Is the strength of blacklight Flourescence proportionate to the strength of the source, or is there a threshold?

Say I have a black light hooked up to a dimmer switch and a material that fluoresces under black light. As I gradually increase the 'brightness' of the black light, can I expect the fluorescent material to fluoresce gradually brighter, or is there a definite 'threshold' below which there is no fluorescence?

Will the same hold true for IR-fluorescent materials and IR sources?

Thanks in advance!

orksecurity7 years ago
Going the other direction (increasing the excitation) does hit a limit eventually, when you've run out of valance electrons to pump to the excited state. And I would presume there's an asymptotic approach to that limit.

Odds of your ever hitting the limit with normal UV sources are pretty darned low, though.
lemonie7 years ago
UV tubes work on plasma-discharge, like CFL and other fluorescent tubes. They don't take well to dimmer circuits because you need so much power to ignite the plasma, and they're current-controlled.

Otherwise you're correct in your expectations. You might think about controlling the amount UV light with an aperture, e.g. a slit which you can adjust the width of?

Well, there's a threshold for where your vision won't pick up any fluorescence but it happens regardless, until there's no light of that wavelength hitting the material...

I would give you a rundown of the principles behind it but I can't remember the way to describe it very well.

The easiest way to experiment is with a blacklight and some fluorescent materials, move them further away and get and idea, if you've got a camera with a reasonably sensitive sensor you can observe it beyond your vision, though it might involve some slow shutter speeds to really test it.

I have two blacklights somewhere in the house if you're really interested though I don't like them very much, my eyes glow and it makes for a headache inducing haze... Sadly they don't fluoresce in a creepy evil way...