CO2 laser gases usually contain the mixture of helium, nitrogen and carbon dioxide. For some lasers the gas mixture shall also contain small amount of CO, H2 or He. The composition of the laser gas mixture depends on its type, capacity and manufacturer. The laser gases are usually supplied in separate cylinders or preliminary mixed and supplied in one cylinder.
The admixtures in the laser gas mixtures can impede the operation of CO2 laser due to lowering its power output, disturbing the electrical discharge homogeneity or gas consumption increase. Besides the admixtures affect the internal optic elements, for example the condensate on the cooled optic elements, which changes their reflecting capacity. As a result the most part of the lasing will be absorbed by optics, which will result in its damage. Fortunately, this process commences very slowly and it can be compensates to some extend by adjustment of the equipment settings prior to the system failure. This can lead to such unpleasant consequence as expensive repair, though the unplanned shutdowns and operations interruption can also cause many problems.
As a result when analyzing the laser gases it is necessary to review not only their overall purity but also the type and amount of the admixtures, which may remain in the cylinders. For several years it has been known, that water vapors and hydrocarbons are the most harmful admixtures for high-power lasers and it is necessary to minimize the water vapors and hydrocarbons in the laser gases.
However, quite pure gases in the cylinders can be contaminated on their way to the laser, if the gas feed system does not comply with the requirements. Just imagine how the usage of the hoses made of the unsuitable material can influence high-purity gases!