Nonlinear correction method for infrared hyperspectral remote sensing instrument radiated in non-ideal way

Abstract

The invention discloses a non-ideal path radiation infrared hyperspectral remote sensing instrument non-linear correction method, aiming at the situation that partial radiation of a stationary orbit GIIRS enters a detector in a non-ideal path in a complex thermal environment, and initial correction is carried out on an original spectrum of a detection target based on a responsivity non-linear correction algorithm during radiometric calibration; during in-orbit operation, a linear calibration model is constructed through a two-point calibration algorithm, and the spectral response rate of the detector and the theoretical radiation spectrum of an observation target are obtained; based on a nonlinear correction spectral response rate and a theoretical radiation spectrum of an observation target, in combination with non-ideal radiation superposed by an original spectrum of the detection target and a fixed error which cannot be corrected by two-point calibration, a function relationship between radiation abutting against a detector in a non-ideal way and the original spectrum of the detection target is constructed; the non-ideal path radiation correction coefficient is obtained, non-linear correction is further carried out, non-ideal radiation errors which cannot be corrected by response rate non-linear correction are eliminated, and the radiation calibration precision of the target black body is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of infrared detectors, and in particular relates to a nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation. Background Art

[0002] The interferometric infrared detector carried by Fengyun-4 satellite is the world's first Fourier transform infrared hyperspectral remote sensing instrument in geostationary orbit that detects three-dimensional atmospheric vertical structure by interferometric spectroscopy. Its remote sensing data is of great significance for improving numerical weather forecast models and improving the prediction accuracy of extreme weather events. In order to meet quantitative applications, accurate calibration results are a necessary condition, and nonlinear correction is a key step to improve the accuracy of radiation calibration. Nonlinearity is a comprehensive manifestation of complex systems. It is closely related to many factors such as the optoelectronic properties of detector materials, the design architecture of detection circuits, the design of optical systems and their components, the complex background temperature of the instrument, changes in the instrument's launch and on-orbit operation status, and component attenuation. It is used to describe the characteristics of the non-linear relationship between the detector output electrical signal and the system input optical power.

[0003] The nonlinearity introduced by the optical system is often limited by optimizing the system structure, such as optimizing optical shielding elements, controlling the surface quality and cleanliness of optical elements, setting specific optical compensation components, and designing flexible stray light suppression mechanisms according to needs. The nonlinearity caused by the photoelectric characteristics of the detector material and the design architecture of the detection circuit is removed by changing the design architecture of the detection circuit, such as an interferometer dual-output structure that eliminates nonlinear signals by combining two outputs of the same amplitude and opposite phase, or proposing a nonlinear correction circuit that weakens the influence of series resistance for the photoconductive detector circuit, or further weakening the nonlinearity of series resistance by adding positive feedback to the detection circuit, or changing the constant current bias of the HgCdTe detector to a constant voltage bias to suppress the circuit nonlinearity. This type of hardware correction method has poor adaptability because it only performs nonlinear correction for a specific structure.

[0004] For satellite-borne time-modulated Fourier transform hyperspectral infrared remote sensing instruments, the quadratic nonlinearity of the system is often considered for correction, and the detector receiving light intensity and the nonlinear response of the system are modeled for correction. For example, the autocorrelation function is used to detect and eliminate the nonlinear response of the detector, and the ideal linear system response is used as a constant to solve the correction coefficient to remove the nonlinearity on FY-3D HIRAS. Or based on the above method, several specific methods for obtaining the DC quantity of the interference pattern and the convergence of the nonlinear coefficient are refined.

[0005] Based on the nonlinear correction method of response rate, the present invention further considers the impact of target radiation entering the detector through a non-ideal path in view of the uneven distribution of sunlight on the orbit of the Fengyun-4 geostationary interferometric infrared sounder (FY-4 / GIIRS) and the drastic daily variation of the instrument ambient temperature, and performs nonlinear correction on the system. Summary of the invention

[0006] The purpose of the present invention is to provide a nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation paths. In view of the fact that part of the radiation of FY-4 / GIIRS in geostationary orbit enters the detector through non-ideal paths in a complex instrument thermal environment, a calculation model is established to solve the non-ideal incident path correction coefficient in the spectral dimension for nonlinear correction, thereby eliminating non-ideal radiation errors that cannot be corrected by nonlinear correction of partial response rate and improving the radiation calibration accuracy of the target blackbody.

