Design Of Acquisition Pointing And Focusing System For Wireless Laser Communication

Wireless laser communication(WLC)is a wireless communication technology that uses the laser beam as a carrier to realize information transmission in free space.Among them,acquisition,pointing and tracking(APT)system is the premise of wireless laser communication,and also the guarantee to maintain the stability of communication.Based on the background of coherent optical communication,this paper has conducted in-depth research on the APT system.The main contents of the work are as follows:1.The research of beaconless optical acquisition system is carried out,and analyzed the applicable conditions of different acquisition modes and scanning methods.during the establishment of the optical link,the frequency assisted use of the radio-assisted communication module to send and receive control commands between two optical communication terminals,and aiming at the communication delay caused by this module,a method for calculating the scanning reverse compensation path based on feature points is designed.Finally,the performance index of the acquisition system is analyzed in theory,including the uncertain area,probability and average capture time.2.According to the requirements of long-distance wireless laser communication for tracking accuracy,a high-precision actuator is embedded on the basis of the beaconless optical APT system to achieve high-precision tracking and aiming;Combined with the system control method,the incremental PID algorithm is used to suppress the pointing error of the actuator during the coarse alignment process;Also a focusing system is designed to assist step motor in the process of acquisition and pointing,automatic focusing control is carried out to change the spot size.3.The experiment platform of 10.21km and 100km link distance is built,and many experiments are carried out to verify the feasibility of beaconless optical APT system.The experimental results show that the beacon free optical APT system can finally achieve beam acquisition,pointing and tracking at a distance of 10.2km,in which the tracking accuracy is 27.12?rad;on the basis of the beacon free optical APT system,the 100km optical communication link is finally established by embedding the precise tracking actuator.