This patent application discloses techniques and devices for sensing or measuring electric currents and/or temperature based on photonic sensing techniques. An optical current sensor head is located near or at a current-carrying conductor so that a magnetic field associated with the current is present at a Faraday material and the optical detection unit detects the light from the Faraday material to determine a magnitude of the current. An optical temperature sensor head is located near or at a location so that the temperature at a temperature-sensing Faraday material is reflected by the optical polarization rotation which is detected to determine the temperature.

A magnetic field sensor element 1 includes a light emitter 10 emitting a first linearly polarized light, a first optical element 20 emitting a first linearly polarized wave and the second linearly polarized wave in response to a first linearly polarized light incident, and emitting a second linearly polarized light in response to a third linearly polarized wave and the a linearly polarized wave incident, at least one pair of magnetic field sensor elements 50 capable of disposing in a predetermined magnetic field across the measured conductor, having a light transmissive, changing the phase of transmitted light in accordance with the magnetic field, and fixing a relative position therebetween, an optical path 30 including a first optical path propagating the first linearly polarized wave and the fourth linearly polarized wave, and a second optical path propagating the second linearly polarized wave and the third linearly polarized wave, and connected to the first optical element and the magnetic field sensor element, a detected signal generator 60 outputting a detected signal corresponding to the magnetic field, by receiving two components of the second linearly polarized light, and converting to the electrical signal, and an optical branching element transmitting the first linearly polarized light to the first optical element and branching the second linearly polarized light to the detected signal generator.

A method for emission testing of a semiconductor device (DUT), by mounting the DUT onto an test bench of an emission tester, the emission tester having an optical detector; electrically connecting the DUT to an electrical tester; applying electrical test signals to the DUT while keeping test parameters constant; serially inserting one of a plurality of shortpass filters into an optical path of the emission tester and collecting emission test signal from the optical detector until all available shortpass filters have been inserted into the optical path; determining appropriate shortpass filter providing highest signal to noise ratio of the emission signal; inserting the appropriate shortpass filter into the optical path; and, performing emission testing on the DUT.

A voltage sensor includes an oscillator that has a circular or roughly circular shape and is supported by a mechanical support member, a fixed electrode that has a predetermined gap between the oscillator and the fixed electrode, and a drive electrode that is placed at a position different from the fixed electrode across the oscillator, and to which an AC drive voltage is applied to make the oscillator oscillate. In the voltage sensor, an electrostatic attractive force acts on the oscillator by applying a voltage to the fixed electrode, and a resonance frequency of the oscillator changes.

It is proposed a method for monitoring an electrical power supply line comprised in a seismic cable and extending along the seismic cable. The seismic cable includes: a plurality of seismic sensors arranged along the seismic cable, a plurality of controllers arranged along the seismic cable, and an optical transmission line extending along the seismic cable for carrying data signals from or towards the controllers. The electrical power supply line supplies at least one pair of master and slave controllers. The master controller of a given pair of master and slave controllers performs a step of monitoring a portion of the electrical power supply line between the master and slave controllers, by using an optical loop established on a portion of the optical transmission line between the master and slave controllers, and starting from the master controller and passing through the slave controller.

It is proposed a method for monitoring an electrical power supply line comprised in a seismic cable and extending along the seismic cable. The seismic cable includes: a plurality of seismic sensors arranged along the seismic cable, a plurality of controllers arranged along the seismic cable, and an optical transmission line extending along the seismic cable for carrying data signals from or towards the controllers. The electrical power supply line supplies at least one pair of master and slave controllers. The master controller of a given pair of master and slave controllers performs a step of monitoring a portion of the electrical power supply line between the master and slave controllers, by using an optical loop established on a portion of the optical transmission line between the master and slave controllers, and starting from the master controller and passing through the slave controller.

A magneto-optical sensor for sensing a current flowing through a conductor includes a light source capable of providing a linearly-polarised optical beam, and a polarisation analyser configured to perform a differential measurement of two polarisation components of the linearly-polarised optical beam having travelled along an optical path arranged between the light source and the polarisation analyser. The optical path forms a closed trajectory around the conductor. The sensor comprises a cell containing an atomic gas arranged along the optical path.

Disclosed is an optical fiber winding for measuring the current circulating through a conductor. According to one embodiment the optical fiber winding includes a central support core extending in a longitudinal direction, a first optical fiber cable arranged around the central support core, a second optical fiber cable arranged around the central support core, the first and second optical fiber cables extend in a helical manner around the central support core. According to one embodiment the first optical fiber cable is twisted about its longitudinal axis in a first twist direction, and the second optical fiber cable is twisted about its longitudinal axis in a second twist direction, the first twist direction being opposite the second twist direction. Optical fiber-based current measuring equipment is also disclosed.

In order to measure a voltage, an electro-optic element is placed in an electrical field generated by the voltage, and light is passed from a light source through a Faraday rotator and the electro-optic element onto a reflector and from there back through the electro-optic element and the Faraday rotator, thereby generating a voltage-dependent phase shift between two polarizations of the light. The interference contrast as well as a principal value of the total phase shift between said polarizations are measured and converted to a complex value having an absolute value equal to the contrast and a phase equal to the principal value. This complex value is offset and scaled using calibration values in order to calculate a compensated complex value. The voltage is derived from the compensated complex value.

Optical techniques and sensor devices for sensing or measuring electric currents and/or temperature based on photonic sensing techniques in optical reflection modes by using optical dielectric materials exhibiting Faraday effects are provided in various configurations. The disclosed optical sensing technology uses light to carry and transmit the current or temperature information obtained at the sensing location to a remote base station and this optical transmission allows remote sensing in various applications and provide a built-in temperature calibration mechanism to enhance the measurement accuracy in a range of different temperature conditions.