A gas laser needs laser gases in order to be able to generate laser light. The gas mixture for a carbon dioxide laser contains 60-85% helium, 13-55% nitrogen and 1-9% carbon dioxide. The exact composition varies depending on laser type and manufacturer. Certain types of lasers also require small additions of other gases e.g. oxygen, hydrogen, xenon and carbon monoxide. Toxic gas components require extra safety measures as concerns the gas supply system.
Gas mixtures for excimer lasers often consist of 0.05-0.3% halogens (fluorine or hydrogen chloride), 1-10% noble gases (krypton, xenon or argon) and 90-% buffer gases (helium or neon). For safety reasons, halogens must always be diluted with helium or neon.
Laser gas purity
A modern carbon dioxide laser requires laser gases of high purity. The occurrence of impurities in the laser gases reduces the laser’s capacity, for example, by lowering the output and disturbing electric discharge while increasing wear and tear on the laser optics. The most damaging impurities in this context are water vapor and hydrocarbons.
As a rule, impurities in the laser gases do not come from the gas cylinders; it is much more common for them to be introduced via incorrectly structured gas supply systems. Therefore, a prerequisite for reliable and satisfactory laser function is that the choice of components and installation is undertaken by specialists.
Supply of laser gases
Laser gases for carbon dioxide lasers are supplied in separate gas cylinders and are mixed in the laser via a mixer, or as ready-mixed gases.