An astronomical telescope ground test method, device, equipment and medium

Abstract

The application discloses an astronomical telescope ground test method, device, equipment and medium, and relates to the field of ground test of space optical systems, and comprises the following steps: correcting a point source array image and a dark field image sequence; superimposing the corrected dark field image sequence to generate a dark field image; deducting the dark field image from the corrected point source array image, performing connected domain analysis on the image after deducting the dark field image based on the standard deviation of the dark field image to obtain a first connected domain and a second connected domain; removing the first connected domain from the image after deducting the dark field image to obtain a target point source array image; extracting a corresponding image block from the target point source array image according to the second connected domain, performing two-dimensional Gaussian fitting on the image block, determining a point spread function based on the fitting result, generating a coordinate array by using the center coordinates corresponding to the point spread function; extracting a target image block from the target point source array image according to the coordinate array, and completing ground test on the astronomical telescope by using the target image block.

Description

Technical Field

[0001] This application relates to the field of ground testing of space optical systems, and in particular to a ground testing method, apparatus, equipment and medium for astronomical telescopes. Background Technology

[0002] Large space optical telescopes are core equipment for exploring the universe and conducting astronomical research. Their high cost and challenging on-orbit maintenance make performance verification during ground integration and testing crucial, directly determining the success or failure of on-orbit missions. Static angular resolution, a key indicator of a telescope's imaging capabilities, is accurately assessed and is a core component of ground testing. This test is typically performed by acquiring and analyzing the point spread function (PSF).

[0003] In ground testing, a dot matrix target plate is typically used to generate a point source array. After being imaged by the optical system, this point source array forms a point source array image on the detector focal plane. The point source array image is essentially a regular spatial arrangement of multiple point spread function instances, each of which carries characteristic information of the optical system under test. By calculating the 80% energy concentration angular radius of the point spread function, the static angular resolution of the telescope can be quantitatively evaluated.

[0004] However, in practical applications, interference factors such as cosmic rays and electron noise are inevitably introduced during the imaging process. These interferences are mixed with the signal regions formed by the point spread function in the image and are difficult to distinguish. Therefore, how to accurately and efficiently extract the sub-image blocks where each point spread function is located from the point source array image is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a ground-based testing method, apparatus, equipment, and medium for astronomical telescopes, capable of accurately and efficiently extracting sub-image patches containing the spread functions of each point from point source array images, thus providing support for the reliable evaluation of the telescope's static angular resolution. The specific scheme is as follows:

[0006] In a first aspect, this application provides a ground-based testing method for astronomical telescopes, including:

[0007] The point source array image and dark field image sequence acquired by the detector are corrected to obtain the corrected point source array image and dark field image sequence; the point source array image is the image obtained after the point source array is imaged by the light source illuminating the point target plate to generate the point source array; the point target plate is a target plate that is pre-set on the focal plane of the collimator of the astronomical telescope.

[0008] The corrected dark field image sequence is superimposed, and singular values ​​are removed during the superposition process to generate the target dark field image. The standard deviation of the target dark field image is then determined.

[0009] The target dark field image is subtracted from the corrected point source array image. The image after subtracting the dark field image is binarized based on the standard deviation to obtain the first target point source array image. Connectivity analysis is performed on the first target point source array image to obtain the first connected component and the second connected component. The first connected component is the connected component caused by cosmic rays, and the second connected component is the other connected components in the first target point source array image except for the first connected component.

[0010] Remove the first connected component from the first target point source array image to obtain the second target point source array image;

[0011] Based on the center coordinates of the second connected domain, the corresponding image patch is extracted from the second target point source array image. The extracted image patch is subjected to two-dimensional Gaussian fitting. The point spread function is determined based on the two-dimensional Gaussian fitting result. The coordinate array is generated using the center coordinates corresponding to the point spread function.

[0012] Using the center coordinates of each point in the coordinate array as the center, target image blocks containing the corresponding point sources are extracted from the second target point source array image, and the background area in the target image blocks is removed, so as to complete the ground test of the astronomical telescope using the obtained target point source image blocks.

[0013] Optionally, the image is corrected to obtain a corrected image, including:

[0014] The data composition of the images acquired by the detector is determined; the images acquired by the detector include point source array images and dark field image sequences. The data of the images acquired by the detector includes invalid data, pre-scan data, overscan data and actual photosensitive data. The detector contains multiple readout channels. Each readout channel independently acquires and outputs image data of the corresponding area. The image data acquired by each readout channel is summarized to form a complete frame image.

