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.
That’s pretty cool! I didn’t know that they sold a sheet this large! It says that you can cut the sheet any size you want, and it still works. This would allow many test squares, 1” in size. I am considering buying this!
Charlie
I have an RF laser though, and an Arduino system controller. That allows me to modulate the beam way down reliably. Like I say, this sheet responds best on unfocused beams at what should be <1W.
I’m wondering how well this works on a large DC-excited Reci or whatever. The sheet cannot tolerate high energy. But DC-excited tubes don’t perform consistently on low duty cycles.
You could use an Arduino to make a single fixed pulse that lasts long enough to guarantee the tube ionizes and delivers output, and repeats often enough to make the impression on the mood ring sheet “live”.
However, I’m wondering if that sweet spot even exists. This plastic sheet is pretty easy to melt. It may be that a single min pulse needed to fire like a 150W Reci may be too much energy for the sheet. More likely a prob if aligning #3 mirror with the lens in place, a focused beam is much more likely to damage the sheet unless you run the Z down another 2" to widen the beam back out.