How Do 3D Glasses Work

At one time or another most of us have been fascinated by some form of 3D technology. Whether it be the red-and-blue photos in magazines or a stunning IMAX 3D movie. Something about seeing flat images come to life in vibrant three-dimensionality is just amazing. But how do those red-and-blue plastic glasses work and what about those full-color movies at Disneyworld or in an IMAX theater?

The Early Forms of 3D Technology

In the late 19th and early 20th century, the stereoscope was invented. The stereoscope used lenses that merged two distinct images into one, giving the effect of a 3D scene without straining the eyes. It was a popular novelty in bars and arcades until around the 1930s, when film became the dominant media for entertainment. While we might not think about it the View-Master, a ubiquitous childhood toy for over 65 years, is a version of the stereoscope. “It is truly a phenomenon that has transcended the toy box to achieve pop culture status,” according to Chuck Scothon, senior vice president of marketing at Fisher-Price.

Red and Blue Lenses

When we hear the term “3D”, we usually don’t think of stereoscopes or View-Masters. Instead, those flimsy plasticRed and Blue 3D Glasses glasses with red and blue lenses usually come to mind. These glasses, when used with special photographs called anaglyph images, create the illusion of depth. Anaglyph images are taken using two slightly separated cameras, one with a red filter and one with a blue filter. The images are then combined to form a single picture, or anaglyph image. When viewed without 3D glasses, these images will look blurry and discolored.

Using a red and blue lens the brain is tricked into seeing a 3D image. Each eye sees a slightly different image. The eye covered by the red lens will perceive red as “white” and blue as “black,” and vice versa for the other eye. This disparity mimics what each eye would see in reality, as with most 3D technology.

State of the Art 3D

While anaglyph images prevail in print media, a new technology has eclipsed the venerable red-and-blue lenses in motion pictures. Relying on the optical phenomenon of polarization, these new 3D glasses allow for more accurate color viewing than anaglyph images.

Polarized 3D GlassesTo understand polarization, think of a garden hose. If you shake the hose up and down, you will generate vertical ‘waves’ that also move up and down. We would say this wave is vertically polarized. Similarly, shaking the hose left to right will generate waves we call horizontally polarized. Light is a wave made up of electric and magnetic fields that vary in time and, like the garden hose, it can be made to be vertically or horizontally polarized.

Like with anaglyph images, special glasses are needed to view these new 3D movies. One lens allows only vertically polarized light to pass through, while the other allows only horizontally polarized light. Two projectors show slightly different images, using light polarized in one or the other direction. In this way, each eye sees a different image,just like you would if you were viewing the scene in real life.

Because only the polarization and not the color of light is changed, polarized lenses produce much more lifelike images than their red-and-blue predecessors.

Come by Schmidt’s Optical and Hearing™ Stuart FL and feel free to talk to any of our qualified staff about any vision questions you might have, we always happy to help!

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