# UV free LED required



## oplonk (Mar 27, 2014)

Hi,
I have a friend who has an allergy to sunlight. Specifically to the UVa wavelengths. Because of this she's forced to use halogen bulbs but would like to be more eco-friendly (and also make a long-term saving on buying new bulbs). Fluorescents are out (apparently they trigger it in her), so I was wondering, are there any home LED bulbs available that emit zero UV light.

Exact requirements:

Available for retail in the UK (or online).
Bayonet Cap
Regular ceiling home light fitting
*Absolutely no UV wavelengths emitted.*

I'm happy to double check with manufacturers, but pointers would be a good start.
Thanks!


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## FRITZHID (Mar 28, 2014)

The biggest issue you're going to have with this is, in order to make a "white" led, they use a uv or near uv led chip and shine that through a phosphor that changes that uv into a whiter light, but some uv always gets through, you MAY be able to get some white LEDs and then place those behind a uv absorbent lens, but you'd want to try that before going full house.


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## oplonk (Mar 28, 2014)

Thanks for the information. I guess we can rule out that sort of LED. However wikipedia suggests there are three ways of creating white light:




> There are three main methods of mixing colors to produce white light from an LED:
> blue LED + green LED + red LED (color mixing; can be used as backlighting for displays)
> near-UV or UV LED + RGB phosphor (an LED producing light with a wavelength shorter than blue's is used to excite an RGB phosphor)
> blue LED + yellow phosphor (two complementary colors combine to form white light; more efficient than first two methods and more commonly used)




So are there any bulbs that use one of the other (above green) methods?


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## AnAppleSnail (Mar 28, 2014)

oplonk said:


> Hi,
> I have a friend who has an allergy to sunlight. Specifically to the UVa wavelengths. Because of this she's forced to use halogen bulbs but would like to be more eco-friendly (and also make a long-term saving on buying new bulbs). Fluorescents are out (apparently they trigger it in her), so I was wondering, are there any home LED bulbs available that emit zero UV light.
> 
> Exact requirements:
> ...



White LEDs produce "Nearly" no UV output. Fritz is correct in stating that they use a blue emitter behind a phosphor (Which transforms blue photons into other colors to make white light). High-intensity royal blue has some eye hazards, and can cause eye fatigue like UV. I DO NOT know if a UV sensitivity will be set off by the blue component in white LED light.

I assume your friend buys halogens with a UV filter. The hot filament produces light in the visible, IR, and UV ranges. The UV and IR photons can be absorbed by filters to leave visible light passing. The same could be done with LED lighting, unless the LED light, with higher blue content, causes a problem. I suggest medium-CCT, high CRI LEDs. Tailstand an LED flashlight in a room with her to test for irritation.


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## schizeckinosy (Mar 28, 2014)

Back in the day, weren't "white" led fixtures available that used a mixture of colored emitters, and no phosphors? I would think that those would produce no UV. I'm just going on vague recollection here...


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## Ken_McE (Apr 3, 2014)

Spray the bulb with one of those UV protectant products? Buy UV block sleeves and move them from bulb to bulb?


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