Method for measuring radiation characteristics of material

Abstract

The invention relates to a method for measuring the radiation characteristic of a material, and solves the problem of low measurement precision of the radiation characteristic of the material at a relatively high temperature in the prior art. Comprising the following steps that a tested material is placed in a temperature control device, the center of the tested material directly faces a radiation opening of the temperature control device, and the tested material is set to a set temperature; the tested material is a structural material or a window material; the positions of the measured material, the standard black body and the Fourier spectrum radiometer are adjusted, so that radiation signals emitted by the measured material and the standard black body can be respectively received by the Fourier spectrum radiometer, and spectrum radiation quantity values are obtained through measurement; based on the measured material and the spectral radiation quantity value emitted by the standard black body, the radiation characteristic of the material is calculated by using a processor; comprise the normal spectral emissivity of the structural material, the radiation transmissivity of the window material and the normal spectral emissivity of the window material calculated based on the radiation transmissivity. And accurate measurement of the radiation characteristic of the material at high temperature is realized.

Description

Technical Field

[0001] The invention relates to the technical field of optical measurement, and in particular to a method for measuring radiation characteristics of a material. Background Art

[0002] Emissivity is a physical quantity that characterizes the radiation characteristics of the surface of various materials. It is defined as the ratio of the radiation capacity of the material surface to the radiation capacity of a black body at the same temperature. Emissivity testing has a broad application background in engineering and scientific research, such as in the aerospace industry and national defense science research.

[0003] The measurement of emissivity can be classified into calorimetry, reflection, energy, multi-wavelength and other methods according to the measurement method. The advantage of the calorimetry method is that it can not only calculate the emissivity but also other thermophysical parameters based on the heat transfer theory; its disadvantage is that the measurement environment requirements are extremely strict (theoretically it should be an adiabatic environment), and poor control will lead to large errors, so this method is rarely used to measure emissivity alone. The reflection method is based on the law of conservation of energy and Kirchhoff's law. As long as the radiation energy of known intensity is projected onto the surface of the opaque sample to be measured and the surface reflected energy is measured with a reflectometer, the reflectivity of the sample can be obtained and the emissivity can be calculated.

[0004] Semi-transparent media are widely used in scientific fields such as energy and power, aerospace, information and communication. With the development of national defense technology and materials science, the demand for the radiation characteristics of semi-transparent materials is becoming more and more urgent. At present, there are relatively few studies on the semi-transparent spectral emissivity under high temperature conditions at home and abroad. In the process of measuring the spectral emissivity of semi-transparent materials, since the measured materials are highly transparent to energy in certain wavelength ranges, heating will affect the measurement of the sample's spectral emissivity.

[0005] The measurement methods of material transmittance are divided into single optical path method and dual optical path method according to the optical path structure. The advantages of the single optical path method are simple structure and low cost, and the disadvantages are that it is not convenient to use and the measurement results are easily affected by the instability of the light source and the change of detector sensitivity. The dual optical path method can effectively reduce the influence of the instability of the light source and the change of detector sensitivity on the measurement results, but its structure is complex. Both the single optical path measurement method and the dual optical path measurement method are measurement methods based on the monochromator system. The improvement of their spectral resolution is limited by the performance of the monochromator. With the improvement of spectral resolution, the spectral band becomes narrower, which makes the spectral signal weaker and the measurement time becomes longer accordingly. In order to solve these problems, the Fourier transform spectrometer has emerged. The spectrometer has the advantages of wide spectral range, high spectral resolution, and fast measurement speed. It is more and more widely used in the field of infrared spectrum measurement.

[0006] The above methods can measure the spectral transmittance of infrared window materials at room temperature and achieve high accuracy. For transmittance measurement under higher temperature conditions, there are fewer related research results. Summary of the invention

[0007] In view of the above analysis, an embodiment of the present invention aims to provide a method for measuring radiation characteristics of a material, so as to solve the problem of low accuracy in measuring radiation characteristics of a material at a relatively high temperature.

[0008] The purpose of the present invention is mainly achieved through the following technical solutions:

[0009] The present invention provides a method for measuring the radiation characteristics of a material, comprising the following steps:

[0010] The material to be tested is placed in a temperature control device, with the center of the material to be tested facing the radiation port of the temperature control device, and is set to a set temperature; the material to be tested is a structural material or a window material;

[0011] Adjusting the positions of the material to be tested, the standard black body and the Fourier spectrum radiometer so that the radiation signals emitted by the material to be tested and the standard black body can be respectively received by the Fourier spectrum radiometer and measured to obtain the spectral radiation value;

[0012] Based on the spectral radiation values ​​emitted by the material under test and the standard black body, the radiation characteristics of the material are calculated using a processor; including: the normal spectral emissivity of the structural material, the radiation transmittance of the window material, and the normal spectral emissivity of the window material calculated based on the radiation transmittance.

[0013] Furthermore, when measuring the normal spectral emissivity of a structural material, it includes:

[0014] Placing the standard black body opposite to one radiation port of the temperature control device, and closing the other radiation port;

[0015] Setting the standard blackbody temperature to be consistent with the temperature of the temperature control device;

[0016] Swinging the folding and swinging mirror between the standard black body and the temperature control device to switch the radiation signals emitted by the structural material and the standard black body and transmit them to the Fourier spectroradiometer, and alternately measuring the spectral radiation value of the structural material and the spectral radiation value of the standard black body;

[0017] The normal spectral emissivity of the structural material is obtained based on the spectral radiation value of the structural material and the spectral radiation value of the standard black body.

[0018] Furthermore, based on the spectral radiation value of the structural material and the spectral radiation value of the standard black body, the normal spectral emissivity of the structural material is calculated using the following formula:

[0019]

[0020] Where ε(λ) is the normal spectral emissivity of the structural material; M sample (λ) is the spectral radiation value of the structural material; M B (λ) is the spectral radiation value of the standard black body; ε B (λ) is the normal spectral emissivity of the standard black body.

[0021] Furthermore, the spectral radiation of the structural material is emitted to the folding and swinging mirror through the cold shield.

[0022] Furthermore, when measuring the spectral transmittance of the window material, it includes:

[0023] The temperature control device is arranged between the standard black body and the Fourier spectroradiometer;

[0024] Setting the standard black body temperature to T1 and measuring the spectral radiation value transmitted through the temperature control device;

[0025] Taking out the window material, keeping the standard black body temperature at T1, and using the Fourier spectroradiometer to directly measure the spectral radiation value of the standard black body;

[0026] Setting the standard black body temperature to T2 and measuring the spectral radiation value transmitted through the temperature control device;

[0027] Taking out the window material, keeping the standard black body temperature at T2, and using the Fourier spectroradiometer to directly measure the spectral radiation value of the standard black body;

[0028] The spectral transmittance of the window material is obtained based on the spectral radiation values ​​of the standard black body and the temperature control device measured when the standard black body temperature is T1 and when the temperature is T2.

[0029] Furthermore, based on the spectral radiation values ​​of the standard black body and the temperature control device measured when the standard black body temperature is T1 and when the temperature is T2, the spectral transmittance of the window material is calculated using the following formula:

[0030]

[0031] Where τ(λ) is the spectral transmittance of the window material; M C1 (λ) is the spectral radiation value transmitted through the window material when the standard black body is set at temperature T1; M C2 (λ) is the spectral radiation value transmitted through the window material when the standard black body is set at temperature T2; M T1 (λ) is the spectral radiation measurement value of the standard black body at temperature T1; M T2(λ) is the spectral radiation measurement value of the standard black body at temperature T2.

[0032] Furthermore, when measuring the spectral radiation value transmitted through the temperature control device, the spectral radiation emitted by the standard black body passes through the first cold shield, the temperature control device, the second cold shield in sequence to the Fourier spectroradiometer.

[0033] Furthermore, when measuring the normal spectral emissivity of the window material, it includes:

[0034] Pre-measuring the spectral transmittance of the window material;

[0035] The temperature control device is arranged between the reflector and the Fourier spectroradiometer to measure the spectral radiation value of the window material;

[0036] Setting the standard blackbody temperature to be consistent with the temperature of the temperature control device;

[0037] Placing the standard black body in front of the Fourier spectroradiometer to measure the spectral radiation value of the standard black body;

[0038] Based on the spectral transmittance of the window material, the spectral radiation value of the window material and the spectral radiation value of the standard black body, the normal spectral emissivity of the window material is obtained.

[0039] Furthermore, based on the spectral radiation value of the window material and the spectral radiation value of the standard black body, the normal spectral emissivity of the window material is calculated using the following formula:

[0040]

[0041] Where ε(λ) is the normal spectral emissivity of the window material; M c (λ) is the spectral radiation value of the window material; M B (λ) is the spectral radiation value of the standard black body; ε B (λ) is the normal spectral emissivity of the standard black body; ρ(λ) is the reflectivity of the reflector; τ(λ) is the spectral transmittance of the window material.

