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CO2 Laser Tubes
Frequently Asked Questions
CO2 laser tube is the active medium and one of the primary components of CO2 lasers. As the name describes, a CO2 laser tube is a long tube, often >1m long, that is filled with a mixture of carbon dioxide, nitrogen, hydrogen and helium. It is the medium where the laser radiation is generated and amplified.
As the primary component of CO2 gas lasers, CO2 laser tubes need to maintain a certain set of specifications to be able to output a high quality laser radiation. As the laser operates, these tubes age naturally. The primary reason for aging is the change in composition of the gas mixture that we discussed in our “Did You Know” section. For optimum laser performance it is important to maintain the correct ratio of concentration in the mixture of gases. As the CO2 laser ages the carbon dioxide inside the tube decomposes into carbon monoxide (CO) and oxygen. The rate of this breakdown is correlated with the intracavity powers and can be faster when operating the tube near its max rated output power. Over time the laser tube may also become de-pressurized which could result in laser power degradation prematurely. Finally contamination of either end mirror or output coupler can both deteriorate the output power and the beam quality. When the laser output power falls outside of the specified range it is worth looking into the laser tube as one possible culprit.
CO2 Laser tubes come either in all glass, all metal or hybrid glass-metal construction. Glass CO2 laser tubes are the most offered variety in the market given their affordability. Glass tubes require direct current pumping which is also a cheaper alternative to RF driven pump architectures present with metal CO2 laser tubes. Despite these obvious advantages, glass laser tubes have some drawbacks including micro fracking and fracturing over time as well as the need for better thermal stabilization which often requires active water cooling. As a rule of thumb metal tubes also offer better beam quality and operating stability compared with the glass tube alternatives. Metal tubes required RF drives as the pump source and overall are based on a relatively more expensive architecture.
CO2 Laser tube technology is quite mature at this stage and many CO2 laser tubes come with multi-year warranty offering operating lifetime anywhere from 2,000 Hrs to upwards of 10,000 Hrs. if in doubt, always consult the operating manual and ensure warranty information before making a purchase.
Yes, it is possible to have your CO2 laser tube refurbished. There are service providers in the market that offer such services. This could be a viable option if the replacement laser tube is either very expensive or hard to find. You can start by inquiring from the laser manufacturer, which might be able to provide some guidance.
CO2 laser tubes are sealed and require minimal maintenance over time. While operating a laser machine you should ensure that dust, debris and any contamination stays out of the vicinity of delicate intra-cavity optics including the end mirror and output coupler. Make sure you keep clean environment. From time to time it may require cleaning the end mirror and the output coupler, which can be done by a qualified professional. You should also ensure that the machine always operates within the specified temperature range and if it is equipped with a chiller it maintains the required temperature. If you are observing deterioration in the output it is best to contact a specialist to perform necessary diagnostic procedures especially if the machine is still under warranty.
CO2 laser operates in the far IR region with a typical output of 10.6um. They can operate in both CW and pulsed modes. Most laser engraving machines operate in pulsed model. In terms of average powers, the CO2 laser tubes can produce anywhere from a few mWs to as high as a few kWs of power for high end laser material processing machines.
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