Adrian C wrote:
Martin Angove wrote:

Have you ever *seen* the light from a discharge lamp? Ignoring the
problem of UV exposure (they produce gallons of the stuff) they have to
be the brightest source I've seen, Watt for Watt.

Hwyl!

M.

Just thinking. Do white LED's yet come anywhere close (even in an array?)


Perhaps.
But.
IIRC, the luxeon 1W chips are about 1.5mm^2.
That's about .2W power, when you compare it to a discharge bulb, as
it's much less efficient.

1.5mm*1.5mm means you get about 36/cm^2, or 8W equivalent.
Some new 'vapourware' LEDs claim about 3 times that, or 24W/cm^2, but
that means a source size of over 3cm diameter to hit 240W.
And if you're doing it at all, you probably don't want to use white
LEDs, but work out some way to do it with RGB ones, and eliminate the
insanity of wasting 2/3 of the light on a filter wheel.
And the other problem I glossed over is that LEDs need kept well under 100C
to function.
The discharge bulb will be quite happy at a wall temp of 300C.
And, with the better part of a kilowatt going into an area smaller than
the contact patches of some CPUs, thermal design is going to be a real
bitch.