INTERFEROMETRIC APPARATUS

摘要

Interferometric apparatus for use as a data ring or detector of magnetic fields or electric currents, comprises an optical fibre loop (1), a solid state light source (2), a fibre optic directional coupler (3) and a photodiode detector (4). Input light from the light source (2) is polarised and amplitude-divided at the directional coupler (3) into two beams which propagate in opposite directions about the fibre loop (1). After propagating about the loop the two beams are coherently mixed at the directional coupler and the resulting optical interference signal is detected by the photodiode (4). One or more electrical data or signal coils (5, 6, 7) wound about the optical fibre of the loop (1) produce magnetic fields having components in the direction of the optical fibre, whereby the Faraday effect causes rotation of the polarisation azimuths of the counter-propagating beams within the fibre loop. When these azimuth modulated light beams arrive at the directional coupler (3) the resulting interference signal is detected by the photodiode (4) which produces an electrical signal which in turn is processed to recover signals generated by the data or signal coils (5, 6, 7).