A Much Better Light Bulb

Optics researchers at the University of Rochester led by Chunlei Guo can turn regular incandescent light bulbs into power-sippers. This news after the Congress outlaws incandescent bulbs some years out.  Nothing is so dubious as mandating markets and closing off innovation and creativity.  But the rest of the world can rejoice, they can see better cheaper after dark than the dopey Americans who seem to have taken the central command economy to new heights of foolishness.

Using an ultra-powerful laser the new process could make a light as bright as a 100-watt bulb consume less electricity than a 60-watt bulb while remaining far cheaper and radiating a more pleasant light than a fluorescent bulb can.  Cheaper and better, great huh.  The global warming campaign is beginning to bite in unforeseen ways.

The laser process creates a unique array of nano- and micro- scale structures on the surface of a regular tungsten filament, the tiny wire inside a light bulb.  These structures make the tungsten become far more effective at radiating light.  Guo’s and his assistant, Anatoliy Vorobyev’s findings will be published in an upcoming issue of the journal Physical Review Letters.

Guo, associate professor of optics says, “We’ve been experimenting with the way ultra-fast lasers change metals, and we wondered what would happen if we trained the laser on a filament.  We fired the laser beam right through the glass of the bulb and altered a small area on the filament. When we lit the bulb, we could actually see this one patch was clearly brighter than the rest of the filament, but there was no change in the bulb’s energy usage.”  Now that’s a bright flash of intuition, too.  He could have saved an industry.

The fun numbers are in the key to creating the super-filament. Using an ultra-brief, ultra-intense beam of light called a femtosecond laser pulse, the laser burst lasts only a few quadrillionths of a second. To understand and quantify that kind of speed, consider that a femtosecond is to a second what a second is to about 32 million years.  So, during its brief burst, Guo’s laser unleashes as much power “as the entire grid of North America” onto a spot the size of a needlepoint. That intense blast forces the surface of the metal to form nanostructures and microstructures that dramatically alter how efficiently light can radiate from the filament.  It sounds a little like a hammer on the wire smoothing up the surface.

Back in 2006, Guo and Vorobyev, used a similar laser process to turn any metal pitch black. The surface structures created on the metal were incredibly effective at capturing incoming radiation, such as light.

Guo says, “There is a very interesting ‘take more, give more’ law in nature governing the amount of light going in and coming out of a material.”

Since the black metal was extremely good at absorbing light, he and Vorobyev set out to study the reverse process—that the blackened filament would radiate light more effectively as well.  Guo says, “We knew it should work in theory, but we were still surprised when we turned up the power on this bulb and saw just how much brighter the processed spot was.”

Now for this – in addition to increasing the brightness of a bulb, Guo’s process can be used to tune the color of the light as well. In 2008, his team used a similar process to change the color of nearly any metal to blue, golden, and gray, in addition to the black they’d already accomplished. Guo and Vorobyev used that knowledge of how to control the size and shape of the nanostructures—and thus what colors of light those structures absorb and radiate—to change the amount of each wavelength of light the tungsten filament radiates. Though Guo cannot yet make a simple bulb shine pure blue, for instance, he can change the overall radiated spectrum so that the tungsten, which normally radiates a yellowish light, could radiate a more purely white light.

Now for the photo folks, Guo’s team has even been able to make a filament radiate partially polarized light, which until now has been impossible to do without special filters that reduce the bulb’s efficiency. By creating nanostructures in tight, parallel rows, some of the light that emits from the filament becomes polarized.

Next, the team is working to discover what other aspects of a common light bulb they might be able to control.

Despite the incredible intensity involved, the femtosecond laser can be powered by a simple wall outlet.  The laser must have a very good capacitor set.  This suggests that when the process is refined, implementing it commercially to augment regular light bulbs should be relatively simple.

Getting the same amount of radiated luminosity for 60% of the power is a good deal.  Its not as good as the compact florescent, but close, and could well have saved the business in the U.S.  It still might if some clever lawyering and marketing is employed.  For those of us who are discomforted by the frequency of florescent that would be very good news.

Incandescent isn’t bad at all or inefficient when used correctly.  They are suitable whenever the furnace is running or you’re adding warmth to a space.  No energy is wasted.  I grant that incandescent bulbs aren’t a smart choice because they add heat – then we use energy to move it away, but for much of the populated world, incandescent is a fine idea and useful choice in lighting.

Adding the Rochester team’s innovation will make for a much better bulb that costs less to use and gives off better light.  It may even save consumers money and save on energy.  It’s just a shame that political pressure and weak character in politicians has loaded a new cost on consumers that will diminish these folks’ good work.  It won’t be as low cost as it could be and that’s exclusively a result of politicians doing what government has never done successfully.

Source: New Energy and Fuel

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