Research on Acoustical Scattering, Diffraction Catastrophes, Optics of Bubbles, Photoacoustics, and Acoustical Phase Conjugation

摘要

The research summarized concerns several aspects of the propagation and scattering of acoustical and optical waves. The topics discussed are: A. Acoustical scattering theory and experiments for elastic objects in water (the coupling of sound with surface waves on fluid loaded elastic objects as described by a generalization of GTD, confirmation from measurements of focused backscattering due to Lamb waves on a spherical shell); B. Light scattering from real bubbles and microbubbles in water (the unfolded glory or backscattering pattern of an oblate bubble in water, observation of Brewster angle scattering of polarized light and the effects of adsorbed films which may coat the bubble); C. Production of sound by a drop or bubble in water illuminated by modulated laser light and the optical levitation of bubbles; D. Acoustical and optical diffraction catastrophes (theory and optical simulation of transverse cusps, experiments with acoustical transverse cusps produced by reflection from smooth surfaces and the merging of echoes at caustics, the wavefield in a hyperbolic umbilic focal section, applications to the theory of shock wave focusing); E. Acoustical phase conjugation (theory of the focal-point shift for the reversed wave resulting from three-wave mixing in a bubble layer, experimental evidence for the existence of such a wave).