Abstract: The present invention is to provide a current sensor, which can measure accurately current of a wide range, at low cost. A shield plate 12 of ring shape is arranged around a flow direction of a current of the bus bar. When the current flows through the bus bar, magnetic flux density of a magnetic field is generated. A magneto-electronic conversion element detects the magnetic flux density of the magnetic field, and converts the magnetic flux density into an electric signal. Furthermore, the magneto-electronic conversion element is arranged near a position where the previously measured magnetic flux density of the magnetic field, which is generated when a current flows through the bus bar, is minimized between the conductor and the shield plate.

Abstract: Position measurements are often performed using a localization system with a given fixed capture range and accuracy and resolution. Having a fixed capture range often comes at the cost of decreased accuracy and resolution. At the start, a large capture range is provided where the accuracy and resolution is low. In this large capture area, the target area can be identified and aimed at. With this identification, a smaller capture range is iteratively provided and centered around the region of interest, which leads to an increased accuracy and resolution.

Abstract: A sensor signal conditioning circuit and sensor system incorporating the same. In one embodiment, the signal conditioning circuit includes a DC-coupled detector that converts a sensor signal into a discrete level signal. An AC-coupled detector having a dynamic DC threshold input also converts the sensor signal into a discrete level signal and has a startup delay associated with the dynamic DC threshold input. The signal conditioning circuit further includes a device that inhibits the DC-coupled detector responsive to the dynamic DC threshold input reaching a specified threshold voltage level such that the AC-coupled detector provides the detected output during steady-state sensor operation.

Abstract: Metal detectors include a sense coil coupled to an analog to digital converter that produces a numeric representation of an electrical signal associated with a conductive object situated in an active region of a sense coil. The numeric representation is processed to obtain a noise contribution associated with random noise, fixed pattern noise, and/or thermal drift. The noise is subtracted from the numeric representation to produce a numeric difference. The numeric difference includes contributions associated with conductive objects located in a sense volume defined by the sense coil. The numeric difference (or the numeric representation) can be digitally processed with, for example, a matched filter to enhance the conductive object contribution. The matched filter can be based on a measured sense coil speed or can be based on typical sense coil speeds.

Abstract: A magnetic sensor (MS) for sensing a magnetic stray field (SF) generated by magnetizable object (SPB) when magnetized and for generating an electrical object signal (UOB) which depends on the sensed magnetic stray field (SF), comprising a magnetic field generator (WR1, WR2) for generating a magnetic main field (H) for magnetizing the magnetizable object (SPB), and cross-talk reduction means for reducing the effect of a cross talk signal component in the electrical object signal (UOB) caused by magnetic cross-talk between the magnetic main field (H) and the magnetic stray field (SF), wherein the cross-talk reduction means is arranged for distinguishing a signal property between the cross-talk signal component and the remaining part of the electrical object signal (UOB) and for generating an electrical output signal (Uo).

Abstract: A magnetic sensor includes a pair of serially-connected magneto-resistive elements (1a, 1b), one of which serves as a sensing portion (6) made to face a magnetic detecting medium (S), and the other of which serves as a temperature-compensating portion (7). The magnetic sensor also includes a magnet (5) that gives magnetic biases having different types of magnetism to the magneto-resistive elements (1a, 1b), and a detection circuit (8) that applies DC voltage to between ends of the serially-connected magneto-resistive elements (1a, 1b) and detects a potential change of the common connection point of the magneto-resistive elements (1a, 1b).

Abstract: A magnetic sensor circuit supplying an excitation current to an MI device, and having a detection signal supplied thereto corresponding to a magnetic field intensity from the MI device based on the excitation current. The magnetic sensor circuit includes a pulse current supplying circuit supplying a pulse current to the MI device; a sample-and-hold circuit maintaining an approximately peak value of the detection signal and outputting a hold signal; and a temperature compensation part compensating temperature characteristics of the magnetic sensor circuit with respect to the hold signal. The sample-and-hold circuit may include a switching circuit and a holding capacitor. The switching circuit may have an opening/closing control signal supplied thereto based on timing of the pulse current.

Abstract: A closed loop magnetic sensor system for measuring an input magnetic field from a magnetic field source has a compensation circuit, which can be for example a printed wire board, and a magnetic sensor, such as a Magnetoresistive (MR) sensor, for measuring an input magnetic field. Preferably, the magnetic sensor is magnetically coupled to the compensation circuit by arranging the magnetic sensor in an air gap provided in the compensation circuit. The compensation circuit has a compensating conductor, arranged on or in a dielectric medium, which can be configured as a plurality of nested coils. Electrical control circuitry, electrically, coupled to the magnetic sensor and compensating conductor, is adapted and arranged to drive a feedback current through the compensating conductor according to the output of the magnetic sensor such that the input magnetic field is substantially compensated at the magnetic sensor. The magnetic system can serve as current sensor for sensing current through a primary conductor.

Abstract: Sensor condition verification may be performed on electromagnetic sensors and sensor arrays mounted to a material surface. The sensors typically have a periodic winding or electrode structure that creates a periodic sensing field when driven by an electrical signal. The sensors can be thin and flexible so that they conform to the surface of the test material. Monitoring the conductivity changes of a test material, with changes in temperature, may provide a mechanism for testing the integrity of the sensor. Changes in the conductivity, due to changes in temperature, without significant lift-off changes may verify the calibration of the sensor and that the sensor elements themselves are intact.

