CN103698022A - Wavefront measurement method of lateral shear interferometer - Google Patents

Abstract

The invention provides a wavefront measurement method of a lateral shear interferometer, and aims at providing a real-time, high-accuracy and rapid method for wavefront distortion measurement of the lateral shear interferometer. The method adopts the following technical scheme that the method comprises the steps that a filtering function set by experience is set as an adaptive algorithm module obtained after automatic analysis and acquisition result computation in lateral shear interferometer measurement software; the adaptive algorithm module makes small-angle inclination and leads in appropriate space carrier frequency by a beam splitter in an interference system; frequency spectrum information and digital weighted filtering are obtained by fourier analysis after imaging system acquisition; light intensity fringe information obtained by a charge coupled device (CCD) is subjected to fourier change and analysis; new frequency spectrum information is obtained; a parameter of the filtering function is automatically computed according to acquired pattern information; a wavefront chart is obtained by filtering, computation and reduction; phase information obtained by filtering is subjected to upwrapping computation and superposition computation; and a final wavefront phase measurement result is obtained.

Description

Lateral shearing interferometer wavefront measurement method

Technical field

The present invention relates to a kind of optical metrology and laser beam metering field of being applied to, the method based on directly applying to lateral shearing interferometer wavefront measurement in shear interference measurement.

Background technology

Radial-shear interferometer is by analyzing, and expands and interference fringe that the two-beam of the bundle that contracts forms in overlapping region after radial-shear interferometer, can obtain the device of the wavefront information of incident light beam to be measured.Because building of radial shear interference light path has diversity, measuring accuracy is high and can select different measuring accuracy according to different tested objects, tested object has popularity, so the detection of wavefront distortion and to control be the important topic that other high power solid state lasers such as ICF laser driver are concerned about always.According to the gaussian random position phase distributed model of scalar diffraction theory and low frequency wave front-distortion, different root mean square gradient LOW FREQUENCY DISTORTION wavefront are larger on the impact of laser beam focal spot focusing, and it will directly exert an influence to the cost of the quality of light beam and laser instrument.The cut mode of wave front shearing interferometer, except transverse radial, also has the mode of rotation and upset shearing.This interferometer is not with reference to corrugated.Lateral shearing interferometer tested light beam resolve into two identical, but traversing coherent light beam mutually.Radial-shear interferometer is that tested light beam is resolved into wavefront figure is similar, but two not identical coherent light beams of xsect size.Interfere and appear in the overlapping region of two coherent light beams.Because lateral shearing interferometer measurement does not have standard corrugated, make tested corrugated change with the corresponding relation of interference fringe not as the interference fringe of other interferometer measurement gained directly perceived like that obviously, thereby use one of key that lateral shearing interferometer measures exactly discrete data sampled point to be carried out to mathematics manipulation, the discrete point that comprises information measured of the extraction from interference wave surface is fitted to a corrugated function approaching as far as possible with actual interference wave surface, shear the matching on corrugated.In asymmetrical distortion corrugated is detected, lateral shearing interferometer (LSI) comes with some shortcomings, most importantly because conoscope image can not directly be given efferent echo difference, need to set filter function by experience, the weak point of this dependence experience setup parameter is to cause bad measurement repeatability, measuring result error range is large, measures the contradiction that wavefront profile and details retain, and measures continuous light or high repetition light time and can not implement to show.Secondly in lateral shearing interference is measured, lateral shearing interferometer device not only needs two lateral shear data on orthogonal directions, and also to from the lateral shear interferograms of mutually orthogonal both direction, extract the phase place of corresponding diaphragm part, calculate the shear interference of X, Y both direction, the difference wavefront that the lateral shear interferograms mutually perpendicular direction obtains can recover two-dimentional wavefront to be measured.In existing two-dimentional wavefront reconstruction algorithm, zernike polynomial matching is the most frequently used a kind of technology.In order to solve in existing Fourier's pattern estimation theory, require shearing displacement to equal the restriction of sampling interval, the problem that the differential phase data dimension that prior art is brought for large shearing displacement reduces, on the basis of Fourier's pattern Expansion Theory, the difference wavefront obtaining from lateral shearing interference, the Fourier Transform Coefficients that calculates wavefront to be measured by least square fitting, reconstructs original wavefront.Because lateral shearing interferometer does not have standard corrugated, between corrugated to be measured and interference fringe, there is no direct corresponding relation, so lateral shearing interference wavefront measurement must be divided into, and acquisition shearing corrugated distributes and reconstruction original wavefront two steps.In reconstruction algorithm, mainly contain net point method [1], integral method [2], the method for undetermined coefficients [3] and least square method [4] etc.Net point method precision is higher, but can only be for two dimension shearing, and hardware requirement is higher, has the problem that operand is huge simultaneously; Integral method can be applied to the situation of one dimension or two dimension shearing, but be only applicable to little shearing displacement, interferes; Least square method utilizes optimized algorithm to solve least squares equation group, and precision is under some influence.The application of the Ze Nike method of undetermined coefficients in lateral shearing interference field is to utilize zernike polynomial to carry out matching to shearing phase to obtain shearing phase zernike coefficient, pass through again x, direct transition matrix between y direction shearing phase zernike polynomial coefficient and tested phase place zernike polynomial coefficient, finally tries to achieve the zernike coefficient of tested phase place.But, one side is due to the complicacy of zernike polynomial itself, between coefficient directly transition matrix solve abnormal difficultly, the application of this method in two-dimensional transversal shear interference field is only confined to the detection of low order phase place (being generally front 35 rank Ze Nike aberrations), be difficult to promote.Radial shear interference system mainly comprises galilean telescope system, three dull and stereotyped shear interference systems, imaging system and collimating and beam expanding system.Radial-shear interferometer mainly comprises the beam splitter 1 shown in Fig. 2, the galilean telescope system that balsaming lens 2 and negative lens 3 form, the first plane mirror 4, the second plane mirror 5, the first catoptron 6, and the imaging system that forms of thick lens 7, the first meniscus lens 8, the second meniscus lens 9, plano-concave lens 10, the second catoptron 11.

