Lens-term-and edge-effect in X-ray grating interferometry

Johannes Wolf, Jonathan I. Sperl, Florian Schaff, Markus Schüttler, Andre Yaroshenko, Irene Zanette, Julia Herzen, Franz Pfeiffer

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9 Citations (Scopus)

Abstract

X-ray grating interferometry requires gratings with periods in the micrometer range and allows the acquisition of the dark-field contrast. The analyzer grating is designed to match the period of the interference pattern in order to translate it into a measurable intensity modulation. In this study, we explore the influence of a sample-induced mismatch between the interference pattern and the analyzer grating on the dark-field contrast. We propose a formula for the calculation of the signal due to a period mismatch and present estimations varying periods and detector pixel size. Furthermore, numerical simulations of the X-ray wave-front demonstrate that the wave-front curvature, described by the lens-term, e.g. behind a parabolic lens or edges of a sample can change the period of the interference pattern. Our results give a concrete explanation for the formation of a dark-field contrast from object edges and thus allow a better understanding of the dark-field signal obtained with a grating interferometer.

Original languageEnglish
Article number246902
Pages (from-to)4812-4824
Number of pages13
JournalBiomedical Optics Express
Volume6
Issue number12
DOIs
Publication statusPublished - 12 Nov 2015
Externally publishedYes

Keywords

  • X-ray imaging
  • X-ray interferometry

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