Fabrication of Silicon Structures for Speckle-based X-ray Phase Contrast Imaging
Phase contrast X-ray imaging is an excellent technique for the investigation of samples in biology, materials science and energy science. In recent years, speckle-based X-ray imaging has been proven as a new approach to obtain the phase and dark-field information of the object under study. This technique uses an optical element (typically, an ordinary sandpaper foil with a fine grain size) to produce a speckled pattern in the X-ray image. The changes in the speckled pattern after introducing the sample can be used to detect the refraction and the scattering signals of the sample. In this work, we investigate the use of a tailored optical element made of silicon structures in the submicrometer range to achieve higher spatial resolution and address other challenges of the method such as the non-uniformity of the phase sensitivity over the whole field of view of the X-ray imaging setup. The silicon nanostructures are created by metal assisted chemical etching (MacEtch) using gold as catalyst.