Have you seen those polarized filters that bank ATMs have so that you can only see the picture when you are facing the screen and not from an angle?
Is there such a thing that works on distance, so say you could see the picture if you were in front of the screen but not from say 2 metres away in fornt of the screen?
I personally don't think so, but am open to be proved wrong.
Well thanks for looking but that's not what I mean.
Those filters only work when you are looking at the screen from an angle. I am aware of those, but someone I know was was wanting one that blocked the screen when you are looking at it directly in front from a distance rather than at an angle.
As light travels in straight lines, I can't see how one could be possible.