CN105387800A - Start point position aligning method for multiwavelength interferometry - Google Patents

Abstract

The invention provides a start point position aligning method for multiwavelength interferometry. Aligning of different wavelength initial positions is realized by combining a provided PZT-driving bow-shaped route drive method and an algorithm, initial phase shift error caused by actual PZT drive inertia is made up, multiwavelength interferometry precision is improved, and measuring repeated precision and reliability are improved; the technical solution adopted in the invention is particularly suitable for the PZT-driving interferometry, can better solve the problem of consistency of the initial position after multiwavelength switching and greatly improves the practical value of the multiwavelength interferometry.

Description

A kind of multi-wavelength interferometry start position alignment schemes

Technical field

The present invention relates to multi-wavelength interferometry field, particularly relate in the phase shift interference of multi-wavelength rotation is measured, PZT phase shift drives and the method for aliging.

Background technology

Microscopic interferometry is one of important method of Surface Microtexture measurement, multi-wavelength interference technology is incorporated in interferometry and effectively can makes up the little deficiency of Single wavelength interferometry scope.The essence of multi-wavelength measuring method is exactly utilize the difference of multi-wavelength measurement result to obtain order of interference, thus obtains the real depth of measured point, reaches the object of expansion depth measurement range.Multi-wavelength interferometry not only can expand depth survey scope, and the measurement result utilizing multi-wavelength measurement result to correct Single wavelength can reduce because measurement range expands the measurement by magnification error caused.

Multi-wavelength interference method often needs to utilize phase-shift method to make interference fringe produce relative deformation, and the relative deformation then by measuring interference fringe completes the measurement of surface profile indirectly.Phase-shift method by with reference to or measure in light and introduce known phase shift amount, the relative phase of people's for a change dry light beam of two-phase, from interference field, the light intensity value of any point under different phase-shift phase solves this phase place.PZT, because having good micrometric displacement characteristic, is commonly used in interferometry the type of drive producing phase shift.But because PZT drives the deficiencies such as linearly poor, inertia is large, cause being difficult to during back and forth movement ensure that initial sum final position remains unchanged.Therefore in multi-wavelength interferometry, when switching between different wave length, the reference position driven due to PZT is inconsistent, will measurement result be caused to there is larger error, thus can not ensure measuring accuracy.

In order to reduce the site error that PZT open loop drives, some drive unit utilizes band metering system to feed back, although this kind of device can ensure the precision being returned to start position to a certain extent, but due in high-precision measuring process, even if very little vibration, for interference magnitude, also can produce larger error, and the measuring accuracy of position metering system self is difficult to reach nanoscale.Therefore, in high-accuracy interferometry, feedback assembly can not ensure the alignment of start position.Meanwhile, owing to being with the closed-loop device of metering system, complex structure, system is installed very difficult.In addition, closed-loop system price is high, causes the cost of final measuring system greatly to improve.

For existing based on there is the problem that when wavelength switches, PZT drives initial position inconsistent in the Microscopic Interferometric Measuring System of multi-wavelength, urgently there is corresponding solution in this area.

Summary of the invention

The object of this invention is to provide a kind of method that multi-wavelength interferometry phase shift drives alignment, the method is on the basis analyzing PZT driving lagging characteristics, adopt the driving PZT in " bow " font path, by applying the reverse drive voltages of half step distance to PZT, to overcome the inertia that PZT drives forwards, and between different wave length during rotation, a kind of driving final position of wavelength is made to be the reference position that lower a kind of wavelength drives, during guarantee wavelength rotation, connecting points position overlaps, calculate total driving phase-shift phase and the initial phase of often kind of wavelength again, then initial sum final position relation is driven according to the phase shift of multi-wavelength, by consistent with the reference position of the first wavelength for moving on to of the start position of other wavelength, realize the alignment of multi-wavelength reference position.

