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"Every tracer unit I looked at either used blue light or very bright flashes of white light." --1LT Caffeine
The higher the wavelength the light used to charge a phosphorescent material, the more energy imparted, the more it glows.
I used to do photographic work back in collage that used UV Light Boxes for the exposure (cyanotype prints, van dyke prints). The timers were old analogue GRALABs with the text all printed with phosphorescent paint. Usually they would glow very faintly after you switched over from the white overheads to the darkroom reds, but is you left the door open when exposing with the UV light box, the timer text would *shine*.
I bet these tracer units use broad spectrum UV LEDs to charge the BBs. That's the only thing I imagine that could charge them that fast. It makes me wonder how much luminosity you could get with narrowband UVC, the type of light used to sterilize surgical instruments. A device like that might be dangerous... though I have seen UVC wands available for de-microbing the computer keyboards of hypochondriacs. |