What if we apply a phosphor filter on the flashlight to make it glowing white? And make it easily switchable/slide to control visible light.
Look here https://youtu.be/Axvkl4deMAQ?t=126
Where can I take a 20mm filter?
The guy just bugged me how he was repeatedly using blue and UV interchangeably.
Wellp, you can get one of those pieces from the bulbs and cut it into a circle (dome, actually).
And you don’t need a UV LED unless you want UV. Blue would suffice. Lotta things fluoresce under plain blue light.