Optical Backscatter Calculations for an Underwater Range-Gated Imaging System

To obtain the resolution of a range gated imaging system in the laboratory, the optical backscatter of seawater arriving at a detector is calculated. Backscatter optical geometry and the related parameters for underwater range gated imaging system with typical pulsed laser illumination are given and analyzed. Based on the radiation transmition theory, a model of optical backscatter of the underwater range gated imaging system is given. The theoretical calculations are programmed, and figures of overlap coefficient and optical backscatter plotted based on typical system parameters. The figures obtained show that the backscatter radiant flux arriving at the detector increase rapidly with time, and then declined swiftly after reaching the maximum. The backscatter radiant flux of 5 ns laser pulse has centralized distribution within a 20 ns interval.