The Two Dimensional Fourier Transform Method of Holointerferogram Analysis for the Determination of Surface Displacement

Holographic interferometry is a method for analyzing the light scattered off the surface of materials so as to obtain accurate measurement of surface displacements as small as a fraction of the wavelength of light. However the analysis of holointerferograms is hindered by the fact that the holointerferograms themselves do not contain enough information to determine the sign of the phase changes over their area. Various techniques have been proposed and developed to resolve this sign ambiguity, such as the introduction of a carrier fringe pattern, the use of sandwich holograms, the use of a mutual phase shift between two successive holointerferograms and the Fourier transform method. This thesis will attempt to develop the last mentioned technique by applying a two-dimensional fast Fomier transform along with image processing techniques to obtain a quantitative evaluation of the deformation of the surface of an object