title: Advanced double-biprism holography with atomic resolution.
abstract: The optimum biprism position as suggested by Lichte (Ultramicroscopy 64 (1996) 79 [10]) was implemented into a state-of-the-art transmission electron microscope. For a setup optimized for atomic resolution holograms with a width of 30nm and a fringe spacing of 30pm, we investigated the practical improvements on hologram quality. The setup is additionally supplemented by a second biprism as suggested by Harada et al. (Applied Physics Letters 84 (2004) 3229 [12]). In order to estimate the possibilities and limitations of the double biprism setup, geometric optics arguments lead to calculation of the exploitable shadow width, necessary for strong reduction of biprism-induced artefacts. Additionally, we used the double biprism setup to estimate the biprism vibration, yielding the most stable imaging conditions with lowest overall fringe contrast damping. Electron holograms of GaN demonstrate the good match between experiment and simulation, also as a consequence of the improved stability.
authors.affiliation: Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni, 10623 Berlin, Germany. Electronic address: florian.genz@physik.tu-berlin.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Genz
authors.affiliation: Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni, 10623 Berlin, Germany.
authors.forename: Tore
authors.initials: T
authors.lastname: Niermann
authors.affiliation: FEI Company, Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands.
authors.forename: Bart
authors.initials: B
authors.lastname: Buijsse
authors.affiliation: FEI Company, Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands.
authors.forename: Bert
authors.initials: B
authors.lastname: Freitag
authors.affiliation: Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni, 10623 Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Lehmann
keywords: Double biprism; Electron holography; HRTEM; Optimum biprism position