WO2016173399A1 - 宽波段消色差复合波片的定标方法和装置及相应测量系统 - Google Patents

宽波段消色差复合波片的定标方法和装置及相应测量系统 Download PDF

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WO2016173399A1
WO2016173399A1 PCT/CN2016/079225 CN2016079225W WO2016173399A1 WO 2016173399 A1 WO2016173399 A1 WO 2016173399A1 CN 2016079225 W CN2016079225 W CN 2016079225W WO 2016173399 A1 WO2016173399 A1 WO 2016173399A1
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matrix
wave plate
composite wave
alignment angle
composite
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PCT/CN2016/079225
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English (en)
French (fr)
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钟凤娇
高海军
党江涛
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睿励科学仪器（上海）有限公司
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Priority to KR1020177031458A priority Critical patent/KR101968182B1/ko
Priority to US15/570,557 priority patent/US10309834B2/en
Publication of WO2016173399A1 publication Critical patent/WO2016173399A1/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
    • G01J4/00—Measuring polarisation of light
    • G01J4/04—Polarimeters using electric detection means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/02—Testing optical properties
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
    • 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
    • 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
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
    • G01N21/274—Calibration, base line adjustment, drift correction

Definitions

  • the present patent application relates to the field of polarization optical detection technology, and in particular to a method for wide-band achromatic composite wave plate calibration for Mueller matrix measurement.
  • Mueller matrix measurement is one of the most important methods of polarization detection.
  • the Mueller matrix is a 4 ⁇ 4 matrix, which describes the polarization effects and characteristics of optical devices and materials. It contains polarization information of almost all materials under test and is widely used. In the fields of materials, biology, semiconductors, etc., especially in the measurement of critical dimensions of semiconductor processes, it is an important basis for overcoming the defects of existing measurement techniques and measuring the critical dimension of the next generation process.
  • the Mueller matrix measurement system generally consists of a polarization generator, a sample to be tested, a polarization analyzer and a detector.
  • the polarization generator and the polarization analyzer are similar in structure, usually composed of a combination of a polarization device and a phase compensation device.
  • the phase compensation device is generally a wave plate, a photoelastic modulator, or a liquid crystal modulator.
  • phase compensation devices in Mueller matrix measurements are required to operate over a very wide band, and the resulting phase compensation can be limited to a small range, ie achromatic, over a wide range of wavelengths. Widely used is an achromatic composite wave plate, which has the characteristics of compact size, simple structure, and easy adjustment of light path.
  • An achromatic composite wave plate typically consists of two or more individual wave plates.
  • Wave plate is Optical components commonly used in the field of optical instrument design and optical measurement, also known as optical phase retarders, enable additional phase differences in the two vertical components of polarized light to change or examine the polarization state of the light wave.
  • Wave plates are usually made of uniaxial or biaxial crystal materials, and the materials used to make the wave plates are usually quartz, magnesium fluoride, mica, gypsum, sapphire, and the like.
  • a wave plate composed of a single wave plate is a single wave plate, and a wave plate composed of two or more wafers is a composite wave plate.
  • the corresponding achromatic composite wave plate is designed according to the specific requirements.
  • the optical axes of the individual wave plates constituting the composite wave plate are required to be in accordance with the design.
  • the angle is strictly aligned.
  • the accuracy of the alignment is difficult to ensure, and the alignment angle and the design angle are always different. Therefore, the polarization performance of the actually produced achromatic composite wave plate (that is, the Mueller matrix of the composite wave plate) is different from the ideal Mueller matrix of the design, and must be accurately scaled in the instrument measurement.
  • Some existing methods for calibrating optical components in the Mueller matrix measurement system have not separately considered the problem of wave plate calibration in the case of misalignment of the optical wave plate of the composite wave plate. It is generally considered that the composite wave plate is an ideal wave plate. Only the phase delay amount is calibrated, but in practical applications, especially in the Mueller matrix measurement system, the influence of optical axis misalignment must be considered.
  • An aspect of the invention discloses a calibration method for a composite wave plate, comprising: A. determining a first matrix characterizing the composite wave plate, the first matrix comprising at least one unknown; B. a first matrix determining a relationship between a theoretical light intensity and an alignment angle deviation value of the composite wave plate; C. based on the theoretically determined light intensity determined in step (B) and the alignment of the composite wave plate The relationship between the angular deviation values and the actual measured light intensity data is scaled to obtain a second matrix capable of characterizing the composite wave plate and containing no unknowns.
  • the at least one unknown includes an alignment angle deviation value.
  • the step A further comprises: determining, according to a third matrix representing the single wave plate in the composite wave plate and a coordinate transformation matrix determined by an alignment angle design value and the alignment angle deviation value.
  • the first matrix is a third matrix representing the single wave plate in the composite wave plate.
  • the step A further includes: determining the third matrix based on a characteristic parameter of the single wave plate, wherein the feature parameter comprises at least one of the following: a number of slices of a single wave plate; The material of the single wave plate; and the thickness of each of the single wave plates.
  • the step B further comprises: constructing a functional relationship between the matrix elements in the first matrix and the alignment angle deviation values, such that each matrix element corresponds to the alignment angle deviation value.
  • the step C further comprises: determining the alignment angle deviation value based on the at least one wavelength, thereby determining an unknown matrix element in the first matrix to determine the second matrix.
  • Another aspect of the present invention also discloses an apparatus for calibration of a composite wave plate, comprising: a detecting unit for receiving or detecting the measured light intensity; and a processing unit configured to: determine the characterizing a first matrix of composite wave plates, the first matrix comprising at least one unknown; determining, based on the first matrix, a relationship between a theoretical light intensity and an alignment angle deviation value of the composite wave plate; Determining a relationship between the theoretical light intensity and the alignment angle deviation value of the composite wave plate and the measured light intensity data, determining a second matrix capable of characterizing the composite wave plate.
  • the processing unit is further configured to: determine the first matrix based on a characteristic parameter of the composite wave plate, wherein a characteristic parameter of the composite wave plate includes at least one of the following: a single wave The number of sheets, the material of each of the single wave sheets, the thickness of each of the single wave sheets, and the alignment angle design value of the composite wave plate.
  • the processing unit is further configured to: construct a functional relationship between the matrix elements in the first matrix and the alignment angle deviation values such that each matrix element is only the alignment angle deviation value function.
