Heh heh, lasers are cool
2000 Trillion Watts is a considerable amount of energy. Given 2000 Joules, this equals the amount of energy released by Rk-95 assault rifle bullet (7.62 x 39 mm), or AK-47 if you didn't serve in Finland. So absorbing this energy completely to a human body could potentially be lethal. And that's cool, normally lasers just burn you!
Makes me wonder what kind of interesting things can the instant electric field amplitude do within matter....
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Have had my share of lasers too. Normal laser scanners are typically eye-safe (laser class I) as long as they are scanning, i.e. the beam must move. If the scanning stops and the laser fires, the scanners would probably go to class III, and are NOT eye safe. Make no mistake, manufacturers go to extreme lengths to guarantee that the laser does not fire if the beam is not moving! Other possibility is to expand the beam diameter so much that the laser is anyways Class I as they eye cannot possibly gather as much energy, but this tends to increase the size of the things and is not applicable everywhere.
You've probably heard that human eye can see wavelengths up to ~ 700 nm. That was not the case for me, I could see up to around 800 nm of Fraunhofer lines in a dark laboratory. I actually suppose most people would be able to do that, but only if the eye is accomodated, and this does not happen in normal illumination. Well, to cut to the chase, I've actually also seen 785 nm wavelengths in normal room illumination. That was with a 150 mW laser that was used in a Raman system. The system was shining that energy to a spot on a paper, and I observed the paper with a naked eye. First year at work, I know. I actually could see the spot, just faintly. I later on realized how big a risk and dangerous this was, and has then participated more on the laser safety briefing of the new guys... The scattering from the paper is probably what saved my eyes in this case.
We had a class IV laser shining through a system some years ago. As stupid as it is, the laser safety goggles occasionally dampen the energy far too much, so that you cannot see the spot at all. In that case, we discovered that the only way to adjust the direction of the spot was to remove the goggles. It is one of those moments where you really ponder how much of Physics you do know in real life, as it is now really personal. Turned out that I was right, the spot was so large (20 cm x 20 cm) that when the 500 mW of power was spread over it (target was black and scattering), the brightness was well within Class I limits. But I do recall thinking that if I absolutely have to do this, I'll open my weaker eye first, even if I know that this should be safe.
Raman systems are also prone to massive amounts of CW power. We had a Class IVb (800 mW) laser in the lab, which was used to detect certain compounds. The problem is, that 800 mW went to somewhere, and it turned out we were actually measuring smoke coming from the plastic walls of the device. But at least we got a good signal!
The last one I can share was not a laser system, but a solar simulator. My colleagues wanted to test solar cells, and Mika went away and did one simulator. It used a 300 W Cermax bulb (electrical power), that could convert about 50 % of that to radiometric energy, and 3 % of that within the visual region, the rest being spread to IR (the reason such source is used in the evenness of the spectrum, it's hard to equal that). In order to check if the beam was properly focused in a bottleneck area where the beam was supposed to enter a 1 cm x 1 cm area, I just used a piece of A4 covering the bottle neck with it. The mistake became immediately obvious when the power was turned on and the paper evaporated there, leaving a hole of size 1 cm x 1 cm with coaly edges in the paper. Yes, that 150 W of radiometric power was just focused on that 1 cm x 1 cm area, leading to an average irradiance of 1.5 MW / m^2, or equivalent of ~1500 suns (1 sun ~ 1000 W/m^2).
The pilots have a saying that in the beginning, you have all luck an no experience, and the idea is to convert luck to experience before luck runs out. Occasionally, I feel the same with lasers.
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