Research On High Precision Aiming Technology For Target In Atmospheric Turbulence

Due to the advantages of high transmission rate,large capacity and high security and so on,satellite to earth laser communication is one of the options for efficient and secure communication in the future,and has a good future in military defense and commerce.Therefore,it is of great significance to make research on key technology of satellite to earth laser communication,the high precision pointing technology is most important which ensure the establishment and maintenance of communication link.For the problem,in-depth theoretical analysis and experimental verification are carried out in this paper.For the first,in order to provide theoretical reference for the estimation for the pointing error caused by atmospheric disturbance,the effect of atmospheric attenuation and turbulence on the propagation of laser is theoretically analyzed.And atmospheric refraction model is established by the method of atmospheric stratification.On this basis,the dispersion compensation method is proposed.Secondly,the theoretical analysis is carried out for the aiming technical scheme that base on G-tilt detectionan Z-tilt detection.The pointing error that caused by tilt anisoplanatism is analysed by the spatial spectrum filtering and Mellin transform.Theoretical analysis shows that tilt correction factor can be briefed as?r₀ L₀^t?^5/3,where r₀ and ^tL₀ is the atmospheric coherence lengt and equivalent atmospheric coherence lengt,respectively.Simulation analysis shows that the theoretical limit performance of the aiming system is better for small ahead-point angle and large aperture.And theoretical limit performance of the aiming system will be reduced with the worsen of atmospheric condition.Again,the satellite orbit dynamics model that based on TLE ephemeris is established for the analysis of motion characteristics of satellite in the horizontal coordinate system and point-ahead angle.The effect of angular acceleration,angular velocity error,system working frequency and time delay on point-ahead angle is studied.And correction algorithm is carried out for those error factors.Then,by the method of directional characteristics of plane mirror imaging and prism rotation theorem,the view field rotation that caused by alt-az telescope is studied.And the offset aiming model that based on despun compensation is established.Final,two methods of axle differential calibration are proposed and applied to the reality system.Under atmospheric condition,replication experiments are performed combine with the static target that over 1km and the dynamic target.The results show that the aiming errors of the two experiments are less than 1?rad.