  • the processing unit is further configured to determine the alignment angle deviation value based on the at least one wavelength to determine a matrix element in the first matrix.
  • the invention also proposes a measurement system comprising: a polarizer for generating polarized light based on a light source; an analyzer for detecting the polarized light reflected from a surface of the sample; and a detector for Receiving light intensity of the polarized light from the analyzer, wherein the measuring system further comprises: at least one composite wave plate disposed between the polarizer and the analyzer according to an optical path, And the measuring system is configured to: adjust the polarizer and/or the composite wave plate and/or the analyzer to adjust the detected light intensity of the detector, and based on theoretical light intensity The relationship between the alignment angle deviation values of the composite wave plates is used to determine a matrix characterizing the composite wave plates.
  • the measurement system is further configured to: determine a characterization based on a matrix characterizing the single wave plate in the composite wave plate and a coordinate transformation matrix determined by an alignment angle design value and the alignment angle deviation value A matrix of the composite wave plates.
  • the measurement system is further configured to: construct a correspondence between matrix elements in the matrix characterizing the composite wave plate and the alignment angle deviation value, such that each matrix element is only the alignment The function of the angle deviation from the value.
  • the measuring system is further configured to: after performing Fourier decomposition on the measured light intensity, and then determining a matrix characterizing the composite wave plate based on a theoretical light intensity value and a wavelength of the light ray;
  • the optical axis direction of the first single wave plate of the composite wave plate is the difference between the system coordinate systems of the measurement system.
  • a computer program product is provided, which is executed when the computer program product is executed by a computer device.
  • a non-transitory computer readable medium comprising computer code, any of the foregoing methods being executed when the computer code is executed.
  • a computer device comprising a memory and a processor, the memory storing computer code, the processor being configured to execute the computer code Perform any of the above methods.
  • the technical solution of the invention when the composite wave plate or the measurement system is calibrated, the number of unknowns can be greatly reduced, thereby reducing the difficulty of calibration and improving the accuracy of calibration.
  • FIG. 1 is a flow chart of a calibration method according to an embodiment of the present invention.
  • FIG. 2 is a block diagram of a measurement system using a composite wave plate in accordance with an embodiment of the present invention.
  • Computer device also referred to as “computer” in the context, is meant an intelligent electronic device that can perform predetermined processing, such as numerical calculations and/or logical calculations, by running a predetermined program or instruction, which can include a processor and Memory, executed by the processor The pre-stored surviving instructions in the memory are used to execute a predetermined process, or are executed by hardware such as an ASIC, an FPGA, a DSP, or the like, or a combination of the two.
  • Computer devices include, but are not limited to, servers, personal computers, notebook computers, tablets, smart phones, and the like.
  • the object of the present invention is to provide a calibration method for a composite wave plate in consideration of the deviation of the optical axis alignment degree of the achromatic composite wave plate.
  • the Mueller matrix of the composite wave plate can be expressed as:
  • the calibration wave plate is to obtain the unknown Mueller matrix elements of m 22 to m 44 , and each matrix element is a function of wavelength.
  • Each wavelength corresponds to a matrix, ie 9 unknowns, that is, work.
  • the waveplate calibration has 9N calibration unknowns.
  • the first disadvantage of this calibration is that there are more unknowns that need to be scaled. It is generally not possible to scale all unknowns at the same time.
  • a mathematical fitting analysis is performed at one wavelength. Not only is the calculation amount large, but the available information is relatively small, and the unknown quantity is relatively large. The accuracy and accuracy of each unknown quantity are difficult to guarantee.
  • the present invention proposes an improved calibration method: instead of considering the achromatic composite wave plate as a single whole, it analyzes its composition and characteristics, and first obtains a matrix expression of its own. The form (ie, the first matrix), based on the first matrix, reduces the unknowns, thereby simplifying the calibration method.
  • a calibration method for a composite wave plate comprising: A. determining a first matrix characterizing the composite wave plate; B. determining a theoretical light intensity based on the first matrix The relationship between the alignment angle deviation values of the composite wave plate; C. based on the relationship between the theoretical light intensity determined in step (B) and the alignment angle deviation value of the composite wave plate, and the measurement
  • the intensity data is scaled to characterize a second matrix of the composite waveplate.
  • the achromatic composite wave plate is composed of two or more optical axes of the same material or single wave plates of different materials at a certain angle.
  • the single wave of the two optical axes perpendicular to each other is perpendicular to each other.
  • a composite wave plate in which the sheets are combined is taken as an example. It can be understood that the method proposed in this embodiment can also be applied to achromatic composite wave plates of different materials, different number of sheets, and various optical axis alignment angles.
  • FIG. 1 is a flow chart of a calibration method in accordance with an embodiment of the present invention.
  • Step S11 determining the composition of the composite wave plate to be scaled
  • the achromatic composite wave plate is composed of a plurality of single wave plates, and the Mueller matrix form of the single wave plate is determined, it is necessary to first determine the matrix form of the single wave plate, and then determine the composite wave plate matrix form. .
  • Step S12 determining a matrix form of the composite wave plate by using a matrix of single wave plates and a coordinate transformation matrix determined by an alignment angle design value and an alignment angle deviation value.
  • the characteristic parameters based on the single wave plate such as the number of single wave plates, the thickness of the material and the single wave plate, are determined by combining the coordinate transformation matrix between the alignment angle design value and the alignment angle deviation value.
  • the matrix form of the composite wave plate is determined by combining the coordinate transformation matrix between the alignment angle design value and the alignment angle deviation value.
  • Step S13 obtaining the measured light intensity and the unknown light based on the matrix of the composite wave plate The theoretical expression of the axis alignment angle deviation value.
  • Step S14 The measured system light intensity data
  • measurements are made through existing wave plates and other optical components such as analyzers, analyzers, and the like.
  • Step S15 analyzing the measured light intensity and the theoretical light intensity to determine the alignment angle deviation value, and finally obtaining a matrix of the composite wave plate.
  • the mathematical expression analysis is performed by the theoretical expression of the light intensity and the actual measured data, and the amount of the required calibration, that is, the deviation angle of the optical axis alignment angle is obtained, and the deviation value is substituted into the matrix expression of the composite wave plate.
  • the matrix of the composite wave plate is obtained, and the calibration is completed.
  • Equation (2) is the Mueller matrix of a single wave plate, where ⁇ is the phase delay it produces and is a function of wavelength:
  • n o and n e are the refractive indices of the birefringent material parallel to the optical axis direction and perpendicular to the optical axis direction, respectively, and d is the thickness of the wave plate.
