THE PHYSICAL CHARACTERISTICS OF A SMALL SPHERICAL ABERRATION SEPTIER S ELECTROSTATIC LENS FOR ELECTRON OR ION BEAM FOCUSING

As a small spherical aberration eleetrostatic lens Septier s lens has been proved to be an almost ideal structure by a number of experiments. This paper provides a meth-od of calculating all the physical characteristics of Septier s electrostatic lens. It also provides the calculated results at various geometrie sizes and voltages; they are useful for making correct choice under different conditions.