Curved fibre optic cables (FOC)

The physical effect which is responsible for the reflection is called "total reflection" and facilitates the conduction of light waves through curved FOC:

 

 

A total reflection occurs when a light beam hits the boundary layer of two transparent media (also called "optical medium") at a flat angle. Every "optical medium" has an "optical thickness". Only when the conditions of this optical thickness are correct and the angle of incidence of the light beam is small enough is there a total reflection. The colour of the light plays a role in this. In FOC only red light with a wave length of 650 nm (nanometers) is used. A nanometer is one millionth of a meter. (10^-12 metre).