This is the best thing ever. I started using this months ago and I am NEVER going back to burn marks.
It’s thermally sensitive “mood ring” material. It’s black when cold and turns a series of brilliant colors when warm. I can see the beam location, and its size/shape, in real time, and the colors tell a lot about beam energy distribution. You do need to be careful as it’s quite possible to melt a spot in the sheet, and at $20 for a 6"x6" that is something to avoid. I have a system controller with a test mode and RF laser so I can turn the beam down to like 0.2% and just watch it.
Best advantage is adjusting the #3 so it dead centers through the air assist cone orifice. I found the red dot less than ideal for accuracy. With this, I can drop the z down to defocus the beam so won’t melt the sheet, throw the sheet on the bed, do one adjustment and just straight-up SEE the limits where CO2 beam itself clips the cone in one direction, get it centered between the clip points, lock that screw, then do the other direction.
Since the sheet’s getting blasted with the air assist through the cone, it goes cold-black almost instantly where the beam isn’t hitting it to keep it warm. So you can clearly see the beam in real time.
The material is a bit finicky. Now that it’s cold in the building, the black is relatively stubborn. It requires more energy to burst into color and reverts back quicker, which is fine. When it was warmer, it was often a dark green and took longer to revert.