In a comment on my earlier post about 3D movies, Phillip Helbig writes
In the latest Physik Journal (magazine of the German Physical Society), there was a two-page article on 3-D techniques. You mentioned three: colour, linear polarisation and the quarter-wave-plate model (your hypothesis was correct; that's how it works). The last is definitely the best of these three, but shares this problem with linear polarisation: the reflected image has to be polarised, so the screen has to be mirror-like, not just a white screen.
It’s nice to know that that’s what’s really going on!
Phillip goes on to say
There are two other techniques. One projects frames at twice the normal rate, altenately for each eye, and the glasses contain infrared-controlled LCD shutters which alternate at the appropriate rate. Probably the best system, but the glasses are more expensive.
I actually used a system that worked on this principle, way back in the 1980s, when I had a summer job working in Don Wiley‘s lab at Harvard. It was a special computer with a huge monitor that rapidly switched between two images, along with a pair of glasses that plugged into the computer and alternately switched from opaque to transparent so that each eye was presented with one of the images. This must have been a special-purpose, very expensive system back then. I don’t remember how fast the switching was; I’m sure it wasn’t fast enough to show movies and have it look good. The lab used it to visualize big biological macromolecules.
Another one is quite interesting: for one eye, use three primary colours, and for the other eye, use three OTHER primary colours. The filter for each eye only lets through the primary colours intended for that eye. (For a given perceived colour, there are many ways of mixing it out of narrow-band "primary" colours".
I’ve never heard of this. What a cool idea. The next time I teach our mathematical methods class, I’ll use it as an example of vector spaces and projection operators:
The spectrum of a light source is a vector in an infinite-dimensional vector space, but we only see color in a three-dimensional space. Your visual system is in effect projecting from the big space down to the small space, so of course there are many different spectral shapes that are perceived as the same color. The filters in front of each eye are additional projection operators. By a clever choice of those operators, you can use different parts of the original, big vector space for each eye, and still present the entire three-dimensional space to each eye.
I bet you can mock up a not-very-many-dimensional model of how all this works.