[0015] Based on the data composition, actual photosensitive data is extracted from the image acquired by the detector as valid data to be corrected.

[0016] For any reading channel, determine the mean value of overscanned data in the corresponding area of ​​the reading channel, and subtract the mean value of overscanned data from each pixel value in the valid data to be corrected corresponding to the reading channel to obtain the corrected valid data corresponding to the reading channel.

[0017] The corrected valid data from each readout channel are combined to obtain the corrected image.

[0018] Optionally, the step of superimposing the corrected dark-field image sequence and removing singular values ​​during the superposition process to generate the target dark-field image includes:

[0019] For any location in the image, statistical analysis is performed on the corrected multi-frame dark field image sequence. If any pixel value exceeds the preset reasonable pixel value range, then the pixel value is determined to be an outlier and removed.

[0020] The remaining normal pixel values ​​at any given position are superimposed to obtain the target dark field image after superimposing multiple frames of dark field image sequences.

[0021] Optionally, the step of performing connected component analysis on the first target point source array image to obtain a first connected component and a second connected component includes:

[0022] For any connected component corresponding to the first target point source array image, determine the minimum bounding rectangle of the connected component, take the length of the long side of the minimum bounding rectangle as the major axis, take the length of the short side of the minimum bounding rectangle as the minor axis, and calculate the ratio of the major axis to the minor axis.

[0023] If the ratio of the major axis to the minor axis exceeds a preset threshold, any connected component is determined to be a first connected component; if the ratio of the major axis to the minor axis does not exceed the preset threshold, any connected component is determined to be a second connected component.

[0024] Accordingly, removing the first connected component from the first target point source array image includes:

[0025] Set the pixel value corresponding to the first connected component to an invalid value to remove the first connected component from the first target point source array image.

[0026] Optionally, the step of extracting corresponding image patches from the second target point source array image based on the center coordinates of the second connected component, performing two-dimensional Gaussian fitting on the extracted image patches, determining the point spread function based on the two-dimensional Gaussian fitting result, and generating a coordinate array using the center coordinates corresponding to the point spread function includes:

[0027] The second connected components are sorted in descending order of area. The second connected component with the largest area is taken as the current connected component. The center coordinates of the current connected component are determined. Sub-image blocks of a preset size are extracted from the second target point source array image with the center coordinates as the center.

[0028] A two-dimensional Gaussian function is fitted to the sub-image block to obtain two fitting standard deviations in mutually perpendicular directions. The two fitting standard deviations are compared with a preset effective range. If both fitting standard deviations are within the preset effective range, the current connected component is determined to constitute an effective point spread function. If neither fitting standard deviation is within the preset effective range, the current connected component is determined not to constitute an effective point spread function.

[0029] Select the next connected component of the current connected component from the second connected components sorted by connected component area from largest to smallest as the new current connected component, and jump to the step of determining the center coordinates of the current connected component, until the number of effective point spread functions selected reaches a preset number threshold.

[0030] A coordinate array is generated based on the center coordinates of the selected valid point spread functions.

[0031] Optionally, the step of extracting target image patches containing corresponding point sources from the second target point source array image, centered on each center coordinate in the coordinate array, includes:

[0032] Using the center coordinates of each point in the coordinate array as the center, extract a square image block with a side length equal to the target side length value from the second target point source array image.

[0033] Optionally, removing the background region from the target image patch includes:

[0034] The target image block is divided into a point source image block located in the central region and a surrounding background region. The average value of all pixel values ​​in the background region is calculated to obtain the background mean.

[0035] Subtract the background mean from each pixel value in the point source image block to obtain the background-corrected target point source image block.

[0036] Secondly, this application provides a ground-based testing device for an astronomical telescope, comprising:

[0037] The image correction module is used to correct the point source array image and dark field image sequence acquired by the detector, respectively, to obtain the corrected point source array image and dark field image sequence; the point source array image is the image obtained after the point source array is imaged by the light source illuminating the point target plate to generate the point source array; the point target plate is a target plate that is pre-set on the focal plane of the collimator of the astronomical telescope.

[0038] The image overlay module is used to overlay the corrected dark field image sequence, remove singular values ​​during the overlay process, generate the target dark field image, and determine the standard deviation of the target dark field image.

