How does Stereoscopic 3D TV work?

Human Perception

In terms of perception we, as humans, naturally experience what is known as binocular vision. In simpler terms this means that because we have two eyes we actually perceive two different images at one time which is what allows us to see depth. This theory can be proven in practise by placing an object in front of you and closing one eye and then closing that eye and opening the other one. When you do this It appears like the object shifts to either the left or the right a bit depending on which eye you have closed. When using both eyes simultaneously our brain uses this distance in order to calculate and perceive depth and distance so that we can 'see' it.

3D Television & Active Shutter Glasses

When viewing a 3D movie on a 3D television set the screen actually displays two seperate images at the same time, one superimposed over the other. The distance between these two images is approximately three inches to coincide with the average distance between a person's two eyes. This is known as stereoscopic 3D. However, because the two seperate images are being displayed simultaneously we need to wear 3D glasses to perceive the depth and distance properly. A set of 3D glasses contains an active shutter on each lens. Each of these lenses opens and closes alternately at a speed so rapid it is impossible to notice with the naked eye therefore alternating between the two images and 'fooling' our perception into seeing depth.

3D Gaming Without Glasses & Active Shutter Screens

Recently released is the Nintendo 3DS which offers the ability of 3D gaming without the need for active shutter glasses. Technically the 3DS still offers stereoscopic 3D in exactly the same way that a television set does. However, because there is no need for glasses the quality of the 3D experience is less pronounced as you cannot have images seemingly pop out of the screen and come hurtling towards you like you can with 3D glasses due to the active shutters being right in front of your eyes providing that amount of distance between the glasses (ie you) and the television set.

The Nintendo 3DS (and other handheld 3D devices) work by having the active shutter built into the screen in front of the display. Once again the active shutter works by opening and closing at a rate too fast for the human eye to decipher and displays two alternating (rather than two together) images at a rate so fast that those two images are perceived by the brain as one image with depth.  However, because the active shutter is built into the screen (or in front of it) each eye cannot be fooled seperately.

3DTV Without Glasses

The ability to watch television in 3D without the need to wear glasses is possible by having an active shutter built into the television screen. However, as mentioned above, without glasses each eye cannot be fooled seperately so both eyes must be 'fooled' at the same time which can, at the most, only offer depth and means that the two alternating images cannot be shown simultaneously.   3D television without glasses may be a possibility in the future as there are still many controversial issues surrounding the consequences of active shutter glasses on our health.