P3.5 - Light and Endoscopes

Refraction is when light changes speed going from one material to another; the wavelength changes and we usually see a change of direction too.

Total Internal Reflection TIR happens when light travelling in a “faster material” surrounded by a “slower material” meets the boundary; if there is a big change in speed and a big change in direction; if the light waves arrive at an angle greater than the Critical Angle (C), then we get ‘TIR.

Surgeons need illumination inside the body to reflect off the…