Fibre optics TIR Uses –endoscopes - communications

Lower refractive index cladding Highly transparent glass Use of cladding -minimises absorption -crossover avoided, secure signal Rays in the fibre which reach the cladding boundary with low angles of incidence will not undergo TIR The cladding ensures that all rays in the signal have a large angle of incidence and hence they will be less likely to be lost from the fibre This makes it less likely that light gets into an adjacent fibre (crossover)

If all rays travel along the axis of the fibre the pulse (information) arrives at the other end of the fibre with no distortion of the signal.

rays travelling along different paths travel different distances along the core this causes the received pulse to become longer and means that success pulses of information may merge together this effect is known as multi-path distortion narrow diameter fibres are used as the core to minimise this effect

Spectral dispersion of white light is when the signal is split up (spread out) Monochromatic light (IR radiation) used to avoid this problem