<title>Results of the final tank test of the LLNL/NAVSEA synchronous-scanning underwater laser imaging system</title>

Abstract

The design and construction of a synchronous-scanning underwater imaging system capable of rapid two-dimensional scanning is described. The imager employs a 7 W all-lines argon ion laser in conjunction with a galvanometrically driven raster scanner and an image-dissector tube receiver. The imager is capable of directly generating real-time RS-170 video imagery. The results of in-water test of the imaging system demonstrate operating ranges of up to 4 attenuation lengths (AL) when running at real-time frame rates, ranges of 5.1 - 5.5 AL when operating with an 8-frame running average, and ranges of 6.3 AL when using a 128-frame running average. Future frame averaging requirements are expected to be relaxed, due to improvements in the detector preamplifier. The system performance was compared with that of several floodlight/silicon intensified target (SIT) television camera configurations, which produced a maximum imaging range of about 2.6 AL. Also, an imaging configuration that used the raster-scanned beam of the laser as an illumination source for the SIT camera was tested. That system had an ultimate range of about 4 AL.