Abstract: It is proposed to use a spun birefringent fiber for a current sensor or magnetic field sensor. The fiber has a birefringence that increases with temperature. In this case, the temperature dependence of the fiber's sensitivity to magnetic fields counteracts the temperature dependence of the fiber's Verdet constant, which allows to design current and field sensors that have reduced temperature dependence.

Abstract: There is described an optical fiber cuing sensor having an opto-electronic module pan (10-2) for detecting an optical phase shift induced by the measurand field in a sensing fiber (12), a sensor head (10-1) including the sensing fiber (12), wherein the sensing fiber (12) is a spun highly-birefringent fiber having a length L=?ds defined by the line integral along the space curve given by the sensing fiber coil such that the length L of the sensing fiber (12) is sufficiently long to suppress thermal signal instabilities due to the spun character of the sensing fiber (12) while the effective number of fiber windings is low enough to maintain a maximum sensitivity over the full measurement range of the fiber-optical sensor (10).

Abstract: In a fiber-optic current sensor, a 22.5° Faraday rotator, which is part of the sensing fiber coil, determines the working point of the sensor. The coil is operated with substantially linearly polarized light or incoherent substantially left and right circularly polarized light waves. In one arrangement, a polarization beam splitter generates two optical signals that vary in anti-phase with changing current. A signal processor determines the current from the two anti-phase signals. Appropriately detuned and oriented fiber-optic half-wave or quarter-wave retarders before the fiber coil are used to reduce or cancel the adverse effects of temperature and bend-induced birefringence on the measurement signal. Moreover, the temperature may be derived from the difference in the bias of the anti-phase signals and may be used to cancel temperature effects in the signal processor.

Abstract: A fiber optic sensor and related method are described, with the sensor including a cross-coupling element in the optical path between a polarizing element and a sensing element, but separated from the sensing element itself; with the cross-coupling element generating a defined cross-coupling between the two orthogonal polarization states of the fundamental mode of a polarization maintaining fiber guiding light from the light source to the sensing element thus introducing a wavelength-dependent or temperature-dependent sensor signal shift to balance wavelength-dependent or temperature-dependent signal shifts due to other elements of the sensor, particularly signal shifts due to the wavelength dependence of the Faraday effect or the electro-optic effect constant.

Abstract: An interferometric sensor and related methods are provided, with a sensing element whereby a measurand induces a relative phase shift between two waves, at least one detector measuring an interference signal between the two waves, and further including a phase shift detection unit having as input the interference signal and determining a first measure representative of the principal value of the relative phase shift, and a contrast detection unit having as input the interference signal for determining a second measure representative of the cross-correlation between the two waves, and a further a processing unit for converting the first and second measures to a measurand value.

Abstract: A method of increasing accuracy of optical sensors based on generating two sets of light waves having different velocities in the presence of a non-vanishing measurand field within a sensing element of the sensor is described. A defined static bias phase shift is introduced between the two sets of light waves. The sensor converts a total optical phase shift including static bias optical phase shifts and measurand-induced optical phase shifts into anti-phase optical power changes in at least two detector channels. The method includes steps of normalizing the optical power changes after their conversion into electrical detector signals in the two detector channels to reduce effects of uneven intensity or power of the light source and different loss or gain in the detector channels. Further methods, sensors and apparatus for temperature stabilizing such optical sensors and novel sensors are also presented.

Abstract: A fiber-optic current sensor includes a measuring unit having a light source and a light detector, and a sensing head having a sensing fiber wound around a conductor and a retarder connected to the sensing fiber. The scale factor as a function of current of the fiber-optic current sensor is described by the product of two scaling functions fe? and fs? for the measuring unit and the sensing head, respectively. The data describing the scaling functions fe?, fs? is stored in a memory of the measuring unit, while the data describing the scaling function fs? is also stored in a memory of the sensing head. Providing two such memory devices allows to store the scaling functions fe? and fs? separately, thereby turning the control unit as well as the sensor head into easily replaceable modules.

Abstract: A voltage sensor includes an insulator with mutually insulated electrodes embedded therein. The electrodes are coaxial and cylindrical and overlap axially along part of their lengths. They are mutually staggered and control the surfaces of electric equipotential such that there is a substantially homogeneous electric field outside the insulator and a substantially homogeneous but higher field within a sensing cavity within the insulator. A field sensor is arranged within the sensing cavity to measure the field. This design allows for the production of compact voltage sensors for high voltage applications.

Abstract: A voltage sensor includes an insulator with mutually insulated electrodes embedded therein. The electrodes are coaxial and cylindrical and overlap axially along part of their lengths. They are mutually staggered and control the surfaces of electric equipotential such that there is a substantially homogeneous electric field outside the insulator and a substantially homogeneous but higher field within a sensing cavity within the insulator. A field sensor is arranged within the sensing cavity to locally measure the field. This design allows for the production of compact voltage sensors for high voltage applications.

