[sdiy] Re: Other LED's

[Jim Addie]

Have you actually seen one?  I lit mine up yesterday.  First, while 
the brightness is unimpressive, there is no compelling reason to 
stare directly into it for hours.  It just doesn't look that 
exciting.  And given the wavelength, it would take quite a stare to 
do any damage, if damage were even possible at all.  You can stare 
directly into a blacklight tube for hours, nothing happens.  There 
isn't even a warning about potential damage.  Blacklight tubes are 
closer to the dangerous spectrum than a UV LED (320 to 340 for the 
blacklight).  There is also much more power in a tube (oh please, 
let's not get into the focus issue).

I think the warning on the LED data sheet was put there by some legal 
department guy just trying to cover the company's hind end.  The 
reality is, no problem.

But hey, if you don't need the UV, just get a blue one.  They look 
better anyway.

>Agreed to what you say, but the point is that you don't notice the UV LEDs
>being as bright as they are.
>They look like friendly lads to the eye, while in reality your may stare
>into a very bright light source.
>
>Theo
>
>
>----- Original Message -----
>From: Jim Addie <j.addie at mindspring.com>
>To: <synth-diy at dropmix.xs4all.nl>
>Sent: Wednesday, March 24, 2004 6:03 PM
>Subject: Re: [sdiy] Re: Other LED's
>
>
>>  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?"
>>