High-Resolution Underwater Single-Photon Imaging With Bessel Beam Illumination

The ability to achieve precise underwater 3D imaging is an urgent need in marine research and development. Yet, due to the strong scattering by the water, the laser beam is easily spread out in the underwater propagation, which hampers the imaging quality with low resolution. In this paper, we demonstrate a single-photon LiDAR with Bessel beam illumination, which central spot shows a stable diameter of about 0.73 mm after propagating 18 m in water. Together with a single-photon detector to sense the weak returning laser echoes, the transverse resolution reaches about a few millimeters at 17.5 m in water. In the experiment, an underwater optical image of 103.1 mm × 192.1 mm with 516 × 97 pixels is reconstructed. The result shows that our single-photon LiDAR with Bessel beam illumination greatly improves the imaging resolution in the long distance underwater sensing.