Diffraction image of a narrow X-rays beam in crystals with weak deformation.

The problem of the dynamic diffraction of X-rays from a point source on the spatial lattice of a crystal weakly deformed by a temperature gradient is considered. The Theoretical study is based on the asymptotic representation of the Green-Riemann function for a pair of Takagi equations of the hyperbolic type. The Experimental studies were carried out on the quartz crystals in the presence of a temperature gradient that is perpendicular to the reflecting planes. The conditions and characteristics of focusing are considered, taking into account the distances source-crystal-detector and the parameter of the deformation field. [ABSTRACT FROM AUTHOR]