then enters the third reflector.
  • the system further includes a clock generation module
  • the measurement light source includes a light emitting unit, a first light splitting unit and a second light splitting unit; the light emitting unit is used to transmit the original signal light to the first light splitting unit; the first light splitting unit It is used to divide the original signal light into clock signal light and signal light.
  • the clock signal light is incident on the clock generation module, and the signal light is incident on the second light splitting unit.
  • the clock generation module is connected with the control module and is used to generate corresponding signal light according to the clock signal light.
  • the clock signal is output to the control module; the second light splitting unit is used to divide the signal light into the first signal light and the second signal light.
  • the clock generation module includes an interferometer and a first photoelectric conversion unit; the clock signal light enters the interferometer and generates corresponding coherent light, and the first photoelectric conversion unit is used to convert the coherent light corresponding to the clock signal light into clock signal and output to the control module.
  • the polarization detection module includes a second coupler, a first polarization coupler, a second polarization coupler, a second photoelectric conversion unit and a third photoelectric conversion unit; part of the sample light reflected by the first partial reflection unit and The reference light is coherent at the second coupler to form the first interference light, and the remaining sample light reflected by the sample to be measured is coherent with the reference light at the second coupler to form the second interference light; the second coupler is used to split the first interference light , to obtain the first sub-interference light and the second sub-interference light, and to split the second interference light to obtain the third sub-interference light and the fourth sub-interference light; the first sub-interference light and the third sub-interference light
  • the first polarization coupler is incident, and the second sub-interference light and the fourth sub-interference light are incident on the second polarization coupler; the first polarization coupler is used to polarize and split the first sub-interference light and the third sub-interference light, respectively,
  • the vertical component and the horizontal component of the second sub-interference light, the vertical component and the horizontal component of the fourth sub-interference light; the vertical component of the second sub-interference light and the vertical component of the fourth sub-interference light respectively enter the second photoelectric conversion unit, and the second The horizontal component of the sub-interference light and the horizontal component of the fourth sub-interference light are respectively incident on the third photoelectric conversion unit; the second photoelectric conversion unit is used for photoelectric conversion of the vertical component of the first sub-interference light and the vertical component of the second sub-interference light.
  • the third photoelectric conversion unit For photoelectric conversion of the horizontal component of the first sub-interference light and the horizontal component of the second sub-interference light to obtain the horizontal component of the first electrical signal, and for converting the horizontal component of the third sub-interference light and the fourth sub-interference light
  • the horizontal component of the light is photoelectrically converted to obtain the horizontal component of the second electrical signal.
  • embodiments of the present application provide a polarization-sensitive optical coherence tomography method, which includes: a measurement light source emits a first signal light and a second signal light; the first signal light is incident on the reference arm, and the second signal light is incident on the reference arm.
  • Sample arm after the first signal light enters the reference arm, it is adjusted to the reference light, and the reference light is directed to the polarization detection module; after the second signal light enters the sample arm, it is adjusted to the sample light, and part of the sample light is reflected by the first part of the reflection unit toward the polarization
  • the detection module coheres with the reference light to form the first interference light, and the remaining sample light passes through the first part of the reflection unit and is emitted to the sample to be measured; the sample to be measured reflects the remaining sample light to the polarization detection module to form the second interference light in coherence with the reference light.
  • the first interference light is processed by the polarization detection module to generate a first electrical signal
  • the second interference light is processed by the polarization detection module to generate a second electrical signal
  • the control module determines the surface light field information of the sample to be measured based on the first electrical signal , determine the internal light field information of the sample to be measured based on the second electrical signal, and determine the polarization characteristics of the sample to be measured based on the surface light field information and internal light field information, so as to image the sample to be measured based on the polarization characteristics.
  • the first partial reflection unit inside the sample arm, part of the sample light is reflected back to the system before entering the sample to be measured, so as to obtain the light before the sample light enters the sample.
  • field information so that the polarization characteristics of the sample to be measured can be determined more accurately and quickly, and finally a more accurate image can be formed.
  • This system is based on hardware to obtain the light field information before the sample light enters the sample, reducing the complexity of data processing, eliminating the problem of inaccurate calculation of polarization characteristics caused by inaccurate positioning of the sample surface, and contributing to the improvement of the PSOCT imaging system. Instrumentation and clinical application promotion.
  • the current measurement light source has the problem of phase instability, which will affect the accuracy of data processing.
  • the surface light field information can be used to calibrate the light source phase. Obtaining a stable phase will help to obtain high-quality images.
  • Figure 1 is a schematic structural diagram of a polarization-sensitive optical coherence tomography system provided by an embodiment of the present application
  • Figure 2 is a schematic structural diagram of a scanning unit in an embodiment of the present application.
  • Figure 3 is a schematic structural diagram of a scanning unit in another embodiment of the present application.
  • Figure 4 is a schematic structural diagram of an adjustment unit in an embodiment of the present application.
  • Figure 5 is a schematic structural diagram of the reference arm in one embodiment of the present application.
  • Figure 6 is a schematic structural diagram of a polarization detection module in one embodiment of the present application.
  • Figure 7 is a schematic structural diagram of a polarization-sensitive optical coherence tomography system provided by another embodiment of the present application.
  • Figure 8 is a schematic structural diagram of a polarization-sensitive optical coherence tomography system provided by yet another embodiment of the present application.
  • embodiments of the present application provide a polarization-sensitive optical coherence tomography system, which may also be referred to as a PSOCT (Polarization-Sensitive Optical Coherence Tomography) imaging system.
  • the PSOCT imaging system can be subdivided into two types: single-incidence state PSOCT and multi-incidence state PSOCT.
  • the former determines the polarization characteristics of the tissue by accurately controlling the polarization state of the light irradiated onto the sample and detecting the change in the polarization state of the reflected light.
  • Multi-incidence PSOCT uses two beams of polarized light with orthogonal polarization states to illuminate the sample, and obtains the polarization states of the two reflected lights respectively, eliminating the influence of optical fibers on the polarization state, and finally obtaining the polarization characteristics of the sample.
  • This method does not require strict control of the polarization state of the incident light, so it can adopt a fiber structure design scheme that requires minimal alignment, is easier to operate and maintain, has good stability, and is more suitable for clinical applications.
  • the PSOCT imaging system in this application is also mainly aimed at multi-incidence state PSOCT.
  • the light incident on the object to be measured will be reflected on the surface of the sample to be measured, and on the other hand, it will be reflected deep inside the sample to be measured.
  • analysis methods such as Jones matrix
  • both parts of the light field information need to be determined. Therefore, it is necessary to extract the position coordinates of the sample surface, and then obtain the polarization information of the sample at different depths through matrix calculation.
  • the current mainstream method is to segment tissue boundaries through digital image processing calculations. This software method will first slow down the data processing speed. Secondly, it is often difficult to distinguish the interface positions between different tissues for non-smooth tissue boundaries, resulting in inaccurate calculation results. The obtained polarization characteristics are distorted.
  • the thicker lines with arrows in Figure 1 represent light.
  • the dotted lines represent the light that is reflected at the corresponding position and is finally transmitted to the polarization detection module 140, while the thinner lines with no arrows represent the light.
  • Those with arrows represent electrical connections.
  • the arrows in Figure 1 only represent the relationship between light rays between devices, not the actual propagation direction of light rays in space. Light rays can propagate between different devices based on optical fibers, rather than propagating in free space.
  • the imaging system in this embodiment includes a measurement light source 110, a sample arm 120, a reference arm 130, a polarization detection module 140 and a control module 150.
  • the measurement light source 110 is used to divide the signal light into a first signal light and a second signal light and emit the signal light.
  • the first signal light is incident on the reference arm 130 and the second signal light is incident on the sample arm 120 . That is, inside the measurement light source 110, the signal light can be split according to the first ratio to obtain the first signal light entering the sample arm 120 and the second signal light entering the reference arm 130 respectively.
  • the first ratio may be 10% of the first signal light and 90% of the second signal light.
  • the reference arm 130 is used to adjust the first signal light into reference light and then transmit it to the polarization detection module 140 .
  • the reference light will merge with the light corresponding to the sample arm 120 at the polarization detection module 140 and interfere.
  • a pair of mirrors is generally provided inside the reference arm 130. By changing the distance between the mirrors, the length of the reference arm 130 can be changed, thereby adjusting the optical path difference between the reference arm 130 and the sample arm 120 to adjust the interference effect.
  • the sample arm 120 includes an adjustment unit 121 and a scanning unit 122.
  • the adjustment unit 121 is used to adjust the second signal light into sample light and then transmit it to the scanning unit 122.
  • the adjustment made by the adjustment unit 121 generally includes adjusting the polarization state of the second signal light, adjusting the second signal light into an optical signal with orthogonal polarization directions, and passing the two optical signals through Time multiplexing, frequency multiplexing or depth multiplexing are distinguished.
  • the light can be emitted from the scanning unit 122 to the sample 10 to be measured.
