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Scientist hope to put LEDs to work in brilliant new ways

LEDs, light emitting diodes, are a very old invention, with the first visible-light diode being invented in 1962.  They consist of a junction of semiconducting material, such as a silicon or gallium compound.  However, scientists today are looking to teach this old dog some new tricks, and putting LEDs to work in a plethora of creative uses.

The magic is in the material.  While LEDs have been around for a long time, new and exotic materials are being used and older materials are being tweaked and reformulated to provide, a wider range of colors, brighter light, and higher efficiency.

The result is that LEDs may soon be permeating our lives in new ways.  LEDs are already invading the automobile headlight industry and are in high demand due to their superior life and brightness. 

Now one place scientists are looking to plant the LED is in the home.  Tungsten lightbulbs have a very low 5% efficiency, compared to modern LEDs, which have around a healthy 40% efficiency.  The result is power savings, increased brightness, and superior life.  Obstacles standing in the way of this development are the still higher cost of LEDs and the fact that LEDs' white light has much more blue than sunlight or natural bulbs.  However, these obstacles are fading as costs slowly drop and scientists develop better material blends to provide more yellow to the LED's emissions, making for a warm light that would be welcome in many a household.

Scientists are also looking to put tiny LEDs to a new use in the lab and eventually in commercial internet connections -- quantum cryptography.  Tiny streams of photons in the system would pass from the LED to the a detector.  Any interception of the beam (ie. snooping) would result in the signal being altered, as per the observer effect.  Such a system, when properly implemented would be in theory immune to any sort of malicious interception between the sender and the receiver.

Yet another use for the little lights has been proposed by scientists -- this one with promise of bringing new high-tech hope to impoverished regions.  One of the world's largest problems is the lack of clean drinking water in third-world nations.  Chemicals can be used to treat drinking water, but they are often expensive, toxic, and require a large amount of infrastructure.  A frequently used alternative is high-energy UV light known as "deep UV", emitted from special UV bulbs.  Passing a beam of this light through water kills most bacteria and destroys most viruses cleanly and simply.  The issue with this system is bulbs constantly need to be replaced and are two bulky for small scale use.

Scientists feel the answer is deep UV LEDs.  While they are still working on perfecting the materials, researchers,  such as Dr Rachel Oliver, an LED researcher from the University of Cambridge, think it is just a matter of time before the optimal combination of materials is found. 

"Deep-UV can't be made from the combination of materials we're used to, although I certainly think it's possible," Dr. Oliver stated.

Dr. Oliver is among many researchers striving to put LEDs to use in new and creative ways.  She sees LEDs being commercially implemented in the aforementioned uses within 10 to 20 years.

For now these prospects still remaining cost prohibitive and are dependent on material breakthroughs, but the future sure looks bright for these little devices.  And companies are looking to put LEDs today to a different and even more outlandish use -- clothing -- every airport security officer's worst nightmare

Whatever their form, LEDs are transforming the way we light and see our world.

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home light
By TMV192 on 12/15/2007 11:26:26 PM , Rating: 2
However, these obstacles are fading as costs slowly drop and scientists develop better material blends to provide more yellow to the LED's emissions, making for a warm light that would be welcome in many a household.

I personally don't like the "warm light", I bought a small cool white 24 LED light bulb and I found it much more pleasant on the eyes. Right now, the larger bulbs are too expensive, so I went with CFL. I use mostly 5000K and 4100K which is not too warm

RE: home light
By Ringold on 12/16/2007 12:25:21 AM , Rating: 5
I can't stand that sort of light myself. Similar reason why I don't go for CFL, except in some lamps that have yellow whatcha-call-'em around them, that provides a decent effect. The lag time to full brightness totally rules out certain applications, like stair wells, too.

No, they get some warm colored LED's that spread light over a wide angle and then I'll jump on this particular green bandwagon whole-heartedly. Low energy use, long life, and then good output quality -- no reason not to at that point.

RE: home light
By Bonesdad on 12/16/2007 12:29:14 AM , Rating: 2
in my experience, the lag time you mention doesn't really apply...true the CFL are dimmer when you flip them on...but not so dim you couldn't see going down the stairs.

RE: home light
By zsdersw on 12/16/2007 8:04:44 AM , Rating: 2
Time-to-full-brightness is also not something *all* CFL's suffer from. I have some in my kitchen that are as bright when you flip the switch as they are after being on for 5 minutes or an hour.

RE: home light
By FITCamaro on 12/17/2007 1:27:10 PM , Rating: 2
Or you just wait 1 second for it to fully come on.

The only downside for some CFL bulbs if I recall is you can't use them with dimmer switches. But I don't have any of those anyway.

RE: home light
By blaster5k on 12/16/2007 10:25:57 AM , Rating: 3
The other problem with CFLs is that their lifespan is a function of how many times they are turned on and off as opposed to just how long they are used. Incandescent bulbs, despite their higher energy usage, are still a better solution for lights that go through rapid on/off cycles.

I don't think LEDs have this problem either, but I could be wrong.

RE: home light
By mindless1 on 12/16/2007 11:28:24 PM , Rating: 2
Compared to LEDs, even incandescent bulbs are terrible for rapid on/off cycle lifespan. There is no other light source I'm aware of that is even tolerant of 1/10th as much cycling as an LED. The problem with incandescents lies in high inrush current until the filament is heated.

RE: home light
By TomZ on 12/17/2007 3:10:07 PM , Rating: 2
Incandescent couldn't be all that bad for cycling. After all, they've been used for decades in traditional "cycling" applications like stoplights, railroad crossings, industrial indicators, automotive turn signals, etc. etc.

RE: home light
By mindless1 on 12/18/2007 4:27:08 AM , Rating: 4
In a world that wasn't concerned about efficiency, yes.

Today, to reach high efficiency it means using switching supplies with high frequency pulses of power.

That is, if one uses LEDs. Consider that for stoplights, many have already been replaced because their failure rates at the on/off duty cycle were costing more than the investment in LEDs to replace them.

How bad they are is just relative, even a turn signal goes through a mere few dozen thousand cycles while an LED can tolerate than in one single day, and keep running for a few dozen years if all the supporting infrastructure remains viable.

LEDs have no equal in cycling. the only problem is when penny pinchers or foolish designers try to overdrive them to conserve space, or construction costs of lighting fixtures. Overdrive an LED enough and the energy savings wasn't of much importance, relatively, compared to energy to replace it and that cost, but as with all industries there is enough interest that the body of knowledge will soon enough allow even average joe customers to ask the hard questions about how the specs were achieved and demand a standardization beyond the discrete part output, rather specs about the achieved performance as implemented in the particular device.

I suspect even railroad crossing lights are being replaced by LEDs when the local budget allows, but on the other hand it wouldn't make much sense to do so until the stockpile of old incandescent bulbs were used up.

RE: home light
By mindless1 on 12/16/2007 11:33:30 PM , Rating: 2
I wonder if you are only considering one sample or bulbs of yesteryear. There are a reasonable number of CCFL bulbs today that produce a reasonable hue and while they may not be at a perfect hue or 100% brightness immediately after being turned on, they are reasonably near that within a second or two, are certainly suitable for a stair well or wherever, except outside as most are not designed to withstand extremes of hot or cold, or water for that matter.

RE: home light
By masher2 on 12/17/2007 2:01:03 AM , Rating: 2
Color rendition and startup time has certainly improved on CFL bulbs, but they still have other issues. Some people (my wife among them) are very sensitive to the flicker effects. CFL bulbs also put out a fair amount of ultraviolet, which can cause problems for those sensitive to it.

RE: home light
By SandmanWN on 12/19/2007 10:26:38 AM , Rating: 2
Yet on the flip side I personally enjoy the slow up time of CFL especially in the morning when waking up. It doesn't seem to hurt my eyes nearly as much as the instant on effect with incandescents.

What is a fair amount of ultraviolet anyway? Is it anywhere near what your eye takes in typically from just being outside? If its not, then that isn't much of an argument, especially with the few people it actually affects and the alternative light sources available.

RE: home light
By timmiser on 12/16/2007 12:38:08 AM , Rating: 2
I agree with you. I'm a big fan of true white light that much more closely resembles natural sunlight. I have long ago replaced all my inhouse bulbs to CFLs and have been enjoying the energy savings.

> 60w of light for 13w

RE: home light
By Lazarus Dark on 12/16/2007 2:21:05 AM , Rating: 2
I was about to say the same thing. I hate yellowish light. It hurts my eyes after long periods. I much prefer blue to white light. When I build my own house, it will definately use all led lighting.

RE: home light
By Haven Bartton on 12/17/2007 3:29:30 PM , Rating: 2
I've never quite understood this myself. As I was taught, sunlight is far "bluer" than our normal indoor lighting. Isn't is the difference of 5400K and 7200K? We went over this in film school, but I can't recall the exact numbers.

Shouldn't these LEDs just be better mimicking sunlight?

RE: home light
By masher2 on 12/18/2007 3:32:32 PM , Rating: 2
The issue with LED's isn't the amount of "blueness", but rather the fact that "white" LEDs don't really emit white light at all. The most common sort use phosphors to generate two different frequencies of monochromatic light, which our eye perceives as white. Despite that, the light is deficient in all the other frequencies, which typically makes for poor lighting.

RE: home light
By mindless1 on 12/23/2007 10:24:50 PM , Rating: 2
LEDs come in different color temp even for the same "white" part. The highest efficiency tend to be a more blue color, since blue is the actual light produced then (usually) a yellowish phosphrous coating converts to other spectrum. The conversion isn't 100% efficient so the further from blue it drifts, the more light is lost.

"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -- Isaac Asimov

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