X-ray linear dichroic ptychography

Abstract

Significance Ptychography, a powerful scanning coherent diffractive imaging method, has attracted considerable attention for its general applicability. Here, we demonstrate X-ray linear dichroic ptychography to study the crystal orientations of the calcium carbonate in coral samples. In contrast to the absorption contrast commonly observed in linear dichroic imaging, dichroic ptychography at pre-oxygen K-edge shows significant and unique dichroic phase contrast, which has not been reported. The dichroic ptychography images reveal the presence of both narrow and wide c -axis angular spread in the submicrometer coral fragments, which are confirmed by 4D STEM. We expect X-ray linear dichroic ptychography to be a high-resolution, dose-efficient tool to broadly study optically anisotropic materials such as tooth enamel, bone, seashells, brittlestars, and polymers.