  • a reflective surface is added in front of sample 10. The light field matrix returned by this additional reflective surface can replace the light field matrix on the sample surface, and the polarization characteristics of the sample can be calculated based on this.
  • this reflective surface can also calibrate the phase of the interference light signal and improve the imaging quality.
  • the scanning unit 122 is provided with a first partial reflection unit 122A.
  • the first partial reflection unit 122A is a lens structure with a certain reflectivity, that is, part of the sample light will be reflected by the first partial reflection unit 122A, and the remaining sample light that is not reflected will be directed to the sample 10 to be measured through the first partial reflection unit 122A. For example, if 1% of the sample light is reflected, the remaining 99% of the light will be transmitted to the sample 10 under test.
  • the first partial reflection unit 122A reflects part of the sample light, the reflected part of the sample light should be transmitted to the polarization detection module 140, where it merges and interferes with the reference light in the polarization detection module 140 to form the first interference light.
  • the remaining sample light in the sample light that is not reflected by the first partial reflection unit 122A will be injected into the sample to be measured 10 and reflected inside the sample to be measured 10.
  • the reflected remaining sample light should be transmitted to the polarization detection module 140. It merges with the reference light in the polarization detection module 140 and interferes to form a second interference light.
  • Figure 1 does not show the relationship between the above two reflected lights and the polarization detection module 140.
  • the reflection to the polarization detection module 140 mentioned in this application is not the light path directly pointing to the polarization detection module 140, but can be through other optical paths.
  • the transmission of components finally reaches the polarization detection module 140.
  • a light collection subunit can be set up in front of the first partial reflection unit 122A to collect the two reflected lights respectively, and then transmit them to the polarization detection module 140 through optical fibers or free space.
  • the polarization detection module 140 is used to process the first interference light to obtain a first electrical signal, and to process the second interference light to obtain a second electrical signal. In order to facilitate data processing, the polarization detection module 140 can at least perform photoelectric conversion processing. If the Jones matrix analysis method is adopted, the first interference light or the second interference light can also be converted into vertical components and horizontal components before photoelectric conversion. Decomposition and other processing.
  • the control module 150 is connected to the polarization detection module 140 and is used to determine the surface light field information of the sample to be tested 10 based on the first electrical signal, determine the internal light field information of the sample to be measured 10 based on the second electrical signal, and determine the surface light field information and internal light field information of the sample to be measured based on the second electrical signal. The light field information determines the polarization characteristics of the sample to be measured 10, so that the sample to be measured 10 is imaged according to the polarization characteristics.
  • polarized light can be represented by a Jones matrix.
  • the sample 10 to be tested itself can also be regarded as an optical element that can be represented by a Jones matrix, and the difference between the first interference light and the second interference light is that the second interference light passes through the sample 10 to be tested and the first interference light There is no light.
  • the relevant information of the Jones matrix of the sample to be tested 10 can be determined, and the polarization characteristics of the sample to be tested 10 can be determined based on the relevant information.
  • the image formed based on the accurate polarization characteristics of the sample to be tested 10 will be more conducive to judging the state of the sample to be tested 10 .
  • the position, reflectivity and shape of the first partial reflective unit 122A can be freely adjusted to parameters suitable for imaging according to needs.
  • measuring the phase stability of the light source 110 will affect the accuracy of data processing.
  • the surface light field information can be used to calibrate the light source phase. Obtaining a stable phase helps to obtain high-quality images.
  • a first partial reflection unit 122A is provided inside the sample arm 120, so that part of the sample light enters The sample 10 to be tested is previously reflected back to the system to obtain the light field information before the sample light enters the sample, so that the polarization characteristics of the sample 10 to be tested can be determined more accurately and quickly, and finally a more accurate image is formed.
  • This embodiment obtains the light field information before the sample light enters the sample based on hardware, reduces the complexity of data processing, eliminates the problem of inaccurate calculation of polarization characteristics caused by inaccurate positioning of the sample surface, and is helpful for the PSOCT imaging system.
  • the current measurement light source has the problem of phase instability, which will affect the accuracy of data processing.
  • the surface light field information can be used to calibrate the light source phase. Obtaining a stable phase will help to obtain high-quality images.
  • the scanning unit 122 includes a galvanometer system 122C and a focusing lens 122B.
  • the galvanometer system 122C and the focusing lens 122B are arranged on the optical path of the sample light between the adjustment unit 121 and the first partial reflection unit 122A.
  • the galvanometer system 122C is used to adjust the direction of the sample light, and the sample light enters the focusing lens 122B after the direction is adjusted.
  • the focusing lens 122B focuses the sample light, and the sample light enters the first partial reflection unit 122A after being focused. It can be understood that during imaging, multiple positions of the sample to be tested 10 need to be scanned.
  • the position where the sample light hits the sample to be tested 10 can be changed, thereby realizing scanning of different positions of the sample to be tested 10 .
  • part of the sample light reflected at the first partial reflection unit 122A and the remaining sample light reflected at the sample to be measured 10 return along the original path of the thick black line in the figure, which can be set on the oscillator.
  • the light collection subunit in front of the mirror system 122C collects these two reflected lights and then transmits them to the polarization detection module 140 to reflect part of the sample light to the polarization detection module 140 and reflect the remaining sample light to the polarization detection module 140 respectively.
  • the first partial reflection unit 122A may be composed of at least a first prism 122A1 and a first reflector 122A2.
  • the first prism 122A1 is used to receive the sample light, reflect part of the sample light to the first reflecting mirror 122A2, and transmit the remaining sample light to the sample 10 to be measured.
  • the position of the first reflecting mirror 122A2 is adjustable to change the relative optical path difference with the sample 10 to be measured.
  • the first reflecting mirror 122A2 is used to reflect part of the sample light toward the polarization detection module 140 .
  • This design can control the relative optical path difference between the reflective surface and the sample by adjusting the first reflector 122A2 away from or close to the first prism 122A1.
  • the first prism 122A1 reflects part of the sample light to the first reflector 122A2
  • the first reflector 122A2 reflects the part of the sample light back along the original path of the thicker black line in Figure 3
  • the remaining sample light reflected at the sample 10 to be tested returns along the thick black line in the figure.
  • the two reflected lights can be collected by the light collection sub-unit provided in front of the galvanometer system 122C, and then transmitted to the polarized light.
  • the detection module 140 is configured to respectively reflect part of the sample light to the polarization detection module 140 and reflect the remaining sample light to the polarization detection module 140 .
  • the sample arm 120, the reference arm 130 and the irradiation point of the sample to be measured 10 can be set to a free space type. That is, the measurement light source 110 can transmit the first signal light to the reference arm 130 through the optical fiber, and also transmit the second signal light to the sample arm 120 through the optical fiber.
  • the sample arm 120 and the reference arm 130 also transmit light to the polarization detection module 140 through optical fibers respectively.
  • the reference arm 130 will be described below.
  • the sample should be illuminated by two light signals with orthogonal polarization states, that is, the sample light includes two lights with orthogonal polarization directions.
  • the adjustment unit 121 includes a first polarization controller 121D, Polarization delay unit 121A, first coupler 121B and first collimator 121C.
  • the second signal light passes through the first polarization controller 121D before entering the polarization delay unit 121A.
  • the first polarization controller 121D is used to adjust the polarization state of the second signal light to a preset polarization state.
  • the adjustment of the first polarization controller 121D is used in front of the polarization delay unit 121A to make the intensity of the generated optical signals with orthogonal polarization directions similar to each other to ensure imaging quality.
  • the polarization delay unit 121A is used to receive the second signal light, adjust the second signal light into light with two orthogonal polarization directions to obtain sample light, and emit the sample light to the first coupler 121B.
  • the polarization delay unit is a device commonly used in the optical field that divides a light into two linearly polarized lights with vertical polarization directions.
  • the coupler can be used to ensure the interconnection of multiple sets of optical signals.
  • the collimator is an input and output element used to increase the output or reception efficiency of light, which can ensure that the light transmitted between the scanning unit 122 and the adjustment unit 121 has greater efficiency. Therefore, the sample light can be coupled to the scanning unit 122 efficiently and accurately after being coupled by the first coupler 121B and collimated by the first collimator 121C.
  • the sample light passes through the scanning unit 122, and part of the sample light is reflected by the first partial reflection unit 122A, and is transmitted after passing through the device before the first partial reflection unit 122A in the scanning unit 122, the first collimator 121C, and the first coupler 121B.
  • a coupler may also be provided at the polarization detection module 140 to receive light.
  • the reflected part of the sample light and the reference light are coherent at the coupler to generate first interference light.
  • the remaining sample light passes through the first partial reflection unit 122A and enters the sample 10 to be measured.
  • the remaining sample light reflected by the sample 10 to be measured passes through the scanning unit 122, the first collimator 121C, and the first coupler 121B in sequence, and then is transmitted to the polarization detection Module 140, the reflected remaining sample light and the reference light are coherent at the coupler at the polarization detection module 140, generating second interference light.
  • the reference arm 130 includes a second polarization controller 131 , a second collimator 132 , a reference arm length adjustment unit 133 , and a third collimator 134 .
