Underwater acoustic imaging: image due to a specular reflector in the geometrical-acoustics limit.

Abstract

In underwater acoustic imaging, used to produce high-quality images in turbid waters, a specular reflector can produce a 'pseudoimage' of the receiving array at the reflecting surface. Based on the 'geometrical approximation' (similar to geometrical acoustics), formulae are derived for the size and shape of the pseudoimage for both flat and curved reflectors. For curved reflectors, described by two principal radii of curvature, the formulae assume also the 'large-range approximation'. The formulae enable radii of curvature to be determined from an image. Also discussed briefly are possible extensions and the role of non-geometrical effects.