A satellite-ground combined radiation calibration method and device for a large-aperture infrared camera

Abstract

The application provides a star-ground combined radiation calibration method and device for a large-aperture infrared camera, and relates to the field of space-based infrared quantitative measurement. The method calculates the on-orbit absolute radiation calibration coefficient of a single pixel through star calibration data, and combines the ground relative radiation calibration coefficient obtained by the post-optical path blackbody calibration to extend the on-orbit absolute radiation calibration coefficient of the single pixel to the on-orbit absolute radiation calibration coefficient of the whole image plane, solves the problem that the single-pixel calibration coefficient cannot be applied to the whole image plane inversion, realizes the absolute radiation calibration of the whole image plane, and corrects the ground calibration coefficient. The method fuses the ground and on-orbit calibration results, provides the large-aperture infrared camera with high-precision and high-reliability radiation calibration capability, and meets the high-precision quantitative measurement requirement.

Description

Technical Field

[0001] This invention relates to the field of space-based infrared quantitative measurement, and more specifically, to a method and apparatus for joint satellite-ground radiometric calibration of large-aperture infrared cameras. Background Technology

[0002] The quantification of remote sensing information is an important direction and inevitable trend for the future development of remote sensing science and technology. The radiative transfer calibration of the massive remote sensing image data acquired by each infrared detection channel of the space payload is a prerequisite for its quantification. Its main purpose is to establish an accurate radiative transfer model for each infrared detection channel of the space payload.

[0003] Through radiometric calibration experiments, a radiative transfer model for each infrared detection channel of the space payload can be established, that is, the functional relationship between the input (radiance value at the entrance pupil) and the output (image grayscale value) of each infrared detection channel can be determined; then, appropriate imaging parameters such as gain, integration time and frame rate can be set for each infrared detection channel under various operating conditions to improve the detection capability of the target.

[0004] Currently, in-orbit absolute radiometric calibration typically uses blackbody as the reference source. However, as optical payloads develop towards larger apertures and observe smaller targets, single blackbody calibration is no longer sufficient to meet calibration requirements. Therefore, stars have been developed as another in-orbit reference source. Stars offer better stability and traceability, and can calibrate the lower-end radiation profiles. However, this is only single-pixel absolute radiometric calibration, and current technology cannot yet convert single-pixel calibration coefficients to full-image calibration coefficients. Summary of the Invention

[0005] To address the need for high-precision quantitative measurements using existing large-aperture infrared cameras, this invention provides a satellite-ground joint radiometric calibration method and apparatus for large-aperture infrared cameras. This method calculates the absolute radiometric calibration coefficients of a single pixel using stellar calibration data and combines them with the non-uniform calibration coefficients obtained from the subsequent optical path blackbody calibration to extend the single-pixel calibration coefficients to the entire image plane. This solves the problem that single-pixel calibration coefficients cannot be applied to full-image plane inversion, achieving absolute radiometric calibration of the entire pixel and correcting the ground calibration coefficients.

[0006] The above-mentioned technical objective of this invention is achieved through the following technical solution: a satellite-to-ground joint radiometric calibration method for large-aperture infrared cameras, comprising:

[0007] Step 1: Calculate the absolute radiometric calibration coefficients of the entire image plane using a blackbody with the entire optical path, and obtain the relative radiometric calibration coefficients using a blackbody with the rear optical path. The absolute radiometric calibration coefficients of the entire image plane and the relative radiometric calibration coefficients constitute the ground calibration coefficients.

[0008] Step 2: Calculate the on-orbit absolute radiometric calibration coefficient of a single pixel using stellar calibration data, and combine it with the relative radiometric calibration coefficient to extend the on-orbit absolute radiometric calibration coefficient of the single pixel to the on-orbit absolute radiometric calibration coefficient of the entire image plane.

[0009] Step 3: Correct the ground calibration coefficients using the on-orbit absolute radiometric calibration coefficients of the holographic plane.

[0010] The present invention also provides a satellite-to-ground joint radiometric calibration device for large-aperture infrared cameras, comprising:

[0011] The ground calibration coefficient calculation module calculates the absolute radiometric calibration coefficient of the ground in the whole image plane through the all-optical-path blackbody, and obtains the relative radiometric calibration coefficient through the rear-optical-path blackbody calibration. The absolute radiometric calibration coefficient of the ground in the whole image plane and the relative radiometric calibration coefficient constitute the ground calibration coefficient.

