RANGE-GATED UNDERWATER LASER IMAGING-SYSTEM

A careful analysis of a scattering and absorption database of the waters off the coasts of Canada shows that a laser-assisted camera system will have a significantly improved viewing performance over conventional systems. The laser underwater camera image enhancer system is a range-gated laser system that can be mounted on a remotely operated vehicle. The system uses a 2-kHz diode-pumped frequency-doubled Nd:YAG laser as an illumination source. The light is collected by a 10-cm-diam zoom lens. The detector is a gated image intensifier with a 7-ns gate and a gain that is continuously variable from 500 to 1,000,000. The system has been tested in a water tank facility at Defence Research Establishment Valcartier and has been mounted on the HYSUB 5000 remotely operated vehicle for sea trials. In the strongly scattering waters typical of harbor approaches, this system has a range of from three to five times that of a conventional camera with floodlights.