Since it was first invented, a wide variety of lasers have been developed. Depending on the laser medium being used, it is possible to create different colours (wavelengths). These lasers include:

Gas lasers: The most important are CO2 and excimer lasers (derived from “excited dimer”: ArF, KrF, XeCl). Moreover, there are also the heliumneon and argon-ion lasers.

Liquid lasers: The medium is a dye solution, as a result of which the colour of the laser light can be varied over a wide range.

Solid-state type lasers: The most important one is the neodymium-YAG laser. The medium in this case is a synthetically produced monocrystal, yttrium-aluminium-garnet, in which some yttrium ions have been replaced by neodymium ions.

Semi-conductor/diode lasers: The latest laser types which generate light effectively from the smallest space

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