Focal Length Calculation of Transmission Electron Microscope Magnetic Lenses using CST Particle Studio

In this paper, we have described a method for calculating the focal length of a magnetic lens based on the simulation of the electron path and the magnetic field distribution in the objective lens of transmission electron microscope using CST Particle Studio, an electromagnetic field and electron orbit analysis program. The results of the proposed focal length calculation method are verified by the results of the correlation experiment of the microscope. The magnetic field distribution varies with the focal length and the magnification varies with the focal length. The accuracy of the design method was verified by comparing the maximum magnification measured through simulation and image observations, focusing on the detailed design of the polepiece, and analyzing the effect of pole-piece design parameters on the magnetic lens focal length, among many factors affecting this magnetic field distribution.