基于伪随机码相位调制和相干探测的激光测距技术研究

Research on Laser Ranging Technology Based on Pseudo-Random Code Phase Modulation and Coherent Detection

为实现远距离高精度激光测距,提出了一种联合利用伪随机码相位调制和相干探测技术的激光测距方法,并搭建实验验证平台对自由空间目标进行了测试。当激光出射功率为2.0mW、参考光功率为117.8μW、调制速率为100 MHz、单周期内伪随机码序列长度为81.9μs、望远镜接收口径为2cm时,该系统可对8m处的自由空间目标实现11.8cm的测距精度。实验证实了该套技术方案的可行性。将此实验结果反推至星载条件,并与GLAS(Geoscience Laser Altimeter System)系统参数进行对比发现,该系统工作在低峰值功率、长脉冲宽度状态下,故可实现高重复频率探测。

In order to realize high precision long-distance laser ranging, a laser ranging method based on the techniques of pseudo-random code （PRC） phase modulation and coherent detection is proposed. An experiment system for the free space target detection is set up. When laser outputs power, local oscillator power, modulation rate, PRC sequence length in a single cycle and telescope aperture are respectively 2.0 mW, 117.8 p.W, 100 MHz, 81.9 t^s and 2 cm, the system can achieve a ranging accuracy of 11.8 cm for the free space target located in about 8 m far away. The experimental results prove the feasibility of the proposed method. The experimental results are back-propelled to the spaceborne conditions and compared with the GLAS （Geoscience Laser Altimeter System） system parameters. The comparison results show that the system operates under lower peak power and longer pulse width conditions, so high-frequency detection can be achieved.