how do 3D movies work, and why are the glasses 2 colors?
In: Technology
3D movies (and books) work by having two layers of information encoded on the screen/page. You then wear a special pair of glasses that filters out one layer so that your left eye only receives on layer of information and your right eye receives a different layer. This is basically how your eyes work in real life since they are spaced out from each other (they each have a different point of view of the world). By mimicking how your eyes work in real life, you can create the illusion of three dimensions.
Early on, it was common to do this with colors. You would have a layer with one image in red and another layer with one image in blue. You would then have glasses with a red lens (which filters out the red layer) and a blue lens (which filters out the blue layer).
Today, we work with light of different polarization. Light that hits your eyes can be though of as a wave. Think about if you and a friend took a jump rope and one of you wave your arm up and down making the rope undulate, creating a wave starting from your end and moving toward your friend. You can do this in an up-and-down fashion, or a left-to-right fashion, or any orientation in between. We call this orientation *polarization.* Light waves behave in this same fashion and individual waves will be oriented randomly.
We can create filters which will block light waves that are oriented in a certain way. This is how sunglasses work. For a 3D movie, we can create an image with two layers of information and each layer only uses light of a given orientation. Imagine one layer only uses light oriented up/down and the second layer only uses light oriented left/right. Then your will have one lens which blocks on type of polarization and another lens that blocks the other. The result is the same with the red/blue strategy above, but now you can do it using any color and create a more realistic image.
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