The light beam produced by most lasers is pencil-sized, and maintains its size and direction over very large distances; this sharply focused beam of coherent light is suitable for a wide variety of applications. Lasers have been used in industry for cutting and boring metals and other materials as well as welding and soldering, and for inspecting optical equipment. In medicine, they have been used in surgical operations.
CDs and DVDs read and written to using lasers, and lasers also are employed in laser printers and bar-code scanners. They are used in communications, both in fiber optics and in some space and open-air communications; in a manner similar to radio transmission, the transmitted light beam is modulated with a signal and is received and demodulated some distance away. The field of holography is based on the fact that actual wave-front patterns, captured in a photographic image of an object illuminated with laser light, can be reconstructed to produce a three-dimensional image of the object.
Lasers have been used in a number of areas of scientific research, and have opened a new field of scientific research, nonlinear optics, which is concerned with the study of such phenomena as the frequency doubling of coherent light by certain crystals. One important result of laser research is the development of lasers that can be tuned to emit light over a range of frequencies, instead of producing light of only a single frequency. Lasers also have been developed experimentally as weaponry.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.