  • the second polarization controller 131 is used to receive the first signal light, adjust the polarization state of the first signal light to a preset polarization state, obtain reference light, and emit the reference light to the second collimator 132 .
  • the reference light is collimated by the second collimator 132 and then enters the reference arm length adjustment unit 133.
  • the reference arm length adjustment unit 133 includes a second reflector and a third reflector, and the distance between the second reflector and the third reflector is adjustable to adjust the reference arm length.
  • the reference light is reflected between the second reflector and the third reflector and then enters the third collimator 134 . It is collimated by the third collimator 134 and then enters the polarization detection module 140 .
  • the optical signal first adjusts the polarization state by the polarization controller, and then is collimated by the second collimator 132, and then reflected by a pair of mirrors. After reflection, the optical signal is then collimated by the third collimator. The optical fiber is collected back by the detector 134 and then reaches the polarization detection module 140.
  • the length of the reference arm 130 can be controlled by adjusting the distance between the second reflector and the third reflector.
  • the polarization detection module 140 includes a second coupler 141 , a first polarization coupler 142 , a second polarization coupler 143 , a second photoelectric conversion unit 144 and a third photoelectric conversion unit 145 .
  • Part of the sample light and the reference light reflected by the first partial reflection unit 122A are coherent at the second coupler 141 to form the first interference light, and the remaining sample light reflected by the sample 10 to be measured is coherent with the reference light at the second coupler 141 to form the second interference light.
  • the second coupler 141 splits them in a ratio of 50:50.
  • an interference light includes two orthogonal polarization states. By dividing each polarization state into a horizontal component and a vertical component, a 2x2 matrix can be used to represent the interference light, as shown in the following formula:
  • E represents the light field information of an interference light, which includes two orthogonal polarization states E 1 and E 2 .
  • E H1 is the vertical component of the polarization state E 1
  • E V1 is the horizontal component of the polarization state E 1 .
  • E H2 is the vertical component of the polarization state E 2
  • E V2 is the horizontal component of the polarization state E 2 .
  • the processing process of the first interference light will be described first.
  • the first interference light is divided into a first sub-interference light and a second sub-interference light.
  • Polarizing couplers can divide light into two components: vertical and vertical.
  • the first sub-interference light enters the first polarization coupler 142, and the vertical component and the horizontal component of the first sub-interference light are obtained.
  • the second sub-interference light enters the second polarization coupler 143, and the vertical component and the horizontal component of the second sub-interference light are obtained.
  • the second photoelectric conversion unit 144 corresponds to the vertical component.
  • the vertical components of the first sub-interference light and the second interference light are both incident on the second photoelectric conversion unit 144.
  • the second photoelectric conversion unit 144 converts the vertical component of the first sub-interference light and the second interference light.
  • the vertical component of the two-sub interference light undergoes photoelectric conversion to obtain the vertical component of the first electrical signal, which is equivalent to obtaining E H1 and E H2 corresponding to the first interference light.
  • the third photoelectric conversion unit 145 corresponds to the horizontal component.
  • the horizontal components of the first sub-interference light and the second interference light are both incident on the third photoelectric conversion unit 145.
  • the third photoelectric conversion unit 145 converts the horizontal component of the first sub-interference light and the second interference light.
  • the horizontal component of the two-sub interference light undergoes photoelectric conversion to obtain the horizontal component of the first electrical signal, which is equivalent to obtaining E V1 and E V2 corresponding to the first interference light.
  • the control module 150 can determine the light field information of the first interference light based on the vertical component and the horizontal component of the first electrical signal, and the first interference light is generated based on the partial sample light reflected by the first partial reflection unit 122A. Control The module 150 is equivalent to determining the surface light field information of the sample 10 to be tested.
  • the electrical signal can be divided into components in two directions, but that the first interference light includes vertical components and vertical components of two polarization states respectively.
  • the first electrical signal is composed of two electrical components. It consists of signals, one of which corresponds to the vertical components of the two polarization states of the first interference light, is called the vertical component of the first electrical signal, and the other corresponds to the horizontal components of the two polarization states of the first interference light, then is called the horizontal component of the first electrical signal.
  • the second electrical signal which will not be described again later.
  • the processing process of the second interference light is similar, and the second interference light is divided into the third sub-interference light and the fourth sub-interference light.
  • the third sub-interference light enters the first polarization coupler 142 to obtain the vertical component and the horizontal component of the third sub-interference light.
  • the fourth sub-interference light enters the second polarization coupler 143, and the vertical component and the horizontal component of the fourth sub-interference light are obtained.
  • the second photoelectric conversion unit 144 corresponds to the vertical component.
  • the vertical components of the third sub-interference light and the fourth interference light are both incident on the second photoelectric conversion unit 144.
  • the second photoelectric conversion unit 144 responds to the vertical component of the third sub-interference light and the third sub-interference light.
  • the vertical component of the four-sub interference light undergoes photoelectric conversion to obtain the vertical component of the second electrical signal, which is equivalent to obtaining E H1 and E H2 corresponding to the second interference light.
  • the third photoelectric conversion unit 145 corresponds to the horizontal component.
  • the horizontal components of the third sub-interference light and the fourth interference light are both incident on the third photoelectric conversion unit 145.
  • the third photoelectric conversion unit 145 converts the horizontal component of the third sub-interference light and the fourth interference light.
  • the horizontal component of the four-sub interference light undergoes photoelectric conversion to obtain the horizontal component of the second electrical signal, which is equivalent to obtaining E V1 and E V2 corresponding to the second interference light.
  • the control module 150 can determine the light field information of the second interference light based on the vertical component and the horizontal component of the second electrical signal, and the second interference light is generated based on the remaining sample light reflected by the sample 10 to be tested.
  • the control module 150 150 is equivalent to determining the internal light field information of the sample 10 to be tested.
  • a third polarization controller may be disposed in front of the first polarization coupler 142, and a fourth polarization controller may be disposed in front of the second polarization coupler 143. Both polarization controllers can be used to ensure that the intensity of the generated optical signals in the two polarization states is similar to ensure imaging quality.
  • the system further includes a clock generation module 160
  • the measurement light source 110 includes a light emitting unit 111 , a first light splitting unit 112 and a second light splitting unit 113 .
  • the light emitting unit 111 is used to emit original signal light to the first light splitting unit 112 .
  • the light emitting unit 111 is the initial light source, which may be a frequency swept light source.
  • the first light splitting unit 112 is used to divide the original signal light into clock signal light and signal light, where the ratio of the signal light should be much larger than the clock signal light, such as 99:1.
  • the clock signal light is incident on the clock generation module 160 , and the signal light is incident on the second light splitting unit 113 .
  • the clock signal light has the same origin as the signal light, so it can be used to extract the clock signal related to the signal light to control the light emitting unit 111 .
  • the clock generation module 160 is connected to the control module 150 and is used to generate a clock signal corresponding to the signal light according to the clock signal light and output it to the control module 150 .
  • the second light splitting unit 113 is used to divide the signal light into first signal light and second signal light.
  • the clock generation module 160 includes an interferometer and a first photoelectric conversion unit.
  • the clock signal light enters the interferometer and generates corresponding coherent light.
  • the first photoelectric conversion unit is used to convert the coherent light corresponding to the clock signal light into a clock signal and output it to the control module 150 .
  • the technology of using an interferometer to generate a clock signal is relatively mature and will not be described in detail here.
  • the interferometer may be a Mach-Zehnder interferometer.
  • the optical path in this application will be explained again with the detailed imaging system shown in FIG. 8 .
  • the original signal light is emitted by the light emitting unit 111 and passes through the first spectroscopic unit 112 to introduce 1% of the light into the Mach-Zehnder interferometer 161 .
  • the coherent light is collected by the photodetector 162 to generate a clock signal and transmitted to the control module 150 .
  • 99% of the light emitted from the light emitting unit 111 is split by the second spectroscopic unit 113, and 10% enters the reference arm 130 as the first signal light. 90% enters the sample arm 120 as the second signal light.
  • the optical signal first adjusts the polarization state by the second polarization controller 131, and then is collimated by the second collimator 132, and is reflected by the reference arm length adjustment unit 133 including a pair of mirrors. After reflection, the light signal The signal is collected back to the optical fiber by the third collimator 134, and then reaches the second coupler 141.
  • the length of the reference arm can be controlled by adjusting the distance between the third reflector and the fourth reflector.
  • the optical signal first enters the first polarization controller 121D to adjust the polarization state, and then enters the polarization delay unit 121A.
  • the polarization delay unit 121A can be used to generate two optical signals with orthogonal polarization directions, and multiplex the two through time. , to distinguish between frequency reuse or depth reuse.
  • the two optical signals with orthogonal polarization directions then pass through the first coupler 121B and enter the scanning unit 122 through the first collimator 121C.
  • the two light signals with orthogonal polarization directions are reflected at the sample.
  • the reflected light returned from the scanning unit 122 is collected by the first collimator 121C, passes through the coupler 121B, and finally reaches the second coupler 141.
