π/2 mode converters and vortex generators for electrons

C Kramberger; S Löffler; T Schachinger; P Hartel; J Zach; P Schattschneider

doi:10.1016/j.ultramic.2019.05.003

π/2 mode converters and vortex generators for electrons

Ultramicroscopy. 2019 Sep:204:27-33. doi: 10.1016/j.ultramic.2019.05.003. Epub 2019 May 17.

Authors

C Kramberger¹, S Löffler², T Schachinger³, P Hartel⁴, J Zach⁴, P Schattschneider⁵

Affiliations

¹ Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10/E138, Wien 1040, Austria. Electronic address: c.kramberger@gmail.com.
² Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10/E138, Wien 1040, Austria; University Service Center for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10/E057-02, Wien 1040, Austria.
³ University Service Center for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10/E057-02, Wien 1040, Austria.
⁴ CEOS Corrected Electron Optical Systems GmbH, Englerstraße 28, Heidelberg 69126, Germany.
⁵ Institute of Solid State Physics, TU Wien, Wiedner Hauptstraße 8-10/E138, Wien 1040, Austria; University Service Center for Transmission Electron Microscopy, TU Wien, Wiedner Hauptstraße 8-10/E057-02, Wien 1040, Austria. Electronic address: peter.schattschneider@tuwien.ac.at.

PMID: 31125763
DOI: 10.1016/j.ultramic.2019.05.003

Abstract

In optics, mode conversion is an elegant way to switch between Hermite Gaussian and Laguerre Gaussian beam profiles and thereby impart orbital angular momentum onto the beam and to create vortices. In optics such vortex beams can be produced in a setup consisting of two identical cylinder lenses. In electron optics, quadrupole lenses can be used for the same purpose. Here we investigate generalized asymmetric designs of a quadrupole mode converter that may be realized within the constraints of existing electron microscopes and can steer the development of dedicated vortex generators for high brilliance electron vortex probes of atomic scale.

Keywords: Electron microscopy; Mode conversion; Orbital angular momentum; Vortex beams.