CN102735357B - Temperature measuring device based on speckle interference and temperature measuring method adopting temperature measuring device - Google Patents

Abstract

The invention discloses a temperature measuring device based on speckle interference and a temperature measuring method adopting the temperature measuring device. The temperature measuring device based on speckle interference comprises a computer (9), a green light semiconductor laser (1), a laser beam expander (2), a transflective lens (3), a reference diffuse reflection surface (4), a heat source (6), an optical filter (7) and a CCD (Charge Coupled Device) camera (8), wherein the heat source (6) is used for heating a to-be-tested part (5), and the optical filter (7) is mounted at a shooting end of the CCD camera (8) and is used for filtering radiation light generated after the to-be-tested part (5) is heated. The problems of the present temperature measuring method that the obtained temperature measuring result is lower in accuracy, the temperature measuring scope is narrow and the temperature measuring speed is lower are solved by using the temperature measuring device based on speckle interference.

Description

Temperature measuring equipment based on speckle interference and adopt the temp measuring method of this device

Technical field

The present invention relates to a kind of temperature measuring equipment based on speckle interference and adopt the temp measuring method of this device.

Background technology

Temperature is an important parameter in scientific research, production, and the measurement of temperature is also an ancient problem.The technical know-how of traditional thermometry is fairly perfect, but, under a lot of actual measurement occasions and special condition, but there is a lot of problems in these temp measuring methods, adopt conventional measurement means to be difficult to meet the demands, therefore, with regard to needs, further to original method, carry out perfect, or explore new thermometry, to meet actual demand.

Speckle interference measuring technique is a kind of optical measuring technique first being proposed by J.M.Burch and J.T.Kardki the end of the sixties, have noncontact, measuring accuracy high, environment shockproof required operation under low, Ke Mingguang City, can carry out the features such as measurement of full field, thereby be widely used in deformation measurement and the field of non destructive testing on optically roughness surface.Development along with computer technology, electronic technology and digital image processing techniques, formed electronic speckle pattern interferometry technology (electronic speckle pattern interferometry, be called for short ESPI), it have real-time process information, in real time show interference fringe, quick and convenient, the shockproof of working environment required low and can realize the advantages such as striped automatic measurement.

The accuracy of the temperature-measuring results that existing temperature measuring equipment or method obtain is lower, temperature-measuring range is less, thermometric speed is slower.

Summary of the invention

The present invention is that the accuracy of the temperature-measuring results that existing temp measuring method obtains is lower, temperature-measuring range is less, the slow problem of thermometric in order to solve, thereby a kind of temperature measuring equipment based on speckle interference is provided and adopts the temp measuring method of this device.

Adopt following technical scheme:

A kind of temperature measuring equipment based on speckle interference, comprise computing machine (9), green light semiconductor (1), laser beam expander (2), half-reflecting half mirror (3), with reference to diffuse surface (4), thermal source (6), optical filter (7) and ccd video camera (8), thermal source (6) is for giving test specimen to be measured (5) heating; Optical filter (7) is arranged on the shooting end of ccd video camera (8), the radiant light after being heated for filtering test specimen to be measured (5); Green light semiconductor (1) emitting laser is incident to half-reflecting half mirror (3) after beam expander (2) expands, after half-reflecting half mirror (3), obtain reflected light and transmitted light, described reflected light is incident to the front surface of test specimen to be measured (5), and produces object plane reflected light; The transmitted light obtaining after half-reflecting half mirror (3) is incident to reference to diffuse surface (4) and produces and diffuse, and reflexes to half-reflecting half mirror (3); Ccd video camera (8) diffuses and the speckle image of object plane reflected light in test specimen to be measured (5) front surface stack formation for taking, and the image signal output end of described ccd video camera (8) is connected with the picture signal input end of computing machine (9); Test specimen to be measured (5) for can produce the test specimen of deformation under heating condition; Computing machine (9) carries out image subtraction by the speckle image of test specimen to be measured (5) front surface before the speckle image of test specimen to be measured (5) front surface and the heating of acquisition after the heating obtaining, and obtains blackening fringe order n; By described blackening fringe order n substitution formula:

$T=\frac{1+k_{T}E}{\mathrm{\α}1}\·\frac{\mathrm{n\λ}}{2}+T_0$

Obtain the temperature T of test specimen to be measured;

In formula: α is the cubic expansion coefficient, k _tfor isothermal compressibility, E is elastic modulus, and l is the original thickness of test specimen to be measured (5), and λ is optical maser wavelength, T ₀for initial temperature.

