GB1379648A - Switching apparatus - Google Patents

Abstract

1379648 Optical transmission of information COMPAGNIE GENERALE D'ELECTRICITE 20 July 1972 [21 July 1971] 34070/72 Heading G1A [ Also in Division H4] In a communication system information is transmitted between selectively inter-connected stations via light beams which illuminate holograms which in turn supply luminous flux (of intensity proportional to information signal) to detectors associated with receiving stations. The figure shows a telephone system in which originating subscribers 101 to 104 have separate selector units 110 and 131 to 133 each arranged in response to a dial signal from the associated subscriber to energize one out of five laser diode with an intensity proportional to any speech signal from the subscriber. The resultant beam of coherent monochromatic light passes through a device such as 137 to a hologram element such as 111. The element produces an image beam such as 130 also of intensity proportional to any speech signal from the originating subscriber and extending in a direction such as to impinge on a detector 116, 117, 118, 119 or 120 associated with a terminating subscriber, the direction determining the detector with the hologram co-operates and thus the directory to equipment number translation. A second similar arrangement provides for transmission in the opposite direction. Each selector unit has a separate row of hologram element each utilizing the same detectors and devices 137 to 141 prevent two selector units from connecting to the same detector.