Abstract

Despite the fact that roughness of the boundaries reduces the reflectivity of normal incidence multilayer mirrors by a large factor for wavelengths λ < 100 Å, no loss in image quality from scattering has been observed up to now. Analysis of images of the solar corona give an upper limit on the amount of scattering, and we compare these results to data on the surface topography of the mirror surface and to measurements of scattering at λ = 1.54 Å. The data demonstrate the reduction in scattering from a multilayer structure when it is illuminated near the reflectivity maximum. We also compare the different measurement methods and show that the widely used rocking curve scan is not suitable to show this effect and to predict the performance of a mirror for imaging applications.

© 1991 Optical Society of America