Focusing with Axially Symmetric Fields

Abstract

The most commonly used electron and ion optical elements are the lenses that serve for focusing charged particle beams. These are equivalent to the axially symmetric lenses of light optics, the basic properties of which were introduced in Section 1-4-2. The existence of the electron optical index of refraction (Section 2-6) proves the possibility of producing electron and ion lenses on the basis of the close analogy between light optics and the motion of charged particle beams in electromagnetic fields. The general properties of axially symmetric electrostatic and magnetic fields and the basic methods of their calculation were already treated in Chapter 3. In this chapter a detailed investigation of their focusing properties will be given.