ELECTRON OPTICAL SYSTEMS WITH FIXED IMAGE POSITIONS FOR BEAMS OF VARIABLE ENERGY.

Two electrostatic electron optical systems are discussed. The first system is based upon the known parameters of a double aperture lens and the second is an empirical design. Experimental results are presented which show that it is possible to operate these two systems in such a way that, with a constant position and energy of the initial object, the position of the final image can be kept very nearly constant when the energy of the electrons forming the image varies over a wide range.