John Shutt wrote:
I sort of "led" (no pun intended) you astray when I said UV
photons are emitted from "white" LEDs. What I should have said
was just "photons."
It wasn't you, John. It was the article I posted, when it said
"near-ultraviolet."
-----------------------
LEDs shine as replacement for lightbulb
R. Colin Johnson
(11/16/2007 12:28 PM EST)
URL: http://www.eetimes.com/showArticle.jhtml?articleID=203101640
[ ... ]
Now, Professor Elisabeth Holder and her colleagues at the University of
Wuppertal (Germany) have collaborated with professor Hilmi Volkan Demir
of Bilkent University, in Ankara (Turkey), on a new approach to crafting
white LEDs that they claim yields a very high color-rendering index,
making them suitable for professional users from graphic artists to
horticulturists.
The key to the new technique is to embed various types of inorganic
luminescent nanoparticles into a highly fluorescent organic polymer
base, then pumping the mixture with a near-ultraviolet LED. The result,
according to the researchers, is hybrid organic/inorganic LEDs that
produce white light that contains almost every wavelength in the
spectrum, and, thus, can render most any color accurately.
------------------------
However, I looked again at the Dutch paper I posted:
http://www.einlightred.tue.nl/lightsources/history/light_history.pdf
and it says that the wavelength of domestic fluorescent lights is
"ultraviolet light at 253.7nm and 184.9 nm." At least, in their original
form.
This compared with "wavelengths between 450 nm and 470 nm blue GaN" as
stated in the Wikipedia article. So indeed, that's significant.
I trust you're right, that photos won't fade. Now let's get some LEDs
bulb replacements out there.
SPEAKING of which, we just saw last night that Philips has LED Christmas
lights out on the market. Too bad they cost just over three times as
much as the regular ones.
Bert
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