A maser is a accessory that produces articular electromagnetic after-effects through addition by angry emission. Historically, “maser” derives from the original, upper-case acronym MASER, which stands for "Microwave Addition by Angry Discharge of Radiation". The lower-case acceptance arose from abstruse development accepting rendered the aboriginal description imprecise, because abreast masers afford EM after-effects (microwave and radio frequencies) beyond a broader bandage of the electromagnetic spectrum; thus, the physicist Charles H. Townes’s appropriate acceptance of “molecular” replacing “microwave”, for abreast linguistic accuracy.1 In 1957, if the optical articular oscillator was aboriginal developed, it was denominated optical maser, but usually alleged laser (Light Addition by Angry Discharge of Radiation), the acronym Gordon Gould accustomed in 1957.
Thursday, February 16, 2012
History
Theoretically, the assumption of the maser was declared by Nikolay Basov and Alexander Prokhorov from Lebedev Institute of Physics at an All-Union Conference on Radio-Spectroscopy captivated by USSR Academy of Sciences in May 1952.
The after-effects were after appear in October 1954. A forerunner of the maser was the aboriginal appearance additional hydrogen accessory congenital and activated by physicists Theodor V. Ionescu and Vasile Mihu in 1946. Independently, Charles H. Townes, J. P. Gordon, and H. J. Zeiger congenital the aboriginal ammonia maser at Columbia University in 1953. The accessory acclimated angry discharge in a beck of activated ammonia molecules to aftermath addition of microwaves at a abundance of 24 gigahertz.
Townes after formed with Arthur L. Schawlow to call the assumption of the optical maser, or laser, which Theodore H. Maiman aboriginal approved in 1960. For their analysis in this acreage Townes, Basov, and Prokhorov were awarded the Nobel Prize in Physics in 1964.
The after-effects were after appear in October 1954. A forerunner of the maser was the aboriginal appearance additional hydrogen accessory congenital and activated by physicists Theodor V. Ionescu and Vasile Mihu in 1946. Independently, Charles H. Townes, J. P. Gordon, and H. J. Zeiger congenital the aboriginal ammonia maser at Columbia University in 1953. The accessory acclimated angry discharge in a beck of activated ammonia molecules to aftermath addition of microwaves at a abundance of 24 gigahertz.
Townes after formed with Arthur L. Schawlow to call the assumption of the optical maser, or laser, which Theodore H. Maiman aboriginal approved in 1960. For their analysis in this acreage Townes, Basov, and Prokhorov were awarded the Nobel Prize in Physics in 1964.
Technology
The maser is based on the assumption of angry discharge proposed by Albert Einstein in 1917. When atoms accept been put into an aflame activity state, they can amplify radiation at the able frequency. By putting such an amplifying average in a beating cavity, acknowledgment is created that can aftermath articular radiation.
edit Some accepted types of masers
Atomic axle masers
Ammonia maser
Free Electron Maser
Hydrogen maser
Gas masers
Rubidium maser
Solid Accompaniment masers
Ruby maser
Whispering Gallery Modes Iron-Sapphire maser
The bifold blue-blooded gas maser is an archetype of a masing average which is nonpolar.2
edit Some accepted types of masers
Atomic axle masers
Ammonia maser
Free Electron Maser
Hydrogen maser
Gas masers
Rubidium maser
Solid Accompaniment masers
Ruby maser
Whispering Gallery Modes Iron-Sapphire maser
The bifold blue-blooded gas maser is an archetype of a masing average which is nonpolar.2
Uses
Masers serve as top attention abundance references. These "atomic abundance standards" are one of the abounding forms of diminutive clocks. They are aswell acclimated as cyberbanking amplifiers in radio telescopes. Masers are getting developed as directed-energy weapons.
edit Hydrogen maser
Main article: Hydrogen maser
A hydrogen maser.
Today, the a lot of important blazon of maser is the hydrogen maser which is currently acclimated as an diminutive abundance standard. Together with added types of diminutive clocks, they aggregate the "Temps Atomique International" or TAI. This is the all-embracing time scale, which is accommodating by the Bureau All-embracing des Poids et Mesures, or BIPM.
It was Norman Ramsey and his colleagues who aboriginal accomplished this device. Today's masers are identical to the aboriginal design. The maser cadence relies on angry acquittal amid two hyperfine levels of diminutive hydrogen. Here is a abrupt description of how it works:
First, a axle of diminutive hydrogen is produced. This is done by appointment the gas at low burden to an RF acquittal (see the account on this page).
The next footfall is "state selection"—in adjustment to get some angry emission, it is all-important to actualize a citizenry antagonism of the atoms. This is done in a way that is actual agnate to the acclaimed Stern-Gerlach experiment. After casual through an breach and a alluring field, abounding of the atoms in the axle are larboard in the top activity akin of the lasing transition. From this state, the atoms can adulteration to the lower accompaniment and afford some bake radiation.
A top superior agency bake atrium borders the microwaves and reinjects them again into the atom beam. The angry acquittal amplifies the microwaves on anniversary canyon through the beam. This aggregate of addition and acknowledgment is what defines all oscillators. The beating abundance of the bake atrium is absolutely acquainted to the hyperfine anatomy of hydrogen: 1420 405 751.768 Hz.
A baby atom of the arresting in the bake atrium is accompanying into a coaxial cable and again beatific to a articular receiver.
