Methods and apparatuses to obtain increased performance and differentiation for an inductive position sensor through improvements to the sense element and target design are disclosed. In a particular embodiment, a sense element includes a transmit coil, a first receive coil that includes a first plurality of arrayed loops, wherein two or more of the first plurality of arrayed loops are at least one of phase blended and amplitude arrayed, and a second receive coil that includes a second plurality of arrayed loops, wherein two or more of the second plurality of arrayed loops are at least one of phase blended and amplitude arrayed, and wherein the first receive coil and the second receive coil are phase shifted. The sense element coils are arrayed in several geometries and layouts, and the coil and target geometry are manipulated to compensate for inherent errors in the fundamental design of an inductive position sensor.

Optical fibre based measurement system having a system for generating radiation (Z) with monotonically tuneable wavelength during sweep periods, an optical path (T) and a detector (D) connected to the system for generating radiation (Z) via the optical path (T). The optical path (T) comprises the interferometer (I) comprising the multi-port element (EW) and the attached measuring optical fibre (F) sensitive to at least two environmental parameters, the mode excitation system (P) adapted for excitation in the measuring optical fibre (F) of at least the measuring mode (Mnl) with the first effective refractive index and the measuring mode (Mn2) with the second effective refractive index, having different sensitivity to these two parameters. The measurement system comprises the processing unit (UP) to which the detector (D) is connected via the analogue-to-digital converter (ADC), and the processing unit (UP) is adapted to generate the control signal for the system for generating radiation (Z). The object of the invention is also the method of measuring at least two parameters, and the computer program product.

A long range optical fiber sensor such as a distributed acoustic sensor has a sensing fiber located remotely from the interrogator, with a length of transport fiber path connecting the two. Because no sensing is performed on the transport fiber then the pulse repetition rate from the interrogator can be high enough such that the pulse repetition rate and pulse power are optimised according to the sensing fiber length and hence sensing frequency response and sensitivity are also optimised according to the sensing fiber length.

The subject matter of this specification can be embodied in, among other things, a method for remotely sensing vibration includes transmitting a collection of optical pulses through an optical fiber at a predetermined frequency, detecting a collection of backscattered Rayleigh traces from the optical fiber based on a vibration of the optical fiber at a vibration frequency at a location along the optical fiber, determining a normalized differential trace based on the collection of Rayleigh traces, determining, based on the normalized differential trace, the location in the optical fiber of the vibration, and determining, based on the raw Rayleigh traces, the vibration frequency.

An apparatus for locating a measurand anomaly, such as a hot-spot, along an optical waveguide is provided comprising: an optical waveguide, a light source configured to transmit pulsed light along the waveguide, and a first and second set of sensors provided along the waveguide. Each sensor is configured to reflect a portion of light propagating along the waveguide at a respective sensor wavelength corresponding to a measurand. The first set of sensors provides one or more groups of sensors configured to detect a measurand anomaly within that group. The second set comprises a plurality of sensors each separated from the adjacent sensor of that set by a distance along the waveguide greater than half the distance travelled by the light along the waveguide during the pulse duration. A plurality of sensors of the first set is provided between each adjacent sensor of the second set. The apparatus further comprises a detector configured to monitor the light reflected by the sensors, and a control system configured to control the light source and the detector to both locate at least the group containing a measurand anomaly and to monitor the measurand using the second set.

In some examples, a microstructured fiber comprises a cladding material surrounding at least one core material, wherein the at least one core material comprises an array of discrete devices contacted in parallel. A method of producing a microstructured fiber may include 3D-printing a fiber preform, thermally drawing the fiber preform into a fiber that preserves the cross-sectional geometry of the fiber preform, and axially patterning the fiber into a microstructured fiber comprising an array of discrete devices contacted in parallel. In some embodiments, microstructured fibers may be integrated into a sensory textile that includes at least one of an electrooptic portion, a sonar portion, a magnetic gradiometer portion, and a piezogenerating portion. In some embodiments, microstructured fibers may be formed into an in-fiber integrated quantum device circuit or an in-fiber ion trap.

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.

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.

A fiber optic sensor and a related method of manufacture are provided. The fiber optic sensor includes an embedded optical fiber contained within a metal diaphragm assembly, where the terminal end of the optical fiber is positioned opposite a diaphragm. The method includes forming a metal-embedded optical fiber by ultrasonic additive manufacturing and securing the metal-embedded optical fiber to a housing having a diaphragm that is opposite of the terminal end of the optical fiber. The sensor can provide extremely accurate pressure measurement at high temperatures and in highly corrosive media. An optical fiber-based pressure sensing system is also provided.

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.