X-ray interferometer with bent gratings: Towards larger fields of view

Recently, a Talbot-Lau interferometer was proposed to achieve phase contrast and dark field imaging in the hard X-rays domain (10-100 key). This technique attracts much interest since it does not impose strong requirements on the coherence of the radiation while being sensitive to small phase changes of the beam. However, the limited size of the field of view, some centimeters, prevents its use in many applications where large objects have to be investigated. In the following article, the authors investigate a solution to extend the size of the field of view. After introducing the fundamental limitation on the size of the field of view, a Talbot-Lau interferometer with gratings bent on a cylindrical form is proposed and demonstrated in a compact (60 cm-long) configuration. A significant improvement of the performance could be achieved in comparison to the standard geometry. The theoretical limit imposed by the non-perpendicular angular incidence can thus be practically overcome and large fields of view become realistic. The authors envision a significant impact for high resolution phase sensitive imaging and/or industrial systems. (c) 2010 Elsevier B.V. All rights reserved.