Lattice bending in x-ray interferometers

Abstract

This paper investigates both theoretically and experimentally the effect of lattice bending on the output signals of a two-crystal x-ray interferometer of the Laue LLL type. The cross section intensity of the outgoing beams is modulated by the moire effect produced by the overlapping of the analysing lattice on the x-ray standing field in front of it. Since the intensities of the transmitted and diffracted beams are integrated, the moire pattern causes loss of visibility in the x-ray fringes and a non-linear phase shift, which depends on the pitch alignment of the analysing crystal with respect to the fixed crystal. The analysis of this phase shift allows the lattice curvature to be estimated.