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October 26, 2011

High-quality white light produced by four-color laser source

The human eye is as comfortable with white light generated by diode lasers as with that produced by increasingly popular light-emitting diodes (LEDs), according to tests conceived at Sandia National Laboratories.

The finding is important because LEDs — widely accepted as more efficient and hardier replacements for century-old tungsten incandescent bulb technology — lose efficiency at electrical currents above 0.5 amps. However, the efficiency of a sister technology — the diode laser — improves at higher currents, providing even more light than LEDs at higher amperages.
In the test setup, similar bowls of fruit were placed in a lightbox with a divider in the middle. In this photo, the bowl on one side was illuminated by a diode laser light and the other was lit by a standard incandescent bulb. The aesthetic quality of diode laser lighting (left bowl) compares favorably with standard incandescent lighting (right). (Photo by Randy Montoya)




A cooperative approach might use blue and red diode lasers with yellow and green LEDs. Or blue diode lasers could be used to illuminate phosphors — the technique currently used by fluorescent lights and the current generation of LED-based white light — to create desirable shades of light.

The result makes possible still further efficiencies for the multibillion dollar lighting industry. The so-called ‘‘smart beams’’ can be adjusted on site for personalized color renderings for health reasons and, because they are directional, also can provide illumination precisely where it’s wanted.

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