Sub-micrometre coherent beams from x-ray waveguides: principles and applications

The operating principle and some applications of the x-ray waveguides are revised. Significant improvements in waveguide fabrication with respect to the first ones yielded gain of about a factor six with respect to the incident intensity. The high degree of coherence and the divergence of the beam exiting the waveguide allowed phase contrast experiments with unprecedented spatial resolution of 140 nm. An innovative geometry for microdiffraction experiments is proposed which can open the way to very high spatial resolution measurements. The results of a very recent test experiment on a patterned silicon crystal are presented.