By Patricia Daukantas

When New York’s Rockefeller Center Christmas tree burst into glorious colors on national television last night, the brilliant light came from energy-saving LEDs for the first time ever.

Until this year, incandescent bulbs had always lit the giant tree, which has been a Big Apple tradition since the 1930s. However, the 2007 tree, an 84-foot (25.6-m) Norway spruce, is strung with 30,000 LEDs on 5 miles (8 km) of electrical wire. For each of the 42 days that the tree is illuminated, it will consume 1,297 kWh of electricity instead of the 3,510 kWh used by the old-fashioned bulbs. The difference is enough to power a 2,000-square-foot (186-m²) single-family home for a month.

According to New York municipal officials and the Rockefeller Center management, the “green” tree is part of an environmentally oriented package that includes installation of a 363-panel photovoltaic roof that feeds into the electrical grid of the building complex. The roof will power the tree during the holiday season, and when the tree is taken down in January, the wood will be cut up for use in Habitat for Humanity homes.

With energy prices at record highs, more manufacturers are starting to produce LED holiday lighting for home use, too. Not only do LEDs save caboodles of electricity, but they last up to 100 times longer than conventional bulbs. If you’ve ever spent a December afternoon wrestling with a long string of series-linked incandescent lights, trying to figure out which bulb blew out and made the whole string go dark, you’ll appreciate the long lifetime.

Nevertheless, LED lights still cost more than their old-fashioned counterparts, so it may take a family a few seasons to recoup the cost.

For photos of the tree, check out this photo gallery from the New York Daily News.

2007-11 November, Optics and pop culture leds, lighting, optics and pop culture

Posted by Christina Folz, OPN Managing Editor

And now for more optics limericks taken from the Winter 1977 Optics News (the precursor to OPN).  In case you missed the first bunch, check out my earlier post and get inspired! OPN is now accepting submissions for a new limerick contest.  Send your submissions to opn@osa.org or post them  directly into the “comments” section of this blog. (Note about the second and third limericks: Peter Franken was the OSA president at the time of the contest, so that is why the poets chose to skewer him in their verses.)  

Experimental Technique
There is no faint penumbra of doubt
In the lab one should not be without
A light optical hammer
To give things a slam, or
That final adjustment—a clout.

—R.I. MacDonald
Ottawa, Canada

The election of Peter A. Franken
Was a shock, and the news slowly sank in.
He achieved this great fame
When he wrote down his name
On the ballot when filling the blank in.

—S. Bashkin
Tucson, Ariz.

There was a bright fellow named Planck,
Whose thoughts were exceedingly franck.
He showed us his verve
With the black-body curve,
Planck, for your constant, we thanck.

—J.E. Dennis
Rockville, Md.

An optical physicist, Franken
A gigawatt laser did sanction
To bake breakfast toast
Using third-order ghosts
At nine hundred one degrees Ranken.

—F.M. Phelps
Mt. Pleasant, Mich.

2007-11 November, Miscellaneous Optics, OSA osa, humor, scientists

Submitted by H.S. Kwok, OSA Fellow

Can anyone explain the following optical phenomenon?

I went to a garden in Guangdong over the weekend. They claim to have a window that can convert the outdoor garden scene from summer to autumn to winter depending on the position of the windows, which are made of blue tinted glass.

I’d like to share the three pictures that I took. The first one is the original summer scene, green trees and all.



The second was taken with one blue tinted glass window pane.



The scene does look wintery with the leaves appearing rusty in color and the white tops looking sort of like snow.

However, the most interesting is the third picture, taken with two overlapping blue tinted glass window panes. (The windows are of the sliding door type.)



The leaves turn red! The scene now looks like autumn. I cannot explain how the red color can come out with two blue filters. The leaves in the picture taken with two blue filters are redder than those in the picture taken with one blue filter. Strange. I saw it with my own eyes and took the pictures with a Canon DSC. Can someone please explain this?

H.S. Kwok, OSA Fellow
Hong Kong
 

2007-11 November, Miscellaneous Optics optics, puzzles, color