CO2 laser tube lifespan - time used vs age of tube?

[(*steve*)]

We're changing tubes on our big laser again. We're getting about 2 years life and a bit over 1000 hours of use in that time. My research indicates we're hitting end of life due to tube age rather than beam time.

Re-reading this thread and refreshing my mind that there is He in the gas mixture makes me realise why tube age is so important.

 

[hevans1944]

AFAIK, there are only two gas lasers available for sale to the general public: CO₂ and HeNe. Both contain "laser gas" mixtures that include helium, probably for some esoteric quantum mechanical reason. Helium cannot be contained by any known substances because it is inert and can "slip past" the electrostatic bonds holding all solids together. Bottom line: helium slowly diffuses out of glass or quartz laser tubes until the tubes eventually fail to lase. One possible way (that I have not tried) to restore operation would be to place the inoperable tube inside a sealed box that can be pressurized to several atmospheres of helium gas pressure, thereby allowing helium to diffuse back into the tube. The box should be evacuated to a high vacuum before introducing the helium to ensure atmospheric contaminant gasses such as nitrogen, oxygen, argon and any other trace gasses are not also diffused into the laser tube.

To determine success (if it occurs), apply current-limiting high-voltage power, using insulated electrical feed-throughs mounted on the pressure vessel, and monitor the laser output beam (if any) throuigh a small window mounted on the end of the pressure vessel. If a zinc selenide window is used, it will work for both a 632.8 nm HeNe laser as well as a 10.6 μm CO₂ beam.

Or... replace that obsolete laser with a modern high-power diode laser. There are many wavelength options available.





i.