CN102252755A - Online measurement apparatus and method of multispectral emissivity based on cylindrical lead reflector - Google Patents

Abstract

The invention relates to an online measuring device and method for multi-spectral emissivity based on a cylindrical front reflector, relating to an online measuring device and method for spectral emissivity. It solves the problems of low detection accuracy and easy damage to the measured material in the existing on-line measurement method of spectral emissivity. The bottom of the side wall of the cylindrical front reflector of the present invention is slidably connected to the guide rail; the optical aiming probe is suspended directly above the test piece, and its detection surface faces the upper surface of the test piece; the signal input end of the multispectral instrument passes through The optical fiber is connected with the signal output end of the optical aiming probe. The present invention realizes on-line measurement of emissivity by means of a cylindrical front reflector and an optical fiber multispectral instrument, realizes non-contact on-line measurement without destroying the surface of a test piece, and has high precision of measurement results. The invention is suitable for measuring the emissivity of objects.

Description

Multi-spectral emissivity online measurement device and method based on cylindrical front reflector

technical field

The invention relates to an online measuring device and method for spectral emissivity.

Background technique

The emissivity of an object is one of the basic parameters describing the thermal radiation properties of an object. It plays an important role in aerospace, military defense and industrial and agricultural production. For example, the thermal control, guidance and stealth of satellites, solar energy utilization, infrared heating and radiation temperature measurement are all inseparable from the emissivity of materials. The research on emissivity of materials at home and abroad has made great progress in recent years, and the problem of spectral emissivity measurement in the laboratory has been solved. However, modern military technology, material science and energy science urgently need equipment capable of online emissivity measurement, and there are few researches in this area.

At present, the most practical online measurement methods are digital conversion black body method and multi-spectral method, and other methods are difficult to meet the actual needs of online emissivity measurement. The basic principle of the conversion blackbody method is to drill a hole or add a reflector on the sample, so that the measured material approaches a blackbody or becomes a blackbody, so that the radiation power of the blackbody and the sample is measured with the same detector at the same temperature, so as to obtain the emission of the material. rate, this method will cause damage to the measured material, and the detection accuracy is low; the multi-spectral radiation temperature measurement method uses the measurement information of the radiance of the object under multiple spectra, and obtains the real temperature and spectral emission of the object after data processing Rate. Its advantages are: it can directly measure the emissivity, fast detection speed, portable, etc.; the disadvantage is: it is only suitable for small-sized samples, and it is easy to cause damage to the measured material. Some auxiliary tools need to be installed around the target.

Contents of the invention

The purpose of the present invention is to solve the problem that the detection accuracy of the existing spectral emissivity online measurement method is low and the measured material is easy to be damaged, thereby providing a multi-spectral emissivity online measurement device based on a cylindrical front reflector and method.

A multispectral emissivity online measurement device based on a cylindrical front reflector, which includes a multispectral instrument, an optical aiming probe, a cylindrical front reflector, a guide rail and a support frame, and the two ends of the guide rail are fixed on the support frame, and the guide rail The main body is arranged horizontally, and is located above the object to be tested; the cylindrical front reflector is a lower opening structure, and the top surface of the cylindrical front reflector has a light radiation hole, and the cylindrical front reflector The spherical bottom of the ball is slidingly connected with the guide rail; the optical aiming probe is suspended directly above the test piece, and the detection surface of the optical aiming probe faces the upper surface of the test piece; the detection surface of the optical aiming probe is connected to the upper surface of the test piece The distance is greater than the height of the cylindrical front reflector; the signal input end of the multispectral instrument is connected with the signal output end of the optical aiming probe.

Based on the multi-spectral emissivity online measurement method based on the cylindrical front reflector of the above-mentioned device, it is realized by the following steps:

Step 1. Translate the cylindrical front reflector to the top of the test piece, use the optical aiming probe to align and detect the radiation beam of the light radiation hole on the top surface of the cylindrical front reflector,

According to the formula:

L ₁ (λ, T) = f(ε(λ, T))L(λ, T)

Obtain the radiance L ₁ (λ, T) perpendicular to the plane direction of the test piece, where: f(ε(λ, T)) is the effective emissivity function of the cylindrical front reflector cavity; L(λ, T) is the radiance of the blackbody on the surface of the test piece under the same conditions;

Step 2. Translate the cylindrical front reflector out of the detection range of the detection surface of the optical aiming probe, use the optical aiming probe to directly detect the radiation beam on the upper surface of the test piece, and according to the formula:

L ₂ (λ, T) = ε(λ, T)L(λ, T)

Obtain the radiance L ₂ (λ, T) perpendicular to the direction of the plane where the test piece is located, where ε(λ, T) is the normal spectral emissivity of the surface of the test piece, and L(λ, T) is the The radiance of a blackbody on the surface under the same conditions;

Step 3, according to the formula:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$

根据公式：Obtain the voltage output value of the multispectral instrument at the wavelength _λi under the condition of adding a cylindrical front reflector in the optical path

According to the formula:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$

Obtain the voltage output value of the multispectral instrument at the wavelength _λi without adding a cylindrical front reflector in the optical path

In the formula: R(λ _i ) is the spectral response function of the fiber-optic multispectral instrument, and R(λ _i ) is a certain value for any wavelength λ _i ;

Step 4, according to the formula

${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$

The emissivity ε(λ, T) of the test piece 4 is obtained.

