Building a Phosphorescence Detector

lcamtuf.substack.com

39 points·surprisetalk··3 comments

It would be interesting to replicate this with a shorter wavelength. I tried doing some stuff with UV LEDs but was frustrated by how inefficient they were. Bog standard 385nm "UV" LEDs emit so much blue light that weak fluorescence was easily washed out. I wonder if that could be messing with your calibration (or even if the extra blue light could be doing some sort of quenching).

the COB uv leds are much cleaner UV, in a normally lit room you can barely see the light blob where you aim them until you hit something that fluoresces. Also the lasers are pretty pure, from what i've seen personally.

But anything in the portion of UV that makes ozone doesn't get anywhere near that small - the smallest is about the same volume as a AA battery, just more squat (larger radius), and they require AC voltage, and none of the ones i got lasted very long, i imagine my AC supply didn't have enough current. they use ~18V iirc? maybe 10V, i don't remember. it's low voltage, though.

Oh this is lcamtuf, i was wondering why i liked the prose. On topic: they make uv lasers, i imagine these can be pulsed and have a fast off time. Peanut butter does glow after being hit with strong UV (like a UV flashlight with a COB UV LED in it, as opposed to these little thru-hole LEDs.)

I was curious why not use a darlington transistor right on the back of the photodiode? what's the adc say if you read the photodiode while the UV lights are on?

Well, they won't read this, probably. So i guess i'll have to rig up something similar and see for myself.

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