  • the composite wave plate composed of two single wave plates has the optical axis aligned vertically (ie, 90 degrees), and the optical axis direction of the first wave plate is the direction of the system coordinate system, and the Mueller matrix is:
  • the matrix of two single-wave plates are each:
  • n o1 , n e1 and n o2 , n e2 are the respective refractive indices of the two materials, which are functions of wavelength, so the Mueller matrix of a single wave plate has a matrix at each wavelength, and each wavelength corresponds to a different matrix. .
  • the matrix R( ⁇ ) is a rotation matrix between the optical element coordinate axis and the system coordinate axis, and its form is:
  • Equation (5) the nine unknowns of m 22 to m 44 in equation (1) are not independent of each other, but the optical axis alignment angle deviation value C ⁇ and the refractive index and thickness of the wave plate material itself.
  • the function (the formula of ⁇ 1,2 is shown in equation (3)).
  • the matrix element of the waveplate is a function of the angular deviation from the value C ⁇
  • C ⁇ is not a function of wavelength, it is a value for all wavelengths, so that the unknown of the entire system is from 9N (assumed measurement) N wavelengths have become one.
  • the measurement data (ie, the light intensity) is mathematically fitted to the theoretical formula to obtain the unknown quantity that needs to be scaled.
  • the matrix element of the wave plate is used by the formula ( 5) indicates that the theoretical formula obtained is the same at each wavelength.
  • the refractive indices are different at different wavelengths, the values of the matrix elements are different at each wavelength, but the unknown number of the equation has only one C ⁇ and is independent of wavelength. . Therefore, the data of each wavelength can be used to scale C ⁇ , the amount of data is large, the amount of unknown is small, the difficulty of calibration is reduced, the accuracy and accuracy are correspondingly improved.
  • the above example is an example of a composite wave plate composed of two separate wave plates of different materials.
  • the optical axes are 90 degrees with each other.
  • the optical axis design angle is any one.
  • the calibration method is also applicable, or the matrix expression of the composite wave plate is obtained from the single wave plate.
  • each matrix element is only a function of the alignment angle deviation value. . If the number of wave plates increases, the number of unknowns will increase, and one more wave plate will have an offset angle unknown value, but even then, the number of unknowns is much less than that of 9N.
  • the measuring system includes: a polarizer 1 for generating polarized light based on a light source; A composite wave plate 2 is disposed between the polarizer and the sample according to an optical path; an analyzer 4 and a detector 5 for receiving an optical signal from the analyzer.
  • the measuring system is configured to: adjust at least one of the polarizer 1, the first composite wave plate 2, and the analyzer 4 to adjust the light intensity data obtained by the detector 5, and based on the theoretical light intensity and the composite wave plate The relationship between the alignment angle deviation values is used to determine a second matrix capable of characterizing the first composite wave plate.
  • the measurement system is first adjusted so that it can determine the various measurement parameters of the system in the measured state, and the Mueller matrix form of each optical component in the system except the first composite wave plate, in the usual Mueller matrix measurement system.
  • the amount of error of the polarizer is very small and can be considered as an ideal original.
  • Samples can be prepared using a variety of standard samples, such as the bare wafer or a known thickness of S i O 2 film.
  • the light of the light source S passes through the polarizer 1 and enters the first composite wave plate 2 at the incident end, is irradiated to the sample, and is reflected by the sample into the exit end analyzer 4 to enter the detector 5.
  • the polarizer 1 and the first composite wave plate 2 constitute a polarization generator at the incident end, and the analyzer 4 is a polarization detector.
  • the operating mode of the system (the mode of measuring the light intensity) can be varied, such as the measurement of the rotating analyzer 4, or the rotating polarizer 1 or the addition of a composite wave plate 3 (indicated by a broken line in the figure, which can be determined)
  • the labeled wave plate or the wave plate to be determined needs to be rotated, rotate any wave plate or rotate two wave plates at the same time (the rotation speed of the wave plate becomes a certain ratio).
  • the composite wave plate is regarded as a whole, in order to scale the unknown 9 matrix elements (at one wavelength), it is necessary to measure the joints in several working modes to scale as much as possible. Now there is only one unknown.
  • the quantity C ⁇ two unknowns C ⁇ 1 for the two composite plates to be scaled, 2 because the alignment deviation of the two wave plates is different
  • We use the working mode of the rotary analyzer as an example.
  • S 0 is the Stokes amount of the incident light source
  • the Stokes amount is the amount describing the polarization characteristic of the light, which is a 4 ⁇ 1 vector whose first element is the light intensity.
  • S is the amount of Stokes after the light passes through the system, and its first quantity S(1) is the light intensity that we can detect.
  • M p , M A , M S are the polarizer, the Mueller matrix of the analyzer and the sample
  • M Cf1 is the wave plate matrix of the incident end
  • the R matrix is the rotation transformation matrix of the coordinate axis of the component and the system coordinate axis
  • P and A are the angles between the optical axis of the polarizer and the analyzer and the system coordinate axis, respectively.
  • C 1 is the optical axis direction of the first single wave plate and the system coordinate axis of the two single wave plates in the composite wave plate.
  • the angle of the derivation (5) is based on the optical axis direction of the first single-wave plate of the composite wave plate.
  • the hardware installation and debugging requirements are the axes of the system and the system.
  • the direction is the same, but there is also a certain deviation. This deviation is C 1 .
  • C 1 is calculated, which is also a wavelength-independent number. The amount of the target.
  • ⁇ For the angular velocity of the rotation of the analyzer, ⁇ 2 (C ⁇ , C 1 ,), ⁇ 2 (C ⁇ , C 1 ,) is a functional expression of the amount to be scaled.
  • the measured light intensity can be Fourier-decomposed to obtain the experimental ⁇ 2 and ⁇ 2 , and then mathematically fit with the theoretical expressions of the two to obtain the C ⁇ and C 1 , which need to be scaled.
  • a matrix of scaled waves is required. When doing mathematical fitting, it can be obtained by using one wavelength of data. In order to improve the accuracy, data of multiple wavelengths can be used to fit together to obtain the amount to be scaled.
