Projection moire with moving gratings for automated 3-D topography

Abstract

A method is presented that permits a vast increase in the capability of projection moire topography. It involves simultaneous translation of the reference and object gratings to generate high-definition contour fringes without any of the artifacts associated with ordinary moire. Experimental results are presented for single- and double-projection arrangements for a general 3-D object and an inclined-plane test surface. Clear contouring fringes for angles of inclination up to 80° are shown, and fringe densities higher than the grating frequency are obtained. Coupled with the flexibility of projection moire, this technique is shown to be particularly suited for computer-assisted moire fringe pattern analysis. Means of practical implementation in on-line processing system are proposed.