CN103063156B - A kind of method of dual-wavelength shear interference measurement body surface curvature under hot environment - Google Patents

Abstract

A method for dual-wavelength shear interference measurement body surface curvature under hot environment, relates to body structure surface deformation measurement, Experiments of Optics technical field under high temperature.The method builds dual wavelength shear interference system, at high temperature measure body surface Curvature varying, under getting rid of high temperature, air turbulence is on the impact of body surface curvature measurement, utilizes described dual wavelength shear interference system accurately to obtain body surface curvature topographical information in high temperature environments.The method utilizes shear interference to measure body surface curvature, utilizes air different to the refractive index of different wave length light, and removing air turbulence in hot environment affects measurement result.Structure of the present invention is simple, is easy to realize, and under solving hot environment, air turbulence is to the interference problem of optical measurement body surface curvature pattern, and can realize whole audience real-time online measuring body surface curvature pattern.

Description

A kind of method of dual-wavelength shear interference measurement body surface curvature under hot environment

Technical field

Measure body surface curvature topography measurement field under the present invention relates to high temperature, particularly relate to a kind of dual-wavelength shear interference measurement body surface curvature method under hot environment, belong to body structure surface deformation measurement, Experiments of Optics technical field under high temperature.

Background technology

Measure the while that deformation of body being of the utmost importance in engineering extremely difficult in hot environment, conventional contact type measurement often occurs that measuring sensor preparation requires the shortcomings such as high, easy inefficacy in high temperature environments, and contactless optical measurement faces air heats disturbance causes very large interference puzzlement to measurement result.

Coherent gradient sensing method has been develop very ripe method as a kind of optical means measuring surface of test piece curvature of mechanics field, and curvature is the important geometry parameter characterizing surface of test piece pattern, carry out integration by the surface of test piece curvature obtained and can obtain surface of test piece pattern, can also pass through film surface curvature estimation membrane stress to substrate film system in addition, test surface of test piece curvature plays an important role to the distortion of observation surface of test piece, testing film mechanical property etc.Coherent gradient sensing method has the advantage of whole audience noncontact real-time online, special the method is insensitive to vibration, but it is the same with general measuring method, the method is responsive to air turbulence, and particularly in hot environment, the violent disturbance of air heats causes very large interference that measurement almost cannot be carried out to measurement.

A kind of approach utilizing optical touchless method to measure body surface distortion that solves in hot environment vacuumizes testing environment residing for test specimen, and then get rid of the interference that in hot environment, the violent disturbance of air heats causes measurement.This is more effective to test micro devices, the experimental situation of the larger test specimen of volume ratio is vacuumized more difficult and sometimes almost impossible, thus find have air to exist in environment under high temperature to measure body surface deformation method significant in experimental technique and engineer applied.

Summary of the invention

The invention provides the method for dual-wavelength shear interference measurement body surface curvature under a kind of hot environment, under can removing high temperature, air turbulence affects body surface curvature topography measurement, realize real-time online measuring body surface curvature pattern under high temperature, and the method is insensitive to vibration.

Technical scheme of the present invention is as follows:

A kind of dual-wavelength shear interference measurement body surface curvature method under hot environment, it is characterized in that, described method adopts dual wavelength shear interference curvature measuring system, described dual wavelength shear interference curvature measuring system, comprising: dual wavelength polarization laser, beam-expanding system, spectroscope, polarization splitting prism, the first grating, the second grating, the 3rd grating, the 4th grating, the first lens, the second lens, the first filter screen, the second filter screen, the first imaging screen, the second imaging screen, the first CCD camera, the second CCD camera, data processing and display system;

Described dual wavelength polarization laser sends and a branch ofly contains two wavelength and the orthogonal polarization laser of direction of vibration, this laser reflexes to surface of test piece through spectroscope after beam-expanding system expands, test specimen is placed in heated environment, laser is propagated through spectroscope after surface of test piece reflection, by polarization splitting prism, different for direction of vibration two wavelength polarization lasers are separately propagated, the laser frequency propagated through polarization splitting prism is f1, frequency is that the laser of f1 interferes formation interference fringe through the first grating and the second grating shearing, the imaging on the first imaging screen of the first filter screen is passed through through after the first lens, by the interference fringe the first CCD camera shooting record first imaging screen comprising surface of test piece topographical information, be f2 by the laser frequency of polarization splitting prism reflections propagate, f2 fraction of laser light interferes formation interference fringe through the 3rd grating and the 4th grating shearing, the imaging on the second imaging screen of the second filter screen is passed through through after the second lens, by the interference fringe the second CCD camera shooting record second imaging screen comprising surface of test piece topographical information, the information of the first CCD camera and the second CCD camera shooting record is passed to data processing and display system processes, and finally obtain and show the surface curvature distribution of test specimen in high-temperature heating situation,

Curvature κ _xx, κ _yy, κ _xycalculation relational expression is as follows:

${\mathrm{\κ}}_{xx}=\frac{p}{2\mathrm{\Δ}}\frac{g\left({\mathrm{\λ}}_1\right)\frac{\∂n_2^{\left(x\right)}}{\∂x}-g\left({\mathrm{\λ}}_2\right)\frac{\∂n_1^{\left(x\right)}}{\∂x}}{g\left({\mathrm{\λ}}_1\right)-g\left({\mathrm{\λ}}_2\right)}$

${\mathrm{\κ}}_{yy}=\frac{p}{2\mathrm{\Δ}}\frac{g\left({\mathrm{\λ}}_1\right)\frac{\∂n_2^{\left(y\right)}}{\∂y}-g\left({\mathrm{\λ}}_2\right)\frac{\∂n_1^{\left(y\right)}}{\∂y}}{g\left({\mathrm{\λ}}_1\right)-g\left({\mathrm{\λ}}_2\right)}$

${\mathrm{\κ}}_{xy}=\frac{p}{2\mathrm{\Δ}}\frac{g\left({\mathrm{\λ}}_1\right)\frac{\∂n_2^{\left(y\right)}}{\∂x}-g\left({\mathrm{\λ}}_2\right)\frac{\∂n_1^{\left(y\right)}}{\∂x}}{g\left({\mathrm{\λ}}_1\right)-g\left({\mathrm{\λ}}_2\right)}$

Wherein κ _xx, κ _yy, κ _xyfor surface of test piece curvature, x direction is horizontal direction, and y is vertical direction, g (λ ₁), g (λ ₂) be respectively the air refraction of frequency f 1, f2 laser, be respectively the fringe number of grating orientation f1, f2 laser level direction shear interference+1 grade of interference fringe in the horizontal direction, be respectively the fringe number of grating orientation vertically f1, f2 laser vertical direction shear interference+1 grade of interference fringe, p is raster density constant, and Δ is the spacing of adjacent two gratings.

Technical scheme provided by the invention has the following advantages and high-lighting effect: the method utilizes the different interference of removing air turbulence and producing measurement of refractive index in atmosphere of different laser, two wavelength lasers reflect the interference fringe of carrying out shear interference formation by surface of test piece and obtain surface of test piece curvature by certain relational calculus, integration is carried out to curvature and can obtain surface of test piece slope and pattern, achieve and engineering to get rid of in hot environment air turbulence to the impact of optical measurement object surface appearance, the coherent gradient sensing method adopted measures the advantage that surface of test piece curvature itself has whole audience real-time online measuring, and it is insensitive to vibration, this has vital role to measuring body surface distortion under hot environment in engineering.

Accompanying drawing explanation

Fig. 1 is the measuring system schematic diagram of dual-wavelength shear interference measurement body surface curvature under hot environment of the present invention.

Fig. 2 is coherent gradient sensing method shear interference schematic diagram.

In accompanying drawing: 1-high temperature heat source; 2-measures test specimen; 3-dual wavelength polarization laser; 4-beam-expanding system; 5-spectroscope; 6-polarization splitting prism; 7-first grating; 8-second grating; 9-the 3rd grating; 10-the 4th grating; 11-first convex lens; 12-second convex lens; 13-first filter screen; 14-second filter screen; 15-first imaging screen; 16-second imaging screen; 17-first CCD camera; 18-second CCD camera; 19-data processing and display system.

Embodiment

Further illustrate concrete structure of the present invention and embodiment below in conjunction with accompanying drawing, but should not limit the scope of the invention with this.

