[SML] LED Blacklights

[billn at peak.org]

> At age 50, I notice that true UV light tends to look hazy to me, so I am
> guessing that my older natural lenses must fluoresce to some degree, and cloud
> my vision a little. It never did that when I was younger.

I don't think I have ever encountered a pure ultraviolet light. They have all
be arc lamps with a coating to block most of the visible light, but the
coating does not block it all.

I suppose it might be possible to make some very expensive dichroic filters to
block everything but ultraviolet.

Whether you want long wave or short wave ultraviolet depends on the
fluorescing material. Some respond to only one or the other, some respond to
both (sometimes with in different colors). I suspect every mineral has a peak
wavelength to which it responds, but an arc lamp produces a very broad band.

Bill