title: Wave-front correction methods for extreme-ultraviolet multilayer reflectors.
abstract: In this theoretical study we show that by removing or depositing additional multilayer (ML) periods of a thin-film interference coating, distortions in the reflected wave front induced by surface figure errors can be corrected. At lambda = 13.4 nm in the extreme-ultraviolet region the removal or deposition of a single period of the standard two-component molybdenum-silicon (Mo/Si) ML interference coating induces an effective phase change of magnitude 0.043pi with respect to an identical optical thickness in vacuum. The magnitude of this wave-front shift can be enhanced with multicomponent MLs optimized for phase change on reflection. We briefly discuss the contributions of the shift in the effective reflection surface of the ML on the phase change. We also predict the feasibility of novel phase-shifting mask for subwavelength imaging applications.
authors.affiliation: Optics Research Group, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
authors.forename: Mandeep
authors.initials: M
authors.lastname: Singh
authors.forename: Matthieu F
authors.initials: MF
authors.lastname: Bal
authors.forename: Joseph J M
authors.initials: JJ
authors.lastname: Braat
authors.forename: Denis
authors.initials: D
authors.lastname: Joyeux
authors.forename: Udo
authors.initials: U
authors.lastname: Dinger