Fiber-optic cable is another step in advancement of voice and video communication. A better connection can be obtained through fiber-optic cables. In other words, a stable connection is obtained with it, especially for voice communication. Fiber-optic cables are now rapidly introducing among the people. Vast media has proved that fiber-optic cables are much reliable than copper wires.
New networks must also meet the growing demand for faster transmission speeds, especially for sound and video applications. One recently developed network, called an Asynchronous Transfer Mode (ATM) network, has speeds of up to 625 Mbps and can be used by either LANS or WANS. Fiber-optic cables are most likely filling these demands. Fiber-optic cables are cables made of specially treated glass that can transmit signals in the form of pulsed beams of laser light. Fiber-optic cables carry many times more information than copper wires can, and are able to transmit several television channels or thousands of telephone conversations at the same time. Fiber-optic technology is being used to replace copper wires in transoceanic cables and cables in other areas where large amounts of data are sent. New improvements promise cables that can transmit millions of telephone calls over a single fiber,
Fiber Optics is branch of optics dealing with the transmission of light through fibers or thin rods of glass or some other transparent material of high refractive index. If light is admitted at one end of a fiber, it can travel through the fiber with very low loss, even if the fiber is curved. The principle on which this transmission of light depends is that of total internal reflection. Light traveling inside the fiber center, or core, strikes the outside surface at an angle of incidence greater than the critical angle, so that all the light is reflected toward the inside of the fiber without loss. Thus light can be transmitted over long distances by being reflected inward thousands of times. In order to avoid losses through the scattering of light by impurities on the surface of the fiber, the optical fiber core is clad with a glass layer of much lower refractive index; the reflections occur at the interface of the glass fiber and the cladding.
The simplest application of optical fibers is the transmission of light to locations otherwise hard to reach, for example, the bore of a dentist's drill. Also, bundles of several thousand very thin fibers assembled precisely side by side and optically polished at their ends, can be used to transmit images. Each point of the image projected on one face of the bundle is reproduced at the other end of the bundle, reconstituting the image, which can be observed through a magnifier. Image transmission by optical fibers is widely used in medical instruments for viewing inside the human body and for laser surgery, in facsimile systems, in phototypesetting, in computer graphics, and in many other applications.
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