Nd:YAG lasers always creep me out. I worked in a lab that had an Nd:YAG with two janky doublers: 1064 -> 532 -> 266 nm. The output energy was supposed to be a few mJ (IIRC), but it was basically zero. So the students operating it took off the second doubler and fired it at a bookend. Nothing (well, nothing visible). Took off the first doubler. After investigation, the zapping sound was the paint vaporizing off a computer at the other end of the lab, because the beam was actually scooting just past the bookend. 1064 nm is almost the worst wavelength you can work with. (Okay, 233nm is probably worse, but the available energy with a setup like this is much lower.)
I have a green laser pointer, and I made a point of buying a diode laser. It’s a slightly different color than 532, its battery life is better, but, critically, there is no way it could malfunction or be sloppily constructed to leak infrared light.
I just searched Amazon. There are plenty of green “diode” lasers, 532nm, ~100mW, for very little money. I don’t believe that for a second — those are surely crappy frequency doubled Nd:YAG lasers, probably unfiltered (that filter wouldn’t be cheap, and it might fail anyway under that ridiculous power level), and they will blind you when some funny reflection of the, I dunno, 500mW of stray IR light hits your eye.
Now that real name brand laser pointers are mostly gone, if you actually want green, get a 515nm laser or something along those lines. Stay away from 532nm!
I have a friend with multiple green and red lasers, some from aliexpress.
Years ago when the hype wasnt really there he visited me and wanted to show off. I have 3 dogs and I really like this kind of tech but I forbid it to turn that thing on near me, especially in my flat. Even if they are directed away, the chance of unpredictable reflections is just too high for a bit of fun.
Excellent question. You frequency-double 532nm and make a typo. I meant 266nm.
There are crystals that have nonlinear responses to high electric fields, and if you hit them with enough laser light, some of it comes out at half the wavelength. A lot of it also comes out at the original wavelength. Most 532nm lasers work like this, but other input wavelengths are possible, like starting at 532, doubling again, and getting 266nm.
This was a long time ago, and it wasn’t my project, so it’s possible it was slightly different, but I definitely remember the 532nm stage. And 266nm sounds credible for what the group was trying to do with the laser.
There are some recent papers on doing it, and they even seem to have gotten decent efficiency.
The lab I was in was doing this in 2000, and I suspect they got their frequency doubler from some other lab. It worked, but it certainly didn’t work well. The 1064nm laser was decently large (a couple J per pulse, from vague memory), and the expected UV energy was quite low. The laser was being used for some form of imaging at short range (fluorescence or absorption in burning gasses? Maybe Raman spectroscopy if everything got lucky?).
Nd:YAG lasers always creep me out. I worked in a lab that had an Nd:YAG with two janky doublers: 1064 -> 532 -> 266 nm. The output energy was supposed to be a few mJ (IIRC), but it was basically zero. So the students operating it took off the second doubler and fired it at a bookend. Nothing (well, nothing visible). Took off the first doubler. After investigation, the zapping sound was the paint vaporizing off a computer at the other end of the lab, because the beam was actually scooting just past the bookend. 1064 nm is almost the worst wavelength you can work with. (Okay, 233nm is probably worse, but the available energy with a setup like this is much lower.)
I have a green laser pointer, and I made a point of buying a diode laser. It’s a slightly different color than 532, its battery life is better, but, critically, there is no way it could malfunction or be sloppily constructed to leak infrared light.