I know this can hardly be considered a contribution to the thread, but: WOW!!
haha, what really got me is that caption: "The company that makes heliodisplay images says they allow a hand or finger to manipulate them. "
How in the world? So this mean you can physically manipulate the output of the projectors? I would be extremely interested in exactly how it modifies the air.
From his website:
By blowing a consistent enough stream of air, then lighting it (how? laser?) you could feasibly generate an image, with the 'air modification' being something like ionization(?), hence charged.
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