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Proceedings Paper

Grating based, phase contrast radiography with bremsstrahlung source
Author(s): F. Goldin; S. Hampton
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Paper Abstract

Phase-contrast radiography (PCR) generates an image from gradients in the phase of the probing X-radiation induced by the radiographic object, and can therefore make visible features difficult or impossible to see with conventional, absorption-contrast (ACR) radiography. For any particular object, variations in either the real or imaginary parts of the index of refraction could be greater. Most practical difficulties of PCR arise from the very small deviation from unity (~10-5-10-6, depending of material and energy) of the real part of the index of refraction. In principal, straightforward shadowgraphy would provide a phase-contrast image, but in practice this is usually overwhelmed by the zero-order (bright field) signal. Eliminating this sets the phase-contrast signal against a dark field (as in Schlieren photography with visible light). One way to do this with X-rays is with a grating that produces a Talbot interference pattern. Minute variations in optical path lengths through the radiographic object can significantly shift the Talbot fringes, and these shifts constitute a dark-field signal separate from the zero-order wave. This technique has recently been investigated up to ~20keV [1-3]; this work addresses what sets the practical upper limit, and where that limit is. These appear to be grating fabrication, and ~60keV, respectively.

Paper Details

Date Published: 11 September 2009
PDF: 13 pages
Proc. SPIE 7450, Penetrating Radiation Systems and Applications X, 74500K (11 September 2009); doi: 10.1117/12.824238
Show Author Affiliations
F. Goldin, National Security Technologies, LLC (United States)
S. Hampton, National Security Technologies, LLC (United States)

Published in SPIE Proceedings Vol. 7450:
Penetrating Radiation Systems and Applications X
F. Patrick Doty; H. Bradford Barber; Hans Roehrig; Richard C. Schirato, Editor(s)

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