Dim Space Target Detection Technology Research Based On Ground-based Telescope

Ground-based telescope has become a key component of the wide-area surveillance system of space target due to its low cost,low energy consumption,high sensitivity and long detection distance.However,there are still some problems with ground-based telescopes in space target detection.Firstly,Shack-Hartmann wavefront sensor is easy to be blurred by background interference in the strong light background,which leads to the decrease of detection accuracy and signal loss.In practice,some space objects are blocked by the earth and can be observed only in the near dawn and evening.Some space objects only appear above and at the fixed place in the daytime,so there is a need to observe the space objects under the strong background condition in the actual observation.Secondly,ground-based telescopes will also be affected by scattering light and their own complex gradually vignetting to make the image nonuniformity,resulting in image quality degradation.Finally,as dense stellar background and noise usually appear in ground-based telescope imaging images,the dense stellar background and false warning points in the images bring a huge amount of data to the target detection algorithm.Therefore,ground-based telescope can provide clear and stable high-quality imaging under a strong background,and finally detect the space target quickly and accurately,which is of great significance for space target detection and perception.In this paper,the space surveillance image processing is deeply analyzed and studied,with emphasis on its application in practical engineering.The main research contents of this paper are as follows:This paper presents a hartmann sensor background suppression algorithm,which extracts the spot signal based on EM algorithm by analyzing the feature of the signal in the hartmann sensor and combining with the signal synthesis model.The performance of the algorithm in adaptive optics regulation is analyzed by simulation and experiment.The simulation and experimental results show that the method can solve the problem of signal loss and precision decline of hartmann wavefront sensor under strong background condition quickly and accurately.1.This paper deals with background suppression in Shack-Hartmann sensor under strong background.We propose a Shack-Hartmann sensor background suppression algorithm,which extracts the spot signal based on EM algorithm by analyzing the feature of the signal in the hartmann sensor and combining with the signal synthesis model.The performance of the algorithm in adaptive optics regulation is analyzed by simulation and experiment.The simulation and experimental results show that the algorithm can solve the problem of signal loss and precision decline of Shack-Hartmann wavefront sensor under strong background condition quickly and accurately.2.In this paper,the non-uniformity of ground-based telescope during imaging is studied.We proposed an image non-uniformity correction algorithm,this algorithm through the analysis of the source of non-uniformity and the its influence the image,and combining the characteristics of non-uniformity image,the algorithm can correct the image without knowing the optical system parameters and the non-uniformity model.In the case of arbitrary complex vignetting and scattering light coupling,the non-uniformity correction can be realized.Simulation and experimental results show that this algorithm can quickly and effectively suppress the influence of image nonuniformity on the distribution of image light intensity.3.In this paper,the method of ground space object detection under the background of dense stars is studied.We propose a multi-frame target detection method for groundbased telescopes in star mode and staring mode.In view of the spatial motion characteristics of background stars and space objects under these two working modes,different calculation schemes are designed for the process of multi-frame target detection from background removal to noise reduction,then to single-frame detection,and finally to multi-frame detection.This enables ground-based telescopes to effectively detect space objects in dense stellar backgrounds in two modes.The effectiveness of the method is verified by simulation and experiment,and it can meet the requirements of practical engineering.