Abstract

Smooth boundaries with a sharp transition between the layers are required in high performance multilayer mirrors, especially those to be used in the ultraviolet and x-ray range. Ion polishing at grazing angles of incidence can be used to improve the quality of the boundaries. Characterization of the boundaries with high resolution is required to optimize the process. We use in situ soft x-ray reflectivity of the growing film for the first characterization. The finished mirrors are tested at grazing angle of incidence with λ = 1.54 Å and with synchrotron radiation in the λ = 44-58-Å range and all these tests give consistent results. We present data on multilayer coatings for x-ray telescopes, where the accumulation of roughness from layer to layer has been eliminated by the polishing process and where reflectivities have been enhanced by more than a factor of 2. Tunnel microscopy of the mirror surface gives lateral and depth resolution below the 1-Å range, and we compare the data from tunnel micrographs with those obtained by other methods.

© 1989 Optical Society of America