CN104655290A - Fizeau dual-wavelength laser tuning phase-shifting interference testing device and testing method thereof - Google Patents

Abstract

The invention discloses a Fizeau dual-wavelength laser tuning phase-shifting interference testing device and a testing method and relates to the field of light interference testing. The method comprises the steps of employing two tunable lasers with different central wavelengths as light sources for simultaneous operation in a Fizeau interference testing light path, achieving interference phase shifting via wavelength tuning, after light splitting by a dichroscope, calibrating phase-shifting stepping amount with phase-shifting interferograms acquired by a detector under the two wavelengths to ensure that the phase-shifting stepping amount under the two wavelengths are pi/2 and -pi/2 respectively, carrying out phase shifting on the two tunable lasers as the light sources according to the calibrated phase-shifting stepping amount, acquiring a moire fringe interferogram formed by superposition of two paths of interference light with the detector, and carrying out a dual-wavelength phase-shifting interference algorithm on the phase-shifting moire fringe interferogram acquired by the detector to obtain tested phase information, wherein the interferogram comprises phase information of synthesis wavelength. The device and the method can extend a surface scope of interferometry, and an interferogram processing algorithm is simple.

Description

The tuning movable phase interfere proving installation of striking rope type dual-wavelength laser and method of testing thereof

Technical field

The present invention relates to interference of light field tests, particularly the tuning movable phase interfere proving installation of a kind of striking rope type dual-wavelength laser and method thereof.

Background technology

Striking rope type interferometer is a kind of thicker interferometer such as conventional, there is the feature of reference light and the common light path of test light, may be used for plane, sphere and aspheric surface shape measurement, the measurement of the corrugated transmission quality of the measurement of sphere curvature radius and various lens, prism, optical system.

Movable phase interfere is a kind of precision optics interfere measurement technique, adopt accurate phase shifting device in reference path, introduce specific phase shift value in an orderly manner, the phase differential changing reference light and test light realizes phase-modulation, detector (as CCD) is utilized to gather digitized interferogram, accurately calculated the corrugated information comprised in interferogram by different corrugated derivation algorithms, measuring accuracy can reach 1/50 wavelength.Common phase-moving method has piezoelectric ceramics (PZT) phase shift, rotatory polarization device (wave plate, polaroid) phase shift, mobile diffraction grating or tilt flat plate phase shift, wavelength phase shift etc.

Phase-shifting interferometer normally adopts single wavelength as light source, have higher measuring accuracy and good measuring repeatability, but its measurement range is less, is applicable to the noncontinuous surface that continuous surface and bench height are less than 0.5 wavelength.In the surface testing process of step surface, tested step difference of height is comparatively large, causes the phase differential of neighbor to be greater than π and exceedes its measurement range, correctly cannot recover the height of step.

