Ellipsometry is a unique optical technique of great sensitivity for in situ non-destructive characterization of surface (inter-facial) phenomena (reactions) utilizing the change in the state of polarization of a light-wave probe. Although known for almost a century, the use of ellipsometry has increased rapidly in the last two decades. Among the most significant recent developments are new applications, novel and automated instrumentation and techniques for error-free data analysis. This book provides the necessary analytical and experimental tools needed for competent understanding and use of these developments. It is directed to those who are already working in the field and, more importantly, to the newcomer who would otherwise have to sift through several hundred published papers. The authors first present a comprehensive study of the different mathematical representations of polarized light and how such light is processed by optical systems, going on to show how these tools are applied to the analysis of ellipsometer systems. To relate ellipsometric measurements to surface properties, use is then made of electromagnetic theory. Experimental techniques and apparatus are described and the many interesting applications of ellipsometry to surface and thin-film phenomena are reviewed. This reference work is addressed to researchers and students with a strong interest in surface and thin-film physics and optics and their applications. It is a must for libraries in the fields of solid state physics, physical chemistry, electro-chemistry, metallurgy and optical engineering.