X-ray Multimodal Intrinsic-Speckle-Tracking

We develop X-ray Multimodal Intrinsic-Speckle-Tracking (MIST), a form of X-ray speckle-tracking that is able to recover both the refractive index decrement and the small-angle X-ray scattering (SAXS) signal of a phase object. MIST is based on combining a Fokker-Planck description of paraxial X-ray optics, with an optical-flow formalism for X-ray speckle-tracking. Only two images need to be taken in the presence of the sample, in order to recover both the refractive and local-SAXS properties of the sample. Like the optical-flow X-ray method which it generalizes, the method implicitly rather than explicitly tracks speckles. Application to X-ray synchrotron data shows the method to be efficient, rapid and stable.