WO2020200330A2 - 一种偏振成像方法及其装置、偏振成像系统 - Google Patents

一种偏振成像方法及其装置、偏振成像系统 Download PDF

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Publication number
WO2020200330A2
WO2020200330A2 PCT/CN2020/093460 CN2020093460W WO2020200330A2 WO 2020200330 A2 WO2020200330 A2 WO 2020200330A2 CN 2020093460 W CN2020093460 W CN 2020093460W WO 2020200330 A2 WO2020200330 A2 WO 2020200330A2
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Prior art keywords
polarization
sample
aperture
tested
standard sample
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PCT/CN2020/093460
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English (en)
French (fr)
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WO2020200330A3 (zh
Inventor
马辉
何宏辉
孟若愚
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清华-伯克利深圳学院筹备办公室
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Publication of WO2020200330A2 publication Critical patent/WO2020200330A2/zh
Publication of WO2020200330A3 publication Critical patent/WO2020200330A3/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/447—Polarisation spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J4/00—Measuring polarisation of light

Definitions

  • the embodiments of the present invention relate to the technical field of polarization imaging, and in particular to a polarization imaging method and device, and a polarization imaging system.
  • Polarization imaging technology is an advanced means of characterization. Its basic principle is to obtain some or all of the polarization state information of the measured light by measuring the different polarization components of the light. The polarization information can be obtained by analyzing and calculating these polarization information images. Parametric images, such as degree of polarization, polarization angle, ellipticity angle, polarization transmission characteristics, depolarization characteristics, etc., are used to analyze the shape, roughness, medium characteristics and even biochemical characteristics of the measured object.
  • the traditional polarization imaging method focuses the polarized light scattered through the sample to be measured by a collecting lens, and the focused polarized light is received by the detection device; the detection device analyzes and processes the received polarized light to obtain the required measurement Characteristic information of the sample.
  • the incident light on the object side of the collecting lens is parallel light, and the direction of the parallel light is parallel to the optical axis of the polarization imaging system lens.
  • the actual polarization imaging process not all incident light on the object side of the collecting lens is parallel light, and there are some non-parallel light at a certain angle with the optical axis of the collecting lens.
  • the embodiments of the present invention provide a polarization imaging method and device, and a polarization imaging system, which can improve the resolution and collection efficiency of polarization imaging without increasing polarization imaging errors.
  • an embodiment of the present invention provides a polarization imaging method, including:
  • the acquiring a polarization image of the sample to be tested according to the multiple second polarization properties and the multiple polarization property errors includes:
  • the multiple calibration polarization images are combined to obtain the polarization image of the sample to be tested.
  • both the first polarization attribute and the second polarization attribute include a Muller matrix.
  • an embodiment of the present invention also provides a polarization imaging device, including:
  • the first polarization attribute obtaining unit is used to control the polarized transmitted light beam after passing through the standard sample and the collection lens to pass through the aperture opening of the variable position to obtain multiple first polarization attributes of the standard sample;
  • a polarization attribute error obtaining unit configured to obtain multiple polarization attribute errors of the standard sample according to the multiple first polarization attributes and the standard polarization attribute of the standard sample;
  • the second polarization attribute acquiring unit is used to control the polarized transmitted light beam after passing through the sample to be tested and the collection lens to pass through the aperture through the aperture with a variable position to acquire multiple second polarization attributes of the sample to be tested;
  • the polarization image obtaining unit is configured to obtain the polarization image of the sample to be tested according to the plurality of second polarization properties and the errors of the plurality of polarization properties.
  • an embodiment of the present invention also provides a polarization imaging system, including: a focal plane filtering device and the above-mentioned polarization imaging device;
  • the focal plane filtering device includes a beam exit unit, a collection lens, an aperture, and a beam receiving unit arranged in sequence along the optical path; the sample or standard sample to be tested is placed between the beam exit unit and the collection lens;
  • the beam exit unit is used to provide a polarized incident beam and project it onto a sample to be tested or a standard sample;
  • the collecting lens is used to converge the polarized transmitted light beam that passes through the sample to be tested or the standard sample on the focal plane of the collecting lens;
  • the diaphragm is located on the focal plane of the collecting lens, and the diaphragm is used to control the polarized transmitted light beam condensed at a predetermined angle on the focal plane to pass through the focal plane; the diaphragm includes Aperture aperture
  • the light beam receiving unit is used to receive the polarized transmitted light beam passing through the focal plane
  • the focal plane filtering device further includes: a polarization analyzer
  • the analyzer unit is located in the optical path between the beam exit unit and the beam receiving unit; the sample to be tested or the standard sample is placed between the beam exit unit and the analyzer unit; The analyzer is used to modulate the polarization state of the polarized transmitted light beam passing through the sample to be tested or the standard sample.
  • the analyzer includes a first wave plate and a first polarizer that are sequentially arranged along the optical path;
  • the first wave plate and the first polarizer are arranged opposite to each other, and the polarized transmitted light beam that passes through the sample to be tested or the standard sample propagates through the first wave plate and the first polarizer in sequence.
  • the light beam exit unit includes a light source and a polarization subunit that are sequentially arranged along the light path;
  • the light source is used to provide parallel light of a specific wavelength
  • the polarizing subunit includes a second polarizer and a second wave plate that are arranged oppositely; the natural light is converted into a polarized incident beam through the second polarizer and the second wave plate in turn, and is projected to the sample to be tested or the second wave plate.
  • the standard sample is a first polarizer and a second wave plate that are arranged oppositely; the natural light is converted into a polarized incident beam through the second polarizer and the second wave plate in turn, and is projected to the sample to be tested or the second wave plate.
  • both the first wave plate and the second wave plate are quarter wave plates.
  • the center of the aperture through the aperture does not coincide with the focal point of the collecting lens.
  • the multiple first polarization properties of the standard sample and the standard polarization properties of the standard sample can obtain multiple corresponding polarization property errors; Error and multiple second polarization properties of the sample to be tested to obtain the polarization properties of the sample.
  • the position of the aperture through the aperture is changed, so that the polarized transmitted light beams in different angular ranges and/or different directions after the collecting lens can pass through the aperture through the aperture of the aperture to obtain the standard sample.
  • the first polarization properties and multiple second polarization properties of the sample to be tested, and multiple polarization attribute errors are obtained from the multiple first polarization properties of the standard sample and the standard properties of the standard sample, so that the difference in the sample to be tested can be obtained.
  • the polarization property error is used to calibrate the multiple second polarization properties of different angles, so as to reduce the obtained polarization property errors of the multiple second polarization properties, and improve the measurement
  • the resolution of the polarization image of the sample can obtain the anisotropy information of the sample to be tested, and the polarization imaging method is simple and low in cost.
  • FIG. 1 is a flowchart of a polarization imaging method provided by an embodiment of the present invention
  • FIG. 2 is a schematic top view of a structure in which the aperture of the diaphragm and the focal point of the collecting lens coincide with each other according to an embodiment of the present invention
  • FIG. 3 is a schematic side view of the structure in which the aperture of the diaphragm and the focal point of the collecting lens coincide with each other according to an embodiment of the present invention
  • FIG. 4 is a schematic top view of a structure in which the focal point of the aperture through the aperture and the focal point of the collecting lens do not overlap according to an embodiment of the present invention
  • FIG. 5 is a schematic side view of a structure in which the focal point of the aperture through the aperture and the focal point of the collecting lens do not overlap according to an embodiment of the present invention
  • FIG. 6 is a flowchart of a polarization image synthesis method provided by an embodiment of the present invention.
  • FIG. 7 is a structural block diagram of a polarization imaging device according to an embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of a polarization imaging system provided by an embodiment of the present invention.
  • FIG. 9 is a schematic structural diagram of a focal plane filtering device provided by an embodiment of the present invention.
  • FIG. 10 is a schematic structural diagram of another focal plane filter device provided by an embodiment of the present invention.
  • the optical inspection method can perform high-resolution non-destructive inspection of the sample to be tested without contact, the optical inspection method has a very wide range of applications in the measurement field.
  • the intensity information and polarization properties of the polarized light beam after passing through the sample are obtained to obtain the microstructure information of the sample.
  • a polarization imaging method which can image polarized light passing through a sample.
  • the polarization imaging method can be executed by the polarization imaging device provided in the embodiment of the present invention, and the device can be implemented by software and/or hardware.
  • Fig. 1 is a flowchart of a polarization imaging method provided by an embodiment of the present invention. As shown in Fig. 1, the polarization imaging method provided by the embodiment of the present invention includes:
  • the polarized incident light beam transmitted through the standard sample is scattered in various directions, and the polarized transmitted light beams in different directions carry different microstructure information of the standard sample.
  • the polarized transmitted light beam passing through the sample is condensed on the focal plane of the collecting lens after passing through the collecting lens, and the polarized transmitted light beam condensed on the focal plane of the collecting lens is spatially filtered by the diaphragm on the focal plane. Since the position of the aperture of the aperture can be adjusted, the position of the aperture of the aperture can be adjusted by rotating around the optical axis of the aperture or changing along the radial direction of the aperture.
  • the aperture of the diaphragm can spatially filter the polarized transmitted light beams in different angle ranges and/or different directions.
  • the position of the aperture of the diaphragm when the position of the aperture of the diaphragm is constantly changing, it can be used for different angle ranges and /Or the polarized transmitted light beams in different directions are spatially filtered to obtain a plurality of polarized transmitted light beams in different angle ranges and/or different directions.
  • the multiple first polarization properties of the standard sample can be obtained.
  • the multiple first polarization properties of the standard sample may include, for example, multiple Mueller matrices corresponding to polarized transmitted light beams in different directions.
  • the stocks vector S of the incident polarized beam is:
  • the polarization state of the polarized transmission beam passing through the standard sample is represented by the stocks vector S1, and M represents the Mueller matrix of the polarized beam before and after passing through the standard sample, as follows:
  • the diaphragm located on the focal plane of the collection lens has a diaphragm through hole, and the center of the diaphragm through hole and the focal point of the collection lens may or may not coincide.
  • the structure of the diaphragm is circular, the position of the aperture of the adjustable diaphragm changes along the radial direction of the diaphragm.
  • the diaphragm can spatially filter the polarized transmitted light beams in different angular ranges.
  • 2 is a schematic top view of the structure of an aperture through the diaphragm according to an embodiment of the present invention that changes along the radial direction of the aperture, and FIG.
  • FIG. 3 is a schematic diagram of the aperture along the diameter of the aperture provided by the embodiment of the present invention. Schematic diagram of the side view structure changing to the direction.
  • the position of the aperture through the diaphragm may be any one of the first position 111, the second position 112, and the third position 113.
  • the aperture through hole when the aperture through hole is at the first position 111, the aperture through hole is a circular hole with a radius of r1, which can spatially filter the polarized transmitted light beam in the first angular range to obtain the first angular range The first polarization property of the polarized transmitted light beam; when the aperture through hole is located at the second position 112, the aperture through hole is a ring of r2-r1, which can transmit the polarized light beam in the second angular range Spatial filtering is performed to obtain the corresponding first polarization attribute of the polarized transmitted light beam in the second angular range; when the diaphragm opening is at the third position 113, the diaphragm opening is a ring of r3-r2.
  • the polarized transmitted light beam in the third angle range may be spatially filtered, so as to obtain the corresponding first polarization property of the polarized transmitted light beam in the third angle range.
  • the values of r1, r2-r1 and r3-r2 may be the same or different.
  • FIG. 4 is a schematic top view of the structure of an aperture through the aperture and the focus of the collecting lens provided by an embodiment of the present invention
  • FIG. 5 is a schematic view of the aperture through the aperture and the focus of the collection lens provided by an embodiment of the present invention.
  • Schematic diagram of overlapping side structure. 4 and 5 the center O'of the aperture through hole 11 does not coincide with the focal point O of the collecting lens, and the aperture through hole 11 rotates around the aperture axis X1, so that the polarized transmitted beams in different directions can pass through the light Stop through the light hole 11.
  • the range of the polarized transmitted light beam passing through the diaphragm through hole 11 is
  • the diaphragm opening 11 is at the initial position, the direction of the polarized transmitted light beam passing through the diaphragm opening 11 is ⁇ 2 ⁇ 1; rotate the diaphragm opening 11 around the diaphragm axis X1 by an angle of ⁇ to pass The direction of the polarized light beam transmitted through the aperture 11 becomes ⁇ 3 to ⁇ 4.
  • the aperture opening 11 can be rotated around the aperture axis X1 by a multiple of ⁇ to obtain polarized transmitted light beams in different directions.
  • multiple first polarization properties corresponding to polarized transmitted light beams with different angular ranges and/or different polarization directions can be obtained by changing the position of the aperture through the aperture.
  • S120 Acquire multiple polarization attribute errors of the standard sample according to the multiple first polarization attributes and the standard polarization attribute of the standard sample.
  • the standard sample is also called the physical standard, which together with the written standard constitutes the standard value.
  • the standard polarization properties of the standard sample can reflect the microstructure information of the standard sample.
  • the polarization properties are compared, and the deviation of the measured multiple first polarization properties from the standard polarization properties can be obtained, which is the polarization property error of the standard sample.
  • the polarization attribute error corresponding to each first polarization attribute is different, and the polarization attribute error of the standard sample can be used as the calibration error during polarization imaging.
  • the standard polarization property may be the standard Mueller matrix of the standard sample
  • the first polarization property may include the measured Mueller matrix
  • the obtained polarization property error is that the Mueller matrix of the first polarization property is relative to the standard Mueller matrix. The deviation of the matrix.
  • S130 Control the polarized transmitted light beam after passing through the sample to be tested and the collecting lens to pass through the aperture through the aperture that rotates around the optical axis of the aperture to obtain multiple second polarization properties of the sample to be tested.
  • the polarized incident light beam transmitted through the sample to be tested is scattered in various directions, and the polarized transmitted light beams in different directions carry different microstructure information of the sample to be tested.
  • the polarized transmitted light beam passing through the sample to be tested is condensed on the focal plane of the collecting lens after passing through the collecting lens, and the polarized transmitted light beam condensed on the focal plane of the collecting lens is spatially filtered by the diaphragm on the focal plane. Since the position of the aperture of the aperture can be adjusted, the position of the aperture of the aperture can be adjusted by rotating around the optical axis of the aperture or changing along the radial direction of the aperture.
  • the aperture of the diaphragm can be used for different angle ranges and/or different directions.
  • the position of the aperture of the diaphragm when the position of the aperture of the diaphragm is constantly changing, it can be used for different angle ranges and/or different directions through the sample to be tested.
  • the polarized transmitted light beam is spatially filtered to obtain a plurality of polarized transmitted light beams in different angle ranges and/or different directions.
  • the to-be-tested can be obtained Multiple first polarization properties of the sample.
  • the multiple second polarization properties of the sample to be tested may include, for example, multiple Mueller matrices corresponding to polarized transmitted light beams in different directions.
  • the polarization state of the polarized transmission beam passing through the sample to be tested is represented by the stocks vector S2, and M'represents the Mueller matrix of the polarized light passing through the sample to be tested, as follows:
  • the multiple second polarization properties of the sample to be tested are obtained in the same manner as the multiple first polarization properties of the standard sample.
  • FIGS. 2, 3, 4, and 5 are only schematic diagrams of the diaphragm structure of the embodiment of the present invention.
  • the diaphragm aperture can control the polarization transmission of different angle ranges and/or different directions
  • the structure of the aperture and the aperture of the aperture, and the position change form of the aperture of the aperture are not specifically limited.
