Early Detection of Partially Emerged Large Scale Marine Debris Based on Laser Pulses

The Large Scale Marine Debris (LSMD), or drifting objects, pose a serious threat to navigation safety, be they containers, dispersed cargo, large trunks, marine animals, small boats or other large-sized scattered materials. Specifically, in the case of containers, it is estimated that over 10,000 of the approximately 100 million that cross seas and oceans are dispersed each year. Several reported incidents have caused significant dents on ships hulls and in some cases, breaches leading to the sinking of vessels. In many cases, on-board devices such as radar or sonar are able to effectively detect completely emerged or submerged obstacles, respectively, but the presence of partially emerged floating bodies is more difficult to detect due to the significant disturbance introduced by the wave motion. In this article, we present a method based on the photothermal effect which allows for the detection of floating objects even at great distances (500m) through the collimated light of a laser, enabling turning operations for even large vessels and avoiding collision with the obstacle.