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White laser light found to be just as easy on the eyes as LEDs

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October 27, 2011

Researcher Jeff Tsao examines the set-up used to test diode lasers as an alternative to LE...

Researcher Jeff Tsao examines the set-up used to test diode lasers as an alternative to LED lighting (Photo: Randy Montoya)

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With incandescent light bulbs in the process of being phased out around the world, LEDs are one of the most promising technologies for taking over our day-to-day lighting needs - they use less energy, provide more light, contain less toxic substances, and are tougher than incandescents. That said, they may not be the one and only best choice. Lasers are even more efficient than LEDs at high amperages, although scientists have long believed that the quality of white light produced by diode lasers would be unpleasing to the human eye. According to a study recently carried out by Sandia National Laboratories, however, the human eye appears to like their light just fine.

To create white light, the beams of blue, red, green, and yellow diode lasers are merged, combining their four very narrow-band wavelengths. Sunlight, by contrast, incorporates a much wider light spectrum, with no gaps between wavelengths - even LEDs have a spectrum that is ten times wider than that of white laser light. For this reason, it had been assumed that people would find laser light unpleasant.

Four laser beams -- yellow, blue, green and red -- converge to produce a warm white light ...

The study was performed at the University of New Mexico's Center for High Technology Materials. A total of 40 volunteers were individually shown two identical bowls of fruit, set side-by-side but in separate chambers. Each bowl was randomly lit by warm, cool, or neutral white LEDs; a tungsten-filament incandescent light bulb; or by the four combined diode lasers. In each case, the volunteers had to state which type of light they preferred, without knowing which was which - the people administering the tests were also unaware of what particular combination each volunteer was viewing.

The volunteers came from a wide range of age groups, with each person having to choose a total of 80 times between two types of light.

When all was said and done, it turned out that there was a "statistically significant preference" for the laser light over that of the warm and the cool LEDs. There was little difference between preferences for the laser, neutral LED or incandescent lights.

Laser lighting is on the left, with incandescent on the right - which do you prefer? (Phot...

Laser-based lighting (left) and incandescent lighting (right)

While the apparent acceptance of the laser-based light is surprising, it doesn't necessarily mean that such technology will be usurping LEDs any time soon. Diode lasers are still more expensive to produce than LED bulbs, plus the yellow and green lasers aren't yet efficient enough for commercial use.

Sandia's Jeff Tsao, who proposed the experiment, has suggested that it might instead make sense to combine the two technologies - creating white light using blue and red diode lasers with yellow and green LEDs, for example. The combinations of the different colors could then be tweaked by users, to produce multiple color temperatures of light from one source.

In the meantime, BMW is already planning on using blue diode lasers to produce white light in the headlights of its i8 concept car.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
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5 Comments

I VERY much like the idea of this and would just love to see either the diode laser or the L.E.D. tech come to fruition sooner rather then later, but I would like to point out that just because there are "laws" set to take effect to eliminate incandescent bulbs I think they wont be going away as soon as people think? Plus there are some legitimate reasons one would want to have the hot inefficient incandescent bulbs in certain places, such as very cold country where traffic light and street lights would want there heat to melt the snow and ice off of them so they can even be seen, this has already proven to be a problem where L.E.D. traffic traffic lights are filling up with snow and not staying visible in colder climates when there is no residual heat to melt them free.

mrhuckfin
27th October, 2011 @ 04:36 pm PDT

LOL - laser light company designs a trial in which a "statistically significant preference" for their own product is established.

If the entire concept isn't dubious enough, they go as far as to tell us *some* numbers (eg: test repetition of 80 times), and then conspicuously omit *all* the important information (the actual test result numbers).

Not only that, I personally absolutely despise L.E.D. lighting. It's immediately recognisable to me, and strains my eyes noticably. Maybe these people chose specific test subjects to do their "trial" on, deliberately omitting everyone who has any kind of difficulty focussing on wavelengths at the blue end of the spectrum, like me? Not only that, the "warm" feeling of a good halogen usually beats all other lightng "hands down" (ask any industrial interiour lighiting engineer). People don't look at fruit bowls, they inhabit rooms. The test seems to have been carefully designed to encourage the outcome they want, and did so out of the realms of any normal expectable use case (unless you happen to be a fruit shop, but even they use extra special lighting that makes their produce look better already, so that's never going to be a market for these lights anyhow).

christopher
27th October, 2011 @ 09:54 pm PDT

re; mrhuckfin

They all ready make a thermostat controlled heating element for LED traffic lights in cold climates.

re; christopher

Perhaps by combining and balancing four colors of lights They fixed the problem that you have with LED generated light.

A bowl of mixed fruit is about as good of a test subject for testing light sources as you will be able to find.

Your statement that there would never be a market for these lights anyhow, Is the perfect topping for your ridiculous rant.

Slowburn
28th October, 2011 @ 04:25 am PDT

@christopher,

Huh? Since when is Sandia National Laboratories a "laser light company"? They're a Federal laboratory which doesn't make any products.

Gadgeteer
28th October, 2011 @ 05:01 am PDT

to mrhuckfin, there is already a means to eliminate the ice and snow from traffic lights, it's called hydrophobic coating. When this product is sprayed on a lens, nothing sticks to it, it will be used on bridges soon, to keep them from rusting, and from ice forming on them.

Remember, "Technology is the engine - Creativity is the fuel". So don't sell anything short, until proven by demand.

alfred knows
28th October, 2011 @ 10:25 am PDT
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