激光测距多光子分立时刻的反卷积解算方法

Multi-Photon Time-of-Arrival Resolution Enhancement by Deconvolution in Laser Ranging

针对多像素光子计数器（MPPC）各像素雪崩电流并联输出、存在光子间隔过小导致脉冲变形而无法分辨光子时刻的问题,结合光子分布与输出脉冲波形,通过数学反卷积,获得了激光测距接收端各探测光子分立时刻的解析解,从而实现了观测量倍增,有助于有效信号的分辨及提取。该方法将单脉冲响应函数近似为高斯形式,分析了MPPC时间抖动的影响,研究了在时间抖动为50～250 ps范围内,从三个入射光子输出的变形脉冲中解算出的分立时刻,得到分立时刻随光子间隔的统计分布图和峰谷分辨度随光子时间间隔、MPPC时间抖动的变化关系。并验证了在1 s观测时间内,千赫兹激光测距系统经反卷积解算前后观测量对比效果。分析结果表明,当统计分布中峰谷分辨度大于10时,各光子分立时刻可以有效分辨,该方法的时间分辨力达到0.2～0.7 ns。

Avalanche photo diodes（APDs） are parallel connected in multi pixel photon counter（MPPC）. The output pulse is distorted when photon arrival time gets closer, and discrete photon arrival time is unable to resolve. With photon distribution and output pulse considered, analytical form of discrete photon arrival time detected in laser ranging is derived with deconvolution from the output pulse. Also, ranging data size is increased, helpful for the recognition of efficient photons from noise. In the algorithm, single pulse response is approximated to Gaussian form, and effects of time jitter on photon discrimination are studied. Consumed the time jitter of pulse response is 50～250 ps, both statistical distribution histogram and the relation of peak-valley contrast, time interval and time jitter are obtained with three photons. Data sizes before and after deconvolution are compared in k Hz laser ranging system during 1 s observation time. Results show discrete time is able to be resolved when peak-valley contrast is above 10 in histogram, and the discrimination time resolution is 0.2～0.7 ns.