DIGITAL-TECHNIQUES FOR STRAIN-MEASUREMENT USING ELECTROOPTIC HOLOGRAPHY

Some new approaches to the digital analysis of the fringes obtained in electro-optic holography are presented. The technique of phase stepping supplemented by Fourier filtering, for the elimination of noise in wrapped-phase maps, is discussed first. The problem introduced by discontinuities at the object boundary and a fringe extrapolation technique to overcome this problem are discussed next. Finally, a technique to compute the phase derivatives directly from the wrapped-phase map is outlined.