title: Phase retrieval by coherent modulation imaging.
abstract: Phase retrieval is a long-standing problem in imaging when only the intensity of the wavefield can be recorded. Coherent diffraction imaging is a lensless technique that uses iterative algorithms to recover amplitude and phase contrast images from diffraction intensity data. For general samples, phase retrieval from a single-diffraction pattern has been an algorithmic and experimental challenge. Here we report a method of phase retrieval that uses a known modulation of the sample exit wave. This coherent modulation imaging method removes inherent ambiguities of coherent diffraction imaging and uses a reliable, rapidly converging iterative algorithm involving three planes. It works for extended samples, does not require tight support for convergence and relaxes dynamic range requirements on the detector. Coherent modulation imaging provides a robust method for imaging in materials and biological science, while its single-shot capability will benefit the investigation of dynamical processes with pulsed sources, such as X-ray free-electron lasers.
authors.affiliation: London Centre for Nanotechnology, University College London, London WC1E 6BT, UK.|Research Complex at Harwell, Harwell Campus, Didcot OX11 0FA, UK.|Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
authors.forename: Fucai
authors.initials: F
authors.lastname: Zhang
authors.affiliation: London Centre for Nanotechnology, University College London, London WC1E 6BT, UK.|Research Complex at Harwell, Harwell Campus, Didcot OX11 0FA, UK.|School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Chen
authors.affiliation: London Centre for Nanotechnology, University College London, London WC1E 6BT, UK.|Research Complex at Harwell, Harwell Campus, Didcot OX11 0FA, UK.
authors.forename: Graeme R
authors.initials: GR
authors.lastname: Morrison
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: Joan
authors.initials: J
authors.lastname: Vila-Comamala
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
authors.forename: Manuel
authors.initials: M
authors.lastname: Guizar-Sicairos
authors.affiliation: London Centre for Nanotechnology, University College London, London WC1E 6BT, UK.|Research Complex at Harwell, Harwell Campus, Didcot OX11 0FA, UK.|Condensed Matter Physics and Materials Department, Brookhaven National Lab, Upton, New York 11973, USA.
authors.forename: Ian K
authors.initials: IK
authors.lastname: Robinson