I was looking up some laser information, stumbled across this site, and remembered that this is where I posted an insane self-experiment four years ago that I'm lucky to still have full eyesight after.
In short, I looked directly into a 980 nm laser diode that was advertised as <5 mW (although in my stupidity I never tested it). I did indeed see a deep red pinprick in the center surrounded by a cyan glow that I presume was frequency-doubled 490 nm light. I risked my eyesight a second time by putting a cheap 750 nm IR-pass camera filter in front of the laser and looking again; the deep red light was clear as it was previously, but there was no cyan glow. So I'm pretty sure I saw 980 nm near IR light and 490 nm frequency-doubled cyan light.
Luckily for me, my right eye still works fine; no vision loss. This was nowhere near certain, as everybody who replied to my thread tried to warn me to no avail. I neither regret nor recommend this amateur "experiment" but it is fun to say that I've seen 980 nm light, and that I've seen two octaves of light simultaneously. On the other hand, the 980 nm spot was totally invisible as a diffuse reflection from a white wall - only directly shining a laser into my eye enabled me to see it. I got lucky; please nobody ever do this again. But I wrote about it here:
http://laserpointerforums.com/f40/slightly-crazy-980-nm-laser-experiment-56198.html
This is the second most dangerous sciencey thing I've done. Only the time I made what I called "Hell's Mountain Dew", about six months later, eclipses it. Specifically, I went outside on a deck and, while holding my breath, added formic acid (~95%) to sulfuric acid (98%) in a glass beaker on a scale. The HCOOH rapidly decomposes to CO and H2O. I ran back inside, started breathing again, and observed the rate that the mass of the mixture fell to determine how quickly CO was being outgassed. Over a quarter of the HCOOH in an equal-volume mixture decomposes to CO within the first minute or so. I repeated this several times, until I was stopped by the scale failing because of corrosion from splattered sulfuric acid. The deck also took some damage, as did my clothing: I ruined at least three shirts and two pairs of jeans. I did at least wear safety goggles and gloves, but that and breath-holding were all the safety measures I felt like taking.
The sulfuric acid bubbles, violently at first, with carbon monoxide, which slowly subsides over the next half hour or so until it looks like Mountain Dew, if Mountain Dew were concentrated sulfuric acid rather than dilute citric and phosphoric acids and the bubbles were CO rather than CO2.
Thankfully, my backyard "experiments" did not earn me a Darwin Award. But yes, I have seen 980 nm laser light, and it is beautiful if incredibly dangerous.
