An optical sensing system comprising an optical fiber, a light source, a first interrogator and a second interrogator. The optical fiber includes one or more optical sensors. The light source is placed at a first end of the optical fiber and is configured to direct light towards the one or more optical sensors. The first interrogator is placed at the first end of the optical fiber. The second interrogator placed at a second, opposite end of the optical fiber. The first interrogator is configured to receive reflected light from the one or more optical sensors, and the second interrogator is configured to receive transmitted light from the one or more optical sensors.

A slight movement of the ground is detected. A cable, which includes an optical fiber, is provided to have friction with the ground in such a way that the optical fiber is expanded and contracted in accordance with the movement of the ground. An optical output unit outputs a monitoring light to the optical fiber. A partial reflection unit is provided on a path of the optical fiber in the cable and partially reflects the monitoring light. An optical reception unit receives a reflection light reflected by the partial reflection unit. A calculation unit measures the length of the optical fiber to the partial reflection unit based on a round-trip propagation time of the reflection light that has been received and monitors its changes over time.

Systems and methods for performing the dynamic anomaly localization of utility pole aerial/suspended/supported wires/cables by distributed fiber optic sensing. In sharp contrast to the prior art, our inventive systems and methods according to aspects of the present disclosure advantageously identify a location region on a utility pole supporting an affected wire/cable, thereby permitting the identification and reporting of service personnel that are uniquely responsible for responding to such anomalous condition(s).

Use of a sensor read out system with at least one fiber optical sensor, which is connected via at least one signal line to a processing unit as part of an additive manufacturing setup, for in situ and real time quality control of a running additive manufacturing process. Acoustic emission is measured via the at least one fiber optical sensor in form of fibers with Bragg grating, fibre interferometer or Fabry-Perot structure, followed by a signal transfer and an analysis of the measured signals in the processing unit, estimation of the sintering or melting process quality due to correlation between sintering or melting quality and measured acoustic emission signals and subsequent adaption of ion and electron beams, microwave or laser sintering or melting parameters of a ion and electron beams, microwave or laser electronics of the additive manufacturing setup in real times via a feedback loop as a result of the measured acoustic emission signals after interpretation with an algorithmic framework in the processing unit.

An improved optical fiber distributed acoustic sensor system uses an optical fiber having reflector portions distributed along its length in at least a first portion. The reflector portions are positioned along the fiber separated by a distance that is equivalent to twice the distance an optical pulse travels along the fiber in a single sampling period of the data acquisition opto-electronics within the sensor system. No oversampling of the reflections of the optical pulses from the reflector portions is undertaken. The sampling points for data acquisition in the sensor system are aligned with the reflections that arrive at the sensor system from along the sensing fiber. Adaptive delay componentry adaptively aligns the reflected optical signals (or their electrical analogues) with the sampling points. Control over the sampling points can re-synchronise the sampling points with the returning reflections. Reflection equalisation componentry may reduce the dynamic range of the returning reflections.

Distributed sensing systems and methods with spatial location correlation of a reflection produced along an electromagnetic (EM) waveguide. A distributed sensing system comprises an EM waveguide, a distributed sensing interrogator, and a processor. The distributed sensing interrogator comprises a transmitter coupled to the EM waveguide and generates an interrogation pulse through the EM waveguide. The distributed sensing interrogator also comprises a receiver coupled to the EM waveguide and responsive to backscattered EM waves propagating through the EM waveguide. The processor determines a spatial location associated with a reflection produced along the EM waveguide using a return signal generated from the reflection by the interrogator and an interrogation signal including the interrogation pulse.

Distributed sensing systems and methods with spatial location correlation of a reflection produced along an electromagnetic (EM) waveguide. A distributed sensing system comprises an EM waveguide, a distributed sensing interrogator, and a processor. The distributed sensing interrogator comprises a transmitter coupled to the EM waveguide and generates an interrogation pulse through the EM waveguide. The distributed sensing interrogator also comprises a receiver coupled to the EM waveguide and responsive to backscattered EM waves propagating through the EM waveguide. The processor determines a spatial location associated with a reflection produced along the EM waveguide using a return signal generated from the reflection by the interrogator and an interrogation signal including the interrogation pulse.

This application relates to methods and apparatus for distributed fibre optic sensor and especially to Rayleigh based distributed fibre optic sensing that provides enhanced or additional information, such as information regarding large amplitude strains. A sensor has an interrogator (102) for interrogating a sensing optical fibre (101) to perform distributed acoustic sensing and provide a measurement signals from each of a plurality of channels corresponding to sensing portions of the sensing optical fibre. A processor (106, 107) analyses the measurement signals to detect a first characteristic signature (203), the first characteristic signature being a variation in the measurement signal from a plurality of channels that applies for a first channel and substantially all downstream channels and which occurs simultaneously on all such channels.

Example embodiments include an optical interrogation system with a sensing fiber having a single core, the single core having multiple light propagating modes. Interferometric apparatus probes the single core multimode sensing fiber over a range of predetermined wavelengths and detects measurement interferometric data associated with the multiple light propagating modes of the single core for each predetermined wavelength in the range. Data processing circuitry processes the measurement interferometric data associated with the multiple light propagating modes of the single core to determine one or more shape-sensing parameters of the sensing fiber from which the shape of the fiber in three dimensions can be determined.

This invention relates to a force and moment balance (1) including a support (9) therefor and more specifically, but not exclusively, to a force and moment balance (1) and a support (9) therefor for a wind tunnel. Force and moment balances are known in the art and are typically used in wind tunnels to measure the force and moment loads on a model in the wind tunnel. A problem with current balances is that there is inherent vertical movement associated with horizontal force. According to the invention, the balance (1) has a fixed end (3) and a movable end (6) with a number of supports (9) between the fixed end (3) and the movable end (6). Each support (9) includes compensation means to compensate for resultant movements caused by lateral movement of the movable end (6) relative to the fixed end (3).