3D Television Technology

The Wave Nature of Light

Light travels from the screen to your eyes, which when collected are interpreted as image. Many 3DTV technologies are based on the polarization of this light. In order to understand how polarization works, it is necessary to understand the wave nature of light.

A wave is defined as a periodic disturbance in a medium or space*, easily visualized by comparison to the ocean rising and falling in water waves. There are two different ways wave may move: longitudinally and transversely. It should be noted that the particles themselves do not "move", but instead "pass" the compression on to the particles next to them, known as wave propagation. For example, when a wave passes through water, the molecules of water move up and down, but do not actually move forward with the wave. To see this, picture a floating stick in a pond; when a gentle wave goes through the pond, the stick will move up and down but not follow the wave (however, a current, which is the movement of particles, will cause the stick to move).

Longitudinal waves, such as sound waves, move in air by compressing the particles in the air in the direction the wave is travelling. Once again, the air particles themselves don't move, only the wave is moving. However, for longitudinal waves to travel, it needs to travel through something. This something can be air, water or even metal. This is why there is no sound in outer space. Light does not need a medium to travel through since it is not a longitudinal wave.

A longitundinal wave propagates by creating compressions in the medium it travels through.[1]

Transverse waves, on the other hand, cause disturbances at right angles to the direction the wave is travelling. This is similar to the way waves in water move or how string vibrate. Light is in fact this kind of wave, but this raises one very important question: what exactly is waving in a light wave?

A transverse wave propagates by creating disturbances at right angles to the direction of propagation.[2]

An electromagnetic wave, propagating leftwards with electric (E) and magnetic (H) fields in perpendicular directions.[3]

Any particular light wave must have a direction perpendicular to the direction of propagation in which the electric field points. This is the basis of polarization, a property of light widely used in 3DTV.