Strain and Shape Measurements by Scanning Moire Method and Fourier Transform Moire Method
Image processing is a powerful technique for analyzing the fringe patterns obtained by whole- field methods such as geometric moire, holographic interferometry, photoelasticity, etc. In addition to eliminating tedious and time consuming calculations, image processing creates the possibility of new methods of analysis. In this paper, two new moire methods using image processing are presented. One is the scanning moire method in which the scanning lines of a TV camera or the sampling points of an image processor interfere with the model grating lines to create a moire pattern. The other is the Fourier transform moire method which uses the shifted first harmonic of the Fourier spectra of a model grating to yield a sinusoidal brightness distribution corresponding to fractional fringe orders. These methods produce clear moire patterns and permit automated high speed analysis. The outline of these methods and some applications are given.
KeywordsPoint Image Fringe Pattern Scanning Line Holographic Interferometry Fringe Order
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