CN117390900B - Simulation method and application of seamless spectrum imaging - Google Patents
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Abstract
The invention relates to the technical field of astronomical seamless spectrum, and provides a simulation method and application of seamless spectrum imaging, wherein the method comprises the following steps: s1, calculating to obtain the corresponding relation between each level of seamless spectrum and the position and the form of the focal plane image of the detector according to the design parameters of the seamless spectrum imaging equipment and the performance parameters of the grating; s2, according to the corresponding relation, for a given multi-source seamless spectrum, carrying out dispersion on pixels on a focal plane one by one to obtain a simulation image of the spectrum on the focal plane; s3, recording the ID of the simulated celestial body falling on the pixel while carrying out dispersion on the pixel by pixel, and calculating the signal-to-noise ratio of the pixel; s4, calculating the pollution proportion of the simulated celestial body and the spectrum aliasing rate of the image of the seamless spectrum on the focal plane of the detector according to the result of pixel-by-pixel dispersion and the signal to noise ratio. The invention can determine the availability of sources and evaluate the performance of seamless spectroscopy equipment.
Description
Technical Field
The invention relates to the technical field of astronomical seamless spectrum, in particular to a simulation method and application of seamless spectrum imaging.
Background
Spectral observation plays a very important role in astronomical research, and makes research on substances in universe more stereoscopic, and provides more reliable and more real internal basis for revealing the essence of the substances. The spectrum observation instrument commonly used in astronomical observation is a seamed spectrum, but the seamed spectrum is complex to operate and has low observation efficiency for space projects, so that the seamless spectrum observation device is more used on the space astronomical observation device from the HST. And the simulation method for seamless spectrum imaging is less and less. The first version of seamless spectrum simulation software of the space station telescope developed by the applicant distributes the flow in one resolution unit of a spectrum into 80% of the area in the imaging range of the detector by using index data, so as to generate a discrete one-dimensional spectrum, and the spectrum is convolved with an image to obtain a seamless spectrum; the main work of the HST in the aspect of seamless spectrum simulation is to perform seamless spectrum simulation according to the working principle of Axe spectrum drawing software, the method mainly uses two polynomials to describe the spectrum, wherein one polynomial describes the position relationship, the other polynomial describes the relationship between the wavelength and the position, and the spectrum description is applied to an image to obtain a simulated direct spectrum image.
The first seamless spectrum simulation method is a seamless spectrum simulation method related to an index developed based on a space station telescope sky-patrol project, and the spectrum spectroscopy described by the method can only be in two directions of the vertical direction or the parallel direction of the detector, and PSF information is coupled in spectrum resolution, so that the characteristics of the seamless spectrum cannot be reflected more truly; the method of Axe is more general, but requires the measured data to fit a polynomial describing the spectrum, and the higher order of the fit increases the computational effort.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a simulation method and application of seamless spectrum imaging, according to the characteristics of a diffraction grating, the position, the form and other information of each level of seamless spectrum of theory are obtained, according to the position and the form information of the spectrum, a polynomial describing the spectrum can be directly generated for simulating a seamless spectrum image, dispersion is carried out on pixels in the simulation, after dispersion, the information such as the signal-to-noise ratio and the position of each pixel or each column of pixels in the direction of light dispersion can be directly calculated, and the definition of the information and the aliasing rate, the availability of the analysis spectrum, the performance analysis and the like are utilized.
The invention adopts the following technical scheme:
in one aspect, the invention provides a simulation method of seamless spectral imaging, comprising the following steps:
s1, calculating to obtain the corresponding relation between each level of seamless spectrum and the position and the form of the focal plane image of the detector according to the design parameters of the seamless spectrum imaging equipment and the performance parameters of the grating;
s2, according to the corresponding relation in the step S1, for a given multi-source seamless spectrum, dispersing the multi-source seamless spectrum on the focal plane of the detector one by one pixel to obtain a simulation image of the multi-source seamless spectrum on the focal plane of the detector;
s3, recording the ID of the simulated celestial body falling on the pixel while carrying out dispersion on the pixel by pixel in the step S2, and calculating the signal-to-noise ratio of the pixel;
s4, calculating pollution proportion of the simulated celestial spectrum and spectrum aliasing rate of the seamless spectrum image on the focal plane of the detector according to the pixel-by-pixel dispersion result of the step S2 and the signal to noise ratio of the step S3.
