[sdiy] Re: Other LED's

[Jim Addie]

This data sheet shows the peak wavelenght at 380nm, which is WELL 
into the "long" UV range...the UVA band, which is 400nm to 315nm. Get 
enough UVA and you'll get a suntan.  But you have to get a LOT for 
quite a while - check the intensity of light at your local tanning 
salon beds. UVB (315-280nm),on the other hand, can cause tissue 
damage, and eyes are at risk.  UVC (280-200nm) is even more 
dangerous, and is filtered out of sunlight by the atmosphere, and is 
damaging to all forms of life.  A 240nm UV source can be used in 
minerology to make certain rocks and minerals glow.  The very common 
Black Light tubes you can buy at any hardware store centers at 320nm, 
and will make your white shirt light up bright blue, but rocks and 
minerals just sit there dark.

I don't think there's any real concern about the dangers of UV LEDs 
here.  Just don't sit and stare into the LED with it 2 inches from 
your eyeball for hours on end, you'll be fine.  But you wouldn't do 
that with a 4000mcd LED of any color, now would you?

Oh, by the way, a super bright IR LED will do eye damage too if 
stared into at length.



>   Again, be very careful with these.  Notice the warning on the datasheet:
>
>http://rocky.digikey.com/WebLib/Lumex/Web%20Data/SSL-LX5093SUVC.pdf
>
>   "Caution: emits ultraviolet radiation.  Protect your eyes and skin
>during operation as UV radiation may be harmful to your health."
>
>   These things are giving OSHA guys nightmares.  I really can't recommend
>using them as user interface display devices or in any device where the
>LED is directly visible.

Luckily, I haven't used it much, back to yellow LEDs I guess.

So my next question is, "if these things aren't recommended for user 
interface, what are they recommended for?"