Abstract: An arrangement is provided for measuring the field strength of a magnetic field, or measuring field, by an angle sensor. The angle sensor is aligned with the field lines of the measuring field at the position of the field strength of the measuring field, or measuring position. A device for generating a magnetic auxiliary field at the measuring position is also included. The angle sensor can be impressed with the magnetic auxiliary field in a predeterminable field strength and in a direction deviating from that of the field lines of the measuring field at the measuring position, forming a resultant magnetic field with a field line direction. The field line direction is measured by the angle sensor as a measure of the field strength of the measuring field. The arrangement is reliable, suitable for measuring high magnetic field strengths, has no reactive effects, and permits measurements with magnetoresistive angle sensors.

Abstract: An inductive measuring transducer having bodies movable relative to one another, one of the bodies being a sensor component including an inductive sensor that produces an alternating magnetic field. Another of the bodies is a pickup component including an inductive pickup into which the alternating magnetic field is injected. The pickup component includes a conductor loop in which the inductive sensor induces a voltage. A voltage curve independent of position of the sensor component relative to the pickup component develops over the conductor loop. Resistors have first ends connected along the coductor loop and second ends connected together in groups at connection points. Voltage can be picked off from the connection points that correspond to functions of the position of the sensor component relative to the pickup component and permit the position to be clearly determined, the position and value of the resistors defining the functions of the position.

Abstract: A position sensor for sensing linear or radial position, including at least four magnets, a first ferrous plate having at least two of the at least four magnets located at spaced locations along the first ferrous plate, the at least two magnets being oriented such that a north pole of at least one of the at least two magnets is directed toward the first ferrous plate and a south pole of an other of the at least two magnets is directed toward the first ferrous plate, a second ferrous plate having at least two of the at least four magnets located at spaced locations along the second ferrous plate, the at least two magnets being oriented such that a north pole of at least one of the at least two magnets is directed toward the second ferrous plate and a south pole of an other the at least two magnets is directed toward the second ferrous plate, the first ferrous plate and the second ferrous plate being generally parallel and spaced apart and at least one magnetic flux responsive device disposed between the first

Abstract: An electro-optical modulator and a method for biasing a Mach-Zehnder modulator. The inventive modulator includes a layer of material at least partially transparent to electromagnetic energy. A first conductive layer is disposed on a first surface of the layer of at least partially transparent material. A second conductive layer is disposed on a second surface of the layer of at least partially transparent material. A layer of insulating material is disposed on the second conductive layer and a third conductive layer is disposed on the layer of insulating material. In the illustrative application, the modulator is a Mach-Zehnder modulator. A biasing potential is applied to the second conductive layer of the modulator and a modulating voltage is applied across the first and the third conductive layers.

Abstract: This method consists in supplying at least a first alternating signal, at a determined frequency, to one end of a stator coil and recuperating a measurement signal at a second end of said coil, said measurement signal being provided to electronic processing means, which are arranged to extract data relating to a periodic variation of the effective inductance of the stator coil. This variation is a function of the angular position of the rotor. By alternately carrying out such a measurement on the stator coils, three periodic curves can be extracted (SPCA, SPCB, SPCC) defining a zigzag curve (70) allowing the angular position of the rotor to be determined.

Abstract: A non-contacting magnetic position sensor that produces a magnetic field having improved linear characteristics over an extended sensing range. The magnetic position sensor includes a pair of magnets, a pair of pole pieces extending between the magnets and spaced apart to define an air gap, and a magnetic flux sensor operable to sense varying magnitudes of magnetic flux density along the length of the air gap. The pole piece segments form a stepped interface with each of the magnets and cooperate with the magnets to provide a magnetic field having a magnetic flux density that varies in a substantially linear manner along substantially the entire length of the air gap. The magnetic flux sensor is positioned within the magnetic field and is operable to sense a magnitude of the varying magnetic flux density along the air gap and to provide an output signal representative of a position of the magnetic flux sensor relative to the magnetic field.

Abstract: A magneto-resistive device with built-in test structure. The magneto-resistive device includes a slider having first and second lower termination pads and first and second upper termination pads. A first conductive trace element electrically couples the first lower termination pad to the first upper termination pad and a second conductive trace element electrically couples the second lower termination pad to said second upper termination pad. The magneto-resistive device also includes a magneto-resistive transducer deposited on the slider and the resistance of the magneto-resistive transducer is obtained by passing an electrical current between the first and second lower termination pads and measuring a voltage across the first and second upper termination pads.

Abstract: An electric current comprising a plurality of harmonic components is passed through the pipe under test, a magnetic field produced by it outside the pipe is measured, a spectrum of the electric current is measured, a spectrum from measured magnetic field data is also obtained. The ratios between identical spectral components of the current and magnetic field are evaluated. The test apparatus comprises a current source supplying an electric current, a means for measuring and storing momentary current values, a means for evaluating a current spectrum to define harmonic components of the electric current, at least one magnetic field sensor for measuring and storing momentary values of the magnetic field produced outside the pipe by the current, a means for evaluating the magnetic field spectrum to define harmonic components of the magnetic field, and a means for comparing and analyzing the obtained spectral data of the current and magnetic field.

Abstract: A method and a device for detecting mispolarization in a signal transducer is described, with which the output signal of the signal transducer—that has at least one singularity—is converted into a square-wave signal. Intervals between specifiable signal-level changes are monitored in the region of the singularity, or plausibility windows are set, within which specifiable events must occur. If the intervals do not correspond to the expected intervals, or if specifiable events do not occur within the specifiable time windows or plausibility windows, mispolarization is detected. The method for detecting mispolarization is used, for example, in the case of a signal transducer having a plurality of uniform angular points and one reference point, but it is not limited to such transducers.

Abstract: A method which compensates errors resulting from offset voltages and external magnetic fields when a magnetic sensor is used to measure coating thickness. The method also allows compensation of a temperature dependent change for output voltages of the magnetic sensor.

Abstract: A scale loop formed by a loop trace of electrically conductive material is usable in an induced current position transducer. The scale loop is continuous and has a particular shape depending on the configuration of the induced current position transducer. The scale loop is not in contact with other highly conductive materials. The dimensions of the cross-section of the conducting trace are chosen to increase the transfer of energy through the transducer.

Abstract: A method and apparatus for detecting ferrous changes passing axially through a cylindrical space. In one embodiment, the method comprises surrounding the cylindrical space with a nonmagnetic cylinder having an outer wall and a cylindrical axis; creating an alternating magnetic field in the cylindrical space, the magnetic field created by a rotatable permanent magnet; monitoring the magnetic field with magnetic flux sensors placed outside the outer walls; and detecting changes in the magnetic field as ferrous matter passes axially through the cylindrical space. In other embodiments, the apparatus identifies ferrous changes as the tool joints that connect a jointed tubing string as the tubing string is moved in or out of a well bore, or as the presence or absence of a coiled tubing string in the well bore.

Abstract: A device and method for compensating for chromatic dispersion in an optical signal. The optical signal is coupled between an optical waveguide of a type having (i) a fundamental-mode waveguide and (ii) a higher-order mode waveguide surrounding the fundamental-mode waveguide, wherein different effective indexes of refraction are associated with the fundamental-mode and higher-order mode waveguides. The device comprises a transmissive, long-period optical grating disposed along a length of the optical waveguide and has a receiving end and a transmitting end. The grating is chirped between the ends along a light conducting axis of the optical waveguide such that different wavelengths of the optical signal are coupled to the fundamental-mode and higher order mode waveguides at different points along the length of the grating so that chromatic dispersion is corrected at the transmitting end.

Abstract: A method and system for measuring anchoring strength of liquid crystal through measurement of magnetic field induced torque. In the system for measuring anchoring strength of liquid crystal, when a magnetic field (7) is applied to a liquid crystal cell (1), a torsion wire (5) twists in response to the magnetic field (7) As a result, a mirror (6) attached to the torsion wire (5) displaces, and thus a laser beam emitted from a laser (8) and reflected from the mirror (6) rotates. The displacement of the laser beam is detected by a bisected photodiode (9) for position detection. Specifically, outputs from the bisected photodiode (9) are amplified by means of amplifiers (10) and (11), which output voltages VA and VB, respectively. The magnetic-field induced torque is proportional to the rotational angle of the mirror, which is proportional to VA-VB.

Abstract: A tunable magnetic device which includes a permanent magnet in the shape of a ring, an inner aperture, a tuning member, and a field sensor secured to the permanent magnet. The tuning member may be a ferrous or magnetic material and may be secured to a non-magnetic tuning device. The inner aperture is preferably small compared to the permanent magnet. The magnetic device provides a magnetic field that is sensitive to the proximity of a ferrous object and provides a tunable mechanism to locally balance the magnetic field where the field sensor is located.

Abstract: For measurement of a liquid level, an optical fiber connected at its one end portion to force receiving means movably arranged in liquid to receive force from the liquid is dipped in the liquid together with the force receiving means, and a change in the force acting on said force receiving means when the liquid level changes is detected as a change in strain in the optical fiber by means of an optical fiber strain gauge connected to the other end of the optical fiber, thus measuring a water level of the liquid.

Abstract: A method and apparatus for processing an optical signal in an optical waveguide using a closed loop wavelength dependent active tuning system. A tunable fiber Bragg grating, optical processor and a controller provide feedback control of the central wavelength of the tunable fiber Bragg grating. Changes in wavelength of the processed signal are followed to keep the tunable fiber Bragg grating tuned to a peak wavelength for maximum sensitivity.

Abstract: An apparatus and associated testing method for identifying void heads in magnetic storage systems in which a first bit error rate is determined using data written at a first overshoot amount. A second bit error rate is determined using data written at a second rate current in a second overshoot amount. A physically damaged transducer head is identified based upon a comparison of the first bit error rate to the second bit error rate.

Abstract: A light path deviation detecting apparatus has a diverging element for diverging a detection target light path into two light paths, and detects light receiving position on light receiving surfaces disposed spaced light path lengths different from each other in the diverged light paths. A tilt of the detection target light path is detected from the light receiving positions detected respectively.

Abstract: A sensor for detecting defects in a component includes an electric coil fed with a varying electrical current to create a varying magnetic field penetrating at least partly into the component under test, and a defect detector including a magnetoresistor. The above components are accommodated in a protective housing having a detection face disposed near and parallel to a surface of the component under test. The coil has its axis &Dgr; perpendicular to the detection face and the magnetoresistor is in the vicinity of the detection face. The magnetoresistor is a giant magnetoresistor and is disposed so that its sensitivity axis &Dgr;1 sensitive to variations in a magnetic field is parallel to the detection face of the housing.