[0039] The connected component analysis module is used to subtract the target dark field image from the corrected point source array image, perform binarization processing on the image after subtracting the dark field image based on the standard deviation to obtain a first target point source array image, and perform connected component analysis on the first target point source array image to obtain a first connected component and a second connected component; the first connected component is a connected component caused by cosmic rays, and the second connected component is other connected components in the first target point source array image besides the first connected component.

[0040] A connected component removal module is used to remove the first connected component from the first target point source array image to obtain a second target point source array image;

[0041] The function determination module is used to extract corresponding image blocks from the second target point source array image based on the center coordinates of the second connected domain, perform two-dimensional Gaussian fitting on the extracted image blocks, determine the point spread function based on the two-dimensional Gaussian fitting result, and generate a coordinate array using the center coordinates corresponding to the point spread function.

[0042] The testing module is used to extract target image blocks containing corresponding point sources from the second target point source array image, centered on each center coordinate in the coordinate array, and remove the background area in the target image blocks, so as to complete the ground test of the astronomical telescope using the obtained target point source image blocks.

[0043] Thirdly, this application provides an electronic device, comprising:

[0044] Memory, used to store computer programs;

[0045] A processor is used to execute the computer program to implement the aforementioned ground-based testing method for astronomical telescopes.

[0046] Fourthly, this application provides a computer-readable storage medium for storing a computer program, wherein the computer program, when executed by a processor, implements the aforementioned ground testing method for astronomical telescopes.

[0047] In this application, the point source array image and dark field image sequence acquired by the detector are corrected to obtain corrected point source array image and dark field image sequence; the point source array image is the image obtained after imaging the point source array by a light source illuminating a point target plate to generate a point source array, and the point target plate is a target plate pre-set on the focal plane of the collimator of the astronomical telescope; the corrected dark field image sequence is superimposed, and singular values ​​are removed during the superposition process to generate a target dark field image, and the standard deviation of the target dark field image is determined; the target dark field image is subtracted from the corrected point source array image, and the image after subtracting the dark field image is binarized based on the standard deviation to obtain a first target point source array image, and connected component analysis is performed on the first target point source array image to obtain a first connected component and a second connected component; the first... A first connected component is a connected component caused by cosmic rays, and a second connected component is any other connected component in the first target point source array image excluding the first connected component. The first connected component is removed from the first target point source array image to obtain a second target point source array image. Image patches are extracted from the second target point source array image based on the center coordinates of the second connected component. Two-dimensional Gaussian fitting is performed on the extracted image patches, and a point spread function is determined based on the two-dimensional Gaussian fitting result. A coordinate array is generated using the center coordinates corresponding to the point spread function. Target image patches containing the corresponding point sources are extracted from the second target point source array image using the center coordinates in the coordinate array as the center, and the background region in the target image patches is removed. The obtained target point source image patches are then used to complete the ground test of the astronomical telescope. As can be seen from the above, this application effectively suppresses the influence of detector inherent noise and random singular values ​​by correcting the point source array image and dark field image sequences and superimposing the corrected dark field image sequences. Furthermore, by using binarization processing based on a standard deviation threshold and connected component analysis, preliminary separation of the signal region is achieved, thereby identifying and eliminating abnormal connected components caused by cosmic rays. Next, a two-dimensional Gaussian fitting process is used to verify and filter the remaining connected components, ensuring that the extracted image conforms to the mathematical characteristics of the point spread function. Finally, through precise localization extraction and background subtraction, a clean target point source image patch is obtained, which contains the point spread function corresponding to the corresponding point source in the point source array. This application, while retaining all valid point spread functions, systematically removes various interferences, realizing the automatic and accurate extraction of high-quality point spread function data suitable for angular resolution evaluation from noisy point source array images. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0049] Figure 1 This is a flowchart of a ground testing method for an astronomical telescope disclosed in this application;

[0050] Figure 2 This is a schematic diagram of a specific ground testing method for an astronomical telescope disclosed in this application;

[0051] Figure 3 This is a schematic diagram of the structure of a ground testing device for an astronomical telescope disclosed in this application;

[0052] Figure 4 This is a schematic diagram of the structure of an electronic device disclosed in this application. Detailed Implementation

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] In practical applications, interference factors such as cosmic rays and electron noise are inevitably introduced during the imaging process. These interferences are mixed with the signal regions formed by the point spread function in the image, making them difficult to distinguish. Therefore, how to accurately and efficiently extract the sub-image blocks containing each point spread function from a point source array image is a pressing technical problem. To this end, this application provides a ground-based testing method for astronomical telescopes, which can accurately and efficiently extract the sub-image blocks containing each point spread function from a point source array image, providing support for the reliable evaluation of the telescope's static angular resolution. See also Figure 1 As shown in the figure, this application discloses a ground-based testing method for astronomical telescopes, including:

[0055] Step S11: Correct the point source array image and dark field image sequence acquired by the detector to obtain the corrected point source array image and dark field image sequence; the point source array image is the image obtained after the point source array is imaged by the light source illuminating the point target plate to generate the point source array, and the point target plate is the target plate that is set in advance on the focal plane of the collimator of the astronomical telescope.

