不同鉴别阈值条件下SiPM光子计数激光雷达探测模型及性能分析

The photon detection mode and performance analysis of SiPM photon counting Lidar under different discrimination thresholds

硅光电倍增管(Silicon Photomultiplier,SiPM)具有极高的探测灵敏度和响应速度,且在多光子条件下具有较高的动态范围以及线性响应的特性,在光子计数激光雷达应用中有独特的优势。然而,由于SiPM多像元、单时间通道的工作模式,其输出电压信号相较于其他单光子探测器更大概率出现脉冲堆叠现象,不同鉴别阈值条件下的SiPM探测过程更为复杂。针对该问题,本文建立了SiPM光子事件响应模型,以此为基础分析了由脉冲堆叠引发的屏蔽效应和触发效应两种特殊情况的时域分布,最终建立了SiPM半解析的探测概率与虚警概率模型。同时,搭建了基于SiPM探测器的光子计数雷达系统,通过观察实测输出电压波形以及光子点云分布与理论模型相符(R^(2)>0.95)。通过查全率与查准率对不同鉴别阈值的SiPM光子点云分布进行定量评价,并给出最优鉴别阈值区间,这对基于SiPM的光子计数激光雷达系统硬件参数的优化设计以及探测性能的定量分析具有重要的指导意义。

Silicon photomultiplier(SiPM)is a silicon array structure based on the Geiger mode avalanche photodiode.It not only has extremely high photon counting sensitivity and response speed,but also has the characteristics of high dynamic range and linear response under the multi-photon condition,which makes it have unique advantages in the application of photon counting LIDAR.However,due to the multi-pixel,single-time channel working mode of SiPM,its output voltage has a greater probability of pulse pile up compared with other single-photon detectors.Therefore,the detection process of SiPM under different discrimination thresholds is more complicated.To solve this problem,a SiPM photon event response model is established in this paper.Based on this,the time-domain distributions of the shielding effect and the triggering effect caused by pulse pile up are discussed.Finally,the semi-analytic detection probability and false alarm probability models of SiPM are established.At the same time,a photon counting Lidar system based on SiPM detector is built,and the theoretical model is verified by observing that the measured output voltage waveform and point cloud distribution are consistent with the theoretical model(R^(2)>0.95).Furthermore,the distribution of SiPM photon point cloud with different discrimination thresholds is quantitatively evaluated by the recall and precision ratio,and the optimal discrimination threshold interval is given,which has important guiding significance for the design and theoretical analysis of photon counting Lidar system based on SiPM.