A method and apparatus for evaluating stray light in orbit based on characteristic spectral lines of mercury lamps

Abstract

This invention discloses an on-orbit spectral stray light evaluation method and apparatus based on the characteristic spectral lines of mercury lamps. The method includes: acquiring interval combinations of the spectral stray light to be evaluated; calculating a first average value of a first count value of the onboard mercury lamps before satellite launch; wherein the count value is a numerical value quantified by the satellite to receive radiation; calculating a second average value of a second count value of the onboard mercury lamps after the satellite is in orbit; calculating a third average value, wherein the third average value is the difference between the second average value and the first average value; traversing the interval combinations of the spectral stray light to be evaluated, and evaluating the spectral stray light based on the third average value. This invention is based on common onboard mercury lamp observations and utilizes their characteristic spectral lines to conduct on-orbit spectral stray light evaluation, applicable to the solar reflection band. Compared with the traditional method of relying entirely on pre-launch measurement results, it helps to more realistically grasp the changes in the on-orbit response performance of remote sensors.

Description

Technical Field

[0001] This invention relates to the field of satellites, and in particular to an on-orbit spectral stray light evaluation method and apparatus based on the characteristic spectral lines of a mercury lamp. Background Technology

[0002] Spectral stray light refers to the percentage of light signal reaching the imaging surface from outside the operating wavelength band. It is caused by light scattering, optical element diffraction, and even instrument malfunction. Spectral stray light is generally classified into two types: Ghosts and Flare. Ghost stray light is caused by multiple reflections between imaging surfaces, while Flare stray light is caused by scattering within the optical system. Spectral stray light exists in detection systems across any wavelength band, introducing measurement errors, reducing the linearity of instrument response, and increasing over time. Therefore, spectral stray light detection needs to be performed frequently even after the remote sensor is in orbit.

[0003] In the laboratory, spectral stray light is typically measured using cutoff filters. Under external broadband illumination, narrowband filters are used to completely filter out specific wavelengths; the remaining response at that wavelength represents the contribution of stray light. Due to the lack of necessary equipment, the technology for on-orbit measurement of spectral stray light from remote sensors is currently nonexistent both domestically and internationally. Summary of the Invention

[0004] This invention provides an on-orbit spectral stray light evaluation method and device based on the characteristic spectral lines of a mercury lamp, which fills the technical gap in the existing on-orbit measurement remote sensor spectral stray light evaluation methods.

[0005] This invention discloses an on-orbit spectral stray light evaluation method based on characteristic spectral lines of a mercury lamp, the method comprising:

[0006] Obtain the interval combination of the stray light in the spectrum to be evaluated;

[0007] Calculate the first average of the first count values ​​of the onboard mercury lamps before satellite launch; where the count value is a numerical value quantified by the satellite to reflect the received radiation.

[0008] Calculate the second average of the second count values ​​of the onboard mercury lamps after the satellite is in orbit;

[0009] Calculate the third average value, which is the difference between the second average value and the first average value;

[0010] The interval combinations of the spectral stray light to be evaluated are traversed, and the spectral stray light is evaluated based on the third average value.

[0011] Optionally, traversing the interval combinations of the stray spectral light to be evaluated, and evaluating the stray spectral light based on the third average value includes:

[0012] The linear fit value of the third average value is calculated by sliding the slider through the spectral sampling points in the interval combination of the stray light to be evaluated.

[0013] The maximum observation noise is obtained. When the difference between the third average value and the linear fitting value is greater than twice the maximum observation noise, it is determined to be spectral stray light.

[0014] Optionally, obtaining the maximum observation noise includes: obtaining the variance of the second count value as the observation noise, wherein the maximum observation noise is the maximum value among the observation noises.

[0015] Optionally, obtaining the interval combination of stray light to be evaluated includes: removing the characteristic spectral lines of the mercury lamp.

[0016] Optionally, the method further includes: performing multiple iterations of the spectral sampling points in the interval combination of the stray spectral light to be evaluated, and deleting the spectral sampling point with the largest difference from the linear fitting value in each iteration.

[0017] Optionally, the size of the slider is greater than w×w b The first odd number; where w is the number of spectral sampling points, w b w is the slider coefficient. b The value range is from 0.001 to 0.1.

