This material is taken from this site. It is rather dated, at around 8 years old now, but is the most relevant information I have found so far in regards to Stereo Projection of Polarized images.

http://www.stereo3dgallery.net/Pages/3DGuidebook/ViewingMethods_Projection.shtm

The below is ALL © 2003, John Hart. All rights reserved.

Projectors with other polarizations may not work.  For example, if R is +45, B is -45 and G is vertical.  Then one eye sees all B and 1/2 power G, etc.  The best way to test is to set the projector on pure white, and hold the polarizer over the lens at 45 degrees.  Do you still get pure white, though at about 1/3 the power  (Note 1/2 is lost by geometry, and some more is lost because the polarizing material is not perfectly clear)?    

DLP projectors generally produce a randomly polarized output beam.  Thus placing a polarizer at any angle over the lens will not induce a color shift.  However, to be safe, you should always test before buying.  DLP projectors use a micro-mirror device to produce the image.  Since light projected off a mirror tends to preserve polarization, randomly polarized light from a metal halide or xenon lamp retains this state of polarization after reflection.  It also passes through a color wheel and lenses that usually will not affect the polarity of the beam.  Placing a polarizer in front of the lens will produce a beam polarized at the angle of the polarizer.  There is a factor of two loss in beam power (plus a little more for the polarizing material absoption), because for each moment the random beam is lined up with the polarizer, there is another moment that it is perpendicular (or crossed out).

Note:  Three chip DLP projectors use beamsplitters instead of a color wheel.  While the color is better, unlike mirrors, beamsplitters do polarize light.  Test required.

I have not yet had the opportunity to extensively test light-amplifier projectors (DILA).  These uses a hybrid system that always has beamsplitters.  The JVC  DLA G15U (Dukane 9015) did not work with an over-the-lens polarizer

In summary,  digital projection has the great advantages of flatness of field, high brightness, non-destructive projection, setup ease (no reels), and digital (vs. tedious mechanical) stereo registration.  Digital images will not approach those from film projection until much higher resolution and contrast, approaching 1600 x 1200 and 1000:1, respectively, are available.  However, recall that the human eye can only resolve a certain level of detail (about 2000 line pairs across a 6 foot screen 6 feet away).  As people sit further back, the required resolution, to totally meet that of the human eye, falls off linearly.  If everyone is 3 or more screen widths back, for example, a 1280 x 1024 projector is just about "perfect".

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