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.

Abstract: The invention relates to a DFB fiber laser sensor (1). A measurement quantity makes it possible to induce a linear birefringence between mode pairs of the laser-amplifying fiber (2) and to measure an associated beat frequency (&Dgr;&ngr;1, &Dgr;&ngr;2, &Dgr;&ngr;3). According to the invention, the laser-amplifying fiber (2) has a nonrotationally symmetrical structure, so that it is possible to detect isotropic pressures p, acoustic waves or chemical substances that can be added radially to the laser-amplifying fiber (2). In a second aspect of the invention, an emission wavelength range and parameters (a, b, &Dgr;N) of the laser-amplifying fiber (2) and also a grating period L of the fiber Bragg grating resonator (3) are coordinated with one another such that at least two different spatial modes (LP01, LP11even, LP11odd, LP21even) are propagatable and it is possible to measure beat frequencies (&Dgr;&ngr;1, &Dgr;&ngr;2, &Dgr;&ngr;3) between oscillatory longitudinal laser modes assigned to them.

Abstract: In order to measure an electrical voltage in an electrooptical voltage converter, polarized light at two wavelengths is sent through the medium (1). On the output side, the light is passed through a polarizer (10) and the remaining signal is measured. In order to compensate for the temperature dependency of the electrooptical coefficients, the measurement results at the two wavelengths are compared with one another, and that voltage value which is consistent with both measurements is used.

Abstract: In a fiber optic current sensor having a coiled sensor fiber (1) which encloses a current conductor (S), and at least one phase delay element (4, 5) adjoining the sensor fiber (1), the at least one phase delay element (4, 5) has a phase delay with a temperature dependence such that it at least approximately compensates for a temperature dependence of a Verdet's constant (V) of the sensor fiber (1). It is thereby possible to achieve an at least approximately temperature-independent sensor signal.

Abstract: A fiber-optic current sensor has a reflection interferometer having a fiber-optic supply lead and a coil-shaped optical sensor fiber, the sensor fiber being connected with a first end to the fiber-optic supply lead, and being provided at a second, free end with a reflector. The fiber-optic supply lead has two fiber arms, which interconnect a detector-side and a sensor-side polarization-maintaining coupler. A phase modulator for modulating differential phases of two polarized waves propagating in the supply lead fiber is arranged in one of these two fiber arms, in which it modulates the differential phase of two waves polarized parallel to one another. Moreover, the sensor can change the direction of polarization in one of the two fiber arms, such that optical waves with orthogonally linear polarizations propagate in a segment of the supply lead fiber adjoining the sensor-side coupler. As a result, the advantages of the reflection interferometer can be combined with those of a Sagnac interferometer.

Abstract: The invention relates to a frequency-coded fiber laser pressure sensor (1) which is especially suitable for measuring isotropic pressures in oil wells. The sensor principle provided for in the invention is based on the fact that in a fiber laser (2) doped with Er3+ a monomode or bimodal sensor fiber (5, 5a, 5b) is positioned whose pressure-related birefraction results in a frequency shift and beat frequencies between the orthogonal linear polarisation modes x, y or the spatial modes LP01 and LP11straight line. The beat frequencies are easily measured using a frequency counter (19). Temperature-related variations in birefraction are compensated in a differential arrangement of two sensor fiber segments (5a, 5b). Fiber-integrated Bragg gratings (4a, 4b) with low bandwidths (0.2 nm) are especially suitable as laser end reflectors.

Abstract: A method is described for producing a fiberoptic waveguide with a basic segment (11) and a phase shift segment (12), the basic segment (11) and phase shift segment (12) having fiber cores (K) of the same form and the fiber cores being aligned at a defined angle (&agr;) to one another. In the method, use is made of an optical fiber (1) having a fiber core (K) of the abovenamed form, which fiber is twisted at least approximately by the abovenamed defined angle (&agr;) and held fixed in this torsional position. Subsequently, a stress-relief zone (13) is heated inside the twisted fiber (1) until the torsion is released inside the stress-relief zone (13) and the basic segment (11) is produced on one side of the stress-relief zone (13) and the phase shift segment (12) is produced on the other side. In this case, the fixing of the torsional position is maintained until after solidification of the stress-relief zone (13).

Abstract: A pole of a high- and/or medium-voltage circuit breaker, including an insulating housing, at least one, interruption chamber which is positioned inside the insulating housing and contains at least a moving contact and at least a fixed contact. A device for measuring the electric current flowing through the pole, and a dielectric gas, the particularity of which is the fact that said device for measuring the electric current flowing through the pole includes an optical current sensor arranged within a volume of the pole that is occupied by the dielectric gas.

