To understand how lasers work we must first understand the physics behind light waves. Light is emitted from a source and travels in straight lines and when it strikes an object is either absorbed, reflected, or refracted. Light behaves primarily like a wave and its this wave nature of light that allows lasers to work. Constructive interference is what amplifies light. Since light is a wave it has a frequency calculated by the equation:

where f is the frequency c is the speed of light which is equal to 3.00 x 108 m/s and is the wave length of light. Also waves have crests, the high points of waves, and troughs, the low points. Constructive interference occurs when two waves of the same frequency meet at a crest or trough therefore combining to form a wave that has an amplitude equal to the sum of the individual amplitudes of the original waves. Stimulated emission is the process that th

The signal strength of laser light can travel long distances with very little reduction in signal strength making lasers ideal for space communication. Laser light can be used for high density information recording allowing it to record and transmit audio and optical information to a radio or monitor. The laser has great importance to the future of communication. Modulated beams of the coherent laser light can transmit a much larger number of messages at a time than the current ordinary telephone systems.

Even more vast than the different types of lasers is the different applications that lasers can be used for. A lasers use is only restricted by the cost to run it and imagination of the user. Lasers are widely used in industry scientific research and medicine, communication, in the military and in every day home uses. In industry lasers are used for their intense heat and precision. Its heat is used for the spot welding of two metals. A focused beam can easily heat, melt or even vaporize a material thus making it useful in any industry. It's used for drilling and cutting gems like diamond by use of a laser drill or laser scriber, to construct and shape machine tools, precisely cut fabrics, synthesize new materials, and to attempt to induce controlled nuclear reactions. A powerful short laser pulse can be used for high speed photography with an exposure time of a few trillionths of a second. Also lasers are used to detect certain types of air pollution and cloud ceilings. High speed laser activated switches are being developed for use inside particle accelerators and these are only a few of the industrial applications.

The military is one of the most vast areas in which lasers play a key roll. Lasers are used in the military for guidance, defense and detection. Innovations such as a laser guidance unit is used to locate or "paint" a target and provide guidance information to a missile or attack unit. Inversely a laser jamming unit is used to direct energy to a hostile attacker to jam or confuse their radar, guidance, tracking, and other devices. A very commonly known detection system is the laser intrusion detector. This is a thin beam that can be placed in entrances so that when broken will alert an intrusion, this device is also used in many commercial and home based alarm systems. Research is currently being done to develop offensive military weapons a concept that has been in the works since the cold war. In March of 1983 President Ronald Regan first proposed the development of an antiballistic missile defense system to provide the United States total protection from nuclear attack. The goal was to intercept incoming missiles in midcourse. This would require advanced technologies some of which were only in the preliminary stage of research. Given the name "Star Wars" the plan required space and ground-based nuclear X-ray lasers, subatomic particle beams and computer-guided projectiles fired by electromagnetic rail guns. Also a network sensors and specialized mirrors for laser targeting would be required. Some of the systems were in development, but some, parti

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Approximate Pages = 8 (250 words per page double spaced)