# How do 3D glasses work? - R

3D Glasses…How They Work
Lacey M.
2012
3D glasses transform an ordinary movie theater into a three dimensional adrenaline rush. 3D is all about the glasses and how they trick your eyes into seeing certain things. In this experience the objects on the screen will feel like they are coming right at you. It will knock your socks off. Now let’s go behind the scenes and unlock the mystery behind those multicolored glasses and see why they are so important in seeing a 3D film.

Projectors and Screen
Two of the many things to make 3-D glasses work are the projectors and the screen. If you go to a three dimensional movie the projectors display two slightly different images that bounce off the screen into the glasses. The film is recorded by two different cameras that have slightly different views. When the movie is played in the theater, it is also shown on two different projectors. One of the projectors always shows that angle of images in a reddish color while the other is in a slightly bluish tint (or sometimes greenish). For the images to get to the glasses they have to bounce the light off the screen into the glasses. Without these two essential items the 3-D glasses themselves wouldn’t work.

 Figure 1 Diagram of Projectors, 3D Glasses, and the Human Eye

3-D Glasses
There are many parts that contribute to making an enjoyable 3-D film, but the most important and most popular
 Figure 2 3D Image of 3D Glasses

item are the 3-D glasses. 3-D glasses have one red lens and one blue or green lens made out of cellophane. This takes the light that was uses the film to appear as if it is in 3-D. It reflectes off the screen into the lenses and separates the red light so it goes through the blue or green lens and the blue or green light goes through the red lens. The light separates so that one image will go through one eye and the other image through the other. This is how binoculars work. The two different colors that are projected from the cameras correspond with the colors in the lenses is to give the illusion of depth perception. This causes the film to appear as if it is in 3D.

Eyes and Brain
The human eyes are fascinating with the sense of sight. They are about two inches apart (5 cm), so you see the world out of one eye slightly different than out of the other. You use binocular vision to tell the distance of things that are far away. When you look at an object you see the light reflecting off of it through your eye and into your retina. In the retina the light transforms into nerve impulses that travel to your brain, glands, and muscles. This helps you see how far away things are. If you were to close one eye you would still be able to see distance, but it wouldn’t be as accurate as with both of your eyes. You would have to find clues and relate objects to other objects to get as close as possible to the correct distance. Your brain takes the two images from both of your eyes and correlates the two images. The brain takes the two images produced and finds an object that is in both images that your brain can correlate. If the object that you’re deciphering is far apart in the two images then it is closer to you, but if the object in the scenes are closer together then the object is farther away. This is how 3D glasses trick your brain by forcing you to see the images farther apart. The human eyes are unique and interesting features of the human body.

The next time you pay the extra money to enjoy a spectacular 3D experience, be sure to pay attention to all of the pieces of this puzzle. Take a good look at the funny glasses with different color lenses. Try to find the different projectors. Close one eye to see what the difference is between the two eyes. Then sit back and enjoy!

Glossary
Adrenaline: A hormone that is produced during exciting events.
Binocular vision: Vision that you see simultaneously with two eyes.
Cellophane: Thin, transparent sheets of paper that is mainly used for packaging.
Correlate: To see similarities in two things.
Retina: The innermost part of the eyeball that receives the image that is produced by the lens.

Citation

American Paper Optics LLC. “How Do 3D Glasses Work.” American Paper OpticsLLC. American Paper Optics, 2012. Web. 19 September 2012.

Brain, Marshall. More How Stuff Works. New York: Wiley Pub, 2003. Print.

“eye.” Compton’s by Britannica. Encyclopedia Britannica Online School Edition. Encyclopedia Britannica, Inc., 2012. Web. 24 Sept. 2012.

Walker, Jearl. The Flying Circus of Physics. New York: New York John Wiley and Sons, 1977. Print.