BACKGROUND OF 3D In 1893, William Friese-Green created the first anaglyphic 3D motion picture by using a camera with two lenses. During this time, the first lenses on 3D glasses were typically red and green. Popularity of 3D motion pictures was reborn in 1950 and continued to improve over the next couple of decades. By the 1970s, the lenses were improved to red and cyan for slightly better quality. Today, 3D pictures are used in movie theaters and television. To understand how 3D glasses work, we first must understand binocular vision— being able to see in three dimensions. BINOCULAR VISION Having two eyes allows humans to tell how far away an object is. This is known as depth perception. Our eyes are about two inches apart, therefore each eye sees the world from a slightly different perspective. When the two different images come into the brain, the brain calculates the distance between each image. The brain combines the images and distances and allows you to see one 3D image. VIEW-MASTER The View-Master is a great example of how binocular vision works. Each image is photographed from a slightly different position, so each eye is given a slightly different image. Each eye sees only one image, but the brain combines the pictures to form one 3D image. HOW DO 3D GLASSES WORK? 3D glasses are actually simple. They work in a similar way to View-Masters. Each lens, no matter which type of 3D glasses they are in, feed a different angle of the image into each eye. The screen or projector displays two images. Each image is fed into the corresponding lens and into the eye. There are three common types of 3D glasses: 1. Anaglyph 3D glasses 2. Active Shutter 3D glasses 3. Polarized 3D glasses ANAGLYPH 3D GLASSES Anaglyph glasses were the first type of 3D glasses created. These glasses either have one red and one green lens OR one red and one cyan lens. Two images are displayed on the screen, one in red and one in green/cyan. Each lens filters only one image through to enter each eye. Your brain does the rest: the images are combined and appear three-dimensional. These glasses are cheap, however, the quality of the 3D image is low. Today, they are typically used for movies watched at home. ACTIVE SHUTTER 3D GLASSES Active Shutter glasses are much more complex than Anaglyph glasses and have great 3D quality. There is an on/off button and they must be charged. They are typically used in home theaters. Each lens has liquid crystal that darkens when signaled by the screen. For example, the left lens may be signaled to turn black or darken while the right lens allows the image intended for the right eye to enter. The screen typically communicates with the glasses through an infrared emitter or a radio frequency emitter. POLARIZED 3D GLASSES Polarized glasses are used in many theaters today, including Disney World’s Universal Studios. Each lens has a different polarized filter that corresponds with one of the images on the screen. The images are projected by two synchronized projectors. The angles at which each lens is polarized restrict the amount of light passing through, allowing only one image to enter each eye. The brain combines both images to create the 3D effect. If you look at Woody’s legs, you can see two different images projected onto the screen. While wearing the glasses, Woody will appear 3dimensional. POLARIZED GLASSES You can see that the left lens will only allow the vertical component of the light to pass through. There are two types of polarized glasses: linear and circular. 1. Linear glasses do not allow the viewers to tilt their heads; if they do, they will lose some of the 3D effect. Tilting of the head will tilt the filters, causing parts each image to bleed over into the other filter. 2. Circular glasses allow the viewers to tilt their heads without losing any 3D effect. The filters are circularly polarized in opposite directions. These are used more commonly today. HOW THIS RELATES TO PHYSICS Studying 3D glasses relates directly to the Polarization and Interference Lecture (Monday 4/14). We learned that non-polarized light vibrates in all directions. Certain materials can polarize a ray of light, only allowing compatible components of the light to pass through. For example, when light enters a vertical medium, only the vertical component passes through, minimizing the amount of light seen. This is how polarized 3D glasses work: the lenses of the glasses are angled differently from each other as well as one of the images presented on the screen, only allowing compatible rays of light to pass through each lens. This allows different images to enter each lens to produce the 3D effect. NEW INSIGHT PROVIDED While creating this project, I have learned that there are more than one kind of 3D glasses. I learned that Anaglyph glasses work differently from Polarized glasses. Anaglyph glasses have different colors entering each lens, while Polarized glasses have different angles of polarization that only allow matching light rays to enter each lens. The real life application of polarized light to 3D glasses bettered my understanding of how light polarization works. Most importantly, I now understand why there are two images on the screen or why the images on the movie screen look fuzzy when I take off my glasses at the movie theater. WORKS CITED Bnext3D. "How Do 3D Glasses Work - Difference between Types of 3D Glasses." YouTube. YouTube, 25 Feb. 2013. Web. 18 Apr. 2014. Brain, Marshall. "How 3-D Glasses Work." HowStuffWorks. HowStuffWorks.com, 18 July 2003. Web. 18 Apr. 2014. "How Do 3D Glasses Work?" 3D Glasses. American Paper Optics LLC, 2010. Web. 17 Apr. 2014. Klein, Alexander. "Stereoscopy.com - FAQ." Stereoscopy.com - FAQ. Stereoscopy.com, 2014. Web. 18 Apr. 2014. Nauman, William. "History of 3D Glasses." EHow. Demand Media, 07 May 2009. Web. 18 Apr. 2014.