This new fourth edition of "Principles of Lasers" is so thoroughly updated and expanded that it is virtually a whole new book. But the text's essential mission remains the same: to provide a wide-ranging yet unified description of laser behavior, physics, technology, and current applications. Dr. Svelto emphasizes the physical rather than the mathematical aspects of lasers, and presents the subject in the simplest terms compatible with a correct physical understanding. Praise for earlier editions: 'Professor Svelto is himself a longtime laser pioneer and his text shows the breadth of his broad acquaintance with all aspects of the field ! Anyone mastering the contents of this book will be well prepared to understand advanced treatises and research papers in laser science and technology' - Arthur L. Schawlow, 1981 Nobel Laureate in Physics. 'Already well established as a self-contained introduction to the physics and technology of lasers! Professor Svelto's book, in this lucid translation by David Hanna, can be strongly recommended for self-study or teaching at the final-year undergraduate or first-year post-graduate levels' - "Physics Bulletin". 'A thorough understanding of this book in conjunction with one of the existing volumes on laser safety will go a long way in providing the health physicist with the understanding he needs! Highly recommended' - "Health Physics". 'Introduces laser science and technology with the accessibility appropriate for the nonspecialist and the enthusiasm of the pioneer' - "Laser Focus". 'A very good introduction to laser theory and practice! aimed at upper-level undergraduate students. It is logically organized and easy to read! Most of the basic mathematical framework needed to understand this evolving field is presented. Every chapter contains a good set of problems, answers to some of which are given in the back' - "Sci-Tech News".