Quote:
Originally Posted by Titan1a
Fresnel lens. Used to magnify the picture.
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Yes, a Fresnel lens. But since magnification/projection is done by the mirror optics, part of this Fresnel's purpose is to direct the light out to the viewers (preventing the effect of looking down a tunnel where only one viewing position is good, or only part of the picture can be seen from any position). It controls the spread of the light such that multiple viewers can see it, yet it is not spread over a whole hemisphere to extreme angles where no viewers would be located.
I don't know how many layers the screen has and how much general diffusion is there in addition to the Fresnel. It would be interesting to check. Can you try looking at the picture from extreme right and left and extreme high and low, and see how far the viewing angle goes?