I had a 200mw red laser die recently. It was working fine at first. Then I noticed it was only putting out about 1mw. The only thing I was doing with it in between was measuring the beam height so I could make a spacer. I was measuring height by shining the beam onto the head of screw. The screw was stainless steel and shiny. I think the laser probably shined back into itself. So, would that kill it? If so, how careful do you have to be? Would shining onto a piece of white paper reflect enough to be a problem? Or does it have to be mirror-like? I think I learned my lesson. But I want to make sure it doesn't happen again so I'd like to know the facts.