title: Properties of broadband depth-graded multilayer mirrors for EUV optical systems.
abstract: The optical properties of a-periodic, depth-graded multilayer mirrors operating at 13.5 nm wavelength are investigated using different compositions and designs to provide a constant reflectivity over an essentially wider angular range than periodic multilayers. A reflectivity of up to about 60% is achieved in these calculation in the [0, 18 degrees] range of the angle of incidence for the structures without roughness. The effects of different physical and technological factors (interfacial roughness, natural interlayers, number of bi-layers, minimum layer thickness, inaccuracy of optical constants, and thickness errors) are discussed. The results from an experiment on the fabrication of a depth-graded Mo/Si multilayer mirror with a wide angular bandpass in the [0, 16 degrees] range are presented and analyzed.
authors.affiliation: FOM-Institute for Plasma Physics Rijnhuizen, NL-3430 BE Nieuwegein, The Netherlands. yakshin@rijnhuizen.nl
authors.forename: A E
authors.initials: AE
authors.lastname: Yakshin
authors.forename: I V
authors.initials: IV
authors.lastname: Kozhevnikov
authors.forename: E
authors.initials: E
authors.lastname: Zoethout
authors.forename: E
authors.initials: E
authors.lastname: Louis
authors.forename: F
authors.initials: F
authors.lastname: Bijkerk
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D015233:Models, Statistical; D055096:Optical Devices; D055095:Optics and Photonics; D010825:Physics / Q000379:methods; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D013499:Surface Properties; D013997:Time Factors