Regular Light Bulbs Made Super-Efficient with Ultra-Fast Laser
May 29, 2009
Chunlei Guo stands in front of his femtosecond laser, which can double the efficiency of a regular incandescent light bulb. Credit: University of Rochester
(PhysOrg.com) -- An ultra-powerful laser can turn regular incandescent light bulbs into power-sippers, say optics researchers at the University of Rochester. The 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.
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—and theses structures make the tungsten become far more effective at radiating light.
The findings will be published in an upcoming issue of the journal Physical Review Letters.
"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," says Chunlei Guo, associate professor of optics at the University of Rochester. "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."
The key to creating the super-filament is 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 get a grasp of that kind of speed, consider that a femtosecond is to a second what a second is to about 32 million years. 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 needle point. That intense blast forces the surface of the metal to form nanostructures and microstructures that dramatically alter how efficiently can radiate from the filament.
In 2006, Guo and his assistant, Anatoliy Vorobeyv, 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.
"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," says Guo. 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.
"We knew it should work in theory," says Guo, "but we were still surprised when we turned up the power on this bulb and saw just how much brighter the processed spot was."
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 he'd already accomplished. Guo and Vorobeyv 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.
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 light that emits from the filament becomes polarized.
The team is now working to discover what other aspects of a common light bulb they might be able to control. Fortunately, despite the incredible intensity involved, the femtosecond laser can be powered by a simple wall outlet, meaning that when the process is refined, implementing it to augment regular light bulbs should be relatively simple.
Guo is also announcing this month in Applied Physics Letters a technique using a similar femtosecond laser process to make a piece of metal automatically move liquid around its surface, even lifting a liquid up against gravity.
Source: University of Rochester (news : web)
Nov 21, 2006 |
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This new technology will be excellent for auto lights.
and Compact Fluorescent bulbs actually give off some rather nasty UV and should not be used to work under, unless you want skin cancer. this is not to mention the mercury content that makes disposal so much of a problem.
LED is the only safe option available at the moment, unfortunately a very expensive one.
I dont think artificial UV light has nearly enough power to cause skin cancer. Can you back it up with a source?
Sunlight, and the closer to sunlight, the better. Our circadian clocks are regulated by it (especially mens'), plants grow best in it, digital cameras take the best photographs in it. Even lamp "temperature" is a very vague description of wildly irregular coverage across the visible spectrum. Firelight has a romantic association but the fluorescents are critically deficient in another way, too, in that they send rooms into darkness 60 times a second. This was supposed to be undetectable for humans, but that turned out not to be the case on the subconscious level.
Not for me, it isn't - they give me the most awful migraines, and I loathe the greenish sickly light they give out.
2 last things, quit whining about "light quality" its all in your head. and, ... I'm tired of vulvox do they even have any products or do they just put out press releases.
Old fluorescent tubes with heavy ballasts do flicker at twice the grids frequency, either at 100Hz (Europe) or 120Hz (USA etc). Newer fixtures like CFLs have build in electronics that make them flicker above audible range somewhere like 30000Hz. That is not noticeable to human eye. Just a reminder, your television also flickers at 50/60Hz if it is not one of those new 100/120Hz or more frames per second models.
FWIW, IIRC, to help with sleep disturbance, melantonin cycle etc, now being suggested we have 'harsh' blue-ish lighting during day, then shift to 'warm' orange-ish lighting in evening-- Just like natural sun-light.
It'd be nice if "science advisors" (who are often, so it seems, ambassadors for all kinds of junk science) would ask around before foisting technology off on us, like the new "digital" TV, fluorescent lights in standard fixtures, etc.
The only good news is that it appears that LED's, which may not share some of the CFL's disadvantages, may drop in price enough to a better choice. And, although the LED is a little sloppy, if you have a couple dozen of them faking a big light bulb, you could "tune" the bulb's color a bit rather easily just by slightly different specs for some of the LED's....
Just IMHO, of course.
The sun isn't 2700 K. Score one for "daylight" fluorescent lighting.
Better gradually dim your light in the evening and not use your computer(or anything else bright) several hours before bed then.
Me? Not a chance.
Most species do very well with hideous high pressure sodium lamps.
This has never been true. Crappy fluorescent lighting flickers at twice mains frequency; your typical fluorescent lighting with electronic ballast flickers at some inaudible frequency above 20 kHz.
Normal light bulbs flicker quite a bit at double mains frequency because the wire isn't thick enough to stay at a steady temperature.
Wherever dirt cheap and able to tolerate tens of thousands of cycles is preferable to efficiency(bath room, garage and other places used frequently for short periods of time)
How much use can the nanoscale structures take before breaking down? And, given the possible breakdown, will energy consumption increase?
If the lifetime of the bulb is much less than its peers, then it will not fare well in the market.
Still, might be a source of special-purpose bulbs.
At first, I was pleased that the bulbs started out dim but warm up to full brilliance in 3 or 4 minutes. In a bathroom, when you wake up at night, you don't want to be hit with the full intensity when you turn on the switch.
But then I realized that the reason was the gas was warming up in the bulb... thermal expansion => stress => short life!
I suspect all the government mandated tests do not cycle the bulbs realistically.
Another question: How much extra energy is wasted these days because people figure the bulb is efficient... thus they don't bother to turn off their lights as often? I find myself thinking that way... I suspect we all do.
Must stop typing now... getting too tired from pedaling this electric generating cycle the powers the computer. :)