The laser is one of the most advanced tools we have in our civilization. Lasers are powerful enough to cut through a thick piece of steel, yet can be used in medicine to perform delicate surgery. The inventions of the laser which stands for light amplification by stimulated emission of radiation, can be dated to 1958 with the publication of the scientific paper, "Infrared and Optical Master" by Arthur L. Schawlow. Theodore H. Maiman then built the first laser, a ruby that produced bursts of red light. Maiman first operated his laser in 1960. A laser is a device that creates and amplifies a narrow, intense beam of coherent light. In a laser, the atoms or molecules of a crystal, such as a ruby or garnet --or of a gas, liquid, or other substance -- are excited in what is called the laser cavity so that more of them are at higher energy levels. Reflective surfaces at both ends of the cavity permit energy to reflect back and forth building up in each passage. Lasers now range in size from semiconductor lasers as small as a grain of salt to solid-state and lasers as large as a storage building. The light beam produced by most lasers is pencil-thin and maintains its size and direction over very large distances. Lasers are widely used in industry for cutting and boring metals and other materials, in medicine for surgery, and in communications, scientific research and holography. They are an integral part of such familiar devices as barcode scanners used in super markets, scanners, laser printers, and compact disk players. Since laser beams could easily be adversely affected by atmospheric conditions such as rain fog, low clouds, and objects in the air, such as birds, scientists and engineers suggested a number of novel schemes to protect the light from interference, including shielding it in metal and thermal gas lenses to navigate around bends. It took a major innovation, the development in the early 1970's of hair thin strands of encased glass, called fiber optic waveguides before the laser could transmit telephone signals. Since then, optical fiber has become the medium of choice for telecommunication companies to transmit voice, data, and video. The potential for lasers developed faster in the field of medicine after Kumar Patel invented the carbon dioxide laser which permitted surgeons to perform intricate surgery using photons rather than scalpels; performing operations that a few years ago were almost impossible to perform. Shorter lasers are being used to "weld" detached retinas. Lasers are very important and are becoming more and more advanced. Scientist are still trying to find new ways to harness the power of the laser. Bibliography: Townes, Charles H. How The Laser Happened: Adventures of a Scientist. Oxford University Press, NY, 1999.