Characteristic Of Temperature Change On Optical Antenna Of Satellite Laser Communication Terminals

The satellite is greatly affected by the space environment during on-orbitoperation. To be specific the space environment directly causes uneven temperaturedistribution and deformation on optical elements. Optical element，the core memberof the satellite laser communication system, whose deformation affects the qualityof the transmission beam, and then seriously affecting the communication quality.Therefore, the impact study of the satellite laser communication by the variedtemperature field is of great significance for optimizing the performance of satellitelaser communication systems and improving the communication quality.This paper bases on from a designed reflective Cassegrain system. Themechanical support structure of optical element is designed. The finite elementanalysis model is used to study the temperature characteristics of the opticalsystemwhose primary and secondary mirrors, which are heated by different shapes ofthe heating sheet, and with different materials. This characterized the temperaturedistribution of the primary and secondary mirror and deformation with thermalloading. The obtaineds the mirrors’ deformationis used fitting Zernike xoefficient. Theanalysis of the system’s wavefront distortion, spot energy distribution, MTF, etc, areby using CODE V. Simultaneously the comparing of is performed in two opticalsystems with materials are Zerodur and K9, respectively. The specific work asfollows:The supporting structures of the optical system, which includs the main mirrorbase and the secondary mirror holder is designed. The primary and secondary mirrorsconnected by using the three–point support formation. The brackets and secondarymirror base is made of the same material with incision form. Primary mirror baseswith surrounding support mode. The primary mirror and secondary mirror holderbases materials are using Zerodur and k9, respectively. The support structuredesigning substantializes the optical system.The optical system’s finite element analysis model is established. And thetemperature characteristics of the optical systemis analyzed by simulation. The mainmirror is heated in three different ways on the back, which materials are Zerodur andK9, respectively. The analysis of three types of heating formation obtained the valuesof plate temperaturefiels and deformation fields, and both of the walues are of linearlywith increasing temperature increments.The deformation effect on the optical performance of the system is analysed. Thedeformation of the optical system is obtained by fitting Zernike coefficient. Then theCODE V optical analysis is used to get the system’s wavefront distortion, and spotenergy distribution, MTF value, etc.The optical characteristics are obtained from comparative analysis of threedifferent shapes heating sheet. The impace of optical system beam quality with radial shape heating sheet is least, and the circumferential shape with same area impace lessthan circumferetial shape with same diameter. And Zerodur material system withsmaller impact in optical beam quality when compare with the K9, which are heatedby the same heating source.In summary, the temperature stability of the optical antenna is an importantindicator of space optical communication systems. This paper provides the assistanceof designing the reflective Cassegrain thermal control system, and primarily selectingthe shape of the heating plate.