What are endoscopes used for?. TOTAL INTERNAL REFLECTION. TIR occurs in optical fibres , these are used in endoscopes. Inside Glass. Optical fibres are made of pure glass They are flexible Light is reflected when it strikes the inside surface of the fibre.
TOTAL INTERNAL REFLECTION
TIR occurs in optical fibres , these are used in endoscopes.
When a ray of light enters a glass block at an angle other than the normal it changes speed, wavelength and direction
In going from a less dense medium (air) to a more dense medium (glass) light bends towards the normal.
When a light ray emerges from glass into air it is refracted and bends away from the normal, so i < r.
When i equals the critical angle, the refracted ray is just touching the glass surface.
Glass critical angle: 42 degrees
TIR can occur in prisms and optical fibres