CN110514598B - Spectral polarization detection system and detection method for frequency domain modulation - Google Patents
Spectral polarization detection system and detection method for frequency domain modulation Download PDFInfo
- Publication number
- CN110514598B CN110514598B CN201910766902.9A CN201910766902A CN110514598B CN 110514598 B CN110514598 B CN 110514598B CN 201910766902 A CN201910766902 A CN 201910766902A CN 110514598 B CN110514598 B CN 110514598B
- Authority
- CN
- China
- Prior art keywords
- polarization state
- column vector
- polarization
- sample
- detector
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 230000010287 polarization Effects 0.000 title claims abstract description 108
- 238000001514 detection method Methods 0.000 title claims abstract description 31
- 230000003595 spectral effect Effects 0.000 title claims abstract description 25
- 239000013078 crystal Substances 0.000 claims abstract description 54
- 238000012545 processing Methods 0.000 claims abstract description 22
- 239000013598 vector Substances 0.000 claims description 78
- 238000010183 spectrum analysis Methods 0.000 claims description 44
- 239000011159 matrix material Substances 0.000 claims description 43
- 238000003384 imaging method Methods 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 13
- 230000009466 transformation Effects 0.000 claims description 11
- 238000005070 sampling Methods 0.000 claims description 10
- 238000004458 analytical method Methods 0.000 claims description 9
- 230000009471 action Effects 0.000 claims description 8
- 238000005457 optimization Methods 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 7
- 230000000694 effects Effects 0.000 claims description 5
- 238000005259 measurement Methods 0.000 abstract description 14
- 238000004364 calculation method Methods 0.000 abstract description 5
- 230000008901 benefit Effects 0.000 abstract description 3
- 238000011084 recovery Methods 0.000 abstract description 3
- 230000005540 biological transmission Effects 0.000 description 16
- QWVYNEUUYROOSZ-UHFFFAOYSA-N trioxido(oxo)vanadium;yttrium(3+) Chemical compound [Y+3].[O-][V]([O-])([O-])=O QWVYNEUUYROOSZ-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 239000013307 optical fiber Substances 0.000 description 4
- 229910021532 Calcite Inorganic materials 0.000 description 3
- 238000003745 diagnosis Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 238000011426 transformation method Methods 0.000 description 3
- 230000001131 transforming effect Effects 0.000 description 3
- 206010028980 Neoplasm Diseases 0.000 description 2
- 201000011510 cancer Diseases 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 230000036039 immunity Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000003672 processing method Methods 0.000 description 2
- 241000227425 Pieris rapae crucivora Species 0.000 description 1
- 208000025865 Ulcer Diseases 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 210000003238 esophagus Anatomy 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 210000001035 gastrointestinal tract Anatomy 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 210000000936 intestine Anatomy 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000028161 membrane depolarization Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 210000004877 mucosa Anatomy 0.000 description 1
- 210000000056 organ Anatomy 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 210000002784 stomach Anatomy 0.000 description 1
- 210000001519 tissue Anatomy 0.000 description 1
- 231100000397 ulcer Toxicity 0.000 description 1
Images
Classifications
-
- 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
- G01J3/02—Details
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
-
- 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
- G01J3/12—Generating the spectrum; Monochromators
-
- 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
- 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
Abstract
The invention discloses a spectral polarization detection system and a detection method of frequency domain modulation, belonging to the technical field of polarization measurement, wherein a polarization state generator and a polarization state analyzer in the system are composed of a fixed birefringent crystal and a linear polarizer, and do not need any electromechanical measurement and control device, thereby reducing the volume and weight of the system and having the advantages of flexibility, compactness, low cost, stable performance and the like; the data processing module in the system projects the spectral polarization data to be recovered to a low-dimensional space, so that the calculation resource overhead and time are reduced, the anti-noise performance is enhanced by utilizing the regular term during data recovery, and the measurement time of the system and the polarization measurement precision under the low signal-to-noise ratio are improved.
Description
Technical Field
The invention belongs to the technical field of polarization measurement, and particularly relates to a spectral polarization detection system and a spectral polarization detection method for frequency domain modulation.
