Patent ID: 6731390
Filing Date: 2004-05-04
Classification: G01B

Abstract:
The process for determining surface information by a projected structure with periodically changing brightness curve comprising steps of:shifting by 1/n, where n is a number greater than two, of the grating constant, acquiring the projection image by a CCD camera, determining information for every image point, which information represents the brightfield intensity multiplied by the respective grating phase, the sine components and cosine components being extracted from these images and giving: I. Ixy=Iobxy*m*sin x II. Ixy=Iobxy*m*cos x, andobtaining phase information &phgr;xy from I. and II. by division so as to associate the respective pixel above or below the focal plane: &varphi;xy=arctan&it;sin&it;â€ƒ&it;xcos&it;â€ƒ&it;xand wherein the structure is projected on the object surface at an angle of the principle beam other than 90Â°.