Study on the optical properties of the magnetic circuit corner shape of the magnetic lens

He Chen; Quanlin Dong; Pengfei Wang; Lixin Zhang

doi:10.1016/j.ultramic.2018.09.007

Study on the optical properties of the magnetic circuit corner shape of the magnetic lens

Ultramicroscopy. 2018 Dec:195:147-156. doi: 10.1016/j.ultramic.2018.09.007. Epub 2018 Sep 13.

Authors

He Chen¹, Quanlin Dong², Pengfei Wang¹, Lixin Zhang¹

Affiliations

¹ School of Instrumentation Science and Opto-electroics Engineering, Beihang University, China; Key Laboratory of Micro-Nano Measurement-Manipulation and Physics, China.
² School of Instrumentation Science and Opto-electroics Engineering, Beihang University, China; Key Laboratory of Micro-Nano Measurement-Manipulation and Physics, China. Electronic address: dongquanlin@buaa.edu.cn.

PMID: 30273902
DOI: 10.1016/j.ultramic.2018.09.007

Abstract

In this paper, we aim to improve the optical properties of magnetic lenses in transmission electron microscope(TEM). First, the mathematical model of the magnetic field is established, and the formula of the reluctance of the magnetic lens at the corner of the magnetic circuit is deduced. The calculation results of the reluctance are obtained by the numerical analysis method. Then, we find that the corner reluctance affects the density distribution of the magnetic flux lines at the corner. Therefore, the structural shape of the corner of the magnetic lens is optimized. The magnetic flux density on optical axis and the corresponding electron optical parameters are obtained by calculations and simulations. The optical properties of the magnetic lens are improved after the optimization.

Keywords: Corner reluctance; Focal length; Magnetic flux density on the axis; Magnetic lens.