  • the second coupler 141 is coherent with the reference light, and the coherent light is coupled
  • the second coupler 141 is used to split the beam in a 50:50 ratio, and then the first polarization coupler 142 and the second polarization coupler 143 are used to divide the interference light signal into two components with orthogonal polarization directions, two
  • the vertical component port of the polarization coupler is connected to the second photoelectric conversion unit 144, and the horizontal component output port is connected to the third photoelectric conversion unit 145.
  • the first polarization coupler is ensured by adjusting the third polarization controller 146 and the fourth polarization controller 147. 142.
  • the directions of the horizontal and vertical components of the output signal of the second polarization coupler 143 are consistent respectively.
  • the two photoelectric conversion units convert the optical signals into electrical signals, which are then collected and processed by the control module 150 , and the control module 150 synchronously controls the scanning of the sample arm 130 .
  • Determining the polarization characteristics of the sample to be measured based on the surface light field information and the internal light field information can be as follows: first, define the Jones matrix at the exit of the polarization delay unit 121A to the first part of the reflection unit in the scanning unit 122 as J in , and the first part of the reflection unit The Jones matrix from the unit to the second photoelectric conversion unit 144 or the third photoelectric conversion unit 145 is J out , and the Jones matrix from the first partial reflection unit to somewhere inside the sample to be measured and then reflected back to the first partial reflection unit is J sample . Therefore, the light field of the first interference light can be expressed as:
  • E in is the light field signal of the light emitted from the polarization delay unit 121A, is the first phase factor.
  • the light fields of the first interference light and the second interference light here may be determined based on the outputs of the second photoelectric conversion unit 144 and the third photoelectric conversion unit 155 . Dividing the above two equations we get:
  • J C is a diagonal matrix and J A is a unitary matrix. Therefore:
  • J U J out J A , so J U is also a unitary matrix.
  • J C J a diagonal matrix
  • eta is the phase delay. Based on the characteristics of unitary matrix, for By calculating the eigenvalues of this matrix, P 1 e i ⁇ /2 and P 2 e -i ⁇ /2 can be obtained respectively. From this, the phase delay and dichroism of the sample to be tested can be obtained, that is, the sample to be tested can be calculated. Polarization properties.
  • embodiments of the present application provide a polarization-sensitive optical coherence tomography method, which includes: the measurement light source 110 emits a first signal light and a second signal light; the first signal light enters the reference arm 130, and the second signal The light enters the sample arm 120; the first signal light enters the reference arm 130 and is adjusted to the reference light, and the reference light is directed to the polarization detection module 140; the second signal light enters the sample arm 120 and is adjusted to the sample light, and part of the sample light is A part of the reflective unit 122A is reflected to the polarization detection module 140 to be coherent with the reference light to form the first interference light.
  • the remaining sample light passes through the first part of the reflective unit 122A and is emitted to the sample 10 to be measured; the sample 10 to be measured reflects the remaining sample light to the polarized light.
  • the detection module 140 is used to form a second interference light that is coherent with the reference light; the first interference light is processed by the polarization detection module 140 to generate a first electrical signal, and the second interference light is processed by the polarization detection module 140 to generate a second electrical signal; control
