How to adjust beam alignment on CO2 laser machine
By Marco Wong – LightObject
One of the most challenging tasks of setting up a laser machine is the beam alignment adjustment. Without a proper beam alignment tuning, an 80watt machine may perform worse than a 40watt system. A common CO2 laser system employs three reflection mirrors and one focus lens. All optics must be fine-tuned to work properly.
1) Adjust the laser power low enough to burn a mark on a piece of paper without burning through. Align the laser tube in parallel with the XY stage frame. The easy way is to measure the distance between the tube and the extrusion bar. Even though it may not be perfectly in parallel, it should provide close enough proximity. It can be fine-tuned later after the mirror adjustment is completed.
2) Place a piece of thermal tap or sticky paper in front of the 1st mirror. Fire the laser and check the burn mark to make sure that it appear in the center. If not, adjust the laser tube until the burn mark appears in the center of the target. Then remove the sticky paper from the mirror
3) Next, move the gantry toward to the 1st mirror. Place a sticky paper on the 2nd mirror. Fire the laser and fine tube the 3 knobs on the 1st mirror mount until the beam is hitting in the center of the 2nd mirror.
4) Move the gantry away from the 1st mirror and move it toward the bottom. Fire the laser and check the burn mark on the sticker. If the second mark overlaps the first mark, then the setting is good. Tighten the adjustment knobs firmly. If the marks are not overlapped, adjust the knobs slowly on the 1st mirror until a new burn mark is overlapped on the old one. Then, lock the knobs on the 1st mirror mount firmly.
5) Next, move the gantry toward to the 1st mirror again and move the laser head to the far left as well.
6) Place a new sticker on the inlet hole on the laser head and fire the laser. Make necessary adjustments on the knobs on the 2nd mirror mount until the laser beam is hitting in the center of the inlet hole.
7) Keep the gantry location unchanged, then move the laser head toward to the far right with the sticky still attached. Fire the laser then check the burn mark to see if it overlapped. If not, adjust the knobs on the 2nd mirror mount and repeat the procedure.
8) Place a new sticky on the laser head and move the gantry away from the 1st mirror toward the bottom of the stage.
9) Move the laser head to the far left, close to the 2nd mirror.
10) Fire the laser and check the burn mark location. It should be hitting in the center of the inlet hole. If not, an adjustment is required to the 2nd mirror to correct it.
11) Keep the gantry in place and move the laser head to the far right with the sticky still attached
12) Fire the laser beam and check whether the burn mark is overlapped with the previous mark. If it is, then tighten the adjustment knobs (2nd mirror mount).
13) After completing the above procedures, a laser beam come out through the laser head tip. The beam should be very small in size and very powerful at focus distance. If the dot is not round or if the dot appears like a flash light, then the setup of the 3rd mirror is not correct and needs to be tuned again.
14) The last thing for the tuning procedure is to tune the 3rd mirror. Place a piece of paper under the laser head- the tip. Then, push up from the bottom hard enough to leave a pressure mark on the paper. It should be in a circle shape. Then, fire a laser to the paper. Remove the paper and check the laser dot location. If it is in the center of the pressure mark, then the 3rd mirror setup is good. If the burn mark is not in the center of the marking, further adjustment of the 3rd mirror mount is necessary.
*This conclude the basic procedures for the laser beam alignment on CO2 laser machine*
Happy laser cutting and engraving
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