Science & Tech

How do 3D glasses work

By Susan Crowley
Info Guru,

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girls wearing 3D glasses
Did you know each eye has a slightly different view of everything you see?
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Have you ever wondered how those large dark 3D glasses that you're given at special events at movie theaters could make a flat screen bloom with three-dimensional images? Because the centers of our two eyes are spaced a few inches apart, the brain interprets the two different images it receives from each eye by overlaying them into one view. This gives us the ability to see in three dimensions even when the image presented is flat

The development of the Polarized three-dimensional system of filming by American inventor Edwin Herbert Land made color 3-D movies a reality. Films made using this method are shot with two cameras or a special camera with two lenses. In the theater, the two films are projected simultaneously. A polarizing filter in front of the left projector lens orients random light waves into one plane, while a different filter in front of the right projector lens orients light waves into a perpendicular plane .

Filmgoers wear glasses with gray polarizing lenses that orient light waves in the same way as the filters on the projectors. This causes the viewer's left eye to see only the image from the left projector and the viewer's right eye to see only the image from the right projector. The brain receives these two separate images and fuses them into one 3-D image.

Movie projectors creating these special effects are actually showing two different images, so it makes little sense visually if you watch without your 3D glasses. When you don your 3D glasses, however, you'll see in three dimensions. This is because each lens is specially equipped with light or color filters to block certain aspects of images from entering one eye, while allowing those same aspects to be seen by the other eye.

The specially crafted lenses of the 3D glasses "trick" the brain into correlating two different images into one, creating a three-dimensional image that is nothing but an illusion.

The first polarized film was demonstrated in 1939 at the New York World's Fair. In the 1950s, attendance at polarized 3-D movies soared. Between 1952 and 1955, over 110 features, shorts, and cartoons were produced in 3-D. These included the classics House of Wax (1953), It Came From Outer Space (1953), Kiss Me, Kate (1953), Hondo (1953), Creature from the Black Lagoon (1954), and Revenge of the Creature (1955). The 1950s also marked a high point for 3-D still images. In addition to films, 3-D images appeared in comic books, newspapers and magazines, posters, jigsaw puzzles, and greeting cards. The polarized film process lives on in today's state-of-the-art 3-D movies in theme parks, as well as some IMAX 3-D theaters. IMAX 3-D movies project giant images on screens seven stories tall, giving viewers the impression that they are submersed in the scenes projected on the screen.

Similar technologies now are being incorporated into computer games, some of which require 3D glasses for a full three-dimensional gaming experience.

If you've saved those red and blue glasses you once wore to watch campy 3D movies, don't throw them out; they may have life in them yet, as new technologies are now being developed and tested to transform the flat virtual world of the Web into a three-dimensional one. If you enjoyed this article and found it helpful, be sure to read other informational articles that will satisfy your curiosity.

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