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Hopkins, Harold Horace

fibres optical light electrical

(1918–94) British optical physicist.

Hopkins was educated at Leicester and London and was professor of applied optics at Reading from 1967–84. After N S Kapary’s early proposals in 1955, work by many groups greatly advanced fibre-optics, with contributions by A C S Van Heel and by Hopkins of high value. Optical fibres of plastic or glass (pure silicon dioxide is suitable) are used; they guide light by trapping it through total internal reflection. Their diameter is of the order 0.01 mm and the light-carrying core has an outer cladding to confine the light. A bundle of such fibres is used in flexible endoscopes, which can be inserted through natural or surgical apertures to give direct viewing within the body, of great value in medical diagnosis and in ‘keyhole’ surgery.

Optical fibres also find application in communication systems; undersea fibre-optic cables for telephone services cross the Atlantic and Pacific oceans. Light signals, like electrical signals, can be transmitted and processed in either analogue or digital form. Optical fibres have advantages over electrical wiring in their smaller size and lower weight and in their freedom from electrical interference. A variety of information-carrying uses will certainly continue to develop.

As well as his major work on flexible endoscopes, Hopkins did much to develop the variable zoom lens now widely used by photographers and in television cameras.

Hopkins, Sir Frederick Gowland [next] [back] Hooks, Robert (1937–)

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