Recent Developments In Underwater Laser Scanning Systems

A prototype underwater laser scanner imaging system has been built and tested in a laboratory test tank. Simultaneous tests were conducted with two state of the art commercial underwater television cameras to quantify the performance of the prototype scanner relative to conventional imaging systems. Tests were conducted with the clarity of the water adjusted to match the clarity of clear deep ocean water, beam attenuation coefficient c = 0.10/meter, and the clarity of typical coastal water, c = 0.39/meter. The scanner system used a 40 milliwatt (combined 488 nanometer and 514.5 nanometer) Argon ion laser as the light source and a 2 inch diameter photo multiplier tube (PMT) as the detector. The PMT had an unrestricted field view. No scan synchronization, range gating, or other advanced techniques were used.