分析了以卡塞格林（卡式）望远系统作为光学天线时, 大气激光通信捕获、对准和跟踪系统中四象限光电探测器光敏面上环形光斑位置检测的误差问题。基于光斑中心遮挡与死区感应光能量的等同效应, 理论推导了入射环形光斑偏移量与光斑中心坐标、探测器死区宽度和环形光斑内外圆半径之间关系的数学模型。数值仿真和实验结果表明: 与完整高斯光斑相比, 环形光斑的探测线性范围较小, 检测灵敏度较低。根据实验条件选择合适的卡式光学天线或光斑半径, 使遮光比为30%时探测器的探测线性范围最大, 不会出现非线性误差。所提环形光斑误差补偿算法克服了光斑中心遮挡带来的位置检测误差, 探测器探测精度可达0.0015 mm。

When a Cassegrain telescope system is taken as optical antenna, the error of annular facula position detection on the photosensitive surface of four-quadrant photoelectric detector in acquisition, pointing and tracking system for atmospheric laser communication is analyzed. Based on the equivalent effects of the facula center shelter and dead zone induction light energy, mathematical models of relationships among facula center coordinate, dead zone width of detector, inner and outer circle radii of annular facula and incident annular facula offset are theoretically deduced. Numerical simulation and experimental results show that the detection linear range of annular spot is smaller than that of complete Gauss facula, and the detection sensitivity is lower. The appropriate Cassegrain optical antenna and facula radius are selected according to the experimental conditions, so that the detection linear range of detector is the largest when the shading ratio is 30%, and nonlinear error will not occur. An annular facula error compensation algorithm is proposed to overcome the position detection error caused by the facula center shelter, and the detection accuracy of the detector can reach 0.0015 mm.