  • the aperture through the aperture when the aperture through the aperture is located at the first position 11, the center of the aperture through the aperture 111 coincides with the focal point O of the collecting lens, the aperture at the first position 111 through
  • the size of the aperture r1 can be limited to a small range, and it can be considered that the polarized transmitted light beam passing through the aperture 11 of the aperture 10 is a polarized transmitted light beam perpendicular to the focal plane S of the collecting lens; or, according to actual conditions In this case, the size r1 of the aperture through the first position 111 is limited, and the first polarization property of the standard sample and the second polarization property of the sample to be tested are correspondingly obtained.
  • S140 Acquire a polarization image of the sample to be tested according to the plurality of second polarization properties and errors of the plurality of polarization properties.
  • a polarized imaging system is equipped with a collecting lens to collect the polarized transmitted light beam after the polarized incident light beam passes through the sample to be tested.
  • the larger the numerical aperture NA of the collecting lens the stronger the light-absorbing ability of the collecting lens, and the collected polarized transmitted light beam The higher the resolution after imaging.
  • the numerical aperture of the collecting lens is determined by the refractive index n of the medium between the collecting lens and the sample to be measured and the half of the aperture angle 2 ⁇ , that is, the numerical aperture NA is:
  • D is the diameter of the collecting lens
  • f is the focal length of the collecting lens.
  • ⁇ is the wavelength of the polarized beam.
  • NA the numerical aperture of the collecting lens.
  • increasing the numerical aperture of the collecting lens increasing the diameter D of the collecting lens or reducing the focal length f of the collecting lens will inevitably cause more polarization transmission of optical elements that are not perpendicular to the polarization imaging system. beam. In this way, the error of polarization imaging will be further increased and the accuracy of measurement information will be reduced.
  • the second polarization attributes corresponding to the polarized transmission beams in different angle ranges can be calibrated, so that the multiple second polarization attributes after the calibration can be passed.
  • the polarization imaging resolution can be improved under the premise of improving the polarization imaging resolution.
  • Reduce the polarization imaging error when the polarization property error is the error corresponding to the polarization transmission beams in different directions, the second polarization properties corresponding to the polarization transmission beams in different directions can be calibrated, so that the second polarization properties can be calibrated after passing the calibration.
  • the anisotropy information of the sample to be tested can be obtained, which can enrich the structure information of the sample to be tested, and further increase the accuracy of the polarization imaging of the sample to be tested.
  • the position of the aperture through the aperture is changed, so that the polarized transmitted light beams in different angular ranges and/or different directions after the collecting lens can pass through the aperture through the aperture of the aperture to obtain the standard sample.
  • the first polarization properties and multiple second polarization properties of the sample to be tested, and multiple polarization attribute errors are obtained from the multiple first polarization properties of the standard sample and the standard properties of the standard sample, so that the difference in the sample to be tested can be obtained.
  • the polarization property error is used to calibrate the multiple second polarization properties of different angles, so as to reduce the obtained polarization property errors of the multiple second polarization properties, and improve the measurement
  • the resolution of the polarization image of the sample can obtain the anisotropy information of the sample to be tested, and the polarization imaging method is simple and low in cost.
  • the method for obtaining the polarization image of the sample to be tested according to the plurality of second polarization properties and the plurality of polarization property errors specifically includes: according to the plurality of polarization properties The error corresponds to calibrating the plurality of second polarization properties to obtain a plurality of calibration polarization properties; according to the plurality of calibration polarization properties, obtaining a plurality of calibration polarization images; combining the plurality of calibration polarization images to obtain the test Polarization image of the sample.
  • Fig. 6 is a flowchart of a polarization image synthesis method provided by an embodiment of the present invention. As shown in Figure 6, the method includes:
  • multiple second polarization properties of the sample to be tested can be correspondingly obtained. Since the angle range and/or direction of the polarized transmission beams corresponding to the multiple second polarization properties of the sample to be tested are the same as the angle ranges and/or directions of the polarized transmission beams corresponding to the multiple first polarization properties of the standard sample, it can be According to the multiple first polarization properties of the standard sample and the multiple polarization property errors corresponding to the standard polarization properties, multiple second polarization properties are calibrated correspondingly, and multiple calibrated polarizations after the multiple second polarization properties of the test sample are obtained. Attributes.
  • a polarization image of the sample to be tested can be obtained, that is, the calibration polarization image.
  • the multiple calibrated polarization images obtained by multiple calibrated polarization properties are combined into one polarization image, and the combined polarization image is the polarization image of the sample to be tested.
  • a high-resolution polarization image can be obtained by obtaining a plurality of second polarization properties obtained by a plurality of polarized transmitted beams of different angle ranges; in the second aspect, by calibrating a plurality of second polarization properties, The obtained high-resolution polarization image has smaller errors and higher accuracy; thirdly, the multiple second polarization properties obtained by multiple polarized transmitted beams in different directions can obtain the various directions of the sample to be tested. Information of the opposite sex.
  • FIG. 7 is a structural block diagram of a polarization imaging device provided by an embodiment of the present invention.
  • the polarization imaging device of the embodiment of the present invention includes: a first polarization property acquisition unit 101, a polarization property error acquisition unit 102, a second polarization property acquisition unit 103 and a polarization image acquisition unit 104.
  • the first polarization attribute obtaining unit 101 is used to control the polarized transmitted light beam after passing through the standard sample and the collection lens to pass through the aperture through the aperture with a variable position, so as to obtain multiple first polarization attributes of the standard sample;
  • the polarization attribute error obtaining unit 102 is configured to obtain multiple polarization attribute errors of the standard sample according to the multiple first polarization attributes and the standard polarization attribute of the standard sample;
  • the second polarization attribute obtaining unit 103 is used to control the polarized transmitted light beam after passing through the sample to be tested and the collection lens to pass through the aperture through the aperture with a variable position to obtain multiple second polarization attributes of the sample to be tested;
  • the polarization image obtaining unit 104 is configured to obtain a polarization image of the sample to be tested according to the plurality of second polarization properties and errors of the plurality of polarization properties.
  • the position of the aperture through the aperture is changed, so that the polarized transmitted light beams in different angular ranges and/or different directions after the collecting lens can pass through the aperture through the aperture of the aperture to obtain the standard sample.
  • the first polarization properties and multiple second polarization properties of the sample to be tested, and multiple polarization attribute errors are obtained from the multiple first polarization properties of the standard sample and the standard properties of the standard sample, so that the difference in the sample to be tested can be obtained.
  • the polarization property error is used to calibrate the multiple second polarization properties of different angles, so as to reduce the obtained polarization property errors of the multiple second polarization properties, and improve the measurement
  • the resolution of the polarization image of the sample can obtain the anisotropy information of the sample to be tested, and the polarization imaging method is simple and low in cost.
  • the polarization imaging device provided by the embodiment of the present invention can execute the polarization imaging method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects for executing the method.
  • polarization imaging method provided in any embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of a polarization imaging system provided by an embodiment of the present invention.
  • the polarization imaging system includes a focal plane filter device 100 and a polarization imaging device 200 provided by an embodiment of the present invention; wherein, the focal plane filter device 100 includes a beam exit unit 20, a collection lens 30, and a diaphragm arranged in sequence along the optical path.
  • the sample 50 or standard sample 60 to be tested is placed between the beam exit unit 20 and the collection lens 30; the beam exit unit 20 is used to provide a polarized incident light beam and project it to the sample 50 or standard sample 60 to be tested
  • the collection lens 30 is used to converge the polarized transmitted light transmitted through the sample 50 or the standard sample 60 on the focal plane S of the collection lens 30; the diaphragm 10 is located on the focal plane S of the collection lens 30, the diaphragm 10 is used to control the polarized transmitted light condensed at a preset angle on the focal plane S to pass through the focal plane S; the diaphragm 10 includes an aperture through hole; the beam receiving unit 40 is used to receive the polarized transmitted light that passes through the focal plane S .
