title: Influence of partial coherence on analyzer-based imaging with asymmetric Bragg reflection.
abstract: 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.
authors: Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany. peter.modregger@gmx.net
authors: Peter
authors: P
authors: Modregger
authors: Daniel
authors: D
authors: Lübbert
authors: Peter
authors: P
authors: Schäfer
authors: Jane
authors: J
authors: Richter
authors: Rolf
authors: R
authors: Köhler
authors: Tilo
authors: T
authors: Baumbach
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004867:Equipment Design; D005583:Fourier Analysis; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D015233:Models, Statistical; D008962:Models, Theoretical; D055095:Optics and Photonics; D017356:Synchrotrons; D014965:X-Rays