I am putting together a LED Projector powered by a Pi for fun, but want to get as much quality out of it as possible, and while I have been doing a LOT of reading I still have a few questions that I would like to try to get answers to before I start the build. I have tried some other forums and nobody has been able to answer these yet.
I am using a 7" 1024x800 innolux display, which cam with the PCB800099 display driver, which is pretty standard for all 5 & 7" Pi displays. I have a 6,000 Lumen 50W Chip LED, heat sink, driver, and a 44mm consolidator with 55mm reflector. I have 2 optical grade pvc fresnal lenses that I do not know the focal length of, they were sold as page magnifiers, but are not the thin flimsy ones, and I have a 5 inch f:3.5 100mm - 150mm zoom lens for a kodak Ektographic slide projector.
Anyways, this is my BIG question, will this stuff work? Specifically, I am worried about the projection lens, as I read a few times that you can't use an LCD screen larger than 2" with a slide projector lens, but in all the calculators I have found, all the numbers for size, viewing angle, corner brightness, and etc are all perfect, except the screen is a LOT bigger than I wanted, as I was hoping to fit it into an area of the wall with a backset, but I can change that. I had ordered the lens when I first started designing this, and saw "slide projector lens".
The next question, can I have both fresnels be the same focal length? I see a lot of people off-set them, like 220mm for the front and 230mm for the back, I dont know if that is because they both have to be at focuk length from the projection lens, or if it is because those are standard sizes that come with an overhead projector, which I can get if the stuff I have will not work.
FInal question, is in regards to the LCD backlight, which has diffusers and etc, can I use any of those? Like the LCD I am using has one clear piece with a bunch of little dots meant to soften and equalize the light, can I keep that on the back, or is that a bad idea?
Any problems you guys see?
This is the calculator I used:
http://www.tronixbee.com/projcalc/
Oh, I am looking for a free Ray Tracing / Optical design suite, like ZeMaz opticstudio or LightTools, where I can lay out the projector lenses, and get a visual of how the final image looks, so that I can play with a few designs without wasting cash. Opticstudio and lighttools are both way too expensive.