Material sample millimeter wave emissivity measuring system based on integrating sphere

Abstract

The invention provides a material sample millimeter wave emissivity measuring system based on an integrating sphere, which belongs to the technical field of passive microwave / millimeter wave remote sensing and detection and comprises the integrating sphere, a radiation source, a to-be-measured sample table and a radiometer antenna or a whole machine, the radiation source is arranged on the inner side of the sphere wall of the integrating sphere; the to-be-tested sample table is arranged in the integrating sphere; a flange is arranged on the outer side of the ball wall of the integrating sphere, the radiometer antenna or the whole machine is arranged on the ball shell of the integrating sphere through the flange and is aligned with the to-be-tested sample table, and the readings of the radiometer at different angles are obtained by adjusting the position of the radiometer antenna or the whole machine on the ball shell of the integrating sphere, so that the emissivity of the material sample at different angles is calculated. The device and the method can be suitable for measuring millimeter wave band emissivity of material samples with different surface forms and different temperatures, the emissivity value of the material sample can be obtained without measuring the material temperature and the environmental radiation brightness temperature, and the device and the method are high in measurement accuracy, convenient to operate and high in practicability.

Description

Technical Field

[0001] This invention belongs to the field of passive microwave / millimeter-wave remote sensing and detection technology, and more specifically, relates to a millimeter-wave emissivity measurement system for material samples based on an integrating sphere. Background Technology

[0002] In nature, all matter with a physical temperature above absolute zero spontaneously radiates electromagnetic energy in the form of electromagnetic waves, covering almost the entire wavelength range. Different substances have different radiation spectra. Millimeter-wave radiation detection technology has advantages such as all-weather and near-all-day operation, good penetration, and stealth, and has important applications in remote sensing, target detection, astronomy, and human security checks.

[0003] Millimeter-wave radiation detection technology uses millimeter-wave radiometers to receive millimeter-wave radiation from a target scene, enabling the measurement of the scene's radiation intensity. The magnitude of physical millimeter-wave radiation energy is determined by factors such as its millimeter-wave emissivity, physical temperature, and effective radiating area. Millimeter-wave emissivity is a key physical quantity characterizing a material's millimeter-wave radiation capability and an important parameter describing its millimeter-wave radiation characteristics. Accurate millimeter-wave emissivity measurements are not only used to verify radiation calculation models and evaluate material reflection and radiation characteristics, but also a prerequisite for target identification, clustering, and information extraction. Furthermore, they are crucial for establishing a database of millimeter-wave emissivity for common targets in potential application areas. Currently, with the development of millimeter-wave detection technology in target detection, there is an urgent need to measure the millimeter-wave emissivity of samples with different surface morphologies and at different temperatures.

[0004] Existing methods for measuring millimeter-wave emissivity in materials mainly include the brightness temperature method, the voltage method, and the differential irradiation method. The brightness temperature method, especially for small-sized material samples, is affected by antenna sidelobes and radiation from non-target regions. Furthermore, calibration accuracy also affects measurement accuracy. The voltage method requires a radiation reference at the same physical temperature for auxiliary measurement, limiting its application in measuring materials at very low temperatures, especially high temperatures. Both methods are difficult to use for direct measurement of rough surfaces. Currently, there is a strong demand for millimeter-wave emissivity measurement methods for rough surfaces across various millimeter-wave applications. The differential irradiation method can theoretically measure the emissivity of rough-surface materials; however, for rough-surface measurement, a semi-uniform irradiation environment is required, which current devices struggle to create. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a millimeter-wave emissivity measurement system for material samples based on an integrating sphere, thereby solving the technical problem of difficulty in measuring millimeter-wave emissivity of material samples that are rough or in very high-temperature conditions in existing technologies.

[0006] To achieve the above objectives, according to one aspect of the present invention, a millimeter-wave emissivity measurement system for material samples based on an integrating sphere is provided, comprising: an integrating sphere, a radiation source, a sample stage, and a radiometer antenna or the entire system;

[0007] The radiation source is located on the inner side of the wall of the integrating sphere; The sample stage to be tested is disposed inside the integrating sphere; A flange is provided on the outer side of the integrating sphere, and the radiometer antenna or the whole unit is mounted on the spherical shell of the integrating sphere through the flange and aligned with the sample stage to be tested; The radiation source is used to generate millimeter waves, which are continuously scattered and reflected within the integrating sphere to eventually form a stable, uniform, non-polarized irradiation environment. The position of the radiometer antenna or the entire unit on the integrating sphere shell is adjusted to change the angle between the radiometer antenna or the entire unit and the material sample on the test sample stage. The emissivity of the material sample at different angles is calculated by obtaining the radiometer readings at different angles.

[0008] More preferably, the radiometer antenna or the entire unit can be moved on the integrating sphere shell via a flange to adjust the detection angle of the material sample, the reflecting reference body, and the radiation reference body on the test sample stage.

[0009] Preferably, the direction of the electromagnetic wave emitted from the emission port of the radiation source makes an angle of 45° with the line connecting the radiation source and the center of the integrating sphere. After the radiation source interacts with the inner surface of the integrating sphere, a uniform irradiation environment can ultimately be achieved inside the sphere.

[0010] Preferably, it also includes an angle meter, which is disposed on the radiometer antenna or the whole unit, and is used to measure the detection angle of the radiometer antenna or the whole unit relative to the material sample, the reflective reference body and the radiation reference body in real time.

[0011] Preferably, the device further includes a material sample fixing device, which is disposed on the upper part of the sample stage to be tested. The material sample fixing device can fix material samples of various shapes and sizes onto the sample stage to facilitate subsequent measurement work.

[0012] Preferably, the sample stage is made of a wave-transparent material.

[0013] Preferably, the inner shell of the integrating sphere is a high-reflectivity surface with diffuse reflection characteristics, so as to ultimately make the interior of the integrating sphere approximately a uniform non-polarized irradiation environment.

[0014] Preferably, the radiation intensity of the radiation source is adjustable, thereby constructing uniform non-polarized irradiation environments of different intensities by adjusting the radiation intensity of the radiation source.

[0015] Preferably, the measurement system is also applicable to emissivity measurement in microwave, submillimeter wave, and terahertz bands. By designing integrating spheres of different sizes and replacing radiometers and radiation sources of different frequency bands, emissivity measurement of materials in different frequency bands can be achieved.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects: 1. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere proposed in this invention can construct a stable, uniform, non-polarized irradiation environment within the integrating sphere by using a radiation source placed inside the integrating sphere. By adjusting the position of the radiometer antenna or the entire unit on the integrating sphere shell, the angle between the radiometer antenna or the entire unit and the material sample on the test stage can be changed. By acquiring the radiometer readings at different angles, the emissivity of the material sample at different angles can be calculated. This system can measure the emissivity of samples under extremely low temperatures or with rough surfaces without needing to know the physical temperature of the material sample. It has high measurement accuracy and is easy to operate.

[0017] 2. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere proposed in this invention can quickly and accurately adjust the angle of the radiometer by using a flange and an angle meter to measure the millimeter-wave emissivity of the sample material at different angles. This method is more time-saving and labor-saving, and greatly improves the detection efficiency.

[0018] 3. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere proposed in this invention can fix material samples of various shapes and sizes in the material plate placement area by setting a material sample fixing device, so as to facilitate subsequent measurement work.

[0019] 4. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere proposed in this invention can achieve emissivity measurement of materials at different frequency bands by changing the size of the integrating sphere and replacing the radiometer and radiation source with different frequency bands.

[0020] 5. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere proposed in this invention is also applicable to emissivity measurement in the microwave, submillimeter-wave, and terahertz bands. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the millimeter-wave emissivity measurement system for material samples based on an integrating sphere, according to the present invention.

[0022] Figure 2 This is a schematic diagram of material sample radiation measurement in an embodiment of the material sample millimeter-wave emissivity measurement system based on an integrating sphere according to the present invention.

[0023] Wherein: 1-Integrating sphere; 2-Radiation source; 3-Sample stage to be tested; 4-Radiometer antenna or whole unit; 5-Material sample fixing device; 6-Flange; 7-Angle meter. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] like Figure 1 and Figure 2 As shown, this invention discloses a millimeter-wave emissivity measurement system for material samples based on an integrating sphere. It includes an integrating sphere 1, inside which a millimeter-wave radiation source 2 is fixedly installed; a sample stage 3, on which a material sample fixing device 5 is installed; a flange 6, fixedly installed on the shell of the integrating sphere 1; and a millimeter-wave radiometer antenna or the entire unit 4, which can be fixedly installed on the flange 6. An angle meter 7 is fixed on the millimeter-wave radiometer antenna or the entire unit 4.

[0026] Specifically, a millimeter-wave radiation source 2 is fixedly installed inside the integrating sphere 1.

[0027] In this embodiment, by adjusting the frequency bands of the millimeter-wave radiation source 2 and the millimeter-wave radiometer antenna or the whole machine 4, and the material sample fixing device 5, the integrating sphere 1 can meet the inspection needs of various specifications of samples in multiple frequency bands, making it highly practical.

[0028] Specifically, the direction of the electromagnetic wave emitted from the emission port of the radiation source 2 forms a 45° angle with the line connecting the radiation source and the center of the integrating sphere. After the radiation source 2 interacts with the inner surface of the integrating sphere 1, a uniform irradiation environment can ultimately be achieved inside the sphere.

[0029] In this implementation scheme, the inner shell of the opposing integrating sphere is stably fixed at the emission port of radiation source 2, so that the emission field of view of the radiation source remains stable.

[0030] Specifically, the radiometer antenna or the whole unit 4 is fixed on the flange 6, and the detection angles of the material sample, the reflective reference body, and the radiation reference body on the material plate placement area are adjusted.

[0031] Specifically, the sample stage 3 is equipped with a material sample fixing device 5.

[0032] In this embodiment, the material sample fixing device 5 can fix material samples of various shapes and sizes in the material plate placement area to facilitate subsequent measurement work.

[0033] Specifically, an angle meter 7 is fixed on the millimeter-wave radiometer antenna or the whole machine 4.

[0034] In this embodiment, an angle meter 7 is fixed on the millimeter-wave radiometer to measure the detection angle of the millimeter-wave radiometer relative to the material sample, the reflective reference body, and the radiation reference body on the material plate placement area.

[0035] Specifically, a millimeter-wave radiation source 2 is fixedly installed inside the integrating sphere 1.

[0036] In this embodiment, the inner shell of the integrating sphere is a highly reflective surface with certain diffuse reflection characteristics. A radiation source is fixedly installed inside the integrating sphere, and the radiation intensity of the radiation source is adjustable, so as to ultimately create a uniform non-polarized irradiation environment with different intensities inside the integrating sphere.

[0037] In use, the integrating sphere 1 is adjusted to a horizontal position, and the millimeter-wave radiation source 2 inside the integrating sphere is turned on. The millimeter waves generated by the radiation source inside the integrating sphere are continuously scattered and reflected on the diffuse reflection inner shell of the integrating sphere, ultimately forming a stable, uniform, non-polarized irradiation environment. By changing the intensity of the radiation source inside the integrating sphere, the irradiation intensity of the resulting uniform, non-polarized irradiation environment is altered. The test material sample, the reflecting reference, and the radiating reference are placed on the test sample stage 3 of the integrating sphere and fixed using the material sample fixing device 5. The main beam of the radiometer antenna or the entire unit 4 is completely projected onto the material sample, the reflecting reference, and the radiating reference, all three being in the same position with the same surface normal vector. The reading of the millimeter-wave radiometer is read. The position of the millimeter-wave radiometer antenna or the entire unit 4 on the integrating sphere shell is fixed using the flange 6 to adjust the detection angle of the material sample, the reflecting reference, and the radiating reference on the test sample stage 3, thus changing the angle between the radiometer antenna and the material sample. The readings of the millimeter-wave radiometer at different angles are obtained, and the emissivity of the material sample at different angles is obtained through subsequent mathematical calculations.

[0038] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A millimeter-wave emissivity measurement system for material samples based on an integrating sphere, characterized in that, include: Integrating sphere (1), radiation source (2), sample stage (3), and radiometer antenna or complete unit (4); The radiation source (2) is located on the inner side of the wall of the integrating sphere (1); The sample stage (3) to be tested is disposed inside the integrating sphere (1); A flange (6) is provided on the outer side of the wall of the integrating sphere (1). The radiometer antenna or the whole unit (4) is mounted on the shell of the integrating sphere (1) through the flange (6) and aligned with the sample stage (3) to be tested. The radiation source (2) is used to generate millimeter waves, which are continuously scattered and reflected within the integrating sphere (1) and eventually form a uniform non-polarized irradiation environment with stable intensity. The position of the radiometer antenna or the whole unit (4) on the spherical shell of the integrating sphere (1) is adjusted to change the angle between the radiometer antenna or the whole unit (4) and the material sample on the sample stage (3) to be tested. The emissivity of the material sample at different angles is calculated by obtaining the readings of the radiometer at different angles.

2. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere according to claim 1, characterized in that, The direction of the electromagnetic wave emitted from the emission port of the radiation source (2) is 45° with the line connecting the radiation source and the center of the integrating sphere.

3. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere according to claim 1, characterized in that, It also includes an angle meter (7), which is installed on the radiometer antenna or the whole machine (4) and is used to measure the angle detected by the radiometer antenna or the whole machine (4) in real time.

4. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere according to claim 1, characterized in that, It also includes a material sample fixing device (5), which is located on the upper part of the sample stage (3) to be tested.

5. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere according to claim 1, characterized in that, The test sample stage (3) is made of a wave-transparent material.

6. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere according to claim 1, characterized in that, The inner shell of the integrating sphere (1) is a highly reflective surface with diffuse reflection characteristics.

7. The millimeter-wave emissivity measurement system for material samples based on an integrating sphere according to claim 1, characterized in that, The radiation intensity of the radiation source (1) is adjustable, and a uniform non-polarized irradiation environment of different intensities can be constructed by adjusting the radiation intensity of the radiation source (1).

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