Tuesday, August 2, 2011

Applications of Total Internal reflection - Bernard Ng & Azeem

1) A fiber optic is a glass "hair" which is so thin that once light enters one end, it can never strike the inside walls at less than the critical angle. The light undergoes total internal reflection each time it strikes the wall. Only when it reaches the other end is it allowed to exit the fiber. (http://regentsprep.org/Regents/physics/phys04/captotint/default.htm)

2) Diamonds have high refraction index and are cut to sparkle through Total internal reflection.

3) 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 (an incoherent bundle is used to do this!). S/he can then view this from a television camera linked to a monitor by coherent fibres.
Usually consisting of a fiber-optic tube attached to a viewing device, 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 thy 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 (sometimes none!). (http://www.cyberphysics.co.uk/topics/light/TIR.htm)

4) Some optical instruments, such as periscopes and binoculars use prisms instead of mirrors to reflect light around corners. This is because mirrors do not reflect light as totally as prisms do (mirrors only reflect about 95% of that reflected by prisms under TIR conditions). Also refraction distortion can result in using a glass fronted mirror. Therefore the image is crisper and brighter. In prismatic binoculars, total internal reflection in prisms is used to extend the path length between objective and eyepiece, effectively `folding' the optical path. This makes them compact and easy to carry. ((http://www.cyberphysics.co.uk/topics/light/TIR.htm)

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