This second edition, appearing about twenty years after the discovery of the laser is a substantially revised version of the first edition. It is, like the first, aimed at both classroom teaching and self-study by technical personnel interested in learning the principles of laser operation. In preparing the second edition the hope has been that both these aims will be better served as a result of the various improvements made. The main changes have been made with the following aims in mind: (i) To update the book. Thus new topics have been added (in particular on various new types of lasers, e. g. , rare-gas-halide excimer lasers, color-center lasers, and free-electron lasers), while on the other hand some topics have been given less emphasis (again this applies particularly to some types of lasers, e. g. , the ruby laser). Updating is especially important in the area of laser applications, and the chapter on this topic has therefore been com­ pletely rewritten. (ii) To make some improvements to the logical consis­ tency of the book by rearranging material and adding new material. Thus a few topics have been moved from one section to another and a new chapter entitled Laser Beam Transformation has been added. (iii) To further reduce the mathematical content, placing greater emphasis on physical descrip­ tions of phenomena.

1 Introductory Concepts.- 1.1 Spontaneous and Stimulated Emission, Absorption.- 1.2 The Laser Idea.- 1.3 Pumping Schemes.- 1.4 Properties of Laser Beams.- Problems.- 2 Interaction of Radiation with Matter.- 2.1 Summary of Blackbody Radiation Theory.- 2.2 Absorption and Stimulated Emission.- 2.3 Spontaneous Emission.- 2.4 Nonradiative Decay.- 2.5 Line Broadening Mechanisms.- 2.6 Saturation.- 2.7 Degenerate Levels.- 2.8 Relation between Cross Section and Spontaneous Radiative Lifetime.- 2.9 Molecular Systems.- Problems.- References.- 3 Pumping Processes.- 3.1 Introduction.- 3.2 Optical Pumping.- 3.3 Electrical Pumping.- Problems.- References.- 4 Passive Optical Resonators.- 4.1 Introduction.- 4.2 Plane-Parallel Resonator.- 4.3 Confocal Resonator.- 4.4 Generalized Spherical Resonator.- 4.5 Unstable Resonators.- Problems.- References.- 5 Continuous Wave and Transient Laser Behavior.- 5.1 Introduction.- 5.2 Rate Equations.- 5.3 CW Laser Behavior.- 5.4 Transient Laser Behavior.- 5 5 Limits to the Rate Equations.- Problems.- References.- 6 Types of Lasers.- 6.1 Introduction.- 6.2 Solid-State Lasers.- 6.3 Gas Lasers.- 6.4 Liquid Lasers (Dye Lasers).- 6.5 Chemical Lasers.- 6.6 Semiconductor Lasers.- 6.7 Color-Center Lasers.- 6.8 The Free-Electron Laser.- 6.9 Summary of Performance Data.- Problems.- References.- 7 Properties of Laser Beams.- 7.1 Introduction.- 7.2 Monochromaticity.- 7.3 First-Order Coherence.- 7.4 Directionality.- 7.5 Laser Speckle.- 7.6 Brightness.- 7.7 Higher-Order Coherence.- Problems.- References.- 8 Laser Beam Transformation.- 8.1 Introduction.- 8.2 Transformation in Space. Gaussian Beam Propagation.- 8.3 Transformation in Amplitude: Laser Amplification.- 8.4 Transformation in Frequency: Second-Harmonic Generation and Parametric Oscillation.- Problems.- References.- 9 Applications of Lasers.- 9.1 Introduction.- 9.2 Applications in Physics and Chemistry.- 9.3 Applications in Biology and Medicine.- 9.4 Material Working.- 9.5 Optical Communications.- 9.6 Measurement and Inspection.- 9.7 Thermonuclear Fusion.- 9.8 Information Processing and Recording.- 9.9 Military Applications.- 9.10 Holography.- 9.11 Concluding Remarks.- References.- Appendixes.- A Space-Dependent Rate Equations.- B Physical Constants.- Answers to Selected Problems.