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Lasers and Lightbulbs

ChrisC

Critical Thinker
ChrisC
Joined
Dec 27, 2005
Messages
466
I thought this was pretty neat.

http://www.rochester.edu/news/show.php?id=3385

Normal 100 watt incandescent bulb = about 1720 lumens* = 17.2 l/w
Normal 60 watt incandescent bulb = about 860 lumens* = 14.3 l/w
Laser-treated incandescent = better than 28.6 l/w (1720 lumens at 60 watts), plus ability to tune colour.

Best part: Awesome frickin' lasers and incredibly tiny lengths of time. :D

* first hit when I googled "100w incandescent lumens" http://pacificpower.apogee.net/res/relinca.asp
 
That's pretty amazing. Just when everybody's resigned to phasing out incandescent bulbs and replacing them with LEDs, these guys show up with a way to improve the incandescent bulbs.
 
According to Wikipedia, CFLs generally get around 60-70 lm/W, while LEDs can easily get over 100 lm/W.

So yeah, nice effort, but not anywhere near good enough to compete with other technology on efficiency grounds.
 
Cuddles said:
According to Wikipedia, CFLs generally get around 60-70 lm/W, while LEDs can easily get over 100 lm/W.

So yeah, nice effort, but not anywhere near good enough to compete with other technology on efficiency grounds.
Click to expand...

The LED values are a bit misleading. They actually are less efficient than CFL's because they only broadcast light in a small cone. CFL's act as spherical emitters, essentially. LED's are far better for many applications (flashlights, for instance) but for overall lighting, they are less efficient than a CFL. In their favor is the fact that they almost never burn out...
 
jasonpatterson said:
In their favor is the fact that they almost never burn out...
Click to expand...

They're also instant-on, work in cold environments, and can survive being dropped much more easily. They don't need to be more efficient than CFL's to compete, but given that they're also far more expensive any typically not as bright (I've never seen a 100-watt equivalent LED), they're not really ready for general purpose lighting yet
 
It sounds like the only test they did so far was on a partial amount of filament. I wonder if the rest of the filament glowed less because of the treated segment? I do not have much understanding of the science involved with light bulbs, wondering if anyone can clear this up.

"even lifting a liquid up against gravity." I think we have an MDC applicant! Oh, wait, my pant legs do that already when I step in a puddle.
 
I agree that CFL's are still probably the best bet for general lightbulb replacement. I just thought it was a cool application of lasers on a common and very old technology.

I use a lighting system on my bicycle that I built from Cree XR-E diodes. Excellent application for them, IMO. Something to consider about LED lumen ratings from datasheets is that they don't take into account losses from optics (about 15% for a 20mm wide-angle optic from Carclo, for example) or losses from drivers and any power conversion necessary. Off the top of my head, I should be getting about 45-50 l/w including losses. Modern LED's are a pleasure to work with and have many merits, but they're not perfect for every situation.
 
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jasonpatterson said:
The LED values are a bit misleading. They actually are less efficient than CFL's because they only broadcast light in a small cone.
Click to expand...

I'm not sure what you mean. Lumens are a measure of the total light output in all directions, not a measure of the brightness in a particular direction.
 
Huh, neat work. But I wonder how long their microstructures on the tungsten surface will last. The metal evaporates slowly over the lifetime of the bulb, and the microstructures may be the first to go.
 
Another interesting tidbit:

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.
Click to expand...

This has great potential for LCD displays. Most displays either lose a lot of light due to wasting one polarization, or need fancy optics to recapture that light. This could eliminate a lot of problems, and thus reduce the cost of LCD displays significantly.
 
jasonpatterson said:
The LED values are a bit misleading. They actually are less efficient than CFL's because they only broadcast light in a small cone.
Click to expand...

No. As 69dodge says, that does not make them any less efficient. Less useful in some applications maybe, but efficiency as defined by the ratio of useful power out to power in is unquestionably better for LEDs (on average that is, there are certainly inefficient LEDs that are worse than many CFLs).
 
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