The invention enables the measurement of the voltage between phases (phase-to-phase voltages) of a multi-phase power cable, e.g. a three-phase power cable, such as may be used in subsea or subterranean environments for electrical power transfer. The invention does not require a power supply at the measurement location, and relies solely on optical fibres (typically present in such cables) to carry light to and from the sensors. Fibre Bragg grating (FBG) based sensors sample the electric field between conductors and convert to a strain on the fibre, as a result of which certain wavelengths of the reflected light are modulated by the instantaneous magnitude of the phase-to-phase voltages to be measured. A sensor module embodying the invention includes a spacer which holds the conductors in a predetermined geometry and locates the FBG sensors between pairs of conductors on which the phase-to-phase voltage measurements are to be performed. At an end of the cable, an interrogation system can extract and interpret the modulation of these wavelengths to infer the measured values of voltage. The invention may be incorporated into a repair splice for retrofitting purposes, and may also incorporate FBG-based current sensors to simultaneously measure current in the conductors.

In order to carry out the polarimetric detection of a measurand, light of two polarization states is passed through a sensing element, where the two states suffer a differential phase shift depending on the value of the measurand. In order to compensate for only imperfections of the device, a method is proposed that is based on calibration values obtained in a low-value regime of the measurand only. Yet the method can still be used for accurately determining higher values of the measurand.

Embodiments of the invention include a current sensing device for sensing current in an organic substrate. The current sensing device includes a released base structure that is positioned in proximity to a cavity of the organic substrate and a piezoelectric film stack that is positioned in proximity to the released base structure. The piezoelectric film stack includes a piezoelectric material in contact with first and second electrodes. A magnetic field is applied to the current sensing device and this causes movement of the released base structure and the piezoelectric stack which induces a voltage (potential difference) between the first and second electrodes.

Optical fiber-based measuring equipment for measuring the current circulating through at least one conductor. The measuring equipment includes an interrogator and a sensing portion connected to the interrogator and configured for being arranged in the proximity of the conductor. The sensing portion includes a first input branch and a second input branch coupled by means of a splitter to a first sensing branch and to a second sensing branch. The first sensing branch includes a first optical fiber winding arranged in the proximity of the conductor, and the second sensing branch includes a second optical fiber winding arranged in the proximity of the conductor, the first optical fiber winding and the second optical fiber winding having the same number of turns that are, however, wound in opposite directions.

A method for measuring the current circulating through at least one conductor with the use of optical fiber-based measuring equipment is provided. According to one implementation the measuring equipment includes a first emitter that emits a first signal which reaches a sensing branch through a first branch, runs through the sensing branch, and is modified depending on the current circulating through the conductor. A modified first signal is received by a second receiver from a second branch. A second emitter emits a second signal which reaches the sensing branch through the second branch, runs through the sensing branch, and is modified depending on the current circulating through the conductor. A modified second signal is received by a first receiver from the first branch. The current circulating through the conductor is determined by combining the modified first signal and the modified second signal.

A Fast Faraday cup includes a group of electrodes including a ground electrode having a through hole and a collector electrode configured with a blind hole that functions a collector hole. The electrodes are configured to allow a beam (e.g., a non-relativistic beam) to fall onto the ground electrode so that the through hole cuts a beamlet that flies into the collector hole and facilitates measurement of the longitudinal distribution of particle charge density in the beam. The diameters, depths, spacing and alignment of the collector hole and the through hole are controllable to enable the Fast Faraday day cup to operate with a fast response time (e.g., fine time resolution) and capture secondary particles.

A measurement system for real-time visualization of radiation pattern is provided. The measurement system comprises an antenna array with a plurality of antennas configured to provide a voltage gain corresponding to a received radio signal. Furthermore, the measurement system comprises a plurality of radio frequency detectors configured to rectify the voltage gain from each antenna of the plurality of antennas. In addition, the measurement system comprises a plurality of amplifiers downstream of the plurality of radio frequency detectors configured to amplify the magnitude of a rectified voltage from each of the radio frequency detectors. The measurement system moreover comprises a plurality of receiving elements, each includes a light emitting diode and configured to receive an amplified voltage corresponding to each amplifier of the plurality of amplifiers.

A measurement system for real-time visualization of radiation pattern is provided. The measurement system comprises an antenna array with a plurality of antennas configured to provide a voltage gain corresponding to a received radio signal. Furthermore, the measurement system comprises a plurality of radio frequency detectors configured to rectify the voltage gain from each antenna of the plurality of antennas. In addition, the measurement system comprises a plurality of amplifiers downstream of the plurality of radio frequency detectors configured to amplify the magnitude of a rectified voltage from each of the radio frequency detectors. The measurement system moreover comprises a plurality of receiving elements, each includes a light emitting diode and configured to receive an amplified voltage corresponding to each amplifier of the plurality of amplifiers.

The technology of a zero loop-area oblique-incidence Sagnac interferometer and methods of using the Sagnac interferometer to detect magneto-optic Kerr effect is disclosed. An example apparatus includes: a light source configured to generate an optical beam; a beam splitter; a polarizer configured to separate the optical beam into two orthogonal components; a modulator configured to phase-modulating at least one of the two orthogonal components to produce a modulated pair of orthogonal components; a polarization dependent delay optics configured to direct the modulated pair of orthogonal components toward a surface of a sample to cause the modulated pair of orthogonal components to incident on the surface at an oblique angle; a mirror configured to reflecting the modulated pair of orthogonal components back towards the beam splitter; a photo receiver configured to receive a return beam redirected by the beam splitter; and a phase-sensitive detector.

A voltage measuring device for measuring a voltage by using a Pockels cell includes a Pockels cell changing a refractive index of incident light based on an applied electric field, at least one non-polarized beam splitter splitting an incident beam, a first polarizing plate polarizing a first beam split by the at least one non-polarized beam splitter, a first light detector detecting light polarized based on the first polarizing plate, a wave plate elliptically polarizing and outputting a second beam split by the at least one non-polarized beam splitter, a second polarizing plate polarizing the elliptically polarized second beam, a second light detector detecting light polarized based on the wave plate and the second polarizing plate, and a controller configured to measure a voltage based on a first light intensity determined by the first light detector and a second light intensity determined by the second light detector.