[0018] Optionally, the number of iterations is equal to b × w. n The closest integer; where the iteration coefficient w n The value range is from 0.1 to 0.4.

[0019] Optionally, the method includes: determining the evaluable minimum spectral stray according to the following formula. min ;

[0020]

[0021] Where λ contains the entire observed spectrum of the characteristic spectral lines of the mercury lamp, s(λ1) is the observation noise, and DN(λ) is the count value of the mercury lamp.

[0022] This invention discloses an on-orbit spectral stray light evaluation device based on characteristic spectral lines of a mercury lamp, the device comprising:

[0023] The first acquisition unit is used to acquire the interval combination of the stray light of the spectrum to be evaluated;

[0024] The first calculation unit is used to calculate the first average value of the first count value of the onboard mercury lamps before the satellite launch; wherein, the count value is a numerical value quantified by the satellite to measure the received radiation;

[0025] The second calculation unit is used to calculate the second average value of the second count value of the on-board mercury lamps after the satellite is in orbit;

[0026] The third calculation unit is used to calculate the third average value, which is the difference between the second average value and the first average value;

[0027] An evaluation unit is used to traverse the interval combinations of the spectral stray light to be evaluated and evaluate the spectral stray light based on the third average value.

[0028] The present invention provides a computer-readable storage medium storing one or more programs that can be executed by one or more processors to implement the steps of the on-orbit spectral stray light evaluation method based on the characteristic spectral lines of mercury lamps as described in any of the above claims.

[0029] The on-orbit spectral stray light evaluation method and device based on the characteristic spectral lines of mercury lamps in this invention evaluates on-orbit spectral stray light based on common on-board mercury lamp observations and utilizes their characteristic spectral lines. It is applicable to the solar reflection band and, compared with the traditional method of relying entirely on pre-launch measurement results, helps to more realistically grasp the changes in the on-orbit response performance of remote sensors. Attached Figure Description

[0030] Figure 1 This is a flowchart of an on-orbit spectral stray light evaluation method based on the characteristic spectral lines of a mercury lamp, as described in an embodiment of the present invention.

[0031] Figure 2 This is a structural diagram of an on-orbit spectral stray light evaluation device based on the characteristic spectral lines of a mercury lamp, as described in an embodiment of the present invention.

[0032] Figures 3A-3D This is a schematic diagram of spectral stray light analysis of the ultraviolet hyperspectral ozone detector - limb OMS-L band 1 in an embodiment of the present invention;

[0033] Figures 4A-4D This is a schematic diagram of spectral stray light analysis of the ultraviolet hyperspectral ozone detector - limb OMS-L band 2 in an embodiment of the present invention. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0035] This invention provides a method for evaluating on-orbit stray light based on the characteristic spectral lines of a mercury lamp, such as... Figure 1 As shown, the method includes:

[0036] Step 100: Obtain the interval combination of the stray light to be evaluated. In a specific embodiment, the spectrum of the stray light to be evaluated is not continuous, but consists of multiple intervals. Therefore, the stray light to be evaluated obtained in step 100 is a combination of multiple intervals and is denoted as λ1. In the subsequent calculation process, the interval combination λ1 of the stray light to be evaluated is treated as a whole for calculation.

[0037] Step 200: Calculate the first average value of the first count value of the onboard mercury lamps before satellite launch; wherein, the count value is a value quantified by the satellite to measure the received radiation. Step 200 is usually calculated before satellite launch, that is, by observing the onboard mercury lamps equipped with remote sensors, calculating the first count value DN0(λ1) and the first average value m0(λ1) of the first count value DN0(λ1).

[0038] Step 300: Calculate the second average value of the second count value of the onboard mercury lamp after the satellite is in orbit. Step 300 involves observing the onboard mercury lamp mounted on the remote sensor after the satellite is launched and enters orbit, calculating the second count value DN(λ1), and the second average value m(λ1) of the second count value DN(λ1).

[0039] Step 400: Calculate the third average value, which is the difference between the second average value and the first average value. In this step, the difference between the second average value obtained in steps 200 and 300 and the first average value is calculated, i.e., m(λ1)-m0(λ1), to obtain the third average value.

[0040] Step 500: Traverse the interval combinations of the spectral stray light to be evaluated, and evaluate the spectral stray light based on the third average value. The spectral stray light can be evaluated by traversing the interval combinations of the spectral stray light to be evaluated based on the third average value.

