为了评估大气湍流、通信平台振动和校装误差等因素引起的光斑偏移现象对空间激光通信系统通信性能的影响, 理论计算和实验测量了空间激光通信系统中APD光电转换后的电信号幅值随会聚信号光斑和光电探测器光敏面之间的横向位移、以及探测平面和透镜焦平面之间的离焦量的变化关系, 同时给出了系统误码率、信噪比、抖动与相偏移量之间的实测曲线。结果表明, 空间激光通信系统性能随横向位移以及离焦量的增加而急剧恶化, 且横向位移的影响远大于前后离焦的影响。在实验参数条件下, 当系统误码率从10－10变化到10－5时, 允许系统横向位移和离焦量分别为0.03和1 mm。

In order to predict and estimate the effects of the atmospheric turbulence, the vibration of terminals and misalignment on space laser communication, the curves of the amplitued of detected signals changed with lateral offset (between the central of focused beam and the central of photodetector in detecting plane, Δxa and Δya) and defocus (between the detecting plane and the focal plane, Δf) are calculated in simulation and measured in experiment, and the curves of BER, SNR and Jitter of the detecetd signals changed with lateral offset and defocus are measured at the same time. The results show that the properties of space laser communication systems would be deteriorated significantly as the lateral offset and defocus increase, and the properties are deteriorated severely by lateral offset than by defocus. The maximum permitted disfocus and lateral offset are 1 mm and 0.03 mm with the experimental parameters when BER of communication decreases from 10－10 to 10－5．