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 and it is shown that both can be obtained separately from a measured reflectivity curve at a short x-ray wavelength. Multilayers have greatly 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. © 1985 SPIE.