Investigation of X-Ray Optical Anisotropy of Materials by means of X-Ray Interferometry

摘要

A novel approach is proposed in the present work for investigation of X-ray optical anisotropy of materials, that is based on X-ray interferometric method of measurements. Unlike the existing methods, where the specimen to be tested is placed in the path of one of interfering beams, in the proposed approach the specimens under investigation are placed directly in the paths of both the interfering beams, owing to which the impact of other factors on the shift of interference Moire fringes is eliminated. In this way the Moire fringes simultaneously appear during the same exposure both in the absence and presence of specimens with different orientations of optical axes. Due to the fact that the relative displacement of Moire fringes is observed in three different columns of the same beam, it becomes possible to simultaneously observe and immediately identify the presence of X-ray optical anisotropy, as well as to measure the values of refractive indices n_o and n_e for specimens under study. By means of proposed method the X-ray optical anisotropy of cellophane film was registered and values of refractive indices n_o and n_e for cellophane were measured. It was established that cellophane is X-ray optically positive anisotropic medium.