Trajectory correction and position error analysis of underwater laser scanning

•An underwater laser scanning trajectory correction model with nonuniform refractive index affecting beam propagation path.•The modified model is effective in detecting range and angle deviation of plane target.•The influence of vehicle attitude angle change on scanning point position error is analyzed and suggestions are given.•Under certain conditions of salinity and incident angle, the correction model accords with the experimental results. To improve the coordinate accuracy of underwater laser scanning point positions, the basic equation of the beam trajectory of the pyramidal polyhedron laser scanning system was deduced, based on the underwater vehicle. The influence of underwater nonuniform refractive index on the beam trajectory was analyzed. A beam trajectory correction model based on the time of flight was established. An experiment was performed to detect the offset positions of light spots under different incident angles and salinities. Compared with scanning results of the uniform refractive index, these results were in good agreement with the correction model. In the process of laser scanning position acquisition underwater, the influence of nonuniform refractive index on spot position cannot be ignored. The correction scheme of scanning point position offered significant reference for obtaining laser scanning point coordinates of underwater.