Physical analysis of the inverse problem of X-ray reflectometry

A new approach to the inverse problem of X-ray reflectometry is discussed. The problem consists in a reconstruction of the depth-distribution of the dielectric permeability basing on measurements of the intensity reflectivity in a limited range of an incidence angle. A key feature of the approach consists in modeling of the amplitude reflectivity in the whole range of the incidence angle instead of direct modeling of the dielectric constant profile. The modeling is possible if the points of discontinuity of the dielectric constant distribution are known. In its turn, the information about these points can be extracted from the measured part of the reflectivity curve. Examples demonstrating high potentiality of the approach are presented. The uniqueness of the inverse problem solution is discussed. (C) 2003 Elsevier Science B.V. All rights reserved.