对于任何通信系统而言,天线能否正确发射和接收有效信号是人们最为关心的问题.对于点对点的激光通信系统而言,由于激光与电波迥然不同的特点,在天线系统的设计上更需严格要求.在空间光通信系统中,光学天线是一个物镜系统,通过折射、反射和折射-反射光学系统实现,目前应用比较广泛的是牛顿系统、格林系统以及卡塞格伦系统.讨论了卡塞格伦天线系统,该系统的结构(双反射式)决定了存在遮挡比造成光能量浪费的潜在问题,也就是所谓的渐晕现象.另一个问题是像差,也就是卡塞格伦天线系统要获得良好的像质必须以牺牲视场为代价.基于这两点提出了减小渐晕的几种新方案,并从减小像差上进行了理论分析.

Antenna, which whether transmits or receives correct signal or not is our main care and our direction, is an important part in any communication systems. Because of the characteristics of laser different from radio, the antenna system of point-to-point laser communication system must be designed strictly. Newton system, Green system and Cassegrain system are accepted commonly in optical antenna systems as field lens which include refraction system, inflection system and refraction-and-inflection system. In this paper, Cassegrain antenna is discussed. However, the potential problem of sheltering ratio in Cassegrain system leads to a loss of effective power of the optical system so called vignette phenomena. The other is related to optical aberration, because Cassegrain antenna sacrifices sight field for perfect image. We put forward some new solution and analyze theoretically how to reduce aberration based on the two considerations.