The Electromagnetic Field -- Geometrical Optics -- Wave Optics -- Polarization -- Basic Properties of Optical Resonators -- The Fabry Perot Resonator -- Passive Open Resonators -- Stable Resonators -- Resonators on the Stability Limits -- Unstable Resonators -- Resonators with Internal Optical Elements -- Open Resonators with Gain -- The Active Medium -- Output Power of Laser Resonators -- Influence of Gain on Mode Structure and Loss -- Q-switched Laser Resonators -- Resonators with Variable Internal Lenses -- Resonators with Several Active Media -- Misalignment Sensitivity of the Output Power -- Resonators with Internal Nonlinear Elements -- Special Resonator Concepts -- Prism Resonators -- Fourier Transform Resonators -- Hybrid Resonators -- Resonators for Annular Gain Media -- Ring Resonators -- Single Mode Resonators -- Measurement Techniques -- Measurement of Laser Head Parameters -- Measurement of Laser Beam Parameters.Optical Resonators provides a detailed discussion of the properties of optical resonators for lasers from basic theory to recent research. In addition to describing the fundamental theories of resonators such as geometrical optics, diffraction, and polarisation the characteristics of all important resonator schemes and their calculation are presented. Experimental examples, practical problems and a collection of measurement techniques support the comprehensive treatment of the subject. Optical Resonators is the only book currently available that provides a comprehensive overview of the the subject. Combined with the structure of the text and the autonomous nature of the chapters this work will be as suitable for those new to the field as it will be invaluable to specialists conducting research. This second edition has been enlarged by new sections on Q-switching and resonators with internal phase/amplitude control. In addition, the whole book has been brought up-to-date.