Design of electrostatic phase elements for sorting the orbital angular momentum of electrons

摘要: Abstract The orbital angular momentum (OAM) sorter is a new electron optical device for measuring an electron’s OAM. It based on two phase elements, which are referred to as the “unwrapper” and “corrector” placed in Fourier-conjugate planes microscope. most convenient implementation of this concept use electrostatic such charged needle unwrapper set electrodes with alternating charges corrector. Here, we simulations assess role imperfections device, comparison ideal sorter. We show that finite length boundary conditions introduce astigmatism, leads detrimental cross-talk OAM spectrum. demonstrate improved setup comprising three needles can be used compensate aberration, allowing measurements level spectrum comparable case.