Phase imaging using highly coherent X-rays: radiography, tomography, diffraction topography

Several hard X‐rays imaging techniques greatly benefit from the coherence of the beams delivered by the modern synchrotron radiation sources. This is illustrated with examples recorded on the `long' (145 m) ID19 `imaging' beamline of the ESRF. Phase imaging is directly related to the small angular size of the source as seen from one point of the sample (`effective divergence' ≃ microradians). When using the `propagation' technique, phase radiography and tomography are instrumentally very simple. They are often used in the `edge detection' regime, where the jumps of density are clearly observed. The in situ damage assessment of micro‐heterogeneous materials is one example of the many applications. Recently a more quantitative approach has been developed, which provides a three‐dimensional density mapping of the sample (`holotomography'). The combination of diffraction topography and phase‐contrast imaging constitutes a powerful tool. The observation of holes of discrete sizes in quasicrystals, and the investigation of poled ferroelectric materials, result from this combination