Beneficial effects: the present invention realizes on-line measurement of emissivity by means of a cylindrical front reflector and a fiber-optic multispectral instrument, realizes non-contact on-line measurement without damaging the surface of the test piece, has high precision of measurement results, is easy to maintain, and is operable Strong.

Description of drawings

Fig. 1 is a schematic diagram of the results of the device of the present invention; Fig. 2 is a sectional view taken along the line A-A of Fig. 1 .

Detailed ways

Specific Embodiments 1. This specific embodiment is described in conjunction with Fig. 1 and Fig. 2. The multispectral emissivity online measuring device based on a cylindrical front reflector includes a multispectral instrument 1, an optical aiming probe 3, a cylindrical front reflector The reflector 5, the guide rail 6 and the support frame, the two ends of the guide rail 6 are fixed on the support frame, the main body of the guide rail is arranged horizontally, and is located above the test piece 4; the cylindrical front reflector 5 is a lower opening structure, and the circular The top surface of the cylindrical front reflector 5 has a light radiation hole, and the spherical bottom of the cylindrical front reflector 5 is slidably connected with the guide rail 6; the optical aiming probe 3 is suspended directly above the test piece 4, and The detection surface of the optical aiming probe 3 faces the upper surface of the test piece 4; the distance between the detection surface of the optical aiming probe 3 and the upper surface of the test piece 4 is greater than the height of the cylindrical front reflector 5; the multispectral instrument 1 The signal input end of the optical aiming probe 3 is connected with the signal output end. The guide rail 6 can make the cylindrical front reflector 5 move in two dimensions.

The optical aiming probe 3 in the present invention is aimed at the light radiation hole of the cylindrical front reflector 5 and the test object 4 so that the multispectral instrument 1 can measure the radiance of the test object 4 under different conditions.

Specific embodiment two, the difference between this specific embodiment and the multi-spectral emissivity online measurement device based on the cylindrical front reflector described in the specific embodiment one is that it also includes an optical fiber 2, a signal input end of the multispectral instrument 1 It is connected to the signal output end of the optical aiming probe 3 through the optical fiber 2 .

Specific embodiment three. The difference between this specific embodiment and the multi-spectral emissivity online measurement device based on the cylindrical front reflector described in the specific embodiment one or two is that it also includes a stepping motor, and the stepping The motor is used to drive the cylindrical front reflector 5 to translate along the length direction of the guide rail.

Embodiment four, the difference between this embodiment and the multi-spectral emissivity online measurement device based on the cylindrical front reflector described in embodiment three is that it also includes a computer, and the signal output terminal of the multi-spectrometer 1 is connected to the Connect to the signal input terminal of the computer.

Embodiment 5. The difference between this embodiment and the cylindrical front reflector-based multispectral emissivity online measuring device described in Embodiment 1, 2 or 4 is that the multispectral instrument 1 is a fiber optic multispectral instrument.

The multi-spectrometer 1 in the present invention collimates and disperses the radiant energy transmitted by the optical fiber 2 into multiple parallel light beams with different wavelengths and different angles by a spectroscopic system, which are imaged on the focal plane and absorbed by the multi-element detector array. After the detector array completes the conversion of radiation energy into electrical energy, the collected data is sent to the computer for subsequent processing through the electrical system composed of preamplifier and sample holder.

Embodiment 6. The difference between this embodiment and the multi-spectral emissivity online measuring device based on the cylindrical front reflector described in Embodiment 5 is that the cylindrical front reflector 5 has a polished inner surface. Processed cylindrical front reflector.

Specific embodiment seven, based on the multi-spectral emissivity online measurement method based on the cylinder front reflector described in the specific embodiment one, it is realized by the following steps:

Step 1. Translate the cylindrical front reflector 5 directly above the test piece 4, and use the optical aiming probe 3 to detect the radiation beam of the light radiation hole on the top surface of the cylindrical front reflector 5,

According to the formula:

L ₁ (λ, T) = f(ε(λ, T))L(λ, T)

Obtain the radiance L ₁ (λ, T) perpendicular to the plane direction of the test piece 4, in the formula: f(ε(λ, T)) is the effective emissivity function of the cylindrical front reflector 5 cavities; L( λ, T) is the radiance of the blackbody on the surface of the test piece 4 under the same conditions;

Step 2. Translate the cylindrical front reflector 5 out of the detection range of the detection surface of the optical aiming probe 3, and use the optical aiming probe 3 to directly detect the radiation beam on the upper surface of the test piece 4, and according to the formula:

