Fig 10,1 Western Manne Electronics' (WESMAR) Model SS100 scanning sonar aboard PISCES III. (HYCO) 



Acoustic Imaging — Under Certain conditions 

 underwater visibility by optical means is im- 

 possible owing to turbid conditions (sus- 

 pended material). For such contingencies 

 acoustic devices have been developed which 

 can insonify objects and present an image on 

 a CRT quite analogous to optical viewing. 

 Investigators at Lockheed (7) described a 

 system developed for the DSRV which oper- 

 ates at a frequency of 2.5 megahertz (MHz) 

 and affords a real-time, high-resolution opti- 

 cal display of underwater objects or activi- 

 ties at ranges up to 30 feet. The DSRV's 

 would employ acoustic imaging for mating 

 with or clearing debris from around the 

 hatch of a stricken submarine when optical 



devices were ineffective. However, no results 

 of the system's use in the field are available. 



Visual: 



For short range and detailed knowledge of 

 the external environment the human eye is 

 the most perceptive and trustworthy instru- 

 ment aboard a submersible. The effective- 

 ness of the eye is governed by ambient light 

 level, turbidity and, in the case of artificial 

 lighting, light location. On some vehicles di- 

 rect viewing, i.e., through viewports, is aug- 

 mented by television. Both direct (viewports) 

 and indirect (TV) viewing have their advan- 

 tages and disadvantages, and the factor 

 bearing most heavily on either system's ef- 



470 



