KENBIKYO Vol.48▶No.1 2013

Production, Propagation and Interference of Electron Vortex Beam

Koh Saitoh, Yuya Hasegawa and Masaya Uchida

Abstract: In the present paper, we start with a general introduction of electron vortex beam and show our latest results of the production, propagation and interference of electron vortex beams.  We inserted fork-shaped gratings and spiral zone plates, which were nano-fabricated by an FIB instrument, to the illumination lens system of transmission electron microscopes and observed a formation of electron vortex beam with a few nanometers in diameter on the specimen position. Electron vortex beams with a large orbital angular momentum of ℓ=±90ћ were successfully produced by the spiral zone plate. The propagation features show a fairly good agreement with a simulation based on the Fresnel propagation theory. We also performed an interference experiment between two electron vortex beams, and found out that the two electron vortex beams are interfered irrespective of their orbital angular momentum. This result shows that orbital angular momentum of electron, unlike spin angular momentum, is not a simultaneously measurable observable with position and linear momentum.

Key words: electron vortex beam, orbital angular momentum, phase singularity, interference