[0012] The whole-image-plane on-orbit absolute radiometric calibration coefficient calculation module calculates the on-orbit absolute radiometric calibration coefficient of a single pixel using stellar calibration data, and combines it with the relative radiometric calibration coefficient to extend the on-orbit absolute radiometric calibration coefficient of a single pixel to the whole-image-plane on-orbit absolute radiometric calibration coefficient.

[0013] The ground calibration coefficient correction module uses the on-orbit absolute radiometric calibration coefficient of the full-image plane to correct the ground calibration coefficient.

[0014] The present invention also provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the method described above.

[0015] The present invention also provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, cause the processor to implement the above-described method.

[0016] In summary, the present invention has the following beneficial effects:

[0017] This invention provides a satellite-ground joint radiometric calibration method and apparatus for large-aperture infrared cameras. By combining ground-based radiometric calibration with on-orbit absolute radiometric calibration using multiple star sources, and utilizing an on-board blackbody in the rear optical path for non-uniformity correction, it solves the problem that single-pixel calibration coefficients cannot be applied to the entire image plane, achieving full-image-plane absolute radiometric calibration and significantly improving calibration accuracy and system stability. Simultaneously, multi-frame accumulation technology is employed to suppress background noise, improve the reliability of stellar luminosity measurements, and dynamically correct the impact of instrument state changes on calibration coefficients, enhancing the system's adaptability and consistency. This method integrates ground and on-orbit calibration results, providing high-precision and high-reliability radiometric calibration capabilities for large-aperture infrared cameras, meeting the requirements for high-precision quantitative measurements. By utilizing the technical solution of this invention, single-pixel absolute calibration coefficients can be calculated with relatively few on-board resources and then converted to full-image-plane calibration coefficients with high precision, achieving a calibration accuracy better than 5%. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating an implementation of a satellite-ground joint radiometric calibration method for a large-aperture infrared camera in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the ground blackbody calibration equipment layout in an embodiment of the present invention;

[0020] Figure 3 This is a flowchart of ground blackbody calibration in an embodiment of the present invention. Detailed Implementation

[0021] 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. To achieve the above objectives, this invention adopts the following technical solution.

[0022] Example 1:

[0023] A satellite-to-ground joint radiometric calibration method for large-aperture infrared cameras, such as... Figure 1 As shown, it includes the following steps:

[0024] Step 1: Calculate the absolute radiometric calibration coefficients of the entire image plane using a blackbody with the entire optical path, and obtain the relative radiometric calibration coefficients using a blackbody with the rear optical path. The absolute radiometric calibration coefficients of the entire image plane and the relative radiometric calibration coefficients constitute the ground calibration coefficients.

[0025] A surface-source calibration method was employed to conduct infrared radiation calibration experiments on each infrared detection channel of the space payload in a vacuum chamber in a ground-based laboratory. Specifically, a surface-source calibration blackbody with an effective radiating surface size sufficient to cover the space payload's field of view was placed in the vacuum chamber as the full-path blackbody. By changing the blackbody temperature, the radiation energy at the space payload's entrance pupil was altered. Simultaneously, the grayscale data of the corresponding output images from the cameras were collected, allowing the calculation of the absolute radiation calibration coefficient for each pixel and yielding the calibration curve. The calibration blackbody temperature was recorded. The spectral radiance at that time was Then, according to Planck's law, we can obtain:

[0026] ,

[0027] ,

[0028] In the formula, Let be the surface emissivity of the blackbody. and These are the first and second radiation constants, respectively; The average spectral radiance of the blackbody. and To detect the start and end wavelengths of the channel, Let be the spectral response function of the camera. Let be the response of a certain detection channel of the camera to temperature . When a blackbody is imaged, a certain pixel The output image grayscale value is When imaging a cold background (cold space in orbit or a cold screen inside a ground vacuum tank), this pixel... The output image grayscale value is Then we have:

[0029] ,

[0030] ,

[0031] In the formula, The average spectral radiance at the camera entrance pupil during blackbody imaging. For a certain detection channel pixel of the camera The response rate is a parameter that needs to be determined in absolute radiation calibration tests. The average spectral radiance of the total stray radiation reaching the camera entrance pupil (excluding the blackbody) when imaging a blackbody. The average spectral radiance of the camera's instrument background at the moment of blackbody imaging; The average spectral radiance at the camera entrance pupil when imaging a cold screen / cold space is the total stray radiation reaching the camera entrance pupil. To measure the average spectral radiance of the camera's instrument background at the moment of imaging the cold screen / cold space, This is for DC bias in the circuit.

