X-Ray Three-Crystal Interferometer with Manual Control

An X-ray three-block interferometer with a thin neck between the analyzer and mirror blocks is designed. The mutual arrangement of these blocks is changed with the help of levers with weights at the ends, which made it possible to rotate the analyzer block with the splitter blocks (S) and the mirror block fixed. Sectional topograms of interference patterns at different torques show that rotational moire prevails in the recorded moire patterns. With an increase in the mechanical torque, the period of the moire fringes increases; at some moment, the moire pattern disappears, and the interference field becomes uniform, which means that the interferometer becomes an "ideal": further increase in the torque results in the appearance of a rotational moire with a change in the sign of the slope of the interference fringes. A theoretical interpretation of all observed phenomena is given.