title: Design and implementation of a micron-sized electron column fabricated by focused ion beam milling.
abstract: We have designed, fabricated and tested a micron-sized electron column with an overall length of about 700 microns comprising two electron lenses; a micro-lens with a minimal bore of 1 micron followed by a second lens with a bore of up to 50 microns in diameter to shape a coherent low-energy electron wave front. The design criteria follow the notion of scaling down source size, lens-dimensions and kinetic electron energy for minimizing spherical aberrations to ensure a parallel coherent electron wave front. All lens apertures have been milled employing a focused ion beam and could thus be precisely aligned within a tolerance of about 300 nm from the optical axis. Experimentally, the final column shapes a quasi-planar wave front with a minimal full divergence angle of 4 mrad and electron energies as low as 100 eV.
authors.affiliation: Physics Department, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. Electronic address: flavio.wicki@physik.uzh.ch.
authors.forename: Flavio
authors.initials: F
authors.lastname: Wicki
authors.affiliation: Physics Department, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Longchamp
authors.affiliation: Physics Department, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Conrad
authors.initials: C
authors.lastname: Escher
authors.affiliation: Physics Department, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
authors.forename: Hans-Werner
authors.initials: HW
authors.lastname: Fink
keywords: Coherent diffraction; Electron lens; Electron optics; Imaging; Low-energy electrons