A system can calculate estimated strain data for a fracture in a geological formation at each of a plurality of selected locations detectable by a strain measurement device. The system can receive real strain data from the strain measurement device for the geological formation. The system can perform a linear inversion to determine a probable distribution of fluid volume and hydraulic fracture orientation in the geological formation based on the estimated strain data and real strain data. The system can determine adjustments for a fracturing operation based on the linear inversion.

A method for detecting defects in a composite structure, such as in an aircraft structure, that includes sending an optical signal down an optical fiber embedded in the composite structure and analyzing the optical signal at a detector. If it is determined that the optical signal is turning on and off or an increase in the bit error rate is occurring at the detector, the composite structure may be delaminating or the composite structure may be somehow damaged. If it is determined that the composite structure is damaged, the optical signal can be sent down a different optical fiber that may not be at a location where the composite structure is damaged, and a continuous beam of light can be sent down the optical fiber that is at the damaged part of the composite structure to determine whether the damage is increasing.

A sensing system utilizes multiple wavelengths communicated on a single pulse to a sensor, for example, an optical fiber. Backscattered or reflected light from a number of locations or depths along the sensor are analyzed to correct for 2π phase jump error. A phase sensing method detects the 2% phase jump error associated with one or more measurements from the sensor. Correcting for the 2π phase jump error provides increased accuracy of the one or more measurements, for example, improved vertical sensing profiling, production and fracture monitoring, and micro-seismic monitoring.

Brillouin optical distributed sensing device and method is provided and includes a structure for generating an optical pulsed signal and an optical probe signal. The structure includes a circulation component for directing the optical pulsed signal to a sensing optical fiber, and directing an optical measurement signal with Brillouin scattering information arising from the sensing optical fiber toward a detection apparatus. Also included is an optical routing component for configuring the device to allow generating: (i) according to a first configuration, an optical measurement signal with stimulated Brillouin scattering information resulting from the interaction of the optical pulsed signal, and an optical probe signal propagating in the sensing optical fiber in a direction opposite to the optical pulsed signal, or (ii) according to a second configuration, an optical measurement signal with spontaneous Brillouin scattering information resulting from the propagation of the optical pulsed signal in the sensing optical fiber.

This invention relates to a system and method to determine the distributed birefringence profile along an optical fibre. Birefringence manifests as different refractive indices for two orthogonal states of polarization of the light propagating in the optical fibre. The technique is based on the correlation among sets of measurements acquired using phase-sensitive optical time-domain reflectometry (φOTDR), launching light into the fibre with multiple states of polarization. The correlation between the measurements performed while sweeping the laser frequency gives a resonance (correlation) peak at a frequency detuning that is proportional to the refractive index difference between the two orthogonal polarizations. This enables measurements of the local value of the phase birefringence at any position along the optical fibre, so that longitudinal fluctuations of its value can be evaluated. Such fluctuations can be induced either accidentally during cabling and installation processes, or voluntarily due to varying conditions or environmental quantities such as temperature, strain and pressure, or even unintentionally as a result of a badly controlled manufacturing process.

A measurement system includes a cable having a length, a light source, at least one detector, and at least one processor. The light source is operably coupled to the cable and is configured to transmit an optical signal to the cable. The at least one processor is operably coupled to the cable and configured to: receive a scattered signal from the cable responsive to the optical signal transmitted to the cable; map the scattered signal to the length of the cable; and de-convolve a spatial averaging effect of the scattered signal using a weighting profile corresponding to the light source and the cable to generate a distributed property profile defined along the length of the cable.

Overheat and fire detection for aircraft systems includes an optical controller and a fiber optic loop extending from the optical controller. The fiber optic loop extends through one or more zones of the aircraft. An optical signal is transmitted through the fiber optic loop from the optical controller and is also received back at the optical controller. The optical controller analyzes the optical signal to determine the temperature, strain, or both experienced within the zones.

Embodiments of the present invention address aliasing problems by providing a plurality of discrete acoustic sensors along a cable whereby acoustic signals may be measured in situations where the fiber optic cable has not been secured to a structure or area by a series of clamps, as described in the prior art. Acoustic sampling points are achieved by selectively enhancing the acoustic coupling between the outer layer and the at least one optical fiber arrangement, such that acoustic energy may be transmitted selectively from the outer layer to the at least one optical fiber arrangement. The resulting regions of acoustic coupling along the cable allow the optical fiber to detect acoustic signals. Regions between the outer layer and the at least one optical fiber arrangement that contain material which is acoustically insulating further this enhancement since acoustic waves are unable to travel through such mediums, or at least travel through such mediums at a reduced rate.

A registration device includes an attachment piece (106) configured to conform with and attach to an imaging probe (102), in particular an internal or external ultrasound probe such as a TEE probe. A pathway (105) formed in or on the attachment piece is configured to receive an optical shape sensing device (OSS fiber) such that the optical shape sensing device can free float (no tip fixation) to permit longitudinal twisting within the pathway. The pathway includes a distinctive geometry for shaping the OSS device such that the distinctive geometry provides a template pattern (107) within an image collected using the imaging probe module to permit registration between imaging coordinates and OSS coordinates. A registration module (130) is configured to compare a stored shape template (121) with an image (134) including the template pattern to permit the registration (unique transformation).

A cable (10) includes a cable body (11) that is formed from a plurality of wires (14) that are integrally bundled; and a pair of sockets (12) to which both end portions of the cable body (11) is separately affixed; at least one of the plurality of wires (14) being a fiber-containing wire (16), which is formed by an optical fiber (17) that extends in a cable length direction (D) and that is protected by a protective tube (18); wherein the optical fiber (17) protrudes from the protective tube (18), in the cable length direction, further outside than the socket (12); and each of the pair of sockets (12) is provided with a spool (30) that removably holds the optical fiber (17) and imparts an initial tensile strain to the optical fiber (17).