Directional dark-field implicit x-ray speckle tracking using an anisotropic-diffusion Fokker-Planck equation

When a macroscopic-sized noncrystalline sample is illuminated using coherent x-ray radiation, bifurcation of photon energy flow may occur. The coarse-grained complex refractive index the be considered to attenuate and refract incident beam, leading component transmitted beam. Spatially unresolved microstructure, associated with fine-grained components index, introduces diffuse This photon-scattering channel viewed in terms position-dependent fans ultrasmall-angle scatter. These fans, at exit surface object, under certain circumstances approximated as having locally elliptical shape. By an anisotropic-diffusion Fokker-Planck approach model this bifurcated flow, we show how all three (attenuation, refraction, scatter) recovered. done via speckle tracking, which spatially random fields generated by illumination membrane. theory developed then successfully applied experimental data.