Hard X-ray phase imaging and tomography with a grating interferometer

Timm Weitkamp, Ana Diaz, Bernd Nöhammer, Franz Pfeiffer, Torben Rohbeck, Peter Cloetens, Marco Stampanoni, Christian David

Research output: Contribution to journalConference articlepeer-review

38 Scopus citations

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.

Original languageEnglish
Article number94
Pages (from-to)137-142
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5535
DOIs
StatePublished - 2004
Externally publishedYes
EventDevelopments in X-Ray Tomography IV - Denver, CO, United States
Duration: 4 Aug 20046 Aug 2004

Keywords

  • Microtomography
  • Phase reconstruction
  • Phase-stepping interferometry
  • Synchrotron radiation
  • X-ray tomography

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