  • the module 150 determines the surface light field information of the sample to be tested 10 based on the first electrical signal, determines the internal light field information of the sample to be measured 10 based on the second electrical signal, and determines the polarization of the sample 10 to be measured based on the surface light field information and the internal light field information. characteristics to image the sample 10 to be tested according to the polarization characteristics. The description of this method can be found above.

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Abstract

一种偏振敏感型光学相干层析成像***及成像方法。测量光源（110）将信号光分为第一和第二信号光并发射；参考臂（130）将第一信号光调整为参考光后射向偏振探测模块（140）；样品臂（120）包括调整单元（121）和扫描单元（122），调整单元（121）将第二信号光调整为样品光后射向扫描单元（122），扫描单元（122）设置有第一部分反射单元（122A），第一部分反射单元（122A）将部分样品光反射向偏振探测模块（140），以与参考光相干形成第一干涉光，第一部分反射单元（122A）将剩余样品光透射向待测样品（10）；待测样品（10）将剩余样品光反射向偏振探测模块（140），以与参考光相干形成第二干涉光；控制模块（150）根据第一干涉光对应的第一电信号、第二干涉光对应的第二电信号确定待测样品（10）的偏振特性以进行成像。成像***降低了数据处理的复杂度，排除了因样品表面定位不准而导致的计算不准确。

Description

偏振敏感型光学相干层析成像***、方法
本申请要求于2022年8月22日提交中国专利局、申请号为202211002765.X、发明名称为“偏振敏感型光学相干层析成像***、方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光学成像技术领域，尤其涉及一种偏振敏感型光学相干层析成像***、方法。
背景技术
偏振是光信号的三大基本属性之一，相比强度和频率，目前大多数光学成像方法不能直接探测物体的偏振特性。在生物医学光学成像中很多样品都具有偏振特性，例如神经纤维、皮肤、牙齿、肌腱、血管等，而且很多疾病和外部损伤都会导致这种组织偏振特性的变化，包括烧伤、癌变、青光眼、龋齿、动脉粥样硬化以及各类神经退行性病变等。
偏振敏感型光学相干层析成像是一种可以对生物组织进行断层扫描的成像方法，在无损、高分辨率地得到组织结构信息的基础上还具备获得样品偏振特性的功能。偏振敏感型光学相干层析成像需要获取作用于样品表面的光场信息，也需要获取经样品内部作用后的光场信息。传统技术中对于作用于样品表面的光场信息需要通过数字图像处理计算来分割样品的边界，该方式存在着处理速度慢且精度不高的问题。
发明内容
本申请的目的旨在至少能解决上述的技术缺陷之一，特别是现有成像***中处理速度慢，且精度不高的技术缺陷。
第一方面，本申请实施例提供了一种偏振敏感型光学相干层析成像***，包括测量光源、样品臂、参考臂、偏振探测模块以及控制模块；测量光源用于将信号光分为第一信号光和第二信号光并发射，第一信号光入射参考臂，第二信号光入射样品臂；参考臂用于将第一信号光调整为参考光后射向偏振探测模块；样品臂包括调整单元和扫描单元，调整单元用于将第二信号光调整为样品光后射向扫描单元，扫描单元设置有第一部分反射 单元，第一部分反射单元将部分样品光反射向偏振探测模块，以与参考光相干形成第一干涉光，第一部分反射单元将剩余样品光透射向待测样品；待测样品将剩余样品光反射向偏振探测模块，以与参考光相干形成第二干涉光；偏振探测模块用于对第一干涉光进行处理得到第一电信号，以及用于对第二干涉光进行处理得到第二电信号；控制模块与偏振探测模块连接，用于根据第一电信号确定待测样品的表面光场信息，根据第二电信号确定待测样品的内部光场信息，并根据表面光场信息、内部光场信息确定待测样品的偏振特性，以根据偏振特性对待测样品进行成像。
在其中一个实施例中，第一部分反射单元包括第一棱镜和第一反射镜；第一棱镜用于接收样品光，将部分样品光反射向第一反射镜，并将剩余样品光透射向待测样品；第一反射镜的位置可调，以改变与待测样品的相对光程差，第一反射镜用于将部分样品光反射向偏振探测模块。
在其中一个实施例中，扫描单元包括振镜***和聚焦透镜；振镜***和聚焦透镜设置在调整单元、第一部分反射单元之间的样品光的光路上；振镜***用于调整样品光的方向，样品光经过方向调整后入射聚焦透镜；聚焦透镜对样品光进行聚焦，样品光经过聚焦后入射第一部分反射单元。
在其中一个实施例中，样品光包括两个偏振方向正交的光，调整单元包括偏振延迟单元、第一耦合器以及第一准直器；偏振延迟单元用于接收第二信号光，将第二信号光调整为两个偏振方向正交的光，以得到样品光，并将样品光射向第一耦合器；样品光依次经第一耦合器耦合、第一准直器准直后射向扫描单元。
在其中一个实施例中，调整单元还包括第一偏振控制器，第二信号光入射偏振延迟单元前经过第一偏振控制器，第一偏振控制器用于调整第二信号光的偏振态为预设偏振态。
在其中一个实施例中，参考臂包括第二偏振控制器、第二准直器、参考臂长调节单元、第三准直器；第二偏振控制器用于接收第一信号光，调整第一信号光的偏振态为预设偏振态，得到参考光，并将参考光射向第二准直器；参考光经第二准直器准直后入射参考臂长调节单元；参考臂长调节单元包括第二反射镜和第三反射镜，第二反射镜和第三反射镜之间的距 离可调，以调整参考臂长；参考光在第二反射镜和第三反射镜之间反射后入射第三准直器，并经过第三准直器准直后入射偏振探测模块。
在其中一个实施例中，***还包括时钟生成模块，测量光源包括光发射单元、第一分光单元和第二分光单元；光发射单元用于向第一分光单元发射原始信号光；第一分光单元用于将原始信号光分为时钟信号光和信号光，时钟信号光入射时钟生成模块，信号光入射第二分光单元；时钟生成模块与控制模块连接，用于根据时钟信号光生成与信号光对应的时钟信号并输出至控制模块；第二分光单元用于将信号光分为第一信号光和第二信号光。
在其中一个实施例中，时钟生成模块包括干涉仪和第一光电转换单元；时钟信号光入射干涉仪并产生对应的相干光，第一光电转换单元用于将时钟信号光对应的相干光转换为时钟信号并输出至控制模块。
在其中一个实施例中，偏振探测模块包括第二耦合器、第一偏振耦合器、第二偏振耦合器、第二光电转换单元和第三光电转换单元；第一部分反射单元反射的部分样品光和参考光在第二耦合器相干形成第一干涉光，待测样品反射的剩余样品光与参考光在第二耦合器相干形成第二干涉光；第二耦合器用于对第一干涉光进行分束，得到第一子干涉光和第二子干涉光，以及用于对第二干涉光进行分束，得到第三子干涉光和第四子干涉光；第一子干涉光和第三子干涉光入射第一偏振耦合器，第二子干涉光和第四子干涉光入射第二偏振耦合器；第一偏振耦合器用于分别将第一子干涉光、第三子干涉光进行偏振分束，得到第一子干涉光的垂直分量和水平分量、第三子干涉光的垂直分量和水平分量；第一子干涉光的垂直分量和第三子干涉光的垂直分量分别入射第二光电转换单元，第一子干涉光的水平分量和第三子干涉光的水平分量分别入射第三光电转换单元；第二偏振耦合器用于分别将第二子干涉光、第四子干涉光进行偏振分束，得到第二子干涉光的垂直分量和水平分量、第四子干涉光的垂直分量和水平分量；第二子干涉光的垂直分量和第四子干涉光的垂直分量分别入射第二光电转换单元，第二子干涉光的水平分量和第四子干涉光的水平分量分别入射第三光电转换单元；第二光电转换单元用于对第一子干涉光的垂直分量和第二子 干涉光的垂直分量进行光电转换，得到第一电信号的垂直分量，以及用于对第三子干涉光的垂直分量和第四子干涉光的垂直分量进行光电转换，得到第二电信号的垂直分量；第三光电转换单元用于对第一子干涉光的水平分量和第二子干涉光的水平分量进行光电转换，得到第一电信号的水平分量，以及用于对第三子干涉光的水平分量和第四子干涉光的水平分量进行光电转换，得到第二电信号的水平分量。
第二方面，本申请实施例提供了一种偏振敏感型光学相干层析成像方法，包括：测量光源发出第一信号光和第二信号光；第一信号光入射参考臂，第二信号光入射样品臂；第一信号光入射参考臂后被调整为参考光，参考光射向偏振探测模块；第二信号光入射样品臂后被调整为样品光，部分样品光被第一部分反射单元反射向偏振探测模块，以与参考光相干形成第一干涉光，剩余样品光透过第一部分反射单元射向待测样品；待测样品将剩余样品光反射向偏振探测模块，以与参考光相干形成第二干涉光；第一干涉光经过偏振探测模块的处理产生第一电信号，第二干涉光经过偏振探测模块的处理产生第二电信号；控制模块根据第一电信号确定待测样品的表面光场信息，根据第二电信号确定待测样品的内部光场信息，并根据表面光场信息、内部光场信息确定待测样品的偏振特性，以根据偏振特性对待测样品进行成像。
从以上技术方案可以看出，本申请实施例具有以下优点：
在一般偏振敏感型光学相干层析成像***的基础上，通过在样品臂内部设置第一部分反射单元，将部分样品光在进入待测样品之前被反射回***，以获取样品光进入样品前的光场信息，从而可以更加准确快速地确定待测样品的偏振特性，最后形成较为准确的图像。该***基于硬件获取到样品光进入样品前的光场信息，降低数据处理的复杂度，排除了因样品表面位置定位不准确而导致的偏振特性计算不准确的问题，有助于PSOCT成像***的仪器化和在临床上的应用推广。同时目前的测量光源存在相位不稳定的问题，会影响数据处理的准确性，利用表面光场信息可以标定光源相位，获得稳定的相位有助于获得高质量的图像。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其它的附图。
图1为本申请一个实施例提供的偏振敏感型光学相干层析成像***的结构示意图；
图2为本申请一个实施例中扫描单元的结构示意图；
图3为本申请另一个实施例中扫描单元的结构示意图；
图4为本申请一个实施例中调整单元的结构示意图；
图5为本申请一个实施例中参考臂的结构示意图；
图6为本申请一个实施例中偏振探测模块的结构示意图；
图7为本申请另一个实施例提供的偏振敏感型光学相干层析成像***的结构示意图；