Background
Polarization is an important property of light, and polarized light is very sensitive to microstructure characteristics in samples such as optical elements, materials, biological tissues and the like. The interaction of light with the sample can cause refraction, reflection, scattering, etc. to change the polarization state of the incident light. The change capability of the sample on the polarization state of light is represented by a Mueller matrix, the Mueller matrix contains all polarization information of the sample, can be further decomposed into polarization parameters which are closely related to the microstructure of the sample, have practical physical significance, can be quantized, such as depolarization, phase retardation, dichroism, fast axis direction angle, optical rotation and the like, and can be used for obtaining the polarization characteristics and the structural parameters of the sample. A great deal of research shows the application effect of the polarimeter in the aspects of objective polarization aberration detection, multilayer film thickness analysis, microstructure device parameter detection, cancer diagnosis and curative effect monitoring. However, the polarization information cannot be directly detected, and must be obtained by demodulation after being modulated to other domains, and the modulation and demodulation determine the structural form, the measurement speed and the measurement precision of the system, so the modulation mode and the data processing method of the polarimeter are extremely important.
Taking cancer diagnosis as an example, a common white light endoscope can clearly display the conditions of the cavity mucosa and discover abnormal conditions such as nodules and ulcers, but the imaging depth is limited to the surface. In order to improve the imaging contrast and the diagnosis accuracy, a polarization endoscopic imaging technology is proposed. Patent document CN104161493A discloses a polarization imaging endoscope system and an endoscopic imaging method, which are based on a rigid endoscope design, are difficult to enter into the digestive tract organs such as esophagus, intestines and stomach, and have limited use scenes. The patent document CN106725250A discloses a flexible endoscopic polarization imaging system and a measurement method with time modulation at the distal end, wherein the rotating motor at the distal end of the endoscope occupies the instrument channel and the flushing channel, so that the distal head is too large, and the time modulation mode may take much measurement time. The documents Rivet S, Bradu A, Podolean A.70kHz full 4x4Mueller polarimeter and simulaneous fiber alignment [ J ]. Optics express,2015,23(18) disclose a proximal frequency domain modulation polarization flexible endoscope, which places a polarization modulation device at the proximal end of the endoscope, adopts an optical fiber for image transmission, belongs to a non-imaging endoscope, and therefore a two-dimensional scanning mechanism is required to be added at the distal end of the endoscope, and the field of view is limited; the optical fibers in the endoscope can generate birefringence due to the characteristics of the optical fibers or stress, and measurement errors are introduced.
The above systems relate to the modulation process of a polarizer, and for the demodulation process of a data processing method (demodulation process), documents L aCasse C F, Chipman R A, Tyo J S.band limited data recovery modulated polarizers [ J ]. Optics express,2011,19(16): 14976:14989summarize the most widely used Fourier method and linear transformation method at present, wherein the Fourier method has the problems of band crosstalk, high frequency loss, poor anti-noise performance and the like, and the linear transformation method also has poor anti-noise performance and affects the precision of the data processing of the modulation polarizer.
Disclosure of Invention
In view of this, the invention provides a spectral polarization detection system and a detection method using frequency domain modulation, which can solve the problems of frequency band crosstalk, high frequency loss and poor noise immunity existing in the fourier method; the problem of poor noise immunity existing in a linear transformation method is solved, and the detection precision of a frequency domain modulation polarization measurement system is improved.
The technical scheme for realizing the invention is as follows:
a spectral polarization detection system of frequency domain modulation comprises a polarization state analyzer, a detector and a data processing module;
the polarization state analyzer consists of a fixed birefringent crystal and a fixed linear polarizer;
the light beam to be detected sequentially penetrates through the birefringent crystal and the linear polaroid and is received by the detector, and the detector performs spectral analysis on the received light beam and sends an analysis result to the data processing module;
the data processing module rewrites the Stokes vector initially set by the light beam to be measured into a column vector X, and the transformation action of the polarization state analyzer on the column vector X is expressed by phi; calculating coefficients of the column vector X under the expression that the matrix psi is base
By varying said coefficients with constant phi
Obtaining simulated spectral analysis results under different Stokes vector input conditions to
Represents; in the coefficient
Is used as the regular term constraint, the coefficient is optimized by iteration
The simulated spectral analysis result
Obtaining a corresponding system closest to the spectral analysis result of the detectorNumber of
Value of (A)
Finally utilize
And obtaining the Stokes vector of the light beam to be detected.
