Study On High Precision Target Detection Technology Of Plane-array Detector

In free-space laser communication and quantum communication,due to the small divergence of the space laser beam,it is necessary to use Acquisition,Tracking,and Pointing(ATP)systems to realize the construction and maintenance of communication links.The ATP system forms a closed-loop control of the tracking mechanism by using the changing of the target spot position on the plane-array detector to achieve precise tracking and pointing,which has the advantages of multi-information dimensions and window flexibility.However,the detection error of the beacon spot in the plane-array detector will directly affect the entire ATP system's tracking pointing accuracy.To meet the needs of long-distance and high-precision optical communication system in the future,this paper is oriented to the problem of high-precision acquisition,tracking and aiming of sub-microradian,mainly from the software and algorithm level to study the methods and technologies to improve the subdivision detecting accuracy of spot on the plane-array detector.This paper systematically analyzes the factors that affect the detection error of the spot position,simulates the influence of these factors on the detection accuracy,and divides the detection errors into two types: systematic error and random error according to the source,characteristics and nature to analyze the errors impact effectively,carry out experiments correctly,and process data efficiently.Facing the demand for high-precision measurement of random errors in target detection,comprehensively considering the background noise of the detector,the light intensity,the spot size and other factors,the random error measurement model of point target detection that does not depend on the point spread function of the optical system,namely the random noise equivalent angle(NEA),is established and deduced.Using this NEA can not only perform high-efficiency and high-precision quantitative measurement of random errors in spot target positioning of arbitrary shapes on the plane-array detector,but also obtain the boundary condition under which the detection errors caused by random factors can be ignored.The influence of the plane-array detector's pixel response non-uniformity on the detection accuracy was analyzed,the non-uniformity correction algorithm of the detector based on LM regression was designed,which solves the system error of the spot detection caused by the non-uniformity.Based on existing data,the pixel response models under different light intensities were established,the spot images containing different kinds of non-uniformity were generated by simulation,and the influence of non-uniformity on detection accuracy of the spot centroid was discussed.It has been verified the proposed correction algorithm has good performance by using simulation images.A ground experimental system was built to verify the proposed NEA model,pixel response model and response non-uniformity correction algorithm.Experiments of measuring the detector pixel's response curve under different light intensities and the detection accuracy of spot centroid were carried out,and the expected experimental results were obtained.Both simulation and experimental results show that the established models have higher versatility and measurement accuracy than traditional models,the proposed non-uniformity correction algorithm can achieve the expected detection accuracy: detection error is not beyond 0.025 pixel,while reducing the time and storage overhead efficiently.Research results have certain reference significance for the development of ATP system with higher precision.