[0056] In this embodiment, to compensate for detector readout noise and signal offset in the point source array image, the same method can be used to perform overscan correction on the point source array image and dark field image sequence acquired by the detector. Specifically, this can include: determining the data composition of the images acquired by the detector; the images acquired by the detector include point source array images and dark field image sequences, and the data of the images acquired by the detector includes invalid data, prescan data, overscan data, and actual photosensitive data. The detector contains multiple readout channels, each of which independently acquires and outputs image data for its corresponding area. The image data acquired by each readout channel is then aggregated to form a complete frame image. Among them, invalid data is redundant data not used for image processing, prescan data is reference data used for warming up the circuit before the detector acquires actual image data, overscan data is reference circuit data acquired in the area outside the effective imaging area of ​​the detector, which is not used to record the actual image but only serves as a reference circuit, and actual photosensitive data is the image data recorded in the effective imaging area of ​​the detector. Then, based on the data composition, the actual photosensitive data is extracted from the images acquired by the detector as the valid data to be corrected. For any readout channel, the mean value of the overscan data within the corresponding region of that readout channel is determined. The mean value of the overscan data is then subtracted from each pixel value in the valid data to be corrected for that readout channel to obtain the corrected valid data for that channel. Finally, the corrected valid data from each readout channel are combined to obtain the corrected image, such as... Figure 2 As shown.

[0057] Step S12: The corrected dark field image sequence is superimposed, and singular values ​​are removed during the superposition process to generate the target dark field image. The standard deviation of the target dark field image is then determined.

[0058] In this embodiment, for any position in the image, statistical analysis can be performed on the corrected multi-frame dark field image sequence. If any pixel value exceeds a preset reasonable pixel value range, that pixel value is identified as an outlier and removed. Then, the remaining normal pixel values ​​at any position can be superimposed to obtain a target dark field image that is unaffected by cosmic rays and unstable outliers after superimposing the multi-frame dark field image sequence.

[0059] Step S13: Subtract the target dark field image from the corrected point source array image, and perform binarization processing on the image after subtracting the dark field image based on the standard deviation to obtain the first target point source array image. Perform connected component analysis on the first target point source array image to obtain the first connected component and the second connected component. The first connected component is the connected component caused by cosmic rays, and the second connected component is the other connected components in the first target point source array image except for the first connected component.

[0060] In this embodiment, as Figure 2 As shown, the target dark field image can first be subtracted from the corrected point source array image. After subtraction, the image after subtracting the dark field image is binarized with a threshold of t times the standard deviation (t can be 5) to obtain the first target point source array image.

[0061] Furthermore, for any connected component corresponding to the first target point source array image, the minimum bounding rectangle of any connected component can be determined. The ratio of the major axis to the minor axis is calculated using the length of the longer side of the minimum bounding rectangle as the major axis and the length of the shorter side as the minor axis. If the ratio exceeds a preset threshold, the connected component is considered to be a connected component caused by cosmic rays and is classified as a first connected component. If the ratio does not exceed the preset threshold, the connected component is classified as a second connected component.

[0062] Step S14: Remove the first connected component from the first target point source array image to obtain the second target point source array image.

[0063] In this embodiment, the pixel values ​​corresponding to the first connected component in the first target point source array image can be set to invalid values ​​to remove the first connected component from the first target point source array image, so that these pixels do not participate in subsequent calculations such as background mean.

[0064] Step S15: Extract corresponding image blocks from the second target point source array image according to the center coordinates of the second connected domain, perform two-dimensional Gaussian fitting on the extracted image blocks, determine the point spread function based on the two-dimensional Gaussian fitting result, and generate a coordinate array using the center coordinates corresponding to the point spread function.