A spectral polarization detection system of frequency domain modulation comprises a polarization state analyzer, a polarization state generator, a detector and a data processing module;
the polarization state generator and the polarization state analyzer are both composed of a fixed linear polarizer and a fixed birefringent crystal;
the light beams sequentially penetrate through the linear polarizer and the birefringent crystal of the polarization state generator and then irradiate the sample to be detected, the light beams from the sample to be detected sequentially penetrate through the birefringent crystal and the linear polarizer of the polarization state analyzer and are received by the detector, and the detector performs spectral analysis on the received light beams and sends the analysis result to the data processing module;
the data processing module rewrites a Mueller matrix initially set by a sample to be tested into a column vector X ', and the transformation action of the polarization state generator and the polarization state analyzer on the column vector X ' is represented by phi '; calculating coefficients of the column vector X' in a representation based on the matrix Ψ
By varying said coefficients with phi' unchanged
Obtaining simulated spectral analysis results under different Mueller matrix input conditions to obtain
Represents; in the coefficient
Is used as the regular term constraint, the coefficient is optimized by iteration
The simulated spectral analysis result
Obtaining a coefficient closest to and corresponding to the spectral analysis result of the detector
Value of (A)
Finally utilize
And obtaining a Mueller matrix of the sample to be detected.
Further, the system also comprises a collimating lens, a condenser lens, an objective lens and an image-forming lens;
the polarization state generator and the polarization state analyzer are both positioned at the far end of the system, namely close to a sample to be detected;
the polarization state generator is positioned in a parallel light path between the collimating mirror and the collecting mirror;
the polarization state analyzer is positioned in a parallel light path between the objective lens and the image forming lens;
after being coupled to a collimating mirror in a rigid or flexible mode, a light beam sequentially passes through a polarization state generator and a condenser mirror and then irradiates a sample to be measured; light beams from a sample to be detected pass through the objective lens and the polarization state analyzer and are focused on the detector by the image condenser, the detector performs spectral analysis on the received light beams, and an analysis result is sent to the data processing module.
A spectral polarization detection method of frequency domain modulation comprises the following steps:
step one, rewriting a Stokes vector S initially set by a light beam to be detected into a column vector X, and expressing the transformation action of the system on the column vector X by phi;
in the second step, the first step is that,calculating coefficients of a column vector X in a representation based on a matrix Ψ
Namely, it is
Wherein the content of the first and second substances,
represents the pseudo-inverse, then
By changing X, i.e. the coefficient, with phi constant
The simulated spectral analysis results under different Stokes vector inputs are obtained as phi X, i.e.
Step three, rewriting the spectral analysis result output by the detector of the system into a column vector Y, and performing iterative optimization
Obtaining the coefficient
Wherein | | | purple hairpRepresents a p-norm; by passing
And obtaining a column vector X, and further obtaining a Stokes vector of the light beam to be detected.
Further, in step one, the initial value of the Stokes vector S is composed of
And (4) calculating.
Further, in step two, the coefficients
Is initially calculated by
Calculating to obtain; Ψ is an orthogonal basis constituted by Legendre polynomials,
Ψ＝diag(P…P)
Pn(xi) Is a legendre polynomial, N is 1,2,., L, i is 1, 2., N,
wherein x isiIn [ -1,1 [)]And uniformly sampling.
Further, in step three, p is 1.
A spectral polarization detection method of frequency domain modulation comprises the following steps:
step one, rewriting a Mueller matrix M initially set by a sample to be detected into a column vector X ', and expressing the transformation effect of the system on the column vector X ' by phi ';
step two, calculating coefficients of the column vector X 'under psi' as base expression
Namely, it is
Wherein the content of the first and second substances,
represents the pseudo-inverse, then
By changing X ', i.e. changing the coefficient, with phi' unchanged
The simulated spectral analysis results under different Mueller matrix inputs are obtained as phi '. X', that is
Step three, rewriting the spectral analysis result output by the detector of the system into a column vector Y', and performing iterative optimization
Obtaining the coefficient
Wherein | | | purple hairpRepresents a p-norm; by passing
And obtaining a column vector X' so as to obtain a Mueller matrix of the sample to be detected.
Further, in step one, the initial value of the Mueller matrix M is determined by
And (4) calculating.
Further, in step two, the coefficients
Is initially calculated by
Calculating to obtain; Ψ' is an orthogonal basis composed of Legendre polynomials,
Ψ′＝diag(P′…P′)
Pn′(xi) Is a legendre polynomial, N is 1,2,., L, i is 1, 2., N,
wherein x isiIn [ -1,1 [)]And uniformly sampling.
Further, in step three, p is 1.
Has the advantages that:
1. the spectrum polarization detection system and the detection method project the spectrum polarization data to be recovered to a low-dimensional space, reduce the calculation resource cost and time, enhance the anti-noise performance by utilizing the regular term during data recovery, improve the problems of frequency band crosstalk and high frequency loss in a Fourier method, and improve the system measurement speed and the polarization measurement precision under the low signal-to-noise ratio.
