Abstract:

Underwater three-dimensional (3D) imaging light detection and ranging (LiDAR) systems have the potential for accurately detecting underwater targets and mapping the seabed terrain, thus facilitating the development and utilization of marine resources. However, most existing underwater 3D imaging LiDAR systems suffer from large size and high power consumption, making them unsuitable for the operational requirements of underwater tasks. To overcome these issues, this study proposes a compact solution based on photon-counting technology that integrates single-point ranging with two-dimensional scanning to achieve 3D imaging. A compact underwater photon-counting 3D imaging LiDAR system was developed by optimizing optical and mechanical design, resulting in a device with a diameter of 165 mm and a length of 340 mm, considerably improving portability and underwater adaptability. A dual-axis synchronous scanning control method was implemented based on FPGA to achieve a scanning accuracy at the nanosecond level, ensuring precise alignment between the emitted pulse and measured target point. Laboratory water tank experiments revealed that the system has a detection capability exceeding 3.1 attenuation lengths. Furthermore, this system was used for underwater 3D imaging of a thruster model that validates its centimeter-level ranging accuracy. Owing to its strong compatibility, this system can be integrated into various underwater mobile platforms and holds strong potential for applications such as seabed topographic mapping, underwater cultural heritage detection, and underwater target identification.

Key words: underwater detection, three-dimensional imaging, LiDAR, miniaturization