On Monday, September 22, 2003, at 11:13 PM, Jinx wrote:
> none make explicit warnings about LEDs, particularly any
> requiring warning labels, eg

The part we're using now is from ETG... the ETG-5UV405-30.  At the=20
bottom of their data sheet they say:

CAUTION: EMITS ULTRAVIOLET RADIATION!!
=B7  This device radiates intense ultraviolet (UV) light when operated.
=B7  Exposure to UV radiation can be harmful to your health. Protect =
your=20
eyes and skin during operation.
=B7  Do not look directly at the device during operation. Exposure to UV=20=

light, even for a brief period, can damage your eyes.

However, I emailed ETG asking them about the danger and they won't be=20
specific.  They just say "probably not a good idea to look at the light=20=

too long".

>  Your artwork will be visible because the UV has been
> transformed into visible wavelengths, but it's hard to say what level
> of UV reflects unaltered - I'm guessing not much.

In this case, the LEDs are shining up through large quartz crystals,=20
which apparently transmit UV easily.  So we're not looking directly at=20=

the LEDs, but the light is still quite bright as it's transmitted up=20
through the crystals.  Even though these are called "UV" LEDs and have=20=

a narrow band (400-410nm) the light is directly visible as violet light.

> Compared to an
> arc welder (which is quite easy to get flash burns from) or a=20
> germicidal
> lamp, I'd have thought LEDs wouldn't be a concern in a setting such
> as your.

Me too...

> But I'm not a doctor or FDA researcher

For anyone interested, here's what the interesting part of the FDA=20
regulations on UV lamps say:

     (ii) The spectral transmittance to the eye of the protective =
eyewear
required by paragraph (c)(4)(i) of this section shall not exceed a value
of 0.001 over the wavelength range of greater than 200 nanometers 320
nanometers and an value of 0.01 over the wavelength range of greater
than 320 nanometers through 400 nanometers, and shall be sufficient over
the wavelength greater than 400 nanometers to enable the user to see
clearly enough to reset the timer.


Which _implies_ that >400nm is basically safe.  Since these LEDs peak=20
at 405nm, but produce 400-410nm... I'm still not sure what to make of=20
it all.

Thanks to everyone for the pointers and suggestions!  This list rocks!

darren

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