An optical fibre is a thin rod of high-quality glass. Very little light is absorbed by the glass. Light getting in at one end undergoes repeated total internal reflection, even when the fibre is bent, and emerges at the other end.
Uses of optical fibres
Optical fibres are used in endoscopes that allow surgeons to see inside their patients.
Optical fibres can also carry enormous amounts of information as pulses of light.
Mark Miodownik describes how optical fibres were developed in medicine and explains how they work by demonstrating total internal reflection