Large-area full field x-ray differential phase-contrast imaging using 2D tiled gratings. (15th May 2017)

• Record Type: Journal Article
• Authors: Schröter, Tobias J; Koch, Frieder J; Kunka, Danays; Meyer, Pascal; Tietze, Sabrina; Engelhardt, Sabine; Zuber, Marcus; Baumbach, Tilo; Willer, Konstantin; Birnbacher, Lorenz; Prade, Friedrich; Pfeiffer, Franz; Reichert, Klaus-Martin; Hofmann, Andreas; Mohr, Jürgen
• Is Part Of: Journal of physics. Volume 50:Number 22(2017)
• Publication Date: 2017-05-15
• Subjects: x-ray imaging -- phase contrast -- LIGA -- large field of view -- x-ray grating; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/aa6e85
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Grating-based x-ray differential phase-contrast imaging (DPCI) is capable of acquiring information based on phase-shift and dark-field signal, in addition to conventional x-ray absorption-contrast. Thus DPCI gives an advantage to investigate composite materials with component wise similar absorption properties like soft tissues. Due to technological challenges in fabricating high quality gratings over a large extent, the field of view (FoV) of the imaging systems is limited to a grating area of a couple of square centimeters. For many imaging applications (e.g. in medicine), however, a FoV that ranges over several ten centimeters is needed. In this manuscript we propose to create large area gratings of theoretically any extent by assembling a number of individual grating tiles. We discuss the precision needed for alignment of each microstructure tile in order to reduce image artifacts and to preserve minimum 90% of the sensitivity obtainable with a monolithic grating. To achieve a reliable high precision alignment a semiautomatic assembly system consisting of a laser autocollimator, a digital microscope and a force sensor together with positioning devices was built. The setup was used to tile a first four times four analyzer grating with a size of 200 mm × 200 mm together with a two times two phase grating. First imaging results prove the applicability and quality of the tiling concept.