开展了基于伪随机码调制和光子计数的1550 nm光纤激光测距技术研究，研制了一套测试实验系统。为了克服常规InGaAs单光子探测器由于抑制后脉冲而导致的探测速率低的问题，系统采用离散放大光电探测器作为单光子探测器件，单光子探测速率可达100 MHz。在室温，偏置电压53 V，伪随机码序列长度81.91 μs时，系统探测灵敏度可达-83.6 dBm。在不同信号功率及伪随机码序列长度情况下，对系统性能进行了测试。在伪随机码序列长度163.83 μs，信号平均功率-78.6 dBm时，系统测距精度可达12.7 cm。根据实验结果，推算出一套星载条件下的系统参数。

A 1550 nm fiber laser ranging experiment system combining pseudorandom modulation technique and single photon counting method is developed. In order to overcome the low detection rate problems of ordinary InGaAs single photon detectors due to restraining after pulses, a discrete amplification photo detector is used as the single photon detector with a counting rate of 100 MHz in this system. A sensitivity of -83.6 dBm is achieved under room temperature with the detector’s biasing voltage of 53 V and the pseudorandom serial length of 81.91 μs. The system performance is tested under different signal powers and pseudorandom serial lengths. A range accuracy of 12.7 cm is obtained with -78.6 dBm signal average power and 163.83 μs pseudorandom serial length. The system parameters of a spaceborne laser altimeter with this technique are proposed according to the experimental results.