In any of the possible implementations described above, there is further provided an implementation, and the specific steps of step S1 include:
s1.1, according to design parameters of the seamless spectrum imaging equipment and performance parameters of the grating, determining the spectral characteristics of the spectrum imaging equipment, wherein the spectral characteristics comprise positions of incident lights with different wavelengths and different positions on a focal plane of the detector;
the position of the incident light with wavelength λ on the detector focal plane is calculated by:
（1）
wherein the included angle between the incident light and the main optical axis is theta 1 The angle of the large diffraction angle passing through the optical grid is theta 2 The included angle between the focal plane and the grating plane is theta 3 The distance from the grating surface to the focal surface of the detector is D, D is the line distance of the grating, m is the number of stages of grating dispersion, lambda is the wavelength, D m The position of the m-th order of the incident light with the wavelength lambda on the focal plane after passing through the grating can be expressed as the distance from the origin O, wherein the origin O is the intersection point of the normal of the incident light passing through the incidence point of the grating and the focal plane of the detector; (1) On a molecule of the formulaThe number value rule is as follows: when theta is as 1 And theta 2 Taking the sign when the normal line is on the same side, and taking the sign when the normal line is on the different side; (1) On denominator ofThe number value rule is as follows: taking the number when the included angle between the diffracted light and the focal plane of the detector is larger than 90 degrees, otherwise taking the number +sign;
s1.2, calculating the position of incident light with the start-stop wavelength of the grating on the focal plane of the detector;
the initial wavelength within a certain grating range is lambda 1 And lambda (lambda) 2 The m-order incident light lambda is calculated by the formula (1) in the step S1.1 1 And lambda (lambda) 2 Respectively at the focal plane of the detector;
s1.3 Using the detector coordinates to describe the position of the seamless Spectrum on the detector focal plane
Describing the seamless spectral position on the focal plane of the detector by using the coordinates (X, y) of the detector, the spectrum of each diffraction order is linearly distributed on the detector, and the spectrum direction forms a small included angle with the X direction of the detectorThe positional relationship of x and y is described by a linear trajectory equation:
；（2）
equation (2) above represents the dispersion trace of the spectrum on the detector, b is the intercept, b is determined by the position of the origin of the grating dispersion, and if the origin of the dispersion is the intersection point passing through the normal of the grating incidence point and the focal plane of the detector, b=0. The distance from the dispersion origin to the position of the incident light of the required wavelength on the focal plane of the detector is D calculated in (1) m On detector focal plane D m Can be expressed as:（3）。
in any one of the possible implementations as described above, there is further provided an implementation, in step S1, the design parameters of the seamless spectrum imaging apparatus include: an included angle between the main optical axis and the grating, an included angle between the grating and the focal plane of the detector, and a distance from the grating plane to the focal plane of the detector; the grating parameters include wavelength range, reticle density of the grating, and light transmission efficiency of each order of the grating.
In step S2, according to the formulas (1), (2) and (3), a correspondence between the wavelength of the incident light and the pixel on the focal plane of the detector is established; the spectrum of a given target source and the light transmission efficiency of each grade of the grating of the seamless spectrum imaging equipment are corresponding to the pixels corresponding to the focal plane of the detector according to the wavelength, and the spectrum is marked as spec1d_pix, wherein spec1d_pix is a one-dimensional spectrum calculated according to the pixel scale by dispersing continuous spectrum, and the distance between two adjacent pixels pix1 and pix2 is D m_pix1 -D m_pix2 ，D m_pix1 、D m_pix2 The positions of the pixels pix1 and pix2 on the focal plane of the detector are respectively D m The calculation method of (1), 2 and 3) is that the target source is in the extended area of the image, and each image of the areaAnd carrying out dispersion and light splitting on the elements according to the spec1d_pix, and merging the results of all the pixel dispersion and light splitting according to the image space position to obtain a simulated spectrum image.
In step S3, when the simulated spectrum image is generated by the focal plane of the detector, a matrix segment map is synchronously generated, each pixel corresponds to a list in the matrix, the list records the ID of the simulated celestial body falling at the pixel of the image, and the signal-to-noise ratio at the pixel is calculated according to the brightness of the input celestial body and the noise of the position.
