考虑脉冲高度分布(PHD)的光电倍增管光子探测模型

The photon detection mode of photomultiplier tubes considering the pulse height distribution

光电倍增管(Photomultiplier Tubes,PMT)具有光子级别的灵敏度,而且没有物理意义上的死区时间,在光子计数雷达应用中有独有的优势,但PMT响应单光子输出脉冲高度呈高斯随机分布,且不同脉冲之间还有可能产生堆叠,传统的单光子模型不能准确描述PMT的光子探测过程。针对PMT输出脉冲高度随机分布,脉冲堆叠现象和光子事件鉴别阈值的设置对光子事件探测概率的影响提出了一个新的PMT光子探测模型,并根据实际应用场景进行了简化,通过蒙特卡洛仿真验证了简化模型的适用性。搭建了光子计数雷达系统,通过和盖革模式APD进行实验对比,发现PMT光子探测模型虽然有略微的探测概率损失,但在测距应用中具有更小行走误差和更高测距精确度。实验也证明了新模型相比于传统单光子探测模型更符合PMT的光子事件探测概率分布,新模型对基于PMT光子计数雷达的系统设计和理论分析具有重要的指导意义。

Photomultiplier tubes(PMT)have unique advantages in photon-counting LIDAR applications due to its photon-level sensitivity and lack of photon detection dead time.However,the output pulse height of PMT responds to the single photon follows the Gaussian random distribution,and there may produce pile up between different pulses.When using the fixed threshold method to identify the photo-events,the traditional single photon model can not accurately describe the photon detection process of PMT.By analyzing the influence of PMT output pulse height distribution,pulse pile up and the amplitude of photo-event discrimination threshold on the photo-events detection probability,a new PMT photon detection theoretical model was built,and the mode was simplified according to the practical application scene.The applicability of the simplified model was verified by Monte Carlo simulation.The correlation characteristics of the new model in photon-counting ranging are analyzed.A photon-counting LIDAR system is built,compared with Geiger mode APD,the PMT photon detection model has a slight loss of photon detection probability,but it has a smaller ranging walking error and higher ranging accuracy in photon-counting ranging applications.The experiment also proves that the new model is more consistent with the photo-event detection probability of PMT than the traditional single photon detection model.The new model has important guiding significance for the system design and theoretical analysis of PMT photon-counting LIDAR.