In order to expand the test specification of Single wavelength phase-shifting interferometer, the people such as Yeou-Yen Cheng are at " Two-wavelength phase shifting interferometry " (APPLIED OPTICS, 24 (23): 4539-4543,1984) dual wavelength movable phase interfere method of testing is proposed in, utilize synthetic wavelength technology to carry out the larger face shape of metrical error, solve the 2 π fuzzy problems that traditional Single wavelength interference testing occurs.For the error enlarge-effect of synthetic wavelength phase place, the people such as Yeou-Yen Cheng are subsequently at its " Multiple-wavelengthphase-shifting interferometry " (APPLIED OPTICS, 24 (6): 804-807,1985) propose in a literary composition with synthetic wavelength phase data correction Single wavelength phase data, under the prerequisite of bonding wavelength movable phase interfere measuring accuracy, expand the measurement range of Single wavelength shift-phase interferometry.Traditional dual wavelength movable phase interfere proving installation generally adopts piezoelectric ceramics (PZT) phase shift, and the method deposits PZT Phase-shifting Errors at different wavelengths.For the Phase-shifting Errors problem under different wave length, Joanna Schmit is at " Two-wavelength interferometricprofilometry with a phase-step error-compensating algorithm " (OpticalEngineering, 45 (11): 115602_1-115602_3, 2006) for the PZT phase shift calibration error problem under two kinds of wavelength in dual wavelength movable phase interfere test process in, proposition employing solves the phase value under two kinds of wavelength to the insensitive 8 step Phase-shifting algorithm of phase shift calibration error, but computation process is complicated and the compensation of its Phase-shifting Errors exists certain scope.In order to solve dual wavelength Phase-shifting Errors problem from hardware aspect, Michael B.North-Morris is at " Phase-Shifting Multi-Wavelength Dynamic Interferometer " (Proceedings of SPIE, Vol.5531:64-75, Bellingham, WA, 2004) a kind of dual wavelength dynamic interference pick-up unit is devised), the phase mask directly placing Pixel-level before CCD realizes simultaneous phase-shifting, by carrying out the simultaneous phase-shifting that achromat-design realizes under different wave length to mask plate, but it is very high to the design processing request of mask plate, structure installment is complicated and follow-up process is loaded down with trivial details.Youichi Bitou is at " Two-wavelength phase-shiftinginterferometry using an electrically addressed liquid crystal spatial light modulator " (APPLIED OPTICS, 44 (9): 1577-1581, 2005) a kind of dual wavelength interference testing device based on spatial light modulator (EA-SLM) phase shift is devised in, rightabout accurate unique step phase shift under achieving two kinds of wavelength, adopt tradition phase-shifting algorithm extracting directly synthetic wavelength phase data, but its device is because comprising a large amount of polarizer and diffraction element, and structure seems complicated.D.G.Abdelsalam is at " Two-wavelength in-linephase-shifting interferometry based on polarizing separation for accurate surfaceprofiling " (APPLIED OPTICS, 55 (33): 6153-6161, 2011) two-wavelength-interferometer proposed in adopts polarization spectro light path design, based on Mach Zehnder optical interference circuit structure, the PZT of closed-loop control is adopted to realize the accurate phase shift under two kinds of wavelength, resolution is 1nm, solve phase shift calibration error problem under different wave length, but it is high and expensive to the requirement of PZT.The people such as Tian Ailing describe a kind of dual wavelength movable phase interfere proving installation in its patent " a kind of surface shape detection apparatus of large scale and high accuracy and detection method thereof " (application number 201310044110.3), the frequency-converted solid state laser adopting tunable range to be greater than 30nm realizes wavelength movable phase interfere two central wavelength respectively, obtain phase-shift interference respectively, to be multiplied superposition interferogram based on Moire fringe theory, in frequency domain, low-pass filtering obtains the interference light intensity figure comprising synthetic wavelength phase place, finally adopts Phase-shifting algorithm to extract synthetic wavelength phase place.Due to employing is that a frequency-converted solid state laser realizes wavelength movable phase interfere respectively two central wavelength, and therefore this Measures compare is consuming time.In addition, this device needs to carry out frequency spectrum low-pass filtering treatment to the interference light intensity figure of superposition, and the selection of wave filter can reduce the precision of test data, and complex disposal process.

Summary of the invention

The object of this invention is to provide the tuning movable phase interfere proving installation of a kind of striking rope type dual-wavelength laser and method thereof, quick and precisely can extract the digital corrugated proving installation of the large scale and high accuracy of synthetic wavelength phase place, adopt to expand the measurement range of Single wavelength interference testing device and traditional double phase-shifting interferometer via wavelength tuning the Phase-shifting Errors problem can introduced during PZT phase shift under different wave length.

