What is a laser?

What is a laser?

The word laser is an acronym, which stands for light amplification by stimulated emission of radiation. A laser differs from natural light in three ways:

·        Lasers emit intense parallel beams of single-frequency radiation (light). Natural light disperses widely as it travels.

·  Laser light is essentially monochromatic. Natural light contains a wide spectrum of wavelengths.

·  Laser light is coherent and its photons oscillate synchro-nously. In natural light the photons oscillate randomly.

A laser system is composed of four different parts:

·  The first part is the laser medium, which may be a gas, liquid, or solid. In solid medium lasers, ionic impurities known as dopants are used to generate the laser light. An example of a laser with a dopant is the neodymium-yttrium-aluminum-garnet (Nd-YAG) laser. The dopant determines the wavelength of the emitted radiation.

·  The second portion is the optical cavity wherein the laser medium is confined. One of the mirrors in the optical cavity allows the laser beam to escape the cavity instead of being reflected by the other mirrors.

·  The third portion of the laser system is a pumping source, which supplies electrical discharge or high-energy photons from a xenon flash lamp.

·  The fourth portion is a light guide, which directs the laser beam to the site of surgery.