Capability assessment of airborne lidar for underwater target detection

Oceanic lidar shows significant potential for efficient and accurate bathymetric measurements at both day and night. However, its performance is constrained by the receiver field of view (FOV) and seawater optical properties, due to signal attenuation, background noise, and beam broadening. Quantitative analyses remain limited, owing to the complex geometric interactions between targets and the laser footprint. This study simulates return signals of six typical targets with varying sizes and shapes under different water conditions to systematically evaluate the effects of FOV, target size, target shape, and chlorophyll concentration on lidar detection performance. Results indicate that larger targets and lower chlorophyll concentrations yield greater maximum detection depths, while increasing the FOV produces a non-monotonic effect. The influence of target shape is minimal when the target is centered on the laser footprint. In oligotrophic, mesotrophic, and eutrophic waters, the maximum detection depths of the six targets range from 72.0∼196.2<i>m</i>, 21.5∼96.5<i>m</i>, and 14.9∼35.9<i>m</i>, with corresponding maximum detection errors of 0.08∼1.09<i>m</i>, 0.09∼2.50<i>m</i>, and 0.11∼2.67<i>m</i>. These findings provide quantitative guidance for system parameter design, offering a theoretical basis for effective airborne lidar target detection in real water environments.