Abstract
The electron-microscope contrast at dislocations in isotropic and anisotropic cubic crystals has been computed on the basis of two-beam dynamic theory, using the column approximation. General regularities of dislocation images have been found for different diffraction conditions. It has been established that the intensity and character of contrast can be similar for the cases g · b = 0 and g · b = 2 close to Bragg diffraction conditions, whereas on deviating from the Bragg position the contrast differs essentially for these two cases. The effect of anisotropy on the contrast has been shown to differ for the cases when the anisotropy constant is greater or less then unity, A1,A1, and depends on the relative crystal stiffness along the crystallographic direction corresponding to the diffraction vector.