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LED Light Innovation Could Reduce Light Pollution Throughout The Globe

Apr 24, 2013 04:12 PM EDT

An innovation in LED lighting could successfully light the world’s sidewalks and roads while all but eliminating light pollution.

Published in the journal Optics Express, the researchers report that while conventional LED streetlamps leak as much as 20 percent of their light either horizontally or skyward, the new design would limit light pollution to just 2 percent.

The reason lies in the lamp’s unique, three-part lighting fixture that the study’s authors’ call “simple but effective.”

The first part contains a cluster of LEDs fitted with what’s called a Total Internal Reflection (TIR) lens, which works to focus the light so rather than intersecting, the rays are parallel to each other.

The lens-covered LEDs are then mounted inside a cavity that reflects or “recycles” the light in order to improve efficiency.

Finally, each lamp is covered in a microlens sheet that acts as a filter to cut down on unwanted glare.

Not only would such a lamp benefit anyone with a bedroom window facing bright, yellow streetlamps, but according to the New Jersey Astronomical Association, an estimated 30 percent of electricity generated for outdoor illumination is wasted on lighting areas besides those targeted.

Moreover, for years now scientists have watched migratory birds veer off course due to light pollution. Newly-hatched turtles require a dark sky in order to orient toward the ocean and have been found wandering landward or aimlessly down a beach shore on busy boardwalks. Voles and other animals have shown signs of a disrupted circadian rhythm due to artificially lengthened days.

“You talk about global change – one of the most visible changes in the last 100 years is in night lighting,” Travis Longcore, science director of the Urban Wildlands Group, said. “We’ve turned major swathes of the globe into permanent full moon, or more.”

One group called the Starlight Initiative, has gone so far, in fact, as to issue the Declaration in Defence of the Night Sky and the Right to Starlight, asserting that “an unpolluted night sky that allows the enjoyment and contemplation of the firmament should be considered an inalienable right of the humankind equivalent to all other environmental, social, and cultural rights, due to its impact on the development of all peoples and on the conservation of biodiversity.”

Longcore, who grew up in Maine, said he remembered walking outside where he could see the Northern Lights.

Of it, he said, “I could just go outside in the backyard and lie in the grass and have that universal human experience.”

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