YOUNGS FRINGES ANALYSIS WITH A COMPUTER IMAGE-PROCESSING SYSTEM

A two-dimensional Fourier transform analysis is presented for numerically processing the Young's fringes diffraction pattern from a double-exposure speckle photograph. The fringe spacing and orientation are determined using only one Young's fringes pattern without any other diffraction halo patterns. This algorithm is based on the 2-D FFT of the fringe pattern with 256 x 256 pixels. Therefore, it enables automatic analysis to be performed on specklegram with noisy and poor fringe patterns. The measurement of deformation by the laser speckle method can be carried out with high accuracy, reliability and speed.