title: Confocal soft X-ray scanning transmission microscopy: setup, alignment procedure and limitations.
abstract: Zone-plate-based scanning transmission soft X-ray microspectroscopy (STXM) is a well established technique for high-contrast imaging of sufficiently transparent specimens (e.g. ultrathin biological tissues, polymer materials, archaeometric specimens or magnetic thin films) with spatial resolutions in the regime of 20 nm and high spectroscopic or chemical sensitivity. However, due to the relatively large depth of focus of zone plates, the resolution of STXM along the optical axis so far stays unambiguously behind for thicker X-ray transparent specimens. This challenge can be addressed by the implementation of a second zone plate in the detection pathway of the beam, resulting in a confocal arrangement. Within this paper a first proof-of-principle study for a confocal STXM (cSTXM) and an elaborate alignment procedure in transmission and fluorescence geometry are presented. Based on first confocal soft X-ray micrographs of well known specimens, the advantage and limitation of cSTXM as well as further development potentials for future applications are discussed.
authors.affiliation: Physikalische Chemie II and ICMM, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Egerlandstraße 3, 91058 Erlangen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Späth
authors.affiliation: Swiss Light Source, Paul Scherrer Institut, 5232 Villigen, Switzerland.
authors.forename: Jörg
authors.initials: J
authors.lastname: Raabe
authors.affiliation: Physikalische Chemie II and ICMM, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Egerlandstraße 3, 91058 Erlangen, Germany.
authors.forename: Rainer H
authors.initials: RH
authors.lastname: Fink
keywords: STXM; confocal microscopy; soft X-ray microscopy; zone plate