Abstract: The present invention relates to a fiber laser pressure sensor 1 which is suitable in particular for measuring differential pressures and flow velocities v1 in oil boreholes. The fiber laser 2 according to the invention comprises two sensor fiber segments 5a, 5b subjected to different pressure loading, in which segments a birefringence proportional to the differential pressure &Dgr;p=p1−p2, and consequently a beat frequency, is induced between the polarization modes or spatial modes in the fiber laser 2. Exemplary embodiments with polarimetric monomode fibers 5a, 5b and/or with elliptical two-mode fibers 5a, 5b are specified. Furthermore, pressure-resistant multichamber sensor housings 25 and wavelength division multiplex arrangements are disclosed for the fiber laser pressure sensor 1. One advantage is that the pressure signal is wavelength-coded and thus highly insensitive to interference.

Abstract: The subject-matter of the present invention is a wavelength-coded fiber Bragg grating pressure sensor 1 which is suitable, in particular, for use in the case of high pressures and temperatures in oil drill holes. The sensor principle according to the invention is based on the fact that the hydrostatic pressure of a liquid or gaseous medium 11 is converted with the aid of a transducer 1 into a longitudinal fiber elongation or fiber compression. The transducer 1 comprises a measuring or pressure cylinder 7a which exchanges pressure with the medium 11, and a reference cylinder 7b which is shielded from the medium 11 or oppositely pressure-loaded. Temperature-compensated transducers 1 with a temperature-independent Bragg wavelength &lgr;B can be realized by introducing a suitable temperature dependence of the mechanical prestressing of the pressure sensor fiber 3 by selecting the materials, lengths and arrangements of the fiber holder supports 5a, 5b.

Abstract: A fiber-optic current sensor has a reflection interferometer having a fiber-optic supply lead (2) and a coil-shaped optical sensor fiber (1), the sensor fiber (1) being connected with a first end to the fiber-optic supply lead (2), and being provided at a second, free end with a reflector (10). The fiber-optic supply lead (2) has two fiber arms (20, 21), which interconnect a detector-side and a sensor-side polarization-maintaining coupler (7, 8). A phase modulator (9) for modulating differential phases of two polarized waves propagating in the supply lead fiber (2) is arranged in one of these two fiber arms (20, 21), in which it modulates the differential phase of two waves polarized parallel to one another. Moreover, a means for changing the direction (80) of polarization is present in one of the two fiber arms (20), such that optical waves with orthogonally linear polarizations propagate in a segment (22) of the supply lead fiber (2) adjoining the sensor-side coupler (8).

Abstract: In a fiber optic current sensor having a coiled sensor fiber (1) which encloses a current conductor (S), and at least one phase delay element (4, 5) adjoining the sensor fiber (1), the at least one phase delay element (4, 5) has a phase delay with a temperature dependence such that it at least approximately compensates for a temperature dependence of a Verdet's constant (V)of the sensor fiber (1). It is thereby possible to achieve an at least approximately temperature-independent sensor signal.

Abstract: A method is described for producing a fiberoptic waveguide with a basic segment (11) and a phase shift segment (12), the basic segment (11) and phase shift segment (12) having fiber cores (K) of the same form and the fiber cores being aligned at a defined angle (&agr;) to one another. In the method, use is made of an optical fiber (1) having a fiber core (K) of the abovenamed form, which fiber is twisted at least approximately by the abovenamed defined angle (&agr;) and held fixed in this torsional position. Subsequently, a stress-relief zone (13) is heated inside the twisted fiber (1) until the torsion is released inside the stress-relief zone (13) and the basic segment (11) is produced on one side of the stress-relief zone (13) and the phase shift segment (12) is produced on the other side. In this case, the fixing of the torsional position is maintained until after solidification of the stress-relief zone (13).

Abstract: The subject matter of the present invention is a fiber-optic outdoor high-voltage sensor 1. The known sensor principle is based on the fact that a piezoelectric quartz cylinder 3 wound with a glass fiber 4a effects a voltage-proportional fiber strain which is measured interferometrically. According to the invention, a 420 kV outdoor sensor 1 is created by virtue of the fact that several quartz cylinders 3 and electrically conductive spacing elements 5 are arranged in an alternating fashion one behind another and are sealed in a silicone-shielded 17 insulating tube 16 by means of polyurethane 18 or silicone 21. Dividing the high voltage between several spaced, E-field integrating sensor elements 2 permits simple field control and a very high measuring accuracy. In addition, the fiber-optic voltage sensor 1 is distinguished by a low outlay on insulation, compactness and low weight, and can easily be scaled to other voltage levels and be effectively combined with optical current sensors 38.

