The laser is a device that a beam of light that is both scientifically and practically of great use because it is coherent light. The beam is produced by a




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НазваниеThe laser is a device that a beam of light that is both scientifically and practically of great use because it is coherent light. The beam is produced by a
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The laser is a device that a beam of light that is both scientifically and practically of great use because it is coherent light. The beam is produced by a process known as stimulated emission, and the word "laser" is an acronym for the phrase "light amplification by stimulated emission of radiation."


Light is just like radio waves in the way that it can also carry information. The information is encoded in the beam as variations in the frequency or shape of the light wave. The good part is that since light waves have much higher frequencies they can also hold much more information.


Not only is the particle the smallest light unit but it is a particle as well as a wave. In beams of light whether they are ordinary natural or artificial the photon waves will not be traveling together because they are not being emitted at exactly the same moment but instead at random short bursts. Even if the light is of a single frequency that statement would also be true. A laser is useful because it produces light that is not only of essentially a single frequency but also coherent, with the light waves all moving along in unison.


Lasers consist of several components. A few of the many things that the so-called active medium might consist of are, atoms of a gas, molecules in a liquid, and ions in a crystal. Another component consists of some method of introducing energy into the active medium, such as a flash lamp for example. Another component is the pair of mirrors on either side of the active medium which consists of one that transmits some of the radiation that hits it. If the active component in the laser is a gas laser than each atom is characterized by a set of energy states, or energy levels, of which it may consist. An example of the energy states could be pictured as a unevenly spaced ladder which the higher rungs mean higher states of energy and the lower rungs mean lower states of energy. If left disturbed for a long time the atom will reach its ground state or lowest state of energy. According to quantum mechanics there is only one light frequency that the atom will work with. There are three ways that the atom can deal with the presence of light either it can absorb the light, or spontaneous emission occurs, or stimulated emission occurs. This means that if the atom is at its lowest state that it may absorb the light and jump to its high state and emit extra light while doing so. The second thing it may do is if it is at its highest state it can fall spontaneously to its lower state thus emitting light. The third way is that the atom will jump from its upper state to its lower state thus emitting extra light. Spontaneous emission is not effected by light yet it is rather on a time scale characteristic of the states involved. That is called the spontaneous lifetime. In stimulated emission the frequency of the light is the same as the frequency of the light that stimulated it.


Carbon-monoxide, color center, excimer, free-electron, gas-dynamic, helium-cadmium, hydrogen-fluoride, deuterium-fluoride, iodine, Raman spin-flip, and rare-gas halide lasers are just a few of the many types of lasers there are out there in the world. The helium-neon laser is the most common and by far the cheapest costing about $170. The diode laser is the smallest being packed in a transistor like package. The dye laser are very good for their broad, continuously variable wavelength capabilities.


The theory of stimulated emission was first proved by Albert Einstein in 1916, then population inverse was discussed by V. A. Fabrikant in 1940. This led to the building of the first ammonia maser in 1954 by J. P. Gordon, H. J. Zeiger, and Charles H. Townes. In July of 1960 Theodore H. Maiman announced the generation of a pulse of coherent red light by means of a red crystal- the first laser. In 1987 Gordon Gould won a patent he had been trying to get for three years to build the first gas-discharged laser which he had conceived in 1957. In that same patent the helium-neon was included.


Bibliography:

Bertolotti, M., Masers and lasers: An Historical Approach (1983);

Kasuya, T., and Tsukakoshi, M., Handbook of Laser Science and Technology

(1988); Meyers,Robert, ed., Encyclopedia of Lasers, 3d ed. (1989); Steen, W. M., ed., Lasers in Manufacturing (1989); Whimmery, J. R., ed., Lasers: Invention to Application (1987); Young, M., Optics and Lasers, 3d rev. ed. (1986).


Keywords:


word count laser device that beam light that both scientifically practically great because coherent light beam produced process known stimulated emission word quot laser quot acronym phrase quot light amplification stimulated emission radiation just like radio waves that also carry information information encoded beam variations frequency shape wave good part since waves have much higher frequencies they also hold much more information only particle smallest unit particle well wave beams whether they ordinary natural artificial photon waves will traveling together because they being emitted exactly same moment instead random short bursts even single frequency statement would also true laser useful because produces only essentially single frequency coherent with moving along unison lasers consist several components many things called active medium might consist atoms molecules liquid ions crystal another component consists some method introducing energy into active medium such flash lamp example another component pair mirrors either side active medium which consists transmits some radiation hits component than each atom characterized energy states energy levels which consist example states could pictured unevenly spaced ladder which higher rungs mean higher states lower rungs mean lower left disturbed long time atom will reach ground state lowest state according quantum mechanics there only atom will work with there three ways deal with presence either absorb spontaneous emission occurs stimulated occurs this means lowest state absorb jump high emit extra while doing second thing highest fall spontaneously lower thus emitting third jump from upper thus emitting extra spontaneous effected rather time scale characteristic involved called spontaneous lifetime same carbon monoxide color center excimer free electron dynamic helium cadmium hydrogen fluoride deuterium fluoride iodine raman spin flip rare halide lasers just many types lasers there world helium neon most common cheapest costing about diode smallest being packed transistor like package very good their broad continuously variable wavelength capabilities theory first proved albert einstein then population inverse discussed fabrikant this building first ammonia maser gordon zeiger charles townes july theodore maiman announced generation pulse coherent means crystal first gordon gould patent been trying three years build discharged conceived same patent helium neon included bibliography bertolotti masers historical approach kasuya tsukakoshi handbook science technology meyers robert encyclopedia steen manufacturing whimmery invention application young optics


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