Theory of oblique and grazing incidence Talbot‑Lau interferometers and demonstration in a compact source x‑ray reflective interferometer

• Published in: Optics express Vol. 19; no. 25; pp. 25093 - 25112
• Main Authors: Wen, Han, Kemble, Camille K, Bennett, Eric E
• Format: Journal Article
• Language: English
• Published: United States Optical Society of America 05.12.2011
• Subjects: Computer Simulation; Computer-Aided Design; Equipment Design; Equipment Failure Analysis; Interferometry - instrumentation; Models, Theoretical; Scattering, Radiation; X-Ray Diffraction - instrumentation; X-Rays
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.19.025093

With the advent of Talbot-Lau interferometers for x-ray phase-contrast imaging, oblique and grazing incidence configurations are now used in the pursuit of sub-micron grating periods and high sensitivity. Here we address the question whether interferometers having oblique incident beams behave in the same way as the well-understood normal incidence ones, particularly when the grating planes are non-parallel. We derive the normal incidence equivalence of oblique incidence geometries from wave propagation modeling. Based on the theory, we propose a practical method to correct for non-parallelism of the grating planes, and demonstrate its effectiveness with a polychromatic hard x-ray reflective interferometer.