The influence of laser cavity gaseous impurities on the performance of an industrial CO2 Laser

Abstract

Contamination in the cavities of high power industrial CO2 lasers is a cause of laser performance degradation. Such degradation can result in laser downtime and significant loss of productivity. The laser cavity gas supply can contribute to this contamination, but there is confusion about the level of gas impurity concentration which can cause a degradation processes. The overall objective of this investigation was to study the effects of cavity gas contaminants on the performance of an industrial fast-axial-flow CO2 laser.A 3 kW fast-axial-flow CO2 laser operated for 2100 hours prior to this investigation was employed in a series of gas contamination experiments. The operating power was selected as 1500 W. After cleaning the laser cavity, the output power was measured using both ultra high purity laser cavity gases (99.9995%) and premixed contaminated helium (100 ppm, 1000 ppm and 5000 ppm for both O2 and C3H8). The absorptivities of output coupler were also measured after laser operation.The results show that using helium containing 1000 ppm oxygen in the laser gas mixture resulted in an increase of 1.4% in the output power (4.8% for 5000 ppm oxygen). 1000 ppm of propane resulted in a decrease of 17% in the output power. Increased absorptivities in the output coupler were observed with both oxygen and propane impurities. The negative effect of contamination (especially hydrocarbon) on high power laser performance was demonstrated.Contamination in the cavities of high power industrial CO2 lasers is a cause of laser performance degradation. Such degradation can result in laser downtime and significant loss of productivity. The laser cavity gas supply can contribute to this contamination, but there is confusion about the level of gas impurity concentration which can cause a degradation processes. The overall objective of this investigation was to study the effects of cavity gas contaminants on the performance of an industrial fast-axial-flow CO2 laser.A 3 kW fast-axial-flow CO2 laser operated for 2100 hours prior to this investigation was employed in a series of gas contamination experiments. The operating power was selected as 1500 W. After cleaning the laser cavity, the output power was measured using both ultra high purity laser cavity gases (99.9995%) and premixed contaminated helium (100 ppm, 1000 ppm and 5000 ppm for both O2 and C3H8). The absorptivities of output coupler were also measured after laser operation.The results sho...