Full-waveform distortion characteristics of photon counting Lidar at different dead-time

Abstract

The Photon Counting Lidar is widely used in the detection of far and small targets because of high sensitivity. When the laser spot covers the target, only obtaining a position and reflectivity information from each pixel can no longer meet the needs of target detection and recognition. The intensity distribution of pulse laser echo is modulated by the target. Due to the existence of dead-time, the first photon bias occurs, which causes waveform distortion between photon waveform and pulse laser echo. So studying the waveform distortion characteristics with various parameters is of great significance to acquire the target information in a single pixel. In this paper, a universal iterative detection probability calculation method is improved to quickly reconstruct the photon waveform, and three parameters of correlation distance, ratio of pulse peak, and relative time difference are defined to describe the details of the waveform distortion. The waveform distortion is analyzed at typical dead-time with various parameters, such as single-pulse photon number, pulse width, noise, and target position. The results show that when the dead-time is shorter than the time interval of targets or single-pulse photon number is less than 0.1, the correlation distance is less 5% and the waveform distortion could be negligible, while the others couldn’t. When the count of noise is less than 107/s, or the pulse width is 5% of the interval of targets, or the duration of the target position is slightly longer than the time interval of targets, the waveform distortion is minimal.