title: Single-distance phase retrieval at large phase shifts.
abstract: For coherent X-ray imaging of pure phase objects we study the reliability of linear relations in phase-retrieval algorithms based on a single intensity map after free-space propagation. For large phase changes and/or large propagation distances we propose two venues of working beyond linearity: Projection onto an effective, linear and local model in Fourier space and expansion of intensity contrast in powers of object-detector distance. We apply both algorithms successfully to simulated data.
authors.affiliation: Laboratorium für Applikationen der Synchrotronstrahlung, Karlsruher Institut für Technologie, Postfach 6980, D-76128 Karlsruhe, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Moosmann
authors.forename: Ralf
authors.initials: R
authors.lastname: Hofmann
authors.forename: Tilo
authors.initials: T
authors.lastname: Baumbach
mesh_terms: D000465:Algorithms; D000818:Animals; D005583:Fourier Analysis; D016014:Linear Models; D017711:Nonlinear Dynamics; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D017356:Synchrotrons; D014056:Tomography, X-Ray / Q000379:methods*; D014981:Xenopus