In South Korea, a team of investigators thinks they have a way to show 3-D movies without glasses in commercial theaters.
3-D
televisions are available now, and consumer electronics companies have
been showing off some glasses-free technologies (as on the Nintendo
3DS). But generally, theaters use a two-projector polarized light
system.
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Each projector displays an image, but the images are offset slightly. The
projectors, meanwhile, are sending out light that is polarized. That
means that at certain angles half the light is absorbed.
It's possible
to see this effect with sunglasses; two polarized lenses. Put one in
front of the other and start rotating it, and it's not possible to see
through them when one is perpendicular to the other. In movie theaters,
the 3-D glasses are polarized so that each eye only picks up one image
at a time, giving the illusion of depth. Two projectors, though, can be
cumbersome and expensive.
There
are single projection methods, but those require even more moving
parts, involving physical barriers akin to venetian blinds between the
screen and the viewer. Called the parallax barrier method, the barriers
limit which image the eye sees, creating a 3-D illusion.
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To
fix this, the South Korean team, led by Byoungho Lee, professor at the
School of Electrical Engineering at Seoul National University, used
polarizers to stop the passage of light after it reflects off the screen
rather than doing so at the projector.
The polarizer is a coating
called called quarter-wave retarding film. It acts like the polarizers
in two-projector systems, except instead of relying on two images, it
splits up the single one coming off the screen to the eye. Basically, it
moves the 3-D glasses to the screen, so the audience no longer has to
wear them.
It
will be a while before theaters use this, but it's been shown to work
in at least two types of displays, and offers a path to cutting the
costs (and the admission prices) of 3D movies.
