Look, it glows, but it's not on fire!

Green diode lasers have had quite the run. Once expensive and rare, they have now reached what is likely to be the final point in their evolution, mass produced in anonymous factories in Asia and sold for $10 with free shipping.

Mine arrived today. Of course I had to play with it. For the most part it behaved exactly as I expected it to... until I happened to hit the red power switch on a power strip, at which point the laser spot glowed yellow and illuminated the swith in red. "Aha", I said to myself, "it must have some other wavelengths in there in addition to green." So I went and got my handy diffraction grating mounted in a housing, and.... no. just three lines very near each other, all in the green. No red, no yellow.

So what was I seeing? Other red surfaces don't behave the same way. My best guess is that the neon bulb in the power switch indicator is absorbing the light and re-emitting at a longer wavelength. A second power strip behaved the same way as the first. However, the neon indicator bulb in my toaster oven did not, emitting no red light whatsoever. Perhaps there is actually something fluorescent in the plastic switch housing and not the bulb itself? I am at a loss; perhaps I shall investigate further with additional materials if I can find any others.

Update: It's the plastic. I found a fluorescent orange sticker and a couple of other things made out of red plastic which demonstrate the same effects, and some other neon bulbs which do not. The fluorescent sticker was not surprising, but I was surprised to discover these apparent fluorescent properties in the red plastic. However, they are quite real - I took the red plastic knob and held it up to my UVA tube, and it glowed a vivid orange. It appears that a fair number of common red plastics fluoresce to varying degrees. Perhaps when blue laser diodes reach the bargain-basement price range that green ones have reached, we will start to notice a new set of green things which fluoresce.



This page most recently modified on: Saturday, 08-Aug-2009 10:39:53 EDT

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