[0065] In this embodiment, the second connected components are first sorted in descending order of area, and the second connected component with the largest area is selected as the current connected component. The center coordinates of the current connected component are determined, and a sub-image patch of a preset size is extracted from the second target point source array image using the center coordinates as the center. Then, a two-dimensional Gaussian function is fitted to the sub-image patch to obtain two fitting standard deviations in mutually perpendicular directions. These two fitting standard deviations are compared with a preset effective range. If both fitting standard deviations are within the preset effective range, the current connected component is determined to constitute a valid point spread function; otherwise, it is determined not to constitute a valid point spread function. Further, the next connected component from the second connected components sorted in descending order of area can be selected as the new current connected component, and the process jumps to the step of determining the center coordinates of the current connected component, until the number of selected valid point spread functions reaches a preset threshold. Finally, a coordinate array can be generated based on the center coordinates of the selected valid point spread functions.

[0066] Understandably, the center coordinates of each connected region are calculated sequentially in descending order of area, and then the points are extracted from the second target point source array image using these coordinates as the center. The image patch is sized and then subjected to 2D Gaussian fitting. Here, N0 can be a small value, such as 10. The standard deviations of the Gaussian function, sigma_x and sigma_y, are obtained through fitting. If at least one of sigma_x and sigma_y is outside the range (0.5 pixels, 1.5 pixels), the current connected component is considered not to constitute a PSF and is excluded. The process continues to filter the next connected component until the number of PSFs meeting the requirements reaches a preset threshold. Simultaneously, the center coordinates corresponding to each PSF are saved. Figure 2 The obtained k sets of center coordinates form a coordinate array.

[0067] Step S16: Using the center coordinates in the coordinate array as the center, extract the target image block containing the corresponding point source from the second target point source array image, and remove the background area in the target image block, so as to complete the ground test of the astronomical telescope using the obtained target point source image block.

[0068] In this embodiment, a square image block with a side length equal to the target side length value can be extracted from the second target point source array image, using the center coordinates of each center in the coordinate array as the center. The target side length value is a side length value determined based on the first number of pixels and the second number of pixels. The spatial angle corresponding to half the number of pixels of the first number is greater than the target spatial angle, which is the spatial angle corresponding to the preset reference radius used to evaluate the energy concentration of the point source. The spatial angle corresponding to half the number of pixels of the second number is less than the target value, which is the difference between the spatial angle corresponding to half the distance between adjacent point sources and the spatial angle corresponding to the reference radius.

[0069] Furthermore, such as Figure 2 As shown, the target image patch can be divided into a point source image patch located in the central region and a surrounding background region. The average value of all pixel values ​​in the background region is calculated to obtain the background mean. Then, the background mean can be subtracted from each pixel value in the point source image patch to obtain the background-corrected target point source image patch, which can be used to complete the ground test of the astronomical telescope.

[0070] As can be seen from the above, this embodiment, through a series of operations including point source array image and dark field image sequence correction, dark field image sequence superposition and singular value removal, subtracting the dark field image from the corrected point source array image and binarizing it, deletion of connected components caused by cosmic rays, point target localization and two-dimensional Gaussian fitting to determine the point spread function, target image patch extraction, and background mean removal, systematically removes various interferences while retaining all effective point spread functions. This achieves accurate and efficient extraction of the sub-image patches containing each point spread function from the point source array image, providing support for the reliable evaluation of the telescope's static angular resolution.

[0071] See Figure 3 As shown in the embodiments, this application also discloses a ground-based testing device for an astronomical telescope, comprising:

[0072] The image correction module 11 is used to correct the point source array image and dark field image sequence acquired by the detector respectively to obtain the corrected point source array image and dark field image sequence; the point source array image is the image obtained after the point source array is imaged by the light source illuminating the point target plate to generate the point source array; the point target plate is a target plate that is set in advance on the focal plane of the collimator of the astronomical telescope.

[0073] Image overlay module 12 is used to overlay the corrected dark field image sequence, remove singular values ​​during the overlay process, generate a target dark field image, and determine the standard deviation of the target dark field image.

[0074] The connected component analysis module 13 is used to subtract the target dark field image from the corrected point source array image, perform binarization processing on the image after subtracting the dark field image based on the standard deviation to obtain a first target point source array image, and perform connected component analysis on the first target point source array image to obtain a first connected component and a second connected component; the first connected component is a connected component caused by cosmic rays, and the second connected component is other connected components in the first target point source array image besides the first connected component.

