1. High-voltage electricity causes the quartz flash tube to emit an intense burst of light, exciting some of Cr 3+ in the ruby crystal to higher energy levels. 2. At a specific energy level, some Cr 3+ emit photons. At first the photons are emitted in all directions. Photons from one Cr 3+ stimulate emission of photons from other Cr 3+ and the light intensity is rapidly amplified.
3. Mirrors at each end reflect the photons back and forth, continuing this process of stimulated emission and amplification. 4. The photons leave through the partially silvered mirror at one end. This is laser light.
Gain medium : ratio 5:1 mixture of helium and neon gases
Schematic diagram of a dye laser DYE LASER A dye laser can be considered to be basically a four-level system. The energy absorbed by the dye creates a population inversion, moving the electrons into an excited state.
Completely absorbed by water in first few layers of cells – vaporization of surface tissue with little damage to underlying tissue.
Less absorbed by water and beam diffuses through several millimeters – energy is disseminated producing less vaporization and more coagulation (Cooking Effect).
commonly used Laserlights Laser media Color Wavelength (nm) Typical application Carbon dioxide Far infrared 10,600 General, cutting Ruby Red 694 Tattoos, nevi KTP:YAG Green 532 General, pigmented lesions Argon Green 514 Vascular, pigmented lesions Xenon fluoride Ultraviolet 351 Cornea, angioplasty