[0042] Furthermore, the spectral radiation of the window material is emitted to the reflector and the Fourier spectroradiometer respectively through the first cold shield and the second cold shield.

[0043] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0044] 1. The test method of the present invention can accurately measure the radiation characteristics of materials under high temperature conditions, wherein the measurement band range is 3μm~5μm, 8μm~14μm, the measurement angle range is ±10°, the temperature range is 300K~800K, and the measurement uncertainty is ≤6% (emissivity uncertainty: 4% for opaque materials, 6% for transparent materials; transmittance uncertainty: 4%).

[0045] 2. The measuring method used in the present invention can measure three radiation characteristics of two materials by adjusting the positions of the measured material, the standard black body and the Fourier spectroradiometer, which is easy to operate and highly practical.

[0046] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0048] Figure 1 This is a schematic flow chart of a method for measuring radiation characteristics of a material in an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the flow chart of the method for measuring the normal spectral emissivity of a structural material in an embodiment of the present invention;

[0050] Figure 3 This is a schematic flow chart of a method for measuring normal spectral transmittance of a window material in an embodiment of the present invention;

[0051] Figure 4 Schematic diagram of the process of measuring the normal spectral emissivity of window materials in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0053] A specific embodiment of the present invention discloses a method for measuring the radiation characteristics of a material, such as Figure 1 As shown, the following steps are included:

[0054] Step S1, placing the material to be tested in a temperature control device, with the center of the material to be tested facing the radiation port of the temperature control device, and setting the temperature to a set value; the material to be tested is a structural material or a window material;

[0055] Specifically, structural materials are materials used to manufacture load-bearing components based on mechanical properties. Since they are opaque materials, the radiation property that needs to be measured for structural materials is their emissivity.

[0056] Furthermore, the window material is generally used as the material of the receiving part of the instrument, which can be used to isolate the external environment, protect the internal components, and has a high transmittance to light of a specific wavelength or band, playing the role of a window. Therefore, the radiation properties that need to be measured for the window material are emissivity and transmittance.

[0057] Furthermore, the temperature control device is a hollow cubic structure, the material to be tested is placed in the middle sample slot, electric heating is used around the material to uniformly heat the material to be tested, and a water-cooling interlayer is designed to measure the radiation characteristics of the material to be tested at different temperatures.

[0058] Specifically, the temperature control device can control the temperature of the material at room temperature to 600° C. The material to be tested is heated and kept warm in the temperature control device so that the material reaches thermal equilibrium.

[0059] Specifically, the temperature control device includes two radiation ports, the material to be tested is placed in the temperature control device, and the two radiation ports correspond to the middle areas of the front and back sides of the material to be tested.

[0060] Step S2, adjusting the positions of the material to be tested, the standard black body and the Fourier spectrum radiometer so that the radiation signals emitted by the material to be tested and the standard black body can be respectively received by the Fourier spectrum radiometer and measured to obtain the spectral radiation value;

[0061] Specifically, blackbody radiation refers to the radiation emitted by an ideal radiator, which emits the maximum amount of radiation at a specific temperature and wavelength. In order to study the laws of thermal radiation that are independent of the specific physical properties of the substance, physicists have defined an ideal object, the black body, as a standard object for thermal radiation research. The standard black body is a blackbody radiation source that provides standard infrared radiation, has a high emissivity, and precise temperature control accuracy.

[0062] Furthermore, the Fourier spectroradiometer is an instrument for analyzing and identifying the composition of a substance. It uses the interaction between matter and radiation to measure the absorption of the substance at different wavelengths, thereby obtaining the spectral radiation of the substance.

[0063] Step S3, based on the spectral radiation values ​​emitted by the material under test and the standard black body, use a processor to calculate the radiation characteristics of the material; including: the normal spectral emissivity of the structural material, the radiation transmittance of the window material, and the normal spectral emissivity of the window material calculated based on the radiation transmittance.

[0064] Specifically, the processor calculates the radiation characteristics of the material through a mathematical formula based on the spectral radiation values ​​emitted by the material under test and the standard black body. It should be noted that when measuring the normal spectral emissivity of the window material, the radiation transmittance of the window material needs to be measured in advance.

