Patent ID: 7812942

Claim:
A method for detecting surface defects, on a substrate designed to be used in electronics, optoelectronics or analogue, the method comprising: projecting a pattern composed of an alternation of light fringes and dark bands on the substrate, so as to generate fringes reflected by the surface of the substrate; relatively displacing the pattern and the substrate along at least one direction, so as to displace the fringes of the pattern on the substrate, wherein the fringes of the pattern are parallel to each other and extend parallel to a second principal crystalline axis of the substrate; acquiring a sequence of at least three images of the pattern reflected by the substrate by a sensor, the images corresponding to displacement of the fringes of the pattern; determining the gradient of the surface of the substrate using displacements of fringes of the pattern, and determining the presence of a surface defect on the substrate using variations in the gradient of the surface of the substrate.