We are designing an effect in a nightclub. We want to project the
shadow/ silhouete of a dancer onto a white cloth sccreen stretched in
front of her.I'm sure you have seen this in theater and magic shows.
The ambient lighting will be very low. There are a couple of problems,
firstly there is only about two meters between the source of the light
and the screen. Secondly, the light source needs to be bright and
cool, so it will not burn the dancer. LED lighting is cool, but is it
bright enough for this. The projected shadow needs to be as sharp as
possible.

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Clarification of Question by larry70dj-ga on 31 Jul 2004 09:12 PDT

I need to know what kind of light to use, and material for the screen
to be placed in front of the dancer. The screen will be aprox 3m high
x 7m wide.

A sharp shadow requires a point source of light (or small area) so
florescent tubes won't work, but a circular florescent with a spiral
florescent in the center will be equivelent to about 200 watts
incandecent, which may be sufficient light. If not I suggest a 400
watt quartz light (only about 4 inches long) of the type used for
advertising signs. This will make a very sharp shadow, but will
produce considerable heat. If you need a bit more light than the
Quartz lamp produces, It may be practical to use an auto transformer
to raise the lamp voltage by 20% which will nearly double the light
output, but reduce the life of the bulb by about ten times.

Sorry you did not get an answer. You may wish to cancel and ask again
in slightly different words. Leading edge LED have about the same
efficiency as the spiral florescent, but I believe they are more
expensive, and less available. 150 watt equivelent spirals are now
available that use about 30 watts each, so 7 of them mounted as close
as possible would produce the equivelent of 1050 watts, perhaps as
much light as two 400 watt quartz lights, but only about 1/4 the heat,
and the shadow would be almost as sharp.   Neil