Any one of the possible implementations described above further provides an implementation, in which in step S4, a proportion of a simulated celestial spectrum is contaminatedThe method comprises the following steps:
wherein,representing the number of pixels detected and aliased with each other, a>Representing the number of detected picture elements;
when a spectrum of lightThe spectrum is a usable spectrum; spectral aliasing Rate->The calculation formula of (2) is as follows:
the number of spectra that can be utilized isThe total number of spectra that can be detected is。
In any of the possible implementations described above, there is further provided an implementation, where the seamless spectral imaging device is a space station telescope seamless spectral system, and the space station telescope seamless spectrometer has three grating bands: GU (grating U band), GV (grating V band), GI (grating I band).
On the other hand, the invention also provides an application of the simulation method of the seamless spectrum imaging, in the design process of the seamless spectrum imaging equipment, the seamless spectrum imaging simulation is carried out on a plurality of groups of design parameters of the seamless spectrum imaging equipment and a plurality of groups of performance parameters of the gratings, and the corresponding spectrum aliasing rate under each design parameter is calculatedSpectral aliasing ratio is selectedAnd taking the design parameters of the seamless spectrum imaging equipment and the performance parameters of the grating corresponding to the minimum time as selected equipment parameters.
Furthermore, the simulation result can also be used for application development of actual data extraction and data analysis.
On the other hand, the invention also provides an application of the simulation method of the seamless spectrum imaging, in the design process of the seamless spectrum imaging equipment, the seamless spectrum imaging simulation is carried out on a plurality of groups of design parameters of the seamless spectrum imaging equipment and a plurality of groups of performance parameters of the gratings, and the corresponding spectrum aliasing rate under each design parameter is calculatedSpectral aliasing ratio is selectedSeamless spectrum imaging equipment design parameter corresponding to minimum timeThe number, and the performance parameters of the grating are used as selected device parameters.
The invention also provides an application of the simulation method of the seamless spectrum imaging, which uses the design parameters of the seamless spectrum imaging equipment and the performance parameters of the grating to perform seamless spectrum imaging simulation for the given seamless spectrum imaging equipment and calculate the spectrum aliasing rateAccording to spectral aliasing ratio->Imaging performance of the seamless spectral imaging apparatus was evaluated.
The invention also provides application of another simulation method of the seamless spectrum imaging, and for a given seamless spectrum imaging device, the seamless spectrum imaging simulation is carried out by using the design parameters of the seamless spectrum imaging device and the performance parameters of the grating; respectively calculating the number of observation sources without aliasing in the spectrum observed by the seamless spectrum imaging equipment at different rotation angles in the same observation direction; in the two observations of different rotation angles, the observation sources without aliasing are combined; and optimizing the rotation angle to obtain the optimal rotation angle for reducing the aliasing of the observation source by rotating a certain angle for two times in the observation direction.
On the other hand, the invention also provides an application of the simulation method of the seamless spectrum imaging, and the simulation of the seamless spectrum imaging equipment is performed, and meanwhile, the observation information of each pixel is recorded on another segment map with the same size as the simulated image, and the information can be used for analyzing the detection rate of the seamless spectrum imaging on an observation target source.
The beneficial effects of the invention are as follows:
1. according to the design characteristics of the grating type seamless spectrometer, such as the design information of the incident light direction, grating scale, the distance between the grating and the focal plane, the spectral characteristics of the spectrum are obtained.
2. And (3) carrying out dispersion on the image according to pixels by utilizing the spectral characteristics of the spectrum, and accurately placing the dispersed spectrum image into a simulation image.
3. In the above image, each pixel records information of a source, such as flow information, background information, noise information, position information, and the like of the source, analyzes the recorded information, and obtains aliasing conditions of a spectrum, detection performance of an imaging spectrometer, and the like.
4. End of simulation analysis is performed for each pixel of each source to determine the availability of the source for evaluating the performance of the seamless spectroscopy device.
Drawings
FIG. 1 is a schematic diagram of a seamless spectroscopy apparatus design.
FIG. 2 shows simulation results (150 s) of the GI band of the star center seamless spectrum in the example1 time).
FIG. 3 shows a spectral aliasing ratio and an aliasing diagram of the central region of the star, and (a) a spectral aliasing ratio and (b) an aliasing diagram.
Fig. 4 is a schematic flow chart of a simulation method of seamless spectral imaging according to an embodiment of the invention.
Detailed Description
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be regarded as being isolated, and they may be combined with each other to achieve a better technical effect.