Abstract: A fiber-optic current sensor uses a highly-birefringent spun fiber as sensing fiber. The light is fed through a retarder, which is a detuned quarter-wave or half-wave retarder. It is shown that such detuning can be used to compensate for temperature dependencies of the sensing head.

Abstract: In a fiber-optic current sensor, a 22.5° Faraday rotator, which is part of the sensing fiber coil, determines the working point of the sensor. The coil is operated with substantially linearly polarized light or incoherent substantially left and right circularly polarized light waves. In one arrangement, a polarization beam splitter generates two optical signals that vary in anti-phase with changing current. A signal processor determines the current from the two anti-phase signals. Appropriately detuned and oriented fiber-optic half-wave or quarter-wave retarders before the fiber coil are used to reduce or cancel the adverse effects of temperature and bend-induced birefringence on the measurement signal. Moreover, the temperature may be derived from the difference in the bias of the anti-phase signals and may be used to cancel temperature effects in the signal processor.

Abstract: A motor vehicle bodywork has a floor assembly with an upwardly convex and downwardly open longitudinal center tunnel and two side sills parallel thereto. Floor elements are disposed between the longitudinal center tunnel and the side sills. A driver side and a passenger side are each provided with at least one front and one rear seat crossmember, seen in the direction of travel. The seat cross-members extend in the transverse direction of the vehicle and rest on the associated floor elements. It is important that the driver side and/or passenger side seat cross-members are each connected to each other in their upper regions via a plate-like thrust element.

Abstract: DC current in a high voltage AC/DC or DC/AC converter station can be measured via the Faraday effect in one or more loops of an optical sensing fiber located at the base of a bushing extending through a wall of the hall. This arrangement can exploit the base of the bushing being at ground potential, which can simplify mounting work and maintenance.

Abstract: The current in a generator circuit breaker is measured using the Faraday effect of an optical sensing fiber looped around the breaker's conductor. The sensing fiber is arranged in a sensing strip, which can be mounted to the enclosure of the generator circuit breaker or to the conductor. Exemplary embodiments can have a wide measuring range and can easily be fitted to new or existing generator circuit breakers.

Abstract: A fiber optic current or magnetic field sensor uses a sensing fiber in a coil for measuring a current or a magnetic field and has a retarder for converting between linearly polarized light and elliptically polarized light. The retardation of the retarder, its temperature dependence as well as its azimuth angle in respect to the plane of the fiber coil are optimized in dependence of the birefringence in the sensing fiber in order to minimize the influence of temperature variations and manufacturing tolerances on the overall scale factor of the sensor.

Abstract: Two transversely poled fibers are disclosed which can be wound around a holder with their poling directions being anti-parallel. A coupling exchanges the polarization directions of the modes of the fibers. Thermally and mechanically caused birefringence changes can thereby be substantially cancelled, while electrical field induced birefringence changes can be added, to provide a more robust high voltage measuring device.

Abstract: A pressure sensor is disclosed with at least one pressure sensing element, the pressure induced changes in the optical properties of which are evaluated by illumination with at least one light source. The pressure sensor can include at least two semiconductor-based pressure sensing elements located in individual pressure chambers, which sensing elements are located essentially adjacent to each other. The sensing elements can be irradiated with the same light source, wherein the light transmitted through the sensing elements is detected using at least two corresponding detectors, and wherein the differential pressure in the two pressure chambers is evaluated based on the output of these detectors.

Abstract: A method is provided for tuning the fiber optic retarder of a fiber optic current sensor towards a desired temperature dependence, the sensing fiber is exposed to a magnetic field or corresponding electric current and the sensor signal as well as the signal's dependence on the retarder temperature are measured. From this initial sensor signal and its temperature dependence, a target sensor signal can be determined, at which the dependence on the retarder temperature equals a desired value. Then, the retarder is thermally treated until the sensor signal reaches the target value. The method obviates the need for repetitively measuring the temperature dependence during the tuning process.

Abstract: A fiber-optic current sensor includes a measuring unit having a light source and a light detector, and a sensing head having a sensing fiber wound around a conductor and a retarder connected to the sensing fiber. The scale factor as a function of current of the fiber-optic current sensor is described by the product of two scaling functions fe? and fs? for the measuring unit and the sensing head, respectively. The data describing the scaling functions fe?, fs? is stored in a memory of the measuring unit, while the data describing the scaling function fs? is also stored in a memory of the sensing head. Providing two such memory devices allows to store the scaling functions fe? and fs? separately, thereby turning the control unit as well as the sensor head into easily replaceable modules.

Abstract: An exemplary gas-insulated switchgear device is disclosed which includes a current sensor and a voltage sensor located at a partition insulator. The current sensor can include a magneto-optical fiber on a flexible carrier strip and can be manufactured separately for being easily mounted to an assembled switchgear device. The current sensor can include an electro-optical fiber extending radially into the partition insulator and whose ends are embedded in recesses in the bus bar as well as in the metal embracing of the partition insulator for accurately integrating the voltage.