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Proceedings Paper

Hard x-ray phase imaging and tomography with a grating interferometer
Author(s): Timm Weitkamp; Ana Diaz; Bernd Nohammer; Franz Pfeiffer; Torben Rohbeck; Peter Cloetens; Marco Stampanoni; Christian David
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Paper Abstract

We have developed a two-grating interferometer for hard X rays that can be used for phase imaging and tomography. A silicon phase grating positioned just downstream of the object under study splits the distorted wavefront into essentially a positive and a negative first-order beam. At a given distance from this beam-splitter grating, where the two beams still mostly overlap, they form a pattern of interference fringes that is distorted according to the wavefront distortions. The fringes may be finer than the resolution of an area detector used to record the signal, but an absorption grating with suitable pitch, put in front of the detection plane, allows the detection of intensity variations that correspond to the derivative of the wavefront phase taken along the direction perpendicular to the grating lines. A combination of this technique with the phase-stepping method, in which several exposures are made which differ in the phase of the fringe pattern, allows to eliminate effects of non-uniform intensity due to inhomogeneous illumination and edge-enhancing inline phase contrast. Several examples of tomograms taken under different experimental conditions are shown, including a polychromatic "pink-beam" setup.

Paper Details

Date Published: 26 October 2004
PDF: 6 pages
Proc. SPIE 5535, Developments in X-Ray Tomography IV, (26 October 2004); doi: 10.1117/12.569643
Show Author Affiliations
Timm Weitkamp, Paul Scherrer Institut (Switzerland)
Ana Diaz, Paul Scherrer Institut (Switzerland)
Bernd Nohammer, Paul Scherrer Institut (Switzerland)
Franz Pfeiffer, Paul Scherrer Institut (Switzerland)
Torben Rohbeck, Paul Scherrer Institut (Switzerland)
Peter Cloetens, European Synchrotron Radiation Facility (France)
Marco Stampanoni, Paul Scherrer Institut (Switzerland)
Christian David, Paul Scherrer Institut (Switzerland)

Published in SPIE Proceedings Vol. 5535:
Developments in X-Ray Tomography IV
Ulrich Bonse, Editor(s)

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