A method for testing the field of view angle of an infrared radiometer based on a surface source black body

Abstract

This invention discloses a method for testing the field of view of an infrared radiometer based on a blackbody. The steps are as follows: S1, Set up the blackbody and infrared radiometer, power on the infrared radiometer, and wait until it reaches thermal equilibrium; S2, Power on the blackbody, and after the blackbody temperature stabilizes, fine-tune the position of the blackbody; S3, Set the blackbody temperature to ambient temperature -5°C, and observe the reading of the infrared radiometer after the temperature stabilizes; Set the blackbody temperature to ambient temperature +10°C, observe the change in the infrared radiometer reading during the heating process of the blackbody, and record the blackbody temperature corresponding to the minimum reading; S4, Set the blackbody temperature and fine-tune it, and record the blackbody temperature of the blackbody when the infrared radiometer reading is the lowest; S5, Set the blackbody temperature, and after the temperature stabilizes, record the corresponding reading of the infrared radiometer; S6, Calculate the field of view of the infrared radiometer. This invention can effectively test the field of view of an infrared radiometer with high measurement accuracy and high precision.

Description

Technical Field

[0001] This invention belongs to the field of infrared radiation measurement technology, and in particular relates to a method for measuring the field of view of an infrared radiometer based on a surface source blackbody. Background Technology

[0002] In recent years, infrared technology has been widely used in both military and civilian engineering fields. An infrared radiometer is an optical instrument that measures infrared irradiance and target radiation intensity. It has advantages such as small size, light weight, low power consumption, high reliability, and low cost, and is widely used in aerospace, defense, scientific research, and industrial and agricultural production.

[0003] When using an infrared radiometer for testing, it is usually necessary to reasonably determine the test distance based on parameters such as the size of the infrared radiometer's field of view, the size of the target, and the detection response range of the infrared radiometer, and adjust the proportion of the target and background in the infrared radiometer's field of view to improve the effectiveness of the test.

[0004] Generally, the field of view can be calculated based on the design parameters of the infrared radiometer's optical system. However, due to limitations in the assembly process, the relative positions of the various optical components will deviate from the design values, resulting in an error between the calculated field of view and the actual field of view. While a high-precision turntable and a point-source blackbody can be used to measure the field of view of an infrared radiometer, this method requires high precision from the turntable and strict control of the blackbody temperature. Furthermore, the measurement results are easily affected by errors in the infrared radiometer's aiming axis, making it impractical for field testing. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a method for measuring the field of view of an infrared radiometer based on a surface-source blackbody.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for measuring the field of view of an infrared radiometer based on a blackbody source includes the following steps: S1. First, set up the blackbody and infrared radiometer: place the blackbody in front of the infrared radiometer, aim the infrared radiometer at the center of the radiation surface of the blackbody, and make the aiming axis of the infrared radiometer perpendicular to the radiation surface of the blackbody. The distance between the blackbody and the entrance pupil of the infrared radiometer is L. Then, power on the infrared radiometer until it reaches thermal equilibrium. S2. Power on the blackbody and set the temperature to 10°C above the ambient temperature. After the blackbody temperature stabilizes, finely adjust the position of the blackbody back and forth. If the reading of the infrared radiometer does not change, it means that the radiation surface of the blackbody covers the entire field of view of the infrared radiometer. If the reading of the infrared radiometer changes significantly, shorten the distance L between the blackbody and the infrared radiometer and test again until the reading of the infrared radiometer does not change when the position of the blackbody is moved back and forth. S3. Set the surface source blackbody temperature to be 5°C lower than the ambient temperature. After the temperature stabilizes, observe the reading of the infrared radiometer. Set the surface source blackbody temperature to be 10°C higher than the ambient temperature. Observe the change in the infrared radiometer reading during the heating process of the surface source blackbody, and record the blackbody temperature T corresponding to the minimum reading. temp ; S4. Set the surface source blackbody temperature to T temp And make fine adjustments up and down, and record the surface source blackbody temperature T0 when the infrared radiometer reading is the lowest, which is the internal radiation equivalent blackbody temperature of the current infrared radiometer. S5. Set the surface source blackbody temperature to After the temperature stabilizes, record the corresponding readings of the infrared radiometer. The reading of the infrared radiometer Represented as equation (6): (6) In the formula, The emissivity of the surface-source blackbody is represented by k; k represents the calibration coefficient. The surface source blackbody temperature is T. i The radiative exitance in the infrared band is calculated using Planck's formula. This represents the equivalent radiative exitance of the infrared radiometer's internal radiation in the specified band, calculated using Planck's formula. Indicates the field of view angle of the infrared radiometer; S6. Use formula (7) to calculate the field of view of the infrared radiometer. : (7).

[0007] Furthermore, in step S1 above, the distance L between the blackbody and the entrance pupil of the infrared radiometer is determined based on the size of the blackbody's radiation surface to ensure that the blackbody's radiation surface can cover the entire field of view of the infrared radiometer.

[0008] Furthermore, in steps S2 and S3 above, the ambient temperature is 10–30°C.

[0009] Due to the adoption of the technical solution described above, the present invention has the following advantages: This method for testing the field of view of an infrared radiometer based on a blackbody surface source effectively measures the field of view of the radiometer by measuring the equivalent blackbody temperature inside the radiometer. It is easy to operate, simple to process data, has high measurement accuracy, high precision, and is highly practical with a wide range of applications. It can be used to correct errors in field of view calculation caused by assembly errors in the optical system components, and can also guide the field testing of the infrared radiometer's field of view, demonstrating significant potential for widespread application. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the infrared radiometer field of view measurement method based on a surface source blackbody according to the present invention. Detailed Implementation

[0011] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0012] like Figure 1 As shown, a method for measuring the field of view of an infrared radiometer based on a blackbody source includes the following steps: S1. First, set up the blackbody and infrared radiometer: Place the blackbody in front of the infrared radiometer, aim the infrared radiometer at the center of the blackbody’s radiation surface, and make the aiming axis of the infrared radiometer perpendicular to the blackbody’s radiation surface. The distance between the blackbody and the entrance pupil of the infrared radiometer is L. This distance L is determined based on the size of the blackbody’s radiation surface to ensure that the blackbody’s radiation surface can cover the entire field of view of the infrared radiometer. (a) Assuming the temperature of the surface source blackbody is T1, and the field of view of the infrared radiometer is... With a calibration coefficient of k, ignoring the influence of internal radiation of the infrared radiometer, the irradiance E(T1) reaching the entrance pupil of the infrared radiometer is calculated according to equation (1): (1) In the formula, This represents the radiative exitance in the infrared band when the surface source blackbody temperature is T1, calculated using Planck's formula. Indicates the emissivity of the surface-source blackbody; Indicates the field of view angle of the infrared radiometer; At this point, the reading U(T1) of the infrared radiometer is obtained according to equation (2): (2) However, since the infrared radiometer uses a modulation disk to modulate the incident radiation signal in the main optical path, the thermal radiation of the modulation disk will have a significant impact on the response of the infrared radiometer, causing the infrared radiometer to produce an indication output even when there is no input signal. (b) Define the equivalent blackbody temperature of the radiation inside the infrared radiometer as T0. Adjust the surface source blackbody temperature and observe the change in the output value of the infrared radiometer. When the output value of the infrared radiometer is 0 or close to 0, the temperature of the blackbody is T0. T0 is about 2~3℃ higher than the body temperature of the infrared radiometer.

[0013] Considering the influence of internal radiation of the infrared radiometer, the irradiance E(T1) reaching the entrance pupil of the infrared radiometer when the temperature of the surface source blackbody is T1 is calculated according to equation (3): (3) In the formula, This represents the equivalent radiative exitance of the infrared radiometer's internal radiation in the specified band, calculated using Planck's formula. Considering the influence of internal radiation of the infrared radiometer, the reading U(T1) of the infrared radiometer is expressed as equation (4): (4) The field of view of the infrared radiometer is obtained according to equation (4). The expression: (5); Then, power on the infrared radiometer for 30 to 50 minutes until it reaches internal thermal equilibrium. S2. Power on the blackbody and set the temperature to 10°C above the ambient temperature. Fine-tune the position of the blackbody back and forth. If the reading of the infrared radiometer does not change, it means that the radiation surface of the blackbody covers the entire field of view of the infrared radiometer. If the reading of the infrared radiometer changes significantly, shorten the distance between the blackbody and the infrared radiometer and test again until the reading of the infrared radiometer does not change when the position of the blackbody is moved back and forth at a certain distance. Preferably, the ambient temperature is 10-30°C. S3. Set the surface source blackbody temperature to be 5°C lower than the ambient temperature. After the temperature stabilizes, observe the reading of the infrared radiometer. Set the surface source blackbody temperature to be 10°C higher than the ambient temperature. Observe the change in the infrared radiometer reading during the heating process of the surface source blackbody, and record the blackbody temperature T corresponding to the minimum reading. temp Preferably, the ambient temperature is 10–30°C. S4. Set the surface source blackbody temperature to T temp And make fine adjustments up and down, and record the surface source blackbody temperature T0 when the infrared radiometer reading is the lowest, which is the internal radiation equivalent blackbody temperature of the current infrared radiometer. S5. Set the surface source blackbody temperature to , The temperature should ideally be 50°C higher than the ambient temperature; after the temperature stabilizes, record the corresponding readings of the infrared radiometer. The reading of the infrared radiometer Represented as equation (6): (6) In the formula, The emissivity of the surface-source blackbody is represented by k; k represents the calibration coefficient. The surface source blackbody temperature is T. i The radiative exitance in the infrared band is calculated using Planck's formula. This represents the equivalent radiative exitance of the infrared radiometer's internal radiation in the specified band, calculated using Planck's formula. Indicates the field of view angle of the infrared radiometer; S6. Use formula (7) to calculate the field of view of the infrared radiometer. : (7).

[0014] The present invention provides a field-of-view measurement method for infrared radiometers based on a blackbody source, which requires the following preparatory measures: (1) Before conducting the test, the response rate of the infrared radiometer should be calibrated; (2) Use a blackbody with good emissivity stability. Before testing, calibrate the main parameters of the blackbody, such as emissivity and temperature control accuracy. (3) During the test, the internal radiation equivalent blackbody temperature of the infrared radiometer will change slowly. Taking the average value of multiple tests can reduce the test error of the internal radiation equivalent blackbody temperature of the infrared radiometer. (4) The surface source blackbody temperature should be as large as possible compared to the internal radiation equivalent blackbody temperature of the infrared radiometer. The greater the difference between the blackbody temperature and the internal radiation equivalent blackbody temperature of the infrared radiometer, the smaller the impact of the blackbody temperature control error on the test results.

[0015] In addition, during testing, because the infrared radiometer is close to the blackbody and the blackbody has a high temperature, the time for the blackbody to heat up and stabilize is relatively long. In order to ensure the internal thermal balance of the infrared radiometer, it is necessary to properly insulate the infrared radiometer during the measurement process to effectively reduce the thermal radiation received by the infrared radiometer during the blackbody temperature stabilization process.

[0016] The following test examples verify the field-of-view angle testing method of the infrared radiometer based on a surface source blackbody according to the present invention.

[0017] The black bodies used in the test were the JQ-100MYD1B low-temperature black body and the JQ-200MYZ3B medium-temperature black body manufactured by Wuhan Kelvin Optoelectronic Technology Co., Ltd., and their main technical parameters are shown in Table 1.

[0018] Table 1 Main Technical Parameters of Blackbody

[0019] During testing, the infrared radiometer was positioned 250 mm away from the blackbody radiation surface. A dual-channel thermometer was used to monitor the probe housing and ambient temperature. First, using a low-temperature blackbody source, the equivalent blackbody temperature T0 inside the infrared radiometer was measured to be 33.5℃ using steps S1-S3 described above. Then, the temperature of the medium-temperature blackbody source was set to 100℃, 120℃, 140℃, 160℃, 180℃, and 200℃ respectively. After the blackbody source stabilized at the set temperature, the corresponding readings of the infrared radiometer were recorded. The specific data obtained from the tests are shown in Table 2.

[0020] The calibration coefficient k of the infrared radiometer under test is 0.9655 after calibration, and the emissivity of the blackbody source is 0.95. According to equation (7), the field of view value obtained at each blackbody source temperature can be calculated. The specific results are shown in Table 2.

[0021] Table 2 Test Results

[0022] The average field of view of the six tests was 8.39°, which is close to the calculated field of view of 8.73°. The standard deviation of the field of view of the six tests was 0.013°. The test results showed strong consistency, which is consistent with the rule that the field of view of the infrared radiometer is a constant value.

[0023] The above description is only a preferred embodiment of the present invention and not a limitation thereof. Any equivalent changes and modifications made in accordance with the scope of the present invention without departing from the spirit and scope of the present invention shall be within the scope of patent protection of the present invention.

Claims

1. A method for testing the field of view angle of an infrared radiometer based on a surface source blackbody, characterized in that: It includes the following steps: S1. First, set up the blackbody and infrared radiometer: place the blackbody in front of the infrared radiometer, aim the infrared radiometer at the center of the radiation surface of the blackbody, and make the aiming axis of the infrared radiometer perpendicular to the radiation surface of the blackbody. The distance between the blackbody and the entrance pupil of the infrared radiometer is L. Then, power on the infrared radiometer until it reaches thermal equilibrium. S2. Power on the blackbody and set the temperature to 10°C above the ambient temperature. After the blackbody temperature stabilizes, finely adjust the position of the blackbody back and forth. If the reading of the infrared radiometer does not change, it means that the radiation surface of the black body covers the entire field of view of the infrared radiometer. If the reading of the infrared radiometer changes significantly, shorten the distance L between the black body and the infrared radiometer and test again until the reading of the infrared radiometer does not change when the position of the black body is moved back and forth. S3. Set the surface source blackbody temperature to 5°C lower than the ambient temperature. After the temperature stabilizes, observe the reading of the infrared radiometer. Set the surface source blackbody temperature to 10°C higher than the ambient temperature. Observe the change in the infrared radiometer reading during the heating process and record the blackbody temperature T corresponding to the minimum reading. temp ; S4. Set the surface source blackbody temperature to T temp And make fine adjustments up and down, and record the surface source blackbody temperature T0 when the infrared radiometer reading is the lowest, which is the internal radiation equivalent blackbody temperature of the current infrared radiometer. S5, set the surface source blackbody temperature to After the temperature is stable, record the corresponding indication of the infrared radiation meter The indication of the infrared radiation meter is expressed as formula (6): （6） In the formula, The emissivity of the surface-source blackbody is represented by k; k represents the calibration coefficient. The surface source blackbody temperature is T. i The radiative exitance in the infrared band is calculated using Planck's formula. This represents the equivalent radiative exitance of the infrared radiometer's internal radiation in the specified band, calculated using Planck's formula. Indicates the field of view of the infrared radiometer; S6, calculate the field of view angle of the infrared radiometer using equation (7) : （7）。 2. The method of claim 1, wherein the method further comprises: In step S1, the distance L between the blackbody and the entrance pupil of the infrared radiometer is determined based on the size of the blackbody's radiation surface to ensure that the blackbody's radiation surface can cover the entire field of view of the infrared radiometer.

3. The method of claim 1, wherein the method further comprises: In steps S2 and S3, the ambient temperature is 10–30°C.

Images