Open AccessInfluence of partial coherence on analyzer-based imaging with asymmetric Bragg reflection
Author(s) -
Peter Modregger,
D. Lübbert,
P. Schäfer,
Jane Richter,
R. Köhler,
Tilo Baumbach
Publication year - 2009
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.17.011618
Subject(s) - optics , monochromatic color , physics , bragg's law , magnification , ptychography , coherence (philosophical gambling strategy) , image resolution , phase contrast imaging , synchrotron radiation , formalism (music) , diffraction , phase contrast microscopy , art , musical , quantum mechanics , visual arts
Image magnification via twofold asymmetric Bragg reflection (a setup called the "Bragg Magnifier") is a recently established technique allowing to achieve both sub-micrometer spatial resolution and phase contrast in X-ray imaging. The present article extends a previously developed theoretical formalism to account for partially coherent illumination. At a typical synchrotron setup polychromatic illumination is identified as the main influence of partial coherence and the implications on imaging characteristics are analyzed by numerical simulations. We show that contrast decreases by about 50% when compared to the monochromatic case, while sub-micrometer spatial resolution is preserved. The theoretical formalism is experimentally verified by correctly describing the dispersive interaction of the two orthogonal magnifier crystals, an effect that has to be taken into account for precise data evaluation.