I know to do real 3d engraving you need an RF tube laser, but I was just curious what the physical limitation was on varying the pulse power on a glass tube laser. I tried to Google it and couldn't find anything substantive. I've always heard it's that the tube can't stabilize to the new power level quickly enough, is that correct?

I'm wondering from a purely academic standpoint. The Glowforge does multiple power level engraving. I'm assuming it's because they engrave at glacial paces, meaning they have oodles of time to switch the tube's power level. They claim it's a magic power supply that they custom designed, but I don't buy it. I'd love to learn something new though about physical limitations to changing the power level on the fly like the RF tubes do.

And also I realize dithering gets you most of the way there for nearly all real world applications, but hey I'm an engineer and am curious about the underlying physics