1. the at present main reconstruction algorithm of algorithm distorted wavefront and the algorithm of least square fitting are to utilize to interfere

Beam splitter in system is done small angle inclination, introduces suitable space carrier frequency f _xand f _yrear light intensity expression is:

$I(\frac{r}{s},\mathrm{\φ})=a(\frac{r}{s},\mathrm{\φ})+b(\frac{r}{s},\mathrm{\φ})\cos \{{2\mathrm{\πrf}}_x\cos \mathrm{\φ}+{2\mathrm{\πrf}}_y\sin \mathrm{\φ}+{\mathrm{kW}}_{\mathrm{opd}}(\frac{r}{s},\mathrm{\φ})\}---\left(1\right)$

for bias light and modulation of fringes, before φ is incident light wave, k is wave number,

represent before the shearing wave of overlay region, reciprocal square of s is exactly the radial shear enlargement factor of interference system.Bias light and modulation of fringes, turn to formula (1) under rectangular coordinate system and obtain:

δ wherein _sys(x, y) represents the margin of error that optical system part itself is introduced corrugated to be measured, here order

$c(x,y)=\frac{1}{2}b(x,y)\exp [{\mathrm{ikW}}_{o\mathrm{pd}}(x,y)+{\mathrm{i\δ}}_{\mathrm{sys}}(x,y)]---\left(3\right)$

Formula (3) can turn to formula (4), formula (4) is carried out to Fourier transform and obtain its spectrum distribution formula (5).

$\begin{array}{c}I(x,y)=a(x,y)+c(x,y)\exp \left({i2\mathrm{\πf}}_{x}x\right)\exp \left({i2\mathrm{\πf}}_{y}y\right)\\ +c^{*}(x,y)\exp (-{i2\mathrm{\πf}}_{x}x)\exp (-{i2\mathrm{\πf}}_{y}y)\end{array}---\left(4\right)$

I(F _x,F _y)＝A(F _x,F _y)+C(F _x-f _x,F _y-f _y)+C ^*(F _x+f _x,F _y+f _y) （5）

I (F wherein _x, F _y), A (F _x, F _y), C (F _x-f _x, F _y-f _y) and C ^*(F _x+ f _x, F _y+ f _y) the respectively corresponding every Fourier transform of formula (4).At frequency domain by the fundamental frequency C (F that comprises phasic difference signal to be measured and systematic error _x-f _x, F _y-f _y) by a Hanning window function

$\begin{array}{cc}\mathrm{Hann}\left(L\right)=0.5[1-\cos \left(2\mathrm{\π}\frac{n}{L-1}\right)],& 0\≤n\≤L-1\end{array}$

Carry out numerical weighted filtering, φ (x, y) is unpacked and just can obtain shearing corrugated W _opd(x, y).

