[HN Gopher] Building a Phosphorescence Detector
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       Building a Phosphorescence Detector
        
       Author : surprisetalk
       Score  : 32 points
       Date   : 2024-11-28 01:32 UTC (21 hours ago)
        
 (HTM) web link (lcamtuf.substack.com)
 (TXT) w3m dump (lcamtuf.substack.com)
        
       | sdflhasjd wrote:
       | 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).
        
         | genewitch wrote:
         | 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.
        
       | genewitch wrote:
       | 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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       (page generated 2024-11-28 23:01 UTC)