[0075] The connected component removal module 14 is used to remove the first connected component from the first target point source array image to obtain the second target point source array image;

[0076] The function determination module 15 is used to extract corresponding image blocks from the second target point source array image according to the center coordinates of the second connected domain, perform two-dimensional Gaussian fitting on the extracted image blocks, determine the point spread function based on the two-dimensional Gaussian fitting result, and generate a coordinate array using the center coordinates corresponding to the point spread function.

[0077] The test module 16 is used to extract target image blocks containing corresponding point sources from the second target point source array image with each center coordinate in the coordinate array as the center, and remove the background area in the target image blocks, so as to complete the ground test of the astronomical telescope using the obtained target point source image blocks.

[0078] In some specific embodiments, the image correction module 11 includes:

[0079] A data composition determination unit is used to determine the data composition of the images acquired by the detector. The images acquired by the detector include point source array images and dark field image sequences. The data of the images acquired by the detector includes invalid data, pre-scan data, overscan data and actual photosensitive data. The detector contains multiple readout channels. Each readout channel independently acquires and outputs image data of the corresponding area. The image data acquired by each readout channel is summarized to form a complete frame image.

[0080] The data extraction unit is used to extract actual photosensitive data from the image acquired by the detector as valid data to be corrected, based on the data composition.

[0081] The data correction unit is used to determine the average value of overscanned data in the corresponding area of ​​any reading channel for any reading channel, and to subtract the average value of overscanned data from each pixel value in the valid data to be corrected corresponding to any reading channel to obtain the corrected valid data corresponding to any reading channel.

[0082] The data combination unit is used to combine the corrected valid data from each readout channel to obtain the corrected image.

[0083] In some specific embodiments, the image overlay module 12 includes:

[0084] The pixel value analysis unit is used to perform statistical analysis on the corrected multi-frame dark field image sequence for any position in the image. If any pixel value exceeds the preset reasonable pixel value range, the pixel value is determined to be an outlier and removed.

[0085] The overlay unit is used to perform an overlay operation on the remaining normal pixel values ​​at any position to obtain a target dark field image after overlaying multiple frames of dark field image sequences.

[0086] In some specific embodiments, the connected component analysis module 13 includes:

[0087] The ratio determination unit is used to determine the minimum bounding rectangle of any connected component corresponding to the first target point source array image, and to calculate the ratio of the long side length of the minimum bounding rectangle as the major axis and the short side length of the minimum bounding rectangle as the minor axis.

[0088] The first connected component determination unit is used to determine any connected component as a first connected component if the ratio of the major axis to the minor axis exceeds a preset threshold, and to determine any connected component as a second connected component if the ratio of the major axis to the minor axis does not exceed the preset threshold.

[0089] Accordingly, the connected component removal module 14 includes:

[0090] The connected component removal unit is used to set the pixel value corresponding to the first connected component to an invalid value in order to remove the first connected component from the first target point source array image.

[0091] In some specific embodiments, the function determination module 15 includes:

[0092] The first image block extraction unit is used to sort the second connected domains in descending order of connected domain area, take the second connected domain with the largest area as the current connected domain, determine the center coordinates of the current connected domain, and extract sub-image blocks of a preset size from the second target point source array image with the center coordinates as the center.

[0093] The second connected component determination unit is used to perform two-dimensional Gaussian function fitting on the sub-image block to obtain two fitting standard deviations in mutually perpendicular directions. The two fitting standard deviations are compared with a preset effective range. If both fitting standard deviations are within the preset effective range, the current connected component is determined to constitute an effective point spread function. If the two fitting standard deviations are not within the preset effective range, the current connected component is determined not to constitute an effective point spread function.

[0094] The loop unit is used to select the next connected component of the current connected component as the new current connected component from the second connected components sorted by the area of ​​the connected components in descending order, and jump to the step of determining the center coordinates of the current connected component until the number of effective point spread functions selected reaches a preset number threshold.

[0095] The coordinate array generation unit is used to generate a coordinate array based on the center coordinates of the selected valid point spread function.

[0096] In some specific embodiments, the test module 16 includes:

[0097] The second image block extraction unit is used to extract square image blocks with a side length equal to the target side length value from the second target point source array image, centered on each center coordinate in the coordinate array.

[0098] In some specific embodiments, the test module 16 includes:

[0099] The background mean value determination unit is used to split the target image block into a point source image block located in the central region and a surrounding background region, calculate the average value of all pixel values ​​in the background region, and obtain the background mean value.

[0100] The background mean removal unit is used to subtract the background mean from each pixel value in the point source image block to obtain the target point source image block after background correction.

