Talk:Multitouch screen

I think you will actually need a convex mirror for this setup. A concave mirror will only require MORE distance to get the image to the right size since the rays have to converge and then rediverge. Try tracing several rays from the projector to the screen using the mirror and an estimated reflection angle. With a concave mirror, there will be a point after the reflection where all the rays converge where with the convex mirror, they will never converge. The only way a concave mirror will work is if it has a REALLY small focal length. -Kinsey