FTIR optical axis and pixel off-axis angle correction method and device, equipment and storage medium
By obtaining the reference spectrum line and spectral deviation calculation of FTIR, the optical axis position of FTIR is quickly corrected, and the problem of optical axis offset in space environment is solved, and the near-real-time high-precision detection of FTIR is achieved.
Patent Information
- Application Number
- CN202510464681.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-14
- Publication Date
- 2025-07-11
AI Technical Summary
The existing FTIR optical axis offset correction method cannot respond to the dynamic changes of the optical axis in real time, making it difficult to ensure high-precision detection in orbit, especially under the influence of temperature changes and vibration in space environments, it is difficult to quickly correct the optical axis offset problem.
By obtaining multiple reference spectral lines and their theoretical wave numbers, Fourier transform and spectral deviation calculations are performed, and surface fitting or optimization problems are constructed based on the correspondence between spectral deviation and optical axis position, and the optical axis position of FTIR is quickly corrected.
It realizes rapid optical axis position correction based on dynamic changes in optical axis in near real time, and improves the high-precision detection capability of FTIR in orbit.
Smart Images
Figure CN120293893A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field of infrared Fourier spectrometers, and particularly to a method, apparatus, device, and storage medium for correcting the optical axis and pixel off-axis angle of an FTIR. Background Art
[0002] In the context of the booming development of current space technology, FTIR (Fourier Transform infrared spectroscopy) occupies an indispensable position in many on-orbit scientific exploration, environmental monitoring, and space target recognition tasks by virtue of its advantage of being able to perform high-precision infrared spectral detection on target objects.
[0003] However, the space environment is extremely complex and harsh, which brings many challenges to the infrared Fourier spectrometer operating in orbit. Among them, the problem of optical axis deviation is particularly prominent. On the one hand, temperature changes are inevitable in space. From the sunny side to the shady side, the instrument has to experience temperature changes. Such temperature changes will cause thermal expansion and contraction of the optical elements, mechanical structures, etc. inside the spectrometer, thereby changing the relative positions and angles between the components and resulting in the deviation of the optical axis. For example, the barrel structure may undergo slight deformation due to thermal expansion and contraction, causing the optical path to no longer be in the ideal state of the original design, and the optical axis will deviate accordingly. On the other hand, vibration is also a factor that cannot be ignored. During the launch stage and in-orbit operation of a spacecraft, it will be affected by vibrations generated by factors such as engine ignition, attitude adjustment, and the deployment and rotation of solar wings. These vibrations are transmitted to the infrared Fourier spectrometer, causing small displacements of the optical components inside the instrument and resulting in the deviation of the optical axis. In addition, factors such as radiation and particle impact in the space environment will also have a certain impact on the material properties and structural stability of the instrument, indirectly promoting the occurrence of optical axis deviation, thereby causing changes in the off-axis angles of the detectors on the area array.
[0004] Regarding the problem of optical axis offset, there are currently two main correction methods. One is to rely on reanalysis meteorological data (such as ERA5, etc.) to drive an atmospheric radiative transfer model (such as LBLRTM, etc.) to obtain the true spectrum, compare it with the observed spectrum, analyze the spectral offset in a specific band, and then correct the optical axis drift. The other is to use the cross-calibration method, using the observations of polar-orbiting satellites with high internationally recognized accuracy as the true spectrum. After spatial, temporal, spectral, and angular matching, it is used for optical axis drift correction. For the former of these two methods, the timeliness of the reanalysis meteorological data it relies on is too low (usually lagging by 1 - 2 days), while for the latter, there is too little polar-orbiting satellite observation data that meets the spatio-temporal matching requirements (usually only 1 - 2 observations per day can meet the criteria). Therefore, the existing optical axis drift correction methods cannot respond quickly in real time according to the dynamic changes of the optical axis. In some mission scenarios that require continuous high-precision detection, it is difficult to ensure that the spectrometer is always in the best working state and cannot well meet the strict requirements of on-orbit high-precision detection. Summary of the Invention
[0005] To solve the problems in the related art, embodiments of the present disclosure provide a method, apparatus, device, and storage medium for correcting the optical axis and pixel off-axis angle of an FTIR.
[0006] In a first aspect, embodiments of the present disclosure provide an optical axis correction method for an FTIR, including:
[0007] Obtain multiple reference spectral lines and their corresponding theoretical wave numbers, where the reference spectral lines include the spectral lines of predetermined atmospheric molecules within the observation spectral range of an infrared Fourier transform spectrometer (FTIR);
[0008] Perform Fourier transform on the interference data of each pixel to obtain the observed spectrum of each pixel, where the observed spectrum is the radiation digital quantization (DN) value corresponding to different wave numbers;
[0009] For each reference spectral line, based on the observed spectrum of each pixel, obtain the radiation DN value within the target wave number range in the observed spectrum of each pixel, obtain the wave number corresponding to the maximum radiation DN value within the radiation DN values within the target wave number range, and use the difference between the wave number corresponding to the maximum radiation DN value and the theoretical wave number as the spectral deviation of each pixel; the target wave number range is the range that is a predetermined wave number away from the theoretical wave number of the reference spectral line;
[0010] Based on the correspondence between the spectral deviation of each pixel and the correct optical axis position, obtain the corrected optical axis position according to the spectral deviation of each pixel;
[0011] Based on the corrected optical axis positions corresponding to each reference spectral line, obtain the finally corrected optical axis position.
