How do the 3D glasses work?

3D glasses are a staple in most cinemas around the world and are most commonly used for all the intense, packed with special effects movies that benefit so much from allowing you to see the image in 3D. However, not many people realise how they actually work and why is it possible to see an image, projected on a flat screen as a realistic 3D projection that seems to be coming out of the screen. The idea is simpler than one could think and it’s all thanks to stereoscopy – a way of projecting two different images at the same time and allowing them to reach your eyes in a slightly different way thanks to your 3D glasses. How do they actually work?

How do you see things in 3D glasses

Remember those cheap, paper 3D glasses that had one lens coloured red and the other blue or green? This technique, although not widely used now because of its lower quality, is the best way of describing how 3D glasses work in general. A 3D movie viewed without glasses is a very strange sight and may appear to be out of focus and fuzzy. This is because the same scene is projected simultaneously from two different angles in two different colours, red and cyan (or blue or green).

3D glasses with coloured filters on the lenses separate the two different images so each image only enters one eye. This way, your left eye sees a different picture than the right eye, which leaves your brain to connect those two images together into one and view it as 3D. This might seem not very natural, but in fact this is how human eyes work either way, with real objects around us. When our eyes pick up different reflections from surfaces of the same object, it creates depth that the brain sees as an actual 3D object.

New technologies

There have been many advancements in the 3D technology and now the coloured lenses are a thing of the past. The method that is now preferred by the vast majority uses polarized lenses, as they allow for a deeper, better quality viewing. A digital projector allows to show two separate images, each with a different polarization. The glasses allow only one of the images into each eye, because they contain lenses with different polarization – simple as that. And it’s not all linear! New 3D glasses use a circular polarization to make the experience even more pleasant and the image better than ever. It’s safe to say that 3D movies will be sticking around for a long time.