How does 3Dimensional glasses work?

Answer 1

There are two types of 3-D glasses:

1) Different colored lenses. An image containing both colors is projected at your face, but the tint of each lens filters out one of the colors (the red lens prevents you from seeing the red image, while the blue lens prevents you from seeing the blue image), resulting in each eye seeing a slightly different image. This difference is the basis for depth perception and binocular vision. Your brain combines the two images, fooling itself into thinking the images have depth.

2) Polarization. If you have ever had polarized sunglasses, you know the effect. Imagine the polarized lens as a picket fence and light waves as pieces of wood that fit between the slats. The only wood pieces (light photons) that make it through the fence (the lens) are the ones oriented in the same direction as the slats in the fence. All other wood pieces (light waves) are filtered out. In this method, the two images are pre-polarized by a filter on the projector, which results each image consisting of only one wave form (it's convenient to thing of these wave forms as vertical and horizontal). On the glasses themselves, one lens is polarized vertically and the other horizontally, so the only the vertically polarized image goes through the vertical lens, and only the horizontally polarized image goes through the horizontal lens, again resulting in your brain seeing a slightly different image in each eye, which causes the illusion of depth.