The Precision Detection Technology Of Laser Spot In Space Laser Communication System

With the development of space technology,space laser communications with high speed,small size and good confidentiality have become the most potential communication modes in spatial information transmission.In space laser communication,it is very difficult to achieve accurate alignment of the optical axis in the case of long-distance and double-end high-speed motion because the laser beam has small dispersion angle.This paper introduces the current development of space laser communication both at home and abroad,introduces the working principle,major technology and performance of the APT subsystem system.Based on this research,several methods that can be used for spot position detection are studied,and their working principles and advantages and disadvantages are mainly analyzed.In order to simplify the volume of the communication system and improve the tracking accuracy,a spot position detection system based on laser nutation technology was proposed.The computational process of spot miss distance in laser nutation technology was studied,and the influence of different nutation amplitude,sampling frequency and nutation frequency on the accuracy of miss distance was analyzed.A simulation model of spot miss distance calculation was established and simulation analysis was performed using Matlab.The theoretical calculation results show that the detection accuracy of spot miss distance is about 0.02 ?m,and the corresponding angular accuracy is 1.1 ?rad,which meets the requirements of the system for tracking accuracy.In-depth study of each unit of laser nutation system,designed and completed hardware circuit design and debugging work.The experimental test system was set up in the laboratory.The 1550 nm wavelength and the avalanche photodiode were used as the detector to test the accuracy of miss distance.At the same time,the factors influencing the spot detection accuracy were analyzed and verified in detail.The test results show that the detection accuracy of spot miss distance is 0.05?m and the corresponding angular accuracy is 2.71?rad,which verifies the feasibility of using laser nutation technology for spot detection and provides technical support for the miniaturization design of space laser communication system.