The described temperature measuring equipment based on speckle interference, described optical filter (7) is the green glow filter plate corresponding with green light semiconductor (1) wavelength.

The described temperature measuring equipment based on speckle interference, computing machine is embedded with Matlab software in (9), and the speckle image that described Matlab software is used for treating test block (5) front surface carries out image processing.

The described temperature measuring equipment based on speckle interference, test specimen to be measured (5) is engine housing.

The temp measuring method of the described temperature measuring equipment based on speckle interference, comprises the following steps:

Step 1, employing ccd video camera (8) are taken the speckle image of front test specimen to be measured (5) front surface of heating;

Step 2, employing thermal source (6) are treated test block (5) and are heated, and at test specimen to be measured (5), occur after deformation, adopt ccd video camera (8) to take the speckle image of rear test specimen to be measured (5) front surface of heating;

Before the heating that after the heating that step 3, employing computing machine (9) obtain step 2, the speckle image of test specimen to be measured (5) front surface and step 1 obtain, the speckle image of test specimen to be measured (5) front surface carries out image subtraction, obtains blackening fringe order n;

Step 4, the blackening fringe order n substitution formula that step 3 is obtained:

$T=\frac{1+k_{T}E}{\mathrm{\α}1}\·\frac{\mathrm{n\λ}}{2}+T_0$

Obtain the temperature T of test specimen to be measured;

In formula: α is the cubic expansion coefficient, k _tfor isothermal compressibility, E is elastic modulus, and l is the original thickness of test specimen to be measured (5), and λ is optical maser wavelength, T ₀for initial temperature.

The described temp measuring method based on speckle interference, the α of the cubic expansion coefficient described in step 4 passes through formula:

$\mathrm{\α}=\frac{1}{V}{\left(\frac{\∂V}{\∂T}\right)}_p,$

Obtain; In formula: V represents the volume of test specimen to be measured (5), and p represents pressure, T represents the temperature of test specimen to be measured (5).

The described temp measuring method based on speckle interference, the k of isothermal compressibility described in step 4 _tto pass through formula:

$k_T=-\frac{1}{V}{\left(\frac{\∂V}{\∂p}\right)}_T$

Obtain; In formula: V represents the volume of test specimen to be measured (5), and p represents pressure, T represents the temperature of test specimen to be measured (5).

Beneficial effect: the present invention is based on speckle interference technology is a kind of contactless thermometric mode, the present invention does not disturb the temperature of test specimen to be measured, do not affect test specimen to be measured temperature field and distribute, so tool accuracy of measurement of the present invention is higher, existing temp measuring method on year-on-year basis, accuracy of the present invention is 0.1 ℃; Meanwhile, the present invention has wider temperature-measuring range, and measurement range, for be heated the flexible ultimate value of restorability from room temperature to object under test, is variable according to its temperature-measuring range of different materials; Meanwhile, the present invention adopts ccd video camera, and the detection imaging time is short, adopts computing machine to process image, and speed is fast, can realize kinetic measurement; Meanwhile, the present invention can realize the temperature of small objects.

Accompanying drawing explanation

Fig. 1 is the structural representation of apparatus of the present invention;

Fig. 2 is from face deformation schematic diagram after test specimen to be measured is heated;

Fig. 3 is the speckle image of test specimen to be measured before heating;

Fig. 4 is the speckle image of test specimen to be measured after heating;

Fig. 5 is the interference fringe image of test specimen to be measured after Matlab software carries out image processing.

Embodiment

Below in conjunction with specific embodiment, the present invention is described in detail.

