How do 3d glasses work?

How does 3D work and how come 3D glasses don't work at home?

• Brought the glasses home after seeing a 3D movie and googled "3D" images. How come it doesn't work on a regular computer monitor 3D image? I know it's a silly question but just curious :)

• Answer:

  First you need to know that a 3d movie is actually 2 complete movies on the screen at the same time. If movie 1 or movie 2 is shown by itself it would look like a complete 2d movie like all other normal 2d movies. It is just when both are on the screen at the same time many things don't line up exactly the same, so you get that double image thing with glasses off in a 3d movie. Now the job of the lenses of the 3d glasses is for the lens over your right eye to block the left eye movie but let only the right eye movie through, same for the lens over your left eye. In the theater they use polarized light. The left eye movie has one light wave, the right eye movie a different polarized light wave. Then each lens of the 3d glasses blocks the one light wave but lets the other light wave through. So each eye only sees one movie. These glasses don't have to use electricity. They work like polarized sun glasses, that block horizontal polarized light glaring off flat surfaces like water and tops of cars. For most tvs they use frame sequential 3d. The right and left eye movies flash on the screen very very fast as follows. Left, right, left, right, left, right, and so on. Then the shutters on the glasses open and close in each lens, left, right, left, right, left, and so on. So the right eye only sees it's 2d movie when the lens opens. Tvs can do polarized. All the odd number horizontal lines of pixels put out one light wave, all the even numbered lines in between those the second light wave. Then you just send each 2d movie to the correct line. I have been to theaters that use field sequential 3d. Like the imax at Navy Pier in Chicago. Those glasses used batteries. At least in the late 1990's it did, have not been there since then. I have never heard of a tv being able to do both kinds of glasses. They are only made to do one or the other, though I'm sure it is possible to make one that could, they just don't. Also you can now see why if a tv or monitor was not made to use either kind of glasses, the 3d won't work, the monitor needs the soft ware and/or hardware to do it.