The Optics of Round and Multipole Electrostatic Lenses

Abstract

Electrostatic lenses find wide application in many fields of science and technology. Along with the traditional applications, such as cathode-ray devices and input devices in spectrometers, there have been newer areas for their use. In recent years, methods have been devised to probe matter by charged particle beams. This chapter discusses the electrostatic focusing of charged particles. The description is largely restricted to low-intensity beams, when the effect of intrinsic space charge of the beam can be neglected. Both round and astigmatic electron optical lenses are considered in the chapter. The chapter presents the current state of the theory of electrostatic lenses and the application of electrostatic lenses. In the chapter, the methods for field calculation, the theory of focusing, and the aberrations of electrostatic electron lenses are discussed ; recent data on round and quadrupole lenses are presented; and two types of astigmatic lenses, transaxial and crossed ones are discussed in detail. An outline of some new lens types and aberration correctors is also discussed in the chapter.