High-flux single-photon LiDAR imaging through obscurants at count rates above pile-up limitations

Light detection and ranging (LiDAR) represents a widely used method to obtain highly detailed three-dimensional maps of the environment. While LiDAR generally benefits from a high-flux operation regime, the use of the time-correlated single-photon counting (TCSPC) technique can be limited by the pile-up phenomenon, which prevents acquisition rates higher than 5% of the laser excitation rate. If higher acquisition rates are used, pile-up can affect the timing data by introducing distortions in the histogram. Here, we analyze and discuss these strong distortion effects induced by pile-up in the specific case when measuring low-reflectivity targets through obscurants, both for single-point measurements and three-dimensional imaging. Furthermore, we demonstrate that it is feasible to overcome the enforced constraint, reaching a count rate of almost 30% (an order of magnitude higher) without notable distortion, even in the presence of complex multi-echo waveforms. This is accomplished through a purely hardware-based solution, by means of a precise matching between the single-photon detector dead time and the laser period. The achieved results pave the way to faster single-photon LiDAR in multiple applications, such as imaging through obscurants, underwater imaging, and hyperspectral and multispectral imaging.