光电探测器是影响激光测高仪探测性能的重要器件。为了使探测器性能保持最佳状态，采用了近似算法进行分析。该算法使用近似分布函数来模拟探测器的输出，推导出虚警率与阈值门限和倍增因子三者之间的函数关系，找出虚警率、阈值和增益之间的最佳结合点。实验表明，根据该方法设计的激光测高仪探测器接收电路，可使探测概率和回波信噪比有显著提高。这一结果对激光测高仪目标特性的回波分析和地形地貌3维轮廓重建有很大帮助。

The photo detector is an important device,which affects the detection capability in laser altimeters. In order to maintain the detector's best performance,an approximation algorithm was developed in which the approximate distribution function was used to simulate the output of the detector,so that the relationship among false detect probability,threshold and detector's gain was obtained,and the best combination of the three parameters were found. The experiment results indicate that the detector's receiver circuit based on the approximation algorithm owns apparent improvement in detect probability and echo signal-to-noise.This result is benefit for analyzing the object characteristics of laser altimeter and rebuilding the three-dimension contour of terrain and physiognomy.