Applications on Total Internal Reflection(Nadiah, Casandra, Wei Chern, Niloy)

Application of Total Internal Reflection:

1. Fibre Optics uses in telecommunications:

There are two types of optical fibre used in telecommunications which are the step-index fibre and the graded-index fibre. The step-index fibre is in which the core is made from one type of glass while the outer cladding has a lower refractive index. The graded-index fibre is when the refractive index of the material gradually decreases outwards from the centre of the fibre.

Before optical fibres were invented, telecommunications used copper cables. Some of the problems that people faced while using the copper cables are that due to the copper’s resistance which changed some energy into heat, signals were reduced and had to be re-amplified every few kilometres.

Advantages: Fibre optics used in telecommunications are far more efficient, less bulky and much cheaper. Some examples are local area networks, cable tv and CCTV.

1. Astronomy; the study of stars and galaxies

Fibre optics are used if several stars and galaxies needs to be studied simultaneously to analyse red-shift or spectra. They are bundled together and placed at the focus of a telescope in a block. Hence, each optical fibre received light from parts of the image of the sky.

Advantages: The fibres will lead the light to an instrument where it can studied by translating the light into an electrical signal and feeding the collected data into a computer.

1. Endoscope or Fibroscope:

An endoscope is any instrument used to look inside the body. Thousands of optical fibres are bundled together in an endoscope which is inserted into a human body so that the doctor can 'see' inside. Light can be directed down the fibres even if they are bent, allowing the surgeon to illuminate the area under observation. He can then view this from a television camera linked to a monitor by coherent fibres. Endoscopes are widely used both in medical and vetenary practices. The physics principle on which they are based is total internal reflection within a fibre optic bundle of fibres.

Advantages: Endoscopes can be used to explore and biopsy such areas as the colon and the bronchi of the lungs. By employing miniature television cameras and tiny surgical implements that allow not only exploration but also endoscopic surgery. Through small incisions; such surgery is much less traumatic to the patient than traditional open surgery. Recovery times are shorter, and less anaesthetic is required.

Other applications:

• Bicycle reflectors
• Binoculars/ Periscopes
• Cutting/carving of the diamonds

Source: http://www.cyberphysics.co.uk/topics/light/TIR.htm

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