The simulation method for seamless spectrum imaging provided by the embodiment of the invention comprises the following steps:
s1, calculating to obtain the corresponding relation between each level of seamless spectrum and the position and the form of the focal plane image of the detector according to the design parameters of the seamless spectrum imaging equipment and the performance parameters of the grating;
s2, according to the corresponding relation in the step S1, dispersing the given multi-source seamless spectrum on the focal plane one by one pixel to obtain a simulation image of the multi-source seamless spectrum on the focal plane of the detector;
s3, recording the ID of the simulated celestial body falling on the pixel while carrying out dispersion on the pixel by pixel in the step S2, and calculating the signal-to-noise ratio of the pixel;
s4, calculating pollution proportion of the simulated celestial spectrum and spectrum aliasing rate of the seamless spectrum image on the focal plane of the detector according to the pixel-by-pixel dispersion result of the step S2 and the signal to noise ratio of the step S3.
As shown in particular in fig. 4.
In one embodiment, the simulation method of seamless spectral imaging specifically operates as follows:
1) According to the design of a spectrometer, determining the spectral characteristics of the spectrometer, wherein the spectral characteristics comprise the positions of incident light with different wavelengths and different positions on the focal plane of the detector;
FIG. 1 shows a schematic diagram of a seamless spectrometer design, wherein the angle between the incident light and the main optical axis is θ 1 The angle of the large diffraction angle passing through the optical grid is theta 2 The included angle between the focal plane and the grating plane is theta 3 The distance from the grating surface to the focal surface is D, D is the line distance of the grating, m is the number of grating dispersion, lambda is the wavelength, and the diffraction equation of the diffraction grating is used according to the parametersSubstituting parameters of the spectroscopic instrument design can yield the following equation:
（1）
D m the position of the m-th order of the incident light with the wavelength lambda on the focal plane after passing through the grating is expressed as the distance from the origin O, and the origin O is the intersection point of the normal line of the incident light passing through the incidence point of the grating and the focal plane of the detector; on the molecule in the above formulaThe number value rule is as follows: when theta is as 1 And theta 2 Taking the sign when the normal line is on the same side, and taking the sign when the normal line is on the different side; in the formula +.>The number value rule is as follows: and taking the number when the included angle between the diffracted light and the focal plane of the detector is larger than 90 degrees, otherwise taking the number of plus.
2) Let the start-stop wavelength in a certain grating range be lambda 1 And lambda (lambda) 2 The m-order lambda can be obtained by the formula (1) 1 And lambda (lambda) 2 From the above formula, it can be found that the position D m Is a one-time polynomial of the variable λ, so the wavelength λ and the position D can be described herein by the expression (1) m And get the relation of the start point lambda 1 And lambda (lambda) 2 Is located at the focal plane.
3) The distances mentioned above are distance moduli, which in practice need to be described in terms of detector coordinates (x, y) if the spectral position is described in the focal plane. Depending on the characteristics of the diffraction grating, it is assumed here that the spectrum of each order of diffraction is linearly distributed over the detector, and in theory the direction of the beam split is parallel to the x-direction of the detector, and there is a certain error in the installation, resulting in a small angle between the direction of the beam split and the x-direction of the detector, but the spatial direction distribution can still be described according to a linear equation. Assuming this slight angle of departure is α, the positional relationship of x and y can be described herein as:
（2）。
4) The origins of the equations in the formulas described in (1) and (3) above are the O-point in FIG. 1, i.e., the point where the light is perpendicularly incident on the focal plane of the detector（3）。
5) Setting the x coordinate of the start and stop point position of the spectrum as x 1 And x 2 From the linear trajectory equation of equation (2), the start-stop point y coordinate y can be calculated 1 And y 2 Thus, the corresponding start-stop wavelength can be calculated according to the formulas (3) and (1), and the total track is in the range of (x) 1 ,y 1 ) And (x) 2 ,y 2 ) According to the imageSelecting a plurality of discrete points at intervals of pixel size to calculate corresponding positions, calculating corresponding wavelengths through the positions, distributing the spectrum of a target source and the light transmission efficiency of each grade of grating of the whole telescope system to the corresponding pixels according to the wavelengths, marking as Spe1d_pix, wherein Spe1d_pix is to disperse continuous spectrum into one-dimensional spectrum calculated according to pixel scale, and the distance between two adjacent pixels pix1 and pix2 is D m_pix1 -D m_pix2 ，D m_pix1 、D m_pix2 The positions of the pixels pix1 and pix2 on the focal plane of the detector are calculated by the formulas (1), (2) and (3), the target source occupies an extended area in the image, each pixel in the area is split according to spec1d_pix, and the splitting results of all the pixels are combined together according to the image space position, so that a simulated spectrum image can be obtained.