Technical scheme of the present invention is: one is suitable for start position alignment schemes in multi-wavelength interferometry, comprises the following steps;

Step 1, the first wavelength selected, applies driving voltage to PZT and carries out phase shift modulated, if initial driving voltage is V ₀, voltage often increases Δ V ₀, gather a secondary interferogram, until PZT driving voltage reaches capping V ₁after, gather N altogether ₀width figure; Driving voltage is successively decreased and carries out reverse drive, voltage often reduces Δ V ₁gather a width interferogram every, described Δ V ₁be less than Δ V ₀, oppositely stop voltage V until reach ₂, gather N altogether ₁width figure, described V ₂be less than V ₁, N ₁be less than N ₀, then switch to the second wavelength, the driving reference position of the second wavelength overlapped with the driving end position of upper a kind of wavelength, the second wavelength-voltage is converted, from V ₂with step pitch Δ V ₀decay to lower limit V ₃, and meet: V ₁-V ₀=V ₂-V ₃, then from V ₃with step pitch Δ V ₁increase to V ₀, during this period, image acquisition interval and quantity and the first consistent wavelength; When switching the third wavelength, repeating the operation of the first wavelength above, selecting the operation repeating the second wavelength during the 4th kind of wavelength, according to repeating principle above, a to the last wavelength, can be expressed as the light intensity of piece image of appointing of any wavelength:

Wherein, (x, y) is pixel coordinate in interferogram, λ _kfor kth kind wavelength, k=1,2 ... M, i are wavelength X _ktime interferogram sequence number, i=1,2 ... N, and N=N ₀+ N ₁, described M and N is natural number; for direct current light intensity, for exchanging light intensity amplitude, for initial phase, for phase shift drive volume.

Step 2, calculates initial phase corresponding to often kind of wavelength respectively to all interferograms that step 1 obtains with total phase shift drive volume (k=1,2 ... M);

Step 3, utilizes the wavelength X obtained _kin the initial phase of each pixel with total phase shift drive volume calculate the initial phase amount after start position alignment under different wave length

For wavelength 1,

For wavelength 2,

For wavelength k, wherein, the last item of mod function representation is relative to a rear complementation;

Utilize the initial phase after alignment calculate the surface topography height of this point, can measuring accuracy.

Preferably, in described step 1, be the consistance of connecting points position during guarantee rotation wavelength, the driving of PZT adopts arc type type of drive, and before wavelength switches, is overcome the inertia driven forwards by the reverse drive of half step distance.

Preferably, in described step 2, following sub-step is comprised to each pixel initial phase of any one wavelength and the calculating of total phase-shift phase:

Step 2.1, interferes in sequence image at the N width of Same Wavelength, finds the two width figure I that two width phase differential are approximately k π+pi/2+Δ _m, I _n; In each width figure of N width interferogram, choose the region comprising center, account for the total area 1/10th, the light intensity value of pixels all in this region is asked for average, obtain N number of light intensity value, maximum value and minimal value is found again in this N number of light intensity value, utilize maximum value and minimal value to obtain intermediate value, choose maximum value and distinguish corresponding image as I closest to intermediate value _m, I _n;

Step 2.2, the two width interferogram I found _m, I _nin, according to the Changing Pattern of light intensity value in different interferogram of each pixel, find the coordinate figure meeting rule; For image I _min the light intensity I of any point _m(x, y) meets I _m(x, y) < I _m-1time (x, y), by this coordinate figure put stored in coordinate array ArrayP ₁in []; For image I _nin the light intensity I of any point _n(x, y) meets I _n(x, y) < I _n-1time (x, y), by this coordinate figure put stored in coordinate array ArrayP ₂in [], suppose that Two coordinate number is respectively n ₁, n ₂;

Step 2.3, in order to eliminate the impact of single-point stochastic error, carries out gray-scale value average calculating operation to the N width figure of Same Wavelength collection, and obtains two new gray value sequence g ₁(i), g ₂(i):

$\left\{\begin{array}{c}{g}_1\left(i\right)=\frac{1}{n_1}\underset{l=1}{\overset{n_1}{\&Sigma;}}{I}_i(Array{P}_1\&lsqb;l\&rsqb;.x,Array{P}_1\&lsqb;l\&rsqb;\&CenterDot;y)\\ g_2\left(i\right)=\frac{1}{n_2}\underset{p=1}{\overset{n_2}{\&Sigma;}}{I}_i(Array{P}_2\&lsqb;l\&rsqb;.x,Array{P}_2\&lsqb;l\&rsqb;\&CenterDot;y)\end{array}\right.$

