Axial geometrical aberration correction up to 5th order with N-SYLC

作者：Hoque Shahedul^*; Ito Hiroyuki; Takaoka Akio; Nishi Ryuji

来源：Ultramicroscopy, 2017, 182: 68-80.

DOI：10.1016/j.ultramic.2017.06.014

• Aberration correction
• Sixfold astigmatism
• 5th order spherical aberration
• N-fold symmetric line currents
• Hexapole corrector
• Sextupole corrector

We present N-SYLC (N-fold symmetric line currents) models to correct 5th order axial geometrical aberrations in electron microscopes. In our previous paper, we showed that 3rd order spherical aberration can be corrected by 3-SYLC doublet. After that, mainly the 5th order aberrations remain to limit the resolution. In this paper, we extend the doublet to quadruplet models also including octupole and dodecapole fields for correcting these higher order aberrations, without introducing any new unwanted ones. We prove the validity of our models by analytical calculations. Also by computer simulations, we show that for beam energy of 5 keV and initial angle 10 mrad at the corrector object plane, beam size of less than 0.5 nm is achieved at the corrector image plane.

• 出版日期2017-11