X-ray interferometry technique for mirror and multilayer characterization

X-ray beams delivered by third generation synchrotron radiation machines have a high degree of coherence that allows to use different coherent imaging techniques such as phase contrast microscopy, holography, and phase-contrast tomography in the high-energy domain. The question arises to what extent the existing optical elements such as mirrors and multilayers are capable of preserving this high spatial coherence. A theory of partially coherent x-ray scattering by a slightly modulated mirror surface under total reflection is developed. This gives estimations for intensity contrast as a function of the surface modulation. X-ray topography with coherent light is proposed and applied for mirror diagnostics. X-ray interferometry in an in-line holography setup is used to describe the coherence properties of the x-ray beam including optical components like mirror and multilayers. It is shown that significant improvements of the polishing process are still needed for the long mirrors while small state-of-the-art mirrors (less than 100 nm) are nearly adequate.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.