Uses of Total Internal Reflection

1. Uses of Total Internal Reflection

2. Optic Fibres • A ray of light is bounced along the inside of a solid glass fibre • Ie it uses total internal reflection • Optic fibres are made from glass or plastic with an outside coating of a material with a slightly lower refractive index

3. Construction • Fibre Optic Core: the inner light-carrying member with a high index of refraction. • Cladding: the middle layer, which serves to confine the light to the core.  It has a lower index of refraction. • Buffer: the outer layer, which serves as a "shock absorber" to protect the core and cladding from damage.  The coating usually comprises one or more coats of a plastic material to protect the fibre from the physical environment. Sometimes metallic sheaths are added to the coating for further physical protection.

4. Using an optic fibre • An electrical signal is converted to a pulse of light • The light signal is sent down the fibre • At the receiving end the light pulse is converted back t an electrical signal

5. Problems of thick optic fibres • The ray of light can take several different paths along the inside of the cable. • The end is result is a messy version of the original signal • This is called multipath dispersion

6. Avoiding multipath dispersion • The optic fibre is made with a very narrow core, so that all rays pass almost straight down the core

7. Advantages of Optic Fibres • Can carry huge amounts of data very quickly • Require fewer signal boosters than copper wires • Used for lighting and leisure • Used in medicine e.g. to light small areas and internally • Very difficult to ‘bug’ so are very secure for data transmission • Cannot ‘spark’ so safe is volatile areas