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A concentrated light beam of only one wavelength. Regular white light is emits many different wavelengths. The word LASER is actually an acronym for Light Amplification by Stimulated Emission of Radiation. Laser light is coherent, monochromatic, and directional. In other words, the photons emitted by the laser are traveling in coordination, the light is of one color, and the light is concentrated and travels in a tight beam (whereas normal light sources release light that travels in many directions). Concave mirrors are used to concentrate the laser light. The mirrors bounce the light between them to create a single beam, which is then focused onto an object. Lasers are very useful to the printing industry for imaging plates digitally. All lasers have three basic components: a pumping source, a lasing medium, and a resonator. The pumping source is a device that feeds the energy to the laser. The lasing medium is an active medium that is able to absorb the energy from the pumping source and re-emit the energy as laser light. The resonator is a device that amplifies the light to produce the laser beam (such as the concave mirrors used to concentrate the laser light). A laser is usually described by the type of lasing medium that is used. A gas laser uses a gas, such as helium, as the lasing medium; a liquid laser uses a special liquid; a semiconductor laser uses semiconductor materials; and so on.
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