home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
The Epic Interactive Encyclopedia 1998
/
Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
/
M
/
Maser
/
INFOTEXT
< prev
Wrap
Text File
|
1992-09-03
|
959b
|
24 lines
(acronym for microwave amplification by
stimulated emission of radiation) in physics,
a high-frequency microwave amplifier or
oscillator in which the signal to be
amplified is used to stimulate unstable atoms
into emitting energy at the same frequency.
Atoms or molecules are raised to a higher
energy level and then allowed to lose this
energy by radiation emitted at a precise
frequency. The principle has been extended to
other parts of the electromagnetic spectrum
as, for example, in the laser. The two-level
ammonia-gas maser was first suggested in 1954
by C H Townes at Columbia University, New
York, and independently the same year by
Basov and Prokhorov in the USSR. The
solid-state three-level maser, the most
sensitive amplifier known, was envisaged by
Bloembergen in 1956 at Harvard. The ammonia
maser is used as a frequency standard
oscillator (see clock), and the three-level
maser as a receiver for satellite
communications and radioastronomy.