OCS Study MMS 95 - Data Center

2 .4.5 trial of the Laser Line Scan SystemAt present there are two means for sea-floor imaging:seismic and optical.Seismic imaging, such as side-scan sonar or active sonar, is distinctly limited inresolution .Optical imaging, such as underwater photography, has long beenlimited in scope because of backscatter.The Laser Line Scan System (LLSS) is astate-of-the-art optical imaging system that overcomes the back-scatter problemsplaguing underwater photography .Very recent design improvements byWestinghouse Electric Corp ., Underwater Laser Systems have produced a newLLSS, Model SM2000S, that reduced power requirements to under 200 watt andreduced size and weight by roughly half.This improvement makes this LLSS apotential tool for much of the research submersible fleet including ROV's and towedfish, but as yet, the submarine user community has not undertaken any detailedscientific or engineering tasks with the system .In its current configuration, theLLSS provides high-resolution pictures of the seafloor along swaths up to 40 mwide .Despite the promise of this technology, it was unclear whether it could beused to image chemosynthetic fauna in adequate detail .A modification to the Study program was made to facilitate a trial with alaser system over Bush Hill . In this trial, the ART laser system, operated by SAIC,diverted from another mission and spent 12 hr surveying the GC 184 study site .This laser system was deployed in a towed fish by the RN Gyre . The laser producedexcellent images in shallow water, but was severely limited by tow-fish stability indeeper waters . The results over Bush Hill were, therefore, disappointing in terms ofproviding a detailed map of the community. The effort did produce several quitesatisfactory images of tube worm clusters and bacterial mats (Figure 2 .3) . Thisdemonstrates that the technique can work, provided the stability problem is solved .2-20