ABSTRACT
Laser and light sources offer a potential benefit to many dermatology patients, but the rate of advance within the field can confuse even the experienced laser user without a proper understanding of the principles, which lie behind their use. This chapter highlights some of the most important advances in the medical use of lasers by relating how these advances pertain to basic optical principles. Regardless of the device or dermatologic indication, specific biophysical laws govern how all light affects the skin. The distinction between cosmetic and medical can be arbitrary and is often made by third party payers, but for the purposes of the chapter noncarcinogenic UV-induced effects on the skin and hair removal are considered cosmetic while other indications will fall within either the medical laser section or the ethnic laser section. The interaction of radiation with tissue is governed by three basic processes that can occur when a photon of light reaches the skin: reflection, scattering, and absorption.
