Digital transform processing of carrier fringe patterns from speckle-shearing interferometry

The Fourier transform (FT) and the wavelet transform (WT) methods are used to process the fringe carrier pattern resulting from speckle-shearing intef erometry, in which the carrier frequency is modulated by deformation of a b ending plate. Both the amount and the sign of the first derivative of the o ut-of-plane displacement can be obtained by these two transform techniques in the whole field. Phase distributions of the deflection slope are compare d, which shows the wavelet analysis gives a better solution with noise redu ction and without deficiency of filter window choice as for that in the Fou rier transform. Meanwhile, the phase values in the path along the maximum W T amplitudes give a direct map of the second derivative patterns of the def lection, which presents the same image as that given by the shearing subtra ction of the phase patterns from the inverse Fourier transformation but avo ids the processing of unwrapping for the phase reconstruction.