Submarine lidar for seafloor inspection

Substances released at sea by accident or illegal discharges are characteri zed by a broad range of chemical and physical properties. Moreover, the cha racteristics of coastal waters, e.g. in the German Eight, are highly variab le. Due to this a submersible sensor network for the detection of hazardous substances on the seafloor combining several instruments based on differen t physical and chemical principles has been under development since 1996. I n addition to conventional sensors for seawater analysis and seafloor monit oring such as CTD probes (conductivity, temperature, depth) and video camer as, the system includes several newly developed instruments for the detecti on of dissolved and sunken pollutants. One of these instruments is the submarine lidar, combining a range-gated im aging device and a fluorescence lidar. A q-switched Nd:YAG laser is used as the common light source. Applying the expanded frequency-doubled laser pul se the gated CCD camera is particularly useful for recording images of dama ged containers with chemical cargo where harmful substances might be releas ed into the water column. Tuned to UV emission, the same laser is used for remotely classifying fluorescent substances spreading on the seafloor. The intention of this paper is to present the submarine lidar in detail and to give an overview of its physics and potential applications.