2. The polarization state generator and the polarization state analyzer in the spectral polarization imaging system are composed of the fixed birefringent crystal and the linear polarizer, any electromechanical measurement and control device is not needed, the volume and the weight of the system are reduced, and the spectral polarization imaging system has the advantages of flexibility, compactness, low cost, stable performance and the like.
3. The polarization state generator and the polarization state analyzer in the spectral polarization imaging system are respectively integrated with the illumination module and the imaging module at the far end of the system, other light guide media are not needed, and polarization measurement errors introduced in the light transmission process are reduced.
Drawings
FIG. 1 is a schematic diagram of a spectral polarization detection system.
Fig. 2 is a flowchart of a spectral polarization detection method using frequency domain modulation.
101-a light source, 102-a light guide pipe, 103-a collimating mirror, 104-a collecting mirror, 201-a linear polarizer, 202-a birefringent crystal, 203-a birefringent crystal, 301-a birefringent crystal, 302-a birefringent crystal, 303-a linear polarizer, 401-an objective lens, 402-an imaging mirror, 403-a fiber bundle, 404-a detector, 501-a data processing module, 601-an illumination channel, 602-an imaging channel and 701-a sample.
Detailed Description
The invention is described in detail below by way of example with reference to the accompanying drawings.
The invention provides a spectral polarization detection system modulated in a frequency domain, which comprises the following three types of embodiments as shown in figure 1:
stokes vector detection system of light beam
The light source 101 is artificial light or natural light with a certain bandwidth, the light beam generated by the light source 101 irradiates on the sample 701, the sample 701 may be a transmission sample (including vacuum and air), and a reflection sample, for the transmission sample, the light source and the polarization state analyzer are located at two sides of the sample, for the reflection sample, the light source and the polarization state analyzer are located at the same side of the sample, the light beam to be measured from the sample sequentially penetrates through the birefringent crystal 301, the birefringent crystal 302, and the linear polarizer 303 in the polarization state analyzer, and is received by the detector 404, and the detector 404 performs spectral analysis on the received light beam, and sends the analysis result to the data processing module 501.
In a preferred configuration, the fast axis of the birefringent crystal 301 is in the same direction as the transmission axis of the linear polarizer 303, the fast axis of the birefringent crystal 302 is at 45 degrees to the transmission axis of the linear polarizer 303, the thickness ratio of the birefringent crystal 301 to the birefringent crystal 302 is 1:2, the materials of the birefringent crystals 301 and 302 can be quartz crystal, calcite crystal, yttrium vanadate crystal, etc., and a preferred material of the birefringent crystal is yttrium vanadate crystal, which has higher birefringence and smaller thickness, and can further reduce the system volume.
The data processing module 501 rewrites the Stokes vector initially set by the light beam to be measured into a column vector X, and represents the transformation action of the polarization analyzer on the column vector X by phi; calculating coefficients of the column vector X under the expression that the matrix psi is base
By varying said coefficients with constant phi
Obtaining simulated spectral analysis results under different Stokes vector input conditions to
Represents; in the coefficient
Is used as a regular term constraint, and the coefficient is optimized through iteration
The simulated spectral analysis result
Obtaining a coefficient closest to and corresponding to the spectral analysis result of the detector
Value of (A)
Finally utilize
And obtaining the Stokes vector of the light beam to be detected. As shown in fig. 2, the specific steps are as follows:
step one, a Stokes vector of a light beam to be detected is initially set
Rewriting to column vectors
Wherein, v represents the frequency domain,
representing the Stokes vector is a real matrix of 4 × 1, the system has N sampling points in the frequency domain, each element in the Stokes vector initially set by the light beam to be measured is unknown number or random number, and the polarization state analyzer is used for transforming the column vector X
And (4) showing.
Step two, calculating coefficients of the column vector X under psi base representation
Namely, it is
Wherein the content of the first and second substances,
represents the pseudo-inverse, then
The result of the simulated spectral analysis obtained by calculation is phi X, i.e.
Wherein Ψ is an orthogonal basis constituted by Legendre polynomials,
i＝1,2,...,N，
Step three, rewriting the spectral analysis result of the detector in the system into a column vector
Iterative optimization
Obtaining the coefficient
Wherein | | | purple hairpRepresents the p normCoefficient of
Is initially calculated by
Calculating to obtain; by
And obtaining a column vector X, and further obtaining a Stokes vector of the light beam to be detected.
