How Do 3D Glasses Work?

Ever wondered how you get a perception of depth while watching a movie in a theatre on a flat screen by just wearing a glass? By the way, how many of you like me haven’t returned your glasses?  Jokes aside, let's know what is the magic behind this 3D technology?

The main idea behind this technology is to fool the brain by creating a sense of depth by using some special equipment. How we do that? Just a 9th standard physics is by treating the light as an electromagnetic wave. Well, the light wave is randomly distributed and we say that the light is unpolarized. Now if we polarize the light in any one direction and take a polarizer and place it in the direction of light. All the light passes through the polarizer. But, as soon as you start tilting the polarizer the intensity of light gets on decreasing. Light is totally blocked when the polarizer is perpendicular to the direction of the light wave. This is the main idea behind the working of 3D technology.

So, the scene which you see on the theatre screen is actually two scenes offset by a certain value. This is why, when you remove your glasses, the scene looks actually blurred. So, the movie is actually projected on the screen by two different projectors one for each eye. Therefore, when we look on the screen, each eye sees only that part of the scene which is actually intended for it i.e left eye sees the left part of the scene and the right eye sees right part of the scene. How can this be possible?

The answer is the polarization of light. There are two types of polarization Linear polarization and circular polarization. The light coming from the screen to our glasses are circularly polarized. The reason of light not being linearly polarized is that the scene would have blacked out if we had tilted our head.

Therefore, one part of the screen is left circularly polarized and the other part is right circularly polarized. In the same way, one part of the glass is left polarized and the other part is right polarized. Therefore, when both the scenes hit the left glass, it only allows light from the screen which is aligned to it and cancels out the other scene and so does the right glass. This is how each part of the glass sees only that part of the scene which is actually intended for it. This separates the scene and tricks our brain into thinking that we are actually in the scene.

If we actually watch the same scene from two different angles, it creates a sense of depth which is actually the sole idea behind this 3D technology. I hope this makes sense and if not please let me know down in the comments section. Finally, thank you.