Hard X-ray stereographic microscopy for single-shot differential phase imaging

The characterisation of fast phenomena, exhibiting velocities of metres per second and more, occurring in opaque samples requires adequate X-ray imaging methods for revealing such structures in their natural state. Fast processes are often stochastic in nature and occur in many key technologies such as additive manufacturing or micro-fluidics, e.g. turbulent cavitations or shock-wave propagation. Due to the complexity of such structures and the speed of the dynamic processes involved, it is necessary to collect 3D structural information for each relevant point in time. Sensitivity to small density differences in a sample can be greatly enhanced, especially for soft matter, by exploiting the phase-contrast modality. In this work, we demonstrate a combination of X-ray stereography and differential phase contrast microscopy with a single-shot (i.e. single exposure) acquisition, paving the way to 3D movies by using sequential "shots" to each collect 3D information. We show that we can successfully recover the 3D phase volume of a phantom object using two simultaneously recorded, stereographic X-ray views. The proposed method is extendable to more than two angular projections and has great potential for applications at megahertz X-ray Free Electron Lasers (XFELs), where velocities of up to kilometres per second can be temporally resolved