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What is a LASER? A LASER is a special source of light that was invented in the early 60's. The acronym LASER stands for Light Amplification by Stimulated Emmission of Radiation. There are many different types of lasers, ranging in size from several football fields to the size of a single grain of salt. There are gas lasers, such as the Helium-Neon and Argon lasers; solid-state lasers, such as the ruby laser; and Semi-conductor lasers such as the laser diodes that are found in CD and DVD players and your CD-ROM drives. Each has it own method of producing laser light.
LASER's produce light that has very special characteristics: First, the light is monochromatic, or a single wavelength/color. There are LASER's that produce several wavelengths/colors at the same time, but usually the wavelengths are separated and used individually. Second, the light from a LASER is coherent. Coherent light has all of it's waves travelling in sync with one another -- like a "wave train". Third, the light is highly collimated into a beam, which means that it takes a lot of distance to notice any divergence or convergence of the light.
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