Thanks for that! So those devices on Amazon are just powerful diode lasers that switch on and off ten times a second - they're not even millisecond pulsed lasers.

That powerful beam looks like (dangerous) fun; I've always wanted a laser that can burn things. My inner arsonist would like to be able to set things on fire from 100m. But I'm sure the device must be illegal here.

Styropyro says you can damage your eyes just by looking at the projected laser spot. I wonder whether he's exaggerating his warning a bit.

OK, so no homemade picosecond-laser coffee for me any time soon.

The warning is *NOT* exaggerated. It is incredibly easy to damage your eyes with these tools.

I bought a cheap cat toy laser on amazon that was so powerful our eyes hurt just from testing the thing on our light gray walls etc. Some things are not worth messing around with.

Not sure what you’re being downvoted but Styropyro is correct. There’s one other aspect that people don’t talk about and that’s Q-pulsing. When you turn on 10W diode, the room gets pretty bright from the stray light. The moment you turn on Q-pulsing, the room glows uncomfortably bright, even with eye protection

Besides just diodes, there’s also the Q-pulsing aspect (hence the pico and fempto part of laser nomenclature)