[0032] Subtracting the two equations above, we get:

[0033] ,

[0034] In absolute radiation calibration experiments, multiple sets of results can be obtained by changing the blackbody temperature. and The value of the pixel in a certain detection channel of the camera can be calculated by using fitting algorithms such as the least squares method to perform linear function or polynomial fitting and correction on these calibration data sets. Ground absolute radiation calibration coefficient Furthermore, the ground absolute radiometric calibration coefficients of the entire image plane are obtained. It can also evaluate the calibration error of the corrected calibration data.

[0035] After capturing 100 frames of images using the blackbody on the back-light path star, the mean is estimated. The relative radiometric calibration coefficients of the entire image plane are calculated by subtracting the cold screen / cold space image response from these images. (Full-image plane relative radiometric calibration coefficients) The calculation formula is as follows:

[0036] ,

[0037] In the formula, This is the response output value of the entire image plane (after subtracting the cold background response). This is the average image plane response (after deducting the cold background response).

[0038] The specific layout of the ground blackbody calibration equipment is as follows: Figure 2 As shown, the device consists of several key components, with the overall structure located inside a vacuum chamber to simulate the space environment. The core of the device is a turntable, on which a camera and a blackbody are mounted, separated by a baffle to avoid stray light interference. A collimator is connected to the left side of the device to generate uniform parallel light to illuminate the camera. Outside the vacuum chamber, a camera ground inspection chassis and a blackbody controller are connected, respectively, via cables to the camera and blackbody. The camera ground inspection chassis is connected to a camera ground inspection computer for camera data processing and analysis; the blackbody controller adjusts the temperature and radiation parameters of the blackbody through the blackbody control computer, thereby achieving precise control of the blackbody. These components work together to complete the optical inspection and calibration tasks of the device. The calibration process is as follows: Figure 3As shown, firstly, the calibration point is precisely located using a servo positioning system, the camera's imaging parameters are collected, and the device is adjusted to the calibration position. During this process, background radiation data is collected to assess the impact of the environmental background and for subsequent data correction and analysis. Subsequently, the position of the calibration point is adjusted, and the calibration position operation is repeated to expand the coverage area or improve measurement accuracy. Next, reference data on the camera's optical axis direction is collected to ensure accurate alignment, and blackbody radiation characteristic data is collected to verify its stability. Once the data is confirmed to be valid, the experimental setup is gradually brought back to normal operating conditions, and a comprehensive status check is performed to verify that the equipment maintains normal operating status after the experiment. Finally, the calibration data is processed and analyzed. This series of steps ensures high accuracy and repeatability of the calibration work.

[0039] Step 2: Calculate the on-orbit absolute radiometric calibration coefficient of a single pixel using stellar calibration data, and combine it with the relative radiometric calibration coefficient to extend the on-orbit absolute radiometric calibration coefficient of the single pixel to the on-orbit absolute radiometric calibration coefficient of the entire image plane.

[0040] First, based on the camera's observation requirements and the observed sky area, several suitable stellar sources are selected as stellar calibration reference sources. Multiple frames of stellar images are stacked, and stellar luminosity is estimated from the stacked images. The stellar luminosity estimation results are then used... Absolute radiometric calibration is performed to obtain the absolute radiometric calibration of a single pixel. The calculation formula is shown below:

[0041] ,

[0042] ,

[0043] In the formula, Let (i, j) be the response value of pixel (i, j). , Using the centroid coordinates, the coordinates are derived from the outer pixels of the stellar region (R). Mean estimate of R) As background radiation This is the final stellar response value. The calibration formula is:

[0044] ,

[0045] In the formula, Here, B is the absolute radiometric calibration coefficient for a single pixel, and B is the intercept. This refers to stellar irradiance; multiple sets of data are obtained by sampling multiple stars. The on-orbit absolute radiometric calibration coefficients of a single pixel were fitted using the least squares method. .

[0046] Relative radiometric calibration is performed using a blackbody on the satellite's back path. The relative radiometric calibration coefficients across the entire image plane are obtained by utilizing the homogeneity of the blackbody on the satellite; this method is consistent with the relative radiometric calibration using a blackbody on the ground.

[0047] Combining the total image plane and the relative radiometric calibration coefficients of a single pixel , The on-orbit absolute radiometric calibration coefficient of a single pixel Extended to full-image on-orbit absolute radiometric calibration coefficients Specifically:

[0048] ,

[0049] In the formula, The relative radiation calibration coefficient. for medium pixel The relative radiation calibration coefficient, For a single pixel The on-orbit absolute radiometric calibration factor.

[0050] Step 3: Estimate the correction coefficients using the on-orbit absolute radiometric calibration and ground calibration coefficients of the full-image plane:

[0051] .

[0052] More specifically, the present invention provides a specific embodiment.

[0053] Step 1 specifically includes:

[0054] Step 1.1: Calculate the spectral radiance at the calibrated blackbody temperature T using Planck's law. :

[0055] ,

[0056] ,

[0057] In the formula, Let be the surface emissivity of the blackbody. and These are the first and second radiation constants, respectively; The average spectral radiance of the blackbody. and To detect the start and end wavelengths of the channel, This is the spectral response function of the camera. Calibration testing will begin after the blackbody temperature stabilizes.

[0058] Step 1.2: Temperature point setting. This involves analyzing the radiation characteristics of the target to be detected and determining the target's radiation intensity. Detection range Pixel angular resolution Energy concentration Given the initial calculation conditions, the equivalent blackbody brightness can be calculated using the following formula. :

[0059] ,

[0060] Based on the blackbody surface emissivity Given the initial calculation conditions, the equivalent blackbody brightness can be calculated using Planck's formula. The equivalent temperature of the corresponding all-optical-path blackbody :

[0061] ,

[0062] By combining the above two equations with Planck's formula, the radiation intensity of several specific targets can be calculated. The equivalent temperature of the corresponding full-aperture calibrated blackbody .

[0063] The equivalent temperature of these all-optical-path blackbodies Set some additional temperature points at medium intervals (or according to overall requirements), generally no less than 11; the specified value of the blackbody temperature variation range is recommended to be determined according to the range of 10% to 90% of the output response signal saturation signal variation; if the test blackbody temperature variation cannot meet the response signal variation range of 10% to 90% of the output response signal voltage, the integration time can be adjusted.

[0064] Step 1.3: For each temperature point, acquire 500 frames of image data from the blackbody, estimate the mean value as the response image for that temperature point, and then analyze a specific pixel. The output image grayscale value is When imaging a cold background (cold space in orbit or a cold screen inside a ground vacuum tank), this pixel... The output image grayscale value is Then we have:

[0065] ,

[0066] ,

[0067] In the formula, For a certain detection channel pixel of the camera The response rate is a parameter that needs to be determined in absolute radiation calibration tests. The average spectral radiance of the total stray radiation reaching the camera entrance pupil (excluding the blackbody) when imaging a blackbody. The average spectral radiance of the camera's instrument background at the moment of blackbody imaging; The average spectral radiance at the camera entrance pupil when imaging a cold screen / cold space is the total stray radiation reaching the camera entrance pupil. To measure the average spectral radiance of the camera's instrument background at the moment of imaging the cold screen / cold space, This is for DC bias in the circuit.

[0068] Subtracting the two equations above, we get:

[0069] ,

[0070] In absolute radiation calibration experiments, multiple sets of results can be obtained by changing the blackbody temperature. and The value of the pixel in a certain detection channel of the camera can be calculated by using fitting algorithms such as the least squares method to perform linear function or polynomial fitting and correction on these calibration data sets. Ground absolute radiation calibration coefficient Furthermore, the ground absolute radiometric calibration coefficients of the full image plane containing all pixels are obtained. It can also evaluate the calibration error of the corrected calibration data.

[0071] After capturing 100 frames of images using the blackbody on the back-light path star, the mean is estimated. The relative radiometric calibration coefficients are then calculated by subtracting the cold screen / cold space image response from these images. (Relative radiometric calibration coefficients) The calculation formula is as follows:

[0072] ,

[0073] In the formula, This is the response output value of the entire image plane (after subtracting the cold background response). This is the average image plane response (after deducting the cold background response).

[0074] It should be noted that the above blackbody images should include ground-calibrated full-optical-path blackbody images and on-board (rear-optical-path) blackbody images, and the relationship between the two sets of blackbody radiation energy should be established based on these images. At the same time, for the same temperature point, under the same imaging parameter conditions, multiple sets of on-board blackbody images need to be acquired to measure and evaluate the repeatability of the on-board blackbody.

[0075] Step 1.4, Error Analysis, Absolute Radiation Calibration Accuracy Uncertainty of temperature measurement by blackbody Surface emissivity measurement uncertainty Relative radiation calibration error (Including image acquisition noise) and fitting error The decision is:

[0076] ,

[0077] The uncertainty in blackbody temperature measurement (better than 0.1K) and the uncertainty in surface emissivity measurement (better than 0.5%) were both obtained by qualified metrology units. The non-uniform correction error (related to the test temperature point) and the fitting error (generally better than 2%) were calculated from the radiation calibration test data and estimated during the design phase based on radiation calibration data from other similar models. The calculation method for the uncertainty in blackbody temperature measurement is as follows:

[0078] ,

[0079] In the formula, The temperature measurement accuracy of the resistance thermometer used for calibrating the blackbody. This is a temperature assessment point.

[0080] After capturing 100 frames of images using a blackbody on the back-light path star, the mean is estimated. The relative radiometric calibration coefficients are then calculated by subtracting the deep-space image response from these images. The total image plane relative radiometric calibration coefficients are then calculated. The calculation formula is as follows:

[0081] ,

[0082] In the formula, This is the response output value of the entire image plane (after subtracting the cold background response). This is the average image plane response (after deducting the cold background response).

[0083] Relative radiometric calibration error: Generally, a blackbody is used as the standard radiation source for non-uniformity correction. Therefore, the relative radiometric calibration accuracy is only related to factors such as image acquisition noise and the anisotropy of the blackbody surface emissivity. Based on the signal-to-noise ratio (SNR) design value, the noise of a single image acquisition can be calculated. Based on the current research and testing experience of calibrated blackbodies, the uncertainty of the anisotropy of the blackbodi surface emissivity is estimated to be approximately 0.5%, therefore:

[0084] ,

[0085] Step 2 specifically includes:

[0086] Step 2.1: Select multiple star sources as calibration stars for observation based on the requirements of the exploration mission and the camera observation area.

[0087] Step 2.2 Use the jitter mode to collect 100 frames of data for each calibration satellite.

[0088] Step 2.3 Preprocesses the obtained image. First, background estimation is performed. The main method is to replace the star response region in 100 frames of data with the mean of the nearby images, and then align and superimpose the estimated mean of the replaced images as the background image.

[0089] Step 2.4 performs bicubic interpolation on the processed stellar image, using an interpolation factor of 11 as an example, assuming one pixel is 11. Eleven sub-pixels constitute a super-resolution stellar image.

[0090] Step 2.5 involves stacking the collected super-resolution stellar images, which contain multiple sub-pixels. During stacking, the super-resolution stellar images need to be aligned, placing the stellar barycenters within the same pixel. The stacked images reduce energy loss due to undersampling and suppress the effects of background noise.

[0091] Step 2.6 Perform stellar photometric estimation on the stacked images (aperture photometry scheme), and use the stellar photometric estimation results ( Absolute radiometric calibration is performed. The aperture is selected based on the size of the star being imaged, using r... Taking r as an example, then it is necessary to calculate the pixels on the outer edge of the star region (R). The mean value of R) is used as the background radiation. :

[0092] ,

[0093] In the formula , Using the centroid coordinates, The response value of pixel (i, j), the final star response value for:

[0094] ,

[0095] Step 2.7 The formula for calibrating the absolute radiation of an on-orbit stellar source is:

[0096] ,

[0097] In the formula, Here, B is the absolute radiometric calibration coefficient for a single pixel, and B is the intercept. This refers to stellar irradiance; multiple sets of data are obtained by sampling multiple stars. The on-orbit absolute radiometric calibration coefficients of a single pixel were fitted using the least squares method. .

[0098] Combined with relative radiation calibration coefficients , The on-orbit absolute radiometric calibration coefficient of a single pixel Extended to full-image on-orbit absolute radiometric calibration coefficients Specifically:

[0099] ,

[0100] In the formula, The relative radiation calibration coefficient. for medium pixel The relative radiation calibration coefficient, For a single pixel The on-orbit absolute radiometric calibration factor.

[0101] Step 3 specifically includes:

[0102] The absolute calibration coefficients of the on-orbit panorama are obtained using steps 1 and 2. Absolute radiometric calibration coefficients of the whole-image ground Estimated correction coefficient :

[0103] .

Claims

1. A satellite-to-ground joint radiometric calibration method for large-aperture infrared cameras, characterized in that, Includes the following steps: Step 1: Calculate the absolute radiometric calibration coefficients of the entire image plane using a blackbody with the entire optical path, and obtain the relative radiometric calibration coefficients using a blackbody with the rear optical path. The absolute radiometric calibration coefficients of the entire image plane and the relative radiometric calibration coefficients constitute the ground calibration coefficients. Step 2: Calculate the on-orbit absolute radiometric calibration coefficient of a single pixel using stellar calibration data, and combine it with the relative radiometric calibration coefficient to extend the on-orbit absolute radiometric calibration coefficient of the single pixel to the on-orbit absolute radiometric calibration coefficient of the entire image plane. Step 3: Correct the ground calibration coefficients using the on-orbit absolute radiometric calibration coefficients of the full-image plane; in Step 2, the on-orbit absolute radiometric calibration coefficients of a single pixel are calculated using stellar calibration data as follows: First, based on the camera's observation requirements and the observed sky area, several suitable stellar sources were selected as stellar calibration reference sources. Multiple frames of stellar images were then stacked, and stellar luminosity was estimated from the stacked images. The stellar luminosity estimation results were then used... For absolute radiometric calibration, the aperture size is chosen to be r. r, the absolute radiometric calibration coefficient of a single pixel, is calculated using the following formula: ， ， In the formula, For pixels The response value, , Let R be the coordinates of the centroid, derived from the outermost pixel R of the stellar region. Mean estimate of R As background radiation This is the final stellar response value; the calibration formula is: ， In the formula, Here, B is the absolute radiometric calibration coefficient for a single pixel, and B is the intercept. This refers to stellar irradiance; multiple sets of data are obtained by sampling multiple stars. The on-orbit absolute radiometric calibration coefficients of a single pixel were fitted using the least squares method. ; Combining the total image plane and the relative radiometric calibration coefficients of a single pixel , The on-orbit absolute radiometric calibration coefficient of a single pixel Extended to full-image on-orbit absolute radiometric calibration coefficients Specifically: ， In the formula, The relative radiation calibration coefficient. for medium pixel The relative radiation calibration coefficient, For a single pixel The on-orbit absolute radiometric calibration factor.

2. The satellite-to-ground joint radiometric calibration method for a large-aperture infrared camera according to claim 1, characterized in that, In step 1, the calculation of the absolute radiometric calibration coefficient of the whole-image surface ground using a full-path blackbody is as follows: Record the temperature of the blackbody in the entire optical path The spectral radiance at that time was Then, according to Planck's law, we can obtain: ， ， In the formula, Let be the surface emissivity of the blackbody. and These are the first and second radiation constants, respectively; The average spectral radiance of the blackbody. and To detect the start and end wavelengths of the channel, Let be the spectral response function of the camera; Record the temperature of a certain detection channel of the camera. When imaging a blackbody using an all-optical-path method, a certain pixel The output image grayscale value is ; When imaging against a cold background, this pixel The output image grayscale value is Then we have: ， ， In the formula, The average spectral radiance at the camera entrance pupil during blackbody imaging. For a certain detection channel pixel of the camera The response rate is a parameter that needs to be determined in absolute radiation calibration tests. The average spectral radiance of the total stray radiation reaching the camera entrance pupil (excluding the blackbody) when imaging a blackbody. The average spectral radiance of the camera's instrument background at the moment of blackbody imaging; The average spectral radiance at the camera entrance pupil when imaging against a cold background is the total stray radiation reaching the camera entrance pupil. To measure the average spectral radiance of the camera's own instrument background at the moment of imaging against a cold background, DC bias for the circuit; Subtracting the two equations above, we get: ， By changing the temperature of the blackbody in the entire optical path, multiple sets of... and The value of the camera's detection channel is calculated by using fitting algorithms such as least squares to perform linear function or polynomial fitting and correction on these calibration data sets, thereby determining the pixel value of the camera's detection channel. Ground absolute radiation calibration coefficient Furthermore, the absolute radiometric calibration coefficients of the entire image plane were obtained. .

3. The satellite-to-ground joint radiometric calibration method for a large-aperture infrared camera according to claim 2, characterized in that, In step 1, the specific steps for obtaining the relative radiation calibration coefficients through the rear optical path blackbody calibration are as follows: Several frames of images were captured using the onboard blackbody in the rear optical path. The relative radiometric calibration coefficients were calculated by subtracting the background image response from these images, and the relative radiometric calibration coefficients of the entire image plane were obtained. The calculation formula is as follows: ， In the formula, This is the output response value of the full-image plane after subtracting the cold background response. This is the mean image plane response after deducting the cold background response.

4. The satellite-to-ground joint radiometric calibration method for a large-aperture infrared camera according to claim 1, characterized in that, The correction coefficients are estimated using the on-orbit absolute radiometric calibration and ground calibration coefficients of the full-image plane: 。 5. The satellite-to-ground joint radiometric calibration method for a large-aperture infrared camera according to claim 2, characterized in that, The equipment for calibrating a blackbody using an all-optical-path system includes a cold screen, turntable, camera, blackbody, collimator, blackbody temperature controller, camera ground inspection cabinet, camera ground inspection computer, and blackbody control calculator. The cold screen, turntable, camera, blackbody, and collimator are all located inside a vacuum chamber to simulate the space environment.

6. The satellite-to-ground joint radiometric calibration method for a large-aperture infrared camera according to claim 5, characterized in that, A camera and a blackbody are mounted on the turntable, separated by a baffle. A collimator is connected to the left side of the turntable to generate uniform parallel light to illuminate the camera. The camera ground inspection cabinet and the blackbody controller are connected to the outside of the vacuum tank, and are respectively connected to the camera and the blackbody via cables. The camera ground inspection chassis is connected to the camera ground inspection computer for camera data processing and analysis; the blackbody controller adjusts the temperature and radiation parameters of the blackbody through the blackbody control computer, thereby achieving precise control of the blackbody.

7. The satellite-to-ground joint radiometric calibration method for a large-aperture infrared camera according to claim 6, characterized in that, The specific method for calibrating a blackbody in an all-optical path is as follows: All-optical-path blackbody temperature control is used to determine camera imaging parameters; the camera optical axis is pointed to the cold screen to collect background radiation data. Adjust the blackbody temperature to the specified temperature point and stabilize it. Point the camera's optical axis towards the blackbody and acquire image data at that temperature point. Repeat the above steps to complete the acquisition of data for all temperature points.

8. A satellite-to-ground joint radiometric calibration device for large-aperture infrared cameras, which implements the method of claim 1, characterized in that, include: The ground calibration coefficient calculation module calculates the absolute radiometric calibration coefficient of the ground in the whole image plane through the all-optical-path blackbody, and obtains the relative radiometric calibration coefficient through the rear-optical-path blackbody calibration. The absolute radiometric calibration coefficient of the ground in the whole image plane and the relative radiometric calibration coefficient constitute the ground calibration coefficient. The whole-image-plane on-orbit absolute radiometric calibration coefficient calculation module calculates the on-orbit absolute radiometric calibration coefficient of a single pixel using stellar calibration data, and combines it with the relative radiometric calibration coefficient to extend the on-orbit absolute radiometric calibration coefficient of a single pixel to the whole-image-plane on-orbit absolute radiometric calibration coefficient. The ground calibration coefficient correction module uses the on-orbit absolute radiometric calibration coefficient of the full-image plane to correct the ground calibration coefficient.

9. An electronic device, characterized in that, include: One or more processors; A memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the method of any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores executable instructions that, when executed by a processor, cause the processor to perform the method described in any one of claims 1 to 7.

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