The following outlines the proper procedure for cleaning optics that has been removed from the laser system. To prevent the inadvertent misalignment of the laser system optics should be installed cleaned in their mounts whenever possible.
Optic cleaning is not a required component of a regular laser system maintenance schedule. Optics should only be cleaned as a corrective action for marked power decrease or poor mode quality. Optics should not be cleaned unless signs of contamination are clearly visible on the optic surfaces. Unnecessary cleaning will only shorten the life span of the optical coating.
Optics and optic coatings can be easily chipped or scratched. Therefore, to prevent damage when removing or replacing mirrors, always grasp the optic by the outer edge. Never touch the optical surfaces with bare skin.
Handle laser optics with care. A scratch, trace of dirt, or film will diminish the laser’s efficiency. Always use finger cots, latex gloves, or the equivalent when handling optics, and use a clean, cushioned work surface.
- Remove optic from holder and place the optic on its edge on a clean piece of lens tissue. Do not allow the optic to rest on one of its polished surfaces. Allow enough time for the optic to cool down to room temperature.
- Once the optic has cooled, examine the optic at different light angles for signs of contamination or scratches. If required, clean the optic using the cleaning procedure outlined below. If any scratches or contamination cannot be removed, the optic must be replaced.
- If no scratches are visible, breathe on the optic. The surface should fog with no discoloration. If any discoloration appears the coating has been damaged and the optic must be replaced.
The Drop and Drag Method
- If applicable, place the laser system in Current control mode of operation. For Ion laser systems disengage PowerTrack if this option is available. Record the laser system output power, and output mode characteristics if applicable. Turn off the laser system, or block the pump laser beam if the optic to be cleaned is in an oscillator or amplifier.
- Place a drop of Methanol in the center of a lens tissue. Place the wet portion of the lens tissue on the optic surface and slowly drag it across the optic. The lens tissue and optic should be nearly dry before completing the drag. Note that the optic may need to be held in place during this process.
- Inspect the surface of the optic as outlined above. If streaks or contamination can be seen repeat the cleaning process using a fresh lens tissue.
- Re-install the optic, being careful not to scratch the surface. Note that a small arrow (>) is drawn on the side of all Coherent optics. When the optic is properly installed, this arrow will point into the laser cavity.
- Turn on the laser system, or unblock the pump laser beam. Using only the mount tilt controls of the optic that was cleaned, optimize the performance of the laser system. Do not clean another optic until the system performance meets or exceeds that previously recorded.