Abstract: Without special measures, a fiber-optic current sensor coil (11) and fiber-optic .lambda./4 time delay elements (9, 9'), which are connected in series with the current sensor coil (11), are temperature-dependent with respect to a relative phase lag of light passing through. In order to avoid a temperature correction or temperature compensation, the current sensor coils (11) and, if appropriate, also the .lambda./4 time delay elements (9, 9') are annealed, so that virtually no mechanical stresses remain in the optical fibers. The current sensor coil (11) is preferably mounted unrestrained in a capillary (20) filled with a protective gas. The capillary (20) is embedded in a gastight fashion in a potting compound (22) made from polyurethane, and is thus also mechanically protected.

Abstract: The piezoelectric effect of an optical sensor (6) made from quartz is a function of temperature. Without correcting or compensating measures, this temperature dependence leads to a falsification of the measuring signal if the temperature of the sensor element is not held constant. In order to obtain accurate measurements for variable sensor temperatures T.sub.s, a temperature-corrected measuring signal M is provided in accordance with:M=U13.multidot.(1+.alpha..multidot.(T.sub.0 -T.sub.s)),U13 signifying a control signal, T.sub.0 a prescribable calibration temperature of the sensor (6), and .alpha. the temperature coefficient of the sensor (6). In this case, the sensor temperature (T.sub.s) is calculated in accordance with:T.sub.s =f(K,E(U.sub.Tr)),K being a contrast parameter which is calculated from light power signals (U1, U2), is a function of the sensor temperature (T.sub.s) and is proportional to the interference contrast, and U.sub.Tr signifying a signal receiver temperature signal and T.sub.

Abstract: In order to detect, in particular, a high electric voltage (8), use is made of an electrooptic sensor with an electrooptic crystal (4) such as is applied in Pockels cells. Light is irradiated into the electrooptic crystal (4) in a linearly polarized fashion from a light source (L) via a fiber coupler (FK), a fiber-optic cable (F1), a collimator (K1), a 1st polarizer (P1), a beam splitter (1), and 1st and 2nd glass plates (2, 3). Located at the end face of said crystal is a 3rd glass plate (5) having a layer electrode (6) which simultaneously acts as a mirror (7) and retroreflects the incident light through the electrooptic crystal (4). One component beam (T1) of the reflected light passes back to a 1st light detector (D1) via the beam splitter (1) and the 1st polarizer (P1), now acting as an analyzer. A 2nd component beam (T2) passes to a 2nd light detector (D2) via a .lambda./4-delay plate (9), a 2nd polarizer (P2), a 90.degree. prism (10), a collimator (K2) and a 2nd fiber-optic cable (F2).

Abstract: In a fiber-optic sensor for measuring electric fields and voltages, in place of a double-mode fiber extending between sensor head (15) and evaluating unit (14) two separate, similar double-mode fibers (5a, 5b) are connected in series in the manner of a tandem interferometer. The first double-mode fiber (5a), serving as sensor fiber, is operated in reflection geometry. Together with the sensor element (6), it is disposed in the sensor head (15). The second double-mode fiber (5b), serving as reference fiber, is situated within the separate evaluating unit (14). Within the latter there is also provided at least one fiber coupler or beam splitter, which is required on account of the operation of the sensor fiber in reflection geometry. Sensor head (15) and evaluating unit (14) are connected by a single insensitive monomode fiber.

Abstract: In a fiber optic sensor for measuring electric fields and voltages, in place of a bimode fiber extending between sensor head (14) and evaluation unit (13) two separate bimode fibers (4a, 4b) of the same type are connected in series in the manner of a tandem interferometer. The first bimode fiber (4a) is disposed, together with the sensor element (6), in the sensor head (14). The second bimode fiber (4b) is situated within the separate evaluation unit (13). In this way, the sensor head (14) and the evaluation unit (13) are connected only by insensitive monomode fibers (2a, 2b).

Abstract: In a fiber-optic sensor for alternating electric fields or voltages, the interference in a bimodal fiber (3) is measured passively. To this end, the mutually phase-shifted near-field and remote-field signals are separated by optical means (15) at the exit end of the bimodal fiber (3), and passed to appropriate detectors (17a, b, c), and the electrical signals created are evaluated by electronic means (18).