RANGE-GATED UNDERWATER LASER IMAGING-SYSTEM

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