Fundamentals of Lasers for Endoscopy and Laser Tissue Interactions

Abstract

For the past 60 years, surgeons have used high frequency electrical current for cutting and coagulating tissue. With Bovie’s monumental work of the 1920’s (1), the field of electrosurgery was to become yet another achievement of the electrical age. In 1960, Theodore Maiman (2) demonstrated the first optical ‘maser’, later to be dubbed the ‘laser’. Scarcely months later, surgeons were coagulating the retina of the eye and blasting cancerous tumor cells around the laboratory. Each form of energy carries a set of physical properties that need to be understood in order to best develop devices and methods of treatment for medical and surgical practice. Actually, high frequency electrical energy is precisely the same form of energy as that emitted by the laser. Physicists refer to it as electromagnetic (EM) energy or electromagnetic waves. Figure 1.1 is a schematic diagram of the electromagnetic spectrum extending from 0 Hz to 10²¹Hz.