I’m thinking about replacing our old and scratched safety window:
As far as I can tell, transparent acrylics should work. After all it absorbs CO2 laser radiation, or else it couldn’t be cut. Tinted would be nice, because the spot being lasered can be super bright.
Glass should also work, but then I cannot easily cut it in shape myself to make it fit.
Any suggestions? What material do companies like Trotec use?
A piece of acrylic would be fine. Tinted is nice because it cuts down on the glare. But clear will work as well.
You could also try to polish the old window with fine auto polish.
Lots of resources applied to polishing acrylic are about “polishing headlights” but apply to any acrylic really. 
Thanks for the suggestions! I think I can afford a piece of brand new tinted acrylic. If the acrylic is strongly tinted, it may make sense to upgrade the internal light as well, to make it much brighter.
My understanding is it should be poly carbon (lexan)
Not poly acrylic (plexiglass)
If the laser beam gets reflected to the shield, it could burn through poly acrylic.
I’m far from an expert but thats my understanding.
According to the Eurolaser article laser cutting of polycarbonate a
CO₂ laser does cut polycarbonate. So I don’t see the fundamental
difference, unless it takes a considerably longer amount of time.
I also wonder in which scenario the laser beam would be deflected
towards the hood anyhow. Maybe if a mirror gets loose. Most materials
are not reflective to the 9–12 μm wavelength of the CO₂ laser.
The window needs to be made of something that can be cut, because it needs to absorb light at the laser frequency, which is how a laser cuts. It’s just that you hope that specular reflections etc. are sufficiently diffuse that they don’t heat the window to the point of cutting, which you really shouldn’t be putting yourself in danger of doing by very poor selection of materials to cut…
Right. Some materials are harder to cut, though. Glass would be an option, but it will crack when exposed to the beam for a longer period of time. A few years back, I tried cutting a circle into a mirror using a Trotec Speedy 400:
The hole for the pendant is drilled. While there are CO₂ laser cutters for glass, I recall they only work for very thin material, for example glass covers for displays.
The material currently in the hood of our K40 type laser cutter does not feel like acrylic on touch. It may be PC or PS, possibly due to cost.
Well thats news to me. Every aticle I’ve read and maker space I’ve been to says no. Polycarbonate just bubbles and burns and leaves a brown gooey mess.
Ive never tried it but i would love to be able to laser polycarb. Acrylic is so brittle and breakable.
Have you lasered poycarb?
I haven’t. Note that the Eurolaser examples are of PC foils, which are thin. Maybe that’s why it works. Try cutting foil with a short lens. Then you get a lot of energy in a tiny spot.