$\mathrm{\φ}(x,y)={\mathrm{kW}}_{\mathrm{opd}}(x,y)+{\mathrm{\δ}}_{\mathrm{sys}}(x,y)=\arctan \left\{\frac{\mathrm{Im}\left[c(x,y)\right]}{\mathrm{Re}\left[c(x,y)\right]}\right\}$

By superposition calculation, can obtain

$\underset{i=0}{\overset{n}{\mathrm{\Σ}}}{W}_{\mathrm{opd}}(s^{2i-1}r,\mathrm{\φ})=W(\frac{r}{s},\mathrm{\φ})-W(s^{2n+1},\mathrm{\φ}),i=\mathrm{0,1,2,3}\·\·\·n$

N is positive integer, i.e. accumulative frequency.W(s ²ⁿ⁺¹, the wavefront to be measured that φ) expression is amplified, when n is enough large, this will be exaggerated into plane wave front, therefore this can be considered constant and is ignored, the wavefront that obtains finally need to trying to achieve distributes

$\begin{array}{cc}\underset{i=0}{\overset{n}{\mathrm{\Σ}}}{W}_{\mathrm{opd}}(s^{2i-1}r,\mathrm{\φ})=W(\frac{r}{s},\mathrm{\φ}),& i=\mathrm{0,1,2,3}\·\·\·n\end{array}$

Wherein s is contracting bundle multiplying power, and φ is phase place, and i is iterations, and r is spot radius, cannot provide rational Hanning window function parameter L value at present in the method for using.

Summary of the invention

In order better to measure the parameter L value of transient state, pulse laser wavefront and the most rational Hanning window function, the present invention is directed to above-mentioned the deficiencies in the prior art part, provide a kind of real-time, quick, have compared with high measurement accuracy and wave front recovering ability, by adaptive algorithm, measure, can be used for the method that lateral shearing interferometer is measured wavefront distortion.

Above-mentioned purpose of the present invention can reach by following measures, a kind of lateral shearing interferometer wavefront measurement method, it is characterized in that comprising the steps: in lateral shearing interferometer Survey Software, the filter function of originally setting by experience is set to calculate the rear adaptive algorithm module obtaining by automatic analysis collection result, adaptive algorithm module is done small angle inclination by the beam splitter 1 in interference system and is introduced suitable space carrier frequency, until photometry by the two-way of beam splitter 1 transmission and reflection through expanding and the bundle that contracts after the interference fringe that formed, be imaged onto charge-coupled device CCD, after being imaged system acquisition, carry out Fourier analysis and obtain spectrum information and numerical weighted filtering, and the light intensity stripe information that charge-coupled device CCD is obtained is carried out Fourier variation, to the detection striped I (x obtaining, y) do Fourier analysis, obtain spectrum domain and frequency-domain information, then by frequency-domain information automatic acquisition filtering parameter maximal value, minimum value and step-length, automatically set Hanning window function parameter L value and carry out filtering calculating, calculate different Hanning window function parameter L _nthe wavefront distribution results W (L obtaining in situation _n), and wavefront is distributed and does respectively fast discrete Fourier conversion, obtain new spectrum information, adjacent spectrum information is done to correlation computations simultaneously, according to the pattern obtaining, automatically calculate Hanning window function parameter maximal value, minimum value and calculating step-length, get correlation computations result maximal value and the minimum value of result conversion around as final filter function parameter, according to the parameter of the automatic calculation of filtered function of drawing information gathering, from filtered value, carry out contrary Fourier and change acquisition phase information, carry out filtering calculating reduction and obtain wave front chart, the phase information again filtering being obtained unpacks to be calculated and superposition calculation, thereby obtain final Wave-front phase measurement result.

The present invention has following beneficial effect than prior art.

