ABSTRACT
The term laser is an acronym composed of the first letters of the words light amplification by stimulated emission of radiation. Physically speaking, radiation is the most basic of these terms. The others are concerned with the mechanism by which lasers produce radiation. We shall discuss these terms in some detail in the material that follows. Most of the discussion will be nonmathematical, resorting to mathematics only when it is important to a basic understanding of laser physics. The statements made are presented without rigorous proof, not to burden the medical reader with a clutter of physical details. By its very nature, an exposition such as this can be neither exhaustive nor encyclopedic. We shall concern ourselves in this chapter with the practical details of only those types of laser most commonly used in surgery today, namely the argon (Ar) ion, the carbon dioxide (CO2), and the neodymium (Nd) yttrium-aluminum-garnet (YAG). However, comprehension of the principles of these lasers will readily enable the reader to grasp the basics of all other lasers currently used in medical applications.
