Beam combiner alignment

Nov 4th 2021

To make use of the red dot beam combiner, we need to align it with the CO2 laser first.

Stick a piece of paper about 1inch away after the beam combiner. Use low laser power so the paper does not get burned. Pulse the CO2 laser to mark on the paper. Align the red dot to match this first mark. Move the laser head to the furthest corner of the working area. Stick the paper to the 3rd mirror window on laser head. Pulse CO2 laser to mark on the paper. Adjust the red dot to match this second mark. If now the red dot does not match the first mark, the red dot beam combiner housing needs to be moved. Then repeat the above process.

The red dot does not have to coincide with the CO2 laser to help CO2 alignment; the red beam only needs to be in parallel with the CO2 beam. For example, when the CO2 dot is adjusted upwards by 2mm, the red dot also moves up 2mm. Sometimes the red dot is too bright; we cannot see the CO2 burn mark well if they are coincided.

Relative position between the red dot and CO2 mark does not change, which is still useful for CO2 alignment: