KENBIKYO Vol.52▶No.1 2017

On the Design of Electron Lenses 2

Yoichi Ose and Akira Yonezawa

Abstract: A survey on electron lens designing methods is presented in two consecutive articles. In the first article, we explained the fundamentals of optical design and showed that short focal length was the key strategy to reduce the aberration of the objective lens for high resolution SEMs. Electrostatic and magnetic field complex lenses such as retarding and boosting are effective for short focus length. In this second article, the design simulation procedure of field complex lenses and examples of specific optimization are explained at the beginning. In the latter half, we summarize the technology necessary for mounting magnetic lenses which are the most frequently used for TEMs.

Key words: aberration, simulation, magnetic circuit, magnetic flux density, magnetic saturation