Quote Originally Posted by ledtime
I used an online calculator for LED's to calculate lumens per LED. The calc says 10.471 lumens per LED. There are a 100 red LED's in the array putting it at 1,047.1 lumens. That seems pretty bad????
Well,


PLEASE NOTE that the lumen per watt figures in this document are lumens of light produced per watt of electricity delivered to the LED. Some LED manufacturers state much higher figures indicating the lumens per watt of radiated light. The latter, high figure is typically in the ballpark of 60-100 for red, 130-180 for orange-red, 220-265 for red-orange, 440-500 for yellow, 400-plus to near 660 for green (656 for Avago HLMP-C115), and around 50-90 for blue. The main purpose of this "high" figure is for conversion between radiometric and photometric units for the emitted light. If the conversion efficiency and the "high" lumen/watt figures are both known, multiply them to get the lumens out per watt in.
Beam brightness and width figures below are mostly ones claimed by manufacturers/distributors and I have NOT confirmed most of these.
Most Efficient Deep Red / Pure Red LEDs - 14-15 lumens/watt

InGaAlP LEDs with dominant wavelength at least 631 nm are sometimes called "royal red". These deep red InGaAlP LEDs often achieve 12-15 lumens/watt.

UPDATE 5/11/2009: LEDEngin makes some deep red high power LEDs, available at Mouser Electronics. These LEDs have rated peak wavelength of 655-670 nm, typically 660 nm. These appear to me to use GaAlAsP chemistry and to be unusually efficient for GaAlAsP.
The LEDEngin LZ4-00R210, LZ4-20R210 and LZ4-40R210, at 700 mA, are claimed to have typical voltage drop of 10.5 volts and typical radiant flux of 1.8 watts. This is typical efficiency of 24.5 percent.
One update of mine is that spectral analysis indicates dominant wavelength of 643-644 nm and luminous efficacy of the emitted light to be about 60 lumens/watt. If radiometric efficiency is indeed 24.5%, then overall luminous efficacy is 14-15 lumens per watt.
Other LEDEngin high power deep red LEDs achieve efficiency similar to or slightly lower than that of LZ4-00R210, LZ4-20R210 and LZ4-40R210. Red LEDs with GaAlAsP and Avago's similar AlGaAs in my experience, when doing well, tend to achieve 7-8 lumens per watt. But unlike the more efficient orangish red ones below, they are truly fairly pure red in color, with dominant wavelength (color specification roughly meaning hue) of 637-648 nm, usually 640-645 nm, and peak wavelength of 645-665 nm, usually 660 nm.

So, ya see, it's simple, but it's not that simple.

Your thoughts?

Weeze