Embodiment one:

In conjunction with Fig. 1, this embodiment is described, temperature measuring equipment based on speckle interference, comprise computing machine 9, semiconductor laser 1 (green light semiconductor), laser beam expander 2, half-reflecting half mirror 3, with reference to diffuse surface 4, thermal source 6, optical filter 7 and ccd video camera 8, thermal source 6 is for giving test specimen 5 heating to be measured; Optical filter 7 is arranged on the shooting end of ccd video camera 8, the radiant light after being heated for filtering test specimen 5 to be measured; System emitting laser is incident to half-reflecting half mirror 3 after beam expander 2 expands, and obtains reflected light and transmitted light after half-reflecting half mirror 3, and described reflected light is incident to the front surface of test specimen 5 to be measured, and produces object plane reflected light; The transmitted light obtaining after half-reflecting half mirror 3 is incident to reference to diffuse surface 4 and produces and diffuse, and is reflected back half-reflecting half mirror 3; Ccd video camera 8 diffuses and the speckle image of object plane reflected light in the stack formation of test specimen 5 front surfaces to be measured for taking, before test specimen 5 deformation to be measured, its speckle image as shown in Figure 3, after test specimen 5 deformation to be measured, its speckle image as shown in Figure 4, the image signal output end of described ccd video camera 8 and computing machine 9, before test specimen to be measured 5 heating, its thickness is L as shown in Figure 2, and after test specimen 5 to be measured is heated, its thickness is that the picture signal input end of L+ Δ L connects as shown in Figure 2; Test specimen 5 to be measured for can produce the test specimen of deformation under heating condition.

Embodiment two:

The difference of the temperature measuring equipment based on speckle interference described in this embodiment and embodiment one is, it also comprises green light semiconductor 1, and system emitting laser is produced by green light semiconductor 1.

Embodiment three:

The difference of the temperature measuring equipment based on speckle interference described in this embodiment and embodiment two is, optical filter 7 is the green glow filter plate corresponding with green light semiconductor 1 wavelength, for filtering test specimen thermal radiation to be measured light.

Embodiment four;

The difference of the temperature measuring equipment based on speckle interference described in this embodiment and embodiment one, two or three is, in computing machine 9, be embedded with Matlab software, described Matlab software carries out image processing for treating the speckle image of test block 5 front surfaces.

Embodiment five:

The difference of the temperature measuring equipment based on speckle interference described in this embodiment and embodiment four is, test specimen 5 to be measured be various high temp objects surperficial (as engine housings).

Present embodiment is aimed at the temperature test that carry out on various high temp objects surfaces (as engine housing), can realize the temperature test to its shell under engine operating state.

Embodiment six:

The temp measuring method based on speckle interference based on embodiment one, it is realized by following steps:

Step 1, open semiconductor laser 1, adopt ccd video camera 8 to take the speckle image of test specimen 5 front surfaces to be measured before heating, obtain speckle image as shown in Figure 3.

Step 2, employing thermal source 6 are treated test block 5 and are heated, and at test specimen 5 to be measured, occur after deformation, adopt ccd video camera 8 again to take the speckle image of rear test specimen 5 front surfaces to be measured of heating; Obtain speckle image as shown in Figure 4.

After the heating that step 3, employing computing machine 9 obtain step 2, before the speckle image of test specimen 5 front surfaces to be measured and the heating of step 1 acquisition, the speckle image of test specimen 5 front surfaces to be measured carries out image subtraction, obtains blackening fringe order n;

Step 4, the blackening fringe order n substitution formula that step 3 is obtained:

$T=\frac{1+k_{T}E}{\mathrm{\α}1}\·\frac{\mathrm{n\λ}}{2}+T_0$

Obtain the temperature T of test specimen to be measured;

In formula: α is the cubic expansion coefficient, k _tfor isothermal compressibility, E is elastic modulus, and l is the original thickness of test specimen 5 to be measured, and λ is optical maser wavelength, T ₀for initial temperature.

The α of the cubic expansion coefficient described in step 4 passes through formula:

$\mathrm{\α}=\frac{1}{V}{\left(\frac{\∂V}{\∂T}\right)}_p,$

Obtain; In formula: V represents the volume of test specimen 5 to be measured, and p represents pressure, T represents the temperature of test specimen 5 to be measured.

