Digital correlation of grainy shadow images for surface profile measurement

An optical method, combining the projection of a structured light pattern with the digital correlation technique, is discussed in this paper. This method allows measurement of full-field profile on object surface of about 20 mm square size. Tests on a rotated plane surface have been performed in order to quantify the method capabilities. It is shown that this technique leads to an accuracy of about 1 μm for a spatial resolution of around half a millimeter. Profile measurements of a micro-engraved object and at the crack tip of a polymer sample are also presented. Results give proof that this technique remains efficient even in presence of important height slope.