Fig. 1 is the measuring system schematic diagram of dual-wavelength shear interference measurement body surface curvature under hot environment of the present invention.Under hot environment, the measuring system of dual-wavelength shear interference measurement body surface curvature comprises: dual wavelength polarization laser 3, beam-expanding system 4, spectroscope 5, polarization splitting prism 6, first grating 7, second grating 8, the 3rd grating 9, the 4th grating 10, first convex lens 11, second convex lens 12, first filter screen 13, second filter screen 14, first imaging screen 15, second imaging screen 16, first CCD camera 17, second CCD camera 18 and data processing and display system 19.

Described dual wavelength polarization laser 3 sends and a branch ofly contains two wavelength and the orthogonal polarization laser of direction of vibration, this laser reflexes to test specimen 2 surface through spectroscope 5 after beam-expanding system 4 expands, test specimen is placed in heated environment, laser is propagated through spectroscope 5 after surface of test piece reflection, by polarization splitting prism 6, different for direction of vibration two wavelength polarization laser frequencies are respectively f1, f2 separately propagates, the laser frequency propagated through polarization splitting prism is f1, frequency is that the laser of f1 forms interference fringe through the first grating 7 and the second grating 8 shear interference, the imaging on the first imaging screen 15 of the first filter screen 13 is passed through through after the first convex lens 11, first CCD camera 17 takes interference fringe record first imaging screen comprising surface of test piece topographical information, spectroscope 5, polarization splitting prism 6, first grating 7, second grating 8, first convex lens 11, first filter screen 13, first imaging screen 15 is on same optical axis, first grating and the second grating orientation are successively placed along level and vertical direction, be f2 by the laser frequency of polarization splitting prism 6 reflections propagate, f2 fraction of laser light forms interference fringe through the 3rd grating 9 and the 4th grating 10 shear interference, the imaging on the second imaging screen 16 of the second filter screen 14 is passed through through after the second convex lens 12, second CCD camera 18 takes interference fringe record second imaging screen comprising surface of test piece topographical information, 3rd grating 9, the 4th grating 10, second convex lens 12, second filter screen 14, second imaging screen 16 are on same optical axis, and the 3rd grating and the 4th grating orientation are successively placed along level and vertical direction, the information of the first CCD camera and the second CCD camera shooting record is passed to data processing and display system 19 processes, and is finally obtained and show the surface curvature distribution of test specimen in high-temperature heating situation and topographical information by computing.

Principle of work of the present invention is as follows:

Fig. 2 is dual wavelength coherent gradient sensing method shear interference schematic diagram, the optical axis of xy plane orthogonal in device, first grating 7 is all parallel with y-axis direction with the second grating 8 principal direction, z direction is parallel to optical axis, the laser that its medium frequency is f1 through polarization splitting prism 6 by the laser reflected through surface of test piece incides the first grating 7, note wherein a certain incident beam light path is S (x, y), diffracted beam at different levels is obtained, in order to only marked Zero-order diffractive light beam E in reduced graph 2 after the first grating 7 diffraction ₀with first-order diffraction light beam E ₁, θ is angle of diffraction, can be provided by optical grating diffraction equation:

θ＝arcsin(λ/p)≈λ/p(1)

(1) in formula, θ is angle of diffraction, and λ is laser wavelength of incidence, and p is raster density constant.

The light path S (x, y) that on test specimen, the laser propagation of (x, y) point reflection has to grating represents, can obtain the available following formula of light path S (x, y) express by geometric analysis:

$S=2f(x,y)+\underset{0}{\overset{L}{\∫}}Ndz=2f(x,y)+\underset{0}{\overset{L}{\∫}}P(x,y,z)g\left(\mathrm{\λ}\right)dz=2f(x,y)+g\left(\mathrm{\λ}\right)F(x,y)---\left(2\right)$

Wherein, f (x, y) is surface of test piece pattern function, N is air refraction, N=N (ρ (x, y, z), λ), refractive index is relevant with atmospheric density ρ and laser wavelength lambda, and atmospheric density ρ is function ρ=ρ (x of locus, y, z), L is laser propagation optical path length, and air refraction N is volume coordinate function P (x, y, z) and the product of optical maser wavelength function g (λ), laser propagation direction is z direction, P (x, y, z) integration is F (x, y) in the z-direction

