Display of the underwater sound wavefront using the theory of holographic interference

Abstract

Using the theory of holographic interference and the variable properties of the refractive index of water that has been disturbed by wave motion, a method has been developed where two holograms of the underwater acoustic field are photographed successively on one film plate, before and after the introduction of a wave, which could range in frequency from subsonic to supersonic. A He–Ne laser beam is used to illuminate the film plate, and the image of the wavefront is reconstructed. This new method helps to remove the difficulty underwater acoustic engineers have frequently encountered when observing the scene of an underwater wave.