Abstract: An add-drop filter, utilizing chiral elements, that enables a new signal to be added at a particular vacuum wavelength &lgr;′k to a fiber optic line carrying n signal channels over a band of wavelengths encompassing &lgr;1 . . . &lgr;k−1, &lgr;k, &lgr;k+1 . . . &lgr;n, while an existing signal, &lgr;k, is simultaneously dropped from the signal group.

Abstract: The present invention provides for an apparatus and method to manufacture optical fiber in a way that produces controlled and patterned diffusion of optical radiation along its length. The novelty of the described invention is that the patterns of diffusion are produced at the time the optical fiber is manufactured. The “in-line” manufacturing method avoids the need for post-production treatment of the fiber, which makes the process highly efficient and economical. Light diffusing optical fibers of significant length can be produced. Several manufacturing configurations to achieve the desired effects and their inclusion in the fiber production process are described. The processes can be configured to process optical fibers constructed from a wide variety of known glass, polymeric or other materials. The partially diffusing optical fibers of this invention have applications ranging from illuminated fabrics and toys and to lighting systems and medical instruments.

Abstract: A magnetostrictive application probe is disclosed wherein the probe includes a preassembled sensor element mounted as an application housing installation as an installable unit. The modular nature allows interchanging with various electronic assemblies, and may be an explosion proof installation.

Abstract: A frequency domain electromagnetic geophysical mapping instrument has a transmitter, a transmitter coil connected to the transmitter, the transmitter generating current pulse waveforms formed by half-sinusoidal output waveform segments of a waveform having a frequency equal to a resonant frequency of the transmitter coil, and a receiver, in which the transmitter generates current pulses including pulses comprising a plurality of immediately successive half-sinusoidal waveform segments of common polarity. The pulses immediately succeed each other and are of alternating polarity. The pulse lengths may in this case be equal, or vary in a manner providing a desired output spectrum, for example according to a pseudo-random sequence.

Abstract: Sensors, systems and methods for measuring magnetic field strengths in both AC and DC magnetic fields by using CMR material in tunable, radio-frequency LC oscillators are disclosed.

Abstract: Apparatus and methods are disclosed which provide increased sensitivity, selectivity and dynamic range for non-contact measurement of actual physical and/or kinematic properties of conducting and magnetic materials. The apparatus and methods are based upon various methods for increasing sensitivity, selectivity and dynamic range through proper construction of a magnetometer sensor and for proper selection of operating point parameters for the application. A measurement apparatus for measuring one or more MUT properties includes an electromagnetic winding structure which, when driven by an electric signal, imposes a magnetic field in the MUT and senses an electromagnetic response. An analyzer is provided for applying the electric signal to the winding structure. A property estimator is coupled to the winding structure and translates sensed electromagnetic responses into estimates of one or more preselected properties of the material.

Abstract: A magnetic-field-to-voltage transducer includes a Hall element and a digitally gain-controlled Hall-voltage amplifier that produces an analog voltage Vsig having excursions of one polarity corresponding to the passing of magnetic articles. Vsig is applied to the input of a peak-referenced-threshold signal detector that generates a binary proximity-detector output voltage, Vout, having transitions of one direction upon approaches of gear teeth down to zero speed. A digitally gain-controlled amplifier is connected to the Hall element. A comparator circuit generates a binary signal Vbig (or Vtoobig) that changes from one to another binary level each time that Vsig exceeds a DC target voltage, VTG. The AGC circuit incrementally changes the transducer gain in the direction to bring the peaks in Vsig to just below the target value TTG. Reference voltages VP2 and VN2 are generated that are equal respectively to the most recent peak positive and negative going excursion in Vsig.

Abstract: A resistivity tool suitable for use in a borehole and configured to obtain a resistivity radial profile at multiple depths of investigation in a geological formation comprises a receiver pair and an array of transmitters. The distance of each transmitter from the receivers corresponds to a particular depth of investigation into the formation. Using as few as two transmitters, the resistivity tool derives resistivity values at any number of depths of investigation, including depths of investigation that do not correspond to transmitter/receiver spacings on the tool. A measurement processor combines signals received from the existing transmitters using linear interpolation, geometric interpolation, and/or other techniques to derive the resistivity measurements.

Abstract: A magnetic field sensing element comprising a giant magnetic resistance element formed on a substrate for detecting a change in a magnetic field, an integrated circuit formed on the substrate for carrying out predetermined arithmetic processing based on a change in the magnetic field, and an input side protective resistor and an output side protective resistor provided on the input side and the output side, respectively, of the integrated circuit, wherein the metal film from which the input side resistor and the output side resistor are formed is identical to the metal film from which the integrated circuit is formed.

Abstract: In order to improve the measurement possibilities with regard to a rotating shaft, including the whole angle area (0 to 360°), a rotation angle sensor is mounted that is provided with a radial-bipolar ring-shaped magnetic element (3), three air gaps (5, 6, 7, 8) displaced by an equal angle (&phgr;) being connected with said shaft, and with a stator element (4) of a magnetoconductive material, while a Hall integrated circuit element (1, 2) is inserted in at least two adjacent air gaps (5, 6, 7, 8). The two Hall integrated circuit elements (1, 2) can be connected to an evaluation unit (9) which records a voltage curve of the measured circuit for each circuit element (1, 2), assigns each flow voltage measure to a position angle on the Hall integrated circuit voltage curves, calculates from the position angles assigned to the flow voltage values the actual position angle and gives it as the start signal (A1, A2).

