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Proceedings Paper

Phase retrieval in coherent diffraction from Cu3Au antiphase domains
Author(s): John A. Pitney; Ivan A. Vartaniants; Ian K. Robinson
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Paper Abstract

Below its critical temperature (668 K), crystals of the binary alloy Cu3Au consist of antiphase domains with a length scale determined by growth conditions and annealing history. Superstructure Bragg reflections indicate the extent of long-range ordering of the domains. The use of a coherent beam causes these superstructure peaks to have the appearance of speckles, which have a size determined by the size of the beam. The speckles result from a scattering process with no ensemble averaging and thus describe the specific microscopic arrangement of the domains within the illuminated volume of the sample. However, in real experiments only the diffracted beam intensity can be measured while all phase information is lost. This problem is overcome in conventional holography by the construction of a reference wave; however, the special requirements of x- ray optical design have precluded the direct applications of this approach, and so the use of numerical analysis is required. Iterative methods, including the Gerchberg-Saxton algorithm and the hybrid input-output algorithm, have been successfully demonstrated for computer simulations of Cu3Au and show early promise for reconstruction of domain structure from real measurements. Data obtained at the Advanced Photon Source beamline 33-ID-D at 8.5 keV are presented, and the requirements for successful reconstruction of images from such data are discussed.

Paper Details

Date Published: 30 September 1999
PDF: 9 pages
Proc. SPIE 3815, Digital Image Recovery and Synthesis IV, (30 September 1999); doi: 10.1117/12.364130
Show Author Affiliations
John A. Pitney, Univ. of Illinois/Urbana-Champaign (United States)
Ivan A. Vartaniants, Institute of Crystallography (Russia)
Ian K. Robinson, Univ. of Illinois/Urbana-Champaign (United States)

Published in SPIE Proceedings Vol. 3815:
Digital Image Recovery and Synthesis IV
Timothy J. Schulz; Paul S. Idell, Editor(s)

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