[0101] Furthermore, embodiments of this application also disclose an electronic device, Figure 4 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content of the diagram should not be construed as limiting the scope of this application.

[0102] Figure 4 This is a schematic diagram of the structure of an electronic device 20 provided in an embodiment of this application. Specifically, the electronic device 20 may include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 stores a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the ground-based testing method for astronomical telescopes disclosed in any of the foregoing embodiments. Alternatively, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0103] In this embodiment, the power supply 23 is used to provide operating voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and external devices, and the communication protocol it follows can be any communication protocol applicable to the technical solution of this application, and is not specifically limited here; the input / output interface 25 is used to acquire external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs, and is not specifically limited here.

[0104] In addition, the memory 22, as a carrier for resource storage, can be a read-only memory, random access memory, disk or optical disk, etc. The resources stored thereon can include operating system 221, computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0105] The operating system 221 is used to manage and control the various hardware devices on the electronic device 20 and the computer program 222, which may be Windows Server, Netware, Unix, Linux, etc. In addition to including a computer program capable of performing the ground-based astronomical telescope testing method executed by the electronic device 20 as disclosed in any of the foregoing embodiments, the computer program 222 may further include computer programs capable of performing other specific tasks.

[0106] Furthermore, this application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, it implements the aforementioned disclosed ground-based testing method for astronomical telescopes. Specific steps of this method can be found in the corresponding content disclosed in the foregoing embodiments, and will not be repeated here.

[0107] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0108] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0109] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0110] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0111] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A ground-based testing method for astronomical telescopes, characterized in that, include: The point source array image and dark field image sequences acquired by the detector are corrected to obtain the corrected point source array image and dark field image sequences. The point source array image is the image obtained after the point source array is imaged by a light source illuminating a point source target plate. The point source target plate is a target plate that is pre-set on the focal plane of the collimator of the astronomical telescope. The corrected dark field image sequence is superimposed, and singular values ​​are removed during the superposition process to generate the target dark field image. The standard deviation of the target dark field image is then determined. The target dark field image is subtracted from the corrected point source array image. The image after subtracting the dark field image is binarized based on the standard deviation to obtain the first target point source array image. Connectivity analysis is performed on the first target point source array image to obtain the first connected component and the second connected component. The first connected component is the connected component caused by cosmic rays, and the second connected component is the other connected components in the first target point source array image except for the first connected component. Remove the first connected component from the first target point source array image to obtain the second target point source array image; Based on the center coordinates of the second connected domain, the corresponding image patch is extracted from the second target point source array image. The extracted image patch is subjected to two-dimensional Gaussian fitting. The point spread function is determined based on the two-dimensional Gaussian fitting result. The coordinate array is generated using the center coordinates corresponding to the point spread function. Using the center coordinates of each point in the coordinate array as the center, target image blocks containing the corresponding point sources are extracted from the second target point source array image, and the background area in the target image blocks is removed, so as to complete the ground test of the astronomical telescope using the obtained target point source image blocks.

2. The ground-based testing method for astronomical telescopes according to claim 1, characterized in that, The image is corrected to obtain the corrected image, including: The data composition of the images acquired by the detector is determined; the images acquired by the detector include point source array images and dark field image sequences. The data of the images acquired by the detector includes invalid data, pre-scan data, overscan data and actual photosensitive data. The detector contains multiple readout channels. Each readout channel independently acquires and outputs image data of the corresponding area. The image data acquired by each readout channel is summarized to form a complete frame image. Based on the data composition, actual photosensitive data is extracted from the image acquired by the detector as valid data to be corrected. For any reading channel, determine the mean value of overscanned data in the corresponding area of ​​the reading channel, and subtract the mean value of overscanned data from each pixel value in the valid data to be corrected corresponding to the reading channel to obtain the corrected valid data corresponding to the reading channel. The corrected valid data from each readout channel are combined to obtain the corrected image.

3. The ground-based testing method for astronomical telescopes according to claim 1, characterized in that, The step of superimposing the corrected dark-field image sequence, removing singular values ​​during the superposition process, and generating the target dark-field image includes: For any location in the image, statistical analysis is performed on the corrected multi-frame dark field image sequence. If any pixel value exceeds the preset reasonable pixel value range, then the pixel value is determined to be an outlier and removed. The remaining normal pixel values ​​at any given position are superimposed to obtain the target dark field image after superimposing multiple frames of dark field image sequences.

