P3D White LEDs hazardous?

[Tom Deering <tmd@xxxxxxxxxxx>]

>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.

I have done a bit of research into this, and I can't see why a white 
LED would be any more dangerous than any other light.  Just the 
opposite, in some ways they would be excellent, it they weren't so 
incredibly expensive.

White LEDs work two different ways.  One kind is actually two 
separate LEDs in one package.  The two colors mix to come close to 
white.  The other kind is actually a blue LED, but it is made of a 
special material that glows with an opposite color when illuminated 
by the blue light.

Either way, it's just light.  There is no radiation, unless you count 
the light itself, which of course is a kind of radiation. Not a 
source of infrared or ultraviolet, either. I suspect the salesman 
mentioned above was confused.

Actually, in a way, white LEDs seem like the perfect slide 
illumination source, since they are ten times more efficient.  Think 
of getting ten times the life from your viewer batteries.

A couple big problems, though.  One, they are incredibly *expensive*. 
White LEDs are fifty times more expensive than regular LEDs.  You 
could buy batteries for a regular viewer for years and still come out 
cheaper.

Two, they aren't really white, just pretty close.  You've got to have 
other LEDs to balance the color, and it's tricky.  Together with the 
rest of the circuit, that drives the cost up further.

But they should be as safe as any other light source of the same intensity.

Cheers,

Tom
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