As shown in Figure 2, laser is interfered by two grating shearings and is formed bright fringess, and on test specimen, the laser of (x, y) point reflection is through the E of first optical grating diffraction ₁level with the laser of (x, y+ ω) point reflection on test specimen through the E* of the first optical grating diffraction ₀level interferes through the second grating, and on test specimen, the light path of (x, y+ ω) point reflection laser represents with S (x, y+ ω), and interfering that to produce the condition of bright fringes be the optical path difference that laser is restrainted in interference two is the integral multiple of wavelength:

S(x,y+ω)-S(x,y)＝nλ,n＝0,±1,±2...(3)

N is fringe order, (3) formula is written as

$\frac{S(x,y+\mathrm{\ω})-S(x,y)}{\mathrm{\ω}}=\frac{n\mathrm{\λ}}{\mathrm{\ω}},n=0,\±1,\±2...\left(4\right)$

When offset distance ω is very little, (4) formula can be approximately

$\frac{\∂S(x,y)}{\∂y}=\frac{n\mathrm{\λ}}{\mathrm{\ω}},n=0,\±1,\±2...\left(5\right)$

Wherein shear side-play amount p is raster density constant, Δ be two grating spaces from, (5) formula of substitution obtains

$\frac{\∂S(x,y)}{h}=\frac{np}{\mathrm{\Δ}},n=0,\±1,\±2...\left(6\right)$

By two grating principal direction adjustment in the horizontal direction, in like manner can obtain

$\frac{\∂S(x,y)}{\∂x}=\frac{np}{\mathrm{\Δ}},n=0,\±1+2...\left(7\right)$

After second grating, place convex lens, these convex lens are by beams converge parallel to each other in these diffracted beams, and its light distribution can be observed on the back focal plane of convex lens.Focal plane is placed an optical filtering screen, an optical filtering hole opened by screen only allows+1 order diffraction light pass through, CCD shooting record is placed afterwards from optical filtering screen through beating the interference fringe on imaging screen, by carrying out to striped the relevant information that analyzing and processing can obtain film surface appearance at screen.

Surface of test piece can be obtained by geometric relationship and rise and fall little and incident laser when almost incident perpendicular to surface of test piece, surface of test piece curvature κ _{α β}≈ f _{, α β}, therefore by (7) Shi Ke get

$\frac{{\∂}^{2}S}{\∂x^2}=\frac{p}{\mathrm{\Δ}}\frac{\∂n^{\left(x\right)}}{\∂x}=2{\mathrm{\κ}}_{xx}+\frac{{\∂}^{2}F(x,y)}{\∂x^2}g\left(\mathrm{\λ}\right)---\left(8\right)$

N ^(x)for the fringe number of grating orientation laser shear interference+1 grade of interference fringe in the horizontal direction, can obtain dual wavelength different frequency f1, f2 laser interference fringes processing that shear interference obtains respectively:

$\frac{p}{\mathrm{\Δ}}\frac{\∂n_1^{\left(x\right)}}{\∂x}=2{\mathrm{\κ}}_{xx}+\frac{{\∂}^{2}F(x,y)}{\∂x^2}g\left({\mathrm{\λ}}_1\right)---\left(9\right)$

$\frac{p}{\mathrm{\Δ}}\frac{\∂n_2^{\left(x\right)}}{\∂x}=2{\mathrm{\κ}}_{xx}+\frac{{\∂}^{2}F(x,y)}{\∂x^2}g\left({\mathrm{\λ}}_2\right)---\left(10\right)$

G (λ ₁), g (λ ₂) being respectively the air refraction of frequency f 1, f2 laser, can obtain by tabling look-up, be respectively the fringe number of grating orientation f1, f2 laser level direction shear interference+1 grade of interference fringe in the horizontal direction, simultaneous (9), (10) formula can obtain surface of test piece κ _xxcalculation relational expression:

${\mathrm{\κ}}_{xx}=\frac{p}{2\mathrm{\Δ}}\frac{g\left({\mathrm{\λ}}_1\right)\frac{\∂n_2^{\left(x\right)}}{\∂x}-g\left({\mathrm{\λ}}_2\right)\frac{\∂n_1^{\left(x\right)}}{\∂x}}{g\left({\mathrm{\λ}}_1\right)-g\left({\mathrm{\λ}}_2\right)}---\left(11\right)$

In like manner κ can be obtained _yy, κ _xycalculation relational expression:

${\mathrm{\κ}}_{yy}=\frac{p}{2\mathrm{\Δ}}\frac{g\left({\mathrm{\λ}}_1\right)\frac{\∂n_2^{\left(y\right)}}{\∂y}-g\left({\mathrm{\λ}}_2\right)\frac{\∂n_1^{\left(y\right)}}{\∂y}}{g\left({\mathrm{\λ}}_1\right)-g\left({\mathrm{\λ}}_2\right)}---\left(12\right)$

${\mathrm{\κ}}_{xy}=\frac{p}{2\mathrm{\Δ}}\frac{g\left({\mathrm{\λ}}_1\right)\frac{\∂n_2^{\left(y\right)}}{\∂x}-g\left({\mathrm{\λ}}_2\right)\frac{\∂n_1^{\left(y\right)}}{\∂x}}{g\left({\mathrm{\λ}}_1\right)-g\left({\mathrm{\λ}}_2\right)}---\left(13\right)$

Wherein κ _xx, κ _yy, κ _xyfor surface of test piece curvature, be respectively the fringe number of grating orientation vertically f1, f2 laser vertical direction shear interference+1 grade of interference fringe.

Claims (1)

1. the method for dual-wavelength shear interference measurement body surface curvature under a hot environment, it is characterized in that, described method adopts dual wavelength shear interference curvature measuring system, described dual wavelength shear interference curvature measuring system, comprise: dual wavelength polarization laser, beam-expanding system, spectroscope, polarization splitting prism, first grating, second grating, 3rd grating, 4th grating, first convex lens, second convex lens, first filter screen, second filter screen, first imaging screen, second imaging screen, first CCD camera, second CCD camera, data processing and display system,

Described dual wavelength polarization laser (3) sends and a branch ofly contains two wavelength and the orthogonal polarization laser of direction of vibration, this laser reflexes to test specimen (2) surface through spectroscope (5) after beam-expanding system (4) expands, test specimen is placed in heated environment, laser is propagated through spectroscope (5) after surface of test piece reflection, by polarization splitting prism (6), different for direction of vibration two wavelength polarization lasers are separately propagated, the laser frequency propagated through polarization splitting prism is f1, frequency is that the laser of f1 forms interference fringe through the first grating (7) and the second grating (8) shear interference, the first filter screen (13) is passed through afterwards in the upper imaging of the first imaging screen (15) through the first convex lens (11), by the interference fringe the first CCD camera (17) shooting record first imaging screen comprising surface of test piece topographical information, be f2 by the laser frequency of polarization splitting prism (6) reflections propagate, f2 fraction of laser light forms interference fringe through the 3rd grating (9) and the 4th grating (10) shear interference, the second filter screen (14) is passed through afterwards in the upper imaging of the second imaging screen (16) through the second convex lens (12), by the interference fringe the second CCD camera (18) shooting record second imaging screen comprising surface of test piece topographical information, the information of the first CCD camera and the second CCD camera shooting record is passed to data processing and display system (19) processes, and finally obtain and show the surface curvature distribution of test specimen in high-temperature heating situation,

The method calculates body surface curvature as follows:

Based on to air turbulence to the theoretical analysis that single wavelength shear interference light path is disturbed, laser represents with following formula to laser light path S (x, y) of surface of test piece process through disturbance air exposure:

Wherein, f (x, y) is surface of test piece pattern function, N is air refraction, N=N (ρ (x, y, z), λ), refractive index is relevant with atmospheric density ρ and laser wavelength lambda, and atmospheric density ρ is function ρ=ρ (x of locus, y, z), L is laser propagation optical path length, and air refraction N is volume coordinate function P (x, y, z) and the product of optical maser wavelength function g (λ), laser propagation direction is z direction, P (x, y, z) integration is F (x, y) in the z-direction

Remove air turbulence by dual wavelength shear interference and measure body surface curvature κ _xx, κ _yy, κ _xycalculation relational expression is as follows:

Wherein κ _xx, κ _yy, κ _xyfor surface of test piece curvature, x direction is horizontal direction, and y is vertical direction, g (λ ₁), g (λ ₂) be respectively the air refraction of frequency f 1, f2 laser, be respectively the fringe number of grating orientation f1, f2 laser level direction shear interference+1 grade of interference fringe in the horizontal direction, be respectively the fringe number of grating orientation vertically f1, f2 laser vertical direction shear interference+1 grade of interference fringe, p is raster density constant, and Δ is the spacing of adjacent two gratings.