The k of isothermal compressibility described in step 4 _tto pass through formula:

$k_T=-\frac{1}{V}{\left(\frac{\∂V}{\∂p}\right)}_T$

Obtain; In formula: V represents the volume of test specimen 5 to be measured, and p represents pressure, T represents the temperature of test specimen 5 to be measured.

In the present invention, expansion of solids meets the equation of state:

V(T，p)＝V ₀(T ₀，0)[1+α(T-T ₀)-k _Tp]

:

$\frac{V(T,p)}{V_0(T_0,0)}=\frac{l+\mathrm{\Δl}}{l}1+\mathrm{\ϵ}$

That is:

1+ε＝1+α(T-T ₀)-k _Tp

V wherein ₀represent the volume before test specimen 5 heating to be measured, V represents the volume after test specimen 5 heating to be measured, and α is the cubic expansion coefficient, k _tfor isothermal compressibility, p represents pressure, T ₀represent the temperature before test specimen 5 heating to be measured, T represents the temperature after test specimen 5 heating to be measured, and ε represents the relative deformation amount of test specimen 5 to be measured.

For elastic body tensile deformation:

$\frac{F}{S}=E\frac{\mathrm{\Δl}}{l}$

In formula, F is the suffered positive pressure of elastic body, and S is elastomeric lifting surface area

After distortion, be:

p＝Eε

That is:

1+ε＝1+α(T-T ₀)-k _TEε

Arrange:

$\mathrm{\Δl}=\frac{\mathrm{al}}{1+k_{T}E}\mathrm{\ΔT}$

Deformation causes speckle pattern interferometry:

If record plane, be X-Y plane, with reference to diffuse and change before object plane reflected light be superposed to:

$E(x,y)=a_0(x,y)e^{i{\mathrm{\φ}}_0(x,y)}+a_r(x,y)e^{i{\mathrm{\φ}}_r(x,y)}$

Wherein, α ₀for reference light amplitude, reference light phase place is φ ₀; a _rfor the amplitude of initial object light, initial object light phase place is φ _r.Light intensity I ₀for:

$I_0(x,y)=E(x,y)\·E^{*}(x,y)=a_0^2+a_r^2+2a_0{a}_r\cos ({\mathrm{\φ}}_0-{\mathrm{\φ}}_r)$

E in formula ^*(x, y) is the conjugation light wave complex amplitude of E (x, y).

If object does not produce absorption to light wave, the acoplanarity displacement Δ l (being Z-direction) due to body surface point, changes the light path of object light, so the phasic difference of object plane reflected light and reference light is on ccd video camera imaging plane

Light intensity I after deformation ₁become:

Adopt subtraction mode, and take absolute value into

when time, the light intensity after subtracting each other is 0.There is dark fringe;

Again because:

:

$\mathrm{\Δl}=\frac{\mathrm{n\λ}}{2}$

In conjunction with above-mentioned:

$\mathrm{\Δl}=\frac{\mathrm{al}}{1+k_{T}E}\mathrm{\ΔT}$

Temperature is:

$T=\frac{1+k_{T}E}{\mathrm{\α}1}\·\frac{\mathrm{n\λ}}{2}+T_0$

The present invention is making full use of on the basis of ESPI advantage, the model of structure interference fringe sum of series temperature, and by means of Matlab program, speckle pattern before and after heating is asked related operation and realized metering, realized the further innovation of high temperature test.

Should be understood that, for those of ordinary skills, can be improved according to the above description or convert, and all these improvement and conversion all should belong to the protection domain of claims of the present invention.

