الفهرس 
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Abstract
laser is the acronym for” Light Amplification by Stimulated Emission of Radiation ” . In fact the first amplification of electromagnetic radiation . by stimulated emission employed microwaves in a device called ”MASER” The theoretic foundation of laser action was first postulated by Albert Einstein when he published the” quantum theory of radiation”, in 1919 . Einestein discussed the interaction of atoms, ions, and molecules, and specifically stressed absorption with spontaneous emission of radiation, and proposed another process of atomic interaction , the stimulated emission . Einestein proposed that electromagnetic radiation can be produced by this atomic interaction, which is the basis of Laser energy. the components of LASER acronym will be discussed individually in details. l-LIGHT: Light is a form electromagnetic energy with which man first dealt, because it was visible to the human eye . Originally, the term light included only the visible frequencies. But, invisible light was also found at both ends of the visible spectrum and therfore the term ”Light” includes both the visible and the invisible frequencies. Mer discovery of X--rays and radio waves, light is considered to be a part of a total spectrum of electromagnetic radiation [ EMR]. Based upon the frequency of oscillation of the electromagnetic waves, light is considered to be that part of the electromagnetic spectrum having wavelengths between .