Fringe Localization in Acoustical Holographic Interferometry

Abstract

We study the localization of fringes in acoustical double exposure, multiple-beams, time-averaged and linearized subfringe holographic interferometry. Both scanning and liquid surface methods are used. The distance of the localization fringes to the object surface is derived. It can be used to study the surface microstructure. Results from scanning method differ from the optical cases by showing the property of sound wave as long wavelength and can be detected linearly. We also apply the correlation function method to derive the intensity of acoustical holographic interference fringes for the scanning method. Results from liquid surface method are the same as that from optical holography because we do not consider the time varying properties of the acoustical fields. We derive the acoustical transfer function for the liquid surface method which is equivalent to the characteris- fringe function in optical holography. We finally discuss the applications of acoustical holographic interferometry.