图8为本申请又一个实施例提供的偏振敏感型光学相干层析成像***的结构示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
第一方面，本申请实施例提供了一种偏振敏感型光学相干层析成像***，也可简称为PSOCT(Polarization-Sensitive Optical Coherence Tomography)成像***。PSOCT成像***可细分为单入射态PSOCT和多入射态PSOCT两种。前者通过精确控制照射到样品上光的偏振态，并探测反射光的偏振态变化来确定组织偏振特性，但由于光在光纤等光学器件里传播时偏振态会发生未知的变化，因此单入射态PSOCT只适用于自由空间结构，集成化能力和抗干扰能力较差，不利于仪器化。多入射态PSOCT 使用两束偏振状态正交的偏振光照射样品，并分别获得两束反射光的偏振态，消除光纤对偏振态的影响，最终得到样品的偏振特性。这种方法不需要严格控制入射光的偏振态，因此可以采取光纤结构的设计方案，只需极少的对准，操作和维护更容易且稳定性好，更适用于临床应用。而本申请中的PSOCT成像***也主要针对多入射态PSOCT。而入射待测物体的光线一方面会在待测样品表面被反射，另一方面会深入待测样品内部后被反射。在利用琼斯矩阵等分析方法求取待测样品的偏振信息时，这两部分的光场信息都需要确定。因此需要提取样品表面位置坐标，以此为基础再通过矩阵计算获得样品不同深度的偏振信息。目前主流方法是通过数字图像处理计算来分割组织边界，这种软件方法首先会减慢数据处理速度，其次对于不光滑的组织边界往往很难区分不同组织间界面位置，从而导致计算结果不准确，获得的偏振特性失真。
为了解决该问题，请参阅图1，图1中较粗且带有箭头的线条代表光线，其中虚线是代表在对应位置发生反射且最终被传输至偏振探测模块140的光线，而较细且不带有箭头的代表电连接。另外，图1中的箭头只代表光线在器件之间的关系，而并非光线在空间中的实际传播方向，光线在不同器件之间可以是基于光纤进行传播的，而非在自由空间中传播。本实施例中的成像***包括测量光源110、样品臂120、参考臂130、偏振探测模块140以及控制模块150。测量光源110用于将信号光分为第一信号光和第二信号光并发射，第一信号光入射参考臂130，第二信号光入射样品臂120。即在测量光源110内部，可以将信号光按照第一比例进行分光，分别得到进入样品臂120的第一信号光和进入参考臂130的第二信号光。第一比例可以为10％的第一信号光与90％的第二信号光。参考臂130用于将第一信号光调整为参考光后射向偏振探测模块140。参考光将于样品臂120对应的光在偏振探测模块140处汇合并发生干涉。在参考臂130内部一般设置有一对反射镜，通过改变反射镜之间的距离，可以改变参考臂130的长度，从而调整参考臂130与样品臂120之间的光程差，以调整干涉效果。
样品臂120包括调整单元121和扫描单元122。调整单元121用于将 第二信号光调整为样品光后射向扫描单元122。对于多入射态PSOCT而言，调整单元121所做的调整一般包括调整第二信号光的偏振态、将第二信号光调整为偏振方向正交的光信号，还可将这两束光信号通过时间复用、频率复用或深度复用区分开。
为了解决对待测样品10的表面标定困难且速度较慢的问题，考虑到扫描单元122射出的光线到待测样品10之间没有具有偏振特性的介质，可以在扫描单元122将光线发射至待测样品10前增加一个反射面，这一额外反射面返回的光场矩阵可以代替样品表面的光场矩阵，并以此计算样品的偏振特性。同时这一反射面还可以标定干涉光信号的相位，提高成像质量。
具体而言，扫描单元122设置有第一部分反射单元122A。第一部分反射单元122A为具有一定反射率的镜片结构，即部分样品光将被第一部分反射单元122A反射，没被反射的剩余样品光将通过第一部分反射单元122A射向待测样品10。例如，1％的样品光反射，剩余99％的光将透射至待测样品10。第一部分反射单元122A将部分样品光反射后，被反射的部分样品光应被传输至偏振探测模块140，与参考光在偏振探测模块140汇合并干涉，形成第一干涉光。而样品光中没被第一部分反射单元122A反射的剩余样品光将射入待测样品10，并在待测样品10内部发生反射，该被反射的剩余样品光应被传输至偏振探测模块140，与参考光在偏振探测模块140汇合并干涉，形成第二干涉光。图1中并未示出上述两个反射光与偏振探测模块140之间的关系，本申请中所说的反射向偏振探测模块140并非是光路直接指向偏振探测模块140，而可以是经过其他光学元件的传输，最终达到偏振探测模块140。例如，考虑部分样品光在第一部分反射单元122A处被反射会沿着样品光的入射方向传播，而剩余样品光在待测样品10处被反射后也会向着第一部分反射单元122A的方向原路返回，因此，可以在第一部分反射单元122A前设置光收集子单元，分别将这两个反射光收集，再通过光纤或者自由空间的形式传递至偏振探测模块140处。
偏振探测模块140用于对第一干涉光进行处理得到第一电信号，以及用于对第二干涉光进行处理得到第二电信号。为了便于进行数据处理，在偏振探测模块140至少可以进行光电转换处理，而如果采用琼斯矩阵的分 析方式，还可在光电转换前将第一干涉光或第二干涉光进行垂直分量和水平分量的分解等处理。控制模块150与偏振探测模块140连接，用于根据第一电信号确定待测样品10的表面光场信息，根据第二电信号确定待测样品10的内部光场信息，并根据表面光场信息、内部光场信息确定待测样品10的偏振特性，以根据偏振特性对待测样品10进行成像。
可以理解，在光学中，偏振光可以用琼斯矩阵表示，当光穿过光学元件时，通过取出光学元件的琼斯矩阵和入射光的琼斯矢量的乘积来找到出现的光的极化。将待测样品10本身也视为一个可用琼斯矩阵表示的光学元件，而第一干涉光和第二干涉光之间的差别即在于，第二干涉光经过待测样品10的作用而第一干涉光没有，比较这两个干涉光对应的光场信息之间的差异即可确定待测样品10的琼斯矩阵的相关信息，从而根据该相关信息确定待测样品10的偏振特性。基于准确的偏振特性对待测样品10形成的成像将更有利于对待测样品10的状态进行判断。第一部分反射单元122A的位置，反射率和形状可以根据需求自由调节成适合成像的参数。另外，测量光源110的相位稳定性会影响数据处理的准确性，利用表面光场信息可以标定光源相位，获得稳定的相位有助于获得高质量的图像。
基于本实施例中的偏振敏感型光学相干层析成像***，在一般偏振敏感型光学相干层析成像***的基础上，通过在样品臂120内部设置第一部分反射单元122A，将部分样品光在进入待测样品10之前被反射回***，以获取样品光进入样品前的光场信息，从而可以更加准确快速地确定待测样品10的偏振特性，最后形成较为准确的图像。本实施例基于硬件获取到样品光进入样品前的光场信息，降低数据处理的复杂度，排除了因样品表面位置定位不准确而导致的偏振特性计算不准确的问题，有助于PSOCT成像***的仪器化和在临床上的应用推广。同时目前的测量光源存在相位不稳定的问题，会影响数据处理的准确性，利用表面光场信息可以标定光源相位，获得稳定的相位有助于获得高质量的图像。
在其中一个实施例中，请参阅图2，扫描单元122包括振镜***122C和聚焦透镜122B。振镜***122C和聚焦透镜122B设置在调整单元121、第一部分反射单元122A之间的样品光的光路上。振镜***122C用于调整 样品光的方向，样品光经过方向调整后入射聚焦透镜122B。聚焦透镜122B对样品光进行聚焦，样品光经过聚焦后入射第一部分反射单元122A。可以理解，在成像时需要对待测样品10的多个位置进行扫描，通过控制振镜***122C，可改变样品光打在待测样品10上的位置，从而实现对待测样品10不同位置的扫描。对于图2所示的结构，在第一部分反射单元122A反射的部分样品光和在待测样品10处反射的剩余样品光均沿着图中较粗的黑线原路返回，可通过设置在振镜***122C前的光收集子单元收集这两个反射光，再传输至偏振探测模块140，以分别实现将将部分样品光反射向偏振探测模块140和将剩余样品光反射向偏振探测模块140。
在其中一个实施例中，请参阅图3，为了灵活的应对不同应用场景，第一部分反射单元122A可以至少由第一棱镜122A1和第一反射镜122A2组成。第一棱镜122A1用于接收样品光，将部分样品光反射向第一反射镜122A2，并将剩余样品光透射向待测样品10。第一反射镜122A2的位置可调，以改变与待测样品10的相对光程差，第一反射镜122A2用于将部分样品光反射向偏振探测模块140。这种设计可以通过调节第一反射镜122A2远离或接近第一棱镜122A1以控制反射面和样品之间相对的光程差。对于图3所示的结构，在第一棱镜122A1将部分样品光反射至第一反射镜122A2，第一反射镜122A2再将该部分样品光沿图3中较粗黑线原路反射回去，而在待测样品10处反射的剩余样品光均沿着图中较粗的黑线原路返回，可通过设置在振镜***122C前的光收集子单元收集这两个反射光，再传输至偏振探测模块140，以分别实现将将部分样品光反射向偏振探测模块140和将剩余样品光反射向偏振探测模块140。
本申请中大部分结构可采用光纤搭建，但为了方便调整光程，可以将样品臂120、参考臂130和照射待测样品10处设置为自由空间型。即测量光源110可通过光纤将第一信号光传递至参考臂130，还通过光纤将第二信号光传递至样品臂120。而样品臂120和参考臂130也分别通过光纤将光传递至偏振探测模块140。下面先对参考臂130进行说明。具体而言，在其中一个实施例中，对于多入射态PSOCT成像***而言，应由两个具有正交偏振态的光信号照射样品，即样品光包括两个偏振方向正交的光。 请参阅图4(图4中实线代表第二信号光或样品光，虚线代表被第一部分反射单元122A反射或被待测样品10反射的光)，调整单元121包括第一偏振控制器121D，偏振延迟单元121A、第一耦合器121B以及第一准直器121C。第二信号光入射偏振延迟单元121A前经过第一偏振控制器121D，第一偏振控制器121D用于调整第二信号光的偏振态为预设偏振态。在偏振延迟单元121A前利用第一偏振控制器121D的调节使生成的两个偏振方向正交的光信号强度相近，以保证成像质量。偏振延迟单元121A用于接收第二信号光，将第二信号光调整为两个偏振方向正交的光，以得到样品光，并将样品光射向第一耦合器121B。偏振延时单元即为光学领域常用的、将一个光分为两束偏振方向垂直的线偏振光的器件。而为分别获得其干涉谱的方法有多种，包括时分复用，频分复用和深度复用等等。由于样品光是两束光，而耦合器可以用于保证多组光信号的互相联通。而准直器是用于增大对光的输出或接收效率的一种输入输出元件，其可以保证扫描单元122和调整单元121之间传输的光有较大的效率。因此，样品光依次经第一耦合器121B耦合、第一准直器121C准直后可高效、准确射向扫描单元122。
