Maser

A maser is a device that produces coherent microwave radiation by amplification through stimulated emission of radiation, the acronym under which it is named. It is used as a highly stable timekeeping element in atomic clocks and as an extremely low-noise microwave amplifier in radio telescopes and deep-space communication ground stations, and it was the direct precursor to the laser, which produces the same kind of coherent radiation at visible wavelengths. The theoretical principle was set out in 1952 by Nikolay Basov and Alexander Prokhorov in the Soviet Union and separately by Joseph Weber at the University of Maryland, and the first working maser, built around energized ammonia molecules, was constructed in 1953 by Charles Townes with James Gordon and Herbert Zeiger at Columbia University. Townes, Basov, and Prokhorov shared the 1964 Nobel Prize in Physics for the work.