This is PAGE 2 of the 2000-2009 exhibit. Go here to return to PAGE 1.
2000 AND BEYOND: LEDS REACH ACROSS TEMPORAL AND SPECTRAL BOUNDARIES
These LEDs look rather ordinary, don't they?
Well, they aren't!!!
These are the world's first known zinc selenide (ZnSe) non-phosphor white LEDs that have been offered for sale anywhere. Although there was some work on ZnSe blue and non-phosphor white LEDs being done in the early- and mid-1990s, it wouldn't be until early 2004 that they would be made in quantities large enough to offer for sale. Roithner Lasertechnik has these LEDs in at least five types (5mm and 3mm epoxy through-hole, and three types of SMD; most shown in the above photograph) at the present time.
Here's a beam photograph of one of the 5mm ZnSe white LEDs.
Measures 5,800mcd on a Meterman LM631 light meter, with an If of 30mA.
This LED produces a beam with a slightly but noticeably bluish-greenish-white central area, with a "very strong dog urine yellow" (dark amber to orangish or brownish) ring outside that. This is expected behaviour with a non-phosphor, 3mm or 5mm epoxy lens LED, and does not in any way indicate a problem with this type of lamp.
Spectrally, this LED has a strong, narrow blue spike (est. peak around 480-485nm) and a strong, very broad emission in the yellow, orange, and red; with a weaker, but still significant emission in the green. The spectrum appears to be deficient in blue-green, and all wavelengths below around 470nm (deep blue and violet). My spectrometer is busted, otherwise I'd show you with a spectral analysis. Instead of that, I offer you this photograph of its spectrum:
From the datasheet, comes this snippet:
o The half-life of the optical output at 25°C is over 3,000hrs at the above If condition (20mA).
o Recommended If at 75°C is 5mA. The half-life under such condition is over 1,000hrs.
o The half-life of the lamp is inversely proportional to the square of the operating current.
They still have a small problem with short device halflives, but it's still pretty decent for a lamp.
These LEDs are apparently manufactured by Supra Optical Inc. and distributed (and possibly also manufactured) by Procomp.
I have custody of a loaner spectrometer at this time, so here's a spectrographic analysis of this LED:
Spectrometer plot of this LED.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.
This LED is an "in-between" model; between the standard 5mm LED that everybody knows, and the high powered Luxeon Star LED that some people know of, and which are used in some LED flashlights these days.
Here's a picture of one, with a standard red 5mm LED below it for a size comparison.
This particular LED produces a cyan (bluish-green) light; they are available in most typical LED colors. I don't think they make a white one yet, but I'll have to go through two boxes and a bag to be absolutely, positively, 100% certain.
I believe these "enhanced power LEDs" from Paralight (no URL available) came out sometime in 2003.
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