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Ion laser

January 01, 1970

An ion laser is a gas laser that uses an ionized gas as its lasing medium.[1] Like other gas lasers, ion lasers feature a sealed cavity containing the laser medium and mirrors forming a Fabry–Pérot resonator. Unlike helium–neon 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 almost all except for the smallest ion lasers are water-cooled. A small air-cooled ion laser might produce, for example, 130 milliwatts of output light with a tube current of about 10 amperes and a voltage of 105 volts. Since one ampere times one volt is one watt, this is an electrical power input of about one kilowatt. Subtracting the (desirable) light output of 130 mW from power input, this leaves the large amount of waste heat of nearly one kW. This has to be dissipated by the cooling system. In other words, the power efficiency is very low.

1 mW Uniphase HeNe on alignment rig (left) and 2 W Lexel 88 argon-ion laser (center) with power-supply (right). To the rear are hoses for water cooling.

Types edit

Krypton laser edit

A krypton laser is an ion laser using ions of the noble gas krypton as its gain medium. The laser pumping is done by an electrical discharge. Krypton lasers are widely used in scientific research, and in commercial uses, when the krypton is mixed with argon, it creates a "white-light" lasers, useful for laser light shows. Krypton lasers are also used in medicine (e.g. for coagulation of retina), for the manufacture of security holograms, and numerous other purposes.

Krypton lasers can emit visible light close to several different wavelengths, commonly 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, and 676.4 nm.

Argon laser edit

 
This argon-ion laser emits blue–green light at 488 and 514 nm

The argon-ion laser was invented in 1964 by William Bridges at the Hughes Aircraft Company[2] and it is one of the family of ion lasers that use a noble gas as the active medium.

Argon-ion lasers are used for retinal phototherapy (for the treatment of diabetes), lithography, and the pumping of other lasers. Argon-ion lasers emit at 13 wavelengths through the visible and ultraviolet spectra, including: 351.1 nm, 363.8 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, and 1092.3 nm.[3] However, the most commonly used wavelengths are in the blue–green region of the visible spectrum. These wavelengths have the potential for use in underwater communications because seawater is quite transparent in this range of wavelengths.

 
An argon-laser beam consisting of multiple colors (wavelengths) strikes a silicon diffraction mirror grating and is separated into several beams, one for each wavelength (left to right): 458 nm, 476 nm, 488 nm, 497 nm, 502 nm, and 515 nm

Common argon and krypton lasers are capable of emitting continuous-wave (CW) output of several milliwatts to tens of watts. Their tubes are usually made from nickel end bells, kovar metal-to-ceramic seals, beryllium oxide ceramics, or tungsten disks mounted on a copper heat spreader in a ceramic liner. The earliest tubes were simple quartz, then followed by quartz with graphite disks. In comparison with the helium–neon lasers, which require just a few milliamperes of input current, the current used for pumping the argon laser is several amperes, since the gas has to be ionized. The ion laser tube produces much waste heat, and such lasers require active cooling.

The typical noble-gas ion-laser plasma consists of a high-current-density glow discharge in a noble gas in the presence of a magnetic field. Typical continuous-wave plasma conditions are current densities of 100 to 2000 A/cm2, tube diameters of 1.0 to 10 mm, filling pressures of 0.1 to 1.0 Torr (0.0019 to 0.019 psi), and an axial magnetic field of the order of 1000 gauss.[4]

William R. Bennett, a co-inventor of the first gas laser (the helium–neon laser), was the first to observe spectral hole burning effects in gas lasers, and he created the theory of "hole burning" effects in laser oscillation. He was co-discoverer of lasers using electron-impact excitation in each of the noble gases, dissociative excitation transfer in the neon–oxygen laser (the first chemical laser), and collision excitation in several metal-vapor lasers.

Other commercially available types edit

  • Ar/Kr: A mix of argon and krypton can result in a laser with output wavelengths that appear as white light.
  • Helium–cadmium: blue laser emission at 442 nm and ultraviolet at 325 nm.
  • Copper vapor: yellow and green emission at 578 nm and 510 nm.

Experimental edit

Applications edit

See also edit

References edit

  1. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "ion laser". doi:10.1351/goldbook.I03219
  2. ^ W. B. Bridges, "LASER OSCILLATION IN SINGLY IONIZED ARGON IN THE VISIBLE SPECTRUM", Appl. Phys. Lett. 4, 128–130 (1964).
  3. ^ "Lexel Laser is under construction".
  4. ^ Bridges, Halstead et al., Proceedings of the IEEE, 59 (5). pp. 724–739.
  5. ^ Hoffman Toschek, et al., "The Pulsed Xenon Ion Laser: Covers the UV, visible, and near-IR with optics changes", IEEE Journal of Quantum Electronics
  6. ^ Hattori, Kano, Tokutome and Collins, "CW Iodine Ion Laser in a Positive Column Discharge", IEEE Journal of Quantum Electronics, June 1974
  7. ^ Cold Cathode Pulsed Gas Laser" by R. K. Lomnes and J. C. W. Taylor in: Review of Scientific Instruments, vol 42, no. 6, June, 1971.
  8. ^ F. J. Duarte and L. W. Hillman (Eds.), Dye Laser Principles (Academic, New York, 1990) Chapters 3 and 5

