A Solid Plate Acoustical Viewer for Underwater Diving
Underwater viewing is fraught with problems, as anyone who has ever attempted to do so with the unaided eye or optical instruments well knows. The problems are caused by the behavior of light in the water. Light is effected by three phenomena: refraction, absorption, and scattering. Figure I illustrates causes, effects, remedies, limitations, and solutions for these phenomena. One can see the importance of going to a method that is not light dependent such as acoustics. At the present time, with the exception of a head mounted sonar system under development in Panama City,1 the diver, in optically opaque water, has nothing but the “feel and pray“ method of “seeing“; this is neither appealing nor secure. Several types of acoustical imaging systems have been considered or used in underwater viewing.
KeywordsAcoustic Wave Spatial Filter Grazing Angle Flexural Wave Solid Plate
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