[0012] In a possible implementation, obtaining the reference spectral line and its corresponding theoretical wavenumber includes:
[0013] Based on the line-by-line radiative transfer model LBLRTM, calculate the high-resolution spectral line information of relevant atmospheric molecules within the FTIR observation spectral range under standard atmospheric conditions;
[0014] Based on the high-resolution spectral line information, select the spectral lines of CO2 and H2O molecules among the relevant atmospheric molecules in the infrared long-wave band as the reference spectral lines;
[0015] Based on the spectral line information of atmospheric molecules recorded in the high-resolution transmission molecular absorption database HITRAN, obtain the theoretical wavenumber corresponding to the reference spectral line.
[0016] In a possible implementation, based on the correspondence between the spectral deviation of each pixel and the correct optical axis position, obtaining the corrected optical axis position according to the spectral deviation of each pixel includes:
[0017] Perform surface fitting based on the spectral deviation of each pixel to obtain the fitted surface function;
[0018] Based on the surface function, calculate the position of the pixel when the spectral deviation is the smallest as the corrected optical axis position.
[0019] In a possible implementation, based on the correspondence between the spectral deviation of each pixel and the correct optical axis position, obtaining the corrected optical axis position according to the spectral deviation of each pixel includes:
[0020] Construct an optimization problem, where the decision variable of the optimization problem is the position of the pixel, the objective function is to minimize the spectral deviation, and the constraint condition is that the position of the pixel is within the pixel position range of the FTIR;
[0021] Based on the spectral deviation of each pixel, solve the optimization problem to obtain the position of the pixel when the spectral deviation is the smallest as the corrected optical axis position.
[0022] In a possible implementation, based on the corrected optical axis positions corresponding to each reference spectral line, obtaining the finally corrected optical axis position includes:
[0023] Perform arithmetic averaging on the corrected optical axis positions corresponding to each reference spectral line to obtain the finally corrected optical axis position.
[0024] In a second aspect, an embodiment of the present disclosure provides a method for correcting the off-axis angle of pixels of an FTIR, including:
[0025] Obtain the finally corrected optical axis position according to the method described in any item of the first aspect;
[0026] Based on the finally corrected optical axis position, obtain the off-axis angle correction value for each pixel.
[0027] In a third aspect, an embodiment of the present disclosure provides an optical axis correction device for FTIR, including:
[0028] A reference spectrum acquisition module, configured to acquire multiple reference spectra and their corresponding theoretical wave numbers, where the reference spectra include spectra of predetermined atmospheric molecules within the observation spectral range of the Fourier transform infrared spectrometer (FTIR);
[0029] An observation spectrum acquisition module, configured to perform Fourier transform on the interference data of each pixel respectively to obtain the observation spectrum of each pixel, where the observation spectrum is the radiation digital quantization (DN) value corresponding to different wave numbers;
[0030] A spectrum deviation acquisition module, configured to, for each reference spectrum, based on the observation spectrum of each pixel, acquire the radiation DN value within the target wave number range in the observation spectrum of each pixel, obtain the wave number corresponding to the maximum radiation DN value among the radiation DN values within the target wave number range, and use the difference between the wave number corresponding to the maximum radiation DN value and the theoretical wave number as the spectrum deviation of each pixel; the target wave number range is a range that is a predetermined wave number away from the theoretical wave number of the reference spectrum;
[0031] An optical axis correction module, configured to obtain the corrected optical axis position according to the spectrum deviation of each pixel based on the correspondence between the spectrum deviation of each pixel and the correct optical axis position; and obtain the finally corrected optical axis position based on the corrected optical axis positions corresponding to each reference spectrum.
[0032] In a fourth aspect, an embodiment of the present disclosure provides a pixel off-axis angle correction device for FTIR, including:
[0033] An optical axis correction module, configured to obtain the finally corrected optical axis position according to the method described in any item of the first aspect;
[0034] An off-axis angle correction module, configured to obtain the off-axis angle correction value for each pixel based on the finally corrected optical axis position.
[0035] In a fifth aspect, an embodiment of the present disclosure provides an electronic device, including a memory and a processor, where the memory is used to store one or more computer instructions, and the one or more computer instructions are executed by the processor to implement the method described in any item of the first aspect or the second aspect.
[0036] In a sixth aspect, an embodiment of the present disclosure provides a computer-readable storage medium, on which computer instructions are stored. When the computer instructions are executed by a processor, the method described in any one of the first aspect or the second aspect is implemented.
[0037] According to the technical solution provided by the embodiment of the present disclosure, multiple reference spectral lines and their corresponding theoretical wave numbers can be obtained. The reference spectral lines include the spectral lines of predetermined atmospheric molecules within the observation spectral range of an infrared Fourier transform spectrometer (FTIR); the interference data of each pixel is respectively subjected to Fourier transform to obtain the observation spectrum of each pixel, and the observation spectrum is the radiation digital quantization (DN) value corresponding to different wave numbers; for each reference spectral line, based on the observation spectrum of each pixel, the radiation DN value within the target wave number range in the observation spectrum of each pixel is obtained, the wave number corresponding to the maximum radiation DN value in the radiation DN values within the target wave number range is obtained, and the difference between the wave number corresponding to the maximum radiation DN value and the theoretical wave number is used as the spectral deviation of each pixel; the target wave number range is a range that is separated from the theoretical wave number of the reference spectral line by a predetermined wave number; based on the correspondence between the spectral deviation of each pixel and the correct optical axis position, the corrected optical axis position is obtained according to the spectral deviation of each pixel; based on the corrected optical axis positions corresponding to each reference spectral line, the finally corrected optical axis position is obtained. The correction of the above optical axis position only needs to rely on the observation spectrum of the FTIR, and the observation spectrum of the FTIR can be obtained quickly near real-time. Therefore, the optical axis position can be corrected quickly according to the dynamic change of the optical axis near real-time.
[0038] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] In combination with the drawings, through the following detailed description of non-limiting embodiments, other features, objects, and advantages of the present disclosure will become more obvious. In the drawings:
[0040] Figure 1 A flowchart showing a method for correcting the optical axis of an FTIR provided by an embodiment of the present disclosure is shown.
[0041] Figure 2 A schematic diagram of a two-dimensional rectangular coordinate system of a detector array provided by this embodiment is shown.
[0042] Figure 3 A flowchart showing a method for correcting the off-axis angle of pixels of an FTIR provided by an embodiment of the present disclosure is shown.
[0043] Figure 4 A two-dimensional matrix diagram of each pixel and the spectral deviation before and after the off-axis angle correction is shown.
[0044] Figure 5The structural block diagram of an optical axis correction device for an FTIR provided by an embodiment of the present disclosure is shown.
[0045] Figure 6 The structural block diagram of a pixel off-axis angle correction device for an FTIR provided by an embodiment of the present disclosure is shown.
[0046] Figure 7 The structural block diagram of an electronic device according to an embodiment of the present disclosure is shown.
[0047] Figure 8 The structural schematic diagram of a computer system suitable for implementing the method of an embodiment of the present disclosure is shown. Detailed implementation manners
[0048] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. In addition, for the sake of clarity, parts irrelevant to the description of the exemplary embodiments are omitted in the drawings.
[0049] In the present disclosure, it should be understood that terms such as "including" or "having" are intended to indicate the presence of features, numbers, steps, actions, components, parts, or combinations thereof disclosed in this specification, and are not intended to exclude the possibility of the presence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.
[0050] In addition, it should be noted that, without conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.
[0051] Figure 1 The flowchart of an optical axis correction method for an FTIR provided by an embodiment of the present disclosure is shown.
[0052] As Figure 1 shown, the optical axis correction method for the FTIR includes the following steps S101 - S105:
[0053] In step S101, a plurality of reference spectral lines and their corresponding theoretical wave numbers are obtained, and the reference spectral lines include spectral lines of predetermined atmospheric molecules within the observation spectral range of the infrared Fourier spectrometer FTIR;
[0054] In step S102, Fourier transform is respectively performed on the interference data of each pixel to obtain the observation spectrum of each pixel, and the observation spectrum is the radiation digital quantization DN value corresponding to different wave numbers;
[0055] In step S103, for each reference spectral line, based on the observed spectrum of each pixel, obtain the radiation DN value within the target wavenumber range in the observed spectrum of each pixel, obtain the wavenumber corresponding to the maximum radiation DN value among the radiation DN values within the target wavenumber range, and use the difference between the wavenumber corresponding to the maximum radiation DN value and the theoretical wavenumber as the spectral deviation of each pixel; the target wavenumber range is the range that is a predetermined wavenumber away from the theoretical wavenumber of the reference spectral line;
[0056] In step S104, based on the correspondence between the spectral deviation of each pixel and the correct optical axis position, obtain the corrected optical axis position according to the spectral deviation of each pixel;
[0057] In step S105, based on the corrected optical axis positions corresponding to each reference spectral line, obtain the finally corrected optical axis position.
[0058] In a possible implementation, the optical axis correction of this FTIR is applicable to electronic devices such as computing devices and servers that can perform the calculation of the optical axis correction of the FTIR.
[0059] In a possible implementation, the reference spectral line is the spectral line of a predetermined atmospheric molecule within the FTIR observation spectral range. The FTIR observation spectral range can be the infrared band, such as the long-wave infrared band. The predetermined atmospheric molecule is usually a common molecule in the atmosphere, such as CO2 and H2O molecules. Usually, the reference spectral line needs to be a well-isolated (i.e., not affected by other gas molecules) spectral line.
[0060] In a possible implementation, the spectral line information of atmospheric molecules can be downloaded from the online database of HITRAN (HIgh-resolution TRANsmission molecular absorption database). The theoretical wavenumber of each spectral line is recorded in the spectral line information, so that the theoretical wavenumber corresponding to the reference spectral line can be obtained. The theoretical wavenumber refers to the wavenumber of the spectral line calculated according to quantum mechanics and spectroscopy theories.
[0061] In a possible implementation, the interference data of each pixel in the FTIR can be obtained by precisely controlling the optical path difference, triggering the acquisition using a reference laser, and recording the light intensity change by the detector of the FTIR. The Fourier transform is performed on the interference data of each pixel respectively to obtain the observed spectrum of each pixel. The observed spectrum is the radiation DN (Digital Number) value corresponding to different wavenumbers, and the radiation quantization value can be the quantization result of the radiation intensity.
[0062] In a possible implementation, for a certain reference spectral line, the theoretical wavenumber of the reference spectral line is σT , we can obtain the observed spectrum of each pixel corresponding to this σ T The radiation DN values with a predetermined wavenumber interval between them are obtained, and the wavenumber corresponding to the maximum radiation DN value among these radiation DN values is determined. The difference between the wavenumber corresponding to the maximum radiation DN value and the theoretical wavenumber is taken as the spectral deviation of each pixel. In this way, the spectral deviation of all pixels of the FTIR can be obtained for each reference spectrum line.
[0063] In a possible implementation, a two-dimensional rectangular coordinate system of the FTIR detector array can be defined: Assuming that the detector array has a total of M×N pixels, arranged in the form of M rows and N columns, Figure 2 A schematic diagram of a two-dimensional rectangular coordinate system of a detector array provided in this embodiment is shown, Figure 2 As shown, the lower left corner of the detector array can be taken as the origin, the vertical intersection of the optical axis and the detector array is at the center of the detector array, that is, the origin of the optical axis, and the coordinates are marked as (x0, y0). The coordinates of a detector on the detector array are marked as (x, y), and its off-axis angle θ (x，y) for:
[0064] Where f is the focal length.
[0065] From the off-axis angle calculation formula, we know that the farther the pixel is from the optical axis, the larger the off-axis angle θ is. T The reference spectral line, whose corresponding wave number in the detector spectrum of the theoretical optical axis (x0, y0) is Right now Due to the influence of the off-axis angle, the corresponding wave number in the pixel (x, y) spectrum is From this formula, we can see that the larger the off-axis angle, the greater the theoretical wave number of the reference spectrum line and the wave number σ (x，y) The greater the difference between them, the greater the spectral deviation.
[0066] From the above, it can be seen that the farther the pixel is from the correct optical axis position, the greater the spectral deviation. This is the correspondence between the spectral deviation of each pixel and the correct optical axis position. Based on this correspondence, the spectral deviation of each pixel under the reference spectrum line calculated above can be calculated to obtain the corrected optical axis position.
[0067] It should be noted here that Figure 2 The rectangular coordinate system shown is only an example, and other rectangular coordinate systems can also be defined, which are not listed here one by one.
[0068] In a possible implementation, a corrected optical axis position corresponding to each reference spectral line can be calculated according to the above steps. Based on the corrected optical axis positions corresponding to these reference spectral lines, the finally corrected optical axis position can be obtained. For example, a mathematical average calculation can be performed on the corrected optical axis positions corresponding to each reference spectral line to obtain the finally corrected optical axis position, or a weighted average calculation can be performed on the corrected optical axis positions corresponding to each reference spectral line (the better the reference spectral line, the higher the weight) to obtain the finally corrected optical axis position.
[0069] In this implementation, multiple reference spectral lines and their corresponding theoretical wavenumbers can be obtained. The reference spectral lines include the spectral lines of predetermined atmospheric molecules within the FTIR observation spectral range of the infrared Fourier spectrometer. Fourier transform is respectively performed on the interference data of each pixel to obtain the observed spectrum of each pixel. The observed spectrum is the radiation digital quantization (DN) value corresponding to different wavenumbers. For each reference spectral line, based on the observed spectrum of each pixel, the radiation DN value within the target wavenumber range in the observed spectrum of each pixel is obtained, and the wavenumber corresponding to the maximum radiation DN value within the radiation DN values within the target wavenumber range is obtained. The difference between the wavenumber corresponding to the maximum radiation DN value and the theoretical wavenumber is used as the spectral deviation of each pixel. The target wavenumber range is the range that is separated from the theoretical wavenumber of the reference spectral line by a predetermined wavenumber. Based on the correspondence between the spectral deviation of each pixel and the correct optical axis position, the corrected optical axis position is obtained according to the spectral deviation of each pixel. Based on the corrected optical axis positions corresponding to each reference spectral line, the finally corrected optical axis position is obtained. The correction of the above optical axis position only relies on the observed spectrum of the FTIR, and the observed spectrum of the FTIR can be obtained quickly near real-time. Therefore, the optical axis position can be corrected quickly according to the dynamic change of the optical axis near real-time.
[0070] In a possible implementation, the obtaining of the reference spectral line and its corresponding theoretical wavenumber includes:
[0071] Based on the line-by-line radiative transfer model (LBLRTM), calculate the high-resolution spectral line information of relevant atmospheric molecules within the FTIR observation spectral range under standard atmospheric conditions;
[0072] Based on the high-resolution spectral line information, select the spectral lines of CO2 and H2O molecules in the infrared long-wave band among the relevant atmospheric molecules as reference spectral lines;
[0073] Based on the spectral line information of atmospheric molecules recorded in the high-resolution transmission molecular absorption database (HITRAN), obtain the theoretical wavenumber corresponding to the reference spectral line.
[0074] In this embodiment, the LBLRTM (Line-By-Line Radiative Transfer Model) is a high-precision radiative transfer model based on the HITRAN database. It can calculate the gas absorption and emission spectra line by line and accurately simulate the radiation transfer process in the atmosphere. Therefore, based on this LBLRTM, the high-resolution spectral line information of each atmospheric molecule within the FTIR observation spectral range under standard atmospheric conditions can be calculated. Among them, the relevant atmospheric molecules include all gases supported by the LBLRTM, and the spectral line information is the atmospheric transmittance and wavenumber at the top of the atmosphere.
[0075] In this embodiment, for the high-resolution spectral line information of CO2 and H2O molecules, in the long-wave infrared band, several well-isolated (not affected by other gas molecules) spectral lines can be selected as reference spectral lines; and based on the spectral line information of atmospheric molecules recorded in HITRAN, the theoretical wavenumber corresponding to the reference spectral lines can be obtained.
[0076] In a possible embodiment, the obtaining of the corrected optical axis position according to the spectral deviation of each pixel based on the correspondence between the spectral deviation of each pixel and the correct optical axis position includes:
[0077] Performing surface fitting based on the spectral deviation of each pixel to obtain a fitted surface function;
[0078] Based on the surface function, calculating the position of the pixel with the smallest spectral deviation as the corrected optical axis position.
[0079] In this embodiment, surface fitting is a mathematical technique used to find a surface function according to a set of data points, and this surface function can approximately represent the distribution of the data; its purpose is to construct a function surface that fits a set of discrete data points as perfectly as possible. In this embodiment, the discrete data points are the spectral deviations of each pixel.
[0080] In this embodiment, as described above, the farther the pixel is from the correct optical axis position, the greater the spectral deviation. On the contrary, the closer the pixel is to the correct optical axis position, the smaller the spectral deviation. Therefore, based on the surface function, the position of the pixel with the smallest spectral deviation can be calculated as the corrected optical axis position.
[0081] In a possible embodiment, the obtaining of the corrected optical axis position according to the spectral deviation of each pixel based on the correspondence between the spectral deviation of each pixel and the correct optical axis position includes:
[0082] Construct an optimization problem, where the decision variable of the optimization problem is the position of the pixel, the objective function is to minimize the spectral deviation, and the constraint condition is that the position of the pixel is within the pixel position range of the FTIR;
[0083] Based on the spectral deviation of each pixel, solve the optimization problem, and obtain that the position of the pixel when the spectral deviation is minimized is the corrected optical axis position.
[0084] In this embodiment, an optimization problem refers to finding a value of a decision variable under given constraint conditions such that the objective function reaches a minimum or maximum value. In this embodiment, the decision variable of this optimization problem is the position of the pixel, the objective function is to minimize the spectral deviation, and the constraint condition is that the position of the pixel is within the pixel position range of the FTIR.
[0085] In this embodiment, based on the spectral deviation of each pixel calculated above, the optimization problem can be solved to obtain the position of the pixel that reaches the objective function, that is, the position of the pixel when the spectral deviation is minimized, and this position is the corrected optical axis position.
[0086] Figure 3 The flowchart of a method for correcting the off-axis angle of pixels of an FTIR provided by an embodiment of the present disclosure is shown. As Figure 3 shown, the method for correcting the off-axis angle of pixels of the FTIR includes the following steps S301 - S302:
[0087] In step S301, obtain the finally corrected optical axis position according to the above optical axis correction method;
[0088] In step S302, based on the finally corrected optical axis position, obtain the off-axis angle correction value of each pixel.
[0089] In a possible implementation manner, the method for correcting the off-axis angle of pixels of the FTIR is applicable to electronic devices such as computing devices and servers that can execute the calculation of the off-axis angle correction of the pixels of the FTIR.
[0090] In a possible implementation manner, assume that the finally corrected optical axis position obtained according to the above optical axis correction method is Substitute it into the off-axis angle calculation formula, and the off-axis angle correction value θ′ of each pixel (x, y) can be obtained (x，y) :
[0091]
[0092] Here, the correction result can be verified. For each pixel on the FTIR detector array, using the off-axis angle correction value θ′ of each pixel (x, y) (x，y) , for the wave number σ corresponding to the spectrum of the pixel (x, y) calculated above(x，y) Make corrections:
[0093] σ′ (x，y) = σ (x，y) ·cos(θ′ (x，y) );
[0094] Let the difference between σ′ (x，y) and the theoretical wave number σ T be denoted as the corrected spectral deviation dσ′ (x，y) :
[0095] dσ′ (x，y) = σ′ (x，y) - σ T ;
[0096] Figure 4 The two-dimensional matrix diagrams of each pixel and the spectral deviation before and after off-axis angle correction are shown. Among them, the left diagram (a) shows the two-dimensional matrix diagram between each pixel and the spectral deviation before off-axis angle correction, and the right diagram (b) shows the two-dimensional matrix diagram between each pixel and the spectral deviation after off-axis angle correction. These two two-dimensional matrix diagrams show the spectral deviations of 4 columns × 32 rows of pixels. The color card is used to identify the color corresponding to the spectral deviation. By comparing the two diagrams, it can be seen that the spectral deviation is significantly reduced after off-axis angle correction, and there are only some randomly distributed and very small noises, which proves that this method successfully corrects the influence of the off-axis angle.
[0097] The present disclosure also provides an optical axis correction device for FTIR, Figure 5 showing the structural block diagram of an optical axis correction device for FTIR provided by an embodiment of the present disclosure. This device can be implemented as part or all of an electronic device through software, hardware, or a combination of both. As Figure 5 shown, the optical axis correction device for FTIR includes:
[0098] A reference spectral line acquisition module 501, configured to acquire multiple reference spectral lines and their corresponding theoretical wave numbers, where the reference spectral lines include the spectral lines of predetermined atmospheric molecules within the observation spectral range of the Fourier transform infrared spectrometer FTIR;
[0099] An observed spectrum acquisition module 502, configured to perform Fourier transform on the interference data of each pixel to obtain the observed spectrum of each pixel, and the observed spectrum is the radiation digital quantization DN value corresponding to different wave numbers;
[0100] The spectral deviation acquisition module 503 is configured to, for each reference spectral line, based on the observed spectrum of each pixel, obtain the radiation DN value within the target wavenumber range in the observed spectrum of each pixel, obtain the wavenumber corresponding to the maximum radiation DN value among the radiation DN values within the target wavenumber range, and use the difference between the wavenumber corresponding to the maximum radiation DN value and the theoretical wavenumber as the spectral deviation of each pixel; the target wavenumber range is a range that is a predetermined wavenumber away from the theoretical wavenumber of the reference spectral line;
[0101] The optical axis position correction module 504 is configured to, based on the correspondence between the spectral deviation of each pixel and the correct optical axis position, obtain the corrected optical axis position according to the spectral deviation of each pixel; and obtain the finally corrected optical axis position based on the corrected optical axis positions corresponding to each reference spectral line.
[0102] In a possible implementation manner, the reference spectral line acquisition module 501 is configured to:
[0103] Based on the line-by-line radiative transfer model LBLRTM, calculate the high-resolution spectral line information of relevant atmospheric molecules within the FTIR observation spectral range under standard atmospheric conditions;
[0104] Based on the high-resolution spectral line information, select the spectral lines of CO2 and H2O molecules among the relevant atmospheric molecules in the infrared long-wave band as reference spectral lines;
[0105] Based on the spectral line information of atmospheric molecules recorded in the high-resolution transmission molecular absorption database HITRAN, obtain the theoretical wavenumber corresponding to the reference spectral line.
[0106] In a possible implementation manner, the part in the optical axis position correction module 504 that obtains the corrected optical axis position according to the spectral deviation of each pixel based on the correspondence between the spectral deviation of each pixel and the correct optical axis position is configured to:
[0107] Perform surface fitting based on the spectral deviation of each pixel to obtain a fitted surface function;
[0108] Based on the surface function, calculate the position of the pixel when the spectral deviation is the smallest as the corrected optical axis position.
[0109] In a possible implementation manner, the part in the optical axis position correction module 504 that obtains the corrected optical axis position according to the spectral deviation of each pixel based on the correspondence between the spectral deviation of each pixel and the correct optical axis position is configured to:
[0110] Construct an optimization problem, where the decision variable of the optimization problem is the position of the pixel, the objective function is to minimize the spectral deviation, and the constraint condition is that the position of the pixel is within the pixel position range of the FTIR;
[0111] Based on the spectral deviation of each pixel, solve the optimization problem, and the position of the pixel when the spectral deviation is minimized is obtained as the corrected optical axis position.
[0112] In a possible implementation manner, the part of the optical axis position correction module 504 that obtains the finally corrected optical axis position based on the corrected optical axis positions corresponding to each reference spectral line is configured as:
[0113] Perform arithmetic averaging on the corrected optical axis positions corresponding to each reference spectral line to obtain the finally corrected optical axis position.
[0114] The present disclosure also provides a device for correcting the off-axis angle of pixels of an FTIR. Figure 6 The structural block diagram of a device for correcting the off-axis angle of pixels of an FTIR provided by an embodiment of the present disclosure is shown. This device can be implemented as part or all of an electronic device through software, hardware, or a combination of both. As Figure 6 shown, the device for correcting the off-axis angle of pixels of the FTIR includes:
[0115] An optical axis correction module 601, configured to obtain the finally corrected optical axis position according to the above optical axis correction method;
[0116] An off-axis angle correction module 602, configured to obtain the off-axis angle correction value of each pixel based on the finally corrected optical axis position.
[0117] The technical terms and technical features mentioned in the embodiments of this device are the same as or similar to those mentioned in the above method embodiments. For the explanations and descriptions of the technical terms and technical features involved in this device, reference can be made to the explanations and descriptions of the above method embodiments, and details will not be repeated here.
[0118] The present disclosure also discloses an electronic device. Figure 7 The structural block diagram of an electronic device according to an embodiment of the present disclosure is shown.
[0119] As Figure 7 shown, the electronic device 700 includes a memory 701 and a processor 702. Among them, the memory 701 is used to store one or more computer instructions, and the one or more computer instructions are executed by the processor 702 to implement the method according to the embodiment of the present disclosure.
[0120] Figure 8 The structural schematic diagram of a computer system suitable for implementing the method of the embodiment of the present disclosure is shown.
[0121] As Figure 8As shown, the computer system 800 includes a processing unit 801, which can perform various processes in the above embodiments according to a program stored in a read-only memory (ROM) 802 or a program loaded from a storage section 808 into a random access memory (RAM) 803. In the RAM 803, various programs and data required for the operation of the computer system 800 are also stored. The processing unit 801, the ROM 802, and the RAM 803 are connected to each other via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.
[0122] The following components are connected to the I / O interface 805: an input section 806 including a keyboard, a mouse, etc.; an output section 807 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc. and a speaker, etc.; a storage section 808 including a hard disk, etc.; and a communication section 809 including a network interface card such as a LAN card, a modem, etc. The communication section 809 performs communication processing via a network such as the Internet. A drive 810 is also connected to the I / O interface 805 as required. A removable medium 811, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 810 as required so that a computer program read from it can be installed into the storage section 808 as required. Among them, the processing unit 801 can be implemented as a processing unit such as a CPU, a GPU, a TPU, an FPGA, an NPU, etc.
[0123] In particular, according to the embodiments of the present disclosure, the methods described above can be implemented as computer software programs. For example, the embodiments of the present disclosure include a computer program product, which includes computer instructions that, when executed by a processor, implement the method steps described above. In such an embodiment, the computer program product can be downloaded and installed from a network via the communication section 809, and / or installed from the removable medium 811.
[0124] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a part of code that contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions denoted in the blocks may occur in a different order than that denoted in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, as well as combinations of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or operations, or by a combination of dedicated hardware and computer instructions.
[0125] The units or modules described in the embodiments of the present disclosure can be implemented in software or in programmable hardware. The described units or modules can also be provided in a processor, and the names of these units or modules do not, in some cases, constitute a limitation on the units or modules themselves.
[0126] As another aspect, the present disclosure also provides a computer-readable storage medium, which can be the computer-readable storage medium included in the electronic device or computer system in the above embodiments; or it can exist separately and be a computer-readable storage medium not assembled into the device. The computer-readable storage medium stores one or more programs, and the programs are used by one or more processors to execute the methods described in the present disclosure.
[0127] The above description is only the preferred embodiments of the present disclosure and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present disclosure is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present disclosure.
