A study of the validity of the image deconvolution method on the basis of channelling theory for thicker crystals

The image deconvolution method in high-resolution electron microscopy is theoretically studied for the applications in materials science. The weak-phase object approximation is replaced by a new formulation of diffraction wave function based on the channelling theory [D. Van Dyck, M. Op de Beeck, Ultramicroscopy 64 (1996) 99] which is valid for rather thicker crystals. It is shown that in some special cases, the phases of two-dimensional structure factors can be reliably determined by the compensation for contrast transfer function on the images of thicker crystals. Furthermore, the projected atomic columns are always displayed at the correct positions in the deconvoluted images, In contrast to the weak phase: object approximation. however. the projected column image intensities are non-linearly related to the projected atomic potential. (C) 1999 Elsevier Science B.V. All rights reserved.