The word laser stands for Light Amplification by the Stimulated Emission of Radiation. Laser light is made by feeding energy, such as light or electricity, into a substance called the active medium. As the active medium takes up the energy, its atoms release light of a particular wavelength. When light from one atom strikes its neighboring atoms they also start to release identical bursts of light. This light builds up as it is reflected to and fro by special mirrors at each end of the laser. Eventually, the light becomes so intense that some of it escapes through an opening in one of the mirrors and forms a laser beam.

In 1960, Theodore Maiman, an American engineer and physicist, built the first working laser. The device, which was only as long as a match, generated laser light by energizing a ruby crystal with light from a camera-type flash tube.

Today, high-powered industrial lasers may fill whole rooms. Their long wavelengths produce intense heat that can easily cut through solid metals.

Lower-powered lasers are used in medicine to cut through body parts, especially in delicate surgery such as inside the eyes. The heat of the laser beam seals blood vessels.

© 2007 Al Bawaba (www.albawaba.com)