Quantitative Non-Interferometric X-Ray Phase Imaging

Abstract

The phase of a coherent wave is an intuitively well understood concept and efforts to measure the phase of a wave are a staple of visible, x-ray, electron and atom optics. However, in a subtle way, phase is often measured where it is not even defined. An example of this is adaptive optics where the atmospheric phase distortion of light from astronomical objects is measured using polychromatic light. The assumption buried under this work is that it is possible to sensibly talk about phase even though the context of the discussion does not permit phase to be defined according to elementary concepts.We have been undertaking an ongoing program investigating the nature of wavefields and exploring their characterisation using more robust approaches than standard techniques such as interferometry In a very recent paper we have developed a new viewpoint on phase defined via the Poynting vector of the radiation and where the phase acts as a set of potentials leading to the Poynting vector field.