High current efficiency accelerating lens system of field emission scanning electron microscope

Abstract

The current efficiency of the lens system for an accelerating lens composed of three anodes combined with an auxiliary magnetic lens in a field emission scanning electron microscope is described. In this system the spot size for the needed primary beam current can satisfactorily be minimized since the working distance can freely be changed and the auxiliary magnetic lens can be operated under the optimum condition. Current efficiency of one order higher than that of the accelerating lens composed of two anodes is obtained.