Wherein, n ₁, n ₂be respectively coordinate array ArrayP ₁[] and ArrayP ₂coordinate figure number in [], ArrayP ₁[l] .x, ArrayP ₁[l] .y is respectively array ArrayP ₁x, y coordinate figure of l point in [], ArrayP ₂[l] .x, ArrayP ₂[l] .y is respectively array ArrayP ₂x, y coordinate figure of p point in [], i is interferogram sequence number;

Step 2.3, according to two grey-level sequence g ₁(i), g ₂i () calculates total phase value corresponding to the i-th width interferogram

Step 2.4, carries out the computing of solution parcel, obtains the phase shift drive volume of every width interferogram because of initial position following formula is utilized to calculate, during calculating from i=2,

${\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i}=\left\{\begin{array}{cc}{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}& -\mathrm{\&pi;}<{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}<\mathrm{\&pi;}\\ {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+2\mathrm{\&pi;}& {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}<-\mathrm{\&pi;}\\ {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}-2\mathrm{\&pi;}& {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}>\mathrm{\&pi;}\end{array}\right.$

As i=N, can calculate total phase driven amount is

Step 2.5, according to the light intensity sequence of each pixel with phase shift drive volume obtain each pixel initial phase

Wavelength X is obtained according to above step _kcorresponding initial phase with total phase shift drive volume

Preferably, in described step 2.3, according to two grey-level sequence g ₁(i), g ₂i () calculates total phase value corresponding to the i-th width interferogram in conjunction with ellipse fitting algorithm

Preferably, in described step 2.5, according to the light intensity sequence of each pixel with phase shift drive volume sinusoidal signal least square method is utilized to obtain each pixel initial phase

Technique effect of the present invention is: one is suitable for start position alignment schemes in multi-wavelength interferometry, the PZT provided drives the alignment of different wave length reference position of " bow " word path drives methods combining algorithm realization, make up the start-up phase shift error that actual PZT drives inertia to cause, improve multi-wavelength interferometry precision, improve and measure repeatable accuracy and reliability; The technical solution adopted in the present invention is specially adapted to the interferometry utilizing PZT to drive, can better solve multi-wavelength switch after reference position consistency problem, the significant increase practical value of multi-wavelength interferometry.

Accompanying drawing explanation

Fig. 1 is the multi-wavelength interferometry reference position alignment schemes flow process of the embodiment of the present invention;

Fig. 2 is the PZT driving voltage schematic diagram of the embodiment of the present invention;

Fig. 3 is different wave length reference position alignment schematic diagram in the embodiment of the present invention.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with the drawings and specific embodiments, the structure of device of the present invention and measuring principle are described in further detail.

The invention provides the method for reference position alignment in a kind of multi-wavelength interferometry, utilize wavelength to switch head and the tail coincidence method and overcome the reverse drive method that PZT drives inertia, combine the suitable algorithm of design again, achieve the alignment of reference position during multi-wavelength rotation.The present invention can realize the reference position alignment accuracy of different wave length switching within a few nanometer.

Ask for an interview Fig. 1, a kind of multi-wavelength interferometry reference position alignment schemes, comprises the following steps,

Step 1, gathers the interference image of three kinds of wavelength.Fig. 2 is asked for an interview in choosing of PZT driving voltage, drives path to adopt " bow " font, asks for an interview Fig. 3.The first wavelength selected, apply driving voltage to PZT and carry out phase shift modulated, initial driving voltage gets V ₀=3V, voltage often increases Δ V ₀=0.2V, gathers a secondary interferogram, until PZT driving voltage reaches capping V ₁after=9V, gather N altogether ₀=30 width interferograms; Now, in order to overcome the inertia of PZT forward, driving voltage successively decreases and carries out reverse drive, voltage often reduce 0.15V gather a width interferogram every, until oppositely stop voltage V ₂=8.25V, gathers N altogether ₁=5 width figure (N ₁be less than N ₀, be about 1/6), 1. path of walking to be seen in Fig. 3; Then switch to the second wavelength, the driving reference position of the second wavelength is overlapped with the driving end position of upper a kind of wavelength, to the Changing Pattern of the second wavelength-voltage and the similar of the first wavelength, decays to V from 8.25V with step pitch 0.2V ₃=2.25V, and then increase to 3V with step pitch 0.15V from 2.25V, the same with the first wavelength, gather 35 width interferograms altogether, 2. path of walking to be seen in Fig. 3; Switch to the third wavelength again, repeat above operation, 3. path of walking to be seen in Fig. 3.