6) The above-mentioned generation of the simulated spectrum image requires the synchronous generation of segment map, the size of which is consistent with the size of the image, each position in the matrix stores a list in which the ID of the simulated celestial body falling at that position of the image is recorded, and the signal-to-noise ratio at that pixel is calculated from the brightness of the input day and the noise of that position.
7) Defining that the pixel signal to noise ratio is larger than 1 as the detected pixel, calculating the number of pixels of which the number is larger than 1 in the image of each simulated celestial body according to the segment mag defined in the step 6), and simultaneously calculating how many pixels are polluted in all the pixels of which the signal to noise ratio is larger than 1. The pollution ratio of the simulated celestial spectrum is defined in the formulaRepresenting the number of pixels detected and aliased with each other, a>Representing the number of picture elements detected, +.>The ratio of contaminated celestial spectrum of the simulation is shown:
。
8) Spectral aliasing ratio definition, assuming that the spectral aliasing ratio isDefinition of a spectrumTo be able to use the spectrum, it is necessary here to define a proportion threshold at which the spectrum is contaminated. The number of spectra that can be utilized according to the definition above is +.>The total number of spectra that can be detected isThe spectral aliasing ratio is
。
9) According to the steps 7) and 8), the number of detected celestial bodies on the whole simulation image can be obtained through statistics, and meanwhile, the number of polluted celestial bodies can be obtained, so that the simulation result can be further analyzed.
The simulation is carried out on a Chinese space station telescope seamless spectrum system, and the space station telescope seamless spectrum instrument has three grating wave bands, GU, GV and GI in total. The results of the simulation are below, and analysis for aliasing is mainly performed on the GI band. In the simulation, partial design parameters of the telescope of the Chinese space station are adopted for calculation, the reticle density of the GI wave band is 150g/mm, the distance of the grating focal plane is 64mm, the incident angle is between + -10, the wavelength range is 620nm-1000nm, the length of the primary spectrum obtained by calculation is about 3.7mm, the detector pixel is 10um, and the length on the detector is about 370 pixels. The detector and the grating are assumed to have a rotation angle of 0.5 degrees, and the slope of the track of the primary spectrum on the detector can be calculated.
According to the calculation, the track of the light can be described so as to perform simulation and analysis, the central position of the star is selected from the star table, the position is a dense star field position, the simulation of one CCD imaging is performed in the GI wave band, the number of stars input in the position is 73719, and the number of stars input in the position is 993. In the GI band, 1 exposure was performed for 150 seconds to simulate a CCD image as shown in fig. 2. The number of sources detectable on the block CCD on the dense star field was 9009, the number of stars was 565, and the number of stars was 8444, as defined above for the detected spectrum. In the simulation, the CCD size is 9232 x 9216, the pixel size is 0.074 arcsec, the CCD area is 129.42 arcmin2 according to the calculation, and the detected spectral number density is 69.8/arcmin 2. FIG. 3 shows a schematic diagram of the spectral aliasing rate statistics and aliasing for the dense star field region. The abscissa in the left graph represents the proportion of a single star that is contaminatedThe ordinate indicates the aliasing ratio of the spectrum of the whole image assuming a fixed proportion of spectral contamination +.>The method comprises the steps of carrying out a first treatment on the surface of the The right hand graph is a segment of the detected aliased spectrum, from which it can be seen that some spectra are highly contaminated and that only a small area of the spectrum is contaminated.
By using the calculation result, the design parameters of the seamless spectrometer of the space station telescope can be optimized, and the availability of the seamless spectrum can be evaluated.
The invention has specific application:
in a specific embodiment, in the design process of the seamless spectrum imaging device, seamless spectrum imaging simulation is performed on multiple groups of design parameters of the seamless spectrum imaging device and performance parameters of multiple groups of gratings, and spectrum aliasing rates corresponding to the design parameters are calculatedSelecting spectral aliasing ratio->And taking the design parameters of the seamless spectrum imaging equipment and the performance parameters of the grating corresponding to the minimum time as selected equipment parameters.
In another embodiment, for a given seamless spectral imaging device, seamless spectral imaging simulation is performed using the seamless spectral imaging device design parameters, the performance parameters of the grating, and the spectral aliasing rate is calculatedAccording to spectral aliasing ratio->Imaging performance of the seamless spectral imaging apparatus was evaluated.
