A surface shape determination system includes a surface shape sensor in the form of a flexible and stretchable elastomeric substrate with strain/displacement sensing elements embedded in it. The sensor may be a single-core optical fiber with a series of fiber Bragg Gratings (FBGs) located at predetermined positions along its length. A light source provides an incident light spectrum at one end of the fiber. Each grating of the fiber has index modulation which causes particular wavelengths of the light spectrum that do not satisfy the Bragg condition to be reflected back in the fiber. The refractive index of each grating changes with strain on the substrate due to deflection of it. An interrogator captures the reflected wavelengths and retrieves signal information therefrom. A processor receives the output of the interrogator and performs non-linear regression analysis on the information using a neural network to reconstruct the surface morphology in real-time.

Discloses is a precipitation measuring apparatus using a fiber Bragg grating sensor, which includes: a base horizontally installed at a position for measuring precipitation; a cylindrical cover fixedly installed on the base; a bucket for collecting a predetermined amount of water introduced into the cover to discharge the collected water; and a detecting unit for detecting the number of times of discharging the water from the bucket by using the fiber Bragg grating sensor, wherein the change in the load applied onto the water collecting tank at a predetermined amount of water discharged from the bucket is detected using the fiber Bragg grating sensor, and the amount of precipitation is precisely measured using the number of changes in the wavelength of the light outputted from the fiber Bragg grating sensor.

This application describes a fibre optic cable structure which is advantageous for distributed fibre optic sensing, for example distributed acoustic sensing (DAS). The fibre optic cable structure includes an optical fibre for distributed fibre optic sensing and is configured to comprise at least one longitudinal section of a first type, which exhibits a change in effective optical path length of the optical fibre of one polarity in response to a given applied force, and which is adjacent to at least one longitudinal section of a second type, which exhibits a change in effective optical path length of the optical fibre of the opposite polarity in response to an equivalent applied force. When used for DAS, the response of a sensing portion that includes sections of both the first and second types, will include or exclude certain wavenumber by summation, which provides a directional sensitivity to incident waves.

A fiber optic distributed acoustic sensing (DAS) system for detecting a red palm weevil (RPW) includes an optical fiber configured to be wrapped around a tree and a DAS box connected to the optical fiber. The DAS box includes a processing unit that is configured to receive a filtered Rayleigh signal reflected by the optical fiber, and run the filtered Rayleigh signal through a neural network system to determine a presence of the RPW in the tree.

An apparatus has a chassis having a base. A first wall extends substantially perpendicularly from the base at a first edge of the base. The first wall is configured to be a first attachment point for an optical cable comprising one or more optical sensors. An opposing second wall extends substantially perpendicularly from the base at a second edge of the base. A mobile attachment point is configured to be a second attachment point for the optical cable. A spring is coupled to the second wall and the mobile attachment point. The spring is configured to provide a specified force as the mobile attachment point moves.

An apparatus includes one or more stamps configured to install an optical fiber on a surface of a structure. Each stamp includes a backing. A first adhesive is disposed on one or more first regions of the backing and is configured to provide a temporary bond between the optical fiber and the surface. A second adhesive is disposed on at least a second region of the backing and is configured to provide a substantially permanent bond between the optical fiber and the surface. A liner is removably adhered to the first adhesive.

The high sensitivity provided by an enhanced DAS system comprising a DAS interrogator and a high reflectivity fiber allows for the deployment of such a high reflectivity fiber as part of a wireline intervention cable which can be temporarily lowered into a well, thus avoiding the need to permanently cement such a high reflectivity optical fiber cable into the well. Instead, such a wireline cable incorporating the high reflectivity optical fiber has been found to be sensitive enough to detect micro-seismic activity and low frequency strain with many more measurement points and channels than conventional wireline deployed geophones and tiltmeters. Additionally, the cable requires no clamping and can be easily and quickly removed from one well and placed in another well.

An optical fiber sensor includes optical sensor elements, for instance a plurality of multiplexed Bragg gratings, a broadband optical source, an interferometer with at least one polarization-maintaining fiber section with which a birefringence modulator, a signal generator and a receiver are associated. The optical birefringence in the propagation medium, i.e., in the polarization-maintaining fibre, combined with the birefringence of the birefringence modulator, produce in the interferometer the path difference and thereby the interference fringes which, appropriately processed according to the known technique, allow the measurement to be traced. The use of a birefringence modulator associated with the polarization-maintaining fiber allows a high-speed modulation of the interferometer, thus allowing high sampling rates of the sensor without having variations in responsivity depending on the alignment of the sensors with the interferential fringes of the interferometer.

Disclosed herein is a system, apparatus and method directed to detecting damage to an optical fiber of a medical device. The optical fiber includes one or more core fibers each including a plurality of sensors configured to (i) reflect a light signal based on received incident light, and (ii) alter the reflected light signal for use in determining a physical state of the multi-core optical fiber. The system also includes a console having non-transitory computer-readable medium storing logic that, when executed, causes operations of providing a broadband incident light signal to the multi-core optical fiber, receiving reflected light signals, receiving reflected light signals of different spectral widths of the broadband incident light by one or more of the plurality of sensors, identifying at least one unexpected spectral width or a lack of an expected spectral width, and determining the damage has occurred to the optical fiber based on the identification.

There is described a method for interrogating optical fiber comprising fiber Bragg gratings (“FBGs”), using an optical fiber interrogator. The method comprises (a) generating an initial light pulse from phase coherent light emitted from a light source, wherein the initial light pulse is generated by modulating the intensity of the light; (b) splitting the initial light pulse into a pair of light pulses; (c) causing one of the light pulses to be delayed relative to the other of the light pulses; (d) transmitting the light pulses along the optical fiber; (e) receiving reflections of the light pulses off the FBGs; and (f) determining whether an optical path length between the FBGs has changed from an interference pattern resulting from the reflections of the light pulses.