Gas laser
A gas laser is a laser in which an electric current is discharged through a gas to produce coherent light. The gas laser was the first continuous-light laser and the first laser to operate on the principle of converting electrical energy to a laser light output. The first gas laser, the Helium–neon laser (HeNe), was co-invented by Iranian-American physicist Ali Javan and American physicist William R. Bennett, Jr. in 1960. It produced a coherent light beam in the infrared region of the spectrum at 1.15 micrometres.
Gas lasers using many gases have been built and used for many purposes.
Carbon dioxide lasers, or CO2 lasers can emit hundreds of kilowatts at 9.6 µm and 10.6 µm, and are often used in industry for cutting and welding. The efficiency of a CO2 laser is over 10%.
Carbon monoxide or "CO" lasers have the potential for very large outputs, but the use of this type of laser is limited by the toxicity of carbon monoxide gas. Human operators must be protected from this deadly gas. Furthermore, it is extremely corrosive to many materials including seals, gaskets, etc.
Helium–neon (HeNe) lasers can be made to oscillate at over 160 different wavelengths by adjusting the cavity Q to peak at the desired wavelength. This can be done by adjusting the spectral response of the mirrors or by using a dispersive element (Littrow prism) in the cavity. Units operating at 633 nm are very common in schools and laboratories because of their low cost and near perfect beam qualities.
Nitrogen lasers operate in the ultraviolet range, typically 337.1 nm, using molecular nitrogen as its gain medium, pumped by an electrical discharge.
TEA lasers are energized by a high voltage electrical discharge in a gas mixture generally at or above atmospheric pressure. The acronym "TEA" stands for Transversely Excited Atmospheric.
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