Abstract: A meandering winding magnetometer (MWM) includes a meandering primary winding and at least one sensing winding or coil on a membrane to be pressed against a test surface. The membrane may be supported on a flexible carrier which is translatable into a probe. Abutments in the probe press the carrier against the test surface but allow the carrier and membrane to conform to the test surface. One MWM circuit includes meandering primary and secondary windings. The return leads from the secondary winding return to connector pads in close alignment with the test array, while leads from the primary winding are spaced at least one wavelength from the array. In another MWM circuit, individual sensing loops are positioned within the meandering primary winding. The MWM circuit may be provided on an adhesive tape which may be cut to length.

Abstract: To make it possible for a rotation angle sensor to be manufactured and assembled more easily and more accurately, the part components of a stator element (21) made of a ferritic material are held in a sintered stator body, made by a sintering technique, by at least one holding element in a holding recess of a base element made of a non-magnetizable material. A magnetic holding device (26, 27) is a holding element made by a metal injection moulding (MIM) technique with an at least partly formed magnetic isolation zone and at least one recess. An annular magnetic element (24) is attached inside the MIM holding device by means of at least one slit-shaped recess and at least one compatible linking element, and positioned at a given angle (&agr;) in relation to a gap, between the sintered stator bodies.

Abstract: A method of data acquisition for geophysical surveys. The method includes the steps of providing a least one magnetic sensor unit for sensing and recording magnetic field fluctuations; providing a plurality of electric sensor units for sensing and recording electric currents induced by the magnetic field fluctuations; receiving a satellite based timing signal and responsively synchronizing and bag a position for each of the plurality of electric sensor units and the at least one magnetic sensor unit; and synchronously recording the positions, the magnetic field fluctuations and the electric currents for downloading for processing.

Abstract: An oscillator 12 outputs a constant frequency as a metal object is brought close and this frequency forces oscillation of an oscillating circuit 11 which is sensitive to this metal object, at a level significantly below the critical natural frequency of the oscillating circuit. The oscillating signals S1, S2 are applied to the two inputs of a phase detector 15, such that they can be changed over by means of an inverter device 17, so that the detector can be configured in ferrous mode or in non-ferrous mode.

Abstract: The borehole imaging apparatus of the present invention includes a tool having an array of voltage electrode buttons mounted on a non-conductive pad. A current source and a current return are preferably located on the non-conductive pads at opposite ends thereof. The locations of the current source and return are designed to force a current to flow in the formation parallel to the pad face and non-parallel to the formation boundary layers. According to a method of the invention, the voltage difference between a pair of buttons in the array is proportional to the resistivity of the formation bed adjacent to the buttons. The ratio of voltage differences between two nearby pairs of electrode buttons provides a quantitative measurement of the ratio of shallow resistivity. The resolution of the image produced by the new tool is determined only by the spacing of the buttons. The tool according to the invention produces much better images than the prior art tools when used in OBM wells.

Abstract: A magnetoresistive sensor includes a plurality of multilayered magnetoresistive films arranged in parallel. Each multilayered magnetoresistive film includes at least one pinned ferromagnetic layer and at least one free magnetic layer. Reversion of magnetization of the pinned ferromagnetic layer is pinned, whereas the vector of magnetization of the free ferromagnetic layer freely reverses in response to an external magnetic field. The vectors of magnetization of the pinned ferromagnetic layers in two adjacent multilayered magnetoresistive films are substantially antiparallel to each other.

Abstract: A device for non-contacting measurement of a measuring object is provided. The device includes at least one pair of associated coils, including a transmitter coil and a receiver coil. The transmitter coil generates a time varying magnetic field. In the receiver coil, a voltage is induced. The voltage is dependent on the location of the transmitter coil, the receiver coil and a measuring region of a measuring object. The device comprises a U-shaped structure with two branches. A retaining part is arranged between these branches. The transmitter and receiver coils are fixed to the branches of the U-shaped structure and the measuring object is intended to be arranged centrally in the opening of the U-shaped structure.

Abstract: In normal operation, a sensor element emits information only as to whether two or more field-sensitive components are located in peripheral zones of identical or different electromagnetic field strengths of a pulse generator. In order to permit sensor elements of this type determining immediately upon activation of a supply voltage whether an identical electromagnetic field strength on both components corresponds to a zone of low (L) or high (H) field strength, according to the present invention, the sensor element, upon activation of the supply voltage, is initially operated so that the absolute field strength is measured for a given time. If there is a difference circuit between two field-sensitive components (3, 4), the measurement is carried out because one of the components is temporarily switched off, both components are connected in parallel, or both components are connected in series.

Abstract: In a method of measuring a current, the current is received at a winding and permitted to flow through the winding, which is wound about a core. The flow of the current through the winding induces a first magnetic flux that flows through the core and that tends to drive the core into saturation. The core is actively reset to prevent the core from being saturated at least during selected time intervals. The current is then measured during at least a plurality of the selected time intervals. In a particularly preferred embodiment, the winding is a primary winding and the resetting step includes applying a reset voltage to a secondary winding using a source that is coupled to the secondary winding. The reset voltage determines a rate at which a net magnetic flux that flows in the core changes in a direction away from saturation. Advantageously, the current sensing method has a tremendous dynamic range.

Abstract: A wireline, coiled tubing, and measurement while drilling resistivity tool having three or more receivers is disclosed. This results in a tool capable of gathering substantial resistivity data about a subterranean formation while being drawn quickly past a borehole wall. One embodiment of this resistivity tool includes four receivers and a pair of transmitters, resulting in six resistivity measurements from each firing of a transmitter. The transmitters are arranged to obtain a regularly spaced series of resistivity measurements. The transmitters may be fired at two or more frequencies to result in further information about the formation. Another embodiment of this resistivity tool places its transmitters and receivers to obtain a number of redundant resistivity readings, resulting in error checking and increased reliability. For enhanced performance, transceivers may also be used. An analogous method is also disclosed.