| 摘要 |
1,200,897. Optical information transmitting system. ENGLISH ELECTRIC CO. March 28, 1968 [March 30, 1967], No.14465/67. Heading G1A. [Also in Division H4] The receiver for a system in which information is conveyed by the angle of polarisation of light in a beam, for example from a laser 15 comprised at least one polarizer 1 for polarising light received from the transmitter at 45 degrees to its mean plane of polarization, and a photo-detector fed by the beam which has passed through the polarizer. Light from a source 15 which need not be in the visible spectrum is polarized by a Nicol prism 17 and modulated with coded information by a Kerr cell 18. The received beam is split into two slightly divergent beams by a Wollaston prism 25 to produce polarization at right angles in the respective beams and at 45 degrees to the polarization of the unmodulated beam. The beams are separately detected, and the resulting signals are applied to a differential amplifier. The coding device may produce pulse-code, pulse-position, pulse-frequency or pulse-width modulation.
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