HIGH-RESOLUTION SURFACE RECONSTRUCTION USING OPTICALLY MEASURED GABOREXPANSION COEFFICIENTS

We describe a new optical inspection method based on the analysis of t he combined space-frequency representation of the scattered field. Sam ples of the sliding window spectrum are measured optically and then th e surface features are reconstructed by numerical methods, The methods investigated include reconstruction from the Gabor expansion coeffici ents, using the Zak transform, and phase recovery from amplitude only data, using projection onto constraint sets algorithm, Computer simula tions and experimental results show that this method can reconstruct a ccurately shallow phase objects, even when their dimensions are smalle r than the diffraction limit of the optical setup. (C) 1997 Society of Photo-Optical Instrumentation Engineers.