Claims
1. A method for correcting the optical axis of FTIR, characterized in that Comprising: Obtaining a plurality of reference spectral lines and their corresponding theoretical wavenumbers, wherein the reference spectral lines include the spectral lines of predetermined atmospheric molecules within the FTIR observation spectral range of an infrared Fourier transform spectrometer; Performing Fourier transform on the interference data of each pixel respectively to obtain the observation spectrum of each pixel, and the observation spectrum is the radiation digital quantization (DN) value corresponding to different wavenumbers; For each reference spectral line, based on the observation spectrum of each pixel, obtaining the radiation DN value within the target wavenumber range in the observation spectrum of each pixel, obtaining the wavenumber corresponding to the maximum radiation DN value in the radiation DN values within the target wavenumber range, and taking the difference between the wavenumber corresponding to the maximum radiation DN value and the theoretical wavenumber as the spectral deviation of each pixel; the target wavenumber range is the range separated by a predetermined wavenumber from the theoretical wavenumber of the reference spectral line; Based on the correspondence between the spectral deviation of each pixel and the correct optical axis position, obtaining the corrected optical axis position according to the spectral deviation of each pixel; Based on the corrected optical axis positions corresponding to each reference spectral line, obtaining the finally corrected optical axis position.
2. The method according to claim 1, characterized in that, The obtaining of the reference spectral lines and their corresponding theoretical wavenumbers includes: Calculating the high-resolution spectral line information of relevant atmospheric molecules within the FTIR observation spectral range under standard atmospheric conditions based on the line-by-line radiative transfer model (LBLRTM); Based on the high-resolution spectral line information, selecting the spectral lines of CO2 and H2O molecules in the infrared long-wave band among the relevant atmospheric molecules as reference spectral lines; Based on the spectral line information of atmospheric molecules recorded in the high-resolution transmission molecular absorption database (HITRAN), obtaining the theoretical wavenumbers corresponding to the reference spectral lines.
3. The method according to claim 1, characterized in that The obtaining of the corrected optical axis position according to the spectral deviation of each pixel based on the correspondence between the spectral deviation of each pixel and the correct optical axis position includes: Performing surface fitting based on the spectral deviation of each pixel to obtain a fitted surface function; Based on the surface function, calculating the position of the pixel when the spectral deviation is the smallest as the corrected optical axis position.
4. The method according to claim 1, wherein The obtaining of the corrected optical axis position according to the spectral deviation of each pixel based on the correspondence between the spectral deviation of each pixel and the correct optical axis position includes: Constructing an optimization problem, where the decision variable of the optimization problem is the position of the pixel, the objective function is to minimize the spectral deviation, and the constraint condition is that the position of the pixel is within the pixel position range of the FTIR; Based on the spectral deviation of each pixel, solving the optimization problem to obtain the position of the pixel when the spectral deviation is the smallest as the corrected optical axis position.
5. The method according to claim 1, wherein The obtaining of the finally corrected optical axis position based on the corrected optical axis positions corresponding to each reference spectral line includes: Performing arithmetic averaging on the corrected optical axis positions corresponding to each reference spectral line to obtain the finally corrected optical axis position.
6. A method for correcting the pixel off-axis angle of FTIR, characterized in that, Comprising: Obtaining the finally corrected optical axis position according to the method according to any one of claims 1-5; Based on the finally corrected optical axis position, obtaining the off-axis angle correction value of each pixel.
7. An optical axis correction device for FTIR, characterized in that, Comprising: A reference spectrum acquisition module, configured to acquire multiple reference spectra and their corresponding theoretical wave numbers, where the reference spectra include the spectra of predetermined atmospheric molecules within the observation spectral range of an infrared Fourier transform spectrometer (FTIR); An observation spectrum acquisition module, configured to perform Fourier transform on the interference data of each pixel respectively to obtain the observation spectrum of each pixel, where the observation spectrum is the radiation digital quantization (DN) value corresponding to different wave numbers; A spectral deviation acquisition module, configured to, for each reference spectrum, based on the observation spectrum of each pixel, acquire the radiation DN value within the target wave number range in the observation spectrum of each pixel, acquire the wave number corresponding to the maximum radiation DN value among the radiation DN values within the target wave number range, and use the difference between the wave number corresponding to the maximum radiation DN value and the theoretical wave number as the spectral deviation of each pixel; the target wave number range is the range that is separated from the theoretical wave number of the reference spectrum by a predetermined wave number; An optical axis position correction module, configured to obtain the corrected optical axis position according to the spectral deviation of each pixel based on the correspondence between the spectral deviation of each pixel and the correct optical axis position; Based on the corrected optical axis positions corresponding to each reference spectrum, obtain the finally corrected optical axis position.
8. A pixel off-axis angle correction device for FTIR, characterized in that, Including: An optical axis correction module, configured to obtain the finally corrected optical axis position according to the method described in any one of claims 1-5; An off-axis angle correction module, configured to obtain the off-axis angle correction value of each pixel based on the finally corrected optical axis position.
9. An electronic device, characterized in that, Including a memory and a processor, where the memory is used to store one or more computer instructions, and wherein the one or more computer instructions are executed by the processor to implement the method described in any one of claims 1 to 6.
10. A readable storage medium, characterized in that, On which computer instructions are stored, and when the computer instructions are executed by a processor, the method described in any one of claims 1 to 6 is implemented.