Maintenance of CO2 laser lens
For those general output lasers, due to manufacturing process or environment pollution, almost all lenses absorb a larger part of a specific laser wavelength, and thus shorten the life of a lens. The damage to lens will affect the use or even shut down the machine.
The increase of absorption for wavelength will cause uneven heating, and refractive index changing with temperature; when laser wave length penetrates or reflex through high absorption lens, the uneven distribution of laser power will increase the temperature of lens center and lower the edge temperature. This phenomenon is called lens effect.
The thermal lensing effect caused by high absorption of lens due to pollution will arise many problems. Such as the irreversible thermal stress of lens substrate, power loss while light beam penetrates lens, partial shift of focus point position, premature damage of coating layer and many other reasons that can damage lens. For lens exposed to the air, while maintaining if not following requirement or precautions, it will cause new pollution or even scratch lens. From years of experience, we should keep in mind that: clean is the most important thing for any kind of optical lens. We should have good habit of cleaning lens carefully so as to reduce or avoid pollution cause by human, such as fingerprint or spittle. As a common sense, while operating optical system with hands, we should wear finger cover or medical gloves. During cleaning process, we should only use the specified materials, such as optical mirror paper, cotton swab or reagent grade ethanol. We may shorten the lifetime or even permanently damage lens if taking short cuts while cleaning, disassembling and installing. So we should keep lens from pollution, such as moisture protection and so on.
After confirmation of pollution, we should wash lens with aurilave till there is no any particle on the surface. Don’t blow it with your mouth. Because air from your mouth contains oil, water and other pollutants which will further pollute lens. If there is still particle on the surface after washed by aurilave, we then should use specified cotton swab dipped with laboratory grade acetone or ethanol to wash the surface. Pollution of laser lens will cause serious errors in laser output even the data acquisition system. If we can keep lens clean frequently, that will increase the lifetime of laser.
