Abstract: A new method for the automatic processing of Young's fringes obtained from PIV photograph is presented. The fringe orientation is determined by searching for the maximum of the function W(α) constructed from the 2-D Young's fringe intensity distribution. The influence of the diffraction halo is removed by a simulated function constructed with normal function; the fringe spacing is derived from calculating 1-D Fourier transformation of 1-D fringe intensity distribution. Using this processing method, only a small amount of computation is required and a high measuring accuracy can be obtained (The measuring errors of fringe orientation and spacing are less than 0.5 ° and 1% respectively).

Key words: Young's fringes, particle image velocimetry, data processing