This process could be considered frustrating - but luckily I'm finding it kind of fun. I purchased a very cheap CO2 laser. It's essentially a laser, a HPGL plotter controller and an X/Y arm to redirect and focus the laser onto the work area.

The packaging was very eco freindly with red ribbons rather than packing foam to hold everything in place during transit.

The CO2 laser looks pretty much the same design as the one developed by Kumar Patel in 1964. The active laser medium is 20% CO2, 10% Nitrogen and the rest mostly Helium. Around the outside is a water cooling jacket.

To make the laser 'lase' we excite the gas by powering up the ends of the laser tube. This excites the nitrogen molecules which bounce around. They can't lose energy by emitting photons and instead bump into the CO2 molecules. With sufficient efficiency this leads to population inversion and lots of photons.

You can't see the laser beam as it's in the infra-red. However I have a visible red laser pointer installed so I have some idea whats going on.

The machine came incorrectly callibrated. This was a challenge to fix when you can't see the main laser. I solved this by using small sheets of tissue paper and the laser on very low power to align it with the red dot laser. From there it was much easier as I could safely align the remaining mirrors just using the visible red dot laser.

HPGL Plotter

This movie shows the laser in action vector engraving. I have written some umajin script to convert a DXF file into the simplified HPGL commands the controller board accepts. The results are very good!

High Definition

You can see from the relative size of the engraving that the laser focus, controller and stepper motors do a pretty good job of handling very detailed jobs.

The next step is increasing the power so I can start cutting out my patterns not just engraving.