Modulating Mathematical Function to be used in Electron Objective Lens

Abstract

A theoretical study has been carried out on the magnetic field resulting from a modulating mathematical function to produce a magnetic pole to be used for designing the objective magnetic lens in the electron optical devices. This function has only one effective optimization parameter (a) which is named half of the half-width of the magnetic field that can affect on the design and focal properties of the magnetic lens. At first we will be seen the peak of the magnetic field shifted out of a symmetry point (z=0) by a distance approximately equals to the half half-width of the magnetic field. Therefore, some axial transformations have been carried out to make this peak symmetric around the symmetry axis. The present work has shown the possibly of obtaining a magnetic pole of the magnetic field in which the peak shifted off symmetry point.

Keywords: Electron optics, Objective Magnetic Lenses, Aberration.