Electron energy loss spectroscopy has become an indispensable tool in surface analysis. Although the basic physics of this technique is well understood, instrument design has previously largely been left to intuition. This book is the first to provide a comprehensive treatment of the electron optics involved in the production of intense monochromatic beams and the detection of scattered electrons. It includes a full three-dimensional analysis of the electron optical properties of electron emission systems, monochromators and lens systems, placing particular emphasis on the procedures for matching the various components. The description is kept mathematically simple and focuses on practical aspects, with many hints for writing computer codes to calculate and optimize electrostatic lens elements.