TY  - JOUR
AU  - Pozzi, Giulio
AU  - Grillo, Vincenzo
AU  - Lu, Peng-Han
AU  - Tavabi, Amir H.
AU  - Karimi, Ebrahim
AU  - Dunin-Borkowski, Rafal E.
TI  - Design of electrostatic phase elements for sorting the orbital angular momentum of electrons
JO  - Ultramicroscopy
VL  - 208
SN  - 0304-3991
CY  - Amsterdam
PB  - Elsevier Science
M1  - FZJ-2020-02662
SP  - 112861 -
PY  - 2020
AB  - The orbital angular momentum (OAM) sorter is a new electron optical device for measuring an electron’s OAM. It is based on two phase elements, which are referred to as the “unwrapper” and “corrector” and are placed in Fourier-conjugate planes in an electron microscope. The most convenient implementation of this concept is based on the use of electrostatic phase elements, such as a charged needle as the unwrapper and a set of electrodes with alternating charges as the corrector. Here, we use simulations to assess the role of imperfections in such a device, in comparison to an ideal sorter. We show that the finite length of the needle and the boundary conditions introduce astigmatism, which leads to detrimental cross-talk in the OAM spectrum. We demonstrate that an improved setup comprising three charged needles can be used to compensate for this aberration, allowing measurements with a level of cross-talk in the OAM spectrum that is comparable to the ideal case.
LB  - PUB:(DE-HGF)16
C6  - pmid:31670053
UR  - <Go to ISI:>//WOS:000500934100003
DO  - DOI:10.1016/j.ultramic.2019.112861
UR  - https://juser.fz-juelich.de/record/878149
ER  -