  • the present invention also provides an apparatus for calibration of a composite wave plate, comprising: a detecting unit for receiving or detecting the measured light intensity; and a processing unit configured to: determine the first characterizing the composite wave plate a matrix; based on the first matrix, determining a relationship between a theoretical light intensity and an alignment angle deviation value of the composite wave plate; and based on the determined theoretical light intensity and the alignment angle deviation value of the composite wave plate The relationship and the measured light intensity data determine a second matrix capable of characterizing the composite wave plate.
  • the processing unit is further configured to: determine the first matrix based on the characteristic parameters of the composite wave plate, wherein the characteristic parameters of the composite wave plate comprise at least one of the following: the number of single wave plates, each single wave The material of the sheet, the thickness of each single wave plate; and the alignment angle design value of the composite wave plate.
  • the processing unit is further configured to: construct a functional relationship between the matrix elements in the first matrix and the alignment angle deviation values such that each matrix element is only a function of the alignment angle deviation value.
  • the processing unit is further configured to determine an alignment angle deviation value based on the at least one wavelength, thereby determining a matrix element in the first matrix. It will be appreciated that the more wavelengths used, the more accurate the determined data.
  • the present invention may be implemented in software and/or a combination of software and hardware, for example, an application specific integrated circuit (ASIC), a general purpose computer, or any other similar Hardware devices are implemented.
  • the software program of the present invention may be executed by a processor to implement the steps or functions described above.
  • the software program (including related data structures) of the present invention can be stored in a computer readable recording medium such as a RAM memory, a magnetic or optical drive or a floppy disk and the like.
  • some of the steps or functions of the present invention may be implemented in hardware, for example, as a circuit that cooperates with a processor to perform various steps or functions.
  • a portion of the invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide a method and/or solution in accordance with the present invention.
  • the program instructions that invoke the method of the present invention may be stored in a fixed or removable recording medium, and/or by broadcast or The signal is transmitted by the data stream carried in the medium and/or stored in a working memory of the computer device operating in accordance with the program instructions.
