Surface feature evaluation with resolution beyond the classical diffraction limit can be achieved by a combined space--frequency representation of the scattered field. This was demonstrated in a measuring procedure where the surface was consecutively illuminated by a collection of focused beams and the diffracted data was measured in the far field. Mathematically, if the focused beam has a Gaussian profile, the optical system implements a Gabor transform. Other transformations, such as wavelet transforms can be obtained by properly structuring the illuminating beam. This work presents an approach where structured beams at several wavelengths are used. This additional information gathered by this procedure allows an increased resolution and the reduction of ambiguities that may occur in the analysis of single wavelength measurements.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.