Signal-to-noise ratio and spatial resolution characteristics of underwater time-gated SPAD array imaging systems

This study establishes comprehensive system signal-to-noise ratio and spatial resolution models for underwater time-gated (TG) imaging systems using single-photon avalanche diode (SPAD) arrays. Effects of water attenuation, target distance, and system parameters on detection range and spatial resolution are investigated, and corresponding optimization strategies are proposed. A complete underwater time-gated SPAD (TG-SPAD) array imaging system is constructed using a SPAD512S detector and experimentally validated, and a signal-to-noise ratio threshold of 2.5 is proposed for system performance evaluation. Results confirm high precision, with an average relative error of 2.90% between theoretical predictions and experimental measurements. This study offers theoretical guidance and technical support for the optimal design, evaluation, and applications of underwater TG-SPAD array imaging systems.