I'm wondering if anyone has some insight to offer on the idea of building a remote light engine that pumps a larger percentage of the light from the MH bulb into an optical fiber, which would run to the box and then some optics to make it a point source for the rear fresnel.

I'm already planning to recess my ballast into the ceiling (doing a ceiling-mount PJ), but if I could move that whole big bulb out of the enclosure, I could maybe make it considerably smaller.

I have doubts about the effectiveness & practicalities of doing this, but in the past I have worked on big surgical microscopes that used a very bright zenon light source pumped into fiber to light the field of view, so I know it's possible in principle, even if it's not practical for our application.


Any thoughts or info much appreciated,
Phil.

i don't think this would decrease the size much, as the rear fresnel still has a focal point of 220mm, requieing the light to come from that far away.


Xenon

From the way I see it, a microscope only has to have a very small area illuminated, so it would be quite hard to make the light spread back out and meet with the required fresnel lens optics without a few lenses in there, which is going to take more space and probably not gain you anything. Plus there is light loss through fiber lines, which is why fiber optic equipment like T1 lines have a limited distance that they can be ran before having to be "re-fired" I guess you could call it. Not that that would be a problem, but the light loss would be.

It is possible in principle though, you would just have to figure the light distribution coming out of the end of the fiber line and throw a lens or two in there to get it to the fresnel correctly.

Thinking about this further, I'm thinking it would be very difficult to have an efficient coupling from a light source the size of what you get with that 3/4" arc length.

As for decreasing the box size, I was thinking that with such a remote light engine setup, all of the rear optics would be different, so the 220mm number could be reduced.

Thanks,
Phil.

I don't know how the light coming out of the end of a fibre line is distributed, you would have to do some experiments, but you might be able to do away with the rear fresnel and set up an almost LED-array type system. You would have multiple fibre lines being fed and then try to divide the light evenly across the LCD. The good thing here is you would also not need IR or tempered glass protection. You could still use the rear fresnel to focust the light into the fiber lines, but like you said the coupling would be hard to figure, plus coming up with all that fibre optic cable (freaking expensive retail, could probably get some used for free if you knew a guy who knew a guy).