Can be expressed as the light intensity of piece image of appointing of any wavelength:

Wherein, (x, y) is pixel coordinate in interferogram, λ _kfor kth kind wavelength, k=1,2,3, i are wavelength X _ktime interferogram ordinal number, i=1,2 ... 35, for direct current light intensity, for exchanging light intensity amplitude, for initial phase, for phase shift drive volume.

Step 2, calculates initial phase corresponding to often kind of wavelength respectively to all interferograms that step 1 obtains with total phase shift drive volume (k=1,2,3).Following sub-step is comprised to the calculating of total phase-shift phase of any one wavelength,

Step 2.1, interferes in sequence image at 35 width of Same Wavelength, finds the two width figure I that two width phase differential are approximately k π+pi/2+Δ _m, I _n.In each width figure of 35 width interferograms, choose the region comprising center, account for the total area 1/10th, the light intensity value of pixels all in this region is asked for average, obtain 35 light intensity values, maximum value and minimal value is found again in these 35 light intensity values, utilize maximum value and minimal value to obtain intermediate value, choose maximum value and distinguish corresponding image as I closest to intermediate value _m, I _n.

Step 2.2, the two width interferogram I found _m, I _nin, according to the Changing Pattern of light intensity value in different interferogram of each pixel, find the coordinate figure meeting rule.For image I _min the light intensity I of any point _m(x, y) meets I _m(x, y) < I _m-1time (x, y), by this coordinate figure put stored in coordinate array ArrayP ₁in []; For image I _nin the light intensity I of any point _n(x, y) meets I _n(x, y) < I _n-1time (x, y), by this coordinate figure put stored in coordinate array ArrayP ₂in [], suppose that Two coordinate number is respectively n ₁, n ₂.

Step 2.3, in order to eliminate the impact of single-point stochastic error, carries out gray-scale value average calculating operation to the N width figure of Same Wavelength collection, and obtains two new gray value sequence g ₁(i), g ₂(i):

$\left\{\begin{array}{c}{g}_1\left(i\right)=\frac{1}{n_1}\underset{l=1}{\overset{n_1}{\&Sigma;}}{I}_i(Array{P}_1\&lsqb;l\&rsqb;.x,Array{P}_1\&lsqb;l\&rsqb;.y)\\ g_2\left(i\right)=\frac{1}{n_2}\underset{p=1}{\overset{n_2}{\&Sigma;}}{I}_i(Array{P}_2\&lsqb;l\&rsqb;.x,Array{P}_2\&lsqb;l\&rsqb;.y)\end{array}\right.$

Wherein, n ₁, n ₂be respectively coordinate array ArrayP ₁[] and ArrayP ₂coordinate figure number in [], ArrayP ₁[l] .x, ArrayP ₁[l] .y is respectively ArrayP in array ₁x, y coordinate figure of [] l point, ArrayP ₂[l] .x, ArrayP ₂[l] .y is respectively ArrayP in array ₂x, y coordinate figure of [] p point, i is interferogram sequence number.

