the laser beam
Laser stands for Light Amplification by the Stimulated Emission of Radiation. Lasers work by producing an intense beam of bright light that travels in one direction. The laser has the unique ability to produce one specific color or wavelength of light, which can be varied in its intensity and pulse duration. The newest laser systems have become remarkably precise and selective, allowing treatment results and safety levels not previously available. All lasers contain an energized substance that can increase the intensity of light that passes through it. This substance is called the amplifying medium and it can be a solid, a liquid or a gas. Einstein can be considered as the father of the laser. 80 years ago he postulated photons and stimulated emission and won the Nobel Prize for related research on the photoelectric effect. This section discusses the historical evolution from microwave lasers to optical lasers and finally to x-ray lasers and lasers discovered in space. Some theorists were on the right track, especially Planck, who proposed that nature acted by using "quanta" of energy. But it was the young, unknown Albert Einstein who explained everything and started the field of quantum mechanics with his paper on the photo
Advances in technology -- lasers, neutral particle beams, non-nuclear "smart" weapons -- make it possible to attack missiles as they rise. The factor by which the intensity of the light is increased by the amplifying medium is known as the gain. This light is absorbed by atoms or ions within the medium and raises them into higher energy states. Such a laser would have an output beam that is polarized. The mechanism by which this elevates atoms or molecules in the gas to higher energy states depends upon the gas that is being excited and is often complex. In order to increase the intensity of the light, we would need to energize the amplifying medium, or in other terms, pumping. In contrast to the old carbon dioxide lasers, the newest generation of the CO2 laser delivers short bursts of extremely high-energy laser light. Prior to the astronauts arrival on the moon, a mirror has been left in order to judge the distance between the moon and the earth by pulses of laser light aimed at the mirror. The reflection back is then divided by half, just like radar, to find the distance. It depends critically upon the wavelength of the incoming light, the length of the amplifying medium and also upon the extent to which the amplifying medium has been energized. In a helium-neon laser, it is a mixture of the gases helium and neon. An instrument called the iterferometer is used to measure very small changes in distance .
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Acceptance Essays
