100 km远距离测距的激光雷达，由于作用距离远，多采用低重复频率、高能量激光器配合大口径望远镜实现远程激光测距，导致系统存在体积大、重量大、功耗高等缺点。基于光子计数技术的激光测距雷达具有灵敏度高的特点，有效降低了系统的激光能量和望远镜的接收口径，降低了系统的体积、重量和功耗。设计了一种应用于远距离小目标探测的测距激光雷达，采用盖格模式的雪崩光电二极管实现光子计数，实现了系统的小型化。详细介绍了该系统的设计原理、组成部分和实验结果。实验结果表明，在双程大气透射率为0.25的大气环境下，对于有效反射面积为6 m2、反射率为0.1的小目标，该系统的最远测距能力达到100 km，距离分辨率为6 m。

For the application of laser detection over a long distance of 100 km, to achieve the long-distance detection, the system mostly uses low repetition frequency, high pulse energy laser and large diameter telescope, which leads the shortcomings of large volume, heavy weight and high power consumption. The lidar based on photon counting technology has the characteristic of high sensitivity. It greatly reduces the laser energy and receiving telescope aperture of the system. The volume, weight and power consumption of the system are reduced. A kind of laser ranging lidar applied in high-altitude remote detection of small target is designed, which adopts Geiger-mode avalanche photo diode achieving photon counting, and realizes the miniaturization of the system. The system design principle, component, and the experiment result are introduced in detail. The results show that when the round-trip atmospheric transmittance is 0.25, the maximum detection range can reach 100 km for the small target with 6 m2 effective reflection area and 0.1 reflectivity, and the range resolution is 6 m.