In another specific embodiment, for a given seamless spectral imaging device, performing seamless spectral imaging simulation using the seamless spectral imaging device design parameters, the performance parameters of the grating; respectively calculating the number of observation sources without aliasing in the spectrum observed by the seamless spectrum imaging equipment at different rotation angles in the same observation direction; in the two observations of different rotation angles, the observation sources without aliasing are combined; and optimizing the rotation angle to obtain the optimal rotation angle for reducing the aliasing of the observation source by rotating a certain angle for two times in the observation direction.
According to the optical design of the spectrum instrument and the characteristics of the diffraction grating, the position relation of each level of the spectrum is calculated, then the position relation of the spectrum on the detector is determined according to the position relation of the detector and the grating, and meanwhile, the relation of the output wavelength and the position can be calculated according to the characteristics of the diffraction grating. According to the above relation, while considering the optical characteristics of the whole optical system and different noise sources, recording contributions of different components, etc. at the same time of simulation, the simulation ends up analyzing each pixel of each source to determine the availability of the source for evaluating the performance of the seamless spectroscopic apparatus.
Although embodiments of the present invention have been described herein, it will be appreciated by those of ordinary skill in the art that changes can be made to the embodiments herein without departing from the spirit of the invention. The above-described embodiments are exemplary only, and should not be taken as limiting the scope of the claims herein.
Claims (8)
1. A simulation method for seamless spectral imaging, the method comprising:
s1, calculating to obtain the corresponding relation between each level of seamless spectrum and the position and the form of the focal plane image of the detector according to the design parameters of the seamless spectrum imaging equipment and the performance parameters of the grating; design parameters of the seamless spectral imaging device include: an included angle between the main optical axis and the grating, an included angle between the grating and the focal plane of the detector, and a distance from the grating plane to the focal plane of the detector; the performance parameters of the grating comprise a wavelength range, the reticle density of the grating and the light transmission efficiency of each grade of the grating;
s2, according to the corresponding relation in the step S1, for a given multi-source seamless spectrum, dispersing the multi-source seamless spectrum on the focal plane of the detector one by one pixel to obtain a simulation image of the multi-source seamless spectrum on the focal plane of the detector;
s3, recording the ID of the simulated celestial body falling on the pixel while carrying out dispersion on the pixel by pixel in the step S2, and calculating the signal-to-noise ratio of the pixel;
s4, calculating pollution proportion of the simulated celestial spectrum and spectrum aliasing rate of the seamless spectrum image on the focal plane of the detector according to the pixel dispersion result of the step S2 and the signal to noise ratio of the step S3;
the specific steps of the step S1 include:
s1.1, according to design parameters of the seamless spectrum imaging equipment and performance parameters of the grating, determining the spectral characteristics of the spectrum imaging equipment, wherein the spectral characteristics comprise positions of incident lights with different wavelengths and different positions on a focal plane of the detector;
the position of the incident light with wavelength λ on the detector focal plane is calculated by:
（1）；
wherein the included angle between the incident light and the main optical axis is theta 1 The angle of the large diffraction angle passing through the optical grid is theta 2 The included angle between the focal plane and the grating plane is theta 3 The distance from the grating surface to the focal surface of the detector is D, D is the line distance of the grating, m is the number of stages of grating dispersion, lambda is the wavelength, D m The position of the m-th order of the incident light with the wavelength lambda on the focal plane after passing through the grating is expressed as the distance from the origin O, and the origin O is the intersection point of the normal line of the incident light passing through the incidence point of the grating and the focal plane of the detector; (1) On a molecule of the formulaThe number value rule is as follows: when theta is as 1 And theta 2 Taking the sign when the normal line is on the same side, and taking the sign when the normal line is on the different side; (1) In the denominator +.>The number value rule is as follows: taking the number when the included angle between the diffracted light and the focal plane of the detector is larger than 90 degrees, otherwise taking the number +sign;
s1.2, calculating the position of incident light with the start-stop wavelength of the grating on the focal plane of the detector;
the initial wavelength within a certain grating range is lambda 1 And lambda (lambda) 2 The m-order incident light lambda is calculated by the formula (1) in the step S1.1 1 And lambda (lambda) 2 Respectively at the focal plane of the detector;
