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Townes later worked with Arthur L. Schawlow to describe the principle of the optical maser, or laser, which Theodore H. Maiman first demonstrated in 1960.
Masers serve as high precision frequency references, for example as an atomic clock. They are also used as electronic amplifiers in radio telescopes.
For more information about frequency reference masers, see atomic clock.
Telescopic masers use arrays of chromium atoms in an insulating aluminium oxide crystal as amplifiers, pumping the energy in at a different radio frequency. That is, they use polished strips of synthetic ruby.
As the input signal comes in, a goldFor alternative meanings, see gold (disambiguation Gold is a chemical element in the periodic table that has the symbol Au ( L. aurum and atomic number 79. A soft, shiny, yellow, heavy, malleable, ductile (trivalent and univalent) transition metal, gold d comb (made of gold because it cannot corrode and change shape) distributes it along the strip of polished ruby. As the radio wave moves through the crystal, it knocks electrons into different orbits. As the electrons wiggle into their new, lower orbits, closer to their atoms' nuclei, they add to the wave that knocked them down. A radioFor other uses see: radio (disambiguation Radio is a technology that allows the transmission of signals by modulation of electromagnetic waves with frequencies below those of light. Radio waves Radio waves are a form of electromagnetic radiation, and are wave is made by a wiggling electric chargeElectric charge is a fundamental property of some subatomic particles, which determines their electromagnetic interactions. It is one of the quantum numbers. Matter that possesses a charge is influenced by, and produces, electromagnetic fields. The intera or magnetic fieldIn physics, a magnetic field is an entity produced by moving electric charges ( electric currents) that exerts a force on other moving charges. The quantum-mechanical spin of a particle produces magnetic fields and is acted on by them as though it were a.
The comb-fingers are spaced so that the desired radio waves add together as they move down the crystal. This means that unwanted radio waves don't add together, and are therefore filtered out.
For cooling, masers use liquid heliumHelium is a colorless, odorless, tasteless chemical element, one of the noble gases of the periodic table of elements. Its boiling and melting points are the lowest among the elements; except in extreme conditions, it exists only as a gas. The second most at a temperature of only about 4 kelvinThe kelvin (symbol: K is the SI unit of temperature, and is one of the seven SI base units. It is defined by two facts: zero kelvin is absolute zero (when molecular motion stops), and one kelvin is the fraction 1/273. 16 of the thermodynamic temperature o. This reduces the noise from electrons, nuclei, and other charged particles that the molecular motion of heat can bounce around.
The electrons are pumped away from their nuclei by longer, ignorable radio waves put onto the ruby from a different comb.
Masers also occur in nature. In interstellar space, water molecules in star-forming regions can undergo a population inversion and emit radiation at 22 GHz, creating the brightest spectral line in the radio universe. Some water masers also emit radiation from a vibrational mode at 96 GHz.
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