With 3D movie being the latest craze in entertainment many people are interested in understanding how 3D movies work. To understand this you need to have a basic understanding of how your eyes process what they see and allow you to see in 3 dimensions. When you look at an object your left and right eye see slightly different perspectives of the same object. Your left eye will see more of the left side of the object and your right eye will see more of the right side of the object. This information is then combined by your brain to allow you to see the object in 3D. The same principle is used to create 3D movies.
3D movies are shot by using two cameras right next to one another. The left one captures slightly more of the left side and the right camera captures slightly more of the right side. These two images are then projected at the same time to produce a 3D image. Old 3D movies used to use blue and red light to create the 3D effect. This is still used in producing 3D pictures in books. Footage for the left eye would be shot using a red lens filter and footage for the right eye would be recorded using a blue lens filter. The two images would then be projected on top of one another on the movie screen. The viewer would wear special blue and red glasses that would screen the light so that the left eye would only see red light and the right eye would only see the blue light. This would allow the image to appear as 3D. However, this limited the colors that film makers could use. Modern 3D films now use polarized light instead.
The use of polarized light is very similar to using red and blue light. As with old 3D movies new 3D movies are also recorded using two lenses side by side. The difference is that each camera has a different polarized lens. Polarized lenses only allow light to reflect off one surface. If you have ever worn polarized sunglasses you would have been exposed to this. When you look directly at an object it appears lighter, but if you tilt your head the image becomes darker. When recording a 3D movie the image that is meant for the left eye is recorded through a polarized lens with tiny parallel horizontal lines. The image meant for the right eye is recorded through a polarized lens with tiny parallel vertical lines. The glasses you wear to watch a 3D movie has the same polarized glass and separates out the images so that your brain can combine them and allow you to believe you are seeing a 3D object.