Astrological image simulation method under constraint of in-pixel response model

Abstract

The invention discloses an astronomical image simulation method under the constraint of a pixel internal response model, and the method comprises the steps: building a detector pixel internal response function model based on a pixel internal quantum response mode of an astronomical optical detector, and adding the spatial uniformity constraint in the detector pixel internal response function model; coupling the detector pixel internal response function model with the astronomy instrument point spread function model; constructing an astronomical image effective point spread function model; pixel discretization integral sampling is carried out based on an astronomical image effective point spread function model, and an astronomical image result influenced by response non-uniformity in pixels of the detector is obtained; corresponding simulation is carried out on the basis of observation noise in the imaging process, and a final star image simulation result is obtained; the response characteristics of the detector are considered, the obtained simulated astronomical image is more reliable for celestial body measurement and luminosity measurement technology research, and especially for under-sampling astronomical image simulation, astronomical image simulation under the constraint of a response model in pixels can be effectively achieved.

Description

Technical Field

[0001] This invention relates to the field of astronomical image simulation technology, specifically a method for celestial image simulation under the constraints of an intra-pixel response model. Background Technology

[0002] Traditional astronomical image simulation software often ignores the influence of intra-pixel response inhomogeneity, assuming that the response within a pixel is uniform and only considering the spatial response inhomogeneity between pixels (i.e., flat-field simulation). However, the response within a detector pixel is actually non-uniform, with the response difference between the pixel edge and center reaching 50%, and the difference reaching 70% in the region near the pixel corner. Current research has found that astrometry and photometry of undersampled stars are affected by a systematic error related to the position of the star relative to the pixel boundary. Therefore, the influence of intra-pixel response inhomogeneity should not be ignored in star simulation, especially for undersampled stars, where this influence is more significant. Simulated star images constrained by intra-pixel response models can be used for effective astrometry and photometry research, while star simulations that ignore the effect of intra-pixel response inhomogeneity will affect the reliability of high-precision astrometry and photometry research. Therefore, star simulation methods constrained by intra-pixel response models are urgently needed. Summary of the Invention

[0003] The purpose of this invention is to provide a star simulation method under the constraint of an intra-pixel response model, so as to solve the problems existing in the above-mentioned background art.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a star simulation method under pixel-internal response model constraints, comprising: S1. Constructing the effective point spread function model of the stars: A pixel-level response function model for the detector is established based on the internal quantum response modes of the astronomical optical detector, and spatial uniformity constraints are added to the pixel-level response function model. Couple the detector pixel response function model with the astronomical instrument point spread function model; S2. Based on the effective point spread function model of the star image, pixel discretization integral sampling is performed to obtain the star image results affected by the non-uniformity of the response within the detector pixel. S3. Based on the observation noise during the imaging process, perform corresponding simulations to obtain the final star simulation results.

[0005] Preferably, the spatial uniformity constraint is as follows: The intra-pixel response function (IPRF) model for the detector based on spatial uniformity constraints is as follows: ; in, These are the coordinates of the simulated detector plane; In order to be in The internal response value of the detector pixel at the location; 'a' is the IPRF shape control parameter, and the symbol "%" indicates the remainder.

[0006] Preferably, the stellar diffuse spot produced by the diffraction of starlight by the telescope's optical system is called the instrumental point spread function (iPSF). The iPSF is usually Gaussian distributed and can therefore be written as: ; Among them, i In order to be in The point spread function of the astronomical instrument at that location; The coordinates of the star center; The dispersion of the instrument point spread function (iPSF) characterizes the shape of the star. By coupling the intra-pixel response function model (IPRF) of the detector with the point spread function model (iPSF) of the astronomical instrument, an effective point spread function model (ePSF) for the astronomical instrument is constructed.

[0007] Among them, the symbol " "" indicates convolution.

[0008] More preferably, the dispersion of the point spread function of the astronomical instrument is changed during the simulation process. It can realize star simulation under different sampling conditions.

[0009] Preferably, during the pixel discretization integral sampling process based on the star effective point spread function model, the detector pixels The sampled values ​​for the celestial phenomena are: ; in, These are the pixel coordinates of the detector; In order to be in The total number of stellar electrons at that location; This represents the total brightness of the stars.

[0010] Preferably, the formula for calculating the total brightness of the stars is: ; Where D is the diameter of the telescope; The arrival rate of photons from the measured celestial body; The internal transmission coefficient of the telescope; t is the atmospheric transmittance coefficient. exp This refers to the exposure time.

[0011] Preferably, the observation noise includes incident light shot noise, sky background shot noise, dark current shot noise, readout noise, and digital-to-analog conversion noise, and the incident light shot noise, sky background shot noise, and dark current noise all follow a Poisson distribution, the readout noise follows a normal distribution, and the digital-to-analog conversion noise follows a uniform distribution.

[0012] Preferably, the skylight background value per unit pixel is: ; Where P is the spatial angle of a pixel, measured in arcseconds; and D is the diameter of the telescope. Photon arrival rate against a 1 square arcsecond sky background; The internal transmission coefficient of the telescope; t is the atmospheric transmittance coefficient. exp This refers to the exposure time.

[0013] Preferably, by changing the photon arrival rate of the constellations This allows for the simulation of starscapes with varying brightness, resulting in starscapes with different signal-to-noise ratios.

[0014] Beneficial effects: This invention simulates the discretized integral sampling process of star images under the constraint of non-uniform response within pixels of astronomical optical detectors, and comprehensively considers the influence of various observation noises. The obtained star images can be directly applied to related astrometry and photometric research, effectively solving the simulation problem of star images under the constraint of pixel response model, providing a foundation for related research. Compared with traditional astronomical image simulation software, this method considers the response characteristics of the detector, and the obtained simulated star images are more reliable for astrometry and photometric research, especially for undersampled star image simulation. This method can effectively realize star image simulation under the constraint of pixel response model. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0016] In the attached diagram: Figure 1 This is a flowchart of the star simulation method under the constraints of the pixel-intra-pixel response model of the present invention; Figure 2 The present invention provides a simulation of the point spread function model of an astronomical instrument, the effective point spread function model of an astronomical instrument, and the astronomical result diagram using the method of this invention. Detailed Implementation

[0017] The embodiments of the present invention will now be described with reference to the accompanying drawings. The terminology used in the embodiments section is for illustrative purposes only and is not intended to limit the scope of the invention. The embodiments of this application will now be described with reference to the accompanying drawings.

[0018] Examples, such as Figure 1 As shown: A star simulation method under the constraint of an intra-pixel response model, including: S1. Constructing the effective point spread function model of the stars: A pixel-level response function model for the detector is established based on the internal quantum response modes of the astronomical optical detector, and spatial uniformity constraints are added to the pixel-level response function model. Couple the detector pixel response function model with the astronomical instrument point spread function model; For scientific research-grade astronomical detectors, the IPRF models corresponding to each pixel exhibit minimal differences and good spatial uniformity. However, the response non-uniformity within a single pixel is extremely significant (the response difference between the pixel edge and center can reach 50%, and in regions near the pixel corner, the difference can reach 70%). Therefore, the simulation of non-uniform responses within pixels cannot be ignored during star image simulation, especially for undersampled star images. The distribution of the detector pixel response in the visible light band typically approximates a Gaussian function; spatial uniformity constraints are... The intra-pixel response function (IPRF) model for the detector based on spatial uniformity constraints is as follows: ; in, These are the coordinates of the simulated detector plane; In order to be in The internal response value of the detector pixel at the location; 'a' is the IPRF shape control parameter, which is 0.5943 in this embodiment, and the symbol "%" indicates the remainder; The diffused spot of starlight produced by the diffraction of starlight through a telescope's optical system is called the instrumental point spread function (iPSF). The iPSF is typically Gaussian distributed and can therefore be written as: ; Among them, i In order to be in The point spread function of the astronomical instrument at that location; The coordinates of the star center are (2.5, 2.4) pixels in this embodiment; The dispersion of the instrument point spread function (iPSF) characterizes the shape of the star; the full width at half maximum (FWHM) of the star is equal to 2.355 times the dispersion, and in this embodiment, the full WHM of the star is taken as 0.8 pixels. By coupling the intra-pixel response function model (IPRF) of the detector with the point spread function model (iPSF) of the astronomical instrument, an effective point spread function model (ePSF) for the astronomical instrument is constructed.

[0019] Among them, the symbol " " indicates convolution; Among these methods, the dispersion of the point spread function of the astronomical instrument was changed during the simulation process. It can realize star simulation under different sampling conditions. S2. Based on the effective point spread function model of the star image, pixel discretization integral sampling is performed to obtain the star image results affected by the non-uniformity of the response within the detector pixel. Detector pixels The sampled values ​​for the celestial phenomena are: ; in, These are the pixel coordinates of the detector; In order to be in The total number of stellar electrons at that location; This represents the total brightness of the stars.

[0020] The formula for calculating the total brightness of stars is: ; Where D is the diameter of the telescope; The photon arrival rate of the celestial body being measured; by altering the photon arrival rate of the celestial bodies. It can simulate starscapes of different brightness and obtain starscapes with different signal-to-noise ratios; The internal transmission coefficient of the telescope; t is the atmospheric transmittance coefficient. exp Exposure time; S3. Based on the observation noise during the imaging process, perform corresponding simulations to obtain the final star simulation results.

[0021] The observation noise includes incident light shot noise, sky background shot noise, dark current shot noise, readout noise, and digital-to-analog conversion noise. The incident light shot noise, sky background shot noise, and dark current noise all follow a Poisson distribution, the readout noise follows a normal distribution, and the digital-to-analog conversion noise follows a uniform distribution.

[0022] The sky background value per unit pixel is: ; Where P is the spatial angle of a pixel, measured in arcseconds; and D is the diameter of the telescope. Photon arrival rate against a 1 square arcsecond sky background; The internal transmission coefficient of the telescope; t is the atmospheric transmittance coefficient. exp This refers to the exposure time.

[0023] By altering the photon arrival rate of celestial bodies To achieve star imagery simulation with different brightness levels and obtain star images with different signal-to-noise ratios; In one specific embodiment, the simulated telescope has an aperture of 2 meters, a pixel scale of 0.0736 arcseconds per pixel, and the photon arrival rate of the measured celestial object (A0 type, 550 nm band) is [missing value]. Photons / m² / s / nanometer, internal transmittance multiplied by atmospheric transmittance in the g-band is 0.759, wavelength coverage in the g-band is 146 nm, exposure time is 150 s, dark current is 0.02 electrons / s, readout noise is 5 electrons, gain is 1.4, the magnitude corresponding to background sky light per arcsecond is 23, and the full width at half maximum (FWHM) of the star image is 0.8 pixels. Based on the above methods, a star image simulation is achieved. (Reference) Figure 2 As shown, the simulated point spread function model of the astronomical instrument, the effective point spread function model of the astronomical instrument, and the astronomical results are presented. Figure 2 The image above shows a point spread model for astronomical instruments. Figure 2 The middle image: the effective point spread function model of the stars; Figure 2 The following figure shows the discretized sampling results of celestial phenomena under the influence of noise.

[0024] Traditional image simulation software simulates star phenomena based on the point spread function model of astronomical instruments. This invention considers the non-uniformity of response within detector pixels and uses an effective point spread function model of star phenomena for simulation. Figure 2 The differences between the two simulation methods are shown. The star images observed by space optical telescopes are usually undersampled star images. Therefore, it is necessary to consider the intra-pixel response inhomogeneity in the astronomical image simulation process, that is, to carry out star image simulation under the constraints of the intra-pixel response model.

[0025] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. For those skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A star simulation method under pixel-internal response model constraints, characterized in that, include: S1. Constructing the effective point spread function model of the stars: A pixel-level response function model for the detector is established based on the internal quantum response modes of the astronomical optical detector, and spatial uniformity constraints are added to the pixel-level response function model. Couple the detector pixel response function model with the astronomical instrument point spread function model; S2. Based on the effective point spread function model of the star image, pixel discretization integral sampling is performed to obtain the star image results affected by the non-uniformity of the response within the detector pixel. S3. Based on the observation noise during the imaging process, perform corresponding simulations to obtain the final star simulation results.

2. The star simulation method under the constraint of the intra-pixel response model according to claim 1, characterized in that: The spatial uniformity constraint is The intra-pixel response function (IPRF) model for the detector based on spatial uniformity constraints is as follows: ； in, These are the coordinates of the simulated detector plane; In order to be in The internal response value of the detector pixel at the location; 'a' is the IPRF shape control parameter, and the symbol "%" indicates the remainder.

3. The star simulation method under the constraint of the intra-pixel response model according to claim 1 or 2, characterized in that: By coupling the intra-pixel response function model (IPRF) of the detector with the point spread function model (iPSF) of the astronomical instrument, an effective point spread function model (ePSF) for the astronomical instrument is constructed. ； Among them, the symbol " "" indicates convolution.

4. The star simulation method under the constraint of the intra-pixel response model according to claim 3, characterized in that: During pixel discretization and integral sampling based on the star-based effective point spread function model, the detector pixels The sampled values ​​for the celestial phenomena are: ； in, These are the pixel coordinates of the detector; In order to be in The total number of stellar electrons at that location; This represents the total brightness of the stars.

5. The star simulation method under the constraint of the intra-pixel response model according to claim 4, characterized in that: The formula for calculating the total brightness of stars is: ； Where D is the diameter of the telescope; The arrival rate of photons from the measured celestial body; The internal transmission coefficient of the telescope; t is the atmospheric transmittance coefficient. exp This refers to the exposure time.

6. The star simulation method under the constraint of the intra-pixel response model according to claim 1, characterized in that: The observation noise includes incident light shot noise, sky background shot noise, dark current shot noise, readout noise, and digital-to-analog conversion noise. The incident light shot noise, sky background shot noise, and dark current noise all follow a Poisson distribution, the readout noise follows a normal distribution, and the digital-to-analog conversion noise follows a uniform distribution.

7. The star simulation method under the constraint of the intra-pixel response model according to claim 6, characterized in that: The sky background value per unit pixel is: ； Where P is the spatial angle of a pixel, measured in arcseconds; and D is the diameter of the telescope. Photon arrival rate against a 1 square arcsecond sky background; The internal transmission coefficient of the telescope; t is the atmospheric transmittance coefficient. exp This refers to the exposure time.

8. The star simulation method under the constraint of the intra-pixel response model according to claim 7, characterized in that: By altering the photon arrival rate of celestial bodies This allows for the simulation of starscapes with varying brightness, resulting in starscapes with different signal-to-noise ratios.

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