Compact, large aperture 2D deflection optic for LiDAR underwater applications

An increasing number of underwater structures require regular, highly accurate inspections to maintain a safe and sustainable operation. Conventional sonar systems often lack the necessary resolution and precision, and camera-based systems are easily disturbed by turbid water. A technology which can bridge this gap is pulsed time-of-flight ranging. It provides higher resolution and precision compared to acoustic methods and tolerates turbid water. In this paper, we present a specialized underwater LiDAR (light detection and ranging) system which is capable of recording camera-like planar scenes using a two-dimensional beam-deflection unit. This is achieved using a combination of two rotating wedge-prisms mounted into custom-build motor modules which allows configurable linear, circular, and planar scan-patterns. Its compact design, paired with a large 33° deflection angle and 45 mm clear aperture makes it ideal for challenging underwater conditions.