The technical solution realizing the object of the invention is: it is λ that the tuning movable phase interfere proving installation of a kind of striking rope type dual-wavelength laser comprises centre wavelength ₁tunable laser, the first beam expanding lens, the first Amici prism, standard mirror, measured lens, centre wavelength be λ ₁tunable laser, the second beam expanding lens, the second Amici prism, the first spectroscope, the first imaging len, the first ccd detector, the second imaging len, the second ccd detector, the 3rd imaging len, the 3rd ccd detector and cutoff wavelength be λ ₃dichroic mirror, wherein λ ₁≠ λ ₂, min (λ ₁, λ ₂) < λ ₃<max (λ ₁, λ ₂); Setting gradually centre wavelength is λ ₁tunable laser, the first beam expanding lens and the first Amici prism, the optical axis at their places is primary optic axis; Set gradually the second Amici prism, the first spectroscope, cutoff wavelength be λ ₃dichroic mirror, the 3rd imaging len and the 3rd ccd detector, the optical axis at their places is the second optical axis; Setting gradually centre wavelength is λ ₂tunable laser, the second beam expanding lens, the second Amici prism, the first Amici prism, standard mirror and measured lens, the optical axis at their places is the 3rd optical axis; Set gradually the first spectroscope, the first imaging len and the first ccd detector, the optical axis at their places is the 4th optical axis; Setting gradually cutoff wavelength is λ ₃dichroic mirror, the second imaging len and the second ccd detector, the optical axis at their places is the 5th optical axis, primary optic axis and the second optical axis are vertical with the 3rd optical axis respectively, 4th optical axis is vertical with the second optical axis respectively with the 5th optical axis, second optical axis included angle of the first spectroscope and vertical direction is 45 °, and cutoff wavelength is the dichroic mirror of λ and the second optical axis included angle of vertical direction is 135 °; Be λ by centre wavelength ₁the wavelength that sends of tunable laser be λ ₁laser after the first beam expanding lens beam-expanding collimation, become the heavy caliber parallel beam of collimation, this parallel beam reflexes to standard mirror and measured lens through the first Amici prism, and defining wavelength is λ ₁laser tuning movable phase interfere optical system for testing; Be λ by centre wavelength ₂the wavelength that sends of tunable laser be λ ₂laser after the second beam expanding lens beam-expanding collimation, become the heavy caliber parallel beam of collimation, this parallel beam is incident to standard mirror and measured lens through the second Amici prism and the first Amici prism, and defining wavelength is λ ₂laser tuning movable phase interfere optical system for testing; The wavelength being incident to standard mirror and measured lens is λ ₁and λ ₂light wave through standard mirror and measured lens back reflection, the first spectroscope is reflexed to by the second Amici prism through after the first Amici prism, two bundles are divided into after the first spectroscope, a branch of is the first reflected light, another bundle is the first transmitted light, the first reflected light finally by the first imaging len gather by the first ccd detector and define λ ₁and λ ₂moire fringe phase-shift interference after interference light superposition gathers light path, and the first transmitted light is λ through being incident to cutoff wavelength after the first spectroscope ₃dichroic mirror, the first transmitted light is λ through cutoff wavelength ₃dichroic mirror after be divided into two bundles, a branch of wavelength is λ ₂the second reflected light, another bundle for wavelength be λ ₁the second transmitted light, the second reflected light through the second imaging len finally by second ccd detector collection formed realize λ ₂the signals collecting light path of accurate phase shifting control, the second transmitted light is finally formed by the 3rd ccd detector collection through the 3rd imaging len and realizes λ ₁the signals collecting light path of accurate phase shifting control.

The above-mentioned tuning movable phase interfere proving installation of striking rope type dual-wavelength laser, its feature is to work as λ ₁﹤ λ ₃﹤ λ ₂, dichroic mirror is low pass dichroic mirror, is namely less than cutoff wavelength λ ₃λ ₁light wave can be greater than cutoff wavelength λ through dichroic mirror ₃λ ₂light wave can by dichroic mirror reflects.Work as λ ₂﹤ λ ₃﹤ λ ₁, dichroic mirror is high pass dichroic mirror, is namely greater than cutoff wavelength λ ₃λ ₁light wave can be less than cutoff wavelength λ through dichroic mirror ₃λ ₁light wave can by dichroic mirror reflects.The tuning movable phase interfere proving installation of striking rope type dual-wavelength laser adopts centre wavelength to be λ ₁tunable laser and λ ₂tunable laser according to λ ₁and λ ₂the phase shift stepping-in amount being respectively pi/2 and-pi/2 carries out wavelength phase shift, synchronously carries out the detection of wavelength movable phase interfere to measured lens, adopts the first ccd detector to gather λ ₁and λ ₂moire fringe phase-shift interference after interference light superposition.

The method of testing of the above-mentioned tuning movable phase interfere proving installation of striking rope type dual-wavelength laser, its step is as follows:

Step one: in striking rope type interference testing light path, employing centre wavelength is λ ₁and λ ₂two tunable laser carry out work as light source simultaneously, centre wavelength is λ ₁tunable laser carry out wavelength tuning according to the theoretical phase shift stepping-in amount of pi/2 and realize interfering phase shift, centre wavelength is λ ₂tunable laser carry out wavelength tuning according to the theoretical phase shift stepping-in amount of-pi/2 and realize interfering phase shift, after dichroic mirror light splitting, Single wavelength phase-shift interference under utilizing ccd detector to collect two kinds of wavelength respectively, solve by carrying out the calculating of phase shift stepping-in amount to the Single wavelength phase-shift interference under two kinds of wavelength, determine the actual phase shift stepping-in amount under respective wavelength, difference according to comparing with theoretical phase shift stepping-in amount controls tunable laser power supply, change the input current of laser instrument, change the output frequency of laser instrument, the phase shift stepping-in amount of pi/2 and-pi/2 is respectively under obtaining two kinds of wavelength, the phase shift stepping-in amount completed under dual wavelength is synchronously demarcated,

Step 2: two tunable laser as light source carry out wavelength phase shift according to demarcating the phase shift stepping-in amount obtained in step one, the 4 frame Moire fringe phase-shift interferences formed after gathering the superposition of two-way interference light by ccd detector, contain the phase information of synthetic wavelength in every frame interferogram;

Step 3: adopt dual wavelength phase-shifting algorithm to obtain tested phase information to 4 frame Moire fringe phase-shift interferences of ccd detector collection.

Wherein, the intensity signal of the Moire fringe phase-shift interference in step 2 is: be respectively λ with centre wavelength ₁and λ ₂laser tuning light source carry out wavelength phase-shifting interference measuring simultaneously, then the intensity signal of kth step movable phase interfere moiré topography is:

$I_k=I_a+I_b\cos [\frac{2\mathrm{\&pi;h}(x,y)}{{\mathrm{\&lambda;}}_1}+\frac{2\mathrm{\&pi;h}(x,y)}{{\mathrm{\&lambda;}}_2}+\frac{1}{2}k({\mathrm{\&delta;}}_1+{\mathrm{\&delta;}}_2)]\&times;\cos [{\mathrm{\&phi;}}_{\mathrm{eq}}+\frac{1}{2}k({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)]$

Wherein, k is the sequence number of 4 frame Moire fringe phase-shift interferences, i.e. k=1,2,3,4, I _afor background light intensity, I _bfor intensity modulation degree, h (x, y) for interference cavity long, h (x, y) contains the face shape information of tested surface, φ _eqfor synthetic wavelength phase data, namely in step 3 to the dual wavelength phase-shifting algorithm of Moire fringe phase-shift interference process be:

Because the phase shift stepping-in amount under two kinds of wavelength is respectively pi/2 and-pi/2, then kth walks in the intensity signal expression formula of movable phase interfere moiré topography in phase shift stepping-in amount be 0, its value and phase shift stepping-in amount have nothing to do, and comprise latter one of synthetic wavelength phase place in phase shift stepping-in amount be pi/2, then the intensity signal of kth step movable phase interfere moiré topography is:

$I_k=I_a+I_b\mathrm{cis}[\frac{2\mathrm{\&pi;h}(x,y)}{{\mathrm{\&lambda;}}_1}+\frac{2\mathrm{\&pi;h}(x,y)}{{\mathrm{\&lambda;}}_2}]\&times;\cos [{\mathrm{\&phi;}}_{\mathrm{eq}}+(k-1)\frac{\mathrm{\&pi;}}{2}]$

Then adopt traditional four step phase-shifting algorithms can extract the phase of synthetic wavelength _eqinformation, namely the face shape information of tested surface is obtained after phase unwrapping.

The present invention compared with prior art, its remarkable advantage:

(1) problem of Phase-shifting Errors under the different wave length caused for the employing PZT phase shift of traditional double wavelength movable phase interfere proving installation, adopt two different tunable laser of centre wavelength to realize the phase shift of frequency conversion wavelength separately, the accurate phase shift under different wave length can be controlled.Meanwhile, without the need to promoting phase shifting device, the Phase-shifting Errors under the different wave length that PZT phase shift causes can not be introduced.

(2) two kinds of wavelength light sources are adopted to work successively for traditional double wavelength movable phase interfere proving installation, need the problem of carrying out phase shift demarcation successively respectively, adopt two different tunable laser of centre wavelength to work simultaneously, carry out light splitting by dichroic mirror, obtain λ respectively ₁and λ ₂phase-shift interference, after computer disposal, output signal to λ respectively ₁tunable laser control power supply and λ ₂tunable laser control power supply, control λ ₁tunable laser and λ ₂tunable laser realize accurate wavelength phase shift, guarantee λ ₁and λ ₂phase shift stepping-in amount be respectively pi/2 and-pi/2, synchronously complete under dual wavelength phase shift demarcate.

(3) for the interference testing that traditional double wavelength movable phase interfere proving installation adopts two kinds of wavelength light sources to carry out under two kinds of wavelength successively, the problem of the phase data of synthetic wavelength just can be solved after obtaining the phase data under each wavelength, adopt two different tunable laser of centre wavelength to work simultaneously, carry out wavelength tuning phase shift test, moiré topography after two kinds of wavelength measurement interferogram superpositions is directly processed, extract synthetic wavelength phase data, the leaching process of synthetic wavelength phase data is simple fast.

Accompanying drawing explanation

Fig. 1 is according to striking rope type dual-wavelength laser of the present invention tuning movable phase interfere proving installation principle schematic.

