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An ion laser is a gas laser which uses an ionized gas as its lasing medium. Like other gas lasers, ion lasers feature a sealed cavity containing the laser medium and mirrors forming a Fabry-Perot resonator. Unlike HeNe lasers, the energy level transitions that contribute to laser action come from ions. Because of the large amount of energy required to excite the ionic transitions used in ion lasers, the required current is much greater, and as a result all but the smallest ion lasers are water cooled. A small air cooled ion laser might produce, for example, 130mW of light with a tube current of 10A @ 105V. This is a total power draw over 1 kW, which translates into a large amount of heat which must be dissipated.
Types of lasers
A mix of argon and krypton can result in a laser with output wavelength appearing as white light.
A krypton laser is an ion laser, a type of gas laser using krypton ions as a gain medium, pumped by electric discharge. Krypton lasers are used for scientific research, or when krypton is mixed with argon, for creation of "white-light" lasers, useful for laser light shows. Krypton lasers are also used in medicine (eg. for coagulation of retina), for manufacture of security holograms, and numerous other purposes.
Krypton lasers emit at several wavelengths through the visible spectrum: at 406.7 nm, 413.1 nm, 415,4 nm, 468.0 nm, 476.2 nm, 482.5 nm, 520.8 nm, 530.9 nm, 568.2 nm, 647.1 nm, 676.4 nm.
The Argon laser was invented in 1964 by William Bridges at Hughes Aircraft and is one of a family of Ion lasers that use a noble gas as the active medium.
Argon lasers are used for retinal phototherapy (for diabetes), lithography, and pumping other lasers. Argon lasers emit at several wavelengths through the visible and ultraviolet spectrum: 351 nm, 454.6 nm, 457.9 nm, 465.8 nm, 476.5 nm, 488.0 nm, 496.5 nm, 501.7 nm, 514.5 nm, 528.7 nm.
Common argon and krypton lasers are capable of emitting continual wave output of several milliwatts to tens of watts continually. Their tubes are usually made of kovar, beryllium oxide ceramics, or copper. In comparison with the helium-neon lasers requiring just a few milliamps, the current used for pumping the krypton laser ranges in several amperes, as the gas has to be ionized. The ion laser tube produces a lot of waste heat and requires active cooling.
Gasses and gas mixtures found in ion lasers
Early switchers used NPN_PNP Pairs, (i.e. American Laser or HGM Medical)
NOTE: A typical Air Cooled Argon Tube needs an equivalent series resistance of ~6 Ohms when running @ 10 amps off 117V power. The plasma in an ion laser, unlike a Helium Neon Laser, has a slightly positive resistance, but will still run away without ballasting. This is why ion laser supplies are very difficult to design. On a large frame laser, the plasma itself has an effective resistance of about -7 Ohms (Spectra Physics 171 Service Manual)
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ion_laser". A list of authors is available in Wikipedia.|