Design And Research Of Optical Antenna System For Laser Communication

The development of communication technology is of vital importance to human society.In the field of space communication,with the increasing demand of communication capacity,speed and distance,the traditional microwave communication mode has been unable to meet.Space laser communication technology has become the object of vigorous development all over the world due to its advantages of large communication capacity,high communication rate,long communication distance,small size and low cost.Optical antenna is the core component of the optical system of laser communication,the performance of optical antenna has a direct impact on the quality of communication,this paper conducted the following studies based on optical antenna:Firstly,the development conditions of this field at home and abroad are fully investigated,and the development trend of this technology is summarized.Based on a pre-research project of inter-satellite laser communication,five key parameters are determined: optical aperture 150 mm,FOV ±5mrad,magnification 15 times and wavelengths of beacon emission 810 nm,beacon reception 820 nm,communication transmission 1540 nm and communication reception 1560 nm.Four different types of optical antennas are designed in this paper: Cassegrain type,RC type,off-axis tri-refiective(without folding axis mirror)and off-axis tri-trans(folding axis mirror),after comparing the comprehensive performances,Cassegrain system is selected and its tolerance analysis is carried out.Stray light in space environment will seriously affect the signal-to-noise ratio(SNR)and bit error rate(BER)of laser communication.Based on the theory of stray light transmission equation,the index of ER>40dB is determined and the reasonable design of eliminating stray light is carried out.The simulation results meet the requirements.Compared with the ground,the space environment is more complex and harsh,especially the factors such as temperature will directly affect the image quality of the optical antenna system.This paper theoretically analyses how environmental factors affect optical systems,and puts forward some countermeasures.In addition,improving the reliability of optical antenna coating is also the research object of this paper.For a practical engineering project,simulation design is far from enough,the adjustment of optical system are equally important.The steps and points of adjustment are introduced in detail.Finally,four performance tests were carried out,including wavefront aberration,exit pupil size,off-axis stray light suppression ability and magnification.The test results meet the design requirements.Based on optical antenna of laser communication terminal,the preliminary research,index determination,optical design,tolerance analysis,stray light analysis,environmental adaptability analysis,adjustment and performance test has studied,which has a certain reference value for the research in this field.