Large area gratings by x-ray LIGA dynamic exposure for x-ray phase-contrast imaging

Abstract

X-ray differential phase-contrast imaging (DPCI) using a Talbot–Lau interferometer at a conventional tube source has continuously found applications since its first demonstration. It requires high aspect ratio grating structures with a feature size in the micrometer range that are fabricated using lithographie, galvanik und abformung technology. To overcome the current limitation in grating area, an exposure strategy—continuous exposure—has been developed. In this case, the mask is fixed in respect to the synchrotron beam and only the substrate is scanned. Thus, the grating area is given by the scanning length which is much larger than the actual mask size. The design, needs, and tolerances to adopt this process of dynamic exposure will be described. Furthermore, the first tests using this method will be presented. Gratings with a metal aspect ratio of 11 and a period of 10 μm were fabricated on an area of 165 mm×65 mm. First imaging results demonstrate the suitability of this method. No differences in the visibility or in x-ray image compared to gratings fabricated by the standard method could be found.