Spatial and temporal domain filtering for underwater lidar

Combined spatial and temporal processing techniques are presented to enhance optical ranging in underwater environments. The performance of underwater light detection and ranging (lidar) is often limited by scattering. Previous work has demonstrated that both hybrid lidar-radar, which temporally modulates the amplitude of light, and optical spatial coherence filtering, which spatially modulates the phase of light, have independently reduced the effects of scattering, improving performance. The combined performance of the processing methods is investigated, and experimental results demonstrate that the combined filtering improves the performance of underwater lidar systems beyond what either method provides independently.