Embodiment

Composition graphs 1, the tuning movable phase interfere proving installation of a kind of striking rope type dual-wavelength laser of the present invention, is characterized in that: comprising centre wavelength is λ ₁tunable laser 1, first beam expanding lens 2, first Amici prism 3, standard mirror 4, measured lens 5, centre wavelength be λ ₁tunable laser 6, second beam expanding lens 7, second Amici prism 8, first spectroscope 9, first imaging len 10, first ccd detector 11, second imaging len 13, second ccd detector 14, the 3rd imaging len 15, the 3rd ccd detector 16 and cutoff wavelength be λ ₃dichroic mirror 12, wherein λ ₁≠ λ ₂, min (λ ₁, λ ₂) < λ ₃<max (λ ₁, λ ₂); Setting gradually centre wavelength is λ ₁tunable laser 1, first beam expanding lens 2 and the first Amici prism 3, the optical axis at their places is primary optic axis; Set gradually the second Amici prism 8, first spectroscope 9, cutoff wavelength is λ ₃dichroic mirror 12, the 3rd imaging len 15 and the 3rd ccd detector 16, the optical axis at their places is the second optical axis; Setting gradually centre wavelength is λ ₂tunable laser 6, second beam expanding lens 7, second Amici prism 8, first Amici prism 3, standard mirror 4 and measured lens 5, the optical axis at their places is the 3rd optical axis; Set gradually the first spectroscope 9, first imaging len 10 and the first ccd detector 11, the optical axis at their places is the 4th optical axis; Setting gradually cutoff wavelength is λ ₃dichroic mirror 12, second imaging len 13 and the second ccd detector 14, the optical axis at their places is the 5th optical axis, primary optic axis and the second optical axis are vertical with the 3rd optical axis respectively, 4th optical axis is vertical with the second optical axis respectively with the 5th optical axis, first spectroscope 9 is 45 ° with the second optical axis included angle of vertical direction, and cutoff wavelength is the high pass dichroic mirror 12 of λ is 135 ° with the second optical axis included angle of vertical direction; Be λ by centre wavelength ₁the wavelength that sends of tunable laser 1 be λ ₁laser after the first beam expanding lens 2 beam-expanding collimation, become the heavy caliber parallel beam of collimation, this parallel beam reflexes to standard mirror 4 and measured lens 5 through the first Amici prism 3, and defining wavelength is λ ₁laser tuning movable phase interfere optical system for testing; Be λ by centre wavelength ₂the wavelength that sends of tunable laser 6 be λ ₂laser after the second beam expanding lens 7 beam-expanding collimation, become the heavy caliber parallel beam of collimation, this parallel beam is incident to standard mirror 4 and measured lens 5 through the second Amici prism 8 and the first Amici prism 3, and defining wavelength is λ ₂laser tuning movable phase interfere optical system for testing; The wavelength being incident to standard mirror 4 and measured lens 5 is λ ₁and λ ₂light wave through standard mirror 4 and measured lens 5 back reflection, the first spectroscope 9 is reflexed to by the second Amici prism 8 through after the first Amici prism 3, two bundles are divided into after the first spectroscope 9, a branch of is the first reflected light, another bundle is the first transmitted light, the first reflected light finally by the first imaging len 10 gather by the first ccd detector 11 and define λ ₁and λ ₂moire fringe phase-shift interference after interference light superposition gathers light path, and the first transmitted light is λ through being incident to cutoff wavelength after the first spectroscope 9 ₃dichroic mirror 12, first transmitted light be λ through cutoff wavelength ₃dichroic mirror 12 after be divided into two bundles, a branch of wavelength is λ ₂the second reflected light, another bundle for wavelength be λ ₁the second transmitted light, the second reflected light is finally gathered formation by the second ccd detector 14 through the second imaging len 13 and realizes λ ₂the signals collecting light path of accurate phase shifting control, the second transmitted light is finally gathered formation by the 3rd ccd detector 16 through the 3rd imaging len 15 and realizes λ ₁the signals collecting light path of accurate phase shifting control.

This device selects central wavelength lambda ₁for tunable laser 1 and the λ of 687nm ₂for the tunable laser 6 of 633nm is as light source, wherein the tunable wavelength scope of tunable laser 1 is 682 ~ 692nm, and the tunable wavelength scope of tunable laser 6 is 632.5 ~ 635nm, and dichroic mirror 12 is cutoff wavelength λ ₃the high pass dichroic mirror of=638nm, concrete test process is as follows:

Step one: in striking rope type interference testing light path, adopts central wavelength lambda ₁for tunable laser 1 and the λ of 687nm ₂for the tunable laser 6 of 633nm carries out work simultaneously, wherein tunable laser 1 carries out wavelength tuning realization interference phase shift according to the theoretical phase shift stepping-in amount of pi/2, tunable laser 6 is carried out wavelength tuning according to the theoretical phase shift stepping-in amount of-pi/2 and is realized interfering phase shift, light wave after the superposition of two kinds of wavelength after high pass dichroic mirror 12 light splitting, wavelength X ₁for the light wave of 687nm is collected λ through imaging len 15 by the 3rd ccd detector 16 ₁for the Single wavelength phase-shift interference under 687nm, wavelength X ₂for the light wave of 633nm is collected λ through imaging len 13 by the 3rd ccd detector 14 ₂for the Single wavelength phase-shift interference under 633nm, solve by carrying out the calculating of phase shift stepping-in amount to the Single wavelength phase-shift interference under two kinds of wavelength, determine the actual phase shift stepping-in amount under respective wavelength, difference according to comparing with theoretical phase shift stepping-in amount controls tunable laser power supply, change the input current of laser instrument, change the output frequency of laser instrument, obtain λ ₁for 687nm and λ ₂for being respectively the phase shift stepping-in amount of pi/2 and-pi/2 under 633nm, the phase shift stepping-in amount completed under dual wavelength is synchronously demarcated;

Step 2: carry out wavelength phase shift according to demarcating the phase shift stepping-in amount obtained in step one as the tunable laser 1 of light source and tunable laser 6, the 4 frame Moire fringe phase-shift interferences formed after gathering the superposition of two-way interference light by the first ccd detector 11, contain the phase information of synthetic wavelength in every frame interferogram;

Step 3: adopt dual wavelength phase-shifting algorithm to obtain tested phase information to the 4 frame Moire fringe phase-shift interferences that the first ccd detector 11 gathers, solve the face shape of tested surface after phase unwrapping.

This device selects central wavelength lambda ₁for tunable laser 1 and the λ of 633nm ₂for the tunable laser 6 of 816nm is as light source, wherein the tunable wavelength scope of tunable laser 1 is 632.5 ~ 635nm, and the tunable wavelength scope of tunable laser 6 is 815 ~ 825nm, and dichroic mirror 12 is cutoff wavelength λ ₃the low pass dichroic mirror of=805nm, concrete test process is as follows:

Step one: in striking rope type interference testing light path, adopts central wavelength lambda ₁for tunable laser 1 and the λ of 633nm ₂for the tunable laser 6 of 633nm carries out work simultaneously, wherein tunable laser 1 carries out wavelength tuning realization interference phase shift according to the theoretical phase shift stepping-in amount of pi/2, tunable laser 6 is carried out wavelength tuning according to the theoretical phase shift stepping-in amount of-pi/2 and is realized interfering phase shift, light wave after the superposition of two kinds of wavelength after low pass dichroic mirror 12 light splitting, wavelength X ₁for the light wave of 633nm is collected λ through imaging len 15 by the 3rd ccd detector 16 ₁for the Single wavelength phase-shift interference under 633nm, wavelength X ₂for the light wave of 816nm is collected λ through imaging len 13 by the 3rd ccd detector 14 ₂for the Single wavelength phase-shift interference under 816nm, solve by carrying out the calculating of phase shift stepping-in amount to the Single wavelength phase-shift interference under two kinds of wavelength, determine the actual phase shift stepping-in amount under respective wavelength, difference according to comparing with theoretical phase shift stepping-in amount controls tunable laser power supply, change the input current of laser instrument, change the output frequency of laser instrument, obtain λ ₁for 633nm and λ ₂for being respectively the phase shift stepping-in amount of pi/2 and-pi/2 under 816nm, the phase shift stepping-in amount completed under dual wavelength is synchronously demarcated;

Step 2: carry out wavelength phase shift according to demarcating the phase shift stepping-in amount obtained in step one as the tunable laser 1 of light source and tunable laser 6, the 4 frame Moire fringe phase-shift interferences formed after gathering the superposition of two-way interference light by the first ccd detector 11, contain the phase information of synthetic wavelength in every frame interferogram;

Step 3: adopt dual wavelength phase-shifting algorithm to obtain tested phase information to the 4 frame Moire fringe phase-shift interferences that the first ccd detector 11 gathers, solve the face shape of tested surface after phase unwrapping.

