A sensor head of a test and measurement instrument can include an input configured to receive an input signal from a device under test (DUT), an optical voltage sensor having signal input electrodes and control electrodes or one set of electrodes, wherein the input is connected to the signal input electrodes, and a bias control unit connected to the control electrodes and configured to reduce an error signal or the input signal bias control signal are electrically combined and applied to a single set of electrodes.

A glass ring for current measurements includes a glass body, which can be disposed around an electrical conductor and has a light entry surface and a light exit surface. The glass ring allows light which enters the glass body through the light entry surface to circulate completely around the conductor in the glass body by reflection on external sides or outer faces of the glass body, the light exiting from the glass body on the light exit surface. The glass ring is formed of a monolithic glass body. A method for optical current measurement includes using a current flow in an electrical conductor to generate an electromagnetic field around the conductor, by which a polarization of a light beam in the glass ring around the conductor, in particular with a plane perpendicular to the longitudinal axis of the conductor, is changed as the light beam circulates around the conductor.

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.

The voltage measuring device includes: a light source; a polarizer polarizing light emitted from the light source; a grounded conductor provided apart from a high-voltage conductor; a crystal end face electrode being out of contact with the grounded conductor and the high-voltage conductor; a Pockels cell transmitting light from the polarizer; an analyzer transmitting light reflected by the Pockels cell; a photodetector detecting light emitted from the analyzer; an intra-crystal electric field measurement unit converting voltage output by the photodetector into intra-crystal electric field; a bias electrode being out of contact with the crystal end face electrode; a bias supply; a bias supply control unit controlling the bias supply to keep internal electric field of the Pockels cell at zero; and a measurement voltage calculation unit obtaining voltage of the high-voltage conductor based on results output by the intra-crystal electric field measurement unit and the bias supply control unit.

A magneto-optic current transformer for measuring a current intensity of an electric current in an electrical conductor includes two light-guide units, each with an input polarizer, an output polarizer and a light guide arranged between the input and the output polarizer. A light-supply device is included which is configured to supply light to the light-guide units on the input side, and an analysis device which is configured to measure a luminous intensity of light output by the light-guide unit at the output side for each light-guide unit and to ascertain the current intensity of the electric current through the electrical conductor from the measured luminous intensities. A polarization axis of the output polarizer of each light-guide unit is rotated through a polarization angle in relation to a polarization axis of the input polarizer of the light-guide unit and the polarization angles of the two light-guide units differ from one another.

The present disclosure relates to the technical field of current sensors, and provides a fiber-optic current transformer based on nitrogen-vacancy (NV) centers in diamond, and a measurement method. The fiber-optic current transformer based on NV centers in diamond includes a device for laser light excitation and reflected light reception and analysis, a diamond NV center probe, a magnetic concentrator, and a microwave excitation device. The fiber-optic current transformer based on NV centers in diamond includes three measurement methods: an all-optical measurement method, a non-all-optical measurement method, and a measurement method combining the all-optical measurement method and the non-all-optical measurement method. A sensor in the present disclosure has advantages of a simple structure, strong practicability, resistance to external interference, and strong robustness.

A glass ring for current measurements includes a glass body, which can be disposed around an electrical conductor and has a light entry surface and a light exit surface. The glass ring allows light which enters the glass body through the light entry surface to circulate completely around the conductor in the glass body by reflection on external sides or outer faces of the glass body, the light exiting from the glass body on the light exit surface. The glass ring is formed of a monolithic glass body. A method for optical current measurement includes using a current flow in an electrical conductor to generate an electromagnetic field around the conductor, by which a polarization of a light beam in the glass ring around the conductor, in particular with a plane perpendicular to the longitudinal axis of the conductor, is changed as the light beam circulates around the conductor.

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.

An optical voltage sensor assembly includes an input fiber-optic collimator positioned and configured to collimate input light beam from a light source. A crystal material is positioned to receive the input light beam from the light source and configured to exhibit the Pockels effect when an electric field is applied through the crystal material. An output fiber-optic collimator is positioned to receive an output light beam from the crystal material and configured to focus the output light beam from the crystal onto a detector. Methods of using the optical voltage sensor assembly are also disclosed.