Pixel-wise quantitative dark-field imaging in a lab-based dual-phase X-ray grating interferometer

Investigating structures in the sub-micron range with lab-based X-ray micro-computed tomography (micro-CT) is challenging due to the limitations posed by the spot size and CT's inherent trade-off between spatial resolution and sample size. The dual-phase X-ray grating interferometer, which can be implemented within a micro-CT system, provides a promising solution to these challenges. By exploiting the tunability of the dark-field signal provided by the dual-phase X-ray grating interferometer, we present an algorithm that enables pixel-wise quantitative characterization of sub-micron structures, while simultaneously capturing macroscopic heterogeneity on the centimeter scale. The method further mitigates the visibility hardening effect in the dark-field signal, a spectral artifact resulting from the polychromatic source, ensuring the accurate characterization of sub-micron structures with a lab-based setup. This algorithm is validated using both simulations and experiments, bringing quantitative dark-field analysis out of synchrotron environments and establishing a lab-based multi-scale imaging technique.