A method of high rate fiber optical distributed acoustic sensing includes injecting a first coherent light pattern comprising first light into an optical cable, the optical cable having at least a first reflector pair and a second reflector pair arranged at different positions along the optical cable; injecting a second coherent light pattern comprising second light into the optical cable while first backscatter light of the first light pattern is propagating in the optical cable; detecting first reflected light originating from reflection of the first light pattern from the first reflector pair and/or the second reflector pair; and, at a different interval in time: detecting second reflected light originating from reflection of the second light pattern from the first reflector pair and/or the second reflector pair.

A monitoring system includes optical sensors disposed on one or more fiber optic waveguides. Each optical sensor is spaced apart from other optical sensors and is disposed at a location along a route defined by a transportation structure that supports a moveable conveyance. The plurality of optical sensors are mechanically coupled to one or both of the transportation structure and the moveable conveyance. Each optical sensor provides an optical output signal responsive to vibrational emissions of one or both of the transportation structure and the conveyance. The monitoring system includes a detector unit configured to convert optical output signals from the optical sensors to electrical signals. A data acquisition controller synchronizes recordation of the electrical signals with movement of the conveyance.

A system 1 for remote sensing of information to be transmitted, said system 1 comprising; an optical time-domain reflectometer, OTDR, 2 adapted to transmit an optical probe signal OPS into an optical fiber 3 and to measure a backscattered signal power; and at least one electro-optical signaling unit 4 connected to said optical fiber 3, wherein the electro-optical signaling unit 4 is configured to change an attenuation and/or a reflection of the optical probe signal OPS depending on at least one signal provided by one or more signal sources 5 in response to the information to be transmitted.

A spectral interrogation device, including: an optical source for emitting a light signal, a measurement optical fibre comprising a series of successive Bragg gratings for reflecting the light signal in different wavelength bands, a reflective optical fibre comprising a total reflection element, a wavelength detector, and an optical switch for switching between a sequence of three operating modes. In a first mode, the light signal emitted by a given optical source is guided from the optical source to a corresponding measurement optical fibre. In a second mode, the light signal is guided to make a predetermined number of return trips in a line formed by a coupling between the measurement optical fibre and a corresponding reflective optical fibre, generating a predetermined delay between the successive gratings. In a third mode, the light signal is guided to a corresponding detector to successively measure the wavelength bands associated with the gratings.

A method is provided for determining temperature changes of an optical fibre having Fiber Bragg Grating patterns provided in at least one portion of the optical fibre. The method involves: emitting light into the optical fibre in a first direction from a first detector arrangement, receiving reflections from the patterns of such emitted light by the first detector arrangement, and processing the reflections for determining a current temperature change related to the optical fibre; and on the basis of predetermined criteria, emitting light into the optical fibre in an opposite, second, direction from a second detector arrangement, receiving reflections from the patterns of such emitted light by the second detector arrangement, and processing the reflections for determining a current temperature change related to the optical fibre. A computer program product comprising program code for implementing the above-described method is also provided, along with an associated system and platform.

The present invention is the optical fiber sensor, that laser pulses from a laser source are separated into a reference path and a measurement path by the second optical coupler via the first optical coupler, the first FRM is provided at an end of the reference path, the second FRM is provided at an end of the measurement path, and the reference reflected light of the first FRM and the measurement reflected light of the second FRM are interfered at the second optical coupler and are converted into three phases. The first phase pulses are transmitted to the optical synthesis section via the first optical coupler, second phase pulses are transmitted to the optical synthesis section via the first delay section, and third phase pulses are transmitted to the optical synthesis section via the second delay section. The time division pulse train is outputted from the optical synthesis section.

An optical sensor and a deformation detection system in which the optical sensor is used. The optical sensor includes an optical fiber, an elongated hollow housing having an interior portion, and a material disposed on an inner surface of the housing that produces a persistent change in an optical signal transmission property of the optical fiber when the optical fiber contacts the material. The optical fiber elastically extends between opposing ends of the housing such that a bending deformation of the housing beyond a threshold radius of curvature causes a contact to occur between the material and the optical fiber. The contact results in persistent change in the optical signal transmission property of the optical fiber, which can be detected to determine whether deformation of the device occurred beyond a predetermined threshold value. The deformation detection system can use one or more of the optical sensors attached to the device.

An optical sensor and a deformation detection system in which the optical sensor is used. The optical sensor includes an optical fiber, an elongated hollow housing having an interior portion, and a material disposed on an inner surface of the housing that produces a persistent change in an optical signal transmission property of the optical fiber when the optical fiber contacts the material. The optical fiber elastically extends between opposing ends of the housing such that a bending deformation of the housing beyond a threshold radius of curvature causes a contact to occur between the material and the optical fiber. The contact results in persistent change in the optical signal transmission property of the optical fiber, which can be detected to determine whether deformation of the device occurred beyond a predetermined threshold value. The deformation detection system can use one or more of the optical sensors attached to the device.

An optical sensor and a deformation detection system in which the optical sensor is used. The optical sensor includes an optical fiber, an elongated hollow housing having an interior portion, and a material disposed on an inner surface of the housing that produces a persistent change in an optical signal transmission property of the optical fiber when the optical fiber contacts the material. The optical fiber elastically extends between opposing ends of the housing such that a bending deformation of the housing beyond a threshold radius of curvature causes a contact to occur between the material and the optical fiber. The contact results in persistent change in the optical signal transmission property of the optical fiber, which can be detected to determine whether deformation of the device occurred beyond a predetermined threshold value. The deformation detection system can use one or more of the optical sensors attached to the device.

An optical sensor and a deformation detection system in which the optical sensor is used. The optical sensor includes an optical fiber, an elongated hollow housing having an interior portion, and a material disposed on an inner surface of the housing that produces a persistent change in an optical signal transmission property of the optical fiber when the optical fiber contacts the material. The optical fiber elastically extends between opposing ends of the housing such that a bending deformation of the housing beyond a threshold radius of curvature causes a contact to occur between the material and the optical fiber. The contact results in persistent change in the optical signal transmission property of the optical fiber, which can be detected to determine whether deformation of the device occurred beyond a predetermined threshold value. The deformation detection system can use one or more of the optical sensors attached to the device.