Zhang Zijing, Wu Long, Zhang Yong, Zhao Yuan
Department of Physics, Harbin Institute of Technology, No. 92, Xidazhi Road, Harbin 150001, China.
Appl Opt. 2013 Jan 10;52(2):274-9. doi: 10.1364/AO.52.000274.
Photon-counting chirped amplitude modulation (PCCAM) ladar employs Geiger mode avalanche photodiode as a detector. After the detector corresponding to the echo signal is reflected from an object or target, the modulation depth (MD) of the detection outputs has some certain loss relative to that of the transmitting signal. The signal-to-noise ratio (SNR) of PCCAM ladar is mainly determined by the MD of detection outputs of the echo signal. There is a proper echo signal intensity that can decrease the MD loss and improve the SNR of the ladar receiver. In this paper, an improved PCCAM ladar system is presented, which employs an echo signal intensity optimization strategy with an iris diaphragm under different signal and noise intensities. The improved system is demonstrated with the background noise of a sunny day and the echo signal intensity from 0.1 to 10 counts/ns. The experimental results show that it can effectively improve the SNR of the ladar receiver compared with the typical PCCAM ladar system.
光子计数啁啾幅度调制（PCCAM）激光雷达采用盖革模式雪崩光电二极管作为探测器。探测器对应的回波信号从物体或目标反射回来后，探测输出的调制深度（MD）相对于发射信号的调制深度会有一定损失。PCCAM激光雷达的信噪比（SNR）主要由回波信号探测输出的MD决定。存在一个合适的回波信号强度，可以降低MD损失并提高激光雷达接收器的SNR。本文提出了一种改进的PCCAM激光雷达系统，该系统在不同信号和噪声强度下采用带光阑的回波信号强度优化策略。在晴天背景噪声和0.1至10计数/纳秒的回波信号强度下对改进后的系统进行了演示。实验结果表明，与典型的PCCAM激光雷达系统相比，它可以有效提高激光雷达接收器的SNR。
