Computer-Aided-Design of low aberration electrostatic Immersion lens

Abstract

A computerized investigation has been carried out to design an immersion lens with low aberration operating under zero magnification condition using inverse problem. The aberration is highly dependent on the shape of electrodes, for a preassigned electron beam trajectory the paraxial-ray-equation is solved to determine the electrostatic potential and field distribution. From the knowledge of the potential and its first and second derivative the electron optical properties were computed, the electrode geometry was determined from the solution of Laplace equation.