LED lights in exhibition cases

Karen Potje <kpotje [at] cca__qc__ca> writes

>For the same CCA exhibition described above it has been suggested
>that we use white LEDs on the *inside* of an exhibition case as the
>light source for a display of documents.  UV light must be excluded
>and the light level must be low (50 lux).  Is information about the
>UV content of white LEDs available?  Is it possible to control the
>light levels and ensure that they remain at a steady 50 lux  over
>the course of a long (8 month) exhibition? Do LED lights start out
>bright and then get dimmer over time?  The designer of the show
>suggests that LEDs are cool--there will be no heat build up in the
>completely enclosed exhibition case.  Is this the case?  Are LEDs
>being used by other museums to light exhibition cases?

White LED's are a relatively new technology, and a lot of
information is available on the Web.  Searching for "White LED"
turned up a lot of sites, including a particularly interesting one
at URL:https://www.netdisty.net/ds/bf304-yw/default.asp> for a
manufacturer in California.  They mention colors, but don't seem to
have spectral curves.

LED's don't seem to generate any heat.  White LED's are, however, a
hybrid device where the beam from a blue LED hits a phosphor to
generate the white light.  There are different colors of white LED's
depending on the phosphors and their thicknesses, and within 4
identical LEDs I bought from Radio Shack there seem to be at least 2
different colors.

I have a flashlight with a blue LED (bought by mistake--I wanted a
white one) and it is very bright.  I noticed that it excites
fluorescent material (a fluorescent orange Avery label), so it may
have a UV component.  Some good spectral emission measurements on
these devices would be interesting.



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                  Conservation DistList Instance 17:5
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