Re: Most Efficient Light Source??


"Fritz Schlunder" <me@xxxxxxxxxxx> wrote in message
news:437e842e$1_1@xxxxxxxxxxxxxxxxxxxxx

> This is most likely bogus, although at least a physical possibility. Any
> advancements to 130 lumens/watt will most likely be produced by well
> established white LED/dice manufacturers such as Cree or Nichia, not some
> single "professor" goofing around. Additionally it is unlikely a 130
> lumen/watt white LED would be based around a purple LED die since purple
> photons have more energy than blue photons, but the phosphors waste any
> excess photon energy when downconverting the short wavelength light into
> longer wavelengths.


Hmm... I just let myself fall into a trap I would like others to avoid. To
the extent of our current technology there is no such thing as a "purple"
LED that I am aware of. Purple and violet are two colors that often get
confused and mixed up. Purple isn't really a single color, it a color
produced by mixing some red and blue light. You can't exactly assign a
specific wavelength to the color purple, since it is actually a mix of
wavelengths, much like white light. Violet on the other hand is a real
single color, and violet LEDs most certainly do exist. Violet is shorter in
wavelength than blue light, so something like 400 nanometers would appear as
violet (although it might get marketed as an ultraviolet LED or near
ultraviolet LED).

Anyway, this further undermines the credibility of the article since
technically no true "purple" LED using a single LED die exists. Violet LEDs
certainly exist, and that is probably what they meant to say, but if they
really knew what they were talking about and had actually achieved what they
claim, it seems to me they wouldn't likely have made such an error. Of
course, many people simply use the words purple and violet interchangeably
when they technically shouldn't, and that in and of itself doesn't exclude
competence or achievement. Nevertheless I would consider the article with a
strong dose of skepticism.


.

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