[0041] In specific embodiments, the method described in this embodiment is band selective and can only be used to evaluate the level of spectral stray light brought about by the characteristic spectral lines of the mercury lamp outside its normal response band. It cannot evaluate whether the characteristic spectral lines of the mercury lamp bring about spectral stray light within its normal response band because these spectral stray lights overlap with the signal of the characteristic spectral lines and cannot be separated; it also cannot evaluate the contribution of bands without the characteristic spectral lines of the mercury lamp to the spectral stray light because the mercury lamp has no energy output in these bands.

[0042] The on-orbit spectral stray light evaluation method based on the characteristic spectral lines of mercury lamps described in the above embodiments of the present invention can directly observe the pre-launch count value and on-orbit count value of the satellite through the on-board mercury lamp, and conduct on-orbit spectral stray light evaluation using the characteristic spectral lines of the mercury lamp. It is applicable to the solar reflection band and, compared with the traditional method of relying entirely on pre-launch measurement results, can more realistically grasp the changes in the on-orbit response performance of remote sensors.

[0043] In a preferred embodiment of the present invention, traversing the interval combinations of the stray spectral light to be evaluated, and evaluating the stray spectral light based on the third average value includes:

[0044] The linear fit value of the third average is calculated by sliding a slider through the spectral sampling points in the interval combination of the stray light to be evaluated, point by point. Specifically, the linear fit value m(λ1)-m0(λ1) is calculated by sliding a slider of size b through each spectral sampling point in λ1. p (λ1). The number of spectral sampling points depends on the detector specifications.

[0045] The maximum observation noise is obtained. When the difference between the third average value and the linear fitting value is greater than twice the maximum observation noise, it is determined to be spectral stray light.

[0046] Specifically, when the difference between the second average of the second count value before and after emission and the first average of the first count value is greater than twice the noise, it is determined to be spectral stray light. The specific formula is as follows: (m(λ1)-m0(λ1))-m p (λ1)>2×max(s(λ1)). Where s(λ1) is the observation noise and max(s(λ1)) is the maximum observation noise.

[0047] In a preferred embodiment of the present invention, obtaining the maximum observation noise includes: obtaining the variance s(λ1) of the second count value DN(λ1) as the observation noise, that is, the observation noise is also s(λ1), and the maximum observation noise max(s(λ1)) is the maximum value in the observation noise s(λ1).

[0048] In a preferred embodiment of the present invention, obtaining the interval combination of stray light to be evaluated includes: removing the characteristic spectral lines of the mercury lamp. Specifically, in a concrete embodiment, the characteristic spectral lines of the mercury lamp can be removed through manual identification.

[0049] In a preferred embodiment of the present invention, the method further includes: performing multiple iterations of traversing the spectral sampling points in the interval combination of the stray spectral light to be evaluated, and deleting the spectral sampling point with the largest difference from the linear fitting value in each traversal. Specifically, step 500 in the specific embodiment of the present invention is iterated multiple times. Let the number of iterations be n, then each spectral sampling point in λ1 is traversed by a slider of size b, and the linear fitting value m of m(λ1)-m0(λ1) is calculated by sliding the slider point by point. p (λ1). After deleting the spectral sampling point with the largest difference from the linear fitting value in each iteration, the next iteration begins. Therefore, the slider size b decreases by 1 with each iteration.

[0050] In a preferred embodiment of the present invention, the size b of the slider is greater than w × w b The first odd number; where w is the number of spectral sampling points, w b This is the slider coefficient. In a specific embodiment, for a set of spectral sampling points with a count value of w, the slider size b is greater than and closest to w × w. b An odd number is used to ensure that the same number of spectral sampling points are taken on both sides of the center of the slider. Where the slider coefficient w b The value range is from 0.001 to 0.1, w b The larger the slider, the larger it becomes.

[0051] In a preferred embodiment, the number of spectral sampling points at the center of the slider will be less than 1 at both ends of λ1. In this case, the number of spectral sampling points used in the iteration is equal to the number of spectral sampling points available.

[0052] In a preferred embodiment of the present invention, the number of iterations is equal to b × w. n The closest integer; where the iteration coefficient w n The value range is from 0.1 to 0.4. Where, w n The larger the value, the more iterations are required.