[0007] To solve the above problems, the technical solution of the present invention is: A nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation, comprising: During radiation calibration, the nonlinear interference data of the detector is obtained, and based on the nonlinear correction algorithm of the response rate, the original spectrum of the detection target is preliminarily corrected to obtain the nonlinear correction spectrum response rate; During on-orbit operation, a linear calibration model is constructed through a two-point calibration algorithm. Based on the linear calibration model, the spectral response rate of the detector and the theoretical radiation spectrum of the observed target are obtained; Based on the nonlinear correction spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by two-point calibration, a functional relationship between the radiation reaching the detector through a non-ideal path and the original spectrum of the detection target is constructed to obtain a non-ideal path radiation correction coefficient; the radiation reaching the detector through a non-ideal path includes the radiation reaching the detector through a non-ideal path of the detection target and the radiation reaching the detector through a non-detection target.

[0008] According to an embodiment of the present invention, constructing a linear calibration model by using a two-point calibration algorithm further includes: For a linear system with constant radiation in the detector, the following linear calibration model is constructed: in, , , They are the original spectra generated by Fourier transform of the high-temperature calibration source, low-temperature calibration source, and the observed target interference pattern. , , are the theoretical radiation spectra of the high-temperature calibration source, low-temperature calibration source, and observation target, respectively. is the constant radiation inside the detector, and R is the spectral response rate of the linear system detector.

[0009] According to an embodiment of the present invention, based on the nonlinear correction spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detected target and the fixed error that cannot be corrected by the two-point calibration, constructing the functional relationship between the radiation reaching the detector through the non-ideal path and the original spectrum of the detected target further includes: Combining the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by two-point calibration, on the basis of non-linear correction based on response rate correction, the functional relationship between the radiation reaching the detector through the non-ideal path and the original spectrum of the detection target is constructed as follows: is the radiation value that reaches the detector through a non-ideal path. is the radiation correction factor for the non-ideal incident path, which represents the relationship between the original spectral integral and the non-ideal radiation; It is a fixed error of the detector under a certain working condition that cannot be corrected by two-point calibration; is the nonlinear corrected spectral response rate; E is the integral of the original spectrum of the detection target.

[0010] According to an embodiment of the present invention, based on the functional relationship between the radiation reaching the detector through a non-ideal path and the original spectrum of the detection target, combined with the calculation formula of the nonlinear correction spectral response rate, the following is obtained: in, , , is the nonlinear correction coefficient; make = * , = * , ,have to: When the detector working condition changes, the error b0 under different working conditions is corrected according to the calibrated blackbody spectrum value while b1 and b2 remain unchanged, so as to realize the correction of non-ideal path radiation.

[0011] According to an embodiment of the present invention, during radiation calibration, obtaining nonlinear interference data of the detector further includes: When calibrating the ground thermal vacuum radiation before the launch of the probe, various working conditions are simulated according to the on-orbit environment. Under each working condition, several cold black bodies and a variable temperature hot black body are set. Multiple temperature points are set for the variable temperature hot black body as the black body brightness setting temperature. The detector response data is obtained by rotating the two-dimensional scanning mirror to point to the variable temperature hot black body and cold black body at different temperature points.

[0012] According to an embodiment of the present invention, a plurality of temperature points are set for a variable temperature hot black body between 200.15K and 320.15K, and a high temperature black body of 300.15K is used as a reference source during two-point calibration; Based on the response data of the detector, the nonlinearity of the detector system increases with the increase of the detector receiving energy. When the target blackbody temperature is lower than the reference source temperature, the actual response rate of the system is higher than the reference source response rate, and the calibration brightness temperature is higher than the actual brightness temperature, resulting in a brightness temperature deviation greater than zero; when the target blackbody temperature is higher than the reference source temperature, the actual response rate of the system is lower than the reference source response rate, and the calibration brightness temperature is lower than the actual brightness temperature, resulting in a brightness temperature deviation less than zero. Select black bodies with a temperature of 200.15K to 320.15K under all working conditions, solve the non-ideal radiation correction coefficient under each working condition, and take the average value as the non-ideal radiation correction coefficient of the target black body.

[0013] A nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation, comprising: The nonlinear correction module is used to obtain the nonlinear interference data of the detector during radiation calibration, and to make a preliminary correction to the original spectrum of the detection target based on the response rate nonlinear correction algorithm to obtain the nonlinear correction spectrum response rate; The two-point calibration module is used to construct a linear calibration model through a two-point calibration algorithm during on-orbit operation. Based on the linear calibration model, the spectral response rate of the detector and the theoretical radiation spectrum of the observed target are obtained; A non-ideal radiation correction module is used to construct a functional relationship between the radiation from a non-ideal path to the detector and the original spectrum of the detection target based on the non-linear correction spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by two-point calibration, to obtain a non-ideal path radiation correction coefficient; the radiation from the non-ideal path to the detector includes the radiation from the detection target to the detector through a non-ideal path and the radiation from the non-detection target to the detector.

[0014] A nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation, comprising: A memory and at least one processor, wherein instructions are stored in the memory, and the memory and the at least one processor are interconnected via a line; The at least one processor calls the instructions in the memory to enable the non-linear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation to perform the non-linear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation according to an embodiment of the present invention.

[0015] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: In one embodiment of the present invention, a nonlinear correction method for infrared hyperspectral remote sensing instruments for non-ideal path radiation is disclosed. In view of the fact that part of the radiation of the geostationary orbit FY-4 / GIIRS enters the detector through a non-ideal path in a complex instrument thermal environment, during radiation calibration, nonlinear interference data of the detector is obtained, and based on a response rate nonlinear correction algorithm, a preliminary correction is made to the original spectrum of the detection target to obtain a nonlinear corrected spectral response rate; during on-orbit operation, a linear calibration model is constructed through a two-point calibration algorithm, and based on the linear calibration model, the spectral response rate of the detector and the theoretical radiation spectrum of the observed target are obtained; based on the nonlinear corrected spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by the two-point calibration, a functional relationship between the radiation reaching the detector through a non-ideal path and the original spectrum of the detection target is constructed to obtain a non-ideal path radiation correction coefficient, and further nonlinear correction is performed to eliminate non-ideal radiation errors that cannot be corrected by partial response rate nonlinear correction, thereby improving the radiation calibration accuracy of the target blackbody. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A flow chart of a nonlinear correction method for infrared hyperspectral remote sensing instruments for non-ideal path radiation in one embodiment of the present invention; Figure 2 is a schematic diagram of a nonlinear spectrum in one embodiment of the present invention; Figure 3 It is a schematic diagram of brightness temperature deviation of all pixels TVAC1-TVAC5 in the range of 200-320K of the observed target brightness temperature in one embodiment of the present invention before and after single wave number correction based on response rate nonlinearity; Figure 4 This is a schematic diagram of the original spectral residuals of all pixels of single wave numbers TVAC1-TVAC5 after nonlinear correction based on response rate in one embodiment of the present invention; Figure 5 It is a schematic diagram of brightness temperature deviation after non-ideal radiation correction based on nonlinear correction of response rate for all pixels of single wave number TVAC1-TVAC5 for the observed target brightness temperature 200-320K in one embodiment of the present invention; Figure 6Schematic diagram of the fitting values ​​and average values ​​of the long-wave non-ideal path radiation correction coefficients b2 and b1 of TVC1-TVAC5 in one embodiment of the present invention; Figure 7 A schematic diagram showing a comparison of brightness temperatures of TVAC1-TVAC5 in one embodiment of the present invention respectively using a high temperature calibration source, NL correction, and X correction method; Figure 8 This is a schematic diagram showing a comparison of brightness temperature deviations of TVAC1-TVAC5 in one embodiment of the present invention using a high temperature calibration source, NL correction, and X correction method, respectively; Fig. 9 This is a schematic diagram of the average brightness temperature deviation of all pixels after non-ideal radiation correction for the target brightness temperature range of 200K-320K observed by TVAC1-TVAC5 in one embodiment of the present invention; Fig.10 This is a schematic diagram of the average brightness temperature deviation of the target brightness temperature 280K observed by TVAC1-TVAC5 in one embodiment of the present invention after non-ideal radiation correction; Fig.11 It is a schematic diagram of a nonlinear correction device for an infrared hyperspectral remote sensing instrument for non-ideal radiation path in one embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following is a further detailed description of a nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0018] First embodiment This embodiment provides a nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation. Figure 1 , the method comprising: During radiation calibration, the nonlinear interference data of the detector is obtained, and based on the nonlinear correction algorithm of the response rate, the original spectrum of the detection target is preliminarily corrected to obtain the nonlinear correction spectrum response rate; During on-orbit operation, a linear calibration model is constructed through a two-point calibration algorithm. Based on the linear calibration model, the spectral response rate of the detector and the theoretical radiation spectrum of the observed target are obtained; Based on the nonlinear correction spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by two-point calibration, a functional relationship between the radiation reaching the detector through the non-ideal path and the original spectrum of the detection target is constructed, and the non-ideal path radiation correction coefficient is obtained for further nonlinear correction.

[0019] The above method takes into account the non-ideal path radiation of the target original spectrum, eliminates the non-ideal radiation error that cannot be corrected by the partial response rate nonlinear correction, and updates the correction coefficient under different working conditions according to the calibration blackbody spectrum value, thereby improving the radiation calibration accuracy of the target blackbody.

[0020] Specifically, the detector of this embodiment adopts the GIIRS long-wave detector. GIIRS is a time-modulated Fourier change spectrometer. The long-wave detection range of 680-1130cm-1 uses a photoconductive (PC) type mercury cadmium telluride (HgCdTe) detector. Due to the carrier lifetime problem, the MCT detector will have a more obvious nonlinear phenomenon when the number of incident photons is greater than 1019photonscm-2s-1. During radiation calibration, the infrared light radiated by the black body is converged through the collimated optical path and incident on the detector. At this time, the number of incident photons is greater than the above-mentioned MCT detector threshold, and nonlinear interference data is obtained. The detector obtains the photon flux using To indicate that the system response at this time It can be expressed as: (1) That is, the actual measurement interference data obtained by the detector, is the nonlinear coefficient. In this system, the third order and above have little effect, and generally only the second order nonlinearity is considered. The GIIRS detector amplifier circuit design uses AC coupling to amplify the signal, so the output signal does not contain a DC component, that is: (2) is the output of the nonlinear system after DC isolation, , are the DC and AC quantities of the output signal respectively. According to the Fourier spectrometer spectroscopic principle, the interference pattern and the original spectrum are Fourier transforms of each other, and the output signal can be obtained by Fourier transforming: (3) Output spectrum for nonlinear systems, is an ideal linear spectrum. The quadratic nonlinearity is manifested as a nonlinear factor and a self-convolution term (the self-convolution term only causes out-of-band distortion). The nonlinear spectrum self-convolution caused by the second harmonic term is distributed in the low frequency band and the 2-fold frequency band (the distribution range is approximately: 0-500cm-1, 1300-2340cm-1), such as Figure 2To detect the original spectrum output by the nonlinear system with target blackbody brightness temperature of 200K, 260K, and 320K. Ignoring the self-convolution term that will not affect the in-band spectrum, it can be seen from Formula 3 that there is an overall coefficient scaling of the in-band effective spectrum, and the nonlinear correction can be simplified to: (4) In this embodiment, the in-band spectrum is first corrected using a method based on response rate nonlinearity correction. The nonlinearity caused by the detector's own characteristics and the amplifier circuit is corrected. At this time, the response rate can be expressed by the original spectrum of the detected target: (5) is the spectral response rate used for preliminary calibration, To detect the original spectrum integration of the target, , is the nonlinear correction coefficient.

[0021] The original spectrum of the Fourier transform infrared hyperspectral remote sensing instrument detector is formed in the following ways: the detection target radiation reaches the detector through an ideal optical path, the detection target radiation reaches the detector due to non-ideal optical paths such as secondary reflection, scattering and diffraction, the non-detection target, i.e. the self-heating radiation of the optical device inside the instrument reaches the detector through interference, the non-detection target directly reaches the detector without interference, and various noise items. The detection target radiation reaching the detector through non-ideal paths and the non-detection target radiation reaching the detector are both non-ideal path radiation.

[0022] GIIRS in orbit calculates the calibration coefficient by measuring the high and low temperature calibration source, and converts the observed spectrum digital value into a radiance value with physical meaning. Assuming an ideal linear system and constant radiation in the instrument, ignoring the influence of noise, the following calibration model is constructed: (6) (7) (8) , , They are the original spectra generated by Fourier transform of the high-temperature calibration source, low-temperature calibration source, and the observed target interference pattern. , , The theoretical radiation spectra of the high-temperature calibration source, low-temperature calibration source and observation target, is the constant internal radiation of the instrument, and R is the spectral response rate of the linear system instrument. According to formulas 1, 2, and 3, the spectral response rate of the instrument and the observed target radiation spectrum can be obtained: (9) (10) Taking into account that the spectral response rate in the actual system is not constant and the non-ideal radiation superimposed on the original spectrum of the detection target, the relationship between the non-ideal path radiation and the original spectrum is established based on the nonlinear correction based on the response rate correction: (11) (12) is the radiation value of the target entering the detector through a non-ideal path, is the radiation correction factor for the non-ideal incident path, which represents the relationship between the original spectral integral and the non-ideal radiation. It is a fixed error of the detector under a certain working condition that cannot be corrected by two-point calibration. is the nonlinear correction response rate, , Based on the response rate nonlinear correction coefficient, combined with the above formula, we get: (13) make = * , = * , have to: (14) When the working conditions change, The theory remains unchanged. Assuming it remains unchanged, the influence of assuming it remains unchanged can be converted into the coefficient , the error b0 under different working conditions can be corrected according to the calibrated blackbody spectrum value to achieve the correction of non-ideal path radiation.

[0023] In order to verify the effectiveness of the above method, this embodiment performs the following algorithm verification and result analysis: The FY-4B GIIRS pre-launch thermal vacuum (TVAC) radiation calibration test data was selected for model verification. As shown in Table 1, five different environmental conditions are set according to the on-orbit environment simulation. Under each TVC condition, there is an 80K cold blackbody and a variable temperature hot blackbody. The variable temperature hot blackbody is set at 200.15K-320.15K, with a total of 20 temperature points. The above temperature points are the brightness temperature of the blackbody setting. The brightness temperature data after the blackbody emissivity is calibrated wavenumber by wavenumber is used in the actual calculation. The two-dimensional scanning mirror is rotated to point to the blackbody and the cold blackbody at different temperature points to obtain the instrument response.

[0024] Table 1 Ground thermal vacuum radiation calibration test conditions According to the instrument response, the following Figure 3 The curves shown, among which the gray part around the red curve is the single-wavenumber calibrated brightness temperature difference of 128 pixels under all working conditions calibrated only by the blackbody reference source, and the red curve is the mean of the calibrated brightness temperature difference; the gray part around the green curve is the single-wavenumber calibrated brightness temperature difference of 128 pixels after the nonlinear correction based on the response rate (hereinafter referred to as NL correction) for all working conditions, and the green curve is the mean of the calibrated brightness temperature difference.

[0025] Figure 3 In the figure, the dark red curve is the average single wave number brightness temperature difference of the target brightness temperature observed under all working conditions, 200.15-320.15K, and 128 pixels excluding individual defective pixels calibrated using a high temperature black body reference source. The dark green curve is the average brightness temperature difference of all pixels calibrated under a single wave number after using a nonlinear correction method based on response rate (hereinafter referred to as NL correction), and the gray curve is the brightness temperature difference of all calibration methods. The two-point calibration uses a 300.15K high temperature black body as the reference source. The nonlinearity of the system increases with the increase of the received energy of the MCT detector. When the target black body temperature is lower than the reference source temperature, the actual response rate of the system is higher than the reference source response rate, and the calibrated brightness temperature will be higher than the actual brightness temperature, resulting in a brightness temperature deviation greater than zero. When the black body temperature is higher than the reference source temperature, the actual response rate of the system is lower than the reference source response rate, and the calibrated brightness temperature is lower than the actual brightness temperature, resulting in a brightness temperature deviation less than zero. In the figure, the brightness temperature deviation after NL correction has an obvious functional relationship with the actual brightness temperature of the black body, because at this time, some non-ideal radiation is still included in the original spectrum after the initial nonlinear correction. According to formula 14, the original spectrum is separated, and the non-ideal radiation has an obvious functional relationship with the detection target spectrum integral, such as REF _Ref184506687 \h Figure 4 The non-ideal path radiation correction (hereinafter referred to as X correction) is performed on the black body, as shown in Figure 5 The blue curve is the calibration result of non-ideal radiation correction for all pixels under all working conditions with the brightness temperature of the observed target ranging from 200.15 to 320.15K. The functional relationship is weakened after correction, and the long-wave full-band calibration brightness temperature difference is significantly improved under all working conditions and all observed target brightness temperatures.

[0026] Select 200.15K-320.15K black body under all working conditions to solve the long-wave non-ideal radiation correction coefficient. The working conditions change. , Constant, take the average of the working conditions as the correction factor, under each working condition The calculation is performed using the 300.15K blackbody spectrum data of the same temperature blackbody as the on-orbit high-temperature reference source. Figure 6is the correction coefficient for all working conditions, and the average value of all working conditions is taken to obtain the average non-ideal radiation correction coefficient.

[0027] Formulas 5, 10, and 14 are used to perform two-point radiation calibration, nonlinear correction based on response rate, and non-ideal radiation correction, respectively. Figure 7 The long-wave radiation calibration results of the FOV-73 probe under all working conditions with the observed target temperatures of 260.15K, 280.15K, and 320.15K. The black dotted line is the actual brightness temperature of the measured black body, the gray background is the calibrated brightness temperature under all working conditions, and the solid lines of different colors are the average values ​​of the calibrated brightness temperatures under different working conditions using the three methods. Figure 8 The long-wave radiation calibration deviation of FOV-73 detector under all working conditions with experimental temperatures of 260.15K, 280.15K, and 320.15K. The gray background is the radiation calibration deviation under all working conditions, and the solid lines of different colors are the average values ​​of the radiation calibration deviations of the three methods under different working conditions. It can be seen from the figure that the calibration result after NL correction is closer to the actual brightness temperature of the black body, but at 700cm -1 -1000cm -1 In the wave number range, when the observed black body temperature is less than 300.15K, it deviates downward from the actual brightness temperature, and when the observed black body temperature is less than 300.15K, it deviates upward from the actual brightness temperature. The calibration result in this wave number range contains a large non-ideal radiation error. After non-ideal radiation correction, the calibration result is more in line with the actual brightness temperature of the black body, and at 700cm -1 -1000cm -1 The calibration results of non-ideal radiation correction in the wave number range are all less than 0.4K. Figure 8 shown.

[0028] Fig. 9 After correction for non-ideal path radiation, the average brightness temperature deviation of all pixels in all working conditions of TVAC1-TVAC5 observation target brightness temperature 200-320K. The calibration deviation of 200-235K is better than 0.4K except for some channels with low response rate, and the calibration deviation of all channels from 240K to 320K can be improved to 0.4K. Fig.10 For the 280K observation target, the average calibrated brightness temperature deviation of all pixels in all working conditions is better than 0.4K except for some channels with low response rate.

[0029] In summary, high-precision interferometric infrared detector data is a necessary condition for the quantitative application of satellite remote sensing data, and comprehensive system nonlinear correction is a key step in improving the accuracy of radiation calibration. This embodiment derives a correction model for the non-ideal radiation components in the original spectrum to eliminate the non-linear errors caused by non-ideal radiation. Using the pre-launch TVA calibration experimental data to verify, the algorithm has significantly improved the radiation calibration accuracy for different environmental conditions and different observation target brightness temperatures. The calibration deviation of 200-235K is better than 0.4K except for some channels with low response rates, and the average calibration accuracy of all channels from 240-320K can be improved to 0.4K.

[0030] Second embodiment Based on the same concept, this embodiment provides a nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation, including: The nonlinear correction module is used to obtain the nonlinear interference data of the detector during radiation calibration, and to make a preliminary correction to the original spectrum of the detection target based on the response rate nonlinear correction algorithm to obtain the nonlinear correction spectrum response rate; The two-point calibration module is used to construct a linear calibration model through a two-point calibration algorithm during on-orbit operation. Based on the linear calibration model, the spectral response rate of the detector and the theoretical radiation spectrum of the observed target are obtained; The non-ideal radiation correction module is used to construct a functional relationship between the radiation from the non-ideal path to the detector and the original spectrum of the detection target based on the non-linear correction spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by two-point calibration, to obtain the non-ideal path radiation correction coefficient; the radiation from the non-ideal path to the detector includes the radiation from the non-ideal path of the detection target to the detector and the radiation from the non-detection target to the detector.

[0031] The nonlinear correction algorithm adopted by the device is as described in the first embodiment and will not be described again here.

[0032] Third embodiment The above-mentioned embodiment 2 describes in detail the nonlinear correction device of the infrared hyperspectral remote sensing instrument for non-ideal radiation path of the present invention from the perspective of modular functional entities. The following describes in detail the nonlinear correction device of the infrared hyperspectral remote sensing instrument for non-ideal radiation path of the present invention from the perspective of hardware processing.

[0033] Please see Fig.11The infrared hyperspectral remote sensing instrument nonlinear correction device 500 for non-ideal path radiation may have relatively large differences due to different configurations or performances, and may include one or more processors (central processing units, CPU) 510 (for example, one or more processors) and a memory 520, and one or more storage media 530 (for example, one or more mass storage devices) storing application programs 533 or data 532. Among them, the memory 520 and the storage medium 530 can be short-term storage or permanent storage. The program stored in the storage medium 530 may include one or more modules (not shown in the figure), and each module may include a series of instruction operations in the infrared hyperspectral remote sensing instrument nonlinear correction device 500 for non-ideal path radiation.

[0034] Furthermore, the processor 510 may be configured to communicate with the storage medium 530 to execute a series of instruction operations in the storage medium 530 on the infrared hyperspectral remote sensing instrument nonlinear correction device 500 for non-ideal path radiation.

[0035] The nonlinear correction device 500 for infrared hyperspectral remote sensing instruments with non-ideal path radiation may also include one or more power supplies 540, one or more wired or wireless network interfaces 550, one or more input and output interfaces 560, and / or one or more operating systems 531, such as Windows Serve, Vista, etc.

[0036] Those skilled in the art will understand that Fig.11 The structure of the nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation shown does not constitute a limitation of the nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation, and may include more or fewer components than shown in the figure, or a combination of certain components, or a different arrangement of components.

[0037] The present invention also provides a computer-readable storage medium, which may be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium. The computer-readable storage medium stores instructions, which, when executed on a computer, cause the computer to execute the steps of the non-linear correction method for infrared hyperspectral remote sensing instruments of non-ideal path radiation in the first embodiment.

[0038] If the module in the second embodiment is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of software. The computer software is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0039] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and equipment can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0040] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation, characterized in that: include: During radiation calibration, the nonlinear interference data of the detector is obtained, and based on the nonlinear correction algorithm of the response rate, the original spectrum of the detection target is preliminarily corrected to obtain the nonlinear correction spectrum response rate; During on-orbit operation, a linear calibration model is constructed through a two-point calibration algorithm. Based on the linear calibration model, the spectral response rate of the detector and the theoretical radiation spectrum of the observed target are obtained; Based on the nonlinear correction spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by two-point calibration, a functional relationship between the radiation reaching the detector through a non-ideal path and the original spectrum of the detection target is constructed to obtain a non-ideal path radiation correction coefficient; the radiation reaching the detector through a non-ideal path includes the radiation reaching the detector through a non-ideal path of the detection target and the radiation reaching the detector through a non-detection target.

2. The nonlinear correction method for infrared hyperspectral remote sensing instrument of non-ideal path radiation according to claim 1, characterized in that: The construction of the linear calibration model by the two-point calibration algorithm further includes: For a linear system with constant radiation in the detector, the following linear calibration model is constructed: in, , , They are the original spectra generated by Fourier transform of the high-temperature calibration source, low-temperature calibration source, and the observed target interference pattern. , , are the theoretical radiation spectra of the high-temperature calibration source, low-temperature calibration source, and observation target, respectively. is the constant radiation inside the detector, and R is the spectral response rate of the linear system detector.

3. The nonlinear correction method for infrared hyperspectral remote sensing instrument of non-ideal path radiation according to claim 2, characterized in that: Based on the nonlinear correction spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detected target and the fixed error that cannot be corrected by the two-point calibration, constructing the functional relationship between the radiation reaching the detector through the non-ideal path and the original spectrum of the detected target further includes: Combining the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by two-point calibration, on the basis of non-linear correction based on response rate correction, the functional relationship between the radiation reaching the detector through the non-ideal path and the original spectrum of the detection target is constructed as follows: is the radiation value that reaches the detector through a non-ideal path. is the radiation correction factor for the non-ideal incident path, which represents the relationship between the original spectral integral and the non-ideal radiation; It is a fixed error of the detector under a certain working condition that cannot be corrected by two-point calibration; is the nonlinear corrected spectral response rate; E is the integral of the original spectrum of the detection target.

4. The nonlinear correction method for infrared hyperspectral remote sensing instrument of non-ideal path radiation according to claim 3, characterized in that: Based on the functional relationship between the radiation reaching the detector through the non-ideal path and the original spectrum of the detection target, combined with the calculation formula of the nonlinear correction spectrum response rate, we get: in, , , is the nonlinear correction coefficient; make = * , = * , ,have to: When the detector working condition changes, the error b0 under different working conditions is corrected according to the calibrated blackbody spectrum value while b1 and b2 remain unchanged, so as to realize the correction of non-ideal path radiation.

5. The nonlinear correction method for infrared hyperspectral remote sensing instrument of non-ideal path radiation according to claim 1, characterized in that: During radiation calibration, obtaining nonlinear interference data of the detector further includes: When calibrating the ground thermal vacuum radiation before the launch of the probe, various working conditions are simulated according to the on-orbit environment. Under each working condition, several cold black bodies and a variable temperature hot black body are set. Multiple temperature points are set for the variable temperature hot black body as the black body brightness setting temperature. The detector response data is obtained by rotating the two-dimensional scanning mirror to point to the variable temperature hot black body and cold black body at different temperature points.

6. The nonlinear correction method for infrared hyperspectral remote sensing instrument of non-ideal path radiation according to claim 5, characterized in that: Set multiple temperature points for the variable temperature hot black body between 200.15K and 320.15K. When calibrating at two points, use the high temperature black body of 300.15K as the reference source. Based on the response data of the detector, the nonlinearity of the detector system increases with the increase of the detector receiving energy. When the target blackbody temperature is lower than the reference source temperature, the actual response rate of the system is higher than the reference source response rate, and the calibration brightness temperature is higher than the actual brightness temperature, resulting in a brightness temperature deviation greater than zero; when the target blackbody temperature is higher than the reference source temperature, the actual response rate of the system is lower than the reference source response rate, and the calibration brightness temperature is lower than the actual brightness temperature, resulting in a brightness temperature deviation less than zero. Select black bodies with a temperature of 200.15K to 320.15K under all working conditions, solve the non-ideal radiation correction coefficient under each working condition, and take the average value as the non-ideal radiation correction coefficient of the target black body.

7. A nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal radiation paths, characterized in that: include: The nonlinear correction module is used to obtain the nonlinear interference data of the detector during radiation calibration, and to make a preliminary correction to the original spectrum of the detection target based on the response rate nonlinear correction algorithm to obtain the nonlinear correction spectrum response rate; The two-point calibration module is used to construct a linear calibration model through a two-point calibration algorithm during on-orbit operation. Based on the linear calibration model, the spectral response rate of the detector and the theoretical radiation spectrum of the observed target are obtained; A non-ideal radiation correction module is used to construct a functional relationship between the radiation from a non-ideal path to the detector and the original spectrum of the detection target based on the non-linear correction spectral response rate and the theoretical radiation spectrum of the observed target, combined with the non-ideal radiation superimposed on the original spectrum of the detection target and the fixed error that cannot be corrected by two-point calibration, to obtain a non-ideal path radiation correction coefficient; the radiation from the non-ideal path to the detector includes the radiation from the detection target to the detector through a non-ideal path and the radiation from the non-detection target to the detector.

8. A nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal radiation paths, characterized in that: include: A memory and at least one processor, wherein instructions are stored in the memory, and the memory and the at least one processor are interconnected via a line; The at least one processor calls the instructions in the memory to enable the non-linear correction device of the infrared hyperspectral remote sensing instrument for non-ideal path radiation to execute the non-linear correction method of the infrared hyperspectral remote sensing instrument for non-ideal path radiation as described in any one of claims 1-6.

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