The bake arresting advancing out of the maser is actual anemic (a few pW). The abundance of the arresting is anchored and acutely stable. The articular receiver is acclimated to amplify the arresting and change the frequency. This is done application a alternation of phase-locked loops and a top achievement quartz oscillator.
edit Hydrogen maser
Main article: Hydrogen maser
A hydrogen maser.
Today, the a lot of important blazon of maser is the hydrogen maser which is currently acclimated as an diminutive abundance standard. Together with added types of diminutive clocks, they aggregate the "Temps Atomique International" or TAI. This is the all-embracing time scale, which is accommodating by the Bureau All-embracing des Poids et Mesures, or BIPM.
It was Norman Ramsey and his colleagues who aboriginal accomplished this device. Today's masers are identical to the aboriginal design. The maser cadence relies on angry acquittal amid two hyperfine levels of diminutive hydrogen. Here is a abrupt description of how it works:
First, a axle of diminutive hydrogen is produced. This is done by appointment the gas at low burden to an RF acquittal (see the account on this page).
The next footfall is "state selection"—in adjustment to get some angry emission, it is all-important to actualize a citizenry antagonism of the atoms. This is done in a way that is actual agnate to the acclaimed Stern-Gerlach experiment. After casual through an breach and a alluring field, abounding of the atoms in the axle are larboard in the top activity akin of the lasing transition. From this state, the atoms can adulteration to the lower accompaniment and afford some bake radiation.
A top superior agency bake atrium borders the microwaves and reinjects them again into the atom beam. The angry acquittal amplifies the microwaves on anniversary canyon through the beam. This aggregate of addition and acknowledgment is what defines all oscillators. The beating abundance of the bake atrium is absolutely acquainted to the hyperfine anatomy of hydrogen: 1420 405 751.768 Hz.
A baby atom of the arresting in the bake atrium is accompanying into a coaxial cable and again beatific to a articular receiver.
The bake arresting advancing out of the maser is actual anemic (a few pW). The abundance of the arresting is anchored and acutely stable. The articular receiver is acclimated to amplify the arresting and change the frequency. This is done application a alternation of phase-locked loops and a top achievement quartz oscillator.
Astrophysical masers
Maser-like angry discharge aswell occurs in attributes in interstellar space, and is frequently alleged superradiant discharge to analyze it from class masers. Such discharge is empiric from molecules such as baptize (H2O), hydroxyl radicals (OH), booze (CH3OH), formaldehyde (CH2O), and silicon monoxide (SiO). Baptize molecules in star-forming regions can abide a citizenry antagonism and afford radiation at 22 GHz, creating the brightest ashen band in the radio universe. Some baptize masers aswell afford radiation from a vibrational approach at 96 GHz.
Extremely able masers, associated with alive galactic nuclei, are accepted as megamasers and are up to a actor times added able than arch masers.
Extremely able masers, associated with alive galactic nuclei, are accepted as megamasers and are up to a actor times added able than arch masers.
Terminology
The acceptation of the appellation maser has afflicted hardly back its introduction. Initially the acronym was universally accustomed as "microwave addition by angry discharge of radiation," which declared accessories which emitted in the bake arena of the electromagnetic spectrum.
The assumption and abstraction of angry discharge has back been continued to added accessories and frequencies. Thus the aboriginal acronym is sometimes modified, as appropriate by Charles H. Townes,1 to "molecular addition by angry discharge of radiation." Some accept asserted that Townes's efforts to extend the acronym in this way were primarily motivated by the admiration to access the accent of his invention, and his acceptability in the accurate community.3
When the laser was developed, Townes and Schawlow and their colleagues at Bell Labs pushed the use of the appellation optical maser, but this was abundantly alone in favor of laser, coined by their battling Gordon Gould.4 In avant-garde usage, accessories that afford in the X-ray through bittersweet portions of the spectrum are about alleged lasers, and accessories that afford in the bake arena and beneath are frequently alleged masers, behindhand of whether they afford microwaves or added frequencies.
Gould originally proposed audible names for accessories that afford in anniversary allocation of the spectrum, including grasers (gamma ray lasers), xasers (x-ray lasers), uvasers (ultraviolet lasers), lasers (visible lasers), irasers (infrared lasers), masers (microwave masers), and rasers (RF masers). Most of these agreement never bent on, however, and all accept now become (apart from in science fiction) anachronistic except for maser and laser.
The assumption and abstraction of angry discharge has back been continued to added accessories and frequencies. Thus the aboriginal acronym is sometimes modified, as appropriate by Charles H. Townes,1 to "molecular addition by angry discharge of radiation." Some accept asserted that Townes's efforts to extend the acronym in this way were primarily motivated by the admiration to access the accent of his invention, and his acceptability in the accurate community.3
When the laser was developed, Townes and Schawlow and their colleagues at Bell Labs pushed the use of the appellation optical maser, but this was abundantly alone in favor of laser, coined by their battling Gordon Gould.4 In avant-garde usage, accessories that afford in the X-ray through bittersweet portions of the spectrum are about alleged lasers, and accessories that afford in the bake arena and beneath are frequently alleged masers, behindhand of whether they afford microwaves or added frequencies.
Gould originally proposed audible names for accessories that afford in anniversary allocation of the spectrum, including grasers (gamma ray lasers), xasers (x-ray lasers), uvasers (ultraviolet lasers), lasers (visible lasers), irasers (infrared lasers), masers (microwave masers), and rasers (RF masers). Most of these agreement never bent on, however, and all accept now become (apart from in science fiction) anachronistic except for maser and laser.
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