Imaging Analysis and Application of Digital Speckle Photography with EALCD

Abstract

According to the principle of speckle photography, CCD(Charge-Coupled Device) as a recorder, and EALCD(Electrically Addressed Liquid Crystal Display) as a read-out element, which makes the speckle photography to digital. Recording light path of the subjective and the objective speckle and observation light path of full-field analysis and point-by-point analysis for fringe reconstruction have been respectively researched. At the same time, measuring by speckle photography, the fringes in the interometry pattern must be carefully analyzed. Since the speckle noise can greatly infect the signals. Thus to de-noising the speckle fringe by a suitable filter before processing is expected. The mathod of digital filter enhancement, smooth denoising be used to reduce the influence of the high noise and the inhomogeneous grey of the speckle interferogram. Finally the thinning fringe is acquired, the fringe spacing is extracted accurately, the three-dimensional measurement of a deformed object is realized with mathematical morphological thinning algorithm.