Detection distance scaling test method for airborne infrared photoelectric product

Abstract

The invention discloses an airborne infrared photoelectric product detection distance scaling test method, and belongs to the technical field of infrared photoelectric product detection distance test verification. The method comprises the following steps: establishing a relational expression between a detection distance of an airborne infrared photoelectric product to a simulated target and a detection distance of the airborne infrared photoelectric product to a typical target according to a detection principle of the airborne infrared photoelectric product; an airborne infrared photoelectric product detection distance scaling test environment is constructed in a ground infield; completing radiation calibration of the thermal imager; calibrating the atmospheric transmission path transmittance under the detection distance in real time; carrying out the detection distance scaling test of the airborne infrared photoelectric product; according to the scaling test result, the detection distance of the airborne infrared photoelectric product is calculated, and detection distance performance evaluation of the airborne infrared photoelectric product on the typical target is completed. According to the invention, the real atmospheric environment transmission path is introduced to complete the detection distance scaling test of the airborne infrared photoelectric product in the internal field, so that the external field test flight cost can be effectively reduced, and the test credibility and comprehensiveness are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of infrared photoelectric product detection distance test and verification, and in particular relates to a detection distance reduction test method for airborne infrared photoelectric products. Background Art

[0002] Infrared detection distance is a core indicator of airborne infrared optoelectronic products such as infrared search and tracking systems. The key factor affecting infrared search and tracking systems is how to accurately test the infrared detection distance conveniently. Traditional verification methods use field test flights or indoor sensitivity test methods. Field test flights have a long verification cycle and high costs, so the cost is huge and the difficulty is also great. At the same time, with the improvement of the detection distance performance of airborne infrared optoelectronic products, the difficulty of selecting test flight target aircraft and coordinating test flight airspace has become increasingly prominent. The indoor sensitivity test only assesses the response sensitivity of airborne optoelectronic products in a laboratory environment, and cannot effectively introduce the impact of the transmission path in the real atmospheric environment on the detection distance.

[0003] Therefore, those skilled in the art have proposed a scaled detection method for infrared detection distance. For example, an in-field test method for the detection distance of an imaging infrared system has been disclosed. This method uses the illumination equivalence principle. The test device is easy to build and operate. It is suitable for simulating the detection distance of a weak point target in a space background in a laboratory. However, this method does not take into account the atmospheric transmittance in the actual transmission path. Therefore, the actual probe distance cannot be obtained in the in-field test, and the detection sensitivity is low. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides a method for testing the detection distance scale-down of airborne infrared optoelectronic products. By combining the real target radiation intensity and the atmospheric transmittance on the real transmission path under the typical aircraft-target situation scenario, the real atmospheric environment transmission path is introduced to complete the detection distance scale-down test of airborne infrared optoelectronic products in the indoor field, which can effectively reduce the cost of outdoor flight tests and improve the credibility and comprehensiveness of the test, and quickly complete the agile test and evaluation of the detection distance performance of airborne optoelectronic products, and has good engineering practicality.

[0006] The technical solution of the present invention is: a method for testing the detection distance reduction ratio of airborne infrared optoelectronic products, and the specific steps are as follows:

[0007] According to the detection principle of airborne infrared optoelectronic products, the long-range detection performance of airborne infrared optoelectronic products is converted into an equivalent test under the ground short-range real atmospheric transmission path, and the relationship between the detection distance of airborne infrared optoelectronic products for simulated targets and the detection distance of airborne infrared optoelectronic products for typical targets is established;

[0008] Construct a detection range reduction test environment for airborne infrared optoelectronic products in the ground field;

[0009] Complete the thermal imager radiation calibration;

[0010] Real-time calibration of atmospheric transmission path transmittance at the detection distance;

[0011] Conduct detection distance reduction test of airborne infrared optoelectronic products;

[0012] According to the scaled test results, the detection distance of the airborne infrared optoelectronic product is calculated, and the detection distance performance evaluation of the airborne infrared optoelectronic product for typical targets is completed.

[0013] A further technical solution of the present invention is: the relationship between the distance from the airborne infrared optoelectronic product to the simulated target and the distance from the airborne infrared optoelectronic product to the typical target is:

[0014]

[0015] Among them, R 1 Indicates the detection distance of the airborne infrared optoelectronic product to the simulated target, R 2 Indicates the detection distance of airborne infrared optoelectronic products to typical targets, τ 1 Indicates the atmospheric transmittance on the transmission path when testing the simulated target detection distance, τ 2 It represents the atmospheric transmittance on the actual transmission path when testing the typical target detection distance, J 1 Represents the simulated target radiation intensity detected by airborne infrared optoelectronic products, J 2 Indicates the actual target radiation intensity detected by airborne infrared optoelectronic products.

[0016] A further technical solution of the present invention is: the detection distance reduction test environment of the airborne infrared optoelectronic product includes a surface source black body and a thermal imager. The surface source black body is used as a standard radiation source to simulate the target, and is also used for radiation calibration of the thermal imager and real-time calibration of the transmittance of the atmospheric transmission path at the reduction test detection distance.

[0017] A further technical solution of the present invention is: the specific operation of the thermal imager radiation calibration is:

[0018] With the help of the surface source blackbody, the close-range extended source method is used to complete the radiation calibration of the thermal imager. The radiation calibration model is:

[0019] DN=α·L+DN o

[0020] Where DN is the grayscale value output by the thermal imager, α is the radiant brightness response of the thermal imager to be calibrated, L is the radiant brightness of the surface source blackbody in the response band of the thermal imager, and DN is 0It is the response offset value caused by the thermal radiation of the thermal imager itself and the dark current of the detector;

[0021] Place the thermal imager optical axis perpendicular to the surface source black body, with the distance between the two no greater than 20 cm, and ensure that the surface source black body completely covers the thermal imager optical aperture;

[0022] In principle, the calibration temperature range of the thermal imager includes the target temperature to be measured. Determine the integration time parameters for normal imaging of the thermal imager and the upper and lower limits of the surface source blackbody temperature during calibration. Start from the lower limit of the surface source blackbody temperature setting and gradually increase to the upper limit of the temperature in a certain step. After the temperature of the surface source blackbody is stable at each temperature point, the thermal imager collects and records the image.

[0023] The least square method is used to perform linear fitting on multiple sets of calibration data collected to complete the radiation calibration of the thermal imager.

[0024] A further technical solution of the present invention is: the calculation formula of the radiation brightness L of the surface source black body in the response band of the thermal imager is as follows:

[0025]

[0026] In the formula, λ 1 ~λ 2 is the response band of the thermal imager, ε is the surface source blackbody emissivity, T is the surface source blackbody temperature, C 1 =(3.7415±0.0003)×10 8 (W·m -2 μm 4 ), C 2 =(1.4388±0.0002)×10 84 (μm·K).

[0027] A further technical solution of the present invention is that the number of the temperature points is not less than 10.

[0028] A further technical solution of the present invention is: the method for real-time calibration of the transmittance of the atmospheric transmission path under the detection distance is:

[0029] Place a surface source black body next to a simulated target in the detection range reduction test environment of the airborne infrared optoelectronic product at a distance of no more than 1 meter, place a radiation-calibrated thermal imager next to the airborne infrared optoelectronic product at a distance of no more than 1 meter, and adjust the optical axis of the thermal imager to be perpendicular to the surface source black body;

[0030] The temperature of the surface source blackbody is set at a certain temperature value within the calibration temperature range of the thermal imager. The radiation brightness L of the surface source blackbody at this temperature is B Calculated by Planck's law;

[0031] The surface source blackbody imaging data is collected by the thermal imager, and the radiation brightness L′ of the surface source blackbody reaching the thermal imager is obtained according to the radiation calibration data. B ;

[0032] The transmittance of computer-mounted infrared optoelectronic products under the real atmospheric transmission path in the detection distance reduction test environment:

[0033] A further technical solution of the present invention is: the specific operation of the airborne infrared optoelectronic product detection distance reduction test is:

[0034] A surface source black body is used as a simulated target and placed in the detection distance reduction test environment of the airborne infrared optoelectronic product. The distance between the simulated target and the airborne infrared optoelectronic product is R 1 , adjust the optical axis of the airborne infrared optoelectronic product to be perpendicular to the surface source blackbody;

[0035] Set the surface source blackbody temperature to ensure that the airborne infrared optoelectronic product can stably detect the target at a detection probability not lower than the detection probability requirement after it is powered on and working normally. Gradually reduce the surface source blackbody temperature in steps of 0.1°C until the airborne infrared optoelectronic product stably detects the target with a probability lower than the detection probability requirement. Record the last surface source blackbody setting temperature value, and calculate the radiation brightness L of the simulated target surface source blackbody in the scaled test environment according to Planck's law. 1 As a typical Lambertian radiation source, the surface source black body has a radiation area A. b Get the radiation intensity J 1 =L 1 ·A b .

[0036] A further technical solution of the present invention is: the detection distance calculation formula of the airborne infrared optoelectronic product is:

[0037]

[0038] A further technical solution of the present invention is: the atmospheric transmittance τ on the actual transmission path when testing the typical target detection distance 2 and the actual target radiation intensity detected by airborne infrared optoelectronic products J 1 Calculated by atmospheric radiation transfer software.

[0039] Beneficial Effects

[0040] The beneficial effects of the present invention are as follows: the present invention proposes a method for scaling down the detection distance of airborne infrared optoelectronic products. The method combines the real target radiation intensity and the atmospheric transmittance on the real transmission path under the typical aircraft-target situation scenario, and converts the actual detection distance requirement into the close-range target detection distance under the real atmospheric environment transmission path. The method can quickly complete the agile test of the detection distance limit and boundary performance of airborne optoelectronic products under different atmospheric environment transmission paths under typical aircraft-target situations, which can effectively reduce the cost of field test flights and improve the credibility and comprehensiveness of the test, and has good engineering practicality.

[0041] Compared with the traditional indoor sensitivity test, the detection distance assessment accuracy of optoelectronic products using this method has been reduced from no less than 15% to less than 10% relative to the actual detection distance obtained from outdoor test flights, effectively improving the credibility of the detection distance assessment of optoelectronic products. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the radiation calibration layout of the thermal imager.

[0043] Figure 2 This is a schematic diagram of the layout of the reduced-scale test environment for the detection distance of airborne infrared optoelectronic products.

[0044] Explanation of the reference numerals: 1. Surface source black body, 2. Thermal imager, 3. Simulated target placement platform, 4. Airborne infrared photoelectric detection equipment, 5. Product placement platform. DETAILED DESCRIPTION

[0045] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0046] Based on the existing disclosed infrared detection distance reduction detection method, the atmospheric transmittance in the real transmission path is not considered, resulting in the inability to obtain the real detection distance in the indoor field test, and the detection sensitivity is low. The present invention provides an airborne infrared optoelectronic product detection distance reduction test method, and the specific steps are as follows:

[0047] Step 1: The detection principle of airborne infrared optoelectronic products can convert the long-range detection performance of airborne infrared optoelectronic products into an equivalent test under the ground short-range real atmospheric transmission path:

[0048] Step 1.1: According to the Hudson formula, the detection distance is affected by the target radiation characteristics, the atmospheric environment transmission path and the performance of the airborne infrared optoelectronic product itself:

[0049]

[0050] Where D 0 , τ 0are respectively the incident aperture diameter and transmittance of the optical system of the airborne infrared optoelectronic product, J is the target radiation intensity, τ a is the atmospheric transmission path transmittance from the detected target to the airborne infrared optoelectronic product under typical aircraft-to-aircraft situation, D * , A d , Δf are the specific detection rate, pixel area and equivalent noise bandwidth of the airborne infrared optoelectronic product sensor, V s / V n is the signal-to-noise ratio of airborne infrared optoelectronic products;

[0051] Step 1.2: Further decomposing the Hudson formula yields:

[0052]

[0053] In the formula, Related to the optical system of airborne infrared optoelectronic products, J 1 / 2 Related to the target radiation characteristics, τ a 1 / 2 Related to the transmittance of the atmospheric transmission path, Related to the performance of airborne infrared optoelectronic product sensors, Related to the signal processing capabilities of airborne infrared optoelectronic products.

[0054] Step 1.3: Under the premise that the design indicators of airborne infrared optoelectronic products are determined, the product optical system, sensor performance and signal processing capabilities are all fixed values. The detection distance capability of airborne infrared optoelectronic products for different targets is only related to the target radiation intensity and the atmospheric transmittance on the path. It can be obtained:

[0055]

[0056] In the formula, R 1 , R 2 Different detection distances of airborne infrared optoelectronic products, τ 1 , τ 2 is the atmospheric transmission path transmittance at different detection distances, J 1 , J 2 To detect the target radiation intensity at different distances.

[0057] Step 2: Construct a scaled-down test environment for the detection distance of airborne infrared optoelectronic products in the ground field. The surface source black body is used as a standard radiation source to simulate the target. It is also used for the radiation calibration of the thermal imager and the real-time calibration of the transmittance of the atmospheric transmission path at the scaled-down test detection distance.

[0058] Step 3: Complete the thermal imager radiometric calibration:

[0059] Step 3.1: Use the close-range extended source method with the help of a surface source blackbody to complete the radiation calibration of the thermal imager. The radiation calibration model is:

[0060] DN=α·L+DN 0

[0061] Among them, DN is the grayscale value output by the thermal imager, α is the radiant brightness response of the thermal imager to be calibrated, and L is the radiant brightness of the surface source black body in the response band of the thermal imager, which can be calculated by Planck's law. DN 0 is the response offset value caused by the thermal radiation of the thermal imager itself and the dark current of the detector,

[0062]

[0063] In the formula, λ 1 ~λ 2 is the response band of the thermal imager, ε is the surface source blackbody emissivity, T is the surface source blackbody temperature, C 1 =(3.7415±0.0003)×10 8 (W·m -2 μm 4 ), C 2 =(1.4388±0.0002)×10 84 (μm·K).

[0064] Step 3.2: To ensure calibration accuracy, the surface source blackbody needs to cover the optical aperture of the thermal imager, and the optical axis of the thermal imager is placed perpendicular to the surface source blackbody, and the distance between the two should not exceed 20 cm;

[0065] Step 3.3: Based on the principle that the calibration temperature range of the thermal imager includes the target temperature to be measured, determine the integration time parameters for normal imaging of the thermal imager and the upper and lower limits of the surface source blackbody temperature that need to be set during calibration. Start from the lower limit of the surface source blackbody temperature setting and gradually increase to the upper limit of the temperature in a certain step length. After the temperature of the surface source blackbody is stable at each temperature point, the thermal imager collects and records the image. The number of collected temperature points is recommended to be no less than 10.

[0066] Step 3.4: Use the least squares method to perform linear fitting on the multiple sets of calibration data collected to complete the radiation calibration of the thermal imager.

[0067] Step 4: Real-time calibration of atmospheric transmission path transmittance at detection distance:

[0068] Step 4.1: Place the surface source blackbody next to the simulated target in the detection range reduction test environment of the constructed airborne infrared optoelectronic product. The recommended distance is no more than 1 meter. Place the radiation-calibrated thermal imager next to the airborne infrared optoelectronic product. The recommended distance is no more than 1 meter. Adjust the thermal imager optical axis to be perpendicular to the surface source blackbody.

[0069] Step 4.2: Set the surface source blackbody temperature to a certain temperature value within the thermal imager calibration temperature range. The radiation brightness L of the surface source blackbody at this temperature isB It can be calculated by Planck's law;

[0070] Step 4.3: The thermal imager collects the imaging data of the surface source blackbody. According to the radiation calibration data, the radiation brightness L′ of the surface source blackbody reaching the thermal imager can be obtained. B ;

[0071] Step 4.4: Calculate the transmittance of the airborne infrared optoelectronic product under the real atmospheric transmission path in the detection distance scaled test environment.

[0072]

[0073] Step 5: Airborne infrared optoelectronic product detection distance reduction test:

[0074] Step 5.1: Place the surface source black body as a simulated target in the constructed airborne infrared optoelectronic product detection distance reduction test environment. The distance between the simulated target and the airborne infrared optoelectronic product is R. 1 , taking the surface source black body as the simulation target, adjust the optical axis of the airborne infrared optoelectronic product to be perpendicular to the surface source black body;

[0075] Step 5.2: Set the surface source blackbody temperature to ensure that the airborne infrared optoelectronic product can stably detect the target at a detection probability not lower than the detection probability requirement after it is powered on and working normally. Gradually reduce the surface source blackbody temperature in steps of 0.1°C until the airborne infrared optoelectronic product stably detects the target at a probability lower than the detection probability requirement. Record the last surface source blackbody setting temperature value, and calculate the radiation brightness L of the simulated target surface source blackbody under the scaled test environment according to Planck's law. 1 As a typical Lambertian radiation source, the surface source black body can be divided into two types according to its radiation area A. b Get the radiation intensity J 1 =L 1 ·A b .

[0076] Step 6: Based on the scaled test results, the detection distance of the airborne infrared optoelectronic product can be calculated, and the detection distance performance evaluation of the airborne infrared optoelectronic product for typical targets can be completed.

[0077]

[0078] In the formula, J 2 is the actual target radiation intensity detected by airborne infrared optoelectronic products, τ 2 It is the atmospheric transmittance on the actual transmission path under a typical aircraft-target situation scenario, which can be calculated using general atmospheric radiation transmission software such as MODTRAN.

[0079] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for testing the detection distance of airborne infrared optoelectronic products, characterized in that The specific steps are as follows: According to the detection principle of airborne infrared optoelectronic products, the long-range detection performance of airborne infrared optoelectronic products is converted into an equivalent test under the ground short-range real atmospheric transmission path, and the relationship between the detection distance of airborne infrared optoelectronic products for simulated targets and the detection distance of airborne infrared optoelectronic products for typical targets is established; Construct a detection range reduction test environment for airborne infrared optoelectronic products in the ground field; Complete the thermal imager radiation calibration; Real-time calibration of atmospheric transmission path transmittance at the detection distance; Conduct detection distance reduction test of airborne infrared optoelectronic products; According to the scaled test results, the detection distance of the airborne infrared optoelectronic product is calculated, and the detection distance performance evaluation of the airborne infrared optoelectronic product for typical targets is completed.

2. According to claim 1, a method for testing the detection distance of an airborne infrared optoelectronic product is characterized in that: The relationship between the distance between the airborne infrared optoelectronic product and the simulated target and the distance between the airborne infrared optoelectronic product and the typical target is: Among them, R1 represents the detection distance of the airborne infrared optoelectronic product to the simulated target, R2 represents the detection distance of the airborne infrared optoelectronic product to the typical target, τ1 represents the atmospheric transmittance on the transmission path when testing the simulated target detection distance, τ2 represents the atmospheric transmittance on the actual transmission path when testing the typical target detection distance, J1 represents the radiation intensity of the simulated target detected by the airborne infrared optoelectronic product, and J2 represents the radiation intensity of the actual target detected by the airborne infrared optoelectronic product.

3. According to claim 2, a method for testing the detection distance of an airborne infrared optoelectronic product is characterized in that: The airborne infrared optoelectronic product detection distance scaled test environment includes a surface source black body and a thermal imager. The surface source black body is used as a standard radiation source to simulate a target, and is also used for radiation calibration of the thermal imager and real-time calibration of the transmittance of the atmospheric transmission path at the scaled test detection distance.

4. According to claim 3, a method for testing the detection distance of an airborne infrared optoelectronic product is characterized in that: The specific operation of the thermal imager radiation calibration is: With the help of the surface source blackbody, the close-range extended source method is used to complete the radiation calibration of the thermal imager. The radiation calibration model is: DN=α·L+DN0 Where, DN is the grayscale value output by the thermal imager, α is the radiant brightness response of the thermal imager to be calibrated, L is the radiant brightness of the surface source black body in the response band of the thermal imager, and DN0 is the response offset value caused by the thermal radiation of the thermal imager itself and the dark current of the detector; Place the thermal imager optical axis perpendicular to the surface source black body, with the distance between the two no greater than 20 cm, and ensure that the surface source black body completely covers the thermal imager optical aperture; In principle, the calibration temperature range of the thermal imager includes the target temperature to be measured. Determine the integration time parameters for normal imaging of the thermal imager and the upper and lower limits of the surface source blackbody temperature during calibration. Start from the lower limit of the surface source blackbody temperature setting and gradually increase to the upper limit of the temperature in a certain step. After the temperature of the surface source blackbody is stable at each temperature point, the thermal imager collects and records the image. The least square method is used to perform linear fitting on multiple sets of calibration data collected to complete the radiation calibration of the thermal imager.

5. According to claim 4, a method for testing the detection distance of an airborne infrared optoelectronic product is characterized in that: The calculation formula of the radiation brightness L of the surface source black body in the thermal imager response band is as follows: Where λ1~λ2 is the response band of the thermal imager, ε is the surface source blackbody emissivity, T is the surface source blackbody temperature, C1=(3.7415±0.0003)×10 8 (W·m -2 μm 4 ), C2=(1.4388±0.0002)×10 84 (μm·K).

6. According to claim 5, a method for testing the detection distance of an airborne infrared optoelectronic product is characterized in that: The number of the temperature points is not less than 10.

7. The method for testing the detection distance of an airborne infrared optoelectronic product according to claim 6, characterized in that: The method for real-time calibration of the atmospheric transmission path transmittance at the detection distance is: Place a surface source black body next to a simulated target in the detection range reduction test environment of the airborne infrared optoelectronic product at a distance of no more than 1 meter, place a radiation-calibrated thermal imager next to the airborne infrared optoelectronic product at a distance of no more than 1 meter, and adjust the optical axis of the thermal imager to be perpendicular to the surface source black body; The temperature of the surface source blackbody is set at a certain temperature value within the calibration temperature range of the thermal imager. The radiation brightness L of the surface source blackbody at this temperature is B Calculated by Planck's law; The surface source blackbody imaging data is collected by the thermal imager, and the radiation brightness L of the surface source blackbody reaching the thermal imager is obtained according to the radiation calibration data. ′ B ; The transmittance of computer-mounted infrared optoelectronic products under the real atmospheric transmission path in the detection distance reduction test environment:

8. The method for testing the detection distance of an airborne infrared optoelectronic product according to claim 7, characterized in that: The specific operation of the airborne infrared optoelectronic product detection distance reduction test is as follows: A surface source black body is used as a simulated target and placed in the detection distance reduction test environment of the airborne infrared optoelectronic product. The distance between the simulated target and the airborne infrared optoelectronic product is R1, and the optical axis of the airborne infrared optoelectronic product is adjusted to be perpendicular to the surface source black body; Set the surface source blackbody temperature to ensure that the airborne infrared optoelectronic product can stably detect the target at a detection probability not lower than the detection probability requirement after it is powered on and working normally. Gradually reduce the surface source blackbody temperature in steps of 0.1°C until the airborne infrared optoelectronic product stably detects the target at a probability lower than the detection probability requirement. Record the last surface source blackbody setting temperature value, and calculate the radiation brightness L1 of the simulated target surface source blackbody under the scaled test environment according to Planck's law. The surface source blackbody is a typical Lambertian radiation source according to its radiation area A. b The radiation intensity J1 = L1·A b .

9. The method for testing the detection distance of an airborne infrared optoelectronic product according to claim 8, characterized in that: The detection distance calculation formula of the airborne infrared optoelectronic product is:

10. The method for testing the detection distance of an airborne infrared optoelectronic product according to claim 9, characterized in that: The atmospheric transmittance τ2 on the actual transmission path during the test of the typical target detection distance and the actual target radiation intensity J1 detected by the airborne infrared optoelectronic product are calculated by the atmospheric radiation transmission software.

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