In Waveguide Spectroscopy of Thin Films new methods of study of the linear and nonlinear optical properties of thin films are presented. These techniques are based on the principles of the spatial Fourier spectroscopy of the light beam reflected from a prism-coupling device with the tunnel excitation of guided lightmodes in thin-film structures. Measurement techniques of determination of the absorption coefficient, refractive index and thickness of the dielectric, semiconductor or metallic films are considered. This book is highly recommended for specialists in the fields of integrated and thin film optics and for graduated students in related specialties.There are new techniques of measurement of thin-film parameters stated.