Yeah,i can not agree with you any more about I’d spend a few minutes with a startup claiming to have the next big thing in LED lighting. I really impressed by your post. http://www.safeffxivgil.com| http://www.gw2.us
Absorption within the light guide mean that any "light guide system" lm/Watt figure is going to be less than the LED source.
Keeping optical path lengths short, Coupling of light from the LED into the light guide and re-cycling any light that would otherwise escape from the wrong part of the light guide are all important.
Maintaining efficiency and uniformity over larger light guides becomes exponentially more difficult!
twk's comment is quite appropriate. LED lighting is pretty expensive right now. I built something vaguely similar to twk's project, and I suspect that we made similar cost projections. I do some photography of costume jewelry: I wanted large, uniform lighting fixtures. LEDs are fabulous: easy to control brightness, and to control the change in brightness across the 17" by 24" fixture; color can be modified, runs (relatively) cool. But the final design consisted of 3 dual tube 24" fixtures with T12 bulbs. Several color temperatures are available, and there was no other way to get the intensity levels that I wanted at a cost I could afford. LEDs are on my menu, but I have to wait until they are far less expensive. That time is coming, I suspect.
I recently completed a home shop building and illuminated it with 26 two tube T8 fluorescent fixtures. These were chosen based primarily on cost. They cost me less than $30 each including lamps. I note that Cree is selling where the initial cost is not a problem both because of extremely high maintenance cost as well as relative insensitivity to cost in the overall sense. I see no comment here about the cost of this approach. I would love to install this or some other LED based illumination and am capable of even building the fixtures if industry has not yet done so. Thus far I have not discovered ANY LED approach (either fixtures or parts)that comes closer than about ten times the basic fluorescent. I think you folks have a very long way to go to begin to displace long standing illumination types but I cheer you on with enthusiasm while you get your market from those with big pockets hoping someone finally brings the cost in range for plain old folks.
I wonder how Oree's products, especially LightCell, will catch on in the green energy market. This is fantastic technological advancement. Congratulations to your team! Do you partner with Cree?
My colleague who works at a similar company tells me the following..."Cree, is a medium-size company that is quickly expanding with the green energy boom. Last quarter the company hit 3/4 billion dollar revenue mark and is well on its way to be the leader in the LED industry, that is estimated to grow 5 fold in the next 5 years. Cree manufactures 40% of the public lights in Las Angelos, 100% of the public lights in Alaska, and 80% of the lights in North Carolina. In addition Cree's LED lighting was used to light the Olympic Cube in the Beijing 2008 Olympics. That displayed alone used 440,000 of our lights!"
From the market opportunity for Oree's planar technology to the potential dangers of LED lighting, the feedback here has been fantastic, thanks guys.
I'm moderating an Ask The Experts virtual panel (go to www.eetimes.com/lighting) this coming Thursday (August 26th.). The focus is on LED selection, design and implementation challenges and solutions, and the panelists will be experts from Digi-Key, who deal with these issues every day and are primed and ready to answer all these questions, and more.
Thanks to the feedback here, I'll be adding LED safety and the potential for planar lighting and other emerging technologies, to the list of up-front questions. If you have more, let me know here, or better again, log in this Thursday to the panel and them there, first hand.
'See' you there!
It is encouraging to see how many of the commenters here are concerned about the safety of the light emitted by LEDs. This is particularly important for young eyes because our lenses become yellowish only as they age. They let through most of the most damaging wavelengths in the "blue-light-hazard" region until our late teens or early twenties.
Virtually all fluorescent lamps emit their strongest radiation spike at 435.8 nanometers which is in the blue-violet region and right in the middle of the wavelength region between 430 and 440 nm which the U.S. Occupational Safety Guidelines have determined to cause the most damage in all mammalian eyes.
For a discussion of these risks, see "Is fluorescent light safe for children's eyes?" at http://retinopathyofprematurity.org/maculardegeneration.htm.
These dangers have been widely ignored for fluorescent lamps, but the concerns raised here about the safety of light from LEDs justify the hope that this dismal blindness to the blinding potential of fluorescent light will not carry over into the evaluation of LEDs where the offencing wavelengths may be easier to avoid.
A) Somebody tell me about the "unseen" radiation that one would get from an LED or LED/phosphor system. These things are so useful that if they gave off UV A they'd still have a use. Of course, I don't want to sit at home reading with sunglasses on. ;-)
B) Oree: make some with polarizers in the upper layer. Large sheets of light are great for product photography, and better still, polarized light give the photographer some interesting options. At the moment, I have to buy 17" wide sheets of polarizing film. Sure, not the largest market, but...
Blog Doing Math in FPGAs Tom Burke 15 comments For a recent project, I explored doing "real" (that is, non-integer) math on a Spartan 3 FPGA. FPGAs, by their nature, do integer math. That is, there's no floating-point ...