How Do 3D Movie Glasses Work?

If you have watched a 3D movie, you will have to wear special 3D viewing glasses. But, how do they work? In order for movies to appear in 3D, you must wear polarized, or 3D, glasses. Polarized means that the glasses filter the light based on how they are traveling. Light typically moves in a spiral, moving both vertically (up and down) and horizontally (side to side). One of your lenses only shows you the light that moves up and down, while the other lens only shows light that moves from side to side. This optical illusion tricks your eyes into believing that the objects that you see on the screen are in 3D!