Mueller matrix detection system of (II) sample
The light source 101 is artificial light or natural light with a certain bandwidth, light beams generated by the light source 101 are modulated by the linear polarizer 201, the birefringent crystal 202 and the birefringent crystal 203 in the polarization state generator and then irradiate the sample 701 to be measured, the sample 701 to be measured can be a transmission sample to be measured and a reflection sample to be measured, for the transmission sample to be measured, the light source and the polarization state analyzer are located on two sides of the sample to be measured, for the reflection sample to be measured, the light source and the polarization state analyzer are located on the same side of the sample to be measured, the light beams from the sample to be measured sequentially penetrate through the birefringent crystal 301, the birefringent crystal 302 and the linear polarizer 303 in the polarization state analyzer and are received by the detector 404, the detector 404 performs spectral analysis on the received light beams, and sends.
In a preferred configuration, the transmission axis directions of the linear polarizer 201 and the linear polarizer 303 are the same, the fast axis direction of the birefringent crystal 202, 302 and the transmission axis direction of the linear polarizer 201, 303 form an angle of 45 degrees, the fast axis direction of the birefringent crystal 203, 301 and the transmission axis direction of the linear polarizer 201, 303 are the same, the thickness ratio of the birefringent crystal 202, 203, 301, 302 is 1:2:5:10, the birefringent crystal 301, 302 can be quartz crystal, calcite crystal, yttrium vanadate crystal, etc., a preferred birefringent crystal material is yttrium vanadate crystal, which has higher birefringence and smaller thickness, and can further reduce the system volume.
The data processing module 501 rewrites the Mueller matrix initially set for the sample to be tested into a column vector X', and the polarization state generator and the polarization state are usedThe transformation effect of the analyzer on the column vector X 'is represented by phi'; calculating coefficients of the column vector X' in a representation based on the matrix Ψ
By varying said coefficients with phi' unchanged
Obtaining simulated spectral analysis results under different Mueller matrix input conditions to obtain
Represents; in the coefficient
Is used as a regular term constraint, and the coefficient is optimized through iteration
The simulated spectral analysis result
Obtaining a coefficient closest to and corresponding to the spectral analysis result of the detector
Value of (A)
Finally utilize
And calculating to obtain a Mueller matrix of the sample to be detected. The method comprises the following specific steps:
step one, a Mueller matrix of a sample to be detected is initially set
Rewriting to column vectors
Wherein, v represents the frequency domain,
indicating that the Mueller matrix is a real matrix of 4 × 4, wherein the system has N sampling points in the modulation domain, each element in the Mueller matrix initially set by the sample to be tested is an unknown number or a random number, and the polarization state generator and the polarization state analyzer are used for transforming the column vector X
And (4) showing.
Step two, calculating coefficients of the column vector X 'under psi' as base expression
Namely, it is
Wherein the content of the first and second substances,
represents the pseudo-inverse, then
The simulated spectral analysis result obtained by calculation is phi '. X', namely
Wherein Ψ' is an orthogonal basis composed of Legendre polynomials,
wherein x isiIn [ -1,1 [)]And uniformly sampling.
Step three, rewriting the spectral analysis result of the detector in the system into a column vector
Iterative optimization
Obtaining the coefficient
Wherein | | | purple hairpRepresenting p-norm, coefficient
Is initially calculated by
Calculating to obtain; by
And obtaining a column vector X' so as to obtain a Mueller matrix of the sample to be detected.
(III) spectrum polarization imaging endoscopic system modulated by far-end frequency domain
The light source 101 is an artificial light source with a certain bandwidth, light beams generated by the light source 101 are coupled to the collimator 103 in a rigid or flexible manner such as a lens, a liquid light guide, and an optical fiber, the collimated light beams sequentially pass through the linear polarizer 201, the birefringent crystal 202, and the birefringent crystal 203 in the polarization state generator, and are irradiated onto the sample 701 to be measured via the condenser 104, the sample 701 to be measured can be a transmission sample to be measured and a reflection sample to be measured, for the transmission sample to be measured, the light source and the polarization state analyzer are located at two sides of the sample to be measured, for the reflection sample to be measured, the light source and the polarization state analyzer are located at the same side of the sample to be measured, light beams from the sample to be measured sequentially pass through the birefringent crystal 301, the birefringent crystal 302, and the linear polarizer 303 in the objective lens 401 and the polarization state analyzer, and, the detector 404 performs a spectral analysis of the received light beam and sends the analysis result to the data processing module 501.
