4 ms·

Look at a bright enough 980 and you will see blue, I assume as it up-converts to 490. Not sure if it was the beam exapnder or my eyes...

gresrun 8y ago
Look at a bright enough 980 and you won't see anything else!
- jakeogh 8y ago
  Very true. I find myself gently explaining laser safety way too often for comfort, even in lab environments. We don't have an intuitive understanding of the dangers. I my case, I knew the divergence and had calculated my expected wattage before taking a peek back downrange... but ya.
  - ficklepickle 8y ago
    I knew someone that briefly turned on a laser engraver with their arm in it. Not sure of the wavelength, but she claimed to feel it go through and could smell burned flesh. It was fairly new tech at the time and the doctor couldn't tell her much. She had some mild tingling afterwards, but nothing major. She didn't tell her boss because she had disabled the safety switch, for some reason that seemed good at the time.
    - jakeogh 8y ago
      Prob a CO2 laser, out at 10000nm. When discussing laser safety, the primary concern is eye damage. Burning flesh etc is bad, but that heals, and it takes way more energy. Eye damage is nearly instant, it does not heal, and lasers you can dig out of consumer electronics or buy >class 3b are hecka-capable of seriously injuring someone. Even the standard 3b lasers are no joke, and often output light outside the visible range in addition to the visible beam.
tacotime 8y ago
This is caused by a tech called Second harmonic generation, or frequency doubling. "A process in which two photons with the same frequency interact with a nonlinear material, are "combined", and generate a new photon with twice the energy of the initial photons. In some cases, almost 100% of the light energy can be converted to the second harmonic frequency. These cases typically involving intense pulsed laser beams passing through large crystals, and careful alignment to obtain phase matching. In other cases, like second harmonic imaging microscopy, only a tiny fraction of the light energy is converted to the second harmonic." https://en.m.wikipedia.org/wiki/Second-harmonic_generation https://en.m.wikipedia.org/wiki/Second-harmonic_generation

gresrun 8y ago

Look at a bright enough 980 and you won't see anything else!

jakeogh 8y ago
Very true. I find myself gently explaining laser safety way too often for comfort, even in lab environments. We don't have an intuitive understanding of the dangers. I my case, I knew the divergence and had calculated my expected wattage before taking a peek back downrange... but ya.
- ficklepickle 8y ago
  I knew someone that briefly turned on a laser engraver with their arm in it. Not sure of the wavelength, but she claimed to feel it go through and could smell burned flesh. It was fairly new tech at the time and the doctor couldn't tell her much. She had some mild tingling afterwards, but nothing major. She didn't tell her boss because she had disabled the safety switch, for some reason that seemed good at the time.
  - jakeogh 8y ago
    Prob a CO2 laser, out at 10000nm. When discussing laser safety, the primary concern is eye damage. Burning flesh etc is bad, but that heals, and it takes way more energy. Eye damage is nearly instant, it does not heal, and lasers you can dig out of consumer electronics or buy >class 3b are hecka-capable of seriously injuring someone. Even the standard 3b lasers are no joke, and often output light outside the visible range in addition to the visible beam.

tacotime 8y ago

This is caused by a tech called Second harmonic generation, or frequency doubling. "A process in which two photons with the same frequency interact with a nonlinear material, are "combined", and generate a new photon with twice the energy of the initial photons. In some cases, almost 100% of the light energy can be converted to the second harmonic frequency. These cases typically involving intense pulsed laser beams passing through large crystals, and careful alignment to obtain phase matching. In other cases, like second harmonic imaging microscopy, only a tiny fraction of the light energy is converted to the second harmonic." https://en.m.wikipedia.org/wiki/Second-harmonic_generation https://en.m.wikipedia.org/wiki/Second-harmonic_generation