A method for measuring a response from an optical fiber providing distributed back reflections using a system comprising an optical source comprising a laser, an optical receiver and a processing unit is disclosed. The method comprises establishing initial parameters of a distributed back-reflection processing. The method also comprises generating an interrogation signal and an optical local oscillator using the optical source, the interrogation signal being represented by an interrogation phasor and the optical local oscillator being represented by a local oscillator phasor; transmitting the interrogation signal into the optical fiber; and mixing the optical local oscillator with reflected light from the optical fiber and detecting a mixing product with the optical receiver to achieve a receiver output signal. The method further comprises performing a measurement that characterizes the interrogation phasor; updating the parameters of the distributed back-reflection processing based on the measurement result such that an effect of fluctuations in the interrogation phasor on the measured response from the fiber is reduced; and applying distributed back-reflection processing to the receiver output signal. Finally, the method comprises extracting the response from the optical fiber from the distributed back-reflection processing output. A system for measuring a response from an optical fiber providing distributed back reflections is also disclosed.

A fiber Bragg grating inclination sensor, including a semicircular substrate and a packaged fiber Bragg grating. The semicircular substrate is fixed on a first structural member. One endpoint of the semicircular substrate is bonded with one end of the packaged fiber Bragg grating, and the other end of the packaged fiber Bragg grating is connected to a second structural member. The first structural member is fixed to the second structural member perpendicular to the first structural member. The packaged fiber Bragg grating is arranged on a tangent to the semicircular substrate. The fiber Bragg grating sensor of the present invention has the advantages of anti-electromagnetic interference and high sensitiveness. The present invention has a simple structure, high measurement accuracy, good stability, thereby having broad application prospects.

A fiber Bragg grating inclination sensor, including a semicircular substrate and a packaged fiber Bragg grating. The semicircular substrate is fixed on a first structural member. One endpoint of the semicircular substrate is bonded with one end of the packaged fiber Bragg grating, and the other end of the packaged fiber Bragg grating is connected to a second structural member. The first structural member is fixed to the second structural member perpendicular to the first structural member. The packaged fiber Bragg grating is arranged on a tangent to the semicircular substrate. The fiber Bragg grating sensor of the present invention has the advantages of anti-electromagnetic interference and high sensitiveness. The present invention has a simple structure, high measurement accuracy, good stability, thereby having broad application prospects.

A linear actuation screw having a first end portion, a second end portion on an opposite side as the first end portion, and a sloping intermediate portion between the first end portion and second end portion. The first end portion has a threaded outer wall having a generally constant first diameter over at least a portion of its length and is configured to advance a nut or a sliding member along at least a portion of the first end portion. The second end portion has a threaded outer wall having a generally constant second diameter that is different from the first diameter and is configured to receive a motor fastening nut around it in order to secure the linear actuation screw to a motor. The sloping intermediate portion includes an outer wall that is generally smooth and continuous over at least a majority of the area of the outer wall.

The present invention provides novel apparatus and methods for fast quantitative measurement of perturbation of optical fields transmitted, reflected and/or scattered along a length of an optical fibre. The present invention can be used for point sensors as well as distributed sensors or the combination of both. In particular this technique can be applied to distributed sensors while extending dramatically the speed and sensitivity to allow the detection of acoustic perturbations anywhere along a length of an optical fibre while achieving fine spatial resolution. The present invention offers unique advantages in a broad range of acoustic sensing and imaging applications. Typical uses are for monitoring oil and gas wells such as for distributed flow metering and/or imaging, seismic imaging, monitoring long cables and pipelines, imaging within large vessel as well as for security applications.

The present invention provides novel apparatus and methods for fast quantitative measurement of perturbation of optical fields transmitted, reflected and/or scattered along a length of an optical fibre. The present invention can be used for point sensors as well as distributed sensors or the combination of both. In particular this technique can be applied to distributed sensors while extending dramatically the speed and sensitivity to allow the detection of acoustic perturbations anywhere along a length of an optical fibre while achieving fine spatial resolution. The present invention offers unique advantages in a broad range of acoustic sensing and imaging applications. Typical uses are for monitoring oil and gas wells such as for distributed flow metering and/or imaging, seismic imaging, monitoring long cables and pipelines, imaging within large vessel as well as for security applications.

A fiber optic sensor device comprising an optical fiber with a multilayer coating on the optical fiber at least in a fiber section of the optical fiber. The multilayer coating comprises a chrome layer on the optical fiber, a metal layer such as a copper layer on the chrome layer and an indium or lead layer on the metal layer. The indium or lead layer having a thickness larger than thicknesses of the chrome and metal layers, preferably with a thickness about equal to the radius of the optical fiber.

A vibration sensing optical fiber cable is provided. The cable includes at least one optical fiber embedded in the cable jacket such that vibrations from the environment are transmitted into the cable jacket to the optical fiber. The cable is configured in a variety of ways, including through spatial arrangement of the sensing fibers, through acoustic impedance matched materials, through internal vibration reflecting structures, and/or through acoustic lens features to enhance sensitivity of the cable for vibration detection/monitoring.

A sensor device including a deflectable membrane made of a 2D nanomaterial, a first optical waveguide for guiding light, disposed adjacent to the membrane and extending along the surface of the membrane at least in a first section, as well as a measuring device for measuring, within the first section the influence of the membrane on an evanescent wave range of the light guided along the first optical waveguide. The influence of the membrane on the light guided in the optical waveguide, in particular on the evanescent wave range of the light, can be measured interferometrically by detecting phasing differences or phase shifts. This allows for a force-free readout of the membrane deflection. By using very thin 2D nanomaterials, the membrane can also react to very quick changes in force.

An apparatus includes an electronic circuit, an electro-acoustic transducer and a coupler. The electronic circuit is configured to receive data to be transmitted over an optical cable, and to convert the data into a modulating signal. The electro-acoustic transducer is configured to convert the modulating signal into an acoustic wave. The coupler is configured to be mechanically coupled to a section of the optical cable, and to apply to the section a longitudinal stretching force that varies responsively to the acoustic wave, so as to modulate the data onto an optical carrier traversing the optical cable.