Hello,

I've noticed a few threads discussing 20" 1600x1200 LCDs, and since no one has ever actually built one, I thought perhaps a thread discussing theory would be interesting. Once I get a job later in the year (new graduate), I will have some disposible income to build it, but for now, I will just plan/dream.


So anyway, the BenQ FP 2091 has a display area of 16" x 12", which translates to 406.4 x 304.8 mm. So theoretically, the Pro lense fresnals (431 X 406 X 2mm) will accomodate this screen.


What I would like to know is how to calculate the focal lengths and such so that I have a basis to start and get an idea of the size of the box, distance between light and collimator and LCD to triplet, etc..

I can't imagine going much higher than this screen size for DIY so we might as well start the research now so we have 15", 17" and 20" Lumenlab projector designs ready.

Janosek

the distances between lenses are based on the FL of the various lenses and not the size of the lcd. Since the pro fresnels (which you'll need for a 20" panel) are large enough for your lcd panel you should be okay. Just use the distances for a 17 inch plan as the optics should be the same. There are various versions posted here and there, folded and straight, etc... As for the dimensions of your box, it looks like you might need to keep the fresnels uncut, or cut them just slightly. Since they're the biggest items in the box, you can get your height and width dimensions based on them. Your length will come from the FLs of the lenses and whether or not you opt for a straight design or folded one. Good luck, sounds like a good project.