  • the polarized incident light beam provided by the beam exit unit 20 passes through the sample 50 or the standard sample 60 and the polarized transmitted light beam is condensed on the focal plane S of the collecting lens 30 through the collecting lens 30; the diaphragm is arranged on the focal plane S 10 Perform spatial filtering on the polarized transmitted light beam condensed at the focal plane S of the collecting lens 30, so that the polarized transmitted light at a predetermined angle passes through the focal plane S; the beam receiving unit 40 receives the polarized light at a predetermined angle passed through the focal plane S Transmit the light beam, and send the polarized transmitted light beam with the preset angle to the polarization imaging device 200, which can obtain the corresponding second polarization attribute or standard sample of the test sample 50 according to the polarized transmitted light beam with the preset angle 60 first polarization properties.
  • the position of the aperture of the aperture 10 can be adjusted by rotating around the optical axis of the aperture 10 or along the radial direction of the aperture 10. It changes, and the aperture through holes at different positions can spatially filter the polarized transmitted light beams with preset angles in different angle ranges and/or different directions, so as to obtain polarized transmitted light beams in different angle ranges and/or different directions.
  • the aperture through holes at different positions can spatially filter the polarized transmitted light beams with preset angles in different angle ranges and/or different directions, so as to obtain polarized transmitted light beams in different angle ranges and/or different directions.
  • multiple second polarization properties of the sample 50 to be tested or multiple first polarization properties of the standard sample 60 can be obtained.
  • the center of the aperture opening of the optional aperture 10 does not coincide with the focal point O of the collecting lens 30.
  • the plurality of second polarization properties and the plurality of first polarization properties may each include, for example, multiple Mueller matrices corresponding to polarized transmitted light beams in different angle ranges and/or different directions.
  • multiple polarization property errors of the polarization imaging system during polarization imaging can be obtained, and the obtained multiple second polarization properties of the test sample 50 can be obtained.
  • Corresponding calibration of the polarization property error can obtain more accurate multiple calibration polarization properties, and multiple calibration polarization images can be obtained from the multiple calibration polarization properties.
  • the test sample 50 can be obtained. Polarized images, thereby obtaining the microstructure of the sample 50 to be tested.
  • an aperture is set on the focal plane of the collecting lens, so that the polarized transmitted light with a preset angle in the polarized transmitted light passing through the sample or standard sample can pass through the focal plane of the collecting lens, thereby changing the focal plane of the aperture.
  • the position of the aperture of the diaphragm can obtain the polarization properties corresponding to the polarized transmitted light in different angle ranges and/or different directions.
  • the polarization property error of the standard sample is used to calibrate the polarization property of the sample to be tested, which can make the polarization image of the sample to be tested have a higher accuracy; on the other hand, through multiple different angle ranges and/or different polarization directions
  • the polarized images of the test sample synthesized by the polarized transmitted light have a higher resolution, and the anisotropy information of the test sample can be obtained.
  • FIG. 9 is a schematic structural diagram of a focal plane filtering device according to an embodiment of the present invention.
  • the focal plane filter device 100 further includes: an analyzer 70; the analyzer 70 is located in the optical path between the beam exit unit 20 and the beam receiving unit 40; the sample 50 or The standard sample 60 is placed between the beam exit unit 20 and the analyzer unit 70; the analyzer unit 70 is used to adjust the polarization state of the polarized transmitted light beam passing through the test sample 50 or the standard sample 60.
  • the analyzer 70 may optionally include a first wave plate 71 and a first polarizer 72 arranged in sequence along the optical path; the first wave plate 71 and the first polarizer 72 are arranged opposite to each other, and pass through the sample 50 or standard sample under test The 60 polarized transmitted light beam propagates through the first wave plate 71 and the first polarizer 72 in sequence.
  • the analyzer 70 is located in the optical path between the beam exit unit 20 and the beam receiving unit 40, and the analyzer 70 may be located in the optical path between the beam exit unit 20 and the collection lens 30; or, the analyzer The polarization unit 70 may also be located in the optical path between the collection lens 30 and the aperture 10; or, the analyzer unit 70 may also be located in the optical path between the aperture 10 and the receiving unit.
  • FIG. 9 exemplarily takes the analyzer 70 located in the optical path between the collection lens 30 and the diaphragm 10 as an example for description. The technical principle when the analyzer 70 is located at other positions is similar to the technical principle shown in FIG. 9, and will not be repeated here.
  • the polarized incident light beam provided by the beam exit unit 20 passes through the sample 50 or the standard sample 60 to be tested, and the polarized transmitted light passing through the sample 50 or the standard sample 60 undergoes polarization state changes when passing through the analyzer unit 70. Adjustment. By rotating the first wave plate 71 of the analyzer unit 70, the polarization state of the polarized transmitted light passing through the analyzer unit 70 can be changed.
  • the first wave plate 71 may be a quarter wave plate.
  • FIG. 10 is a schematic structural diagram of another focal plane filtering device provided by an embodiment of the present invention.
  • the beam exit unit 20 of the focal plane filter device 100 includes a light source 21 and a polarization subunit 22 arranged in sequence along the optical path; the light source 21 is used to provide parallel light of a specific wavelength; the polarization subunit 22 includes a second polarized oppositely arranged Plate 221 and second wave plate 222; natural light is converted into a polarized incident beam through the second polarizer 221 and second wave plate 222 in turn, and is projected to the sample 50 or standard sample 60 to be tested.
  • the polarized incident beam provided by the beam exit unit 20 has a certain polarization direction, and the polarization direction of the second wave plate 222 relative to the second polarizer 221 can be controlled by light to obtain polarized incident beams with different polarization directions.
  • the second wave plate 222 may be a quarter wave plate.
  • the second wave plate 222 can be combined with the first wave plate 71 to measure the polarized transmitted light with different polarization directions.
  • the position of the aperture passing light is changed so that the polarized transmitted light beams in different angle ranges and/or different directions after passing through the collecting lens can pass through the aperture
  • the aperture passes through the aperture to obtain multiple first polarization properties of the standard sample and multiple second polarization properties of the sample to be tested, and obtain multiple polarizations from the multiple first polarization properties of the standard sample and the standard properties of the standard sample Attribute error, so that after obtaining multiple second polarization attributes of different angles of the sample to be tested, the polarization attribute error can calibrate the multiple second polarization attributes of different angles to reduce the obtained multiple second polarization attributes.
  • the resolution of the polarization image of the sample to be tested is improved, the anisotropy information of the sample to be tested is obtained, and the polarization imaging method is simple and low in cost.

