title: Linear chirped slope profile for spatial calibration in slope measuring deflectometry.
abstract: Slope measuring deflectometry is commonly used by the X-ray optics community to measure the long-spatial-wavelength surface figure error of optical components dedicated to guide and focus X-rays under grazing incidence condition at synchrotron and free electron laser beamlines. The best performing instruments of this kind are capable of absolute accuracy on the level of 30-50 nrad. However, the exact bandwidth of the measurements, determined at the higher spatial frequencies by the instrument's spatial resolution, or more generally by the instrument's modulation transfer function (MTF) is hard to determine. An MTF calibration method based on application of a test surface with a one-dimensional (1D) chirped height profile of constant amplitude was suggested in the past. In this work, we propose a new approach to designing the test surfaces with a 2D-chirped topography, specially optimized for MTF characterization of slope measuring instruments. The design of the developed MTF test samples based on the proposed linear chirped slope profiles (LCSPs) is free of the major drawback of the 1D chirped height profiles, where in the slope domain, the amplitude strongly increases with the local spatial frequency of the profile. We provide the details of fabrication of the LCSP samples. The results of first application of the developed test samples to measure the spatial resolution of the BESSY-NOM at different experimental arrangements are also presented and discussed.
authors.affiliation: Helmholtz Zentrum Berlin für Materialien und Energie, Institut für Nanometer Optik und Technologie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Siewert
authors.affiliation: Helmholtz Zentrum Berlin für Materialien und Energie, Institut für Nanometer Optik und Technologie, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Zeschke
authors.affiliation: Leibnitz Institut für Oberflächen Modifizierung Leipzig e.V., IOM, Permoserstr. 15, 04318 Leipzig, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Arnold
authors.affiliation: Leibnitz Institut für Oberflächen Modifizierung Leipzig e.V., IOM, Permoserstr. 15, 04318 Leipzig, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Paetzelt
authors.affiliation: Lawerence Berkeley National Laboratory, Advanced Light Source, 1 Cyclotron Road, Berkeley, California 94720, USA.
authors.forename: V V
authors.initials: VV
authors.lastname: Yashchuk