In a preferred configuration, the transmission axis directions of the linear polarizer 201 and the linear polarizer 303 are the same, the fast axis direction of the birefringent crystal 202, 302 and the transmission axis direction of the linear polarizer 201, 303 form an angle of 45 degrees, the fast axis direction of the birefringent crystal 203, 301 and the transmission axis direction of the linear polarizer 201, 303 are the same, the thickness ratio of the birefringent crystal 202, 203, 301, 302 is 1:2:5:10, the birefringent crystal 301, 302 can be quartz crystal, calcite crystal, yttrium vanadate crystal, etc., a preferred birefringent crystal material is yttrium vanadate crystal, which has higher birefringence and smaller thickness, and can further reduce the system volume.
The data processing module 501 rewrites the Mueller matrix initially set by the sample to be tested into a column vector X ', and represents the transformation action of the polarization state generator and the polarization state analyzer on the column vector X ' by phi '; calculating coefficients of the column vector X' in a representation based on the matrix Ψ
By varying said coefficients with phi' unchanged
Obtaining simulated spectral analysis results under different Mueller matrix input conditions to obtain
Represents; in the coefficient
Is used as a regular term constraint, and the coefficient is optimized through iteration
The simulated spectral analysis result
Obtaining a coefficient closest to and corresponding to the spectral analysis result of the detector
Value of (A)
Finally utilize
And calculating to obtain a Mueller matrix of the sample to be detected. The method comprises the following specific steps:
step one, a Mueller matrix of a sample to be detected
Rewriting to column vectors
Wherein, v represents the frequency domain,
indicating that the Mueller matrix is a real matrix of 4 × 4, wherein the system has N sampling points in the modulation domain, each element in the Mueller matrix initially set by the sample to be tested is an unknown number or a random number, and the polarization state generator and the polarization state analyzer are used for transforming the column vector X
And (4) showing.
Step two, calculating coefficients of the column vector X 'under psi' as base expression
Namely, it is
Wherein the content of the first and second substances,
represents the pseudo-inverse, then
The simulated spectral analysis result obtained by calculation is phi '. X', namely
In the second step, Ψ' is an orthogonal basis formed by Legendre polynomials,
wherein L is the order of Legendre polynomial, Pn′(xi) In the form of a Legendre polynomial,
wherein x isiIn [ -1,1 [)]And uniformly sampling.
Step three, rewriting the spectral analysis result of the detector in the system into a column vector
Iterative optimization
Obtaining the coefficient
Wherein | | | purple hairpRepresenting p-norm, coefficient
Is initially calculated by
Calculating to obtain; by
And obtaining a column vector X' so as to obtain a Mueller matrix of the sample to be detected.
In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The spectral polarization detection system of frequency domain modulation is characterized by comprising a polarization state analyzer, a detector and a data processing module;
the polarization state analyzer consists of a fixed birefringent crystal and a fixed linear polarizer;
the light beam to be detected sequentially penetrates through the birefringent crystal and the linear polaroid and is received by the detector, and the detector performs spectral analysis on the received light beam and sends an analysis result to the data processing module;
the data processing module rewrites the Stokes vector initially set by the light beam to be measured into a column vector X, and the transformation action of the polarization state analyzer on the column vector X is expressed by phi; calculating coefficients of the column vector X under the expression that the matrix psi is base
By varying said coefficients with constant phi
Obtaining simulated spectral analysis results under different Stokes vector input conditions to
Represents; in the coefficient
Is used as the regular term constraint, the coefficient is optimized by iteration
The simulated spectral analysis result
Obtaining a coefficient closest to and corresponding to the spectral analysis result of the detector
Value of (A)
Finally utilize
And obtaining the Stokes vector of the light beam to be detected.
2. The spectral polarization detection system of frequency domain modulation is characterized by comprising a polarization state analyzer, a polarization state generator, a detector and a data processing module;
the polarization state generator and the polarization state analyzer are both composed of a fixed linear polarizer and a fixed birefringent crystal;
the light beams sequentially penetrate through the linear polarizer and the birefringent crystal of the polarization state generator and then irradiate the sample to be detected, the light beams from the sample to be detected sequentially penetrate through the birefringent crystal and the linear polarizer of the polarization state analyzer and are received by the detector, and the detector performs spectral analysis on the received light beams and sends the analysis result to the data processing module;
the data processing module rewrites a Mueller matrix initially set by a sample to be tested into a column vector X ', and the transformation action of the polarization state generator and the polarization state analyzer on the column vector X ' is represented by phi '; calculating coefficients of the column vector X' in a representation based on the matrix Ψ
By varying said coefficients with phi' unchanged
Obtaining simulated spectral analysis results under different Mueller matrix input conditions to obtain
Represents;in the coefficient
Is used as the regular term constraint, the coefficient is optimized by iteration
The simulated spectral analysis result
Obtaining a coefficient closest to and corresponding to the spectral analysis result of the detector
Value of (A)
Finally utilize
And obtaining a Mueller matrix of the sample to be detected.
