Information About

Photophone




The photophone used crystalline and Convex forms, thus focussing or dispersing the light from the light source. The photophone functioned similarly to the telephone, except the photophone used light as a means of projecting the information, while the telephone relied on Electricity .

In one experiment in Washington, D.C. , Bell and his co-inventor Charles Sumner Tainter succeeded to communicate clearly over a distance of some 700  Ft . (about 213  M ), using plain sunlight as the light source. The receiver was a Parabolic mirror with the selenium cells in its focal point. The selenium cells had an electrical resistance varying between 300  Ω and 100  Ω .

Although the photophone was an extremely important invention, it was many years before the significance of Bell's work was fully recognized. Bell's original photophone failed to protect transmissions from outside Interference s, such as clouds, that easily disrupted transport. Until the development of modern Fiber Optic s, technology for the secure transport of light inhibited use of Bell's invention. Bell's photophone is recognized as the progenitor of the modern fiber optics that today transport over eight percent of the world's Telecommunication s.


LITERATURE


  • Bell, A. G.: "On the Production and Reproduction of Sound by Light", ''American Journal of Sciences'', Third Series, vol. XX, #118, October 1880 , pp. 305 - 324; also published as " Selenium and the Photophone" in '' Nature '', September 1880 .



EXTERNAL LINKS