Claims (7)

1. the temperature measuring equipment based on speckle interference, it is characterized in that: comprise computing machine (9), green light semiconductor (1), laser beam expander (2), half-reflecting half mirror (3), with reference to diffuse surface (4), thermal source (6), optical filter (7) and ccd video camera (8), thermal source (6) is for giving test specimen to be measured (5) heating; Optical filter (7) is arranged on the shooting end of ccd video camera (8), the radiant light after being heated for filtering test specimen to be measured (5); Green light semiconductor (1) emitting laser is incident to half-reflecting half mirror (3) after beam expander (2) expands, after half-reflecting half mirror (3), obtain reflected light and transmitted light, described reflected light is incident to the front surface of test specimen to be measured (5), and produces object plane reflected light; The transmitted light obtaining after half-reflecting half mirror (3) is incident to reference to diffuse surface (4) and produces and diffuse, and reflexes to half-reflecting half mirror (3); Ccd video camera (8) diffuses and the speckle image of object plane reflected light in test specimen to be measured (5) front surface stack formation for taking, and the image signal output end of described ccd video camera (8) is connected with the picture signal input end of computing machine (9); Test specimen to be measured (5) for can produce the test specimen of deformation under heating condition; Computing machine (9) carries out image subtraction by the speckle image of test specimen to be measured (5) front surface before the speckle image of test specimen to be measured (5) front surface and the heating of acquisition after the heating obtaining, and obtains blackening fringe order n; By described blackening fringe order n substitution formula:

$T=\frac{1+k_{T}E}{\mathrm{\α}1}\·\frac{\mathrm{n\λ}}{2}+T_0$

Obtain the temperature T of test specimen to be measured;

In formula: α is the cubic expansion coefficient, k _tfor isothermal compressibility, E is elastic modulus, and l is the original thickness of test specimen to be measured (5), and λ is optical maser wavelength, T ₀for initial temperature.

2. the temperature measuring equipment based on speckle interference according to claim 1, is characterized in that, described optical filter (7) is the green glow filter plate corresponding with green light semiconductor (1) wavelength.

3. the temperature measuring equipment based on speckle interference according to claim 1 and 2, is characterized in that, computing machine is embedded with Matlab software in (9), and the speckle image that described Matlab software is used for treating test block (5) front surface carries out image processing.

4. the temperature measuring equipment based on speckle interference according to claim 1, is characterized in that, test specimen to be measured (5) is engine housing.

5. the temp measuring method based on the temperature measuring equipment based on speckle interference claimed in claim 1, is characterized in that: comprise the following steps:

Step 1, employing ccd video camera (8) are taken the speckle image of front test specimen to be measured (5) front surface of heating;

Step 2, employing thermal source (6) are treated test block (5) and are heated, and at test specimen to be measured (5), occur after deformation, adopt ccd video camera (8) to take the speckle image of rear test specimen to be measured (5) front surface of heating;

Before the heating that after the heating that step 3, employing computing machine (9) obtain step 2, the speckle image of test specimen to be measured (5) front surface and step 1 obtain, the speckle image of test specimen to be measured (5) front surface carries out image subtraction, obtains blackening fringe order n;

Step 4, the blackening fringe order n substitution formula that step 3 is obtained:

$T=\frac{1+k_{T}E}{\mathrm{\α}1}\·\frac{\mathrm{n\λ}}{2}+T_0$

Obtain the temperature T of test specimen to be measured;

In formula: α is the cubic expansion coefficient, k _tfor isothermal compressibility, E is elastic modulus, and l is the original thickness of test specimen to be measured (5), and λ is optical maser wavelength, T ₀for initial temperature.

6. the temp measuring method based on speckle interference according to claim 5, is characterized in that, the α of the cubic expansion coefficient described in step 4 passes through formula:

$\mathrm{\α}=\frac{1}{V}{\left(\frac{\∂V}{\∂T}\right)}_p,$

Obtain; In formula: V represents the volume of test specimen to be measured (5), and p represents pressure, T represents the temperature of test specimen to be measured (5).

7. the temp measuring method based on speckle interference according to claim 5, is characterized in that, the k of isothermal compressibility described in step 4 _tto pass through formula:

$k_T=-\frac{1}{V}{\left(\frac{\∂V}{\∂p}\right)}_T$

Obtain; In formula: V represents the volume of test specimen to be measured (5), and p represents pressure, T represents the temperature of test specimen to be measured (5).