  • an embodiment in accordance with the present invention includes a device including a memory for storing computer program instructions and a processor for executing program instructions, wherein when the computer program instructions are executed by the processor, triggering
  • the apparatus operates based on the aforementioned methods and/or technical solutions in accordance with various embodiments of the present invention.

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Abstract

一种用于复合波片（2、3）的定标方法和装置及相应测量系统，该定标方法包括：（A）.确定表征复合波片（2、3）的第一矩阵，第一矩阵包含至少一个未知数；（B）.基于第一矩阵，确定理论上光强与复合波片（2、3）的对准角度偏离值之间的关系；（C）.基于步骤（B）中已确定的理论上光强与复合波片（2、3）的对准角度偏离值之间的关系以及实际测量得到的光强数据，定标出能够表征复合波片（2、3）且不含未知数的第二矩阵。通过该技术方案，在对复合波片（2、3）或测量系统进行定标时，可以大幅减少未知数的数量，从而降低定标的难度，提高定标的精度。

Description

宽波段消色差复合波片的定标方法和装置及相应测量系统
关联申请的交叉引用
本专利申请要求2015年4月30日提交的名为“宽波段消色差复合波片的定标方法和装置”，编号201510218243.7的中国发明专利申请的优先权，该在先申请的整体通过引用方式并入本申请。
技术领域
本专利申请涉及偏振光学检测技术领域，具体涉及到一种用于穆勒(Mueller)矩阵测量的宽波段消色差复合波片定标的方法。
背景技术
穆勒矩阵测量是偏振检测的重要手段之一，Mueller矩阵为4×4的矩阵，描述的是光学器件和材料的偏振效应和特性，包含了几乎所有的被测材料的偏振信息，被广泛应用于材料、生物、半导体等各个领域，尤其是在半导体工艺关键尺寸的测量中，是克服现有测量技术的缺陷，测量下一代工艺关键尺寸的方法光学关键尺寸测量(OCD)技术的重要基础。
Mueller矩阵测量系统一般主要有偏振发生器、被测样品、偏振分析器和探测器这几个部分组成，其中偏振发生器和偏振分析器结构类似，通常由偏振器件和相位补偿器件组合而成，相位补偿器件一般是波片、光弹调制器或液晶调制器等。通常Mueller矩阵测量中的相位补偿器件，要求其能在非常宽的波段工作，产生的相位补偿在很宽的波段范围内能限制在很小的区间，即消色差。其中广泛使用的是消色差的复合波片，其具有尺寸紧凑，结构简单，光路易调整等特点。
消色差的复合波片通常由两片及以上的单个波片组成。波片是 光学仪器设计与光学测量领域中常用的光学元件，又叫光学相位延迟片，它能够使得偏振光的两个垂直分量产生附加的相位差，从而改变或者检查光波的偏振态。波片通常由单轴或者双轴晶体材料制成，用于制作波片的材料通常有石英、氟化镁、云母、石膏、蓝宝石等。由单个波片组成的波片为单波片，由两片或多片晶片组成的波片为复合波片。
在实际应用中，通常是两种材料的两片单波片复合而成的复合波片，光轴互相垂直。为了特殊的使用需求，也会设计制作更复杂的消色差复合波片，这些复合波片由多片同种材料或者不同材料的单波片组合而成，而且各单片光轴之间的夹角为优化设计的角度值。这些复合波片能够得到很好的消色差结果，这种改善波片精度及消除波片本身色差的性能是单个波片所不能达到的，因此使得复合波片在光学仪器设计与光学测量中获得了广泛的应用。
在实际的应用中，比如Mueller矩阵测量中，针对具体的要求设计相应的消色差复合波片，为了保证仪器测量的精度，要求组成复合波片的各片单波片的光轴按照设计的夹角严格对准。但是在实际生产过程中，不论是手动凭经验进行对准的方式还是消光法的对准方式，对准的精度都难以保证，对准的角度与设计的角度总有一定的差别。因此，实际生产出来的消色差复合波片的偏振性能(也就是复合波片的Mueller矩阵)跟设计的理想的Mueller矩阵有差别，在仪器测量中必须对其进行精确的定标。
现有的一些对Mueller矩阵测量系统中的光学元件进行定标的方法，还没有单独考虑复合波片光轴不对准的情况下波片定标的问题，一般认为复合波片为理想的波片，只定标其相位延迟量，但是在实际应用中，尤其是Mueller矩阵测量系统中，必须考虑光轴不对准的影响。
因此，亟需一种能够用于复合波片的高速、高精度的定标方法。
发明内容
基于以上考虑，因此，亟需一种能够用于复合波片的高速、高精度的定标方法和装置将是十分有利的。
本发明一方面公开了一种用于复合波片的定标方法，其包括：A.确定表征所述复合波片的第一矩阵，所述第一矩阵包含至少一个未知数；B.基于所述第一矩阵，确定理论上光强与所述复合波片的对准角度偏离值之间的关系；C.基于步骤(B)中已确定的理论上光强与所述复合波片的对准角度偏离值之间的关系以及实际测量得到的光强数据，定标得到能够表征所述复合波片且不含未知数的第二矩阵。
优选的，所述至少一个未知数包括对准角度偏离值。
优选的，所述步骤A还包括：基于所述复合波片中的表征单波片的第三矩阵和由对准角度设计值和所述对准角度偏离值决定的坐标变换矩阵来确定所述第一矩阵。
优选的，所述步骤A还包括：基于所述单波片的特征参数，确定所述第三矩阵，其中，所述特征参数包括以下项中的至少一项：单波片的片数；各所述单波片的材料；以及各所述单波片的厚度。
优选的，所述步骤B还包括：构建所述第一矩阵中的矩阵元与所述对准角度偏离值之间的函数关系，使得每个矩阵元与所述对准角度偏离值相对应。
优选的，所述步骤C还包括：基于至少一个波长，确定所述对准角度偏离值，进而确定所述第一矩阵中的未知的矩阵元以确定所述第二矩阵。
本发明另一方面还公开了一种用于复合波片进行定标的装置，其包括：检测单元，用于接收或检测测量到的光强；处理单元，其被配置为：确定表征所述复合波片的第一矩阵，所述第一矩阵包含至少一个未知数；基于所述第一矩阵，确定理论上光强与所述复合波片的对准角度偏离值之间的关系；以及基于已确定的理论上光强与所述复合波片的对准角度偏离值之间的关系以及测量得到的光强数据，确定能够表征所述复合波片的第二矩阵。
优选的，所述处理单元还被配置为：基于所述复合波片的特征参数，确定所述第一矩阵，其中，所述复合波片的特征参数包括以下项中的至少一项：单波片的片数、各所述单波片的材料、各所述单波片的厚度；以及所述复合波片的对准角度设计值。
优选的所述处理单元还被配置为：构建所述第一矩阵中的矩阵元与所述对准角度偏离值之间的函数关系，使得每个矩阵元仅是所述对准角度偏离值的函数。
优选的，所述处理单元还被配置为：基于至少一个波长，确定所述对准角度偏离值，进而确定所述第一矩阵中的矩阵元。