Claims (8)

1. the tuning movable phase interfere proving installation of striking rope type dual-wavelength laser, is characterized in that: comprising centre wavelength is λ ₁tunable laser (1), the first beam expanding lens (2), the first Amici prism (3), standard mirror (4), measured lens (5), centre wavelength be λ ₁tunable laser (6), the second beam expanding lens (7), the second Amici prism (8), the first spectroscope (9), the first imaging len (10), the first ccd detector (11), the second imaging len (13), the second ccd detector (14), the 3rd imaging len (15), the 3rd ccd detector (16) and cutoff wavelength be λ ₃dichroic mirror (12), wherein λ ₁≠ λ ₂, min (λ ₁, λ ₂) < λ ₃<max (λ ₁, λ ₂); Setting gradually centre wavelength is λ ₁tunable laser (1), the first beam expanding lens (2) and the first Amici prism (3), the optical axis at their places is primary optic axis; Set gradually the second Amici prism (8), the first spectroscope (9), cutoff wavelength be λ ₃dichroic mirror (12), the 3rd imaging len (15) and the 3rd ccd detector (16), the optical axis at their places is the second optical axis; Setting gradually centre wavelength is λ ₂tunable laser (6), the second beam expanding lens (7), the second Amici prism (8), the first Amici prism (3), standard mirror (4) and measured lens (5), the optical axis at their places is the 3rd optical axis; Set gradually the first spectroscope (9), the first imaging len (10) and the first ccd detector (11), the optical axis at their places is the 4th optical axis; Setting gradually cutoff wavelength is λ ₃dichroic mirror (12), the second imaging len (13) and the second ccd detector (14), the optical axis at their places is the 5th optical axis, primary optic axis and the second optical axis are vertical with the 3rd optical axis respectively, and the 4th optical axis is vertical with the second optical axis respectively with the 5th optical axis; Be λ by centre wavelength ₁the wavelength that sends of tunable laser (1) be λ ₁laser after the first beam expanding lens (2) beam-expanding collimation, become the heavy caliber parallel beam of collimation, this parallel beam reflexes to standard mirror (4) and measured lens (5) through the first Amici prism (3), and defining wavelength is λ ₁laser tuning movable phase interfere optical system for testing; Be λ by centre wavelength ₂the wavelength that sends of tunable laser (6) be λ ₂laser after the second beam expanding lens (7) beam-expanding collimation, become the heavy caliber parallel beam of collimation, this parallel beam is incident to standard mirror (4) and measured lens (5) through the second Amici prism (8) and the first Amici prism (3), and defining wavelength is λ ₂laser tuning movable phase interfere optical system for testing; The wavelength being incident to standard mirror (4) and measured lens (5) is λ ₁and λ ₂light wave through standard mirror (4) and measured lens (5) back reflection, the first spectroscope (9) is reflexed to by the second Amici prism (8) through after the first Amici prism (3), two bundles are divided into after the first spectroscope (9), a branch of is the first reflected light, another bundle is the first transmitted light, the first reflected light finally by the first imaging len (10) gather by the first ccd detector (11) and define λ ₁and λ ₂moire fringe phase-shift interference after interference light superposition gathers light path, and the first transmitted light is λ through being incident to cutoff wavelength after the first spectroscope (9) ₃dichroic mirror (12), the first transmitted light is λ through cutoff wavelength ₃dichroic mirror (12) after be divided into two bundles, a branch of wavelength is λ ₂the second reflected light, another bundle for wavelength be λ ₁the second transmitted light, the second reflected light through the second imaging len (13) finally by the second ccd detector (14) gather formation realize λ ₂the signals collecting light path of accurate phase shifting control, the second transmitted light is finally gathered formation by the 3rd ccd detector (16) through the 3rd imaging len (15) and realizes λ ₁the signals collecting light path of accurate phase shifting control.

2. the tuning movable phase interfere proving installation of striking rope type dual-wavelength laser according to claim 1, it is characterized in that: the first spectroscope (11) is 45 ° with the second optical axis included angle of vertical direction, cutoff wavelength is the dichroic mirror (12) of λ is 135 ° with the second optical axis included angle of vertical direction.

3. the tuning movable phase interfere proving installation of striking rope type dual-wavelength laser according to claim 1, is characterized in that: work as λ ₁﹤ λ ₃﹤ λ ₂, dichroic mirror (12) is low pass dichroic mirror.

4. the tuning movable phase interfere proving installation of striking rope type dual-wavelength laser according to claim 1, is characterized in that: work as λ ₂﹤ λ ₃﹤ λ ₁, dichroic mirror (12) is high pass dichroic mirror.

