P3D Re: Viewers and white LEDs WARNING

[Tom Hubin <thubin@xxxxxxxxx>]

Lme Kbee wrote:
> 
> DO NOT USE WHITE LED's IN A VIWER!
> 
> I looked into this, and was told at a realy great
> electronics store that the way they are able to get
> the white lite uses(something I can't remember the
> name of), and that (what ever the stuff was called)
> can cause blindness.  He said that if you aluminate
> something with the lite it should be ok, but directly
> into the eye will be dangerous.
> 
> SO, PLEASE DO NOT USE WHITE LED's IN A VIEWER.

Hello Lincoln,

I appreciate your concern but you need to be more specific. Vague
hystrionics don't count. Radio Shack type sales clerks do not qualify as
experts in much of anything. So please cite valid references and I will
be happy to read and interpret.
   
Some white LEDs are very bright. That is the point. That is why they are
good light sources. Any of the Halogen lamps used for viewers will
appear just as bright if you look directly into them. Just like looking
into the sun. If you feel that an LED is too bright you can dim it by
reducing the current to the LED. Unlike reducing power to filament
lamps, this will not change the spectrum or color temperature.

Of course, you never should look directly into any laser or laser diode.
Especially not one that is IR or UV because you cannot sense the light
even while it is doing damage to the cornea or retina. But an LED is NOT
a laser diode. And white light LEDs ARE visible.  

Tom Hubin
thubin@xxxxxxxxx