Materials, methods of making, and methods of sensing liquid droplets with high spatial resolution as a signature of the on-set of corrosion using a hierarchical sensor network A hierarchical sensor network for sensing liquid droplets with high spatial resolution as a signature of the on-set of corrosion, including an interrogation system; and an intermediate sensor array layer in communication with the interrogation system. The network includes an interrogation system and an intermediate sensor array layer in communication with the interrogation system.

In accordance with embodiments there is provided manufacturing processes for fibre optic sensors. In an example, a portion of a fiber optic cable is coated with a thin film layer and placed in a channel of a fiber carrying flexible member for a fiber optic sensor. The portion is embedded in the channel using one of: a thermal curing process after filling the channel with a metallic liquid suspension or polymeric adhesive; and an electroplating or electroless plating process. Filling the channel may comprises performing a controlled dispensing using an automated process such as a drop-on-demand deposition process. In an example, a fiber optical cable is placed in a channel of a flexible member. Micro-laser welding or electron beam welding is used to locally melt the member areas adjacent to the cable resulting in the flow of liquid around the fiber creating a solid structure with embedded fiber after solidification.

In some implementations, a device may obtain responsivity data for segments of a fiber optic cable. The device may receive, from a sensor device, vibration data associated with the fiber optic cable, the vibration data being produced by a vibration source in or on soil associated with the fiber optic cable. The device may normalize, based on the responsivity data, the vibration data. The device may determine, based on the normalized vibration data, a distance of the vibration source from the fiber optic cable. The device may perform one or more actions based on the distance satisfying a distance threshold.

A fibre-optic measurement system equipped with a controlled light generation system (1) and a receiving system (2) connected via an optical path which comprises a directional device (4) and which, in addition, has a processing unit (9) for controlling the light generation system (1) and for receiving and processing the signal from the receiving system (2), according to the invention, it is characterized by the fact that it has a selective mode device (5) and is adapted to be connected to a fibre-optic telecommunications network by a selective mode device (5) and the processing unit (9) is adapted to implement the OFDR and/or COTDR measurement technique for measuring changes in the optical distance and processing them into one or more parameters. Moreover, the object of the invention is also the method of adaptation of a telecommunications network into a sensor network and a fibre-optic measurement and communication system.

Aspects of the present disclosure describe the localization of a utility pole by distributed fiber sensing of aerial fiber cable suspended from the utility pole.

A system for monitoring of the resin front during resin infusion into a fiber preform for the manufacturing of composites. Such monitoring is based on Optical Frequency Domain Reflectometry by emitting light pulses through optic fibers which forms a resin infusion mesh in a fiber preform.

Described herein is a method and system for distributed fibre optic sensing in particular across multiple fibre optic ports with multiple corresponding fibre optic paths. In general, the disclosed method and system includes the steps of (a) repeatedly transmitting a train of optical signals through a fibre optic network including a plurality of optical fibres distributed across a geographic area using at least one optical signal transmitter, (b) sequentially distributing optical signals in the train through the plurality of optical fibres via corresponding optical fibre ports using an optical switching arrangement, (c) receiving backscattered optical signals from the plurality of optical fibres, the backscattered optical signals being influenced by disturbances that induce fibre optic sensing signals, including low frequency weight-induced disturbances, (d) demodulating data from the backscattered optical signals, and processing the data to identify at least some of the low-frequency weight-induced disturbances, and/or (e) sensing the backscattered optical signals in a reduced frequency range, thereby reducing the corresponding required sampling rate and increasing the predetermined multiplex or switching ratio or the number of optical fibre ports serviced per optical signal transmitter/receiver. The disclosed method and system may be useful to provide efficient usage of hardware resources. The disclosed method and system may also be useful to detect low frequency weight-induced disturbances for object tracking against high noise clutter in the higher frequency signal bands.

The present invention concerns apparatus (1) for obtaining distributed pressure measurements in a wellbore (2), the apparatus (1) comprising: a flexible rod (10; 110) arranged to be disposed in the wellbore (2); and an elongate sensing member (15; 115) extending along the rod, the sensing member comprising at least one optical sensing fibre member (16; 116) arranged to afford a continuous length of sensing capability, wherein the sensing member extends in a groove formed in the exterior surface of the rod.

A distributed sensing apparatus based on Optical Time Domain Reflectometry, OTDR, including an optical source; an optical splitter in optical communication with the optical source, the optical splitter having first and second outputs; a sensing fibre in optical communication with the first output of the optical splitter; a combining unit arranged to combine a reference signal derived from the second output of the optical splitter with a backscattered signal derived from the sensing fibre, wherein the combining unit comprises one or more 3×3 fused fibre couplers; and a signal processing unit configured for processing information derived from the combining unit so as to provide distributed sensing data. The combining unit includes a polarization diversity arrangement including one or more polarization sensitive elements.

A system and method for determining an object characteristic from a timed sequence of measured characteristics wherein the object characteristic is determined based on a comparison of a current measured characteristic against a variable reference characteristic. The variable reference characteristic is selected by iterating through the timed sequenced and determining a separate quality metric for the current measured characteristic against each earlier measured characteristic and selecting the variable reference as a function of the determined quality metrics. In one embodiment, iteration continues only until an earlier measured characteristics is found with a quality metric that meets or exceeds a threshold value. In another embodiment, iteration continues through a plurality of earlier measured characteristic (perhaps all) and the variable reference is selected as the earlier measured characteristic with the highest quality metric. The measured characteristics may include OFDR measurements.