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Abstract

本发明实施例公开了一种偏振成像方法及其装置、偏振成像系统，该偏振成像方法通过变化光阑通光孔的位置，以使经收集透镜后的不同角度范围和/或不同方向的偏振透射光束透过光阑的光阑通光孔，以获得标准样品的多个第一偏振属性和待测样品的多个第二偏振属性，并由标准样品的多个第一偏振属性与标准样品的标准属性得到多个偏振属性误差，从而能够在获得待测样品的不同角度的多个第二偏振属性后，由偏振属性误差对不同角度的多个第二偏振属性进行校准，以在降低所获得的多个第二偏振属性的偏振属性误差的前提下，提高待测样品偏振图像的分辨率，获得待测样品的各向异性信息，并且偏振成像方法简单，成本低。

Description

一种偏振成像方法及其装置、偏振成像系统 技术领域
本发明实施例涉及偏振成像技术领域，尤其涉及一种偏振成像方法及其装置、偏振成像系统。
背景技术
偏振成像技术是一种先进的表征手段，其基本原理是通过测量光线不同的偏振分量，进而得到被测光线的部分或全部偏振状态信息，并对这些偏振信息图像的分析和计算，可以获得偏振参数图像，如偏振度、偏振角、椭圆率角、偏振传输特性、去偏特性等，以用于分析被测物的形状、粗糙度、介质特性甚至生物化学等各项特征信息。
传统的偏振成像方法通过收集透镜使透过待测样品散射的偏振光聚焦，聚焦后的偏振光被检测装置接收；检测装置通过对所接收的偏振光进行分析处理，以获得所需的待测样品的特征信息。在检测装置的分析处理过程中通常会假设收集透镜物侧的入射光为平行光，且该平行光的方向与偏振成像系统透镜的光轴平行。但在实际的偏振成像过程中，收集透镜物侧的入射光并非都为平行光，还有一些与收集透镜的光轴呈一定角度的非平行光，该非平行光的存在会引入检测误差；并且在提高偏振成像的分辨率时，需要增大收集透镜的直径或减小收集透镜焦距的，以增大收集透镜的数值孔径，如此将会进一步增加偏振成像的误差。
发明内容
针对上述存在问题，本发明实施例提供一种偏振成像方法及其装置、偏振成像系统，能够在不增加偏振成像误差的前提下，提高偏振成像的分辨率和收集效率。
第一方面，本发明实施例提供了一种偏振成像方法，包括：
控制经标准样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取标准样品的多个第一偏振属性；
根据所述多个第一偏振属性以及所述标准样品的标准偏振属性获取所述标准样品的多个偏振属性误差；
控制经待测样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取待测样品的多个第二偏振属性；
根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像。
可选的，所述根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像包括：
根据所述多个偏振属性误差对应校准所述多个第二偏振属性，获取多个校准偏振属性；
根据所述多个校准偏振属性，获取多个校准偏振图像；
合并所述多个校准偏振图像，以获取所述待测样品的偏振图像。
可选的，所述第一偏振属性、所述第二偏振属性均包括穆勒矩阵。
第二方面，本发明实施例还提供了一种偏振成像装置，包括：
第一偏振属性获取单元，用于控制经标准样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取标准样品的多个第一偏振属性；
偏振属性误差获取单元，用于根据所述多个第一偏振属性以及所述标准样品的标准偏振属性获取所述标准样品的多个偏振属性误差；
第二偏振属性获取单元，用于控制经待测样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取待测样品的多个第二偏振属性；
偏振图像获取单元，用于根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像。
第三方面，本发明实施例还提供了一种偏振成像系统，包括：焦平面滤波装置和上述偏振成像装置；
所述焦平面滤波装置包括沿光路依次设置的光束出射单元、收集透镜、光阑和光束接收单元；待测样品或标准样品放置于所述光束出射单元和所述收集透镜之间；
所述光束出射单元用于提供偏振入射光束，并投射至待测样品或标准样品上；
所述收集透镜用于将透过所述待测样品或所述标准样品的偏振透射光束会聚于所述收集透镜的焦平面上；
所述光阑位于所述收集透镜的焦平面上，所述光阑用于控制会聚于所述焦平面上的预设角度的所述偏振透射光束透过所述焦平面；所述光阑包括光阑通光孔；
所述光束接收单元用于接收透过所述焦平面的所述偏振透射光束
可选的，所述焦平面滤波装置还包括：检偏单元；
所述检偏单元位于所述光束出射单元与所述光束接收单元之间的光路中；所述待测样品或所述标准样品放置于所述光束出射单元和所述检偏单元之间；所述检偏单元用于调制透过所述待测样品或所述标准样品的偏振透射光束的偏振状态。
可选的，所述检偏单元包括沿光路依次设置的第一波片和第一偏振片；
所述第一波片与所述第一偏振片相对设置，透过所述待测样品或所述标准样品的偏振透射光束依次经所述第一波片和第一偏振片传播。
可选的，所述光束出射单元包括沿所述光路依次设置的光源、偏振子单元；
所述光源用于提供特定波长的平行光；
所述偏振子单元包括相对设置的第二偏振片和第二波片；所述自然光依次经过所述第二偏振片和第二波片转换为偏振入射光束，投射至所述待测样品或所述标准样品。
可选的，所述第一波片与所述第二波片均为1/4波片。
可选的，所述光阑通光孔的中心与所述收集透镜的焦点不重合。
本发明实施例提供的偏振成像方法及其装置、偏振成像系统，通过标准样品的多个第一偏振属性和标准样品的标准偏振属性，能够获得对应的多个偏振属性误差；由多个偏振属性误差和待测样品的多个第二偏振属性，获得样品的偏振属性。本发明实施例通过变化光阑通光孔的位置，以使经收集透镜后的不同角度范围和/或不同方向的偏振透射光束透过光阑的光阑通光孔，以获得标准样品的多个第一偏振属性和待测样品的多个第二偏振属性，并由标准样品的多个第一偏振属性与标准样品的标准属性得到多个偏振属性误差，从而能够在获得待测样品的不同角度的多个第二偏振属性后，由偏振属性误差对不同角度的多个第二偏振属性进行校准，以在降低所获得的多个第二偏振属性的偏振属性误差的前提下，提高待测样品偏振图像的分辨率，获得待测样品的各向异性信息，并且偏振成像方法简单，成本低。
附图说明
图1是本发明实施例提供的一种偏振成像方法的流程图；
图2是本发明实施例提供的一种光阑通光孔与收集透镜的焦点重合的俯视结构示意图；
图3是本发明实施例提供的一种光阑通光孔与收集透镜的焦点重合的侧视结构示意图；
图4是本发明实施例提供的一种光阑通光孔与收集透镜的焦点不重合的俯视结构示意图；
图5是本发明实施例提供的一种光阑通光孔与收集透镜的焦点不重合的侧视结构示意图；
图6是本发明实施例提供的偏振图像合成方法的流程图；
图7是本发明实施例提供的一种偏振成像装置的结构框图；
图8是本发明实施例提供的一种偏振成像系统的结构示意图；
图9是本发明实施例提供的一种焦平面滤波装置的结构示意图；
图10是本发明实施例提供的又一种焦平面滤波装置的结构示意图。
具体实施方式
下面结合附图和实施例对本发明作进一步的详细说明。可以理解的是，此处所描述的具体实施例仅仅用于解释本发明，而非对本发明的限定。另外还需要说明的是，为了便于描述，附图中仅示出了与本发明相关的部分而非全部结构。
由于光学方法可以非接触地对待测样品进行高分辨无损检测，光学检测方法在测量领域中有十分广泛的应用。而在传统光学检测方法的基础上，通过添加偏振模块，获得偏振光束经样品后的强度信息和偏振属性，以获得样品微观结构信息。
现有技术中，对样品进行偏振特性的检测时，都会假设所检测的偏振光垂直地通过偏振测量系统的光学元件，但是偏振光束透过样品后，会向各个方向发生散射，这使得部分透过样品的偏振光并非垂直于偏振测量系统的光学元件，如此将会引入测量误差，并粗略地舍弃了可能存在于不同散射方向偏振光内的额外信息。同时，在提高偏振测量系统的偏振成像的分辨率时，偏振测量系统所接收的非垂直于光学元件的偏振光的比例增大，多引入的误差就会更明显。
