An USV-based laser fluorosensor for oil spill detection

Abstract

Unmanned surface vehicle (USV) as a new platform has obvious advantages in the marine environmental monitoring. For the requirement of oil spill detection at the sea area of oil spills occur frequently, such as coastal ports, an USV-based laser fluorosensor was developed in our laboratory. In this paper, the overall scheme of USV-based laser fluorosensor system has been proposed, and it consists of shore-based terminal and laser fluorosensor. The laser fluorosensor system has been designed in detail. The axis of the transmitter and receiver in the system are coincident. A micro-pulse nitrogen laser and an ICCD are used as the excitation source and detector respectively. The laser and ICCD are both working at external trigger mode, and a delay generator outputs two TTL signals with fixed delay time to accomplish the time sequence control of the laser and ICCD camera, hence the range-gated detection of the system. The system performance has been tested both in the laboratory and field. The obtained results suggest that the optimal gate pulse delay and gate width of range-gated detection are 112∼113ns and 10ns respectively under the condition of 5 meters detection range. The stability of the system has also been tested by repeated measurements, and the relative standard deviation is determined to be 3.47 %. The feasibility of applying the system to the field detection has also been verified in this work.