[NHCOLL-L:1556] display lighting

[Tamar Danufsky]

Many thanks to those who responded to my post.

I received the following response offlist:

Tamar

---------- Forwarded message ----------
Date: Mon, 1 Apr 2002 12:46:52 -0500
From: Larry_Bowers at nps.gov
To: td6 at humboldt.edu

Barbara forwarded your questions for me to answer as I am involved heavily
in museum lighting forthe Park Service.

The choice of lighting depends greatly on a number of factors, to include
exhibit case design, cost, artifacts enclosed, etc.  Light affects objects
in three ways: total illumination (footcandle) levels, ultraviolet
radiation, and infrared radiation.  The best lighting for an exhibit case
containing natural history specimens is, without a doubt, fiber optics.
The cases can be lit with no ultraviolet and infrared components of the
spectrum.. If the illuminator (light source) is sufficiently separate from
the exhibit environment, the only concerns you then have are aesthetics and
footcandle levels.  Filtered fluorescent lighting can work fairly well if
the light attic is sealed, and if you wish to have no directional lighting
at all.  Yes, they can generate enough heat to damage natural history
specimens.

"While incandescent lights are low in UV radiation, they generate heat.
Has  anyone had experience or does anyone know what the characteristics
are for LED lighting?  LED lights are supposed to give off only a fraction
of the heat that incandescent lights do but I do not recall reading what
the radiation spectrum is.  White LEDs also give off a very natural white
light, not the color shifted spectrum of an incandescent or fluorescent
lights."

LED lighting is in the early stages of development, though they have made
recent
improvements and have now, as you know, white light LED's.  LED's can be
tuned
to almost
any spectral distribution, so one can eliminate UV, etc.  The problem with
LED's is that
they don't produce much light and have to be ganged to get anything
satisfactory.  Also, there are, up to now
at least, not much in the way of lensed packages available.  I would
suggest
that you may wish to go to the
Lightfair exhibit at the Moscone Center in San Francisco this June 3,4,5.
Itis an international lighting exposition
with hundreds of dealers and manufacturers showing the latest products. I
know
that there are LED
manufacturers who will be showing the latest products, as well as a number
of
fiber optic manufacturers, etc.
I'll be there to have a look this year.  LED's are really good for very
low
level washes of light, not focused lighting.
They are very energy efficient, and can last 40,000-100,000 hours.

Larry Bowers