Abstract: A method and device for estimating a density value ?m indicative of a true density ? or for estimating a viscosity value ?m indicative of a true viscosity ? of a fluid is disclosed. For this, a first resonance frequency fR of a first mechanical oscillator in a reference volume and a second resonance frequency fF of a second mechanical oscillator in contact with the fluid are measured. The estimated value ?m or ?m is then derived using these resonance frequencies fR and fF. During this derivation, at least one fluid-temperature- or fluid-pressure-dependent parameter of the fluid is used. Additionally or alternatively, the first (i.e. reference) mechanical oscillator is arranged in contact with a reference fluid. Thus, fundamental errors in the derivation of the estimated value ?m or ?m are reduced and the estimated value becomes more reliable.

Abstract: A method and device for estimating a density value ?m indicative of a true density ? or for estimating a viscosity value ?m indicative of a true viscosity ? of a fluid is disclosed. For this, a first resonance frequency fR of a first mechanical oscillator in a reference volume and a second resonance frequency fF of a second mechanical oscillator in contact with the fluid are measured. The estimated value ?m or ?m is then derived using these resonance frequencies fR and fF. During this derivation, at least one fluid-temperature- or fluid-pressure-dependent parameter of the fluid is used. Additionally or alternatively, the first (i.e. reference) mechanical oscillator is arranged in contact with a reference fluid. Thus, fundamental errors in the derivation of the estimated value ?m or ?m are reduced and the estimated value becomes more reliable.

Abstract: An electro-optical high-voltage sensor includes a waveguiding sensing fiber of an electro-optical material. The electrical field of the voltage to be measured is substantially parallel to the longitudinal axis of the sensing fiber. The sensing fiber carries two orthogonally polarized light waves, with the applied field affecting the birefringence between the waves. Using an electro-optical waveguiding fiber in this configuration allows the voltage between two widely spaced points to be accurately measured.

Abstract: The current in a conductor is measured by exploiting the Faraday effect in a sensing fiber. The light returning from the sensing fiber is split into at least two parts, at least one of which is analyzed by a first circular analyzer for generating a first signal. A second part may e.g. be analyzed by a second circular analyzer, and a third part may be analyzed by a linear analyzer. By combining the signals obtained in this way, the current induced phase delay in the returning light can be measured efficiently and accurately.

Abstract: An electro-optical high-voltage sensor includes a waveguiding sensing fiber of an electro-optical material. The electrical field of the voltage to be measured is substantially parallel to the longitudinal axis of the sensing fiber. The sensing fiber carries two orthogonally polarized light waves, with the applied field affecting the birefringence between the waves. Using an electro-optical waveguiding fiber in this configuration allows the voltage between two widely spaced points to be accurately measured.

Abstract: The current in a conductor is measured by exploiting the Faraday effect in a sensing fiber. The light returning from the sensing fiber is split into at least two parts, at least one of which is analyzed by a first circular analyzer for generating a first signal. A second part may e.g. be analyzed by a second circular analyzer, and a third part may be analyzed by a linear analyzer. By combining the signals obtained in this way, the current induced phase delay in the returning light can be measured efficiently and accurately.

Abstract: A high-voltage component, having a first end and a second end, whereby the first end is on a high-voltage potential with respect to the second end. An insulating part, is arranged between the first end and the second end, and an optical fiber is integrated in the high-voltage component and extends from the first end to the second end. A capillary extends from the first end to the second end and is arranged within the insulating part. The inside diameter of the capillary exceeds the outside diameter of the fiber, and the fiber is arranged within the capillary. The capillary includes a protective medium to achieve a dielectric strength in the capillary, which dielectric strength is suitable for the operating conditions.

Abstract: The fiber-optic sensor head (2) for a current or magnetic field sensor comprises an optical fiber which contains a magnetooptically active sensor fiber (3) and at least one polarization-maintaining supply fiber (5), which are optically connected, with the sensor fiber (3) having its fiber protective sheath removed. The sensor head (2) furthermore contains a capillary (6), in which at least the sensor fiber (3) is arranged. Furthermore, the sensor head (2) can be bent in the area of the sensor fiber (3), and a friction reducing means (7) is provided in the capillary (6), in order to reduce the friction between the sensor fiber (3) and the capillary (6). The friction reducing means (7) is advantageously an oil or a dry lubricating means (7). The capillary (6) is advantageously encased by a capillary casing (8). The sensor (2) allows very largely temperature-dependent measurements, is easy to install and allows measurements on large cross-section conductors.

Abstract: A high-resolution fiber laser sensor for measuring a quantity to be measured M has a pumping light source, a fiber laser and a detection/evaluating unit. The fiber laser has: a birefringent first end reflector, a second end reflector, a laser-amplifying fiber, a sensor fiber and a mode coupling. The laser-amplifying fiber, the sensor fiber and the mode coupling are arranged between the end reflectors. In the fiber laser, light is capable of propagating in two optical states which are orthogonal to one another due to their polarization and/or their transversal space structure. The orthogonal optical states can be coupled to one another by the mode coupling. In the fiber laser, a number of longitudinal modes are capable of oscillating in each of the two optical states. In the sensor fiber a change in the birefringence for the two orthogonal optical states can be achieved by interaction of the quantity to be measured with the sensor fiber.

Abstract: A fiber-optic sensor head is disclosed for an optical current or magnetic-field sensor which can have an optical fiber which includes a magnetooptically active sensor fiber which is optically connected to at least one polarization-defining element. The sensor fiber can be arranged in a magnetic field to be measured or around a conductor carrying current to be measured and can be in the form of a coil, with the coil defining a coil plane (A) with a surface normal (Ns), and with the at least one polarization-defining element having a marked axis (f). The sensor head can be flexible in the area of the sensor fiber, and an adjustment means can be provided for adjustment of a predeterminable angle ? between the marked axis,(f) and the surface normal (Ns) or for adjustment of predeterminable angles ?, ?? between the marked axes (f) and the surface normal (Ns).

Abstract: A high-voltage component, having a first end and a second end, whereby the first end is on a high-voltage potential with respect to the second end. An insulating part, is arranged between the first end and the second end, and an optical fiber is integrated in the high-voltage component and extends from the first end to the second end. A capillary extends from the first end to the second end and is arranged within the insulating part. The inside diameter of the capillary exceeds the outside diameter of the fiber, and the fiber is arranged within the capillary. The capillary includes a protective medium to achieve a dielectric strength in the capillary, which dielectric strength is suitable for the operating conditions.

Abstract: The invention relates to a fiberoptic current or magnetic field sensor having a plurality of sensor heads, and to a corresponding measurement method. The sensor has a light source: N?2 sensor heads; at least one phase modulation unit; a detector; a control and evaluation unit. The at least one phase modulation unit is connected to at least one of the sensor heads. Lightwaves can be differentially phase-modulated in a non-reciprocal fashion by means of the at least one phase modulation unit. Modulation amplitudes ?0,n and modulation frequencies vn are selected as a function of modulation-relevant optical path lengths ln.

Abstract: A high-resolution fiber laser sensor for measuring a quantity to be measured M has a pumping light source (2), a fiber laser (1) and a detection/evaluating unit (3). The fiber laser (1) has: a birefringent first end reflector (11), a second end reflector (12), a laser-amplifying fiber (13), a sensor fiber (14) and a means for mode coupling (15). The laser-amplifying fiber (13), the sensor fiber (14) and the means for mode coupling (15) are arranged between the end reflectors (11, 12). In the fiber laser (1), light is capable of propagating in two optical states (x, y; LP?01, LP?11) which are orthogonal to one another due to their polarization and/or their transversal space structure. The orthogonal optical states (x, y; LP?01, LP?11) can be coupled to one another by the means for mode coupling (15). In the fiber laser (1), a number of longitudinal modes (LMxp, LMxp+1 . . . , LMyq, LMyq+1 . . . ; LM01p, LM01p+1 . . . , LM11q, LM11q+1 . . .

Abstract: The fiber-optic sensor head (2) for a current or magnetic field sensor comprises an optical fiber which contains a magnetooptically active sensor fiber (3) and at least one polarization-maintaining supply fiber (5), which are optically connected, with the sensor fiber (3) having its fiber protective sheath removed. The sensor head (2) furthermore contains a capillary (6), in which at least the sensor fiber (3) is arranged. Furthermore, the sensor head (2) can be bent in the area of the sensor fiber (3), and a friction reducing means (7) is provided in the capillary (6), in order to reduce the friction between the sensor fiber (3) and the capillary (6). The friction reducing means (7) is advantageously an oil or a dry lubricating means (7). The capillary (6) is advantageously encased by a capillary casing (8). The sensor (2) allows very largely temperature-dependent measurements, is easy to install and allows measurements on large cross-section conductors.

Abstract: The electra-optical voltage sensor has an electra-optically active medium and a distance medium between two electrodes, between which the voltage V to be measured is present. The media and the thicknesses d1, d2 of the media are chosen in such a way that the measured voltage signal has no temperature dependence. By way of example, the thicknesses d1, d2 are chosen in such a way that the influence of the temperature dependences of critical electra-optical coefficients and dielectric constants of the media on the voltage signal cancel one another out. The two media are advantageously arranged in the form of a rod, comprising an alternating arrangement of cylindrical elements of the two media, between the electrodes. BGO and fused silica may advantageously be used as media. The sensor is preferably cast in silicone.

Abstract: The voltage sensor for measurement of a voltage V, which is present between two electrodes (3, 4) and generates an electric field E, comprises at least two layers (1a, 2a) made of electro-optically active material and being arranged along a light path (5). Through the layers there passes a light beam, the phase and/or state of polarization of which is influenced on account of the electro-optical effect. The orientation of the electro-optically active layers (1a, 2a) relative to the light path and the electric field E is chosen in such a way, that the influencing of the light (5) in the second layer (2a) counteracts the influencing of the light (5) in the first layer (1a). In this way, it is possible to realize a sensor with a high half wave voltage, so that high voltages V can be measured unambiguously. A plurality of first and second electro-optically active layers are advantageously arranged between the electrodes (3, 4).

Abstract: The electro-optical voltage sensor has an electro-optically active medium and a distance medium between two electrodes, between which the voltage V to be measured is present. The media and the thicknesses d1, d2 of the media are chosen in such a way that the measured voltage signal has no temperature dependence. By way of example, the thicknesses d1, d2 are chosen in such a way that the influence of the temperature dependences of critical electro-optical coefficients and dielectric constants of the media on the voltage signal cancel one another out. The two media are advantageously arranged in the form of a rod, comprising an alternating arrangement of cylindrical elements of the two media, between the electrodes. BGO and fused silica may advantageously be used as media. The sensor is preferably cast in silicone.

Abstract: The voltage sensor for measurement of a voltage V, which is present between two electrodes (3, 4) and generates an electric field E, comprises at least two layers (1a, 2a) made of electro-optically active material and being arranged along a light path (5). Through the layers there passes a light beam, the phase and/or state of polarization of which is influenced on account of the electro-optical effect. The orientation of the electro-optically active layers (1a, 2a) relative to the light path and the electric field E is chosen in such a way, that the influencing of the light (5) in the second layer (2a) counteracts the influencing of the light (5) in the first layer (1a). In this way, it is possible to realize a sensor with a high half wave voltage, so that high voltages V can be measured unambiguously. A plurality of first and second electro-optically active layers are advantageously arranged between the electrodes (3, 4).

Abstract: The invention relates to a fiberoptic current or magnetic field sensor having a plurality of sensor heads (H), and to a corresponding measurement method. The sensor has: a light source (1); N≧2 sensor heads (H); at least one phase modulation unit (PME) having at least one phase modulator (PM); a detector (2); a control and evaluation unit (5). The at least one phase modulation unit (PME) is optically connected to at least one of the sensor heads (H). Linearly polarized lightwaves can be differentially phase-modulated in a non-reciprocal fashion by means of the at least one phase modulation unit (PME).

Abstract: The subject matter of the present invention is a fiber Bragg grating sensor 1, 25 which is suitable, in particular, for measuring differential pressures and flow rates v1 in oil drill holes. The sensor principle according to the invention is based on using a transducer 1 with two pressure chambers 7a, 7b to convert a hydrostatic pressure difference between two liquid or gaseous media 11a, 11b into a longitudinal fiber elongation or fiber compression and measuring it via the displacement of the Bragg wavelength &Dgr;&lgr;B of at least one fiber Bragg grating 3, 4. Exemplary embodiments are specified which have two fiber Bragg gratings 3, 4 which are sensitive to elongation in opposite senses and which have temperature-compensating transducers 1, and which have a plurality of transducers 1 in a wavelength-division-multiplexing configuration. One embodiment relates to measuring a flow rate v1 with the aid of a venturi tube 23.