为使星载激光高度计实现高空间分辨率, 提出了一种联合采用伪随机码调制光纤激光器和单光子计数的测距方法。讨论了此方法的实施方案, 推导了此方法用于测高时的信噪比公式。对方案中的激光发射功率、接收望远镜口径对信噪比的影响进行了数值模拟。对系统参数进行分析, 得到了相关参数的关系和优化的参数。结果表明接收望远镜口径为0.8～1 m, 激光出射功率约为10 W, 伪随机码调制宽度为600 μs, 调制速率为1 GHz时, 基于伪随机码调制和单光子计数的星载激光测高计能够使系统信噪比达到10, 距离分辨率达到15 cm。

A method combining pseudorandom modulation of the fiber laser and single-photon counting is proposed to realize a high spatial resolution for the space-borne laser altimeter. The detailed principle of detection is presented, and the equation of the signal-to-noise ratio for the altimeter is given. The relationships between the signal-to-noise ratio with the laser power and the receiving telescope aperture are numerically simulated. The relationships between the parameters and the optimized parameters are obtained after analysis. Results show that the space-borne altimeter can reach the signal-to-noise ratio of 10, and the distance resolution of 15 cm when the receiving telescope aperture is between 0.8 m and 1m, laser power is about 10 W, pseudorandom modulation pulse width is 600 μs, modulation frequency is 1 GHz. This system can meet the requirement of altimetric measurement under the condition of space-borne environment.