Step 2.3, according to two grey-level sequence g ₁(i), g ₂i (), in conjunction with ellipse fitting algorithm, calculates total phase value that the i-th width interferogram is corresponding

Step 2.4, carries out the computing of solution parcel, obtains the phase shift drive volume of every width interferogram because of initial position =0, utilize following formula to calculate, during calculating from i=2,

${\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i}=\left\{\begin{array}{cc}{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}& -\mathrm{\&pi;}<{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}<\mathrm{\&pi;}\\ {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+2\mathrm{\&pi;}& {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}<-\mathrm{\&pi;}\\ {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}-2\mathrm{\&pi;}& {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}>\mathrm{\&pi;}\end{array}\right.$

As i=N, can calculate total phase driven amount is

Step 2.5, according to the light intensity sequence of each pixel with phase shift drive volume sinusoidal signal least square method is utilized to obtain each pixel initial phase

Wavelength X is obtained according to above step _kcorresponding initial phase with total phase shift drive volume

Step 3, utilizes the wavelength X obtained _kin the initial phase of each pixel with total phase shift drive volume calculate the initial phase amount after start position alignment under different wave length

For wavelength 1,

For wavelength 2,

For wavelength 3,

Wherein, the last item of mod function representation is relative to a rear complementation.

Utilize the initial phase after alignment calculate the surface topography height of this point, while increase measurement range, measuring accuracy can be ensured.

Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various amendment or supplement or adopt similar mode to substitute to described specific embodiment, driving voltage and the acquisition interval voltage of such as PZT can be set voluntarily as the case may be by those skilled in the art, but can't depart from spirit of the present invention or surmount the scope that appended claims defines.

Claims (5)

1. be suitable for a start position alignment schemes in multi-wavelength interferometry, it is characterized in that, comprise the following steps:

Step 1, the first wavelength selected, applies driving voltage to PZT and carries out phase shift modulated, if initial driving voltage is V ₀, voltage often increases Δ V ₀, gather a secondary interferogram, until PZT driving voltage reaches capping V ₁after, gather N altogether ₀width figure; Driving voltage is successively decreased and carries out reverse drive, voltage often reduces Δ V ₁gather a width interferogram every, described Δ V ₁be less than Δ V ₀, oppositely stop voltage V until reach ₂, gather N altogether ₁width figure, described V ₂be less than V ₁, N ₁be less than N ₀, then switch to the second wavelength, the driving reference position of the second wavelength overlapped with the driving end position of upper a kind of wavelength, the second wavelength-voltage is converted, from V ₂with step pitch Δ V ₀decay to lower limit V ₃, and meet: V ₁-V ₀=V ₂-V ₃, then from V ₃with step pitch Δ V ₁increase to V ₀, during this period, image acquisition interval and quantity and the first consistent wavelength; When switching the third wavelength, repeating the operation of the first wavelength above, selecting the operation repeating the second wavelength during the 4th kind of wavelength, according to repeating principle above, a to the last wavelength, can be expressed as the light intensity of piece image of appointing of any wavelength:

Wherein, (x, y) is pixel coordinate in interferogram, λ _kfor kth kind wavelength, k=1,2 ... M, i are wavelength X _ktime interferogram sequence number, i=1,2 ... N, and N=N ₀+ N ₁, described M and N is natural number; for direct current light intensity, for exchanging light intensity amplitude, for initial phase, for phase shift drive volume;

Step 2, calculates initial phase corresponding to often kind of wavelength respectively to all interferograms that step 1 obtains with total phase shift drive volume

Step 3, utilizes the wavelength X obtained _kin the initial phase of each pixel with total phase shift drive volume calculate the initial phase amount after start position alignment under different wave length

For wavelength 1,

For wavelength 2,

For wavelength k,

Wherein, the last item of mod function representation is relative to a rear complementation;

Utilize the initial phase after alignment calculate the surface topography height of this point, can measuring accuracy.

2. one according to claim 1 is suitable for start position alignment schemes in multi-wavelength interferometry, it is characterized in that, in described step 1, for the consistance of connecting points position during guarantee rotation wavelength, the driving of PZT adopts arc type type of drive, and before wavelength switches, overcome the inertia driven forwards by the reverse drive of half step distance.