[0053] In a preferred embodiment of the present invention, the method includes: determining the minimum evaluable spectral stray according to the following formula. min ;

[0054]

[0055] Where λ is the entire observed spectrum of the characteristic spectral lines of the mercury lamp, s(λ1) is the observation noise, and DN(λ) is the count value of the mercury lamp.

[0056] A specific embodiment of the present invention also provides an on-orbit spectral stray light evaluation device based on the characteristic spectral lines of a mercury lamp, such as... Figure 2 As shown, the device includes:

[0057] The first acquisition unit 201 is used to acquire the interval combination of the spectral stray light to be evaluated;

[0058] The first calculation unit 202 is used to calculate the first average value of the first count value of the onboard mercury lamps before the satellite launch; wherein, the count value is a value quantified by the satellite to measure the received radiation;

[0059] The second calculation unit 203 is used to calculate the second average value of the second count value of the on-board mercury lamp after the satellite is in orbit;

[0060] The third calculation unit 204 is used to calculate the third average value, which is the difference between the second average value and the first average value;

[0061] Evaluation unit 205 is used to traverse the interval combinations of the spectral stray light to be evaluated and evaluate the spectral stray light based on the third average value.

[0062] The following is an example of applying this method to evaluate the spectral stray light of the OMS-L (Oultraviolet Hyperspectral Ozone Detector-Liminary) remote sensor on the Fengyun-3F satellite (successfully launched on August 3, 2023). Both OMS-L bands 1 and 2 have w = 2000 spectral sampling points. Taking w... b =0.05, w n =0.2, corresponding to b=101, n=51. The positions of the characteristic spectral lines of the mercury lamp corresponding to bands 1 and 2 are shown in Tables 1 and 2. In addition, the mercury lamp generates a mercury spectrum by igniting with argon gas, and a weak argon spectrum can be observed in band 2, as shown in Table 3.

[0063] Table 1. Selection of characteristic spectral lines for mercury lamps in band 1.

[0064]

[0065]

[0066] Table 2 Selection of characteristic spectral lines for mercury lamps in band 2

[0067] 404.77081 404.65650 12000 407.89883 407.78370 1000 434.04431 433.92232 50 434.87166 434.74945 150 435.95600 435.83350 12000 491.7440 491.6068 20

[0068] Table 3 Selection of Argon Characteristic Spectral Lines in Band 2

[0069] 415.9763 415.8590 400 420.1858 420.0674 400

[0070] Analysis results as follows Figures 3A-3D As shown in 4A-4D.

[0071] Figures 3A-3D Spectral stray light analysis for OMS-L band 1. Specifically, Figure 3A The average of the count values ​​DN of the mercury lamps before satellite launch and the simulated on-orbit count values. Figure 3B To simulate the difference between the average count value DN of the mercury lamps in orbit and before launch; Figure 3C To simulate the variance of the on-orbit mercury lamp count value DN, as observation noise; Figure 3D The difference between the mercury lamp counts before and after emission and the fitted value is represented by the upper and lower black lines, which indicate a noise factor of 2. Discrete points outside these lines indicate the presence of spectral stray light. In this specific embodiment, the minimum detectable stray light in band 1 is *stray*. min =1.49*10 -3 No stray light exceeding this threshold was detected.

[0072] Figures 4A-4D The analysis of stray light in band 2 is similar to that in band 1 and will not be repeated here. Specifically, the minimum detectable stray light in band 2 is... min =3.21*10 -4 No stray spectral light exceeding this threshold was detected. For OMS-L, this method can be used to evaluate whether the on-orbit stray spectral light of the remote sensor exceeds the error of the evaluation method within the applicable bands. In this example, neither band 1 nor band 2 detected stray light exceeding the minimum detectable value (1.49*10). -3 3.21*10 -4 ) spectral stray light.

[0073] It should be understood that in the various embodiments of this document, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this document.

[0074] This invention also provides a computer-readable storage medium storing one or more programs that can be executed by one or more processors to implement the steps of the on-orbit spectral stray light evaluation method based on mercury lamp characteristic spectral lines as described in any of the above specific embodiments.

