A question about green lasers

Hey,
The crystals/lens that I have to use to create the green light can be burned?
Do they similar to laser lens that must be coated for high power lasers so they won't butn?

Thank you!

The Nd:YAG crystal can overheat, without proper heatsinking, and be ruined, yes.

Oddly, though, really, really high power ones that crank out 40 Watts, heated AND water cooled. Apparently, the aluminum crystal matrix can tolerate more abuse, if it's preheated by a mini oven, prior to lasing.

It's not about tolerating abuse, it's about increasing efficiency through temperature tuning.