Alan Wilcox, age 12, of Visalia, California, for his question:
What exactly is laser light?
A slim laser beam could travel straight to the moon and illumine a small circle on its surface. Traveling through the same distance, a beam of ordinary light would spread out through a large volume of space. Ordinary light spreads out from its source, which makes its intensity diminish with distance at a set ratio. The laser is designed to concentrate light in parallel lines, so that it does not fan apart and diminish its intensity.
After many centuries, scientists finally fathomed the nature of ordinary white light. Then the really interesting investigations began. Researchers began trying to improve it, or at least to make it behave in different ways. They hoped to concentrate a spreading beam of light in slim straight lines. In the 1960s, they succeeded in creating the laser beam and more amazing lasers arrived later. All of them are tight beams of concentrated light traveling in straight lines.
Ordinary light is a vast assortment of wave lengths, or energy frequencies, pulsing along at 186,000 miles per second. It fans out from its source in all directions and its multiple frequencies are disturbed by all sorts of outside interferences. When refracted, they reveal the colors of the spectrum. The almost parallel laser beam limits the number of frequencies and its light is always the same color.
The first lasers were short spurts of red light from ruby crystals inside complicated quartz tubes. In later models, gaseous mixtures were used to emit continuous beams. A power source is turned on to energize the captured atoms and molecules. Some of their excited energy emits light. When this light interacts with other excited atoms, they too release light energy. This complex involvement is called "stimulated emissions." It is different from ordinary light because it has only one color and its selected frequencies all travel in the same direction.
A slim laser beam can be focused on an area no bigger than a living cell. This makes it useful for delicate eye surgery. Another type can concentrate its intensified energy to create temperatures as high as 10,004 degrees Fahrenheit. This makes it useful for unlimited specialized duties in industries. Hocaever, a far greater future awaits the laser in the realm of communications. The sprawling frequencies of ordinary radio are prone to distortions by local and long distance interferences, Laser beams do not have these problems.
This particular field of science is called Light Amplification by Stimulated Emissions of Radiation. If you gather up the capital letters and arrange them in the right order, you can see how the amazing laser got its name.