Hi Brent,
I have working with projectors during many years. In three panels LCD with normal "white" lamp there is both a splitter and combiner. But there is some problem, the intensity from the lamp is very intensive, the filter will not last for long time. Especially the IR cut filter. The other problems, many models have very small filters, I don't think they can be used for a APS-C sensor, but I shall take a look if I find an used LCD projector.
Very long time ago in the early 1980 there was a very special CRT Elctrohome ECP projector that had a combiner of very big size, I think it was 5", but that's way to big. It also have a big f/1 lens, but poor quality compare to the need in astronomy photos, but if you find one, take the spare parts from it and do something fun.
http://www.hcinema.de/pro/anzeigen.p...omeecpgraphics
Thank Brent for the idea/information, I shall add this information on the homepage. It's much easier to find a used LCD projetor then old video cameras with this construction.
/Lars