January 01, 1970
laser, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, september, 2007, lea. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Ion laser news newspapers books scholar JSTOR September 2007 Learn how and when to remove this message An ion laser is a gas laser that uses an ionized gas as its lasing medium 1 Like other gas lasers ion lasers feature a sealed cavity containing the laser medium and mirrors forming a Fabry Perot resonator Unlike helium neon 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 almost all except for the smallest ion lasers are water cooled A small air cooled ion laser might produce for example 130 milliwatts of output light with a tube current of about 10 amperes and a voltage of 105 volts Since one ampere times one volt is one watt this is an electrical power input of about one kilowatt Subtracting the desirable light output of 130 mW from power input this leaves the large amount of waste heat of nearly one kW This has to be dissipated by the cooling system In other words the power efficiency is very low 1 mW Uniphase HeNe on alignment rig left and 2 W Lexel 88 argon ion laser center with power supply right To the rear are hoses for water cooling Contents 1 Types 1 1 Krypton laser 1 2 Argon laser 1 3 Other commercially available types 1 4 Experimental 2 Applications 3 See also 4 ReferencesTypes editKrypton laser edit A krypton laser is an ion laser using ions of the noble gas krypton as its gain medium The laser pumping is done by an electrical discharge Krypton lasers are widely used in scientific research and in commercial uses when the krypton is mixed with argon it creates a white light lasers useful for laser light shows Krypton lasers are also used in medicine e g for coagulation of retina for the manufacture of security holograms and numerous other purposes Krypton lasers can emit visible light close to several different wavelengths commonly 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 and 676 4 nm Argon laser edit nbsp This argon ion laser emits blue green light at 488 and 514 nm The argon ion laser was invented in 1964 by William Bridges at the Hughes Aircraft Company 2 and it is one of the family of ion lasers that use a noble gas as the active medium Argon ion lasers are used for retinal phototherapy for the treatment of diabetes lithography and the pumping of other lasers Argon ion lasers emit at 13 wavelengths through the visible and ultraviolet spectra including 351 1 nm 363 8 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 and 1092 3 nm 3 However the most commonly used wavelengths are in the blue green region of the visible spectrum These wavelengths have the potential for use in underwater communications because seawater is quite transparent in this range of wavelengths nbsp An argon laser beam consisting of multiple colors wavelengths strikes a silicon diffraction mirror grating and is separated into several beams one for each wavelength left to right 458 nm 476 nm 488 nm 497 nm 502 nm and 515 nm Common argon and krypton lasers are capable of emitting continuous wave CW output of several milliwatts to tens of watts Their tubes are usually made from nickel end bells kovar metal to ceramic seals beryllium oxide ceramics or tungsten disks mounted on a copper heat spreader in a ceramic liner The earliest tubes were simple quartz then followed by quartz with graphite disks In comparison with the helium neon lasers which require just a few milliamperes of input current the current used for pumping the argon laser is several amperes since the gas has to be ionized The ion laser tube produces much waste heat and such lasers require active cooling The typical noble gas ion laser plasma consists of a high current density glow discharge in a noble gas in the presence of a magnetic field Typical continuous wave plasma conditions are current densities of 100 to 2000 A cm2 tube diameters of 1 0 to 10 mm filling pressures of 0 1 to 1 0 Torr 0 0019 to 0 019 psi and an axial magnetic field of the order of 1000 gauss 4 William R Bennett a co inventor of the first gas laser the helium neon laser was the first to observe spectral hole burning effects in gas lasers and he created the theory of hole burning effects in laser oscillation He was co discoverer of lasers using electron impact excitation in each of the noble gases dissociative excitation transfer in the neon oxygen laser the first chemical laser and collision excitation in several metal vapor lasers Other commercially available types edit Ar Kr A mix of argon and krypton can result in a laser with output wavelengths that appear as white light Helium cadmium blue laser emission at 442 nm and ultraviolet at 325 nm Copper vapor yellow and green emission at 578 nm and 510 nm Experimental edit Xenon 5 Iodine 6 Oxygen 7 Applications editConfocal laser scanning microscopy Surgical Laser medicine High speed typesetters Laser light shows DNA sequencers Spectroscopy experiments Pumping dye lasers 8 Semiconductor wafer inspection Direct write high density PCB lithography Fiber Bragg Grating production Long coherence length models can be used for holography See also editLaser List of laser typesReferences edit IUPAC Compendium of Chemical Terminology 2nd ed the Gold Book 1997 Online corrected version 2006 ion laser doi 10 1351 goldbook I03219 W B Bridges LASER OSCILLATION IN SINGLY IONIZED ARGON IN THE VISIBLE SPECTRUM Appl Phys Lett 4 128 130 1964 Lexel Laser is under construction Bridges Halstead et al Proceedings of the IEEE 59 5 pp 724 739 Hoffman Toschek et al The Pulsed Xenon Ion Laser Covers the UV visible and near IR with optics changes IEEE Journal of Quantum Electronics Hattori Kano Tokutome and Collins CW Iodine Ion Laser in a Positive Column Discharge IEEE Journal of Quantum Electronics June 1974 Cold Cathode Pulsed Gas Laser by R K Lomnes and J C W Taylor in Review of Scientific Instruments vol 42 no 6 June 1971 F J Duarte and L W Hillman Eds Dye Laser Principles Academic New York 1990 Chapters 3 and 5 Retrieved from https en wikipedia org w index php title Ion laser amp oldid 1187096939 Argon laser, wikipedia, wiki, book, books, library,

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