CN102735357A - 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

Based on the temperature measuring equipment of speckle interference and adopt the temp measuring method of this device

Technical field

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

Background technology

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

The speckle interference measuring technique is a kind of optical measuring technique that is at first proposed by J.M.Burch and J.T.Kardki the end of the sixties; Have noncontact, measuring accuracy high, to environment shockproof require low, can under Mingguang City, operate, can carry out characteristics such as measurement of full field, thereby be widely used in optically roughness surperficial deformation measurement and Non-Destructive Testing field.Along with computer technology, electronic technology and development of digital image; Formed ESPI measuring technique (electronic speckle pattern interferometry; Be called for short ESPI), it has real-time process information, shows interference fringe, quick and convenient, low and can realize advantage such as striped automatic measurement to the shockproof requirement of working environment in real time.

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 be lower for the accuracy that solves the temperature-measuring results that existing temp measuring method obtains, temperature-measuring range is less, the slow problem of thermometric, thereby provide a kind of based on speckle interference temperature measuring equipment and adopt 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 used for heating to test specimen to be measured (5); Optical filter (7) is installed in the shooting end of ccd video camera (8), is used for the radiant light after filtering test specimen to be measured (5) is heated; Green light semiconductor (1) emitting laser is incident to half-reflecting half mirror (3) after beam expander (2) expands bundle, behind half-reflecting half mirror (3), obtain reflected light and transmitted light, and said reflected light is incident to the front surface of test specimen to be measured (5), and produces the object plane reflected light; The transmitted light that behind half-reflecting half mirror (3), obtains is incident to reference to diffuse surface (4) generation and diffuses, and reflexes to half-reflecting half mirror (3); Ccd video camera (8) is used for shooting and diffuses and the speckle image of object plane reflected light in test specimen to be measured (5) front surface stack formation, and the image signal output end of said ccd video camera (8) is connected with the picture signal input end of computing machine (9); Test specimen to be measured (5) is under heating condition, to produce the test specimen of deformation; After the heating that computing machine (9) will obtain before the heating of the speckle image of test specimen to be measured (5) front surface and acquisition the speckle image of test specimen to be measured (5) front surface carry out image subtraction, obtain blackening fringe order n; With said 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 the formula: α is the cubic expansion coefficient, k _TBe isothermal compressibility, E is an elastic modulus, and l is the original thickness of test specimen to be measured (5), and λ is an optical maser wavelength, T ₀Be initial temperature.

Described temperature measuring equipment based on speckle interference, said optical filter (7) are and the corresponding green glow filter plate of green light semiconductor (1) wavelength.

Described temperature measuring equipment based on speckle interference, computing machine is embedded with Matlab software in (9), and the speckle image that said Matlab software is used to treat test block (5) front surface carries out Flame Image Process.

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

The temp measuring method of described temperature measuring equipment based on speckle interference may further comprise the steps:

The speckle image of test specimen to be measured (5) front surface before step 1, employing ccd video camera (8) are taken and heated;

Step 2, employing thermal source (6) are treated test block (5) and are heated, after deformation takes place in test specimen to be measured (5), and the speckle image of test specimen to be measured (5) front surface after employing ccd video camera (8) is taken and heated;

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

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

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

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

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

Described temp measuring method based on speckle interference, isothermal compressibility k described in the step 4 _TBe through formula:

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

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

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

Description of drawings

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

It is back from face deformation synoptic diagram that Fig. 2 is that 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 Flame Image Process.

Embodiment

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

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 used for to test specimen 5 heating to be measured; Optical filter 7 is installed in the shooting end of ccd video camera 8, is used for the radiant light after filtering test specimen 5 to be measured is heated; System's emitting laser is incident to half-reflecting half mirror 3 after beam expander 2 expands bundle, behind half-reflecting half mirror 3, obtain reflected light and transmitted light, and said reflected light is incident to the front surface of test specimen 5 to be measured, and produces the object plane reflected light; The transmitted light that behind half-reflecting half mirror 3, obtains is incident to reference to diffuse surface 4 generations and diffuses, and reflected back half-reflecting half mirror 3; Ccd video camera 8 is used to take the speckle image that diffuses and form in the stack of test specimen 5 front surfaces to be measured with the object plane reflected light; Its speckle image is as shown in Figure 3 before test specimen 5 deformation to be measured; Its speckle image is as shown in Figure 4 after test specimen 5 deformation to be measured; The image signal output end of said ccd video camera 8 and computing machine 9, its thickness as shown in Figure 2 is L before test specimen to be measured 5 heating, its thickness as shown in Figure 2 was that the picture signal input end of L+ Δ L connects after test specimen 5 to be measured was heated; Test specimen 5 to be measured is under heating condition, to produce the test specimen of deformation.

Embodiment two:

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

Embodiment three:

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

Embodiment four;

The difference of the described temperature measuring equipment based on speckle interference of this embodiment and embodiment one, two or three is; Be embedded with Matlab software in the computing machine 9, the speckle image that said Matlab software is used to treat test block 5 front surfaces carries out Flame Image Process.

Embodiment five:

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

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

Embodiment six:

Based on the temp measuring method based on speckle interference of 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 the heating, obtain speckle image as shown in Figure 3.

