Polarized 3D Glasses - How do they work?
By means of restricting the amount of light to hit each eye it is possible for polarized 3d glasses to create the illusion that three dimensional images are present. A stereoscopic film actually consists of two images projected at the same time onto the same area through polarizing filters oriented at right angles to each other. The viewer wears low-cost eyeglasses which also contain a pair of orthogonal polarizing filters. Since each filter will only admit light that is similar in polarization while also blocking the perpendicular polarized light, each of the eyes will see only one of the images, thus creating the said effect.
3D Glasses

Polarized light rays bouncing off a cinema screen often get diffused and this de-polarization can be problematic. Using so-called silver screen– actually coated in aluminum– will solve the problem. A comparatively low cost can be achieved by means of a pair of aligned DLP projectors and accessories. A computer with a dual-headed graphics card is necessary. (in 2003, less than $10,000 US) system for displaying stereoscopic 3d data simultaneously to tens of people wearing polarized glasses. Such a system, called a GeoWall, has been used for several years now in the Earth Sciences thanks to the GeoWall Consortium, with several open source and commercial packages available.

3D Glasses
The most practical method of showing 3D images to just one person is a device called an image combiner, which involves two perpindicular screens and a system of partly-aluminized mirrors. While one image is viewed through the precisely angled mirror, the other is merely a reflection. Correctly adjusted glasses are equipped and filters, properly polarized, are attached to the image screens. There is another, similar system that projects on one screen with the topmost image inverted and viewed in a partly reflective horizontal surface and the lower image shown right-side up. Cathode ray screens are best suited to polarizing glasses, since LCD screens contain polarizers to control the presentation of pixels, and the polarization can conflict.
In 2003 Keigo Iizuka discovered an inexpensive implementation of this principle on laptop computer displays using cellophane sheets
Polarized stereoscopic pictures have been around since 1936, when Edwin H. Land first applied it to motion pictures. The so called “3-D movie craze” in the years 1952 through 1955 was almost entirely offered in theaters using polarizing projection and glasses. Only a minute amount of the total 3D films shown in the period used the anaglyph color filter method. IMAX 70mm film projectors are a new innovation and as such highly reliable. An entirely new breed of polarized 3D animation movies are finding niche in classy theaters. It is somewhat difficult to apply the process of polarization to home 3-D or DVD presentations. At this point only anaglyph glasses may be used to view the new HD shows and are beginning to be aired occasionally by NBC and the Discovery Channel.
Polarized 3D Glasses

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