Abstract
Various X-ray optics with an optical length of 150-500 mm are employed for beam guidance, beam alignment and monochromatization. This paper focuses on two different types of large X-ray mirrors. The first optical element is a single-layer mirror which works as a total-reflection mirror in the soft X-ray range (50-200 eV) and at a grazing incidence angle of 2°. Such a mirror is used in free-electron lasers, e.g. FLASH in Hamburg, Germany. The second mirror is a multilayer mirror, which is employed as a reflector due to its Bragg reflection for the hard X-ray range (20-50 keV) and at incidence angles of 0.4-1°. Such a mirror could be used at a synchrotron storage ring for instance in a tomography beamline. In both cases, the mirrors were fabricated by means of state-of-the-art physical vapour deposition technique, using magnetron sputtering to achieve a good optical quality for their X-ray optical application. This deposition process allows a good run-to-run stability, which is crucial for the final deposition of the actual mirror on a high-quality substrate. Both the single and the multilayer mirror have a high reflectivity for their relevant energy range, a low roughness on their surfaces and a good uniformity of these properties over the whole optical length. The investigations described here were performed by means of X-ray reflectometry (XRR), transmission electron microscopy (TEM), optical profilometry (OP) and atomic force microscopy (AFM).