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

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

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

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

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

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

The k of isothermal compressibility described in the step 4 _TBe through formula:

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

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

Among 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]

Then:

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

That is:

1+ε＝1+α(T-T ₀)-k _Tp

V wherein ₀Represent the preceding volume of test specimen 5 heating to be measured, V representes the volume after test specimen 5 heating to be measured, and α is the cubic expansion coefficient, k _TBe isothermal compressibility, p representes pressure, T ₀Represent the preceding temperature of test specimen 5 heating to be measured, T representes test specimen 5 heated temperatures to be measured, and ε representes the relative deformation amount of test specimen 5 to be measured.

For the elastic body tensile deformation:

$\frac{F}{S}=E\frac{\mathrm{\Δl}}{l}$

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

After the distortion be:

p＝Eε

That is:

1+ε＝1+α(T-T ₀)-k _TEε

Put in order:

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

Deformation causes speckle pattern interferometry:

If the record plane is an X-Y plane, be superposed to reference to diffusing and changing preceding object plane reflected light:

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

Wherein, α ₀Be the reference light amplitude, the reference light phase place is φ ₀a _rBe the amplitude of initial thing light, initial thing light phase is φ _rLight intensity I ₀For:

$I_0(x,y)=E(x,y)\&CenterDot;E^{*}(x,y)=a_0^2+a_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HSA00000740527100011.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+2a_0{a}_r\cos ({\mathrm{\&phi;}}_0-{\mathrm{\&phi;}}_r)$

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

If object does not produce absorption to light wave; Because the acoplanarity displacement Δ l (being Z-direction) of body surface point; The light path of thing light is changed, so the phasic difference of object plane reflected light and reference light is

on the ccd video camera imaging plane

Light intensity I after the deformation ₁Become:

Adopt subtraction mode, and take absolute value into

during as

, the light intensity after subtracting each other is 0.Dark fringe appears;

Again because:

Then:

$\mathrm{\&Delta;l}=\frac{\mathrm{n\&lambda;}}{2}$

In conjunction with above-mentioned:

$\mathrm{\&Delta;l}=\frac{\mathrm{al}}{1+k_{T}E}\mathrm{\&Delta;T}$

Then temperature is:

$T=\frac{1+k_{T}E}{\mathrm{\&alpha;}1}\&CenterDot;\frac{\mathrm{n\&lambda;}}{2}+T_0$

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

Should be understood that, concerning those of ordinary skills, can improve or conversion, and all these improvement and conversion all should belong to the protection domain of accompanying claims of the present invention according to above-mentioned explanation.

Claims (7)

1. 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 used for heating to test specimen to be measured (5); Optical filter (7) is installed in the shooting end of ccd video camera (8), is used for the radiant light after filtering test specimen to be measured (5) is heated; Green light semiconductor (1) emitting laser is incident to half-reflecting half mirror (3) after beam expander (2) expands bundle, behind half-reflecting half mirror (3), obtain reflected light and transmitted light, and said reflected light is incident to the front surface of test specimen to be measured (5), and produces the object plane reflected light; The transmitted light that behind half-reflecting half mirror (3), obtains is incident to reference to diffuse surface (4) generation and diffuses, and reflexes to half-reflecting half mirror (3); Ccd video camera (8) is used for shooting and diffuses and the speckle image of object plane reflected light in test specimen to be measured (5) front surface stack formation, and the image signal output end of said ccd video camera (8) is connected with the picture signal input end of computing machine (9); Test specimen to be measured (5) is under heating condition, to produce the test specimen of deformation; After the heating that computing machine (9) will obtain before the heating of the speckle image of test specimen to be measured (5) front surface and acquisition the speckle image of test specimen to be measured (5) front surface carry out image subtraction, obtain blackening fringe order n; With said blackening fringe order n substitution formula:

$T=\frac{1+k_{T}E}{\mathrm{\&alpha;}1}\&CenterDot;\frac{\mathrm{n\&lambda;}}{2}+T_0$

Obtain the temperature T of test specimen to be measured;

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

2. the temperature measuring equipment based on speckle interference according to claim 1 is characterized in that, said optical filter (7) is and the corresponding green glow filter plate of 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 said Matlab software is used to treat test block (5) front surface carries out Flame Image Process.

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

5. based on the temp measuring method of the described temperature measuring equipment based on speckle interference of claim 1, it is characterized in that: may further comprise the steps:

The speckle image of test specimen to be measured (5) front surface before step 1, employing ccd video camera (8) are taken and heated;

Step 2, employing thermal source (6) are treated test block (5) and are heated, after deformation takes place in test specimen to be measured (5), and the speckle image of test specimen to be measured (5) front surface after employing ccd video camera (8) is taken and heated;

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

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

$T=\frac{1+k_{T}E}{\mathrm{\&alpha;}1}\&CenterDot;\frac{\mathrm{n\&lambda;}}{2}+T_0$

Obtain the temperature T of test specimen to be measured;

In the formula: α is the cubic expansion coefficient, k _TBe isothermal compressibility, E is an elastic modulus, and l is the original thickness of test specimen to be measured (5), and λ is an optical maser wavelength, T ₀Be 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 the step 4 is through formula:

$\mathrm{\&alpha;}=\frac{1}{V}{\left(\frac{\&PartialD;V}{\&PartialD;T}\right)}_p,$

Obtain; In the formula: V representes the volume of test specimen to be measured (5), and p representes pressure, and T representes 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 the step 4 _TBe through formula:

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

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

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