8-inch-diameter field of view for X-ray differential phase-contrast imaging

Abstract

The X-ray differential phase-contrast imaging (DPCI) based on Talbot–Lau​ interferometers (TLIs) is a promising imaging technique for non-destructive testing. The compact imaging configurations that have a large field-of-view (FoV) require the use of bent phase gratings and large-area analyzer gratings. The cascaded TLIs reduce the aspect ratio requirement of large-area analyzer gratings, which facilitates the fabrication of these gratings. However, the bent silicon-based phase gratings are difficult to obtain directly because of the brittleness of silicon wafers. In this work, we present a method to prepare 5-inch cylindrically bent silicon-based phase gratings and 8-inch analyzer gratings. Moreover, we also present their applications in the cascaded TLIs. The mechanical stress that originates from thermal oxidation enables us to cylindrically bend silicon-based phase gratings. Furthermore, as compared to the use of plane phase gratings, the use of cylindrically bent phase gratings allows Moiré fringes to appear in the entire 8-inch FoV. Finally, Moiré fringes and multi-contrast images of the samples (water, liquid soap filled in heat-shrink tubes) demonstrate the effectiveness of the fabrication of the bent silicon-based phase gratings and imaging in the entire 8-inch FoV. The proposed configuration is applicable for attaining multi-contrast images with 8-inch FoV at a low cost.