3. The frequency domain modulated spectral polarization detection system of claim 2, further comprising a collimating lens, a condensing lens, an objective lens, and an imaging lens;
the polarization state generator and the polarization state analyzer are both positioned at the far end of the system, namely close to a sample to be detected;
the polarization state generator is positioned in a parallel light path between the collimating mirror and the collecting mirror;
the polarization state analyzer is positioned in a parallel light path between the objective lens and the image forming lens;
after being coupled to a collimating mirror in a rigid or flexible mode, a light beam sequentially passes through a polarization state generator and a condenser mirror and then irradiates a sample to be measured; light beams from a sample to be detected pass through the objective lens and the polarization state analyzer and are focused on the detector by the image condenser, the detector performs spectral analysis on the received light beams, and an analysis result is sent to the data processing module.
4. A spectral polarization detection method using frequency domain modulation applied to the system of claim 1, comprising the steps of:
step one, rewriting a Stokes vector S initially set by a light beam to be detected into a column vector X, and expressing the transformation action of the system on the column vector X by phi;
step two, calculating coefficients of the column vector X under the expression with the matrix psi as the base
Namely, it is
Wherein the content of the first and second substances,
represents the pseudo-inverse, then
By changing X, i.e. the coefficient, with phi constant
The simulated spectral analysis results under different Stokes vector inputs are obtained as phi X, i.e.
Step three, rewriting the spectral analysis result output by the detector of the system into a column vector Y, and performing iterative optimization
Obtaining the coefficient
Wherein | | | purple hairpRepresents a p-norm; by passing
And obtaining a column vector X, and further obtaining a Stokes vector of the light beam to be detected.
5. The method for detecting spectral polarization of frequency-domain modulation according to claim 4, wherein in step one, the initial value of the Stokes vector S is determined by
And (4) calculating.
6. The method according to claim 4, wherein in step two, the coefficients
Is initially calculated by
Calculating to obtain; Ψ is an orthogonal basis constituted by Legendre polynomials,
Ψ＝diag(P…P)
Pn(xi) Is a legendre polynomial, N is 1,2,., L, i is 1, 2., N,
wherein x isiIn [ -1,1 [)]And uniformly sampling.
7. A spectral polarization detection method using frequency domain modulation applied to the system of claim 2, comprising the steps of:
step one, rewriting a Mueller matrix M initially set by a sample to be detected into a column vector X ', and expressing the transformation effect of the system on the column vector X ' by phi ';
step two, calculating coefficients of the column vector X 'under psi' as base expression
Namely, it is
Wherein the content of the first and second substances,
represents the pseudo-inverse, then
By changing X ', i.e. changing the coefficient, with phi' unchanged
The simulated spectral analysis results under different Mueller matrix inputs are obtained as phi '. X', that is
Step three, rewriting the spectral analysis result output by the detector of the system into a column vector Y', and performing iterative optimization
Obtaining the coefficient
Wherein | | | purple hairpRepresents a p-norm; by passing
And obtaining a column vector X' so as to obtain a Mueller matrix of the sample to be detected.
8. A frequency domain modulated light as claimed in claim 7The spectral polarization detection method is characterized in that in the step one, the initial value of the Mueller matrix M is determined by
And (4) calculating.
9. The method according to claim 7, wherein in step two, the coefficients
Is initially calculated by
Calculating to obtain; Ψ' is an orthogonal basis composed of Legendre polynomials,
Ψ′＝diag(P′…P′)
Pn′(xi) Is a legendre polynomial, N is 1,2,., L, i is 1, 2., N,
wherein x isiIn [ -1,1 [)]And uniformly sampling.
