Re: Xenon bulbs / U.S. spec lights

["faust" <faust@gateway.net>]

> 
> If this helps anybody understand this...  we have similar lights
> (mercury vapor maybe) in our barn...  They don't have bulbs, and take
> about 5 minutes to get warmed up to the point where they do any good. 
> They also appear slightly bluish...  I think some streetlights are this
> way also...   and what about flourescents?  Same principle, right?

Mercury vapors produce light by flourescence I believe, as opposed to
incancdescence (halogen H4s), or arc/discharge(HIDs).  Streetlights are
usually sodium arcs which would be a similar principle.  In theatre, we use
several arc/discharge sources for things like followspots, etc.

I'm not real familiar with the HID headlight system, but I'm willing to bet
that it's not the gas in the lamp that makes the difference.  Its the
actual source of the light.  So, a company could  fill the envelopes of
lamps with xenon and market them as "xenon" lights, when in reality, they
are not much different than a regular bromide(halogen) filled lamp.  Arc
sources usually have a much higher color temperature than incandescent
ones.  

Do HID system have a built-in cooling system, fan, heat sink, etc.  Just
curious.

Later,
Greg Faust

Technical Director
Performing Arts Dept.
Buffalo State College
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