Predicting Optical Properties of an Objective Lens with Aid of Optimization by Synthesis Approach and Simulink Environment

Abstract

In the present research design and simulate magnetic electron lens using optimization by synthesis approach has been achieved. The research in this study may be divided into two parts. The first one is the design part that including the reconstruction process of the pole pieces where a mathematical target function has been used to approximate the distribution of the axial magnetic scalar potential of the symmetrical double polepiece magnetic lens and with the aid of Simulink environment in MATLAB, the target function and its related axial functions have been determined through out of built-up a Simulink Model for each function. By using the analytical solution of Laplace's equation and the distribution of the potential, the polepiece shape of the magnetic lens has been reconstructed according to a specific values of the optimization parameters that affect the design process. The second part is the evaluation of the objective properties of the electron lens that achieved by solving the paraxial ray equation of the electron beam and calculating the aberration coefficients. In addition, a comparison between the present model and the solenoid field model has been achieved. Results of the present research have shown clearly that the followed synthesis optimization approach using Simulink environment in MATLAB is a powerful approach to determine the design of magnetic lenses and can be used to investigate and synthesize other electron-optical devices.