M. Wieczorek, F. Schaff, F. Pfeiffer, T. Lasser Anisotropic X-Ray Dark-Field Tomography: A Continuous Model and its Discretization Phys. Rev. Lett. 117, 158101, 2016 (bib)
	The x-ray dark-field signal measured in grating interferometers is anisotropic, depending on both the beam direction and the grating orientation with respect to the sample. We present a novel general closed-form, continuous forward model of the anisotropic dark-field signal. Furthermore, we derive a discretization using spherical harmonics, leading to a large-scale linear inverse problem. We present first experimental results of a wooden sample, demonstrating marked advantages over previous results, in particular, the resolution of multiple scattering directions in one volume element.
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