如此，现有技术中在提高偏振成像的分辨率时，会引入较大的偏振测量误差，致使测量信息不准确。
基于上述技术问题，本发明实施例提供一种偏振成像方法，该偏振成像方法能够对透过样品的偏振光进行成像。该偏振成像方法可采用本发明实施例提供的偏振成像装置来执行，该装置可由软件和/或硬件来实现。图1是本发明实施例提供的一种偏振成像方法的流程图。如图1，本发明实施例提供的偏振成像方法包括：
S110、控制经标准样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取标准样品的多个第一偏振属性。
具体的，偏振入射光束透过标准样品的偏振透射光束向各个方向发生散射，且不同方向的偏振透射光束所携带的标准样品的微观结构信息不同。透过样品的偏振透射光束经收集透镜后会聚于收集透镜的焦平面，并由该焦平面上的光阑对会聚于收集透镜的焦平面的偏振透射光束进行空间滤波。由于该光阑的光阑通光孔的位置可以调节，该光阑通光孔的位置调节方式可以为绕光阑的光轴旋转或沿光阑径向方向上发生变化，且不同位置处的光阑通光孔可对不同角度范围和/或不同方向的偏振透射光束进行空间滤波，因此该光阑的光阑通光孔位置不断变化时，就可对透过标准样品的不同角度范围和/或不同方向的偏振透射光束进行空间滤波，从而获得多个不同角度范围和/或不同方向的偏振透射光束，通过检测该多个不同角度范围和/或不同方向的偏振透射光束的偏振属性，即可获得标准样品的多个第一偏振属性。其中， 该标准样品的多个第一偏振属性例如可以包括多个不同方向的偏振透射光束对应的穆勒矩阵。
当入射偏振光束的偏振态以stocks矢量进行表示时，即入射偏振光束的stocks矢量S为：
S＝[I，Q，U，V] T
透过标准样品的偏振透射光束的偏振态用stocks矢量S1表示，M表示透过标准样品前后的偏振光束的穆勒矩阵，如下：
Figure PCTCN2020093460-appb-000001
示例性的，位于收集透镜的焦平面上的光阑具有光阑通光孔，该光阑通光孔的中心与收集透镜的焦点可以重合或不重合。当光阑的结构为圆形时，可调节光阑通光孔的位置沿光阑的径向方向变化，此时光阑能够对不同角度范围的偏振透射光束进行空间滤波。图2是本发明实施例提供的一种光阑通光孔沿光阑的径向方向变化的俯视结构示意图，图3是本发明实施例提供的一种光阑通光孔沿光阑的径向方向变化的侧视结构示意图。结合图2和图3，光阑通光孔的位置可以为第一位置111、第二位置112以及第三位置113的任意一个位置处。其中，光阑通光孔位于第一位置111时，光阑通光孔是半径为r1的圆孔，该圆孔可对第一角度范围的偏振透射光束进行空间滤波，从而获得第一角度范围的偏振透射光束的对应的第一偏振属性；光阑通光孔位于第二位置112时，光阑通光孔为r2-r1的圆环，该圆环可对第二角度范围的偏振透射光束进行空间滤波，从而获得第二角度范围的偏振透射光束的对应的第一偏振属性；光阑通光孔位于第三位置113时，光阑通光孔为r3-r2的圆环，该圆环可对第三角度范围的偏振透射光束进行空间滤波，从而获得第三角度范围的偏振透射光束的对应的第一偏振属性。其中，r1、r2-r1和r3-r2的数值可以相同或不相同。
此外，光阑通光孔的位置还可绕光阑光轴发生变化。图4是本发明实施例提供的一种光阑通光孔与收集透镜的焦点不重合的俯视结构示意图，图5是本发明实施例提供的一种光阑通光孔与收集透镜的焦点不重合的侧视结构示意图。结合图4和图5，光阑通光孔11的中心O'与收集透镜的焦点O不重合，光阑通光孔11绕光阑光轴X1旋转，能够使不同方向的偏振透射光束通过光阑通光孔11。当将光阑10的光阑通光孔11的孔径限制为r2-r1和Ф时，透过光阑通光孔11的偏振透射光束的范围为|α2-α1|。在光阑通光孔11位于初始位置时，透过光阑通光孔11的偏振透射光束的方向为α2～α1；将光阑通光孔11绕光阑光轴X1旋转Ф角度，透过光阑通光孔11的偏振透射光束的方向变为α3～α4。如此，可另光阑通光孔11绕光 阑光轴X1旋转Ф角度的倍数，就可获得不同方向的偏振透射光束。其中，|α2-α1|＝|α4-α3|。如此，通过改变光阑通光孔的位置可获得不同角度范围和/或不同偏振方向的偏振透射光束对应的多个第一偏振属性。
S120、根据所述多个第一偏振属性以及所述标准样品的标准偏振属性获取所述标准样品的多个偏振属性误差。
具体的，标准样品又称实物标准，其与文字标准共同构成标准值。标准样品的标准偏振属性能够反映标准样品的微观结构信息，通过将所测量的标准样品的多个不同角度范围和/或不同方向的偏振透射光束对应的多个第一偏振属性与标准样品的标准偏振属性进行比较，可获得所测量的多个第一偏振属性相对于标准偏振属性的偏离量，即为该标准样品的偏振属性误差。当各第一偏振属性不同时，各第一偏振属性对应的偏振属性误差不同，可将该标准样品的偏振属误差作为偏振成像时的校准误差。其中，标准偏振属性可以为标准样品的标准穆勒矩阵，第一偏振属性可以包括所测量的穆勒矩阵，则所获得的偏振属性误差即为第一偏振属性的穆勒矩阵相对于标准穆勒矩阵的偏离量。
S130、控制经待测样品和收集透镜后的偏振透射光束通过绕光阑光轴旋转的光阑通光孔，以获取待测样品的多个第二偏振属性。
具体的，偏振入射光束透过待测样品的偏振透射光束向各个方向发生散射，且不同方向的偏振透射光束所携带的待测样品的微观结构信息不同。透过待测样品的偏振透射光束经收集透镜后会聚于收集透镜的焦平面，并由该焦平面上的光阑对会聚于收集透镜的焦平面的偏振透射光束进行空间滤波。由于该光阑的光阑通光孔的位置可以调节，该光阑通光孔的位置调节方式可以为绕光阑的光轴旋转或沿光阑径向方向上发生变化，且不同位置处的光阑通光孔可对不同角度范围和/或不同方向的，因此该光阑的光阑通光孔位置不断变化时，就可对透过待测样品的不同角度范围和/或不同方向的偏振透射光束进行空间滤波，从而获得多个不同角度范围和/或不同方向的偏振透射光束，通过检测该多个不同角度范围和/或不同方向的偏振透射光束的偏振属性，即可获得待测样品的多个第一偏振属性。其中，该待测样品的多个第二偏振属性例如可以包括多个不同方向的偏振透射光束对应的穆勒矩阵。透过待测样品的偏振透射光束的偏振态用stocks矢量S2表示，M'表示透过待测样品的偏振光的穆勒矩阵，如下：
Figure PCTCN2020093460-appb-000002
其中，待测样品的多个第二偏振属性的获取方式与标准样品的多个第一偏振属性的获取方式相同。
需要说明的是，图2、图3、图4和图5仅为本发明实施例示例性的光阑结构示意图，在能够控制光阑通光孔对不同角度范围和/或不同方向的偏振透射光束进行空间滤波的前提下，对光阑和光阑通光孔的结构、以及光阑通光孔的位置变化形式不做具体限定。其中，以图2和图3为例，在光阑通光孔位于第一位置11时，光阑通光孔111的中心与收集透镜的焦点O重合，该位于第一位置111的光阑通光孔的尺寸r1可限定在一个很小的范围，可认为透过光阑10的光阑通光孔11的偏振透射光束为垂直于收集透镜的焦平面S的偏振透射光束；或者，依据实际情况对第一位置111的光阑通光孔的尺寸r1进行限定，并对应获取标准样品的第一偏振属性和待测样品的第二偏振属性。
S140、根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像。
具体的，由于偏振成像系统的分辨率越高，其偏振成像的清晰度和对比度越高，辨识度越高，因此在偏振成像时提高偏振成像系统的分辨率至关重要。通常，偏振成像系统中设置有收集透镜，以收集偏振入射光束通过待测样品后的偏振透射光束，该收集透镜的数值孔径NA越大，收集透镜的吸光能力越强，所收集的偏振透射光束成像后的分辨率越高。根据定义，收集透镜的数值孔径由收集透镜与待测样品之间介质的折射率n和孔径角2α的半数决定，即数值孔径NA为：
Figure PCTCN2020093460-appb-000003
其中，D为收集透镜的直径，f为收集透镜的焦距。在不考虑收集透镜与待测样品之间的介质折射率n的情况下，在提高收集透镜的收光能力时，需要增大收集透镜的直径D或减小收集透镜的焦距f。当收集透镜与待测样品之间的介质为空气时，根据分辨率d在空气中的定义：
