No Subject

[P3D <baker@xxxxxxxxxxxxxxxxx>]

>In reference to the recent letter stating the IMAX theaters probably used
>polorized glasses:

>They use LCD (liquid crystal) type shutters in a headset with a radio
>receiver built in.  This completly blanks one eye at a time.  There is not
>of the ghosting you get the polorazied glasses.  The sync signal comes in
>over the radio receiver.

I've heard that some IMAX theaters _did_ use polarized glasses (Great America
in Gurnee, IL, for "The Last Buffalo").

The IMAX theater in Chicago (showing "Wings of Courage") uses infrared-sync'd
LCD headsets with polarized material, too, for extra channel separation (did
they say about 200dB?) AND a reasonable back-up strategy for battery failures.
And, they say the shutters blink TWICE for each eye per cycle (L-L-R-R-L-L-..).
The effect is truly ghost-and-flicker-free (and this is coming from a guy who
easily notices the 50 Hz flicker of European TV :-)

Paul Baker, Naperville, IL  pebaker@xxxxxxxxxx


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