Study on combined immersion electrostatic-magnetic focusing lenses without crossovers

Wide electron beam focusing properties of combined immersion electrostatic-magnetic focusing system are studied; their curvilinear axis aberration coefficients are derived. Based upon ray tracing method and curvilinear axis theory of wide electron beam systems, a program was written and as an example, a practical structure of the lens is numerically simulated. The computed results show that demagnified images with high resolution of tens of nanometers can be obtained for an object field size in millimeter range.