Experimental Investigation of X-Ray LLL Interferometers with a Wedge-Shaped Mirror Block and the Hard Bases

Two X-ray LLL interferometers are investigated experimentally and with some theoretical explanations: one with a wedge-shaped mirror block and the other one is called hard. The received interference images show that the moiré images are also superposed on the pendellözung fringes in the roentgenograms obtained from the interferometers with a wedge-shaped mirror block and do not interact. The period of pendellözung fringes does not change after passing through the analyzer. The theory of the eikonal approximation of interference fringes formation in the interferometer with a wedge-shaped mirror plate gives predictions that coincide with the obtained experimental results. Unlike a typical LLL X-ray interferometer, the hard one has a base and a “ceiling”. The hard interferometer does not produce uncontrolled moiré thanks to such a structure. The latter occurs because of the interferometer plate deformations: the hard interferometer is much more sensitive to mechanical stresses and various external factors.