样品光经扫描单元122的作用，部分样品光被第一部分反射单元122A反射，依次经过扫描单元122中第一部分反射单元122A之前的器件、第一准直器121C、第一耦合器121B后被传输至偏振探测模块140，偏振探测模块140处也可设置一耦合器来接收光，被反射的部分样品光和参考光在该耦合器处相干，产生第一干涉光。剩余样品光透过第一部分反射单元122A入射待测样品10，经待测样品10反射的剩余样品光依次经过扫描单元122、第一准直器121C、第一耦合器121B后被传输至偏振探测模块140，被反射的剩余样品光和参考光在偏振探测模块140处的耦合器相干，产生第二干涉光。
在其中一个实施例中，请参阅图5，参考臂130包括第二偏振控制器131、第二准直器132、参考臂长调节单元133、第三准直器134。第二偏振控制器131用于接收第一信号光，调整第一信号光的偏振态为预设偏振态，得到参考光，并将参考光射向第二准直器132。参考光经第二准直器 132准直后入射参考臂长调节单元133。参考臂长调节单元133包括第二反射镜和第三反射镜，第二反射镜和第三反射镜之间的距离可调，以调整参考臂长。参考光在第二反射镜和第三反射镜之间反射后入射第三准直器134，并经过第三准直器134准直后入射偏振探测模块140。具体而言，在参考臂130内光信号先由偏振控制器调节偏振态，再通过第二准直器132准直后，由一对反射镜反射，经过反射后光信号再由第三准直器134收集回光纤，然后达到偏振探测模块140，通过调节第二反射镜和第三反射镜之间的距离可以控制参考臂130的长度。
在其中一个实施例中，请参阅图6，偏振探测模块140包括第二耦合器141、第一偏振耦合器142、第二偏振耦合器143、第二光电转换单元144和第三光电转换单元145。第一部分反射单元122A反射的部分样品光和参考光在第二耦合器141相干形成第一干涉光，待测样品10反射的剩余样品光与参考光在第二耦合器141相干形成第二干涉光。第一干涉光和第二干涉光在第二耦合器141处形成后，第二耦合器141按照50：50的比例将其分束。在使用琼斯矩阵的方式进行分析时，一个干涉光包括两个正交的偏振态，将每个偏振态分为水平分量和垂直分量即可用一个2x2的矩阵表示干涉光，如下式所示：
Figure PCTCN2022135589-appb-000001
其中，E表示一个干涉光的光场信息，该干涉光包括E 1和E 2两个正交的偏振态。E H1为偏振态E 1的垂直分量，E V1为偏振态E 1的水平分量。E H2为偏振态E 2的垂直分量，E V2为偏振态E 2的水平分量。通过分别获取上面2x2矩阵中的所有元素，即可得到干涉光的光场信息。
先以第一干涉光的处理过程进行说明，第一干涉光被分为第一子干涉光和第二子干涉光。偏振耦合器可以将光分为垂直和竖直的两个分量光。第一子干涉光进入第一偏振耦合器142，得到第一子干涉光的垂直分量和水平分量。第二子干涉光进入第二偏振耦合器143，得到第二子干涉光的垂直分量和水平分量。第二光电转换单元144与垂直分量对应，第一子干涉光和第二干涉光的垂直分量均入射第二光电转换单元144，第二光电转换单元144对第一子干涉光的垂直分量和第二子干涉光的垂直分量进行光 电转换，得到第一电信号的垂直分量，即相当于得到第一干涉光对应的E H1和E H2。第三光电转换单元145与水平分量对应，第一子干涉光和第二干涉光的水平分量均入射第三光电转换单元145，第三光电转换单元145对第一子干涉光的水平分量和第二子干涉光的水平分量进行光电转换，得到第一电信号的水平分量，即相当于得到第一干涉光对应的E V1和E V2。控制模块150根据第一电信号的垂直分量和水平分量，即可确定第一干涉光的光场信息，而第一干涉光又是基于被第一部分反射单元122A反射的部分样品光生成的，控制模块150相当于确定了待测样品10的表面光场信息。
值得一提的是，这里并非是指电信号可以分为两个方向的分量，而是第一干涉光分别包括两个偏振态的垂直分量和竖直分量，第一电信号是由两个电信号组成的，其中一个与第一干涉光的两个偏振态的垂直分量对应，则称为第一电信号的垂直分量，另一个与第一干涉光的两个偏振态的水平分量对应，则称为第一电信号的水平分量。对于第二电信号也同样如此，后文不再赘述。
第二干涉光的处理过程类似，第二干涉光被分为第三子干涉光和第四子干涉光。第三子干涉光进入第一偏振耦合器142，得到第三子干涉光的垂直分量和水平分量。第四子干涉光进入第二偏振耦合器143，得到第四子干涉光的垂直分量和水平分量。第二光电转换单元144与垂直分量对应，第三子干涉光和第四干涉光的垂直分量均入射第二光电转换单元144，第二光电转换单元144对第三子干涉光的垂直分量和第四子干涉光的垂直分量进行光电转换，得到第二电信号的垂直分量，即相当于得到第二干涉光对应的E H1和E H2。第三光电转换单元145与水平分量对应，第三子干涉光和第四干涉光的水平分量均入射第三光电转换单元145，第三光电转换单元145对第三子干涉光的水平分量和第四子干涉光的水平分量进行光电转换，得到第二电信号的水平分量，即相当于得到第二干涉光对应的E V1和E V2。控制模块150根据第二电信号的垂直分量和水平分量，即可确定第二干涉光的光场信息，而第二干涉光又是基于被待测样品10反射的剩余样品光生成的，控制模块150相当于确定了待测样品10的内部光场信息。
在其中一个实施例中，在第一偏振耦合器142前可以设置第三偏振控 制器，在第二偏振耦合器143前可以设置第四偏振控制器。这两个偏振控制器均可用于保证生成的两个偏振态的光信号强度相近，以保证成像质量。
在其中一个实施例中，请参阅图7，***还包括时钟生成模块160，测量光源110包括光发射单元111、第一分光单元112和第二分光单元113。光发射单元111用于向第一分光单元112发射原始信号光。光发射单元111为最初的光源，其可以为扫频光源。第一分光单元112用于将原始信号光分为时钟信号光和信号光，其中，信号光的比例应远大于时钟信号光，如99：1。时钟信号光入射时钟生成模块160，信号光入射第二分光单元113。时钟信号光与信号光同源，因此可用于提取与信号光相关的时钟信号，以控制光发射单元111。具体而言，时钟生成模块160与控制模块150连接，用于根据时钟信号光生成与信号光对应的时钟信号并输出至控制模块150。第二分光单元113用于将信号光分为第一信号光和第二信号光。
在其中一个实施例中，时钟生成模块160包括干涉仪和第一光电转换单元。时钟信号光入射干涉仪并产生对应的相干光，第一光电转换单元用于将时钟信号光对应的相干光转换为时钟信号并输出至控制模块150。利用干涉仪产生时钟信号的技术较为成熟，在此不再赘述。在有些实施例中，干涉仪可以选择马赫曾德干涉仪。
以图8示出的详细的成像***对本申请中的光路再次进行说明。原始信号光由光发射单元111发出经过第一分光单元112将1％的光导入马赫曾德干涉仪161，相干光被光电探测器162采集用于产生时钟信号，并传导至控制模块150。光发射单元111出射的99％的光第二分光单元113分光，10％作为第一信号光进入参考臂130。90％作为第二信号光进入样品臂120。在参考臂130内光信号先由第二偏振控制器131调节偏振态，再通过第二准直器132准直后，由包含一对反射镜的参考臂长调节单元133反射，经过反射后光信号再由第三准直器134收集回光纤，然后达到第二耦合器141，通过调节第三反射镜、第四反射镜之间的距离可以控制参考臂的长度。
在样品臂光信号首先进入第一偏振控制器121D调整偏振态，再进入偏振延迟单元121A，利用偏振延迟单元121A可以将产生两个偏振方向正交的光信号，并将两者通过时间复用，频率复用或者深度复用区分开。这 两个偏振方向正交的光信号再经过第一耦合器121B，经过第一准直器121C进入扫描单元122，两个偏振方向正交的光在样品处反射。从扫描单元122返回的反射光光再由第一准直器121C收集，经耦合器121B，最后达到第二耦合器141，在第二耦合器141处和参考光分别发生相干，相干光在耦合器第二耦合器141后以50:50比例分束，然后再分别利用第一偏振耦合器142和第二偏振耦合器143将干涉光信号再分为两束偏振方向正交的分量，两个偏振耦合器的垂直分量端口接入第二光电转换单元144，水平分量输出端口接入第三光电转换单元145，通过调节第三偏振控制器146、第四偏振控制器147确保第一偏振耦合器142、第二偏振耦合器143输出信号的水平和垂直分量方向分别一致。两个光电转换单元将光信号转换为电信号，再由控制模块150采集并处理，并由控制模块150同步控制样品臂130的扫描。
而根据表面光场信息、内部光场信息确定待测样品的偏振特性具体可以为：首先定义偏振延迟单元121A的出口到扫描单元122中的第一部分反射单元处的琼斯矩阵为J in，第一部分反射单元到第二光电转化单元144或第三光电转换单元145的琼斯矩阵为J out，第一部分反射单元到待测样品内部某处再反射回第一部分反射单元的琼斯矩阵为J sample。由此，第一干涉光的光场可以表达为：
Figure PCTCN2022135589-appb-000002
其中，E in为偏振延迟单元121A处出射光的的光场信号，
Figure PCTCN2022135589-appb-000003
为第一相位因子。
第二干涉光的光场可以表达为：
Figure PCTCN2022135589-appb-000004
其中，
Figure PCTCN2022135589-appb-000005
为第二相位因子。这里的第一干涉光和第二干涉光的光场可根据第二光电转化单元144和第三光电转换单元155的输出确定。将上面两式相除可得到：
Figure PCTCN2022135589-appb-000006
Figure PCTCN2022135589-appb-000007