The present invention has carried out novelty design on the basis of using for reference lateral shearing interferometer measuring principle: the filter function of originally setting by experience is changed into by automatic analysis collection result and calculates rear acquisition, according to the parameter of the automatic calculation of filtered function of drawing information gathering, reasonably elimination base-band information and noise, retain suitable wavefront profile and details, improved measuring accuracy.Solved the bad measurement repeatability that relies on experience setup parameter to cause, the error range of measurement result changes greatly, measures the contradiction that wavefront profile and details retain.The selection of original filter function parameter, from manually changing into automatically, has been overcome to the problem that continuous light or high repetition light time can not implement demonstration of measuring.

The present invention utilizes adaptive algorithm to calculate fast lateral shearing interferometer measurement result, by the beam splitter in interference system, do small angle inclination and introduce suitable space carrier frequency, two-way through expanding and contract bundle after formed interference fringe and be imaged system acquisition, collection striped is carried out to Fourier analysis and obtain spectrum information, recycling adaptive algorithm is obtained the parameter of rational filter function and is calculated, filtered value is carried out to contrary Fourier and change acquisition phase information, to carrying out superposition calculation after phase unwrapping, obtain Wave-front phase information, use the rational elimination of filter function and gathered base-band information and the noise in the frequency field of image, suitable wavefront profile and details have been retained, improve measuring accuracy.

Setting parameter in the whole computation process of the present invention can be different according to spectroscopical angle, can automatically mate calculating.The spectrum results calculating has been carried out to correlation computations, and according to the result of relevant clearing, obtained the optimal value of parameter.By use of the present invention, will make radial-shear interferometer be issued to full accuracy in the situation of measuring various wavefront light beams.By theoretical numerical simulation and test findings, all shown that use of the present invention can improve the measurement result of radial-shear interferometer.Import wavefront as Fig. 2, by obtaining stripe information after the bundle that expands, contracts, the spectrum information that obtains of taking the logarithm after stretching, the result of calculation of having utilized wavefront to distribute is carried out spectrum analysis, the wave front chart obtaining by the reduction of self-adaptation Hanning window function parameter method.By repeatedly calculating and can find the correlation computations parameter r in formula 7 _nand the relation between Wavefront detecting root-mean-square value (RMS), this can prove the r proposing in this method _nthe result that larger measuring error is less.The precision of theoretical numerical value proof of analog result this method of the light beam by the different wavefront of substitution, caliber size.By result, can know, in various incident wavefront situations, in the error relativity table of this method adaptive algorithm and general algorithm, adopt the fixedly measuring error PV(wavefront peak-to-peak value obtaining of filter function method) substantially can significantly reduce, and error is relatively stable, less with value and the distortion form relation of incident light wave front-distortion; Measuring error RMS(root-mean-square value) can compare conventional method and reduce, as shown in following contrast.

Original value	Conventional method error	This method error
			PV RMS	PV error RMS error	PV error RMS error
0.05λ0.01λ	10.3%2.5%	2.642%1.426%
			0.08λ0.02λ	4.34%5.9%	0.107%0.255%
0.1λ0.03λ	8.72%7.4%	3.675%4.577%
			0.15λ0.04λ	3.88%2.75%	1.001%0.229%
0.19λ0.06λ	2.46%4.17%	0.090%1.406%
			0.29λ0.07λ	3.9%4.00%	0.821%1.322%
0.36λ0.09λ	3.98%6.37%	1.907%2.187%

Accompanying drawing explanation

Fig. 1 is the process flow diagram of lateral shearing interferometer wavefront measurement method of the present invention.

Fig. 2 is the optical path schematic diagram of shearing interferometer optical system.

In figure: 1 beam splitter, 2 balsaming lenss, 3 negative lenses, 4 plane mirrors, 5 plane mirrors, 6 catoptrons, 7 thick lenses, 8 meniscus lens, 9 meniscus lens, 10 plano-concave lenss, 11 catoptrons.