Figure PCTCN2020093460-appb-000004
其中，λ为偏振光束的波长。在不考虑波长λ的情况下，提高偏振成像系统的分辨率，则就需要增大收集透镜的数值孔径NA。而在增大收集透镜的数值孔径增大时，采用增大收集透镜的直径D或减小收集透镜的焦距f的方式，必会使更多的非垂直于偏振成像系统的光学元件的偏振透射光束。如此，将会进一步增大偏振成像的误差，降低测量信息的准确度。通过在测量待测样品的多个第二偏振属性后，调用根据标准样品的多个第一偏振属性和标准 偏振属性获得的多个偏振属性误差，并由多个偏振属性误差和多个第二偏振属性，获得待测样品的偏振图像。其中，当偏振属性误差为不同角度范围的偏振透射光束对应的误差时，即可对不同角度范围的偏振透射光束对应的第二偏振属性进行校准，从而在通过校准后的多个第二偏振属性获得待测样品的偏振图像时，可相当于增加收集透镜的数值孔径NA，并将数值孔径NA增加后所引入的误差通过偏振属性误差进行抵消，从而能够在提高偏振成像分辨率的前提下，降低偏振成像误差；当偏振属性误差为不同方向的偏振透射光束对应的误差时，即可对不同方向的偏振透射光束对应的第二偏振属性进行校准，从而在通过校准后的多个第二偏振属性获得待测样品的偏振图像时，可获得待测样品的各向异性信息，从而能够丰富所获得待测样品的结构信息，进一步增加待测样品的偏振成像的准确度。
本发明实施例通过变化光阑通光孔的位置，以使经收集透镜后的不同角度范围和/或不同方向的偏振透射光束透过光阑的光阑通光孔，以获得标准样品的多个第一偏振属性和待测样品的多个第二偏振属性，并由标准样品的多个第一偏振属性与标准样品的标准属性得到多个偏振属性误差，从而能够在获得待测样品的不同角度的多个第二偏振属性后，由偏振属性误差对不同角度的多个第二偏振属性进行校准，以在降低所获得的多个第二偏振属性的偏振属性误差的前提下，提高待测样品偏振图像的分辨率，获得待测样品的各向异性信息，并且偏振成像方法简单，成本低。
可选的，在上述实施例的基础上，根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像的方法具体包括：根据所述多个偏振属性误差对应校准所述多个第二偏振属性，获取多个校准偏振属性；根据所述多个校准偏振属性，获取多个校准偏振图像；合并所述多个校准偏振图像，以获取所述待测样品的偏振图像。图6是本发明实施例提供的偏振图像合成方法的流程图。如图6，该方法包括：
S141、根据所述多个偏振属性误差对应校准所述多个第二偏振属性，获取多个校准偏振属性；
S142、根据所述多个校准偏振属性，获取多个校准偏振图像；
S143、合并所述多个校准偏振图像，以获取所述待测样品的偏振图像。
具体的，通过接收待测样品的多个不同方向的偏振透射光束，即可对应获得待测样品的多个第二偏振属性。由于待测样品的多个第二偏振属性对应的偏振透射光束的角度范围和/或方向与标准样品的多个第一偏振属性的对应的偏振透射光束的角度范围和/或方向相同，因此可根据标准样品的多个第一偏振属性和标准偏振属性对应获得的多个偏振属性误差对应校准多个第二偏振属性，获得该待测样品的多个第二偏振属性校准后的多个校准偏振属性。 每一校准偏振属性都可获得一个待测样品的偏振图像，即校准偏振图像。通过将多个校准偏振属性获得的多个校准偏振图像合并成一个偏振图像，所合并的偏振图像即为待测样品的偏振图像。
如此，第一方面，通过多个不同角度范围的偏振透射光束获得的多个第二偏振属性，可获得高分辨率的偏振图像；第二方面，通过对多个第二偏振属性进行校准，所获得的高分辨率的偏振图像具有较小的误差，较高的准确度；第三方面，通过多个不同方向的偏振透射光束获得的多个第二偏振属性，可获得待测样品的各向异性信息。
本发明实施例还提供了一种偏振成像装置，该偏振成像装置可执行本发明实施例提供的偏振成像方法，该装置可由软件和/或硬件来实现。图7是本发明实施例提供的一种偏振成像装置的结构框图。如图7，本发明实施例的偏振成像装置包括：第一偏振属性获取单元101、偏振属性误差获取单元102、第二偏振属性获取单元103和偏振图像获取单元104。
所述第一偏振属性获取单元101，用于控制经标准样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取标准样品的多个第一偏振属性；
所述偏振属性误差获取单元102，用于根据所述多个第一偏振属性以及所述标准样品的标准偏振属性获取所述标准样品的多个偏振属性误差；
所述第二偏振属性获取单元103，用于控制经待测样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取待测样品的多个第二偏振属性；
所述偏振图像获取单元104，用于根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像。
本发明实施例通过变化光阑通光孔的位置，以使经收集透镜后的不同角度范围和/或不同方向的偏振透射光束透过光阑的光阑通光孔，以获得标准样品的多个第一偏振属性和待测样品的多个第二偏振属性，并由标准样品的多个第一偏振属性与标准样品的标准属性得到多个偏振属性误差，从而能够在获得待测样品的不同角度的多个第二偏振属性后，由偏振属性误差对不同角度的多个第二偏振属性进行校准，以在降低所获得的多个第二偏振属性的偏振属性误差的前提下，提高待测样品偏振图像的分辨率，获得待测样品的各向异性信息，并且偏振成像方法简单，成本低。
本发明实施例提供的偏振成像装置，可执行本发明任意实施例所提供的偏振成像方法，具备执行该方法相应的功能模块和有益效果。未在上述实施例中详尽描述的技术细节，可参见本发明任意实施例所提供的偏振成像方法。
本发明实施例还提供了一种偏振成像系统，能够实现本发明实施例提供的偏振成像方法。 图8是本发明实施例提供的一种偏振成像系统的结构示意图。如图8，该偏振成像系统包括焦平面滤波装置100和本发明实施例提供的偏振成像装置200；其中，焦平面滤波装置100包括沿光路依次设置的光束出射单元20、收集透镜30、光阑10和光束接收单元40；待测样品50或标准样品60放置于光束出射单元20和收集透镜30之间；光束出射单元20用于提供偏振入射光束，并投射至待测样品50或标准样品60上；收集透镜30用于将透过待测样品50或所述标准样品60的偏振透射光会聚于收集透镜30的焦平面S上；光阑10位于收集透镜30的焦平面S上，光阑10用于控制会聚于焦平面S上的预设角度的偏振透射光透过焦平面S；光阑10包括光阑通光孔；光束接收单元40用于接收透过焦平面S的偏振透射光。
具体的，光束出射单元20提供的偏振入射光束透过待测样品50或标准样品60的偏振透射光束经收集透镜30会聚于收集透镜30的焦平面S；设置于该焦平面S上的光阑10对会聚于收集透镜30的焦平面S的偏振透射光束进行空间滤波，以使预设角度的偏振透射光透过焦平面S；光束接收单元40接收透过焦平面S的预设角度的偏振透射光束，并将该预设角度的偏振透射光束发送至偏振成像装置200中，该偏振成像装置200能够根据预设角度的偏振透射光束获得对应的待测样品50的第二偏振属性或标准样品60的第一偏振属性。同时，通过调节光阑10的光阑通光孔的位置，该光阑10的光阑通光孔的位置调节方式可以为绕光阑10的光轴旋转或沿光阑10的径向方向上发生变化，且不同位置处的光阑通光孔可对不同角度范围和/或不同方向的预设角度的偏振透射光束进行空间滤波，从而获得不同角度范围和/或不同方向的偏振透射光束。通过检测该多个不同角度范围和/或不同方向的偏振透射光束的偏振属性，即可获得待测样品50的多个第二偏振属性或标准样品60的多个第一偏振属性。
其中，可选的光阑10的光阑通光孔的中心与收集透镜30的焦点O不重合。如此，能够在控制光阑10的光阑通光孔绕光阑10的光轴旋转时，获得多个不同方向的偏振透射光束。该多个第二偏振属性、多个第一偏振属性例如均可以包括多个不同角度范围和/或不同方向的偏振透射光束对应的穆勒矩阵。
通过标准样品60的多个第一偏振属性和标准偏振属性，即可获得偏振成像系统在偏振成像时的多个偏振属性误差，通过对所获得的待测样品50的多个第二偏振属性进行相应的偏振属性误差的校准，即可获得较准确的多个校准偏振属性，由该多个校准偏振属性可获得多个校准偏振图像，通过合并各校准偏振图像，即可获得待测样品50的偏振图像，从而获得待测样品50的微观结构。
本实施例通过在收集透镜的焦平面设置光阑，以使透过待测样品或标准样品的偏振透射光中预设角度的偏振透射光透过收集透镜的焦平面，从而通过改变光阑的光阑通光孔的位置， 即可获得多个不同角度范围和/或不同方向的偏振透射光对应的偏振属性。一方面，通过标准样品的偏振属性误差对待测样品的偏振属性进行校准，能够使待测样品的偏振图像具有较高的准确度；另一方面，通过多个不同角度范围和/或不同偏振方向的偏振透射光的所合成的待测样品的偏振图像具有较高的分别率，并且能够获得待测样品的各向异性信息。
可选的，图9是本发明实施例提供的一种焦平面滤波装置的结构示意图。如图9，在上述实施例的基础上，焦平面滤波装置100还包括：检偏单元70；检偏单元70位于光束出射单元20与光束接收单元40之间的光路中；待测样品50或标准样品60放置于光束出射单元20和检偏单元70之间；检偏单元70用于调整透过待测样品50或标准样品60的偏振透射光束的偏振状态。
其中，检偏单元70可选的包括沿光路依次设置的第一波片71和第一偏振片72；第一波片71与第一偏振片72相对设置，透过待测样品50或标准样品60的偏振透射光束依次经第一波片71和第一偏振片72传播。
需要说明的是，检偏单元70位于光束出射单元20与光束接收单元40之间的光路中，该检偏单元70可以位于光束出射单元20与收集透镜30之间的光路中；或者，该检偏单元70还可以位于收集透镜30与光阑10之间的光路中；或者，该检偏单元70还可以位于光阑10与接收单元之间的光路中。图9示例性的以检偏单元70位于收集透镜30与光阑10之间的光路中为例进行说明。在检偏单元70位于其它位置时的技术原理与图9所示的技术原理类似，在此不再赘述。
具体的，光束出射单元20提供的偏振入射光束透过待测样品50或标准样品60，该透过待测样品50或标准样品60的偏振透射光在通过检偏单元70时会进行偏振状态的调整。通过旋转检偏单元70的第一波片71，即可改变透过该检偏单元70的偏振透射光的偏振状态。其中，第一波片71可选为1/4波片。
可选的，图10是本发明实施例提供的又一种焦平面滤波装置的结构示意图。如图10，焦平面滤波装置100的光束出射单元20包括沿光路依次设置的光源21和偏振子单元22；光源21用于提供特定波长的平行光；偏振子单元22包括相对设置的第二偏振片221和第二波片222；自然光依次经过第二偏振片221和第二波片222转换为偏振入射光束，投射至待测样品50或标准样品60。
具体的，光束出射单元20提供的偏振入射光束具有一定的偏振方向，通光控制第二波片222相对于第二偏振片221的偏振方向，即可获得不同偏振方向的偏振入射光束。其中，第二波片222可选为1/4波片。该第二波片222可与第一波片71结合，可分别测得不同偏振 方向的偏振透射光。
本发明实施例提供的偏振成像方法及其装置、偏振成像系统，通过变化光阑通光的位置，以使经收集透镜后的不同角度范围和/或不同方向的偏振透射光束透过光阑的光阑通光孔，以获得标准样品的多个第一偏振属性和待测样品的多个第二偏振属性，并由标准样品的多个第一偏振属性与标准样品的标准属性得到多个偏振属性误差，从而能够在获得待测样品的不同角度的多个第二偏振属性后，由偏振属性误差对不同角度的多个第二偏振属性进行校准，以在降低所获得的多个第二偏振属性的偏振属性误差的前提下，提高待测样品偏振图像的分辨率，获得待测样品的各向异性信息，并且偏振成像方法简单，成本低。
注意，上述仅为本发明的较佳实施例及所运用技术原理。本领域技术人员会理解，本发明不限于这里所述的特定实施例，对本领域技术人员来说能够进行各种明显的变化、重新调整、相互结合和替代而不会脱离本发明的保护范围。因此，虽然通过以上实施例对本发明进行了较为详细的说明，但是本发明不仅仅限于以上实施例，在不脱离本发明构思的情况下，还可以包括更多其他等效实施例，而本发明的范围由所附的权利要求范围决定。

Claims (10)

  1. 一种偏振成像方法，其特征在于，包括：
    控制经标准样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取标准样品的多个第一偏振属性；
    根据所述多个第一偏振属性以及所述标准样品的标准偏振属性获取所述标准样品的多个偏振属性误差；
    控制经待测样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取待测样品的多个第二偏振属性；
    根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像。
  2. 根据权利要求1所述的方法，其特征在于，所述根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像包括：
    根据所述多个偏振属性误差对应校准所述多个第二偏振属性，获取多个校准偏振属性；
    根据所述多个校准偏振属性，获取多个校准偏振图像；
    合并所述多个校准偏振图像，以获取所述待测样品的偏振图像。
  3. 根据权利要求1～2任一项所述方法，其特征在于，所述第一偏振属性、所述第二偏振属性均包括穆勒矩阵。
  4. 一种偏振成像装置，其特征在于，包括：
    第一偏振属性获取单元，用于控制经标准样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取标准样品的多个第一偏振属性；
    偏振属性误差获取单元，用于根据所述多个第一偏振属性以及所述标准样品的标准偏振属性获取所述标准样品的多个偏振属性误差；
    第二偏振属性获取单元，用于控制经待测样品和收集透镜后的偏振透射光束通过位置变化的光阑通光孔，以获取待测样品的多个第二偏振属性；
    偏振图像获取单元，用于根据所述多个第二偏振属性以及所述多个偏振属性误差获取所述待测样品的偏振图像。
  5. 一种偏振成像系统，其特征在于，包括：焦平面滤波装置和权利要求7所述的偏振成像装置；
    所述焦平面滤波装置包括沿光路依次设置的光束出射单元、收集透镜、光阑和光束接收单元；待测样品或标准样品放置于所述光束出射单元和所述收集透镜之间；
    所述光束出射单元用于提供偏振入射光束，并投射至待测样品或标准样品上；
    所述收集透镜用于将透过所述待测样品或所述标准样品的偏振透射光束会聚于所述收 集透镜的焦平面上；
    所述光阑位于所述收集透镜的焦平面上，所述光阑用于控制会聚于所述焦平面上的预设角度的所述偏振透射光束透过所述焦平面；所述光阑包括光阑通光孔；
    所述光束接收单元用于接收透过所述焦平面的所述偏振透射光束。
  6. 根据权利要求5所述的系统，其特征在于，所述焦平面滤波装置还包括：检偏单元；
    所述检偏单元位于所述光束出射单元与所述光束接收单元之间的光路中；所述待测样品或所述标准样品放置于所述光束出射单元和所述检偏单元之间；所述检偏单元用于调制透过所述待测样品或所述标准样品的偏振透射光束的偏振状态。
  7. 根据权利要求6所述的系统，其特征在于，所述检偏单元包括沿光路依次设置的第一波片和第一偏振片；
    所述第一波片与所述第一偏振片相对设置，透过所述待测样品或所述标准样品的偏振透射光束依次经所述第一波片和第一偏振片传播。
  8. 根据权利要求7所述的系统，其特征在于，所述光束出射单元包括沿所述光路依次设置的光源、偏振子单元；
    所述光源用于提供特定波长的平行光；
    所述偏振子单元包括相对设置的第二偏振片和第二波片；所述自然光依次经过所述第二偏振片和第二波片转换为偏振入射光束，投射至所述待测样品或所述标准样品。
  9. 根据权利要求8所述的系统，其特征在于，所述第一波片与所述第二波片均为1/4波片。
  10. 根据权利要求5～9任一项所述的系统，其特征在于，所述光阑通光孔的中心与所述收集透镜的焦点不重合。
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