小面阵块扫描激光成像系统实验研究

Experimental Research on Small Scale Risley Prism Scanning Imaging Laser Radar System

阵列成像激光雷达是激光雷达的发展方向,但受到阵列探测器和激光功率的限制,无法实现远距离的高分辨力成像。基于小面阵的块扫描激光雷达兼顾了阵列成像激光雷达的高分辨力和扫描激光雷达的远距离,成为现阶段激光雷达领域的研究热点。采用5×5的阵列雪崩光电二极管(APD)为敏感元,设计了25路并行的放大器,实现了200MHz的带宽和40dB的增益;整形电路输出信号抖动小于2ns,25路阵列计时器时钟频率达到了200MHz。利用上述器件配合高重频固体激光器和双光楔扫描器实现了小面阵块扫描激光雷达的原理实验系统,并利用该系统进行了室内距离成像实验。实验结果表明,该系统能够实现0.8m的测距精度,3°×3°的成像视场角和128pixel×128pixel的图像分辨率。根据所获得的实验结果,对于影响块扫描激光雷达成像精度的因素进行了分析。

Laser radar development tends to focus on array imaging laser radars. Due to the restriction of array detectors and laser power, it is hard to realize imaging with high resolution in distant range. Risley prism scanning imaging laser radars based on small scale array, possessing both the advantages of high resolving power in array imaging laser radar and imaging in distance in scanning laser radar, have drawn much attention in laser radar researches. A small scale array Risley prism scanning imaging laser radar system is constructed with a high frequency solid laser transmitter and a double optical prism scanner for theoretical experiments. The system adopts a 5 X 5 array detector as the sensitive unit and designs a 25-channel parallel amplifier. The bandwidth of 200 MHz and 40 dB gain are achieved with the plastic circuit output signal jitter being less than 2 ns. The frequency of the 25-channel array timer achieves 200 MHz. These realize the small plane array block scanning laser radar principle experiment system. With the system, an indoor imaging experiment is presented. The results show that the ranging accuracy of the system reaches 0.8 m with a 3; X 3; viewing angle and a 128 pixel ; 128 pixel image resolution. It analyzes the factors to influence the accuracy of block scanning imaging laser radar system according to the experimental results. The results show that the beams pointing accuracy, the bandwidth and timing accuracy of the scanner probes and processing circuit have the primary impacts on restriction of distant imaging quality.