From Phase-Contrast and Scattering Micro-CT to X-ray Tensor Tomography XTT

Dr. Simon Zabler, Chair of X-ray Microscopy LRM,
Institute of Physics, University Wurzburg – Germany

Abstract
With the advent of grating-based X-ray phase contrast (GBPC) imaging, we could record transmission images of large (centimeter) objects while being sensitive to scattering angles of the order of tens of micro-radians. Scattering occurs both coherently (refraction and diffraction) and incoherently (dark field image contrast DIC). Coherent scattering can be employed for sensing the X-ray wave front by analyzing the Talbot carpet or by recording differential phase contrast (DPC) images of weakly absorbing materials. Incoherent scattering on the other hand is even more important to materials research for detecting density and anisotropy of microscopic interfaces (fibers, tubes, pores and inclusions) in large objects. By combining thirteen DIC scans into one iterative volume reconstruction one can retrieve an accurate 3D picture, e.g. of the local fiber orientation and density in carbon fiber reinforced plastic components. Exploiting this capability of sensing sub-voxel information in X-ray Tensor Tomography XTT poses a challenge to signal processing. At the LRM we employ SAXS and high-resolution region-of-interest sub-µ and Nano-CT scanners for refining the physical scattering model to match observations by XTT.