5. the tuning movable phase interfere proving installation of striking rope type dual-wavelength laser according to claim 1, is characterized in that: employing centre wavelength is λ ₁tunable laser (2) and λ ₂tunable laser (8) according to λ ₁for pi/2 and λ ₂for the phase shift stepping-in amount of-pi/2 carries out wavelength phase shift, synchronously the detection of wavelength movable phase interfere is carried out to measured lens (5), adopt the first ccd detector (11) to gather λ ₁and λ ₂moire fringe phase-shift interference after interference light superposition.

6., based on the method for testing of the tuning movable phase interfere proving installation of striking rope type dual-wavelength laser according to claim 1, it is characterized in that: step is as follows:

Step one: in striking rope type interference testing light path, employing centre wavelength is λ ₁and λ ₂two tunable laser carry out work as light source simultaneously, centre wavelength is λ ₁tunable laser carry out wavelength tuning according to the theoretical phase shift stepping-in amount of pi/2 and realize interfering phase shift, centre wavelength is λ ₂tunable laser carry out wavelength tuning according to the theoretical phase shift stepping-in amount of-pi/2 and realize interfering phase shift, after dichroic mirror light splitting, Single wavelength phase-shift interference under utilizing ccd detector to collect two kinds of wavelength respectively, solve by carrying out the calculating of phase shift stepping-in amount to the Single wavelength phase-shift interference under two kinds of wavelength, determine the actual phase shift stepping-in amount under respective wavelength, difference according to comparing with theoretical phase shift stepping-in amount controls tunable laser power supply, change the input current of laser instrument, change the output frequency of laser instrument, the phase shift stepping-in amount of pi/2 and-pi/2 is respectively under obtaining two kinds of wavelength, the phase shift stepping-in amount completed under dual wavelength is synchronously demarcated,

Step 2: two tunable laser as light source carry out wavelength phase shift according to demarcating the phase shift stepping-in amount obtained in step one, the 4 frame Moire fringe phase-shift interferences formed after gathering the superposition of two-way interference light by ccd detector, contain the phase information of synthetic wavelength in every frame interferogram;

Step 3: adopt dual wavelength phase-shifting algorithm to obtain tested phase information to 4 frame Moire fringe phase-shift interferences of ccd detector collection.

7. the tuning movable phase interfere method of testing of one according to claim 6 striking rope type dual-wavelength laser, is characterized in that: the intensity signal of the Moire fringe phase-shift interference in step 2 is as follows:

λ is respectively with centre wavelength ₁and λ ₂laser tuning light source carry out wavelength phase-shifting interference measuring simultaneously, then the intensity signal of kth step movable phase interfere moiré topography is:

$I_k=I_a+I_b\mathrm{cis}[\frac{2\mathrm{\&pi;h}(x,y)}{{\mathrm{\&lambda;}}_1}+\frac{2\mathrm{\&pi;h}(x,y)}{{\mathrm{\&lambda;}}_2}]\&times;\cos [{\mathrm{\&phi;}}_{\mathrm{eq}}+(k-1)\frac{\mathrm{\&pi;}}{2}]$

Wherein, k is the sequence number of 4 frame Moire fringe phase-shift interferences, i.e. k=1,2,3,4, I _afor background light intensity, I _bfor intensity modulation degree, h (x, y) for interference cavity long, h (x, y) contains the face shape information of tested surface, φ _eqfor synthetic wavelength phase data, namely ${\mathrm{\&phi;}}_{\mathrm{eq}}=2\mathrm{\&pi;h}(x,y)(\frac{1}{{\mathrm{\&lambda;}}_1}-\frac{1}{{\mathrm{\&lambda;}}_2}).$

8. the tuning movable phase interfere method of testing of one according to claim 6 striking rope type dual-wavelength laser, is characterized in that: in step 3 to the dual wavelength phase-shifting algorithm of Moire fringe phase-shift interference process be:

Because the phase shift stepping-in amount under two kinds of wavelength is respectively pi/2 and-pi/2, then kth walks in the intensity signal expression formula of movable phase interfere moiré topography in phase shift stepping-in amount be 0, its value and phase shift stepping-in amount have nothing to do, and comprise latter one of synthetic wavelength phase place in phase shift stepping-in amount be pi/2, then adopt traditional four step phase-shifting algorithms can extract the phase of synthetic wavelength _eqinformation, obtain the face shape information of tested surface after phase unwrapping.