Underwater 3D measurement using sheet of light system with multi-layer refractive interface

•A high-precision underwater three-dimensional measurement sheet of light system with multi-layer refractive interface was designed.•A method for extracting the center of laser lines suitable for special underwater scenarios was proposed.•A correction method for effectively alleviating the refraction of underwater multi-medium has been proposed based on ray tracing and pso. Underwater measurements present substantial challenges, including refraction, scattering, and absorption. However, with the ongoing advancements in underwater optical measurement technology, active optical measurement techniques based on a sheet of light have increasingly become a focal point of research. This paper presents the development of a reflective underwater sheet of light system with a multi-layer refractive interface. It also proposes an enhanced refraction correction method that utilizes the ray tracing method and particle swarm optimization (PSO). By establishing an objective constraint function using calibration images, it estimates refractive correction parameters through iterative optimization. The static and dynamic measurement experiments conducted on simulated nuclear fuel assembly (NFA) demonstrate the effectiveness of the proposed refraction correction method. These measurements validate the efficacy of the underwater sheet of light system and offer a refraction correction method for the multi-layer refractive interface.