Bundles of optical fibres are also used in endoscopes to inspect otherwise inaccessible parts of machines or of the living body.They can carry more data and are more reliable. Optical fibres are increasingly being used to replace metal telecommunication cables, the messages being encoded as digital pulses of light rather than as fluctuating electric current.They are used in bundles to transmit light to or receive light from inaccessible places, by repeated totally internal reflections within the fibre.Optical fibres usually have polished surfaces coated with a material of suitable refractive index so that there is no loss of light through the sides of the fibre.Optical fibres are very fine, optically pure glass fibre through which light undergoes total internal reflection to transmit data from one end to the other. When a light ray is reflected, the angle of incidence angle of reflection Therefore, the angle of incidence (and reflection) is 90° 25° 65. ![]() ![]() When the angle of incidence is greater than the critical angle, all the light undergoes reflection.Īpplication of total internal reflection: Optical Fibres At this point, the angle of incidence is known as the critical angle C This angle can be found using the formula. The angle of incidence must be greater than a certain angle, called the critical angle.įor a ray of light passing from an optically denser to a less dense medium, critical angle, c, is the angle of incidence at which the angle of refraction is $90^$.Light ray travel from an optically denser medium to a less dense medium.Total internal reflection refers to the complete reflection of a ray of light within an optically-denser medium from the surrounding surfaces of optically less dense media back into the denser medium.
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