Lasers and related technologies

Abstract

When Albert Einstein fi rst developed the concept of laser radiation in The Quantum Theory of Radiation, none could have predicted all its future roles in the applied sciences [1] Since that time, physicians have used lasers along with other components of the electromagnetic spectrum in a variety of medical and cosmetic applications. In part because of accessibility, many of these developments have involved the skin and eyes. Appreciation of the physics behind lasers provides a foundation for understanding its applications. The electromagnetic spectrum comprises radiation energy spanning short gamma waves to long radio waves and includes X-rays, ultraviolet radiation, visible light, infrared light, and microwaves in between. If suffi cient electromagnetic radiation is absorbed by resting atoms, their electrons are stimulated to excited states.