Apparatus and method for using a counter-propagating signal method for locating events
First Claim
1. An apparatus for detecting and locating disturbances, comprising:
- at least one light source;
an optical system with at least one optical waveguide, the optical waveguide having at least one detection zone at which a disturbance can occur and affect optical signals from the light source when traveling through the waveguide, in the detection zone, along counter-propagating optical channels;
at least one beam separator between the light source and the optical system, wherein the beam separator couples at least two beams into the optical waveguide for each of the at least two counter-propagating optical channels;
at least one polarization controller operable to manage optical properties of said counter-propagating optical channels, the polarization controller adjusting optical properties for at least one of the optical signals when propagating toward the detection zone;
at least one detector coupled to the optical waveguide and responsive to the optical signals after traversing the detection zone;
a data processing unit coupled to the detector, the data processing unit being operable to localize a place of the disturbance in the detection zone from a difference between times at which effects of the disturbance appear at the detector; and
, a feedback control coupled to the optical system and to at least one said polarization controller, wherein the feedback control and the polarization controller are configured to maximize a signal-to-noise ratio and to minimize a polarization contribution to said difference between times, by at least one of;
seeking a predetermined relationship between polarization phase transformations along the counter-propagating optical channels, maximizing a peak swing in intensity at a point of interference of the beams, and varying an input state of polarization for one of testing and adjusting a balance between said polarization transformations for the counter-propagating channels.
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Abstract
An apparatus and method for using a counter-propagating signal method for locating events is disclosed. The apparatus and method uses a Mach Zehnder interferometer through which counter-propagating signals can be launched. If the sensing zone of the Mach Zehnder interferometer is disturbed, modified counter-propagating signals are produced and the time difference between receipt of those signals is used to determine the location of the event. Polarisation controllers (43, 44) receive feedback signals so that the polarisation states of the counter-propagating signals can be controlled to match the amplitude and/or phase of the signals. Detectors are provided for detecting the modified signals.
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Citations
71 Claims
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1. An apparatus for detecting and locating disturbances, comprising:
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at least one light source;
an optical system with at least one optical waveguide, the optical waveguide having at least one detection zone at which a disturbance can occur and affect optical signals from the light source when traveling through the waveguide, in the detection zone, along counter-propagating optical channels;
at least one beam separator between the light source and the optical system, wherein the beam separator couples at least two beams into the optical waveguide for each of the at least two counter-propagating optical channels;
at least one polarization controller operable to manage optical properties of said counter-propagating optical channels, the polarization controller adjusting optical properties for at least one of the optical signals when propagating toward the detection zone;
at least one detector coupled to the optical waveguide and responsive to the optical signals after traversing the detection zone;
a data processing unit coupled to the detector, the data processing unit being operable to localize a place of the disturbance in the detection zone from a difference between times at which effects of the disturbance appear at the detector; and
,a feedback control coupled to the optical system and to at least one said polarization controller, wherein the feedback control and the polarization controller are configured to maximize a signal-to-noise ratio and to minimize a polarization contribution to said difference between times, by at least one of;
seeking a predetermined relationship between polarization phase transformations along the counter-propagating optical channels, maximizing a peak swing in intensity at a point of interference of the beams, and varying an input state of polarization for one of testing and adjusting a balance between said polarization transformations for the counter-propagating channels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A method for detecting and locating disturbances, comprising:
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establishing an optical system including at least one optical waveguide extending along at least one detection zone at which a disturbance can occur, so as to affect optical signals propagating along counter-propagating optical channels from at least one light source to a detector;
separating from the at least one light source, and coupling into each of the counter-propagating optical channels, at least two beams;
managing optical properties in the counter-propagating optical channels using a polarization controller to vary optical properties for at least one of the optical signals while propagating toward the detection zone;
detecting the optical signals after traversing the detection zone and determining a difference between times at which effects of the disturbance appear in the respective counter-propagating channels after traversing said detection zone;
calculating from said difference between times and localizing in the detection zone a place where the disturbance occurred;
wherein said managing of the optical properties comprises providing a control signal to the polarization controller that maintains a signal-to-noise ratio and minimizes a contribution to said difference between times caused by polarization effects, including at least one of;
seeking a predetermined relationship between polarization phase transformations along the counter-propagating optical channels, maximizing a peak swing in intensity at a point of interference of the beams, and varying an input state of polarization for one of testing and adjusting a balance between said polarization transformations for the counter-propagating channels. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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54. An improved method for detecting and locating disturbances affecting an optical system including at least one optical waveguide extending along at least one detection zone at which a disturbance can occur, thereby affecting optical signals propagating along counter-propagating optical channels from at least one light source to a detector, wherein at least two beams are separated from the at least one light source and coupled into each of the counter-propagating optical channels, and an effect of the disturbance is detected after the beams have traversed the detection zone and a time difference is determined for calculating a location of the disturbance in the detection zone, wherein the improvement comprises:
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managing optical properties in the counter-propagating optical channels using a polarization controller to vary optical properties for at least one of the optical signals while propagating toward the detection zone, wherein said managing includes providing a control signal to the polarization controller that maintains a signal-to-noise ratio and minimizes a contribution to said difference between times caused by polarization effects, and comprises at least one of seeking a predetermined relationship between polarization phase transformations along the counter-propagating optical channels, maximizing a peak swing in intensity at a point of interference of the beams, and varying an input state of polarization for one of testing and adjusting a balance between said polarization transformations for the counter-propagating channels.
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55. An apparatus for locating the position of an event, comprising:
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a light source;
a waveguide for receiving light from the light source so that the light is caused to propagate in both directions along the waveguide to thereby provide counter-propagating optical signals in the waveguide, the waveguide being capable of having the counter-propagating optical signals or some characteristic of the signals modified or affected by an external parameter caused by or indicative of the event to provide modified counter-propagating optical signals which continue to propagate along the waveguide;
detector means for detecting the modified counter-propagating optical signals affected by the parameter and for determining the time difference between the receipt of the modified counter-propagating optical signals in order to determine the location of the event;
a controller for controlling polarisation states of the counter-propagating optical signals so that the signals are amplitude and phase matched; and
wherein the waveguide comprises a first arm for receiving the counter-propagating signals, and a second arm for receiving the counter-propagating signals, the first and second arms forming a Mach Zehnder interferometer. - View Dependent Claims (56, 57, 58, 59, 60, 61, 62, 63, 64)
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65. A method of locating an event comprising the steps of:
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launching light into a waveguide so that the light is caused to propagate in both directions along the waveguide to thereby provide counter-propagating optical signals in the waveguide, the waveguide being capable of having the counter-propagating optical signals or some characteristic of the signals modified or affected by an external parameter caused by the event, to provide modified counter-propagating optical signals which continue to propagate along the waveguide;
substantially continuously and simultaneously monitoring the modified counter-propagating optical signals, so that when an event occurs, both of the modified counter-propagating optical signals affected by the external parameter are detected;
determining the time difference between the detection of the modified signals in order to determine the location of the event;
forming the waveguide as a Mach Zehnder interferometer having a first arm through which the counter-propagating optical signals travel, and a second arm through which the counter-propagating optical signals travel; and
controlling the polarisation states of the counter-propagating optical signals input into the waveguide to provide amplitude and phase matched counter-propagating signals from the waveguide. - View Dependent Claims (66, 67, 68, 69, 70, 71)
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Specification