4. The ground-based testing method for astronomical telescopes according to claim 1, characterized in that, The step of performing connected component analysis on the first target point source array image to obtain a first connected component and a second connected component includes: For any connected component corresponding to the first target point source array image, determine the minimum bounding rectangle of the connected component, take the length of the long side of the minimum bounding rectangle as the major axis, take the length of the short side of the minimum bounding rectangle as the minor axis, and calculate the ratio of the major axis to the minor axis. If the ratio of the major axis to the minor axis exceeds a preset threshold, any connected component is determined to be a first connected component; if the ratio of the major axis to the minor axis does not exceed the preset threshold, any connected component is determined to be a second connected component. Accordingly, removing the first connected component from the first target point source array image includes: Set the pixel value corresponding to the first connected component to an invalid value to remove the first connected component from the first target point source array image.

5. The ground-based testing method for astronomical telescopes according to claim 1, characterized in that, The step of extracting corresponding image patches from the second target point source array image based on the center coordinates of the second connected component, performing two-dimensional Gaussian fitting on the extracted image patches, determining the point spread function based on the two-dimensional Gaussian fitting result, and generating a coordinate array using the center coordinates corresponding to the point spread function includes: The second connected components are sorted in descending order of area, and the second connected component with the largest area is taken as the current connected component. The center coordinates of the current connected component are determined, and a sub-image block of a preset size is extracted from the second target point source array image with the center coordinates as the center. A two-dimensional Gaussian function is fitted to the sub-image block to obtain two fitting standard deviations in mutually perpendicular directions. The two fitting standard deviations are compared with a preset effective range. If both fitting standard deviations are within the preset effective range, the current connected component is determined to constitute an effective point spread function. If neither fitting standard deviation is within the preset effective range, the current connected component is determined not to constitute an effective point spread function. Select the next connected component of the current connected component from the second connected components sorted by connected component area from largest to smallest as the new current connected component, and jump to the step of determining the center coordinates of the current connected component, until the number of effective point spread functions selected reaches a preset number threshold. A coordinate array is generated based on the center coordinates of the selected valid point spread functions.

6. The ground-based testing method for astronomical telescopes according to claim 1, characterized in that, The step of extracting target image patches containing corresponding point sources from the second target point source array image, centered on each center coordinate in the coordinate array, includes: Using the center coordinates of each point in the coordinate array as the center, extract a square image block with a side length equal to the target side length value from the second target point source array image.

7. The ground-based testing method for astronomical telescopes according to claim 1, characterized in that, Removing the background region from the target image block includes: The target image block is divided into a point source image block located in the central region and a surrounding background region. The average value of all pixel values ​​in the background region is calculated to obtain the background mean. Subtract the background mean from each pixel value in the point source image block to obtain the background-corrected target point source image block.

8. A ground-based testing device for an astronomical telescope, characterized in that, include: The image correction module is used to correct the point source array image and dark field image sequence acquired by the detector, respectively, to obtain the corrected point source array image and dark field image sequence. The point source array image is the image obtained after the point source array is imaged by a light source illuminating a point source target plate. The point source target plate is a target plate that is pre-set on the focal plane of the collimator of the astronomical telescope. The image overlay module is used to overlay the corrected dark field image sequence, remove singular values ​​during the overlay process, generate the target dark field image, and determine the standard deviation of the target dark field image. The connected component analysis module is used to subtract the target dark field image from the corrected point source array image, perform binarization processing on the image after subtracting the dark field image based on the standard deviation to obtain a first target point source array image, and perform connected component analysis on the first target point source array image to obtain a first connected component and a second connected component; the first connected component is a connected component caused by cosmic rays, and the second connected component is other connected components in the first target point source array image besides the first connected component. A connected component removal module is used to remove the first connected component from the first target point source array image to obtain a second target point source array image; The function determination module is used to extract corresponding image blocks from the second target point source array image based on the center coordinates of the second connected domain, perform two-dimensional Gaussian fitting on the extracted image blocks, determine the point spread function based on the two-dimensional Gaussian fitting result, and generate a coordinate array using the center coordinates corresponding to the point spread function. The testing module is used to extract target image blocks containing corresponding point sources from the second target point source array image, centered on each center coordinate in the coordinate array, and remove the background area in the target image blocks, so as to complete the ground test of the astronomical telescope using the obtained target point source image blocks.

9. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the ground testing method for astronomical telescopes as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, Used to store a computer program, which, when executed by a processor, implements the ground testing method for astronomical telescopes as described in any one of claims 1 to 7.

Images