3. one according to claim 1 is suitable for start position alignment schemes in multi-wavelength interferometry, it is characterized in that, in described step 2, comprises following sub-step to each pixel initial phase of any one wavelength and the calculating of total phase-shift phase:

Step 2.1, interferes in sequence image at the N width of Same Wavelength, finds the two width figure I that two width phase differential are approximately k π+pi/2+Δ _m, I _n; In each width figure of N width interferogram, choose the region comprising center, account for the total area 1/10th, the light intensity value of pixels all in this region is asked for average, obtain N number of light intensity value, maximum value and minimal value is found again in this N number of light intensity value, utilize maximum value and minimal value to obtain intermediate value, choose maximum value and distinguish corresponding image as I closest to intermediate value _m, I _n;

Step 2.2, the two width interferogram I found _m, I _nin, according to the Changing Pattern of light intensity value in different interferogram of each pixel, find the coordinate figure meeting rule; For image I _min the light intensity I of any point _m(x, y) meets I _m(x, y) < I _m-1time (x, y), by this coordinate figure put stored in coordinate array ArrayP ₁in []; For image I _nin the light intensity I of any point _n(x, y) meets I _n(x, y) < I _n-1time (x, y), by this coordinate figure put stored in coordinate array ArrayP ₂in [], suppose that Two coordinate number is respectively n ₁, n ₂;

Step 2.3, in order to eliminate the impact of single-point stochastic error, carries out gray-scale value average calculating operation to the N width figure of Same Wavelength collection, and obtains two new gray value sequence g ₁(i), g ₂(i):

$\left\{\begin{array}{c}{g}_1\left(i\right)=\frac{1}{n_1}\underset{l=1}{\overset{n_1}{\&Sigma;}}{I}_i({\mathrm{ArrayP}}_1\&lsqb;l\&rsqb;.x,{\mathrm{ArrayP}}_1\&lsqb;l\&rsqb;.y)\\ g_2\left(i\right)=\frac{1}{n_2}\underset{p=1}{\overset{n_2}{\&Sigma;}}{I}_i({\mathrm{ArrayP}}_2\&lsqb;l\&rsqb;.x,{\mathrm{ArrayP}}_2\&lsqb;l\&rsqb;.y)\end{array}\right.$

Wherein, n ₁, n ₂be respectively coordinate array ArrayP ₁[] and ArrayP ₂coordinate figure number in [], ArrayP ₁[l] .x, ArrayP ₁[l] .y is respectively array ArrayP ₁x, y coordinate figure of l point in [], ArrayP ₂[l] .x, ArrayP ₂[l] .y is respectively array ArrayP ₂x, y coordinate figure of p point in [], i is interferogram sequence number;

Step 2.3, according to two grey-level sequence g ₁(i), g ₂i () calculates total phase value corresponding to the i-th width interferogram

Step 2.4, carries out the computing of solution parcel, obtains the phase shift drive volume of every width interferogram because of initial position following formula is utilized to calculate, during calculating from i=2,

${\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i}=\left\{\begin{array}{cc}{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}& -\mathrm{\&pi;}<{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}<\mathrm{\&pi;}\\ {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+2\mathrm{\&pi;}& {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}<-\mathrm{\&pi;}\\ {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}+{\mathrm{\&theta;}}_{{\mathrm{\&lambda;}}_{k}i-1}-2\mathrm{\&pi;}& {\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i}-{\mathrm{\&Delta;}}_{{\mathrm{\&lambda;}}_{k}i-1}>\mathrm{\&pi;}\end{array}\right.$

As i=N, can calculate total phase driven amount is

Step 2.5, according to the light intensity sequence of each pixel with phase shift drive volume obtain each pixel initial phase

Wavelength X is obtained according to above step _kcorresponding initial phase with total phase shift drive volume

4. one according to claim 3 is suitable for start position alignment schemes in multi-wavelength interferometry, it is characterized in that, in described step 2.3, according to two grey-level sequence g ₁(i), g ₂i () calculates total phase value corresponding to the i-th width interferogram in conjunction with ellipse fitting algorithm

5. one according to claim 3 is suitable for start position alignment schemes in multi-wavelength interferometry, it is characterized in that, in described step 2.5, according to the light intensity sequence of each pixel with phase shift drive volume sinusoidal signal least square method is utilized to obtain each pixel initial phase