A gas laser is created by a process in which an electric current of varying power is applied to a body of gas held in a sealed cavity to produce a coherent source of light. The gas laser was the first laser to be made of continuous light and also was the first laser to operate by converting electrical energy to a light output. Gas lasers have several advantages over other forms of lasers; the gain medium used to stimulate the power of the beam can be made using a relatively cheap and attainable helium-and-neon combination, as was used in the first gas laser. On top of this, the gas is nonvolatile, so damaging the gain medium is not a significant concern.
The first gas laser was made using the combination of helium and neon gases to pass the current through and was subsequently dubbed a helium-neon laser. It was invented by in 1960 and further developed by Bell Telephone Laboratories in 1962. The gain medium used in the laser produced a coherent beam of light in the infrared region of the spectrum, creating the archetypal red laser beam. This gas laser was, up until the invention of affordable diode lasers, used in bar-code scanners. Since then, the laser has been used in educational and optical research laboratories because of its relatively small power output and low cost.
A carbon dioxide gas laser, being capable of emitting hundreds of kilowatts of power, is the most powerful continuous-wave lasers that were available as of 2010. Carbon dioxide gas lasers also are quite efficient, with an output-to-pump power ratio of potentially 20 percent. At the higher outputs, this gas laser is used in industry and manufacturing as a cutting and welding tool. The beam also can be modified to provide a less-intensive beam that, when coupled with a conducive atmosphere, is used to provide rangefinder sights for long-range weaponry.
An ion gas laser is a laser made with an ionized gas, such as argon or krypton. These lasers require a large amount of current to excite the ionic transitions necessary to create a focused beam, so they are some of the least efficient and least powerful lasers. Ion lasers, because of the amount of current they require, need to be water-cooled in order to dissipate the intense heat produced by the production of the beam. The uses for this particular gas laser are mostly medical and scientific, but they also are used to create white light beams for laser light shows.