为实现对激光通信系统终端的实验室性能检测，需在实验室中采用光学方法模拟空间不同距离的激光传输。根据前置傅里叶变换镜的参数，提取了链路衰减系统的初级设计指标，并根据指标要求巧妙利用了光学放大、变焦系统级联的思想，实现可变距离的空间链路过程模拟；利用ZEMAX 光学软件设计了单级3~10 倍连续变焦的模拟系统，给出了单级放大率和变焦系统之间的曲线。单级系统总长309 mm，结构紧凑，全视场波像差优于0.05 λ ，光线能量集中。通过理论分析，四级级联可实现等效为103~105 km 的传输距离，从而满足大多数激光通信终端的检测要求。

To achieve the laboratory performance test to laser communication system terminal, an optical method to simulate the laser transmission in different distances is required to use in the laboratory. In this paper, the primary design index of a link attenuation system is extracted according to the parameters of the front Fourier- transform lens. This paper cleverly makes use of the thoughts of optical enlargement and cascaded zoom system according to the index. The simulation to space links with variable distances is realized. A simulator system which can realize 3~10 times continuous zooming of a single-stage is designed, optimized by using ZEMAX, and the zoom curve of a single- stage is drawn. The structure of single- stage system with length of 309 mm is compact. The wavefront aberration of the whole field is better than 0.05 λ . The energy of light is concentrated. Through theoretical analysis, four cascaded design can achieve equivalent transmission distance of 103~105 km, so as to satisfy the detection requirements for most of the laser communication terminals.