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-   -   White LED light harmful (http://www.diychatroom.com/f18/white-led-light-harmful-79353/)

Yoyizit 08-22-2010 10:38 AM

White LED light harmful
 
Nichia and other LED makers have details on this and on the precautions they take to minimize the damage from certain wavelengths.
This news is at least two years old but it's the first I've heard of it.

nap 08-22-2010 11:56 AM

there has always been a problem with all types of lights if they produce harmful IR or UV wavelengths. Each lamp type has dealt with the problem at some time in their use. Incandescents can easily be designed to produce IR wavelengths and fluorescents are notorious for producing UV wavelengths. HID lamps are also problematic in the UV range. I see no reason it is not possible to produce wavelengths of light via an LED that would be harmful. That is simply something the engineers have to deal with.

Yoyizit 08-22-2010 12:54 PM

The eye protects itself against the wavelengths and intensities found in sunlight. Apparently white LEDs produce blue light wavelengths at an intensity not found in the spectrum of sunlight and so the eye is fooled, and damaged.

This gets more and more complicated but we can't very well go back to using candles.

nap 08-22-2010 01:07 PM

Quote:

Yoyizit;489401]The eye protects itself against the wavelengths and intensities found in sunlight.
actually it doesn't. Ever try staring at the sun? Permanent damage can result. Especially during an eclipse the eye fails to protect itself.

Quote:

Apparently white LEDs produce blue light wavelengths at an intensity not found in the spectrum of sunlight and so the eye is fooled, and damaged.
and what wavelength would that be?

Quote:

This gets more and more complicated but we can't very well go back to using candles.
more complicated? for some reason you believe you are the only person to understand light? Tossing out such simplistic statements doesn't allow one to think much of what you are saying or the person saying it.

Yoyizit 08-22-2010 01:13 PM

Quote:

Originally Posted by nap (Post 489409)
1 and what wavelength would that be?

2 more complicated?
for some reason
Tossing out

1 440–490 nm
http://en.wikipedia.org/wiki/Blue
2 sorry to bother you.

Red Squirrel 08-22-2010 01:18 PM

What I'd worry about more is this:

http://www.wickedlasers.com/lasers/S...ies-96-37.html

Kids who have no idea about laser safety will go buying this pointing it everywhere at random.

You can blind an astronaut in the ISS with that thing. :eek: It can also burn your skin.

Yoyizit 08-22-2010 01:23 PM

Quote:

Originally Posted by Red Squirrel (Post 489417)
What I'd worry about more is this:

http://www.wickedlasers.com/lasers/S...ies-96-37.html

Kids who have no idea about laser safety will go buying this pointing it everywhere at random.

You can blind an astronaut in the ISS with that thing. :eek: It can also burn your skin.

"A laser diode is a laser where the active medium is a semiconductor similar to that found in a light-emitting diode. "

I guess the Army could use these to blind the enemy but that makes for bad press. Better to use microwaves to give them 1st & 2nd degree burns with only a minimal number of blindness cases.

nap 08-22-2010 01:31 PM

sunlight ranges from 290 nm to 3000 nm so yes, it does include light in the 440-490 nm range. As to intensity; there is no standard intensity developed by an LED and the intensity of sunlight varies with a thousand different variables. So, we need to know the intensity you are speaking of to be able to determine if the sun does in fact emit such wavelengths at a lesser intensity than your LED.

add to that that any wavelength of light can cause eye damage if great enough in intensity.

Red Squirrel 08-22-2010 01:37 PM

Come to think of it, I don't think they have a true white led yet. It's basically a very white shade of blue, or maybe a mix of colors. I've noticed that led flashlights do look somewhat white, but there is still a very small blueish tint to it.

Yoyizit 08-22-2010 01:43 PM

Quote:

Originally Posted by Red Squirrel (Post 489426)
Come to think of it, I don't think they have a true white led yet. It's basically a very white shade of blue, or maybe a mix of colors. I've noticed that led flashlights do look somewhat white, but there is still a very small blueish tint to it.

Red, blue and green sort of make "white". Adding a fourth color [maybe yellow?] gives you better fidelity but white light contains red, orange, yellow, green, blue and violet.
Does this sound like the color code for resistors?

nap 08-22-2010 01:50 PM

Quote:

Originally Posted by Red Squirrel (Post 489426)
Come to think of it, I don't think they have a true white led yet. It's basically a very white shade of blue, or maybe a mix of colors. I've noticed that led flashlights do look somewhat white, but there is still a very small blueish tint to it.

white light is produced by mixing actual colors of light. White itself is not a color but a combination of colors.

wikiquote:

Quote:

There are two primary ways of producing high intensity white-light using LEDs. One is to use individual LEDs that emit three primary colors[54]—red, green, and blue—and then mix all the colors to produce white light. The other is to use a phosphor material to convert monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same way a fluorescent light bulb works.

AndrewF 08-23-2010 11:06 PM

A little off topic, but we recently deployed 8 of these for a facility.

They are WICKED bright, and the whitest light I've ever seen.

http://www.etcconnect.com/product.ov....aspx?ID=22003

http://www.etcconnect.com/img/produc...ft_390x220.jpg

Yoyizit 08-24-2010 09:43 AM

Quote:

Originally Posted by AndrewF (Post 490258)
A little off topic, but we recently deployed 8 of these for a facility.

They are WICKED bright, and the whitest light I've ever seen.

http://www.etcconnect.com/product.ov....aspx?ID=22003

http://www.etcconnect.com/img/produc...ft_390x220.jpg

Can you post identifying info for this assembly? I'd like to look up the specs. . .power draw, lumens, spectrum, etc.
There's supposed to be someplace maybe in Norway where they use similar lights to light up ski slopes for nighttime skiing.

AndrewF 08-24-2010 02:07 PM

Quote:

Originally Posted by Yoyizit (Post 490393)
Can you post identifying info for this assembly? I'd like to look up the specs. . .power draw, lumens, spectrum, etc.
There's supposed to be someplace maybe in Norway where they use similar lights to light up ski slopes for nighttime skiing.

I can, not sure what I can take a picture of that isnt included in the manufacture specs.

http://www.etcconnect.com/product.do....aspx?ID=22003


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