CN111220557B - Full-field solar reference spectrum acquisition method of hyperspectral large-field imaging spectrometer - Google Patents
Full-field solar reference spectrum acquisition method of hyperspectral large-field imaging spectrometer Download PDFInfo
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Abstract
The invention discloses a full-field solar reference spectrum acquisition method of a hyperspectral large-field-of-view imaging spectrometer, which comprises the steps of firstly selecting a standard solar spectrum with high spectral resolution, acquiring measured values of spectral response functions of the imaging spectrometer at different spectral intervals and different field intervals by adopting high-precision spectral calibration equipment in a laboratory, secondly interpolating the spectral response functions to match the sampling rate of the standard solar spectrum, then setting convolution windows corresponding to each spectral response function, adjusting convolution windows with different field intervals based on spectral curvature values, after the convolution windows are set, convolving the spectral response functions with the high-resolution solar standard spectrum in the convolution windows, thus obtaining the solar reference spectrum of each convolution window, carrying out down-sampling on the solar reference spectrum to match the spectral sampling intervals of the imaging spectrometer, and finally splicing the solar reference spectrum of each convolution window in spectral dimension, and interpolating other fields of view in the spatial dimension to obtain the solar reference spectrum of the full field of view.
Description
Technical Field
The invention belongs to the field of application of remote sensing data of a hyperspectral large-field-of-view imaging spectrometer, and particularly relates to a full-field solar reference spectrum acquisition method of the hyperspectral large-field-of-view imaging spectrometer.
Background
When the satellite-borne hyperspectral large-field-of-view imaging spectrometer remote sensing data is quantitatively applied, a solar reference spectrum without atmospheric gas absorption is required to invert an earth atmospheric scattering spectrum to obtain the concentration of atmospheric pollutants, then, when the on-orbit radiation calibration precision of the spectrometer is investigated, an instrument solar reference spectrum is required to be used as a standard input parameter, and in addition, when the imaging spectrometer is calibrated by an orbit spectrum, a Fraunhofer line of the solar reference spectrum is also required to be used as a standard spectral line for spectrum fitting. Because the spectral response function of the imaging spectrum represents the spectral response characteristic, the accurate spectral response function is the premise of obtaining the high-precision solar reference spectrum.
The satellite-borne hyperspectral large-field-of-view imaging spectrometer generally has the characteristics of high resolution (0.3-0.5nm) and large field angle (114-degree large field of view), and the detector of the spectrometer adopts an area array CCD (charge coupled device) and can acquire spectral data of spectral dimension and spatial dimension. Due to the fact that the spectral resolution of the imaging spectrometer is high, the spectral response function of the imaging spectrometer changes along with the spectral position in the spectral dimension direction, and the spectral response function also changes along with the spatial field of view due to spectral bending caused by the large field of view in the spatial dimension direction. Therefore, in order to ensure that the acquired solar reference spectrum of the imaging spectrometer can better represent the response characteristic of the imaging spectrometer, it is necessary to use an actual measurement value as a spectrum response function and consider the change condition of the actual measurement value along with the spectrum and the spatial field of view, and a full-field solar reference spectrum acquisition method of the hyperspectral large-field-of-view imaging spectrometer is provided.
The spectral response function of the imaging spectrometer OMI (ozone Monitoring Instrument) of the same type abroad at present adopts a widened gaussian function model, a solar reference spectrum is obtained based ON the model, the OMI does not consider the change of the spectral response function along with the spectral AND spatial field of view (see Marcel r. dobber, et al. ozone Monitoring Instrument calibration. ieee transport operations ON geo center AND REMOTE sensor sing,44(5),2003: 1209-.
In summary, when the imaging spectrometer acquires the solar reference spectrum, a function model such as Gaussian, Super-Gaussian, Lorentzian and the like is usually adopted as the spectral response function of the instrument, an actually measured spectral response value is not adopted, the change of the spectral response function along with the spectrum and the space field of view is not considered, the function model may not accurately represent the response characteristic of the instrument, and the deviation may exist between the solar reference spectrum acquired based on the function model and the actual response characteristic of the instrument.
Disclosure of Invention
The technical solution of the present invention is: the method adopts a spectrum response function measured value and fully considers the change of the spectrum response function along with the spectrum and the space, and can obtain the full-view spectrum reference spectrum which better represents the response characteristic of an instrument.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a full-view field solar reference spectrum acquisition method of a hyperspectral large-view field imaging spectrometer comprises the steps of selecting a standard solar spectrum with high spectral resolution, acquiring measured values of spectral response functions of the imaging spectrometer at different spectral intervals and different view field intervals in a laboratory, setting convolution windows of the spectral response functions based on spatial view field spectral curvature values, convolving the spectral response functions with the standard solar spectrum with the high spectral resolution in the convolution windows, splicing the solar reference spectrum of each convolution window in a spectral dimension after convolution is completed, interpolating the solar reference spectra in a spatial view field, and finally acquiring the full-view field solar reference spectrum of the imaging spectrometer.
The specific implementation method comprises the following steps:
firstly, selecting a high-resolution solar standard spectrum;
detecting spectral range lambda based on imaging spectrometer s The spectral resolution is also the full width at half maximum FWHM, and the SAO2010 solar spectrum is selected as the high resolution standard spectrum I (lambda) s ,Δλ s ) The spectral range of the standard solar spectrum is lambda s ，Δλ s Is the sampling interval of the standard solar spectrum.
Secondly, acquiring a spectral response function of the imaging spectrometer;
selecting a tunable laser as a high-precision spectrum calibration system, scanning the characteristic peak emitted by the tunable laser in the spectral dimension and the spatial dimension of an imaging spectrometer, and obtaining a spectral response function of R (v) l ,λ l ,λ′ l )，v l Is a spatial field of view, λ l Is the central spectral position of the spectral response function, λ' l At a central spectrum lambda for the spectral response function l The spectral ranges before and after;
thirdly, setting a convolution window;
setting the corresponding convolution window to F (v) for each spectral response function l ,λ l +δ,λ′ f )，v l Is a spatial field of view, λ l Is the central spectrum position of the spectrum response function, delta is the space field spectrum curvature value, and the spectrum curvature value delta corresponding to the central field is 0, lambda' f Is the spectral range of the convolution window;
fourthly, spectrum convolution;
first, the spectral response function R (v) l ,λ l ,λ′ l ) Interpolation is carried out, the number of interpolation points N is used for high resolution standard spectrum I (lambda) s ,Δλ s ) Is sampled at an interval delta lambda s And spectral range λ 'of the spectral response function' l Determining and interpolating to obtain a sampling interval delta lambda s Spectral response function R' (v) l ,λ l ,λ′ l ,Δλ s ). Then R' (v) l ,λ l ,λ′ l ,Δλ s ) At its corresponding convolution window F (v) l ,λ l +δ,λ′ f ) Internal and high resolution standard spectrum I (lambda) s ,Δλ s ) Convolution is carried out, and therefore the solar reference spectrums S (F, v) under different convolution windows can be obtained l ,λ l +δ,λ′ f ,Δλ s ) F is a convolution window mark, and is subjected to down-sampling to match the number of sampling points of the imaging spectrometer;
fifthly, acquiring a full-field solar reference spectrum;
solar reference spectrum S (F, v) under different convolution windows in spectral dimension pair l ,λ l +δ,λ′ f ,Δλ s ) And splicing to obtain the solar reference spectrum in the spectral dimension direction, interpolating to obtain the solar reference spectrum in the full field of view when the space field of view is tested, and finally obtaining the solar reference spectrum in the full field of view of the imaging spectrometer, wherein the solar reference spectrum corresponding to each day in one year can be obtained based on the day-to-earth distance correction.
Further, in the first step, the high-resolution solar standard spectrum is selected, and the acquisition is specifically realized as follows:
(11) determining spectral range lambda of an imaging spectrometer s And spectral resolution, i.e., full width at half maximum FWHM;
(12) spectral range lambda based on the determination s And selecting the SAO2010 solar spectrum as a high-resolution standard spectrum I (lambda) by the spectral resolution FWHM s ,Δλ s ) The spectral range is the detection spectral range lambda of the imaging spectrometer s ，Δλ s The value of the sampling interval is determined by the solar standard spectrum. I (lambda) s ,Δλ s ) The spectral resolution is 10 times better than that of the imaging spectrometer.
Further, in the second step, the acquisition of the spectral response function of the imaging spectrometer is specifically realized as follows:
(21) setting a spectral characteristic peak range output by a tunable laser to cover a spectral detection range of an imaging spectrometer;
(22) setting the spectral interval of spectral characteristic peak of tunable laser to the spectral dimension scanning of imaging spectrometer as delta lambda l Field of view spacing for spatial dimension scanning of Δ v l ；
(23) Field of view acquired is v l The central spectral position is lambda l Has a spectral response function of R (v) l ,λ l ,λ′ l ) Wherein λ' l At a central spectrum lambda for the spectral response function l The values of the front and back spectral ranges can be determined according to the full width at half maximum FWHM of the spectral response function;
further, the third step is to set a convolution window, which is specifically implemented as follows:
(31) determining a spatial dimension spectrum bending value, wherein delta is a spatial field spectrum bending value, and the spectrum bending value delta corresponding to a central field is equal to 0;
(32) setting a field of view v l The central spectral position is lambda l Spectral response function of (v) l ,λ l ,λ′ l ) Corresponding convolution window F (v) l ,λ l +δ,λ′ f ) The central wavelength position of the convolution window under different fields is corrected by a space field spectrum curvature value delta, and the spectrum curvature value delta corresponding to the central field is 0;
further, in the fourth step, the spectrum convolution is specifically realized as follows:
(41) first, the spectral response function is R (v) l ,λ l ,λ′ l ) Interpolation is carried out, the number of interpolation points N is used as the standard spectrum I (lambda) s ,Δλ s ) Is sampled at an interval delta lambda s And spectral range λ 'of the spectral response function' l Is determined, i.e.
After interpolation, the sampling interval is also delta lambda s Spectral response function R' (v) l ,λ l ,λ′ l ,Δλ s )；
(42) Spectral response function R' (v) for different fields of view and different spectral positions after interpolation l ,λ l ,λ′ l ,Δλ s ) At its corresponding convolution window F (v) l ,λ l +δ,λ′ f ) Internal and high resolution standard spectrum I (lambda) s ,Δλ s ) Convolution is carried out, and the sun reference spectrum S (F, v) under different convolution windows is obtained l ,λ l +δ,λ′ f ,Δλ s )；
(43) Down-sampling the convolution result at each convolution window to match the number of sampling points of the imaging spectrometer;
further, in the fifth step, the full-field solar reference spectrum is obtained, which is specifically realized as follows:
(51) solar reference spectra S (F, v) at spectral dimensions for different convolution windows l ,λ l +δ,λ′ f ,Δλ s ) Splicing to obtain a solar reference spectrum under the spectrum dimension;
(52) according to the methodBy which the field interval Deltav can be obtained l Lower solar reference spectrum S (v) l ,Δλ s ) The sun reference spectrum S (lambda) of the full field of view can be obtained by interpolating the sun reference spectrum s ,Δλ s )；
(53) Because the standard solar spectrum is a spectrum value under the average distance between the day and the ground, and because the change generated by the difference of the distance between the day and the ground reaches about 3 percent, the distance between the day and the ground is corrected for the solar reference spectrum of the full view field, and finally the solar reference spectrum of each day of the full view field of the imaging spectrometer is obtained.
Compared with the prior art, the invention has the advantages that:
(1) according to the invention, a high-precision spectral response function measured value obtained in a laboratory is convoluted with a high-resolution spectrum, and a function model is selected as a spectral response with the current research, so that the characterization precision of the spectral response function can be improved.
(2) The invention sets a corresponding convolution window for each spectral response function measured value of the spectral dimension, and compared with the current method of setting a convolution window for the spectral dimension, the invention can more finely control the convolution range and improve the spectral convolution precision.
(3) The invention requires that measured values of the spectral response function are obtained at certain spectral intervals in the spectral dimension and at certain angular intervals in the spatial dimension, changes of the spectral response function along with the spectrum and the space are fully considered, spectral response characteristics of the spectrometer to different spectral bands under different view field angles can be more comprehensively reflected, and further the representation precision of the full-view field solar reference spectrum of the imaging spectrometer is improved.
Drawings
FIG. 1 is a flow of acquiring a full-field solar reference spectrum of a hyperspectral large-field imaging spectrometer;
FIG. 2 is a laboratory measured value of a spectral response function of an imaging spectrometer in a spectral dimension direction obtained based on a tunable laser;
FIG. 3 is a spectral response function taken from FIG. 2 at a center wavelength of 480.0 nm.
FIG. 4 is a convolution of the interpolated measured spectral response function values of FIG. 3 in the convolution window, the convolution having been down-sampled;
FIG. 5 is a graph of spectral curvature values of an imaging spectrometer in the spatial field of view to adjust the center wavelength position of a convolution window at different fields of view;
FIG. 6 is a solar reference spectrum, for example, with a central field of view and an edge field of view, as applied to an implementation of the present invention.
Detailed Description
The invention is further described with reference to the following figures and detailed description.
As shown in fig. 1 to 6, in the present invention, a full-view solar reference spectrum of a hyperspectral large-view-field imaging spectrometer is obtained, and the full-view solar reference spectrum is obtained for the hyperspectral large-view-field imaging spectrometer, so that the problem that a spectral response function changes with a spectrum and a spatial view field due to high spectral resolution and spatial view field spectrum curvature is solved, and a full-view solar reference spectrum with higher precision and better characteristic of instrument response characteristics is obtained.
Firstly, selecting a high-resolution solar standard spectrum;
detecting spectral range lambda based on imaging spectrometer s The spectral resolution is also the full width at half maximum FWHM, and the SAO2010 solar spectrum is selected as the high resolution standard spectrum I (lambda) s ,Δλ s ) The spectral range of the standard solar spectrum is lambda s ，Δλ s Is the sampling interval of the standard solar spectrum.
Secondly, acquiring a spectral response function of the imaging spectrometer;
selecting a tunable laser as a high-precision spectrum calibration system, scanning the characteristic peak emitted by the tunable laser in the spectral dimension and the spatial dimension of an imaging spectrometer, and obtaining a spectral response function of R (v) l ,λ l ,λ′ l )，v l Is a spatial field of view, λ l Is the central spectral position of the spectral response function, λ' l At the central spectrum lambda for the spectral response function l The spectral ranges before and after;
thirdly, setting a convolution window;
setting the corresponding convolution window to F (v) for each spectral response function l ,λ l +δ,λ′ f )，v l Is a spatial field of view, λ l The central spectral position of the spectral response function is delta, the spectral curvature value of the space field is delta, and the spectral curvature value delta corresponding to the central field is 0 and lambda' f Is the spectral range of the convolution window;
fourthly, spectrum convolution;
first, the spectral response function R (v) l ,λ l ,λ′ l ) Interpolation is carried out, the number of interpolation points N is used as the standard spectrum I (lambda) s ,Δλ s ) Sampling interval of (Δ λ) s And spectral range λ 'of the spectral response function' l Determining and interpolating to obtain a sampling interval delta lambda s Spectral response function R' (v) l ,λ l ,λ′ l ,Δλ s ). Then R' (v) l ,λ l ,λ′ l ,Δλ s ) At its corresponding convolution window F (v) l ,λ l +δ,λ′ f ) Internal and high resolution standard spectrum I (lambda) s ,Δλ s ) Convolution is carried out, and therefore the solar reference spectrums S (F, v) under different convolution windows can be obtained l ,λ l +δ,λ′ f ,Δλ s ) F is a convolution window mark, and is subjected to down-sampling to match the number of sampling points of the imaging spectrometer;
fifthly, acquiring a full-field solar reference spectrum;
solar reference spectrum S (F, v) under different convolution windows in spectral dimension pair l ,λ l +δ,λ′ f ,Δλ s ) And splicing to obtain the solar reference spectrum in the spectral dimension direction, interpolating to obtain the solar reference spectrum in the full field of view when the space field of view is tested, and finally obtaining the solar reference spectrum in the full field of view of the imaging spectrometer, wherein the solar reference spectrum corresponding to each day in one year can be obtained based on the day-to-earth distance correction.
Specifically, in the first step, the high-resolution solar standard spectrum is selected, and the acquisition is specifically realized as follows:
(11) spectral range lambda corresponding to the central field of view of the imaging spectrometer in figure 2 s 400-550nm, the spectral resolution FWHM is 0.5nm, and the parameters are used for determining the selection of the standard solar spectrum;
(12) spectral range lambda based on imaging spectrometer s And spectral resolution FWHM, selecting SAO2010 solar spectrum as high resolution standard spectrum I (lambda) s ,Δλ s ) In the spectral range λ s Is 400-550nm, delta lambda s The sampling interval is 0.01nm, I (lambda) s ,Δλ s ) The spectral resolution of (2) is 10 times better than that of the imaging spectrometer.
Specifically, in the second step, the acquisition of the spectral response function of the imaging spectrometer is specifically realized as follows:
(21) setting the spectral characteristic peak range of the tunable laser to 400-550nm, wherein the spectral output precision is 10pm, which is superior to the spectral calibration precision of 500pm of an imaging spectrometer, and obtaining a high-precision spectral response function based on the laser;
(22) setting spectral interval delta lambda of spectral feature peak pair imaging spectrometer of tunable laser l 10nm, field interval Δ v for a spatial dimension scan l Fig. 2 is a result of scanning of the tunable laser in the spectral dimension direction of the central field of view of the imaging spectrometer;
(23) selected field of view v l Is a central field of view, a central spectral position lambda l Is a spectral response function R (v) at 486.0nm l ,λ l ,λ′ l ) As shown in fig. 3, the central spectrum λ l Front and rear spectral ranges λ' l 0.5nm, which can be determined from the full width at half maximum FWHM of the spectral response function 0.5 nm;
specifically, the third step is to set a convolution window, which is specifically implemented as follows:
(31) the spatial-dimensional spectral curvature value δ is shown in fig. 5, and the spectral curvature value δ corresponding to the central field of view is 0;
(32) setting a field of view v l The central spectral position is lambda l Spectral response function R (v) of l ,λ l ,λ′ l ) Corresponding convolution window F (v) l ,λ l +δ,λ′ f ) The central wavelength position of the convolution window under different fields is corrected by the space field spectrum curvature value delta, and the selected field v l Is a central field of view, a central spectral position lambda l Is a spectral response function R (v) at 486.0nm l ,λ l ,λ′ l ) Corresponding convolution window F (v) l ,λ l +δ,λ′ f ) As shown in fig. 4, the spectral curvature δ corresponding to the central field of view is 0, and the spectral range λ 'of the convolution window' f 10nm, the spectral interval Δ λ scanned by the spectral dimension l Determined at 10 nm;
specifically, the fourth step, the spectrum convolution, is specifically implemented as follows:
(41) first, the spectral response function is R (v) l ,λ l ,λ′ l ) Interpolation is carried out, the number of interpolation points N is used for high resolution standard spectrum I (lambda) s ,Δλ s ) Is sampled at an interval delta lambda s 0.01nm, spectral range λ 'of the spectral response function' l Determined at 0.5nm, i.e.
After interpolation, the sampling interval is also delta lambda s Spectral response function R' (v) l ,λ l ,λ′ l ,Δλ s )；
(42) Spectral response function R' (v) for different fields of view and different spectral positions after interpolation l ,λ l ,λ′ l ,Δλ s ) At its corresponding convolution window F (v) l ,λ l +δ,λ′ f ) Internal and high resolution standard spectrum I (lambda) s ,Δλ s ) Convolution is carried out, and the sun reference spectrum S (F, v) under different convolution windows is obtained l ,λ l +δ,λ′ f ,Δλ s ) (ii) a FIG. 4 is a view field v l Is a central field of view, a central spectral position lambda l Is the convolution window F (v) at 486.0nm l ,λ l +δ,λ′ f ) The corresponding convolution results.
(43) The convolution result at each convolution window is downsampled to match the number of sampling points of the imaging spectrometer, fig. 4 is a downsampled convolution result.
Specifically, the fifth step is to acquire a full-field solar reference spectrum, which is specifically implemented as follows:
(51) solar reference spectrum S (F) in spectral dimension for different convolution windows,v l ,λ l +δ,λ′ f ,Δλ s ) Splicing is carried out to obtain a solar reference spectrum under the spectral dimension, and the solar reference spectrum under the spectral dimension of the central view field and the edge view field is shown in figure 6;
(52) in this way, a field separation Δ v is obtained l Lower solar reference spectrum S (v) l ,Δλ s ) The sun reference spectrum S (lambda) of the full field of view can be obtained by interpolating the sun reference spectrum s ,Δλ s )；
(53) Since the standard solar spectrum is a spectrum value under the average distance between the day and the earth, and the change caused by the difference of the distance between the day and the earth reaches about 3%, the solar reference spectrum of the full field of view is corrected for the distance between the day and the earth, and finally the solar reference spectrum of each day of the full field of view of the imaging spectrometer is obtained, and fig. 6 is the solar reference spectrum under the average distance between the day and the earth.
Claims (6)
1. A full-field solar reference spectrum acquisition method of a hyperspectral large-field imaging spectrometer is characterized by comprising the following steps of:
firstly, selecting a high-resolution solar standard spectrum;
detecting spectral range lambda based on imaging spectrometer s Selecting the SAO2010 solar spectrum as a high-resolution standard spectrum I (lambda), namely a full-width-at-half maximum (FWHM) spectrum resolution s ,△λ s ) The spectral range of the standard solar spectrum is lambda s ，△λ s Is the sampling interval of the standard solar spectrum;
secondly, acquiring a spectral response function of the imaging spectrometer;
selecting a tunable laser as a high-precision spectrum calibration system, scanning the characteristic peak emitted by the tunable laser in the spectral dimension and the spatial dimension of an imaging spectrometer, and obtaining a spectral response function of R (v) l ,λ l ,λ′ l )，v l Is a spatial field of view, λ l Is the central spectral position of the spectral response function, λ' l At a central spectrum lambda for the spectral response function l The spectral ranges before and after;
thirdly, setting a convolution window;
for each spectral responseSetting the corresponding convolution window to F (v) according to the function l ,λ l +δ,λ′ f )，v l Is a spatial field of view, λ l Is the central spectral position of the spectral response function, delta is the spatial field spectral curvature value, and the central field corresponding spectral curvature value delta is 0, lambda' f Is the spectral range of the convolution window;
fourthly, spectrum convolution;
first, to the spectral response function R (v) l ,λ l ,λ′ l ) Interpolation is carried out, the number of interpolation points N is used for high resolution standard spectrum I (lambda) s ,△λ s ) Sampling interval of (A) delta lambda s And spectral range λ 'of the spectral response function' l Determining and interpolating to obtain a sampling interval of delta lambda s Spectral response function R' (v) l ,λ l ,λ′ l ,△λ s ) Then R' (v) l ,λ l ,λ′ l ,△λ s ) At its corresponding convolution window F (v) l ,λ l +δ,λ′ f ) Internal and high resolution standard spectrum I (lambda) s ,△λ s ) Convolution is carried out, and therefore the solar reference spectrum S (F, v) under different convolution windows can be obtained l ,λ l +δ,λ′ f ,△λ s ) F is a convolution window mark, and is subjected to down-sampling to match the number of sampling points of the imaging spectrometer;
fifthly, acquiring a full-field solar reference spectrum;
solar reference spectrum S (F, v) under different convolution windows in spectral dimension pair l ,λ l +δ,λ′ f ,△λ s ) And splicing to obtain the solar reference spectrum in the spectral dimension direction, interpolating to obtain the solar reference spectrum in the full field of view when the space field of view is tested, and finally obtaining the solar reference spectrum in the full field of view of the imaging spectrometer.
2. The method for acquiring the full-field solar reference spectrum of the hyperspectral large-field-of-view imaging spectrometer according to claim 1, wherein the method comprises the following steps: in the first step, a high-resolution solar standard spectrum is selected, and the acquisition is specifically realized as follows:
(11) determining spectral range lambda of an imaging spectrometer s And spectral resolution, i.e., full width at half maximum FWHM;
(12) spectral range lambda based on the determination s And selecting the SAO2010 solar spectrum as a high-resolution standard spectrum I (lambda) by the spectral resolution FWHM s ,△λ s ) The spectral range is the detection spectral range lambda of the imaging spectrometer s ，△λ s For the sampling interval, the value is determined by the solar standard spectrum, I (lambda) s ,△λ s ) The spectral resolution is 10 times better than that of the imaging spectrometer.
3. The method for acquiring the full-field solar reference spectrum of the hyperspectral large-field-of-view imaging spectrometer according to claim 1, wherein the method comprises the following steps: and step two, acquiring a spectral response function of the imaging spectrometer, which is specifically realized as follows:
(21) setting a spectral characteristic peak range output by a tunable laser to cover a spectral detection range of an imaging spectrometer;
(22) setting the spectral interval of spectral characteristic peak of tunable laser to spectral dimensional scanning of imaging spectrometer as delta lambda l Field of view spacing for spatial dimension scanning of Δ v l ；
(23) Field of view acquired is v l The central spectral position is lambda l Has a spectral response function of R (v) l ,λ l ,λ′ l ) Wherein λ' l At a central spectrum lambda for the spectral response function l The values of the spectral ranges before and after can be determined from the full width at half maximum FWHM of the spectral response function.
4. The method for acquiring the full-field solar reference spectrum of the hyperspectral large-field-of-view imaging spectrometer according to claim 1 is characterized in that: step three, setting a convolution window, which is specifically realized as follows:
(31) determining a spatial dimension spectrum bending value, wherein delta is a spatial field spectrum bending value, and a spectrum bending value delta corresponding to a central field is 0;
(32) setting a field of view v l Central lightThe spectral position is lambda l Spectral response function of (v) l ,λ l ,λ′ l ) Corresponding convolution window F (v) l ,λ l +δ,λ′ f ) The central wavelength position of the convolution window under different fields is corrected by a spatial field spectrum bending value delta, and the spectrum bending value delta corresponding to the central field is 0.
5. The method for acquiring the full-field solar reference spectrum of the hyperspectral large-field-of-view imaging spectrometer according to claim 1, wherein the method comprises the following steps: fourthly, spectrum convolution is specifically realized as follows:
(41) first, the spectral response function is R (v) l ,λ l ,λ′ l ) Interpolation is carried out, the number of interpolation points N is used for high resolution standard spectrum I (lambda) s ,△λ s ) Sampling interval of (A) delta lambda s And spectral range λ 'of the spectral response function' l Is determined, i.e. is
After interpolation, the sampling interval is obtained and is also delta lambda s Spectral response function R' (v) l ,λ l ,λ′ l ,△λ s )；
(42) Spectral response function R' (v) for different fields of view and different spectral positions after interpolation l ,λ l ,λ′ l ,△λ s ) At its corresponding convolution window F (v) l ,λ l +δ,λ′ f ) Internal and high resolution standard spectrum I (lambda) s ,△λ s ) Convolution is carried out, and the sun reference spectrum S (F, v) under different convolution windows is obtained l ,λ l +δ,λ′ f ,△λ s )；
(43) The convolution results at each convolution window are down-sampled to match the number of sample points of the imaging spectrometer.
6. The method for acquiring the full-field solar reference spectrum of the hyperspectral large-field-of-view imaging spectrometer according to claim 1, wherein the method comprises the following steps: and step five, acquiring a full-field solar reference spectrum, which is specifically realized as follows:
(51) solar reference spectra S (F, v) at spectral dimensions for different convolution windows l ,λ l +δ,λ′ f ,△λ s ) Splicing to obtain a solar reference spectrum under the spectrum dimension;
(52) in this way, the field interval Δ v can be obtained l Lower solar reference spectrum S (v) l ,△λ s ) The sun reference spectrum S (lambda) of the full field of view can be obtained by interpolating the sun reference spectrum s ,△λ s )；
(53) Because the standard solar spectrum is a spectrum value under the average distance between the day and the ground, and because the change generated by the difference of the distance between the day and the ground reaches about 3 percent, the distance between the day and the ground is corrected for the solar reference spectrum of the full view field, and finally the solar reference spectrum of each day of the full view field of the imaging spectrometer is obtained.
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