The influence of foreign gaseous impurities on the performance of an industrial carbon dioxide laser

Contamination in the cavities of high-power industrial CO;Experiments on an industrial 3 kW, fast-axial-flow, CW CO;The optical properties of laser internal optics after operating with cavity gas impurities were measured. Increased absorptivities in the output coupler were observed with both hydrocarbon and oxygen impurities compared to those with ultra-high-purity gases. Decreased reflectivities in turning mirrors were also measured. Deposition on the surfaces of corner mirrors were identified as carbon using energy dispersive microspectroscopy (EDAX) analysis. Mechanisms of laser output power loss with cavity gas impurities were evaluated. The major power loss mechanism is shown to be degradation of optics for both propane and ethylene. All impurities used in this investigation had negative effects on laser-cavity optical elements compared to ultra-high-purity gases. For propane and ethylene, power also decreased. The only mixture used in this investigation with acceptable long term effects had less than 10 ppm (99.999% ultra-high-purity) of all impurities.