Patent ID: 9140582
Filing Date: 2015-09-22
Classification: E21B,G01D,G01F,G01H,G01M,G01V

Abstract:
1. An interferometer apparatus for an optical fibre system, the apparatus comprising: an optical coupler having an input port and first and second ports coupled to optical fibres which define first and second optical paths; first and second Faraday rotator mirrors arranged respectively at the ends of the first and second optical paths to reflect light propagating in the first and second optical paths back to the optical coupler to generate an interference signal; wherein the optical coupler is configured to direct first and second interference signal components of the interference signal respectively to first and second detector ports, and is configured to direct a third interference signal component of the interference signal towards the input port, and the apparatus comprises means for introducing a phase shift between the first, second and third interference signal components; first and second photodetectors connected to first and second detector ports of the optical coupler and configured to measure an intensity of the first and second interference signal components at respective phase shifts; a third photodetector connected to a non-reciprocal optical device and configured to measure the intensity of the third interference signal component directed back towards the input port; an incoherent light source configured to propagate light in the interferometer apparatus; and calibration circuitry configured to: