Nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation

Abstract

This invention discloses a nonlinear correction method for infrared hyperspectral remote sensing instruments that receive radiation via nonideal paths. Addressing the issue that some radiation from geostationary GIIRS enters the detector via nonideal paths under complex thermal environments, the method initially corrects the original spectrum of the target during radiometric calibration using a nonlinear responsivity correction algorithm. During on-orbit operation, a linear calibration model is constructed using a two-point calibration algorithm to obtain the detector's spectral responsivity and the theoretical radiation spectrum of the observed target. Based on the nonlinearly corrected spectral responsivity and the theoretical radiation spectrum of the observed target, and considering the nonideal radiation superimposed on the original spectrum of the target and the fixed errors that cannot be corrected by two-point calibration, a functional relationship is constructed between the radiation arriving at the detector via nonideal paths and the original spectrum of the target. This yields a nonideal path radiation correction coefficient, which is then further used for nonlinear correction to eliminate nonideal radiation errors that cannot be corrected by the responsivity nonlinear correction, thereby improving the radiometric calibration accuracy of the target blackbody.

Description

Technical Field

[0001] This invention belongs to the technical field of infrared detectors, and particularly relates to a nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation paths. Background Technology

[0002] The interferometric infrared detector carried by the Fengyun-4 satellite is the world's first Fourier transform infrared hyperspectral remote sensing instrument in geostationary orbit to detect the three-dimensional vertical structure of the atmosphere using interferometric spectroscopy. Its remote sensing data is of great significance for improving numerical weather prediction models and enhancing the prediction accuracy of extreme weather events. For quantitative applications, accurate calibration results are a necessary condition, and nonlinear correction is a key step in improving radiometric calibration accuracy. Nonlinearity is a comprehensive characteristic of complex systems, closely related to various factors such as the photoelectric properties of detector materials, the design architecture of the detection circuit, the design and components of the optical system, the complex background temperature of the instrument, changes in the instrument's emission and on-orbit operating states, and component attenuation. It describes the nonlinear relationship between the detector's output electrical signal and the system's input optical power.

[0003] Nonlinearity introduced by optical systems is often limited by optimizing the system structure. This includes optimizing optical shielding elements, controlling the surface quality and cleanliness of optical components, setting specific optical compensation components, and designing flexible stray light suppression mechanisms according to requirements. Nonlinearity caused by the photoelectric properties of detector materials and the design architecture of the detection circuit is eliminated by modifying the circuit design. For example, an interferometer with a dual-output structure eliminates nonlinear signals by combining two outputs with the same amplitude but opposite phase. Alternatively, a nonlinearity correction circuit is proposed to reduce the influence of series resistance in the photoconductive detector circuit. Adding positive feedback to the detection circuit further reduces series resistance nonlinearity, or changing the constant current bias of the HgCdTe detector to a constant voltage bias suppresses circuit nonlinearity. However, these hardware correction methods have poor adaptability because they only address nonlinearity correction for a specific structure.

[0004] For spaceborne time-modulated Fourier transform hyperspectral infrared remote sensing instruments, correction is often performed considering the system's second-order nonlinearity. This involves modeling the detector's received light intensity and the system's nonlinear response to achieve the correction. For example, autocorrelation functions are used to detect and eliminate the detector's nonlinear response. On FY-3D HIRAS, the ideal linear system response is used as a constant to solve for the correction coefficients and remove nonlinearity. Alternatively, based on the above methods, several specific methods for obtaining interferogram directivity and for converging nonlinear coefficients have been refined.

[0005] Based on the response rate nonlinear correction method, this invention further considers the impact of target radiation entering the detector through non-ideal paths, taking into account the uneven distribution of sunlight on the orbit of the FY-4 / GIIRS geostationary orbit interferometric infrared detector and the drastic daily temperature changes of the instrument. The invention then performs nonlinear correction on the system. Summary of the Invention

[0006] The purpose of this invention is to provide a nonlinear correction method for infrared hyperspectral remote sensing instruments that emit radiation via non-ideal paths. Specifically, for the FY-4 / GIIRS in geostationary orbit, under complex instrument thermal conditions, some radiation enters the detector via non-ideal paths. By establishing a computational model, the non-ideal incident path correction coefficient is solved in the spectral dimension to perform nonlinear correction, eliminating some non-ideal radiation errors that cannot be corrected by nonlinear correction of the response rate, thereby improving the radiometric calibration accuracy of the target blackbody.

[0007] To solve the above problems, the technical solution of the present invention is as follows:

[0008] A nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation pathways includes:

[0009] During radiometric calibration, nonlinear interferometric data of the detector is acquired, and the original spectrum of the target is initially corrected based on the nonlinear response rate correction algorithm to obtain the nonlinear corrected spectral response rate.

[0010] During in-orbit operation, a linear calibration model is constructed using a two-point calibration algorithm. Based on the linear calibration model, the spectral responsivity of the detector and the theoretical radiation spectrum of the observed target are obtained.

[0011] 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 two-point calibration, a functional relationship between the radiation reaching the detector through a non-ideal path and the original spectrum of the detected target is constructed, and the non-ideal path radiation correction coefficient is obtained; the radiation reaching the detector through a non-ideal path includes the radiation of the detected target reaching the detector through a non-ideal path and the radiation of non-detected targets reaching the detector.

[0012] According to an embodiment of the present invention, the construction of a linear calibration model using a two-point calibration algorithm further includes:

[0013] For a linear system, assuming constant radiation within the detector, the following linear calibration model is constructed:

[0014]

[0015]

[0016]

[0017] in, , , These are the original spectra generated by Fourier transforming the interferograms of the high-temperature calibration source, the low-temperature calibration source, and the observed target, respectively. , , These are the theoretical radiation spectra of the high-temperature calibration source, the low-temperature calibration source, and the observed target, respectively. R represents the radiation within the constant detector, and R is the spectral responsivity of the linear system detector.

[0018] According to an embodiment of the present invention, based on the nonlinear correction spectral response and the theoretical radiation spectrum of the observed target, and combined with the non-ideal radiation superimposed on the original spectrum of the detected target and the fixed error that cannot be corrected by two-point calibration, the functional relationship between the radiation reaching the detector through a non-ideal path and the original spectrum of the detected target is further constructed as follows:

[0019] Considering the non-ideal radiation superimposed from the original spectra of the target and the fixed errors that cannot be corrected by two-point calibration, based on nonlinear correction using responsivity correction, the functional relationship between the radiation reaching the detector via a non-ideal path and the original spectrum of the target is constructed as follows:

[0020]

[0021]

[0022] The radiation level that the target reaches the detector via a non-ideal path. For non-ideal incident path radiation correction coefficient, it represents the relationship between the original spectral integral and non-ideal radiation; This refers to a fixed error that cannot be corrected by two-point calibration of the detector under a certain operating condition. denoted as the nonlinear correction spectral responsivity; E is the integral of the original spectrum of the target being detected.

[0023] According to one embodiment of the present invention, based on the functional relationship between the radiation reaching the detector via a non-ideal path and the original spectrum of the target, and combined with the calculation formula for the nonlinear correction spectral responsivity, the following is obtained:

[0024]

[0025] in, , , These are nonlinear correction coefficients;

[0026] make = * , = * , ,have to:

[0027]

[0028] When the detector's operating conditions change, while b1 and b2 remain unchanged, the error b0 under different operating conditions is corrected based on the calibrated blackbody spectral value to achieve correction of non-ideal path radiation.

[0029] According to one embodiment of the present invention, acquiring the nonlinear interferometric data of the detector during radiation calibration further includes:

[0030] During the ground thermal vacuum radiation calibration before the probe is launched, various working conditions are simulated based on the on-orbit environment. Under each working condition, several cold blackbodies and one variable-temperature hot blackbodies are set. Multiple temperature points are set for the variable-temperature hot blackbodies to serve as the brightness temperature of the blackbodies.

[0031] By rotating a two-dimensional scanning mirror to point at different temperature points, the detector response data is obtained.

[0032] According to one embodiment of the present invention, multiple temperature points are set for the variable-temperature thermal blackbody between 200.15K and 320.15K, and a high-temperature blackbody of 300.15K is used as the reference source when calibrating at two points.

[0033] Based on the detector's response data, it was found that the nonlinearity of the detector system increases with the increase of the energy received by the detector. When the target blackbody temperature is lower than the reference source temperature, the actual response rate of the system is greater than the reference source response rate, and the calibrated brightness temperature is greater than the actual brightness temperature, resulting in a brightness temperature deviation greater than zero. When the target blackbody temperature is greater than the reference source temperature, the actual response rate of the system is less than the reference source response rate, and the calibrated brightness temperature is less than the actual brightness temperature, resulting in a brightness temperature deviation less than zero.

[0034] Select a blackbody at 200.15K~320.15K under all working conditions, solve for 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 blackbody.

[0035] A nonlinear correction device for infrared hyperspectral remote sensing instruments emitting radiation via non-ideal pathways includes:

[0036] The nonlinear correction module is used to acquire the nonlinear interferometric data of the detector during radiometric calibration, and to perform preliminary correction on the original spectrum of the target based on the nonlinear response rate correction algorithm to obtain the nonlinear corrected spectral response rate.

[0037] The two-point calibration module is used during on-orbit operation to construct a linear calibration model using a two-point calibration algorithm. Based on the linear calibration model, the spectral responsivity of the detector and the theoretical radiation spectrum of the observed target are obtained.

[0038] The non-ideal radiation correction module is used to construct a functional relationship between the radiation reaching the detector via a non-ideal path and the original spectrum of the 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 target and the fixed error that cannot be corrected by two-point calibration, to obtain the non-ideal path radiation correction coefficient; the radiation reaching the detector via a non-ideal path includes the radiation from the target reaching the detector via a non-ideal path and the radiation from non-targets reaching the detector.

[0039] A nonlinear correction device for infrared hyperspectral remote sensing instruments emitting radiation via non-ideal pathways, comprising:

[0040] A memory and at least one processor, wherein the memory stores instructions and the memory and the at least one processor are interconnected via a circuit;

[0041] The at least one processor invokes the instructions in the memory to cause the nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation to execute a nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation according to an embodiment of the present invention.

[0042] Because the present invention adopts the above technical solution, it has the following advantages and positive effects compared with the prior art:

[0043] One embodiment of the present invention provides a nonlinear correction method for infrared hyperspectral remote sensing instruments that addresses the issue of some radiation entering the detector via non-ideal paths under complex instrument thermal conditions in geostationary FY-4 / GIIRS. During radiometric calibration, nonlinear interferometric data of the detector is acquired, and the original spectrum of the target is initially corrected based on a nonlinear response rate correction algorithm to obtain a nonlinearly corrected spectral response rate. During on-orbit operation, a linear calibration model is constructed using 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 nonlinearly 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 target and the fixed errors that cannot be corrected by two-point calibration, a functional relationship between the radiation reaching the detector via non-ideal paths and the original spectrum of the target is constructed to obtain the non-ideal path radiation correction coefficient. Further nonlinear correction is then performed to eliminate some non-ideal radiation errors that cannot be corrected by the nonlinear response rate correction, thereby improving the radiometric calibration accuracy of the target blackbody. Attached Figure Description

[0044] Figure 1This is a flow chart of a nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation pathways, according to one embodiment of the present invention.

[0045] Figure 2 This is a schematic diagram of a nonlinear spectrum in one embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the brightness temperature deviation of all pixels in the brightness temperature range of 200-320K (TVAC1-TVAC5) of the observed target before and after nonlinear correction based on the response rate in one embodiment of the present invention.

[0047] Figure 4 This is a schematic diagram of the original spectral residuals of all pixels of TVAC1-TVAC5 single wavenumbers after nonlinear correction based on response rate in one embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram of the brightness temperature deviation after non-ideal radiation correction for all pixels of TVAC1-TVAC5 single wavenumbers with a target brightness temperature of 200-320K in one embodiment of the present invention, based on non-linear correction of the response rate.

[0049] Figure 6 This is a schematic diagram showing the fitted values ​​and average values ​​of the long-wavelength non-ideal path radiation correction coefficients b2 and b1 for TVAC1-TVAC5 in one embodiment of the present invention.

[0050] Figure 7 This is a schematic diagram showing the comparison of brightness temperatures of TVAC1-TVAC5 calibrated using high-temperature calibration source, NL correction, and X correction methods in one embodiment of the present invention.

[0051] Figure 8 This is a schematic diagram showing the comparison of brightness temperature deviations of TVAC1-TVAC5 calibrated using high-temperature calibration source, NL correction, and X correction methods in one embodiment of the present invention.

[0052] Figure 9 This is a schematic diagram of the average brightness temperature deviation of all pixels in the brightness temperature range of 200K-320K observed by TVAC1-TVAC5 in one embodiment of the present invention after non-ideal radiation correction.

[0053] Figure 10 This is a schematic diagram of the average brightness temperature deviation of the TVAC1-TVAC5 observed targets after non-ideal radiation correction at a brightness temperature of 280K in one embodiment of the present invention.

[0054] Figure 11 This is a schematic diagram of a nonlinear correction device for an infrared hyperspectral remote sensing instrument with non-ideal radiation pathways, according to an embodiment of the present invention. Detailed Implementation

[0055] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for nonlinear correction of infrared hyperspectral remote sensing instruments based on non-ideal radiation pathways, as proposed in this invention. The advantages and features of this invention will become more apparent from the following description and claims.

[0056] First Embodiment

[0057] This embodiment provides a nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation pathways. Please refer to [link / reference]. Figure 1 The method includes:

[0058] During radiometric calibration, nonlinear interferometric data of the detector is acquired, and the original spectrum of the target is initially corrected based on the nonlinear response rate correction algorithm to obtain the nonlinear corrected spectral response rate.

[0059] During in-orbit operation, a linear calibration model is constructed using a two-point calibration algorithm. Based on the linear calibration model, the spectral responsivity of the detector and the theoretical radiation spectrum of the observed target are obtained.

[0060] 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 two-point calibration, a functional relationship between the radiation reaching the detector through a non-ideal path and the original spectrum of the detected target is constructed, and the non-ideal path radiation correction coefficient is obtained, which is then further used for nonlinear correction.

[0061] The above method takes into account the non-ideal path radiation of the original target spectrum, eliminates some non-ideal radiation errors that cannot be corrected by nonlinear response correction, and updates the correction coefficients under different working conditions based on the calibrated blackbody spectral values, thereby improving the radiation calibration accuracy of the target blackbody.

[0062] Specifically, this embodiment uses a GIIRS long-wavelength detector, which is a time-modulated Fourier transform spectrometer. The long-wavelength detection range of 680-1130 cm⁻¹ uses a photoconductive (PC) type mercury cadmium telluride (HgCdTe) detector. Due to carrier lifetime limitations, the MCT detector exhibits significant nonlinearity when the number of incident photons exceeds 10¹⁹ photons cm⁻² s⁻¹. During radiometric calibration, the infrared light emitted by the blackbody is collimated and focused onto the detector. At this point, the number of incident photons exceeds the aforementioned MCT detector threshold, allowing for the acquisition of nonlinear interference data. The detector acquires photon flux using... This indicates the system response at this time. It can be represented as:

[0063] (1)

[0064] This refers to the actual measurement interference data acquired by the detector. For nonlinear coefficients, the influence of third and higher orders is relatively small in this system; generally, only second-order nonlinearity is considered. The GIIRS detector amplifier circuit design uses AC coupling to amplify the signal, therefore the output signal does not contain a DC component, i.e.:

[0065] (2)

[0066] The output of the nonlinear system after DC blocking. , These represent the DC and AC output signals, respectively. According to the principle of Fourier spectrometry, the interferogram and the original spectrum are Fourier transforms of each other. Therefore, performing a Fourier transform on the output signal yields the following:

[0067] (3)

[0068] For the output spectrum of a nonlinear system, The spectrum is ideally linear. The second-order nonlinearity manifests as a nonlinear factor and a self-convolution term (which only causes out-of-band distortion). The self-convolution of the nonlinear spectrum caused by the second harmonic term is distributed in the low-frequency and second-harmonic bands (approximately 0-500 cm⁻¹, 1300-2340 cm⁻¹). Figure 2 To detect the raw spectra output by a nonlinear system with target blackbody brightness temperatures of 200K, 260K, and 320K, and ignoring the self-convolution terms that do not affect the in-band spectrum, Equation 3 shows that the effective in-band spectrum has an overall coefficient scaling. Therefore, the nonlinear correction can be simplified to:

[0069] (4)

[0070] This embodiment first uses a method based on response rate nonlinear correction to perform in-band spectroscopy. The nonlinearity caused by the detector's own characteristics and the amplification circuit is corrected, and the responsivity can then be expressed as the original spectrum of the detected target.

[0071] (5)

[0072] The spectral responsivity is used for initial correction. To detect the original spectral integral of the target, , This is the nonlinear correction coefficient.

[0073] The formation of the original spectrum of the detector in a Fourier transform infrared hyperspectral remote sensing instrument includes the following pathways: radiation from the target reaches the detector via an ideal optical path; radiation from the target reaches the detector via a non-ideal optical path due to secondary reflection, scattering, and diffraction; radiation from non-target objects (i.e., self-heating radiation from internal optical components of the instrument) reaches the detector via interference; radiation from non-target objects reaches the detector directly without interference; and various noise components. Both radiation from the target and radiation from non-target objects reaching the detector via non-ideal optical paths are considered non-ideal radiation paths.

[0074] GIIRS, while in orbit, calculates calibration coefficients by measuring high and low temperature calibration sources, converting observed spectral digital values ​​into physically meaningful radiance values. Assuming an ideal linear system and constant internal instrument radiation, and neglecting noise and other effects, the following calibration model is constructed:

[0075] (6)

[0076] (7)

[0077] (8)

[0078] , , These are the original spectra generated by Fourier transforming the interferograms of the high-temperature calibration source, the low-temperature calibration source, and the observed target, respectively. , , The theoretical radiation spectra of high-temperature calibration sources, low-temperature calibration sources, and observed targets. Let R be the spectral responsivity of the linear system instrument, and R be the internal radiation of the constant instrument. The instrument spectral responsivity and the radiation spectrum of the observed target can be obtained using formulas 1, 2, and 3.

[0079] (9)

[0080] (10)

[0081] Considering that the spectral responsivity in real systems is not constant and that the radiation from the superposition of the original spectra of the target is non-ideal, a relationship between the non-ideal path radiation and the original spectrum is established based on nonlinear correction using responsivity correction:

[0082] (11)

[0083] (12)

[0084] The radiation level at which the target enters the detector via a non-ideal path. The non-ideal incident path radiation correction factor represents the relationship between the original spectral integral and the non-ideal radiation. This refers to a fixed error that cannot be corrected by two-point calibration when the detector is operating under a certain condition. For nonlinear correction response rate, , Based on the nonlinearity correction coefficient of the response rate, combined with the above formula, we get:

[0085] (13)

[0086] make = * , = * , have to:

[0087] (14)

[0088] When operating conditions change, The theory remains unchanged. Assuming it remains constant, the effect of this assumption can be factored into a coefficient. This allows for the correction of error b0 under different operating conditions based on the calibrated blackbody spectral values, thereby achieving correction of non-ideal path radiation.

[0089] To verify the effectiveness of the above method, this embodiment performs the following algorithm verification and result analysis:

[0090] Model verification was performed using thermal vacuum (TVAC) radiation calibration test data from the FY-4B GIIRS pre-launch phase. As shown in Table 1, five different environmental conditions were set up based on the on-orbit environment simulation. Each TVAC condition included an 80K cold blackbody and a variable-temperature hot blackbody, with 20 temperature points ranging from 200.15K to 320.15K for the variable-temperature hot blackbody. These temperature points represent the brightness temperatures of the blackbody; the actual calculations used brightness temperature data calibrated wavenumber-by-wavelength for blackbody emissivity. The instrument response was obtained by rotating a two-dimensional scanning mirror to point at the blackbody and the cold blackbody at different temperature points.

[0091] Table 1 Ground thermal vacuum radiation calibration test conditions

[0092]

[0093] Based on the instrument response, the following can be obtained: Figure 3The curves shown are as follows: the gray area around the red curve represents the single-wavenumber calibration brightness temperature difference of 128 pixels calibrated using only a blackbody reference source under all operating conditions; the red curve represents the average calibration brightness temperature difference. The gray area around the green curve represents the single-wavenumber calibration brightness temperature difference of 128 pixels under all operating conditions after nonlinear correction based on response rate (hereinafter referred to as NL correction); the green curve represents the average calibration brightness temperature difference.

[0094] Figure 3 In the diagram, the dark red curve represents the average brightness temperature difference per wavenumber for all observed target brightness temperatures (200.15-320.15K) under all operating conditions, excluding a few defective pixels, calibrated using a high-temperature blackbody reference source. The dark green curve represents the average calibration brightness temperature difference per wavenumber for all pixels after applying a nonlinear correction method based on responsivity (hereinafter referred to as NL correction). The gray curve represents the calibration brightness temperature difference for all pixels using both methods. Two calibration points used a 300.15K high-temperature blackbody as the reference source. The system nonlinearity increases with the energy received by the MCT detector. When the target blackbody temperature is lower than the reference source temperature, the actual system responsivity is greater than the reference source responsivity, resulting in a calibration brightness temperature greater than the actual brightness temperature and a brightness temperature deviation greater than zero. Conversely, when the blackbody temperature is higher than the reference source temperature, the actual system responsivity is less than the reference source responsivity, resulting in a calibration brightness temperature less than the actual brightness temperature and a brightness temperature deviation less than zero. The brightness temperature deviation after NL correction in the figure shows a clear functional relationship with the actual brightness temperature of the blackbody. This is because, at this point, some non-ideal radiation is still included in the original spectrum after the initial nonlinear correction. According to Equation 14, the original spectrum is separated, and the non-ideal radiation has a clear functional relationship with the integral of the target spectrum, as shown in Equation 14. Figure 4 As shown. Non-ideal path radiometric correction is applied to the blackbody (hereinafter referred to as X-correction), as follows: Figure 5 The blue curve represents the non-ideal radiometric calibration results for all pixels under all operating conditions, with target brightness temperatures ranging from 200.15 to 320.15 K. The functional relationship is weakened after correction, and the calibration brightness temperature difference across the entire long-wavelength band is significantly improved under all operating conditions and target brightness temperatures.

[0095] We solve for the long-wavelength non-ideal radiation correction coefficients using a blackbody at 200.15K-320.15K under all operating conditions. As the operating conditions change... , The value is constant, and the average value of the working conditions is used as the correction factor. Under each working condition... Calculations were performed using spectral data of a 300.15K blackbody at the same temperature from an on-orbit high-temperature reference source. (e.g., REF _Ref179535722 \h) Figure 6 The average non-ideal radiation correction factor is obtained by taking the average value of all operating conditions as the correction factor for all operating conditions.

[0096] Two-point radiometric calibration, nonlinear correction based on response rate, and nonideal radiometric correction were performed using formulas 5, 10, and 14, respectively. Figure 7 The longwave radiation calibration results of the FOV-73 probe under all operating conditions with target temperatures of 260.15K, 280.15K, and 320.15K are shown. The black dashed line represents the actual brightness temperature of the measured blackbody, the gray background represents the calibrated brightness temperature under all operating conditions, and the solid lines of different colors represent the average brightness temperature calibrated under different operating conditions using the three methods. Figure 8 The graph shows the long-wave radiometric calibration deviations of the FOV-73 probe at experimental temperatures of 260.15K, 280.15K, and 320.15K under all operating conditions. The gray background represents the radiometric calibration deviations under all operating conditions, and the solid lines of different colors represent the average radiometric calibration deviations of the three methods under different operating conditions. The graph shows that the calibration results after NL correction are closer to the actual brightness temperature of the blackbody, but at 700cm... -1 -1000cm -1 Within the wavenumber range, the observed blackbody temperature deviates downwards from the actual brightness temperature when it is less than 300.15 K, and upwards from the actual brightness temperature when it is less than 300.15 K. The calibration results in this wavenumber range contain significant non-ideal radiation errors. After non-ideal radiation correction, the calibration results more closely match the actual blackbody brightness temperature, especially at 700 cm⁻¹. -1 -1000cm -1 The non-ideal radiation correction calibration results in the wavenumber range are all less than 0.4K. Figure 8 As shown.

[0097] Figure 9 After non-ideal path radiometric correction, the average brightness temperature deviation of all pixels under all operating conditions in the brightness temperature range of 200-320K observed by TVAC1-TVAC5 is as follows: The calibration deviation is better than 0.4K for all channels except some low-response channels in the 200-235K range, and the calibration deviation of all channels in the 240K-320K range can be improved to 0.4K. Figure 10 The average calibration brightness temperature deviation of all pixels under all operating conditions for the 280K observation target is better than 0.4K, except for some channels with lower response rates.

[0098] In summary, high-precision interferometric infrared detector data is essential for the quantitative application of satellite remote sensing data, and comprehensive system nonlinear correction is a key step in improving radiometric calibration accuracy. This embodiment derives a correction model to eliminate nonlinear errors caused by non-ideal radiation in the original spectrum, targeting non-ideal radiation components. Verification using pre-launch TVAC calibration experimental data shows that the algorithm significantly improves radiometric calibration accuracy for different environmental conditions and target brightness temperatures. In the 200-235K range, except for some low-response channels, the calibration deviation is better than 0.4K, and in the 240-320K range, the average calibration accuracy for all channels can be improved to 0.4K.

[0099] Second Embodiment

[0100] Based on the same concept, this embodiment provides a nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal radiation paths, comprising:

[0101] The nonlinear correction module is used to acquire the nonlinear interferometric data of the detector during radiometric calibration, and to perform preliminary correction on the original spectrum of the target based on the nonlinear response rate correction algorithm to obtain the nonlinear corrected spectral response rate.

[0102] The two-point calibration module is used during on-orbit operation to construct a linear calibration model using a two-point calibration algorithm. Based on the linear calibration model, the spectral responsivity of the detector and the theoretical radiation spectrum of the observed target are obtained.

[0103] The non-ideal radiation correction module is used to construct a functional relationship between the radiation reaching the detector via a non-ideal path and the original spectrum of the 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 target and the fixed error that cannot be corrected by two-point calibration, and to obtain the non-ideal path radiation correction coefficient. The radiation reaching the detector via a non-ideal path includes the radiation from the target via a non-ideal path and the radiation from non-targets reaching the detector.

[0104] The nonlinear correction algorithm used in this device is as described in the first embodiment and will not be repeated here.

[0105] Third Embodiment

[0106] The above embodiment 2 describes in detail the nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation from the perspective of modular functional entities. The following describes in detail the nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation from the perspective of hardware processing.

[0107] Please refer to Figure 11 The nonlinear correction device 500 for infrared hyperspectral remote sensing instruments emitting nonideal path radiation can vary considerably due to differences in configuration or performance. It may include one or more central processing units (CPUs) 510 (e.g., one or more processors) and memory 520, and one or more storage media 530 (e.g., one or more mass storage devices) for storing application programs 533 or data 532. The memory 520 and storage media 530 can be temporary or persistent storage. The program stored in the storage media 530 may include one or more modules (not shown in the figure), each module including a series of instruction operations for the nonlinear correction device 500 for infrared hyperspectral remote sensing instruments emitting nonideal path radiation.

[0108] Furthermore, the processor 510 can be configured to communicate with the storage medium 530 and execute a series of instructions stored in the storage medium 530 on the nonlinear correction device 500 of the infrared hyperspectral remote sensing instrument radiated through a non-ideal path.

[0109] The nonlinear correction device 500 for infrared hyperspectral remote sensing instruments with non-ideal radiation paths may also include one or more power supplies 540, one or more wired or wireless network interfaces 550, one or more input / output interfaces 560, and / or one or more operating systems 531, such as Windows Server, Vista, etc.

[0110] Those skilled in the art will understand that Figure 11 The illustrated structure of the nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation does not constitute a limitation on the nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation. It may include more or fewer components than illustrated, or combine certain components, or have different component arrangements.

[0111] The present invention also provides a computer-readable storage medium, which can be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium. The computer-readable storage medium stores instructions that, when executed on a computer, cause the computer to perform the steps of the nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation pathways described in Embodiment 1.

[0112] If the modules in Embodiment 2 are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in software form. This computer software is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0113] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described apparatus and equipment can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0114] The embodiments of the present invention have been described in detail above with reference to 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 shall still fall within the protection scope of the present invention.

Claims

1. A nonlinear correction method for infrared hyperspectral remote sensing instruments emitting radiation via non-ideal pathways, characterized in that, include: During radiometric calibration, nonlinear interferometric data of the detector is acquired, and the original spectrum of the target is initially corrected based on the nonlinear response rate correction algorithm to obtain the nonlinear corrected spectral response rate. During in-orbit operation, a linear calibration model is constructed using a two-point calibration algorithm. Based on the linear calibration model, the spectral responsivity 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 detected 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 detected target is constructed, and the non-ideal path radiation correction coefficient is obtained; the radiation reaching the detector through a non-ideal path includes the radiation of the detected target reaching the detector through a non-ideal path and the radiation of non-detected targets reaching the detector.

2. The nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation paths as described in claim 1, characterized in that, The construction of the linear calibration model using the two-point calibration algorithm further includes: For a linear system, assuming constant radiation within the detector, the following linear calibration model is constructed: in, , , These are the original spectra generated by Fourier transforming the interferograms of the high-temperature calibration source, the low-temperature calibration source, and the observed target, respectively. , , These are the theoretical radiation spectra of the high-temperature calibration source, the low-temperature calibration source, and the observed target, respectively. R represents the radiation within the constant detector, and R is the spectral responsivity of the linear system detector.

3. The nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation paths as described in claim 2, characterized in that, Based on the aforementioned nonlinear corrected spectral response rate and the theoretical radiation spectrum of the observed target, and considering the non-ideal radiation superimposed on the original spectrum of the target and the fixed error that cannot be corrected by two-point calibration, the functional relationship between the radiation reaching the detector via a non-ideal path and the original spectrum of the target is further constructed as follows: Considering the non-ideal radiation superimposed from the original spectra of the target and the fixed errors that cannot be corrected by two-point calibration, based on nonlinear correction using responsivity correction, the functional relationship between the radiation reaching the detector via a non-ideal path and the original spectrum of the target is constructed as follows: The radiation level that the target reaches the detector via a non-ideal path. For non-ideal incident path radiation correction coefficient, it represents the relationship between the original spectral integral and non-ideal radiation; This refers to a fixed error that cannot be corrected by two-point calibration of the detector under a certain operating condition. denoted as the nonlinear correction spectral responsivity; E is the integral of the original spectrum of the target being detected.

4. The nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation paths as described in claim 3, characterized in that, Based on the functional relationship between the radiation reaching the detector via a non-ideal path and the original spectrum of the target, and combined with the calculation formula for the nonlinear correction spectral responsivity, we obtain: in, , , These are nonlinear correction coefficients; make = * , = * , ,have to: When the detector's operating conditions change, while b1 and b2 remain unchanged, the error b0 under different operating conditions is corrected based on the calibrated blackbody spectral value to achieve correction of non-ideal path radiation.

5. The nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation paths as described in claim 1, characterized in that, During radiation calibration, acquiring the nonlinear interferometric data of the detector further includes: During the ground thermal vacuum radiation calibration before the probe is launched, various working conditions are simulated based on the on-orbit environment. Under each working condition, several cold blackbodies and one variable-temperature hot blackbodies are set. Multiple temperature points are set for the variable-temperature hot blackbodies to serve as the brightness temperature of the blackbodies. By rotating a two-dimensional scanning mirror to point at different temperature points, the detector response data is obtained.

6. The nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal radiation paths as described in claim 5, characterized in that, Multiple temperature points were set for the variable-temperature blackbody between 200.15K and 320.15K. When calibrating at two points, a high-temperature blackbody at 300.15K was used as the reference source. Based on the detector's response data, it was found that the nonlinearity of the detector system increases with the increase of the energy received by the detector. When the target blackbody temperature is lower than the reference source temperature, the actual response rate of the system is greater than the reference source response rate, and the calibrated brightness temperature is greater than the actual brightness temperature, resulting in a brightness temperature deviation greater than zero. When the target blackbody temperature is greater than the reference source temperature, the actual response rate of the system is less than the reference source response rate, and the calibrated brightness temperature is less than the actual brightness temperature, resulting in a brightness temperature deviation less than zero. Select a blackbody at 200.15K~320.15K under all working conditions, solve for 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 blackbody.

7. A nonlinear correction device for infrared hyperspectral remote sensing instruments emitting radiation via non-ideal paths, characterized in that, include: The nonlinear correction module is used to acquire the nonlinear interferometric data of the detector during radiometric calibration, and to perform preliminary correction on the original spectrum of the target based on the nonlinear response rate correction algorithm to obtain the nonlinear corrected spectral response rate. The two-point calibration module is used during on-orbit operation to construct a linear calibration model using a two-point calibration algorithm. Based on the linear calibration model, the spectral responsivity 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 reaching the detector via a non-ideal path and the original spectrum of the 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 target and the fixed error that cannot be corrected by two-point calibration, to obtain the non-ideal path radiation correction coefficient; the radiation reaching the detector via a non-ideal path includes the radiation from the target reaching the detector via a non-ideal path and the radiation from non-targets reaching the detector.

8. A nonlinear correction device for infrared hyperspectral remote sensing instruments emitting radiation via non-ideal pathways, characterized in that, include: A memory and at least one processor, wherein the memory stores instructions and the memory and the at least one processor are interconnected via a circuit; The at least one processor invokes the instructions in the memory to cause the nonlinear correction device for infrared hyperspectral remote sensing instruments with non-ideal path radiation to perform the nonlinear correction method for infrared hyperspectral remote sensing instruments with non-ideal path radiation as described in any one of claims 1-6.

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