是第一相位因子对应相位和第二相位因子对应相位之间的相位差。J sample相似于一个对角矩阵，因此可以表示为：
Figure PCTCN2022135589-appb-000008
其中J C是对角矩阵，J A是酉矩阵。由此，可得：
Figure PCTCN2022135589-appb-000009
其中，J U＝J outJ A，所以J U也是酉矩阵，考虑到待测样品是具有双折射特性的材料而且J C是对角矩阵，因此上式可以转化为：
Figure PCTCN2022135589-appb-000010
其中，η是相位延迟。基于酉矩阵的特性，对
Figure PCTCN2022135589-appb-000011
这一矩阵求特征值，即可分别得到P 1e iη/2和P 2e -iη/2，由此可以求得待测样品的相位延迟和二向色性，即计算出待测样品的偏振特性。
第二方面，本申请实施例提供了一种偏振敏感型光学相干层析成像方法，包括：测量光源110发出第一信号光和第二信号光；第一信号光入射参考臂130，第二信号光入射样品臂120；第一信号光入射参考臂130后被调整为参考光，参考光射向偏振探测模块140；第二信号光入射样品臂120后被调整为样品光，部分样品光被第一部分反射单元122A反射向偏振探测模块140，以与参考光相干形成第一干涉光，剩余样品光透过第一部分反射单元122A射向待测样品10；待测样品10将剩余样品光反射向偏振探测模块140，以与参考光相干形成第二干涉光；第一干涉光经过偏振探测模块140的处理产生第一电信号，第二干涉光经过偏振探测模块140的处理产生第二电信号；控制模块150根据第一电信号确定待测样品10的表面光场信息，根据第二电信号确定待测样品10的内部光场信息，并根据表面光场信息、内部光场信息确定待测样品10的偏振特性，以根据偏振特性对待测样品10进行成像。关于该方法的说明可参照上文。
最后，还需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、 物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间可以根据需要进行组合，且相同相似部分互相参见即可。
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本申请。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本申请的精神或范围的情况下，在其它实施例中实现。因此，本申请将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

Claims (10)

  1. 一种偏振敏感型光学相干层析成像***，其特征在于，包括测量光源、样品臂、参考臂、偏振探测模块以及控制模块；
    所述测量光源用于将信号光分为第一信号光和第二信号光并发射，所述第一信号光入射所述参考臂，所述第二信号光入射所述样品臂；
    所述参考臂用于将所述第一信号光调整为参考光后射向所述偏振探测模块；
    所述样品臂包括调整单元和扫描单元，所述调整单元用于将所述第二信号光调整为样品光后射向所述扫描单元，所述扫描单元设置有第一部分反射单元，所述第一部分反射单元将部分样品光反射向所述偏振探测模块，以与所述参考光相干形成第一干涉光，所述第一部分反射单元将剩余样品光透射向待测样品；所述待测样品将所述剩余样品光反射向所述偏振探测模块，以与所述参考光相干形成第二干涉光；
    所述偏振探测模块用于对所述第一干涉光进行处理得到第一电信号，以及用于对所述第二干涉光进行处理得到第二电信号；
    所述控制模块与所述偏振探测模块连接，用于根据所述第一电信号确定所述待测样品的表面光场信息，根据所述第二电信号确定所述待测样品的内部光场信息，并根据所述表面光场信息、所述内部光场信息确定所述待测样品的偏振特性，以根据所述偏振特性对所述待测样品进行成像。
  2. 根据权利要求1所述的***，其特征在于，所述第一部分反射单元包括第一棱镜和第一反射镜；
    所述第一棱镜用于接收所述样品光，将所述部分样品光反射向所述第一反射镜，并将所述剩余样品光透射向所述待测样品；
    所述第一反射镜的位置可调，以改变与所述待测样品的相对光程差，所述第一反射镜用于将所述部分样品光反射向所述偏振探测模块。
  3. 根据权利要求1所述的***，其特征在于，所述扫描单元包括振镜***和聚焦透镜；所述振镜***和所述聚焦透镜设置在所述调整单元、所述第一部分反射单元之间的所述样品光的光路上；
    所述振镜***用于调整所述样品光的方向，所述样品光经过方向调整 后入射所述聚焦透镜；
    所述聚焦透镜对所述样品光进行聚焦，所述样品光经过聚焦后入射所述第一部分反射单元。
  4. 根据权利要求1所述的***，其特征在于，所述样品光包括两个偏振方向正交的光，所述调整单元包括偏振延迟单元、第一耦合器以及第一准直器；
    所述偏振延迟单元用于接收所述第二信号光，将所述第二信号光调整为两个偏振方向正交的光，以得到所述样品光，并将所述样品光射向所述第一耦合器；所述样品光依次经所述第一耦合器耦合、所述第一准直器准直后射向所述扫描单元。
  5. 根据权利要求4所述的***，其特征在于，所述调整单元还包括第一偏振控制器，所述第二信号光入射所述偏振延迟单元前经过所述第一偏振控制器，所述第一偏振控制器用于调整所述第二信号光的偏振态为预设偏振态。
  6. 根据权利要求1所述的***，其特征在于，所述参考臂包括第二偏振控制器、第二准直器、参考臂长调节单元、第三准直器；
    所述第二偏振控制器用于接收所述第一信号光，调整所述第一信号光的偏振态为预设偏振态，得到参考光，并将所述参考光射向所述第二准直器；所述参考光经所述第二准直器准直后入射所述参考臂长调节单元；
    所述参考臂长调节单元包括第二反射镜和第三反射镜，所述第二反射镜和所述第三反射镜之间的距离可调，以调整参考臂长；所述参考光在所述第二反射镜和所述第三反射镜之间反射后入射所述第三准直器，并经过所述第三准直器准直后入射所述偏振探测模块。
  7. 根据权利要求1所述的***，其特征在于，所述***还包括时钟生成模块，所述测量光源包括光发射单元、第一分光单元和第二分光单元；
    所述光发射单元用于向所述第一分光单元发射原始信号光；
    所述第一分光单元用于将原始信号光分为时钟信号光和所述信号光，所述时钟信号光入射所述时钟生成模块，所述信号光入射所述第二分光单元；
    所述时钟生成模块与所述控制模块连接，用于根据所述时钟信号光生成与所述信号光对应的时钟信号并输出至所述控制模块；
    所述第二分光单元用于将所述信号光分为所述第一信号光和第二信号光。
  8. 根据权利要求7所述的***，其特征在于，所述时钟生成模块包括干涉仪和第一光电转换单元；所述时钟信号光入射所述干涉仪并产生对应的相干光，所述第一光电转换单元用于将所述时钟信号光对应的相干光转换为所述时钟信号并输出至所述控制模块。
  9. 根据权利要求1所述的***，其特征在于，所述偏振探测模块包括第二耦合器、第一偏振耦合器、第二偏振耦合器、第二光电转换单元和第三光电转换单元；所述第一部分反射单元反射的所述部分样品光和所述参考光在所述第二耦合器相干形成所述第一干涉光，所述待测样品反射的所述剩余样品光与所述参考光在所述第二耦合器相干形成所述第二干涉光；
    所述第二耦合器用于对所述第一干涉光进行分束，得到第一子干涉光和第二子干涉光，以及用于对所述第二干涉光进行分束，得到第三子干涉光和第四子干涉光；所述第一子干涉光和所述第三子干涉光入射所述第一偏振耦合器，所述第二子干涉光和所述第四子干涉光入射所述第二偏振耦合器；
    所述第一偏振耦合器用于分别将所述第一子干涉光、所述第三子干涉光进行偏振分束，得到所述第一子干涉光的垂直分量和水平分量、所述第三子干涉光的垂直分量和水平分量；所述第一子干涉光的垂直分量和所述第三子干涉光的垂直分量分别入射所述第二光电转换单元，所述第一子干涉光的水平分量和所述第三子干涉光的水平分量分别入射所述第三光电转换单元；
    所述第二偏振耦合器用于分别将所述第二子干涉光、所述第四子干涉光进行偏振分束，得到所述第二子干涉光的垂直分量和水平分量、所述第四子干涉光的垂直分量和水平分量；所述第二子干涉光的垂直分量和所述第四子干涉光的垂直分量分别入射所述第二光电转换单元，所述第二子干涉光的水平分量和所述第四子干涉光的水平分量分别入射所述第三光电转 换单元；
    所述第二光电转换单元用于对所述第一子干涉光的垂直分量和所述第二子干涉光的垂直分量进行光电转换，得到所述第一电信号的垂直分量，以及用于对所述第三子干涉光的垂直分量和所述第四子干涉光的垂直分量进行光电转换，得到所述第二电信号的垂直分量；
    所述第三光电转换单元用于对所述第一子干涉光的水平分量和所述第二子干涉光的水平分量进行光电转换，得到所述第一电信号的水平分量，以及用于对所述第三子干涉光的水平分量和所述第四子干涉光的水平分量进行光电转换，得到所述第二电信号的水平分量。
  10. 一种偏振敏感型光学相干层析成像方法，其特征在于，包括：
    测量光源发出第一信号光和第二信号光；所述第一信号光入射参考臂，第二信号光入射样品臂；
    所述第一信号光入射参考臂后被调整为参考光，所述参考光射向偏振探测模块；
    所述第二信号光入射样品臂后被调整为样品光，部分样品光被第一部分反射单元反射向所述偏振探测模块，以与所述参考光相干形成第一干涉光，剩余样品光透过所述第一部分反射单元射向待测样品；所述待测样品将所述剩余样品光反射向所述偏振探测模块，以与所述参考光相干形成第二干涉光；
    所述第一干涉光经过所述偏振探测模块的处理产生第一电信号，所述第二干涉光经过所述偏振探测模块的处理产生第二电信号；
    控制模块根据所述第一电信号确定所述待测样品的表面光场信息，根据所述第二电信号确定所述待测样品的内部光场信息，并根据所述表面光场信息、所述内部光场信息确定所述待测样品的偏振特性，以根据所述偏振特性对所述待测样品进行成像。
PCT/CN2022/135589 2022-08-22 2022-11-30 偏振敏感型光学相干层析成像***、方法 WO2024040779A1 (zh)

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