本发明还提出了一种测量系统，包括：起偏器，其用于基于光源而产生偏振光；验偏器，其用于检测自样品表面反射的所述偏振光；探测器，其用于接收来自所述验偏器的所述偏振光的光强；其中，所述测量系统还包括：至少一个复合波片，其被依光学路径设置在所述起偏器与验偏器之间，并且所述测量系统被配置为：调整所述起偏器和/或所述复合波片和/或所述验偏器来调整所述探测器所探测到光强，并且基于理论上光强与复合波片的对准角度偏离值之间的关系来确定表征所述复合波片的矩阵。
优选的，所述测量系统还被配置为：基于所述复合波片中的表征单波片的矩阵和由对准角度设计值和所述对准角度偏离值决定的坐标变换矩阵来确定能够表征所述复合波片的矩阵。
优选的，所述测量系统还被配置为：构建表征所述复合波片的矩阵中的矩阵元与所述对准角度偏离值之间的对应关系，使得每个矩阵元仅是所述对准角度偏离值的函数。
优选的，所述测量系统还被配置为：对测量得到的光强作傅里叶分解后，然后再基于理论上的光强值和光线的波长确定表征所述复合波片的矩阵和/或所述复合波片的第一片单波片的光轴方向所述测量系统的系统坐标系之间的差值。
根据本发明的又一方面的实施例，提供了一种计算机程序产品，当所述计算机程序产品被计算机设备执行时，前述任一方法将被执行。
根据本发明的又一方面的实施例，提供了一种非易失性计算机可读介质，其包括计算机代码，当所述计算机代码被执行时，前述任一方法被执行。
根据本发明的又一方面的实施例，提供了一种计算机设备，所述计算机设备包括存储器和处理器，所述存储器中存储有计算机代码，所述处理器配置为通过执行所述计算机代码来执行前述任一方法。
通过本发明的技术方案，在对复合波片或测量系统进行定标时，可以大幅减少未知数的数量，从而降低定标的难度，提高定标的精度。
本发明的各个方面将通过下文的具体实施例的说明而更加清晰。
附图说明
通过参照附图并阅读以下所作的对非限制性实施例的详细描述，本发明的其它特征、目的和优点将会变得更明显。
图1为依据本发明实施例的定标方法的流程图；
图2为依据本发明实施例的采用复合波片的测量系统架构图。
在图中，贯穿不同的示图，相同或类似的附图标记表示相同或相似的装置(模块)或步骤。
具体实施方式
在以下优选的实施例的具体描述中，将参考构成本发明一部分的所附的附图。所附的附图通过示例的方式示出了能够实现本发明的特定的实施例。示例的实施例并不旨在穷尽根据本发明的所有实施例。可以理解，在不偏离本发明的范围的前提下，可以利用其他实施例，也可以进行结构性或者逻辑性的修改。因此，以下的具体描述并非限制性的，且本发明的范围由所附的权利要求所限定。
在上下文中所称“计算机设备”，也称为“电脑”，是指可以通过运行预定程序或指令来执行数值计算和/或逻辑计算等预定处理过程的智能电子设备，其可以包括处理器与存储器，由处理器执行在存 储器中预存的存续指令来执行预定处理过程，或是由ASIC、FPGA、DSP等硬件执行预定处理过程，或是由上述二者组合来实现。计算机设备包括但不限于服务器、个人电脑、笔记本电脑、平板电脑、智能手机等。
本发明的目的是提供一种考虑消色差复合波片光轴对准度有偏差的情况下复合波片的定标方法，通过减少定标的未知量，降低定标的难度，提高定标的精度。
在不关注消色差复合波片的具体形式，只把它当作一个完整的单独的波片看，光轴对准度有偏差的情况下，复合波片的Mueller矩阵可以表示为：
相应的，定标波片就是要得到未知的m22～m44这9个Mueller矩阵元，且每个矩阵元都是波长的函数，每个波长都对应一个矩阵即9个未知数，也就是工作波长范围很宽有N个波长时，波片定标就有9N个定标未知数。
Mueller测量系统中，通常的定标，采用标准的已知的样品，波片作为未知量，光通过偏振产生器照射到样品然后进入偏振探测器，最后被探测器探测到，测量得到的各个波长下的光强I。确定了光路上各个元件的Mueller矩阵形式以后，可以得到理论上测量得到的光强与光路中的元件Mueller矩阵元有关的表达式，在除了波片其他的矩阵元都已知的情况下，确定波长下测量到的光强为波片矩阵元的函数I＝f(m22…m44)。通过实际测量数据跟理论公式进行数学拟合分析，得到未知的波片的矩阵元。每个波长下的公式一样，但是数值不一样，单独计算每个波长下的数据，得到对应的这个波长下的波片的矩阵元的数值。
显然，这个定标首先一个缺点是需要定标的未知量比较多，系 统一般不能够同时定标到所有的未知量。其次是一个波长下进行一次数学拟合分析，不仅计算量大，且计算可利用的信息比较少，未知量比较多，单独每个未知量的准确度和精度比较难保证。
针对上述的问题，本发明提出了一个改进的定标方法：不把消色差复合波片看成一个单独的整体，而是从它的组成结构、特点来分析，先得到它本身的一个矩阵表达形式(即，第一矩阵)，再基于第一矩阵，减少未知量，从而简化定标方法。
依据本发明实施例的一种用于复合波片的定标方法，其包括：A.确定表征所述复合波片的第一矩阵；B.基于所述第一矩阵，确定理论上光强与所述复合波片的对准角度偏离值之间的关系；C.基于步骤(B)中已确定的理论上光强与所述复合波片的对准角度偏离值之间的关系以及测量得到的光强数据，定标出表征所述复合波片的第二矩阵。
消色差复合波片由两片或以上的同材料或不同材料的单波片光轴成一定的角度组合而成，为了说明原理，本实施例以两片不同材料的光轴互相垂直的单波片组合成的复合波片为例。可以理解的是，本实施例提出的方法还可以适用于不同材料、不同片数，各种光轴对准角度的消色差复合波片。
图1为依据本发明实施例的定标方法的流程图。
步骤S11：确定需定标的复合波片的组成情况；
由于消色差复合波片是由多片单波片组合而成的，而单波片的Mueller矩阵形式是确定的，因此，需要首先确定单波片的矩阵形式，然后再确定复合波片矩阵形式。
步骤S12：利用单波片的矩阵和由对准角度设计值和对准角度偏离值决定的坐标变换矩阵确定复合波片的矩阵形式。
在该步骤中，将基于单波片的特征参数，譬如单波片的片数、材料以及单波片的厚度，结合对准角度设计值和对准角度偏离值之间的坐标变换矩阵，确定复合波片的矩阵形式。
步骤S13：基于复合波片的矩阵，得到测量的光强与未知数光 轴对准角度偏离值的理论表达公式。
在该步骤中，构建所述第一矩阵中的矩阵元与所述对准角度偏离值之间的理论上的函数关系，使得每个矩阵元与所述对准角度偏离值相对应。
步骤S14：实测得到的系统光强数据
在该步骤中，将通过现有的波片以及其他光学组件(譬如，检偏器、验偏器等)进行测量。
步骤S15：将实测的光强与理论的光强进行分析，确定对准角度偏离值，最终得到复合波片的矩阵。
在该步骤中，由光强的理论表达式和实际测量数据进行数学拟合分析，得到需要定标的量即光轴对准角度偏离值，再把偏离值代入得到了复合波片的矩阵表达式，得到复合波片的矩阵，完成定标。
下面对本发明的实施例进行详细说明。
式(2)为单波片的Mueller矩阵，其中Δ是其产生的相位延迟，是波长的函数：
Figure PCTCN2016079225-appb-000002
当波片的材料和厚度已知的情况下，其产生的相位延迟为：
