3D Technology creates the illusion of deep by recreating the same kind of stereoscopic vision we have outside the theater. Each of our eyes observes the same thing, but because they are a small distance apart they see that thing from just a slightly different angle, or perspective. Our brains they put the imagery together, allowing us to perceive depth, the third dimension.
The 3D technology must to rely on glasses or some other convenient prosthetic to achieve what our eyes and brain do naturally. This can be accomplished by the way each lens blocks the imagery meant for the other eye while permitting the image meant for that eye to pass through. There are two basics ways to do this, each one of which has spawned many permutations.
The most familiar is timed passive or polarized 3D. The passive lenses are in the old bicolored 3D glasses which originated in the middle decades of the 20th century, one lens red and the other green or cyan. Called color anaglyph glasses, they were typically framed in cardboard and relied on color filtering to allow each eye to see one of two images that were projected simultaneously upon the screen. Viewing the screen through colored lenses played havoc with color fidelity, causing many viewers to complain about visually unpleasant and uncomfortable viewing experience.
The newest passive 3D glasses with polarized lenses rely on separating the two imagines via polarization of light, rather than filtering color.
Light polarized at one end of the spectrum cant’ pass through lenses made to admit the light from the opposite end of the spectrum, thus two lenses with different polarizations can deliver two separate images to the eye, recreating the dimension of deep. This technology isn’t compatible with most home theater systems which use DLP, LCD or plasma displays as it relies on front projection system.