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LASER is an acronym for Light Amplification by the Stimulated Emission of Radiation. The concept consists of an excited state atom encountering a photon of the same energy that corresponds to the DE between the excited and ground states of the atom. When such a photon is encountered, it causes the emission of another photon of the same energy. Albert Einstein first suggested this phenomenon in a 1916 paper proving Plank's law of radiation. The idea but it was considered odd and the event of photon interaction with an excited state atom rare. Only much later did scientists begin to create inverted populations with more atoms in the excited state than the ground state so that absorption would not dominate the process and stimulated emission could occur. In 1954, Charles Townes and Arthur Schawlow invented the microwave amplification by stimulated emission of radiation by using ammonia gas and microwave radiation - the maser was invented before the optical laser. The technology is very close but does not use a visible light. In 1958, Charles Townes and Arthur Schawlow thought about a visible laser, an invention that would use infrared or visible spectrum light. Theodore M