The lasers they use on thick plate steel really impress me.
We have lots of $250+K laser systems at work. They are femtosecond (10 to the -15 power seconds) laser systems so extremely short pulses that are tuneable for wavelength. They will burn you or blind you but not cut steel.
When I was in grad school, a student violated all of how he was trained and ended up putting his arm in the beam and getting multiple "doughnut" burns. This was an old system that pulsed at 10 Hz. Similar to the old HS physics experiment where you measured acceleration by measuring the distance between tick marks on a piece of paper, I calculated how fast he accelerated his arm once he felt the burns. It made a nice teaching moment for my fellow students. A couple of people had burned themselves previously but those accidents were quickly forgotten. But because they remembered me measuring his arm for the calculations, we did not have any additional events like that.
Ken