10. The method for spectral polarization detection with frequency domain modulation according to any of claims 4-9, wherein in step three, p-1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910766902.9A CN110514598B (en) | 2019-08-20 | 2019-08-20 | Spectral polarization detection system and detection method for frequency domain modulation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910766902.9A CN110514598B (en) | 2019-08-20 | 2019-08-20 | Spectral polarization detection system and detection method for frequency domain modulation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110514598A CN110514598A (en) | 2019-11-29 |
| CN110514598B true CN110514598B (en) | 2020-07-14 |
Family
ID=68626715
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910766902.9A Active CN110514598B (en) | 2019-08-20 | 2019-08-20 | Spectral polarization detection system and detection method for frequency domain modulation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110514598B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113295278B (en) * | 2021-05-21 | 2022-07-05 | 北京理工大学 | High-precision Stokes-Mueller channel spectral polarization detection system |
| CN113884466A (en) * | 2021-08-30 | 2022-01-04 | 清华大学深圳国际研究生院 | Surface refractive index imaging sensor based on weak measurement and measurement method thereof |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101793558B (en) * | 2010-03-18 | 2014-04-30 | 西安交通大学 | Device for detecting full polarization of passive and static coaxial interference imaging spectrum |
| CN104161493B (en) * | 2014-07-22 | 2016-04-20 | 清华大学深圳研究生院 | Polarization imaging endoscopic system and endoscopic imaging method |
| CN104535189A (en) * | 2014-12-31 | 2015-04-22 | 中国人民解放军63655部队 | Coaxial static space frequency modulation full-polarization imaging detector |
| CN104535190A (en) * | 2014-12-31 | 2015-04-22 | 中国人民解放军63655部队 | Corner shearing type spatial frequency modulation full-polarization imaging detecting device |
| CN106725250A (en) * | 2017-01-09 | 2017-05-31 | 清华大学深圳研究生院 | Polarized imaging system and measuring method are peeped in a kind of head end modulation |
| CN108593105A (en) * | 2017-12-14 | 2018-09-28 | 南京理工大学 | The Hyperspectral imaging devices and its imaging method of birefringent polarizing interference-type |
| CN108871579B (en) * | 2018-04-27 | 2020-11-13 | 北京理工大学 | Calibration method of polarization imaging system |
| CN108956097B (en) * | 2018-07-10 | 2020-07-31 | 北京理工大学 | Light field polarization state measuring method and device, computer equipment and storage medium |
-
2019
- 2019-08-20 CN CN201910766902.9A patent/CN110514598B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN110514598A (en) | 2019-11-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7130047B2 (en) | Method of producing polarizers for polarized optical probes | |
| US7239388B2 (en) | Retardance measurement system and method | |
| US20190137932A1 (en) | Wide-field imaging of birefringent crystals and other materials using lens-free polarized microscope | |
| CN110514598B (en) | Spectral polarization detection system and detection method for frequency domain modulation | |
| JP4556463B2 (en) | Birefringence measuring device | |
| CN108871579A (en) | A kind of scaling method of polarized imaging system | |
| EP1693658B1 (en) | Spectroscopic polarimetry | |
| CN109901281B (en) | Mueller microscopic polarization aberration calibration method and device | |
| US7187442B2 (en) | Polarized optical probes | |
| CN104161493A (en) | Polarization imaging endoscope system and endoscopic imaging method | |
| CN108828757B (en) | Microscope optical path system, microscope, calibration method, device, equipment and medium | |
| US6501548B1 (en) | Retardance measurement method | |
| WO2018126497A1 (en) | Tip-modulated endoscopic polarization imaging system and measuring method | |
| Zhang et al. | Analyzing the influence of oblique incidence on quantitative backscattering tissue polarimetry: a pilot ex vivo study | |
| US20220390656A1 (en) | High-quality-factor metasurface for phase contrast imaging and spatial frequency filtering | |
| CN113295278B (en) | High-precision Stokes-Mueller channel spectral polarization detection system | |
| Oldenbourg | Analysis of microtubule dynamics by polarized light | |
| US20050068529A1 (en) | Performing retardation measurements | |
| CN113654997B (en) | High-resolution-high-precision Stokes-Mueller imager and calibration method thereof | |
| Arteaga et al. | Mueller Matrix Imaging | |
| Zhang et al. | Analyzing the influence from oblique incidence on quantitively backscattering Mueller matrix polarimetry: a pilot ex-vivo tissue study | |
| KR102553788B1 (en) | Microscope system for quantifying birefringence of sample | |
| Timofeeva et al. | Accelerating imaging frequency in high-speed polarization imaging through data modeling | |
| CN107543684B (en) | A kind of device and method measuring optical window birefringence effect | |
| JP2009085887A (en) | Measuring device and method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |