What you can use for rear screen projection?

Answer 1

Rear projection screens are difficult to make. They have to achieve two things in order to work: First, they need to pass light freely. As the projector is behind the screen, the audience in front of it would see nothing if the screen failed to pass light from one side to another. Secondly, they have to prevent light passing straight through or no image would be seen, just the light from the projection lens. The two requirements are in conflict with each other. The more that light is captured by the screen and then dispersed, the less is actually delivered to the viewer. The more that light passes freely through the screen, the more obvious the light source becomes. Screen manufacturers spend a great deal of time and money to produce either rigid or flexible surfaces that meet both requirements and result in an evenly illuminated image. Homegrown equivalents are hard to produce but there are two ways that may produce results. In past times, glass was ground on one side to produce a frosted surface. Glass producers can still carry out the process but the cost is likely to be even higher than purpose made screens. The other option is remarkably low cost. Translucent paper such as tracing paper, baking paper, greaseproof paper etc can be used for small screens. Held flat in a frame, these papers can produce a fairly respectable image. Most certainly, they are not equivalent to a good projection screen, but for cost, they are unbeatable. Finally, stage effects sometimes use a gauze as a screen. The open weave makes them semi transparent and they can be used as a form of rear projection screen. They only work from a distance so for normal rear projection applications they won't be very effective. Treat all of the ideas as experiments and have fun with them.