激光通信大口径地面光端机的主要作用是与卫星建立通信链路，实现卫星与地面站之间的数据传输。某激光通信车载地面光端机 600 mm主镜采用微晶材料，重量较大且工作角度不断发生变化。为保证镜面变形精度，该主镜在采用轴向背部 9点支撑的基础之上，需同时采用径向支撑结构平衡主镜在其工作角度下重力的径向分力。本文根据主镜工作角度变化，针对传统多点径向支撑结构尺寸大并易造成应力集中等问题，为平衡主镜径向重力分量，减小径向支撑结构尺寸，设计了中心轴与水银带相结合的径向支撑方案，采用有限元分析方法得出水银带参数对主镜面形的影响，优化了支撑参数并设计了支撑结构。主镜面形测试结果表明，采用本文提出的径向支撑结构后，主镜面形达到了预期效果，面形 PV值优于 λ/5，RMS值优于 λ/37，完全满足设计要求。

The main function of the laser communication large-caliber ground optical transceiver is to establish a communication link with the satellite to realize data transmission between the satellite and the ground station. The 600 mm microcrystalline primary mirror of one laser communication station is heavy, and its working angle changes constantly. In order to decrease the mirror surface error, the support system not only has a 9-pose axial support structure but also simultaneously balances the radial component of gravity of the primary mirror at its working angle by using a radial support structure. Flexible lateral support structures have large size and stress, so it is not suit for the mirror that works in a wide range of rotation. The paper researches the lateral support structure with a mercury band and central shaft, and analyses the impact of mercury band parameters on the surface error. The designed lateral structure has small size and improves the surface quality of the mirror. The measured values of PV and RMS are smaller than λ/5 and λ/37, respectively. These result shows that the designed lateral support structure reaches the design purpose and satisfies the requirements.