Figure PCTCN2016079225-appb-000003
其中no和ne分别是双折射材料的平行于光轴方向和垂直于光轴方向的折射率，d为波片的厚度。
两片单波片组合成的复合波片，光轴成垂直对准(即成90度)，以第一片波片的光轴方向为系统坐标系方向，其Mueller矩阵为：
Figure PCTCN2016079225-appb-000004
其中两片单波片的矩阵各自为：
Figure PCTCN2016079225-appb-000005
其中，
Figure PCTCN2016079225-appb-000006
no1、ne1和no2、ne2分别是两种材料各自的折射率，其是波长的函数，因此单个波片的Mueller矩阵在每个波长处有一个矩阵，每个波长对应不同的矩阵。
其中矩阵R(θ)为光学元件坐标轴与系统坐标轴之间的转动矩阵，其形式为：
Figure PCTCN2016079225-appb-000007
以第一片单波片的光轴方向为系统坐标系方向，两个波片光轴互为垂直，则θ＝90°。
Figure PCTCN2016079225-appb-000008
当光轴对准度偏离90度，即存在微小的对准角度偏离值CΔ时，复合波片的矩阵变为：
Figure PCTCN2016079225-appb-000009
当CΔ＝0时，式(5)将退化为式(4)的结果，由式(5)可知， 光轴与设计的角度有一定的偏离以后，复合波片的Mueller矩阵就不再是理想的矩阵，原来为零的矩阵元有了数值，非零的矩阵元的值也会改变。因此，必须精确定标出这个复合波片的Mueller矩阵，才能够在系统测量的时候得到比较好的精度，如果不考虑矩阵元的具体形式，而把复合波片当成一个整体，一个波长下就会有9个未知数。
由式(5)可知，式(1)中的m22～m44这9个未知量并不是互相独立的，而是光轴对准角度偏离值CΔ和波片材料自身折射率和厚度的函数(Δ1，2的公式见式(3))。显然，当决定好使用哪种单波片时，其材料、折射率、厚度均已经确定。这样，波片的矩阵元就是对准角度偏离值CΔ的函数，且CΔ并不是波长的函数，对于所有的波长他都是一个数值，这样，整个系统的未知数就从9N个(假设测量N个波长)变为了1个。确定好矩阵(5)的形式后，将测量数据(即，光强)跟理论公式进行数学拟合分析得到需要定标的未知量，推导理论公式的时候，波片的矩阵元就用公式(5)表示，得到的理论公式在每个波长下一样，虽然不同波长下折射率都不一样，矩阵元的数值还是每个波长下都不同，但是公式的未知数就只有一个CΔ且与波长无关。因此，每个波长的数据都可以用来定标CΔ，数据量大，未知量少，定标的难度减小、准确度和精度相应提高。定标得到CΔ后，就可以带入公式(5)得到波片的全部矩阵元。
上面的例子是以材料不同的两片的单独的波片组合成的复合波片为例，光轴互成90度，当复合波片的单波片片数增多，光轴设计角度为任意一角度时，定标的方法也是适用的，还是从单波片出发，得到复合波片的矩阵表达式，在确定材料和对准角度后，每个矩阵元只会是对准角度偏离值的函数。波片片数增多，会增加未知数，多一个波片多一个对准角度偏离值未知数，但是即使这样，比起9N个，未知数少了非常多。
现在以具体的测量系统来说明本发明的具体实施方式，在平行光下测量定标。
测量系统包括：起偏器1，其用于基于光源而产生偏振光；第 一复合波片2，其被依光学路径设置在起偏器与样品之间；验偏器4以及探测器5，其用于接收来自验偏器的光学信号。
测量系统被配置为：调整起偏器1、第一复合波片2、以及验偏器4中的至少一个来调整探测器5得到的光强数据，并且基于理论上光强与复合波片的对准角度偏离值之间的关系来确定能够表征第一复合波片的第二矩阵。
具体地，首先调整好测量系统，使其能够在测量的状态，确定好系统的各个测量参数，以及除了第一复合波片以外系统中各个光学元件的Mueller矩阵形式，在通常的Mueller矩阵测量系统中，起偏器的误差量非常小，可以认为是理想的原件。样品可以采用各种不同的标准样品，这些标准样品的Mueller矩阵已知，比如裸硅片或者已知厚度的SiO2薄膜。
光源S的光经过起偏器1进入入射端的第一复合波片2，照射到样品，经过样品反射进入出射端验偏器4之后进入探测器5。起偏器1和第一复合波片2组成了入射端的偏振产生器，验偏器4为偏振检测器。
系统的工作模式(测量光强的模式)可以有很多种，比如旋转验偏器4测量，或是旋转起偏器1或增加一个复合波片3(图中以虚线表示，其可以是已经定标好的波片或者需要待定标得波片)，旋转任意一个波片或同时旋转两个波片(波片的转动速度成一定的比例)等。如果把复合波片看成一个整体，为了定标未知的9个矩阵元(一个波长下)，必须几种工作模式下都测量联合进行定标才能定标到尽量多的量，现在只有一个未知量CΔ(两个需定标的复合波片时为两个未知量CΔ1，2因为两个波片的对准度偏差不一样)只需要采用任意一种工作模式即可。我们采用旋转验偏器的工作模式为例。
旋转验偏器，得到实验测量的光强。而理论上光强与波片Mueller矩阵元的理论公式推导如下：
Figure PCTCN2016079225-appb-000010
其中S0为入射光源的斯托克斯量，斯托克斯量是描述光的偏振 特性的量，是一个4×1的向量，其第一个元素为光强。S为光经过系统后的斯托克斯量，其第一个量S(1)为我们能够探测到的光强。Mp、MA、MS分别为起偏器，验偏器和样品的Mueller矩阵，MCf1为入射端的波片矩阵，R矩阵为元件的坐标轴与系统坐标轴的旋转变换矩阵，其中，P、A分别为起偏器和验偏器的光轴与系统坐标轴的夹角，C1为复合波片中的两个单波片的第一个单波片光轴方向与系统坐标轴的夹角，在推导式(5)时，是以复合波片的第一片单波片的光轴方向为准的，在系统中时，硬件装调试要求是这个方向需要与系统的坐标轴方向一致，但是也存在一定的偏差，这个偏差就是C1，为了更精确地为整个系统定标，因此，本实施例中把C1计算入内，这个也是与波长无关的数，可作为一起定标的量。
为得到S的第一个元素，即理论上可以测量的得到的光强，当起偏器1的角度P一定时，转动验偏器4测量，这个光强是复合波片的定标量和时间的函数，波片的矩阵用式(5)代入，即光强的形式如下：
I＝I(t)＝S[1]＝I0(1+α2(CΔ,C1)cos(2ωt)+β2(CΔ,C1)sin(2ωt))   (7)其中ω为验偏器转动的角速度，α2(CΔ,C1,)、β2(CΔ,C1,)为需要定标的量的函数表达式。
可以对测量得到的光强作傅立叶分解得到实验的α2、β2，然后跟理论的两者的函数表达式做数学拟合，得到需要定标的CΔ、C1、，也就得到了需要定标的波片的矩阵。做数学拟合时，可以用一个波长的数据就可求出，为了提高精度可以采用多个波长的数据来一起拟合得到需要定标的量。
本发明还提出了一种用于复合波片进行定标的装置，其包括：检测单元，用于接收或检测测量到的光强；处理单元，其被配置为：确定表征复合波片的第一矩阵；基于第一矩阵，确定理论上光强与复合波片的对准角度偏离值之间的关系；以及基于已确定的理论上光强与复合波片的对准角度偏离值之间的关系以及测量得到的光强数据，确定能够表征复合波片的第二矩阵。