[0065] Furthermore, when measuring the normal spectral emissivity of a structural material, such as Figure 2 As shown, the measurement steps include the following:

[0066] Step S101, placing the standard black body opposite to one radiation port of the temperature control device, and closing the other radiation port;

[0067] Step S102, setting the standard black body temperature to be consistent with the temperature of the temperature control device;

[0068] Step S103, swinging the folding and swinging mirror between the standard black body and the temperature control device to switch the radiation signals emitted by the structural material and the standard black body to the Fourier spectroradiometer, and alternately measuring the spectral radiation value of the structural material and the spectral radiation value of the standard black body;

[0069] Step S104: obtaining the normal spectral emissivity of the structural material based on the spectral radiation value of the structural material and the spectral radiation value of the standard black body.

[0070] Specifically, the radiation port of the standard black body is placed opposite to the opened radiation port of the temperature control device, and the folding and swinging mirror is placed between the standard black body and the temperature control device, swinging between two fixed points to reflect the radiation signal emitted by the standard black body and the structural material into the Fourier spectroradiometer.

[0071] Furthermore, based on the spectral radiation value of the structural material and the spectral radiation value of the standard black body, the normal spectral emissivity of the structural material can be obtained according to the reflectivity calculation formula:

[0072]

[0073] Where ε(λ) is the normal spectral emissivity of the structural material; M sample (λ) is the spectral radiation value of the structural material; M B (λ) is the spectral radiation value of the standard black body.

[0074] Considering that the standard black body is actually only an approximate ideal black body, the emissivity of the standard black body cannot reach 1. In this case, if the emissivity of the standard black body is calculated as 1, the measured radiation characteristics of the measured material will be higher than the true value. When calculating the radiation characteristics, the true emissivity of the standard black body must be considered. The true emissivity of the standard black body has been measured as an equipment indicator when manufacturing the standard black body device.

[0075] Therefore, using a processor, the normal spectral emissivity of the structural material is calculated by the following formula:

[0076]

[0077] Among them, ε B (λ) is the normal spectral emissivity of the standard black body.

[0078] Furthermore, the temperature control device will generate environmental radiation during the heating process. In order to avoid the influence of environmental radiation on the measurement accuracy, a cold shielding device is placed in front of the radiation port of the temperature control device. The device is a water-cooled aperture and is polished internally with an extremely low emissivity, which largely eliminates the adverse effects of environmental radiation on the measurement. The cold shielding device is connected to the water-cooled and heating device through insulating material, eliminating the influence of the cold shielding device on the temperature control accuracy of the water-cooled and heating device.

[0079] Specifically, the cold shield is placed in front of the opened radiation port of the temperature control device, and the spectral radiation of the structural material is emitted to the folding and oscillating mirror through the cold shield.

[0080] Furthermore, when measuring the spectral transmittance of the window material, such as Figure 3 As shown, the following steps are included:

[0081] Step S201, setting the temperature control device between the standard black body and the Fourier spectroradiometer;

[0082] Step S202, setting the standard black body temperature to T1 and measuring the spectral radiation value transmitted through the temperature control device; optionally, the temperature of T1 can be any temperature within the standard black body temperature range;

[0083] Step S203, taking out the window material, keeping the standard black body temperature at T1, and using the Fourier spectroradiometer to directly measure the spectral radiation value of the standard black body;

[0084] Step S204, setting the standard black body temperature to T2 and measuring the spectral radiation value transmitted through the temperature control device; optionally, the temperature of T2 can be any temperature within the standard black body temperature range that is different from the temperature of T1;

[0085] Step S205, taking out the window material, keeping the standard black body temperature at T2, and using the Fourier spectroradiometer to directly measure the spectral radiation value of the standard black body;

[0086] Step S206 , obtaining the spectral transmittance of the window material based on the spectral radiation values ​​of the standard black body and the temperature control device measured when the standard black body is at the temperature T1 and the temperature T2.

[0087] Specifically, when the standard black body is set to a temperature of T1, the radiation value M of the standard black body is directly measured using a Fourier spectroradiometer. T1 (λ) and the radiation value M of the standard black body measured through the window material by Fourier spectroradiometer C1 The relationship between (λ) is expressed as:

[0088] M C1 (λ)=M T1 (λ)×τ(λ)+M 1

[0089] Among them, M C1 (λ) is the spectral radiation value transmitted through the window material when the standard black body is set at temperature T1; M T1 (λ) is the spectral radiation value of the standard black body at the set temperature T1; τ(λ) is the spectral transmittance of the window material; M 1 is the stray radiation value.