Embodiment

As shown in Figure 1, in a most preferred embodiment of a kind of lateral shearing interferometer wavefront measurement method described below, lateral shearing interferometer wavefront measurement comprises the adaptive algorithm module being arranged in lateral shearing interferometer Survey Software, the light intensity stripe information that adaptive algorithm module is obtained by charge-coupled device CCD is carried out Fourier and is changed acquisition frequency-domain information, by frequency-domain information automatic acquisition filtering parameter maximal value, after minimum value and step-length, carry out filtering calculating, information after each parametric filtering is carried out to Fourier transform and obtain new spectrum information, adjacent spectrum information is carried out to correlation computations, get the most final filtering parameter of the peaked parameter of correlation computations and carry out filtering calculating, the phase information that filtering is obtained unpacks calculating, after superposition calculation, obtain final Wave-front phase measurement result.First, adaptive algorithm module is done Fourier analysis to the detection striped I (x, y) obtaining, and obtains spectrum domain and is:

I(F _x,F _y)＝A(F _x,F _y)+C(F _x-f _x,F _y-f _y)+C ^*(F _x+f _x,F _y+f _y) (5)

A (F wherein _x, F _y) be zero level frequency spectrum, C (F _x-f _x, F _y-f _y) be positive one-level frequency spectrum, C ^*(F _x-f _x, F _y-f _y) be the conjugation of negative one-level frequency spectrum.On spectrum domain, calculate positive one-level frequency spectrum C (F _x-f _x, F _y-f _y) peak value to center spectrum A (F _x, F _y) distance of peak value is x _d, at this moment get Hanning window function parameter L _min=x _d, get positive one-level frequency spectrum C (F _x-f _x, F _y-f _y) peak value three dB bandwidth x _s, at this moment get L _min=x _s, get respectively L value from L _minto L _max, calculate different parameters L _nthe wavefront distribution results W (L obtaining in situation _n).Adaptive algorithm module distributes and does respectively fast discrete Fourier conversion wavefront,

$\begin{array}{cc}\mathrm{FW}\left(n\right)=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}W\left(k\right)e^{-j(2\mathrm{\π}/N)\mathrm{nk}}& n=0,...,N-1\end{array}$

Obtain result spectrogram FW (L _n), wherein W (k) is wavefront distribution results, k is wave number.Spectrogram is done to logarithm stretching conversion

FWL(L _n)=log[1+FW(L _n)] (6)

Again the spectrogram after stretching conversion being done to Fourier divides and obtains FFWL (L _n), use cross-correlation calculation to obtain,

r _n=max{[FFWL(L _n)]*[FFWL(L _n-1)]} (7)

Get r _nthe L of middle maximal value representative _mfor rational Hanning window function parameter, and obtain in proper order wavefront distribution results

fFWL (L wherein _n) and FFWL (L _n-1)] represent respectively (the L to FWL _n) and FWL (L _n-1) doing Fourier transform, max represents to get maximal value, and * represents to do correlation computations, and n is positive integer.

In carrying out numerical weighted filtering, use adaptive filter algorithm, first by positive one-level spectrum peak, obtain initial parameter, initial parameter is brought into and calculated the rear wavefront distribution that obtains, wavefront is distributed and carries out Fourier transform acquisition spectrogram, spectrogram is carried out to log-transformation, after increasing initial parameter by step-length, obtain spectrogram, do cross-correlation calculation with last spectrogram, get correlation computations maximal value result as true filtering parameter, then the Wave-front phase obtaining is unpacked and just can obtain shearing corrugated, the shearing corrugated obtaining is carried out can obtaining measuring wavefront after superposition calculation processing.

Consult Fig. 2.Radial-shear interferometer mainly comprises that wherein beam splitter 1, balsaming lens 2 and negative lens 3 common optical axis are arranged the galilean telescope system of formation in turn at the beam splitter 1 between the first catoptron 6 and balsaming lens 2 and the negative lens 3 between balsaming lens 2 and the first plane mirror 4.The emergent light of galilean telescope system reflexes to the second plane mirror 5 by first plane mirror 4 that tilts and reflexes to vertically upward beam splitter 1 through the second plane mirror 5.Beam splitter 1 Yi road light splitting by 45 ° of first catoptron 6 by directional light vertical reflection to overlapping successively thick lens 7, the first meniscus lens 8, the second meniscus lens 9, through plano-concave lens 10, project on 45 ° of second catoptron 11 symmetrical with the first catoptron 6, by the second catoptron 11 horizontal reflections to charge-coupled device CCD.Treat that photometry does small angle inclination by the beam splitter 1 in interference system and introduce suitable space carrier frequency, until photometry by the two-way light beam of beam splitter transmission and reflection through expanding and the bundle that contracts after formed interference fringe, and be imaged onto the imaging system that picture on plane the first catoptron 6 formed by lens 7, the first meniscus lens 8, the second meniscus lens 9, plano-concave lens 10 and be imaged onto charge-coupled device CCD.Lateral shearing interferometer software carries out Fourier analysis to collection striped and obtains spectrum information, the parameter that software utilizes adaptive algorithm to obtain rational filter function is calculated, filtered value is carried out to contrary Fourier variation acquisition contracting Shu Guangyu and expand the relative phase information between light, after relative phase is unpacked, carry out superposition calculation and obtain Wave-front phase information.The window parameter L value of the automatic calculation of filtered function of drawing information that adaptive algorithm module gathers according to charge-coupled device CCD.The result of calculation that adaptive algorithm module has utilized wavefront to distribute has been carried out spectrum analysis, pattern is automatically calculated and obtains parameter maximal value, minimum value and calculating step-length by computing formula (5), (6), (7), the spectrum results calculating has been carried out to correlation computations, and according to the result of relevant clearing, obtained the optimal value of Hanning window parameter L.Because spectroscopical angle is different, the effective size of positive 1 grade of frequency spectrum and all can be different apart from the position of fundamental frequency, the Hanning window parameter L in whole computation process can mate its optimal value of calculating automatically according to the result of calculation of formula (5), (6), (7).

CCD(Charge Coupled Device), Chinese name, charge-coupled device, is a kind of special semiconductor material.It by a large number independently light activated element form, these light activated elements normally press that matrix arranges.Light sees through camera lens and is irradiated to CCD above, and is converted into electric charge, and the quantity of electric charge on each element depends on the intensity of illumination that it is suffered.When pressing shutter, CCD is sent to the information of each element on A/D converter, analog electrical signal becomes digital signal after A/D converter is processed, digital signal deposits in buffer memory with certain format boil down to view data, and view data is according to different need to exporting in the mode of digital signal and vision signal.

Hanning window: utilize w=hanning (n) to obtain window function, the length that wherein n is window function, and rreturn value w is the vector on n rank, the n that has comprised a window function coefficient.Filter function is effective wavefront information of extracting in frequency spectrum, elimination noise and fundamental frequency information.

Claims (9)

1. a lateral shearing interferometer wavefront measurement method, it is characterized in that comprising the steps: in lateral shearing interferometer Survey Software, the filter function of originally setting by experience is set to calculate the rear adaptive algorithm module obtaining by automatic analysis collection result, adaptive algorithm module is done small angle inclination by the beam splitter in interference system (1) and is introduced suitable space carrier frequency, until photometry by the two-way of beam splitter (1) transmission and reflection through expanding and the bundle that contracts after the interference fringe that formed, be imaged onto charge-coupled device CCD, after being imaged system acquisition, carry out Fourier analysis and obtain spectrum information and numerical weighted filtering, and the light intensity stripe information that charge-coupled device CCD is obtained is carried out Fourier variation, to the detection striped I (x obtaining, y) do Fourier analysis, obtain spectrum domain and frequency-domain information, then by frequency-domain information automatic acquisition filtering parameter maximal value, minimum value and step-length, automatically set Hanning window function parameter L value and carry out filtering calculating, calculate different Hanning window function parameter L _nthe wavefront distribution results W (L obtaining in situation _n), and wavefront is distributed and does respectively fast discrete Fourier conversion, obtain new spectrum information, adjacent spectrum information is done to correlation computations simultaneously, according to the pattern obtaining, automatically calculate Hanning window function parameter maximal value, minimum value and calculating step-length, get correlation computations result maximal value and the minimum value of result conversion around as final filter function parameter, according to the parameter of the automatic calculation of filtered function of drawing information gathering, from filtered value, carry out contrary Fourier and change acquisition phase information, carry out filtering calculating reduction and obtain wave front chart, the phase information again filtering being obtained unpacks to be calculated and superposition calculation, thereby obtain final Wave-front phase measurement result.

