An acronym for "microwave amplification by stimulated emission of radiation." The first operational maser was constructed by Townes Eric Weisstein's World of Biography in 1954. This device, when pumped with a weak microwave beam, produced a cascade of transitions in ammonia molecules, reinforcing the beam. This device was the forerunner of the laser, invented by Maiman Eric Weisstein's World of Biography in 1960. The first continuous maser was designed by Bloembergen Eric Weisstein's World of Biography (1956). Masers have subsequently been detected in space, and several hundred were known as of 1995.
References
Bertolotti, M. Masers and Lasers: An Historical Approach. Bristol: A. Hilger, 1983.
Bloembergen, N. Phys. Rev. 104, 324, 1956.
Gordon, J. P.; Zeiger, H. J.; and Townes, C. H. Phys. Rev. 95, 282, 1954.
Klein, A. Masers and Lasers. 1971.
Talbot, J. "Microwave Laser." http://www.achilles.net/~jtalbot/history/ammonia.html.
Talbot, J. "Naturally Occurring Microwave Lasers." http://www.achilles.net/~jtalbot/history/hydroxyl.html.
Weisstein, E. W. "Books about Lasers." http://www.ericweisstein.com/encyclopedias/books/Lasers.html.