优选的，处理单元还被配置为：基于复合波片的特征参数，确定第一矩阵，其中，复合波片的特征参数包括以下项中的至少一项：单波片的片数、各单波片的材料、各单波片的厚度；以及复合波片的对准角度设计值。
优选的，处理单元还被配置为：构建第一矩阵中的矩阵元与对准角度偏离值之间的函数关系，使得每个矩阵元仅是对准角度偏离值的函数。
优选的，处理单元还被配置为：基于至少一个波长，确定对准角度偏离值，进而确定第一矩阵中的矩阵元。可以理解的是，使用的波长越多，确定的数据则越精确。
对于本领域技术人员而言，显然本发明不限于上述示范性实施例的细节，而且在不背离本发明的精神或基本特征的情况下，能够以其他的具体形式实现本发明。因此，无论如何来看，均应将实施例看作是示范性的，而且是非限制性的。此外，明显的，“包括”一词不排除其他元素和步骤，并且措辞“一个”不排除复数。装置权利要求中陈述的多个元件也可以由一个元件来实现。第一，第二等词语用来表示名称，而并不表示任何特定的顺序。需要注意的是，本发明(例如上下文中的定标方法)可在软件和/或软件与硬件的组合体中被实施，例如，可采用专用集成电路(ASIC)、通用目的计算机或任何其他类似硬件设备来实现。在一个实施例中，本发明的软件程序可以通过处理器执行以实现上文所述步骤或功能。同样地，本发明的软件程序(包括相关的数据结构)可以被存储到计算机可读记录介质中，例如，RAM存储器，磁或光驱动器或软磁盘及类似设备。另外，本发明的一些步骤或功能可采用硬件来实现，例如，作为与处理器配合从而执行各个步骤或功能的电路。
另外，本发明的一部分可被应用为计算机程序产品，例如计算机程序指令，当其被计算机执行时，通过该计算机的操作，可以调用或提供根据本发明的方法和/或技术方案。而调用本发明的方法的程序指令，可能被存储在固定的或可移动的记录介质中，和/或通过广播或其 他信号承载媒体中的数据流而被传输，和/或被存储在根据所述程序指令运行的计算机设备的工作存储器中。在此，根据本发明的一个实施例包括一个装置，该装置包括用于存储计算机程序指令的存储器和用于执行程序指令的处理器，其中，当该计算机程序指令被该处理器执行时，触发该装置运行基于前述根据本发明的多个实施例的方法和/或技术方案。

Claims (17)

  1. 一种用于复合波片的定标方法，其特征在于，包括：
    A.确定表征所述复合波片的第一矩阵，所述第一矩阵包含至少一个未知数；
    B.基于所述第一矩阵，确定理论上光强与所述复合波片的对准角度偏离值之间的关系；
    C.基于步骤(B)中已确定的理论上光强与所述复合波片的对准角度偏离值之间的关系以及实际测量得到的光强数据，定标得到能够表征所述复合波片且不含未知数的第二矩阵。
  2. 根据权利要求1所述的方法，其特征在于，所述至少一个未知数包括对准角度偏离值。
  3. 根据权利要求1所述的方法，其特征在于，所述步骤A还包括：
    基于所述复合波片中的表征单波片的第三矩阵和由对准角度设计值和所述对准角度偏离值决定的坐标变换矩阵来确定所述第一矩阵。
  4. 根据权利要求3所述的方法，其特征在于，所述步骤A还包括：
    基于所述单波片的特征参数，确定所述第三矩阵，其中，所述特征参数包括以下项中的至少一项：
    单波片的片数；
    各所述单波片的材料；以及
    各所述单波片的厚度。
  5. 根据权利要求1所述的方法，其特征在于，所述步骤B还包括：
    构建所述第一矩阵中的矩阵元与所述对准角度偏离值之间的函数关系，使得每个矩阵元与所述对准角度偏离值相对应。
  6. 根据权利要求1所述的方法，其特征在于，所述步骤C还包 括：
    基于至少一个波长，确定所述对准角度偏离值，进而确定所述第一矩阵中的未知的矩阵元以确定所述第二矩阵。
  7. 一种用于复合波片进行定标的装置，其特征在于，包括：
    检测单元，用于接收或检测测量到的光强；
    处理单元，其被配置为：
    确定表征所述复合波片的第一矩阵，所述第一矩阵包含至少一个未知数；
    基于所述第一矩阵，确定理论上光强与所述复合波片的对准角度偏离值之间的关系；以及
    基于已确定的理论上光强与所述复合波片的对准角度偏离值之间的关系以及测量得到的光强数据，确定能够表征所述复合波片的第二矩阵。
  8. 根据权利要求7所述的装置，其特征在于，所述处理单元还被配置为：
    基于所述复合波片的特征参数，确定所述第一矩阵，其中，所述复合波片的特征参数包括以下项中的至少一项：
    单波片的片数、
    各所述单波片的材料、
    各所述单波片的厚度；以及
    所述复合波片的对准角度设计值。
  9. 根据权利要求7所述的装置，其特征在于，所述处理单元还被配置为：
    构建所述第一矩阵中的矩阵元与所述对准角度偏离值之间的函数关系，使得每个矩阵元仅是所述对准角度偏离值的函数。
  10. 根据权利要求7所述的装置，其特征在于，所述处理单元还被配置为：
    基于至少一个波长，确定所述对准角度偏离值，进而确定所述第一矩阵中的矩阵元。
  11. 一种测量系统，其特征在于，包括：
    起偏器，其用于基于光源而产生偏振光；
    验偏器，其用于检测自样品表面反射的所述偏振光；
    探测器，其用于接收来自所述验偏器的所述偏振光的光强；
    其中，所述测量系统还包括：
    至少一个复合波片，其被依光学路径设置在所述起偏器与验偏器之间，并且所述测量系统被配置为：
    调整所述起偏器和/或所述复合波片和/或所述验偏器来调整所述探测器所探测到光强，并且基于理论上光强与复合波片的对准角度偏离值之间的关系来确定表征所述复合波片的矩阵。
  12. 根据权利要求11所述的测量系统，其特征在于，所述测量系统还被配置为：
    基于所述复合波片中的表征单波片的矩阵和由对准角度设计值和所述对准角度偏离值决定的坐标变换矩阵来确定能够表征所述复合波片的矩阵。
  13. 根据权利要求12所述的测量系统，其特征在于，所述测量系统还被配置为：
    构建表征所述复合波片的矩阵中的矩阵元与所述对准角度偏离值之间的对应关系，使得每个矩阵元仅是所述对准角度偏离值的函数。
  14. 根据权利要求11所述的测量系统，其特征在于，所述测量系统还被配置为：
    对测量得到的光强作傅里叶分解后，然后再基于理论上的光强值和光线的波长确定表征所述复合波片的矩阵和/或所述复合波片的第一片单波片的光轴方向所述测量系统的系统坐标系之间的差值。
  15. 一种计算机程序产品，当所述计算机程序产品被计算机设备执行时，如权利要求1-6中任一项所述的方法被执行。
  16. 一种非易失性计算机可读介质，其包括计算机代码，当所述计算机代码被执行时，如权利要求1-6中任一项所述的方法被执行。
  17. 一种计算机设备，所述计算机设备包括存储器和处理器，所述存储器中存储有计算机代码，所述处理器配置为通过执行所述计算机代码来执行如权利要求1-6中任一项所述的方法。
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