L ₂ (λ, T) = ε(λ, T)L(λ, T)

Obtain the radiance L ₂ (λ, T) perpendicular to the direction of the plane where the test piece is located, where ε(λ, T) is the normal spectral emissivity of the surface of the test piece, and L(λ, T) is the 4 The radiance of the blackbody on the surface under the same conditions;

Step 3, according to the formula:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$

Obtain the voltage output value of the multispectral instrument 1 at the wavelength _λi when the cylindrical front reflector 5 is added to the optical path

According to the formula:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$

Obtain the voltage output value of the multispectral instrument 1 at the wavelength _λi under the condition that the cylindrical front reflector 5 is not added to the optical path

In the formula: R(λ _i ) is the spectral response function of the fiber-optic multispectral instrument, and R(λ _i ) is a certain value for any wavelength λ _i ;

Step 4, according to the formula

${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$

The emissivity ε(λ, T) of the test piece 4 is obtained.

Claims (7)

1. The multi-spectral emissivity online measurement device based on the cylindrical front reflector is characterized in that: it includes a multispectral instrument (1), an optical aiming probe (3), a cylindrical front reflector (5), a guide rail (6) and a support frame, the two ends of the guide rail (6) are fixed on the support frame, the main body of the guide rail is arranged horizontally, and is positioned above the piece to be tested (4); the cylindrical front reflector (5) is a lower opening structure, the top surface of the cylindrical front reflector (5) has a light radiation hole, and the spherical bottom of the cylindrical front reflector (5) is slidingly connected with the guide rail (6); the optical aiming probe (3) Hanging directly above the test piece (4), and the detection surface of the optical aiming probe (3) faces the upper surface of the test piece (4); the detection surface of the optical aiming probe (3) is in contact with the test piece (4) ) is greater than the height of the cylindrical front reflector (5); the signal input end of the multispectral instrument (1) is connected to the signal output end of the optical aiming probe (3). 2. the multispectral emissivity on-line measuring device based on cylindrical front reflector according to claim 1, is characterized in that it also comprises optical fiber (2), and the signal input end of multispectral instrument (1) passes through optical fiber (2) ) is connected to the signal output end of the optical aiming probe (3). 3. The multi-spectral emissivity online measuring device based on a cylindrical front reflector according to claim 1 or 2, characterized in that it also includes a stepping motor, and the stepping motor is used to drive the cylindrical front reflector Set the reflector (5) to translate along the length direction of the guide rail. 4. the multispectral emissivity online measuring device based on cylindrical front reflector according to claim 3, is characterized in that it also comprises computer, and the signal output end of multispectral instrument (1) is connected with the signal input end of computer . 5. The multispectral emissivity online measuring device based on a cylindrical front reflector according to claim 1, 2 or 4, characterized in that the multispectral instrument (1) is a fiber optic multispectral instrument. 6. the multi-spectral emissivity on-line measuring device based on the cylindrical front reflector according to claim 5, characterized in that the cylindrical front reflector (5) is a cylinder whose inner surface is polished type front reflector. 7. based on the multi-spectral emissivity online measurement method based on the cylindrical front reflector described in claim 1, it is characterized in that: it is realized by the following steps: Step 1. Translate the cylindrical front reflector (5) directly above the test piece (4), and use the optical aiming probe (3) to align and detect the top surface of the cylindrical front reflector (5). the radiation beam of the light radiation aperture, According to the formula: L ₁ (λ, T) = f(ε(λ, T))L(λ, T) Obtain the radiance L ₁ (λ, T) perpendicular to the direction of the plane where the test piece (4) is located, where: f(ε(λ, T)) is defined as the effective cavity of the cylindrical front reflector (5) Emissivity function, where ε (λ, T) is the normal spectral emissivity of the surface of the test piece, which is a function of wavelength λ and temperature T; L (λ, T) is the surface of the test piece (4) under the same conditions The radiance of the lower black body; Step 2: Translating the cylindrical front reflector (5) out of the detection range of the detection surface of the optical aiming probe (3), using the optical aiming probe (3) to directly detect the radiation beam on the upper surface of the test piece (4), and According to the formula: L ₂ (λ, T) = ε(λ, T)L(λ, T) Obtain the radiance L ₂ (λ, T) perpendicular to the plane direction of the test piece, where ε(λ, T) is the normal spectral emissivity of the surface of the test piece; Step 3, according to the formula: ${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$ Obtain the voltage output value of the multispectral instrument (1) at the wavelength _λi when the cylindrical front reflector (5) is added to the optical path

According to the formula: ${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$ Obtain the voltage output value of the multispectral instrument (1) at the wavelength _λi under the condition that the cylindrical front reflector (5) is not added to the optical path

In the formula: R(λ _i ) is the spectral response function of the fiber-optic multispectral instrument, and R(λ _i ) is a certain value for any wavelength λ _i ; Step 4, according to the formula ${\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; )</span>$ Obtain the emissivity ε(λ, T) of the test piece (4).