2. lateral shearing interferometer wavefront measurement method as claimed in claim 1, it is characterized in that: in carrying out numerical weighted filtering, first by positive one-level spectrum peak, obtain initial parameter, initial parameter is brought into and calculated the rear wavefront distribution that obtains, wavefront is distributed and carries out Fourier transform acquisition spectrogram, spectrogram is carried out to log-transformation, after increasing initial parameter by single pixel step-length, obtain new spectrogram, do cross-correlation calculation with last spectrogram, get correlation computations maximal value result as true filtering parameter.Then the Wave-front phase obtaining is unpacked and just can obtain shearing corrugated, the shearing corrugated obtaining is carried out can obtaining measuring wavefront after superposition calculation processing.

3. lateral shearing interferometer wavefront measurement method as claimed in claim 1, it is characterized in that: radial-shear interferometer mainly comprise be positioned at the beam splitter (1) between the first catoptron (6) and balsaming lens (2) and be positioned at balsaming lens (2) and the first plane mirror (4) between negative lens (3), wherein beam splitter (1), balsaming lens (2) and negative lens (3) common optical axis are arranged the galilean telescope system of formation in turn.

4. lateral shearing interferometer wavefront measurement method as claimed in claim 3, is characterized in that: the emergent light of galilean telescope system reflexes to the second plane mirror (5) by the first plane mirror (4) that tilts and reflexes to vertically upward beam splitter (1) through the second plane mirror (5).

5. lateral shearing interferometer wavefront measurement method as claimed in claim 1, it is characterized in that: beam splitter (1) Yi road light splitting by 45 ° of first catoptron (6) by directional light vertical reflection to overlapping thick lens (7), the first meniscus lens (8) and the second meniscus lens (9) successively, through plano-concave lens (10), project 45 ° second catoptron (11) symmetrical with the first catoptron (6) upper, by the second catoptron (11) horizontal reflection to electric charge coupling mechanismcCD.

6. lateral shearing interferometer wavefront measurement method as claimed in claim 1, is characterized in that: first, adaptive algorithm module is done Fourier analysis to the detection striped I (x, y) obtaining, and obtains spectrum domain and is:

I(F _x,F _y)＝A(F _x,F _y)+C(F _x-f _x,F _y-f _y)+C ^*(F _x+f _x,F _y+f _y)，

On spectrum domain, calculate positive one-level frequency spectrum C (F _x-f _x, F _y-f _y) peak value to center spectrum A (F _x, F _y) distance of peak value is x _d, at this moment get Hanning window function parameter L _min=x _d, get positive one-level frequency spectrum C (F _x-f _x, F _y-f _y) peak value three dB bandwidth x _s, at this moment get L _min=x _s, get respectively L value from L _minto L _max, calculate different parameters L _nthe wavefront distribution results W (L obtaining in situation _n), wherein, A (F _x, F _y) be zero level frequency spectrum, C (F _x-f _x, F _y-f _y) be positive one-level frequency spectrum, C ^*(F _x-f _x, F _y-f _y) be the conjugation of negative one-level frequency spectrum.

7. lateral shearing interferometer wavefront measurement method as claimed in claim 1, it is characterized in that: in carrying out numerical weighted filtering, use adaptive filter algorithm, first by positive one-level spectrum peak, obtain initial parameter, initial parameter is brought into and calculated the rear wavefront distribution that obtains, wavefront is distributed and carries out Fourier transform acquisition spectrogram, spectrogram is carried out to log-transformation, after increasing initial parameter by step-length, obtain spectrogram, do cross-correlation calculation with last spectrogram, get correlation computations maximal value result as true filtering parameter, then the Wave-front phase obtaining is unpacked and just can obtain shearing corrugated, superposition calculation processing is carried out in the shearing corrugated obtaining and obtain measuring wavefront.

8. lateral shearing interferometer wavefront measurement method as claimed in claim 1, it is characterized in that: lateral shearing interferometer software carries out Fourier analysis to collection striped and obtains spectrum information, the parameter of utilizing adaptive algorithm to obtain rational filter function is calculated, filtered value is carried out to contrary Fourier variation acquisition contracting Shu Guangyu and expand the relative phase information between light, after relative phase is unpacked, carry out superposition calculation and obtain Wave-front phase information.

9. lateral shearing interferometer wavefront measurement method as claimed in claim 1, is characterized in that: the window parameter L value of the automatic calculation of filtered function of drawing information that adaptive algorithm module gathers according to charge-coupled device CCD.

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