[0090] Furthermore, when the standard black body is set to a temperature of T2, the radiation value M of the standard black body is directly measured using a Fourier spectrum radiometer. T2 (λ) and the radiation value M of the standard black body measured through the window material by Fourier spectroradiometer C2 The relationship between (λ) is expressed as:

[0091] M C2 (λ)=M T2 (λ)×τ(λ)+M 1

[0092] Among them, M C2 (λ) is the spectral radiation value transmitted through the window material when the standard black body is set at temperature T2; M T2 (λ) is the spectral radiation value of the standard black body when the temperature is set to T2.

[0093] Furthermore, the spectral transmittance of the window material is calculated using the processor based on the above two equations:

[0094]

[0095] Furthermore, when measuring the spectral radiation value transmitted through the temperature control device, the spectral radiation emitted by the standard black body passes through the first cold shield, the temperature control device, the second cold shield in sequence to the Fourier spectroradiometer.

[0096] Furthermore, when measuring the normal spectral emissivity of the window material, such as Figure 4 As shown, the following steps are included:

[0097] Step S301, pre-measuring the spectral transmittance of the window material;

[0098] Step S302, setting the temperature control device between the reflector and the Fourier spectroradiometer to measure the spectral radiation value of the window material;

[0099] Step S303, setting the standard black body temperature to be consistent with the temperature of the temperature control device;

[0100] Step S304, placing the standard black body in front of the Fourier spectroradiometer, and measuring the spectral radiation value of the standard black body;

[0101] Step S305 , obtaining the normal spectral emissivity of the window material based on the spectral transmittance of the window material, the spectral radiation value of the window material and the spectral radiation value of the standard black body.

[0102] Specifically, since the window material is a light-transmitting material, when measuring its emissivity, its surface emissivity will be emitted from the back side through the material itself, so it is necessary to simultaneously measure the emissivity of both the front and back surfaces and add them together to obtain the emissivity of the window material itself.

[0103] The back radiation of the window material is reflected by the reflector to the window material and then transmitted to the Fourier spectroradiometer together with the front radiation of the window material.

[0104] Therefore, the radiation measurement value of the window material is expressed by the following formula:

[0105] M C (λ)=M B (λ)×ε B (λ)×ε(λ)+M B (λ)×ε B (λ)×ρ(λ)×ε(λ)×τ(λ)

[0106] Among them, M C (λ) is the spectral radiation value of the window material; M B (λ) is the spectral radiation value of the standard black body; ε B(λ) is the normal spectral emissivity of the standard black body; ε(λ) is the normal spectral emissivity of the window material; ρ(λ) is the reflectivity of the reflector; τ(λ) is the spectral transmittance of the window material.

[0107] Further, the normal spectral emissivity of the window material is calculated by the processor using the following formula, derived from the above formula:

[0108]

[0109] Furthermore, a first cold shield and a second cold shield are placed in front of two radiation ports of the temperature control device respectively; the spectral radiation of the window material is emitted to the reflector and the Fourier spectroradiometer respectively through the first cold shield and the second cold shield.

[0110] In summary, a method for measuring radiation characteristics of a material according to an embodiment of the present invention has the following features:

[0111] Beneficial effects:

[0112] 1. The test method of the present invention can accurately measure the radiation characteristics of materials under high temperature conditions, wherein the measurement band range is 3μm~5μm, 8μm~14μm, the measurement angle range is ±10°, the temperature range is 300K~800K, and the measurement uncertainty is ≤6% (emissivity uncertainty: 4% for opaque materials, 6% for transparent materials; transmittance uncertainty: 4%).

[0113] 2. The measuring method used in the present invention can measure three radiation characteristics of two materials by adjusting the positions of the measured material, the standard black body and the Fourier spectroradiometer, which is easy to operate and highly practical.

[0114] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for measuring radiation characteristics of a material, comprising the following steps: The material to be tested is placed in a temperature control device, with the center of the material to be tested facing the radiation port of the temperature control device, and is set to a set temperature; the material to be tested is a structural material or a window material; Adjusting the positions of the material to be tested, the standard black body and the Fourier spectrum radiometer so that the radiation signals emitted by the material to be tested and the standard black body can be respectively received by the Fourier spectrum radiometer and measured to obtain the spectral radiation value; Based on the spectral radiation values ​​emitted by the material under test and the standard black body, the radiation characteristics of the material are calculated using a processor; include: The normal spectral emissivity of the structural material, the radiation transmittance of the window material, and the normal spectral emissivity of the window material calculated based on the radiation transmittance.

2. The method according to claim 1, It is characterized in that When measuring the normal spectral emissivity of structural materials, this includes: Placing the standard black body opposite to one radiation port of the temperature control device, and closing the other radiation port; Setting the standard blackbody temperature to be consistent with the temperature of the temperature control device; Swinging the folding and swinging mirror between the standard black body and the temperature control device to switch the radiation signals emitted by the structural material and the standard black body and transmit them to the Fourier spectroradiometer, and alternately measuring the spectral radiation value of the structural material and the spectral radiation value of the standard black body; The normal spectral emissivity of the structural material is obtained based on the spectral radiation value of the structural material and the spectral radiation value of the standard black body.

3. The method according to claim 2, It is characterized in that Based on the spectral radiation value of the structural material and the spectral radiation value of the standard black body, the normal spectral emissivity of the structural material is calculated using the following formula: Where ε(λ) is the normal spectral emissivity of the structural material; M sample (λ) is the spectral radiation value of the structural material; M B (λ) is the spectral radiation value of the standard black body; ε B (λ) is the normal spectral emissivity of the standard black body.

4. The method according to claim 3, It is characterized in that The spectral radiation of the structural material is emitted to the folding and swinging mirror through the cold shield.

5. The method according to claim 1, It is characterized in that When measuring the spectral transmittance of window materials, include: The temperature control device is arranged between the standard black body and the Fourier spectroradiometer; Setting the standard black body temperature to T1 and measuring the spectral radiation value transmitted through the temperature control device; Taking out the window material, keeping the standard black body temperature at T1, and using the Fourier spectroradiometer to directly measure the spectral radiation value of the standard black body; Setting the standard black body temperature to T2 and measuring the spectral radiation value transmitted through the temperature control device; Taking out the window material, keeping the standard black body temperature at T2, and using the Fourier spectroradiometer to directly measure the spectral radiation value of the standard black body; The spectral transmittance of the window material is obtained based on the spectral radiation values ​​of the standard black body and the temperature control device measured when the standard black body temperature is T1 and when the temperature is T2.

6. The method according to claim 5, It is characterized in that Based on the spectral radiation values ​​of the standard black body and the temperature control device measured when the standard black body temperature is T1 and the temperature is T2, the spectral transmittance of the window material is calculated using the following formula: Where τ(λ) is the spectral transmittance of the window material; M C1 (λ) is the spectral radiation value transmitted through the window material when the standard black body is set at temperature T1; M C2 (λ) is the spectral radiation value transmitted through the window material when the standard black body is set at temperature T2; M T1 (λ) is the spectral radiation measurement value of the standard black body at temperature T1; M T2 (λ) is the spectral radiation measurement value of the standard black body at temperature T2.

7. The method according to claim 6, It is characterized in that When measuring the spectral radiation value transmitted through the temperature control device, the spectral radiation emitted by the standard black body passes through the first cold shield, the temperature control device, the second cold shield in sequence to the Fourier spectroradiometer.

8. The method according to claim 1, It is characterized in that When measuring the normal spectral emissivity of a window material, include: Pre-measuring the spectral transmittance of the window material; The temperature control device is arranged between the reflector and the Fourier spectroradiometer to measure the spectral radiation value of the window material; Setting the standard blackbody temperature to be consistent with the temperature of the temperature control device; Placing the standard black body in front of the Fourier spectroradiometer to measure the spectral radiation value of the standard black body; Based on the spectral transmittance of the window material, the spectral radiation value of the window material and the spectral radiation value of the standard black body, the normal spectral emissivity of the window material is obtained.

9. The method according to claim 8, It is characterized in that Based on the spectral radiation value of the window material and the spectral radiation value of the standard black body, the normal spectral emissivity of the window material is calculated using the following formula: Where ε(λ) is the normal spectral emissivity of the window material; M c (λ) is the spectral radiation value of the window material; M B (λ) is the spectral radiation value of the standard black body; ε B (λ) is the normal spectral emissivity of the standard black body; ρ(λ) is the reflectivity of the reflector; τ(λ) is the spectral transmittance of the window material.

10. The method according to claim 9, It is characterized in that The spectral radiation of the window material is emitted to the reflecting mirror and the Fourier spectroradiometer respectively through the first cold shield and the second cold shield.

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