On one Method of Increasing the Resolution of X-Ray Diffraction Patterns

A new method for recording fine structures of X-ray diffraction patterns formed in 3-block interferometers with a violated ideal geometry is presented in this work. To apply and verify the proposed method a new monolithic 4-block diffraction system is designed, manufactured, and tested. It consists of 3 thin blocks forming a 3-block interferometer with a violated geometry, and additional 4th thick block in the reflection mode. The inclusion of the 4th thick block enables the observation of fine structures of interference patterns formed in a 3-block defocused interferometer. It was shown that an interference pattern is formed in a 3-block interferometer in the form of families of parallel stripes (lines) in a plane perpendicular to the diffraction vector when its ideal geometry is violated. It was confirmed that the thick block increases the pattern size in the scattering plane, but does not add new information to the interference pattern. However, the fine structure of X-ray interference patterns obtained from 3-block interferometers with violated geometry can also be revealed when their splitter and mirror blocks are thin, while the 3rd block analyzer is thick. The limits for reducing the period of interference stripes until their complete disappearance due to the defocusing, as well as “allowed violations” of the ideal geometry of real 3-block interferometers (when the interference still is observable) are determined. Analysis of X-ray diffraction patterns formed in both a 3-block defocus interferometer and a narrow-gap double-crystal system has revealed their similarity.