The X-ray diffraction patterns dependence on the primary incident beam and on the methods of registration

The X-ray diffraction patterns obtained from plain-parallel crystalline plate with spherical cavity and from wedge-shaped crystal are investigated depending on the parameters (collimation) of the primary incident beam. It is shown that in the case of band-like incident beam the sectional topograms obtained from the wedge-shaped crystal have the form of v-shaped or straight fringes depending on the orientation of the reflecting plains relative to the surface of the X-ray band-like beam. In the case of a wide parallel beam or an asymmetrically reflected wide monochromatic beam the parallel fringes are obtained from the wedge-shaped crystals, and the circular fringes are obtained from the plain-parallel crystalline plates with spherical cavity. For the primary band-like beam the v-shaped patterns acquire the form of circular fringes as a result of scanning the crystal with spherical cavity and the film.