[0075] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0076] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0077] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0078] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0079] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for evaluating stray light in orbit based on characteristic spectral lines of a mercury lamp, characterized in that, The method includes: Obtaining the interval combination of stray light in the spectrum to be evaluated includes: removing the characteristic spectral lines of the mercury lamp; For the interval combination of the stray light in the spectrum to be evaluated, calculate the first average value of the first count value of the onboard mercury lamp before the satellite launch; wherein, the first count value is the value of the satellite quantifying the received radiation; For the interval combination of the stray light in the spectrum to be evaluated, calculate the second average value of the second count value of the onboard mercury lamp after the satellite is in orbit. The second count value is a value quantified by the satellite for the received radiation. Calculate the third average value, which is the difference between the second average value and the first average value; The interval combinations of the spectral stray light to be evaluated are traversed, and the spectral stray light is evaluated based on the third average value; The evaluation of spectral stray light based on the third average value, which involves traversing the interval combinations of the stray light to be evaluated, includes: The linear fit value of the third average value is calculated by sliding the slider through the spectral sampling points in the interval combination of the stray light to be evaluated. The maximum observation noise is obtained. When the difference between the third average value and the linear fitting value is greater than twice the maximum observation noise, it is determined to be spectral stray light. The process of obtaining the maximum observation noise includes obtaining the variance of the second count value as the observation noise, wherein the maximum observation noise is the maximum value among the observation noises.

2. The on-orbit spectral stray light evaluation method based on the characteristic spectral lines of a mercury lamp according to claim 1, characterized in that, The method further includes: performing multiple iterations of the spectral sampling points in the interval combination of the stray light to be evaluated, and deleting the spectral sampling point with the largest difference from the linear fitting value in each iteration.

3. The on-orbit spectral stray light evaluation method based on the characteristic spectral lines of a mercury lamp according to claim 1, characterized in that, The size of the slider is greater than w. The first odd number; where w is the number of spectral sampling points, The slider coefficient, The value range is from 0.001 to 0.

1.

4. The on-orbit spectral stray light evaluation method based on the characteristic spectral lines of a mercury lamp according to claim 2, characterized in that, The number of iterations is equal to the number of iterations. The closest integer; where the iteration coefficients are... The value of is in the range of 0.1 to 0.4; b is the size of the slider.

5. The on-orbit spectral stray light evaluation method based on the characteristic spectral lines of a mercury lamp according to claim 1, characterized in that, The method includes: determining the minimum evaluable spectral stray light according to the following formula. ; ， in, To evaluate the combination of spectral stray light regions after removing the characteristic spectral lines of the mercury lamp, The entire observed spectrum, including the characteristic spectral lines of the mercury lamp. To observe the noise, This refers to the count value of the onboard mercury lamps after the satellite is in orbit.

6. An on-orbit spectral stray light evaluation device based on the characteristic spectral lines of a mercury lamp, characterized in that, The device includes: The first acquisition unit is used to acquire the interval combination of the spectral stray light to be evaluated, which includes: removing the characteristic spectral lines of the mercury lamp; The first calculation unit is used to calculate the first average value of the first count value of the onboard mercury lamp before the satellite launch for the interval combination of the stray light of the spectrum to be evaluated; wherein, the first count value is a value quantified by the satellite for the received radiation; The second calculation unit is used to calculate the second average value of the second count value of the onboard mercury lamp after the satellite is in orbit, for the interval combination of the stray light of the spectrum to be evaluated. The second count value is a value quantified by the satellite for the received radiation. The third calculation unit is used to calculate the third average value, which is the difference between the second average value and the first average value; An evaluation unit, used to traverse the interval combinations of the stray spectral light to be evaluated, and evaluate the stray spectral light based on the third average value, includes: The linear fit value of the third average value is calculated by sliding the slider through the spectral sampling points in the interval combination of the stray light to be evaluated. The maximum observation noise is obtained. When the difference between the third average value and the linear fitting value is greater than twice the maximum observation noise, it is determined to be spectral stray light. The process of obtaining the maximum observation noise includes obtaining the variance of the second count value as the observation noise, wherein the maximum observation noise is the maximum value among the observation noises.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores one or more programs, which can be executed by one or more processors to implement the steps of the on-orbit spectral stray light evaluation method based on the characteristic spectral lines of a mercury lamp as described in any one of claims 1 to 5.

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