Importance of Regular Maintenance for High-Power Lasers

Dear Laser Users,
I am writing to discuss an essential aspect of maintaining high-power lasers, such as those manufactured by Coherent, Novanta, and Rofin, particularly lasers ranging from 250 to 500 watts. These substantial lasers have larger gas chambers that can provide enduring operation. However, the long lifespan should not be misconstrued as an indication of infrequent maintenance needs.
A common misconception that needs to be addressed is the neglect of timely regassing. It’s a mistake to completely deplete the laser gas, especially when the laser has been operating for an extended period, say 10 years. Ideally, regassing should occur around the five-year mark. This is because the laser gases tend to disassociate over time, causing a reduction in laser efficiency. When the laser power wanes, operators tend to increase the operating duty cycle, inadvertently straining the laser’s electrical system and risking damage to crucial components in the laser cavity.
As laser gas disassociates, it can lead to issues within the laser cavity, impacting the cavity plates, optics, and electrodes. The cavity plates may sputter micro-aluminum particles into the laser gas, which subsequently get embroiled in the lasing process. These microscopic particles, traveling at the speed of light, can damage the laser optics through pitting. This reduces reflectivity and, consequently, the laser’s power output. In most instances of high-power laser system failures, this sequence of events is the culprit, and the costly result is the need for optics replacement.
The good news is that regular and preventive regassing can circumvent these issues and decrease the total cost of replacements over time. Additionally, regassing can also rectify mode problems. Normally, a laser mode is Gaussian or bell-shaped. Pitted optics can alter this mode, producing divergent satellite beams. These mode changes can be easily detected using a piece of acrylic.
Overheating is another common problem caused by poor gas quality. The laser has to work harder electrically to produce the same power output, generating more heat in the process. With increased electrical consumption, cooling systems are strained, further diminishing the performance of the laser due to the disassociation of the poor-quality laser gas. By regassing, not only can we improve the efficiency of the laser but also decrease overall electrical consumption.
Should you observe any of the above-mentioned symptoms, I am here to help. Let’s have a conversation about how we can optimize your laser system for the best performance possible. I look forward to your call.
Christopher Zelich, President/CEO

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