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

In underwater acoustic imaging, which is 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” (which is 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 also assume the “large-range approximation.” The formulae allow radii of curvature to be determined from an image. Also discussed briefly are some possible extensions and the role of nongeometrical effects.