Real-time Display System for Contour Lines and Equal-displacement Lines by Scanning Moire Method Using Phase-shifting

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Phase analysis of grid patterns obtained by grid projection methods is used to measure accurate shapes for 3-D objects, and also phase analysis of fringes obtained by interferometer is used to measure accurate flatness of plates. The accuracy of the phase analysis methods is 1110-1/1000 of a grid pitch or a wavelength of light.To analyze phase distributions of grids and fringe patterns, we proposed the Fourier transform method, the Gabol transform method and the wavelet transform method previously. We applied these methods to analysis of shapes and fringe patterns. However, phase analysis usually consumes much time. In this study, we propose four methods to measure shapes of 3-D objects or flatness of plates in real-time. The first is a phase-shifting scanning moire method. The second is a phase difference scanning moire method. The third is a phase-shifting method using the correlation of the rectangular brightness of a projected grid and two rectangular functions. The last is the integrated phase shifting method. These methods can provide accurate phase distributions in real-time.The principle and application applied to shape, strain and stress analysis are shown.