Clay Sanderson, age 14, of Johnson City, Tenn., for his question:
HOW DOES A LASER WORK?
A laser is a device that strengthens or amplifies light. A laser produces a thin beam of light that can burn a hole in a diamond or carry the signals of many different television pictures at the same time.
The word "laser" stands for "light amplification by stimulated emission or radiation."
The light from a laser differs from the light produced by other sources, such as electric bulbs, fluorescent lamps and the sun. The light from these other sources travels in all directions. The light from a laser is highly directional.
Laser light also differs from other light in terms of frequency, which is the number of vibrations of light waves per second. The light from a laser is made up of one or, at the most, a few frequencies. Light from other sources consists of many frequencies.
A laser is an instrument not necessarily larger than a flashlight and it produces an enormously intense, pencil sized and sharply directed beam of light over a long distance.
An important feature of a laser is either a pink ruby crystal containing chromium atoms or a tube of helium and nitrogen gas. A pumping beam of light raises either the chromium atoms or the gases in the tube to a higher energy level. When these atoms return to the lower energy level, they give off radiation all of the same frequency and all in phase.
After being reflected back and forth many times, this amplified beam emerges from the end of the crystal or tube and can be used to transport energy, to accelerate certain chemical reactions or to carry communications signals by reason of the very low level of "noise" in the beam.
The laser may be called an optical "maser." With the pink ruby crystal containing chromium atoms, it is a solid state maser: with the tube of helium and nitrogen, it is a gas maser. The name "maser" comes from "microwave amplification by stimulated emission of radiation."
Lasers were developed during the late 1950s and early 1960s. Laser research grew out of earlier studies of microwave amplifying masers.
Lasers simplify light in much the same way that masers simplify microwaves.
There are three major kinds of lasers based on their light amplifying substances: solid lasers, gas lasers and liquid lasers.
Laser light makes lasers a valuable tool in communications, industry, medicine, military operations and scientific research. A laser can transmit voice messages and television signals. It can be used as a source of intense heat in industry and as a way of removing diseased body tissue in medicine.
Laser guidance devices are also being developed to guide bombs.