s1.3, describing the position of a seamless spectrum on a focal plane of a detector by using the coordinates of the detector;
describing seamless spectrum position on focal plane of detector by adopting detector coordinate (X, y), diffraction spectrum of each level is linear distribution on detector, and light splitting direction forms an included angle with X direction of detectorThe positional relationship of x and y is described by a linear trajectory equation:
（2）；
equation (2) shows the dispersion trace of the spectrum on the detector, b is the intercept, b is determined by the position of the origin of the grating dispersion, if the origin of the dispersion is the intersection point of the normal passing through the grating incidence point and the focal plane of the detector, b=0; the distance from the start point of the dispersion to the position of the incident light of the required wavelength on the focal plane of the detector is D calculated in the formula (1) m On detector focal plane D m Expressed as:
（3）。
2. the simulation method of seamless spectral imaging according to claim 1, wherein in step S2, a correspondence between the wavelength of incident light and the pixel on the focal plane of the detector is established according to formula (1), formula (2) and formula (3); the spectrum of a given target source and the light transmission efficiency of each level of the grating of the seamless spectrum imaging device are corresponding to the corresponding pixels of the focal plane of the detector according to the wavelength, and the spectrum is recorded as spec1d_pix, wherein spec1d_pix is a one-dimensional spectrum calculated according to the pixel scale by dispersing continuous spectrums, and the distance between two adjacent pixels pix1 and pix2 is D m_pix1 -D m_pix2 ，D m_pix1 、D m_pix2 The positions of the pixels pix1 and pix2 on the focal plane of the detector are calculated by the formulas (1), (2) and (3), the target source occupies an extended area in the image, each pixel in the area is subjected to dispersion and light splitting according to spec1d_pix, and the results of dispersion and light splitting of all the pixels are combined together according to the image space position to obtain the simulated spectrum image.
3. The simulation method of seamless spectral imaging according to claim 1, wherein in step S3, when the simulated spectral image is generated at the focal plane of the detector, matrix segment mag is synchronously generated, each pixel corresponds to a list in the matrix, the list records the ID of the simulated celestial body falling at the pixel of the image, and the signal-to-noise ratio at the pixel is calculated according to the brightness of the input celestial body and the noise at the position.
4. The simulation method of seamless spectral imaging according to claim 1, wherein in step S4, a certain simulated celestial spectrum is contaminated in proportionThe method comprises the following steps:
；
wherein,representing the number of pixels detected and aliased with each other, a>Representing the number of detected picture elements;
when a simulated celestial spectrumThe simulated celestial spectrum is a spectrum that can be utilized; spectral aliasing Rate->The calculation formula of (2) is as follows:
；
the number of spectra that can be utilized isThe total number of spectra that can be detected is +.>。
5. The simulation method of seamless spectral imaging according to claim 1, wherein the seamless spectral imaging device is a space station telescope seamless spectral system, and the space station telescope seamless spectrometer has three grating bands: GU, GV and GI.
6. A method for applying the simulation method for seamless spectrum imaging according to any one of claims 1-5, wherein in the design process of the seamless spectrum imaging device, seamless spectrum imaging simulation is performed on multiple groups of design parameters of the seamless spectrum imaging device and multiple groups of performance parameters of the grating, and the corresponding spectrum aliasing rate under each design parameter is calculatedSelecting spectral aliasing ratio->And taking the design parameters of the seamless spectrum imaging equipment and the performance parameters of the grating corresponding to the minimum time as selected equipment parameters.
7. A method for applying the simulation method for seamless spectral imaging according to any one of claims 1 to 5, wherein for a given seamless spectral imaging device, seamless spectral imaging simulation is performed using the design parameters of the seamless spectral imaging device and the performance parameters of the grating, and the spectral aliasing ratio is calculatedAccording to spectral aliasing ratio->Imaging performance of the seamless spectral imaging apparatus was evaluated.
8. A method for applying the simulation method for seamless spectral imaging according to any one of claims 1 to 5, wherein for a given seamless spectral imaging device, seamless spectral imaging simulation is performed using the design parameters of the seamless spectral imaging device and the performance parameters of the grating; respectively calculating the number of observation sources without aliasing in the spectrum observed by the seamless spectrum imaging equipment at different rotation angles in the same observation direction; in the two observations of different rotation angles, the observation sources without aliasing are combined; and optimizing the rotation angle to obtain the optimal rotation angle for reducing the aliasing of the observation source by rotating a certain angle for two times in the observation direction.
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