空间激光通信终端通常依靠光学天线提高整个通信系统的发射及接收效率。提出了一种空间激光通信系统的离轴天线系统，以克服传统卡塞格林两镜系统存在接收视场小、发射效率低等缺点。设计了一个通光孔径为150 mm，放大倍率为15×，满足0.85、1.064、1.55 μm多个通信波段光学天线系统。计算了初始结构参数，利用光学设计软件ZEMAX-EE对该光学天线系统进行了光线追迹和优化设计，并对设计结果进行分析。分析结果表明：在整个工作波段(0.85、1.064、1.55 μm)内，点列图半径几何值小于10 μrad，实现了高放大倍率、宽波段像散同时校正，在宽波段内均达到衍射极限，满足设计指标要求，能够满足高性能空间激光通信系统的要求。

Space optical communications terminals frequently rely on optical telescopes to enhance the transmitted and received efficiency of the communication system. An optical design of a space laser communications optical antenna system was proposed to overcome the traditional on-axis Cassegrain optical antenna′s disadvantages of small field of view and low emission efficiency. As an example, an optical antenna system operating at 0.85 μm, 1.064 μm and 1.55 μm with aperture size 150 mm, magnification 15 was designed. The initial parameters were computed, and the ray tracing and optimization for the optical antenna system were performed with ZEMAX-EE software. The analysis results demonstrate that the Root Mean square(RMS) of a spot radius is less than 10 μrad in the working wavelength(0.85 μm, 1.064 μm, 1.55 μm), which implements astigmatism correction and obtains a good diffraction-limited quality in a wide spectral region and a high magnification. These results prove the feasibility of the optical design method proposed.