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

Several hard X-rays imaging techniques greatly benefit from the coherence o f the beams delivered by the modern synchrotron radiation sources. This is illustrated with examples recorded on the 'long' (145 m) ID19 'imaging' bea mline of the ESRF. Phase imaging is directly related to the small angular s ize of the source as seen from one point of the sample ('effective divergen ce' similar or equal to microradians). When using the 'propagation' techniq ue, phase radiography and tomography are instrumentally very simple. They a re often used in the 'edge detection' regime, where the jumps of density ar e clearly observed. The in situ damage assessment of micro-heterogeneous ma terials is one example of the many applications. Recently a more quantitati ve approach has been developed, which provides a three-dimensional density mapping of the sample ('holotomography'). The combination of diffraction to pography and phase-contrast imaging constitutes a powerful tool. The observ ation of holes of discrete sizes in quasicrystals, and the investigation of poled ferroelectric materials, result from this combination.