DETERMINATION OF THICKNESS ERRORS AND BOUNDARY ROUGHNESS FROM THE MEASURED PERFORMANCE OF A MULTILAYER COATING.

The influence of thickness errors and boundary imperfections on the performance of a multilayer x-ray mirror is discussed. It is shown that both can be obtained separately from a measured reflectivity curve at a short x-ray wavelength. Multilayers have reduced scattering compared to single films, and for this reason rough boundaries and gradual transition layers between the film materials give practically identical performance. A simple Debye-Waller factor is not sufficient to describe the performance of a multilayer with many layers at short wavelengths.