Abstract: Method and apparatus for measuring an entity of a magnetic field using a Hall sensor which is provided with at least one Hall plate which has a group of two pairs of terminals located at a distance from one another, an excitation signal supplied from a source to one pair of terminals and a detection signal, which forms a representation of the entity, which is tapped off from the other pair of terminals by a processing circuit. The source is a voltage source of which an impedance is negligible for use of the sensor, and the processing circuit has a negligible input impedance for tapping off me detection signal as a short-circuit current.

Abstract: A sensor device (40) and a method for detection of the presence of at least one magnetic particle (46) are described. More particularly, a sensor device (40) comprising at least one magnetic field generating means (41) and at least one magnetic sensor element (42) is provided. The sensor device (40) furthermore comprises an exclusion zone (44), such as a spacer (44b) at the sensor surface (45), for excluding magnetic particles or beads (46) in the relative vicinity of the magnetic sensor element (42). The sensor device (40) according to the invention shows high depth or bulk sensitivity.

Abstract: There is provided an inspection device for the detection of flaws in a component. The inspection device comprises a magnetic field generator, a first array of magnetoresistive sensors and a second array of magnetoresistive sensors, in which the second array is substantially orthogonal to the first array. The signals generated by the first and second arrays are utilized by a processing element to determine a curl of the magnetic field signals effected by the eddy currents including the eddy currents encountering a flaw in the component. The curl of the magnetic field signals is then used to better illustrate the existence of the flaw and various parameters of the flaw. The magnetic field generator comprises a coil or linear arrays of conductors. The inspection device is preferably contained (1) within a hand-held housing or (2) mounted on any automated inspection platform, and advantageously comprises a display for illustration of the detected flaw.

Abstract: A compensation signal, which derives the mechanical stress, which acts on an integrated semiconductor circuit, from two partial compensation signals, which are generated by semiconductor elements with different stress characteristics, can be determined in more detail when the temperature dependence of a ratio of the partial compensation signals is also considered, wherein particularly a deviation of the ratio of the partial compensation signal to an ideal ratio is considered. Thereby, the rise in accuracy of the stress determination results from determining a deviation of the partial compensation signals, on which the stress determination is based, from a nominal behavior in a stress-free state, so that the deviation of the nominal behavior, which can be based, for example, on a variation of the process parameters in a production process of a semiconductor circuit, can also be considered, in addition to the known temperature behavior.

Abstract: A voltage is applied across gate electrodes (103A) and (103B) in a two-dimensional electronic system (101) placed under a magnetic field, and the polarity of an electric current passed between ohmic electrodes (102D) and (102S) is selected to bring about inversion of electron spins based on a non-equilibrium distribution of electrons in a quantum Hall edge state and to initialize the polarization of nuclear spins. An oscillatory electric field of a nuclear magnetic resonance frequency is applied to coplanar waveguides (104A) and (104B) to control the nuclear spin polarization. The controlled spin polarization is read out by measuring the Hall resistance from ohmic electrodes (102VA) and (102VB).

Abstract: A method of determining the thickness of a conductive film is disclosed. The method employs measured voltage and current responses that have been temperature-compensated to determine the thickness of the conductive film. The temperature compensation uses a temperature compensation factor obtained from a calibration substrate different from the target substrate on which the conductive film being measured is disposed. The calibration substrate has a conductive film formed of a conductive material that is substantially similar to the conductive material of the target substrate.

Abstract: Methods and systems a method of assembling a proximity probe are provided. The method includes determining a coil wire dimension and coil geometry for the probe such that a resistance versus temperature profile of the coil is approximately constant when the coil is excited with an excitation frequency of approximately 150 kilohertz to approximately 350 kilohertz, and adjusting the coil geometry such that a resistance versus temperature profile of the coil is substantially constant.

Abstract: A method of compensating sensor data and a method of evaluating an interlock of an interlock system, in which an allowable variation between sensors varying depending on a driving time for a set of equipment, an RF time, the number of wafers, etc. is minimized, thereby enhancing detection reliability of a defective wafer.

Abstract: Systems and methods are disclosed that compensate for temperature drift in a proximity sensor, such as an extended range inductive proximity sensor. Voltage measurement can be taken before, and during damped oscillatory decay of a voltage in a resonant circuit in the proximity sensor to determine a value, ?, associated with an inductive time constant for the resonant circuit. A target-induced inductance value can be isolated, via manipulation of the gamma value, and compared to a predetermined threshold value to determine whether the target has been sensed by the proximity sensor.

Abstract: Systems and methods are disclosed that facilitate determining coil temperature in a proximity sensor, such as an extended range inductive proximity sensor. Voltage measurements can be taken before, and during, damped oscillatory decay of a voltage in a resonant circuit in the proximity sensor to determine a value, ?, associated with an inductive time constant for the resonant circuit. The gamma value comprises information related to both inductance and resistance in the sensor coil, and can be employed to determine coil temperature. Derivation of the gamma value, and thus of coil temperature, can utilize a current pulse of a duration of approximately one RC time constant of the resonant circuit, thus mitigating current consumption by the proximity sensor during temperature assessment.

Abstract: The present invention relates to a manually operated working tool such as an internal combustion operated setting tool for driving in fastening elements such as nails, bolts, pins into a magnetizable substrate, having an inductive metal detector assembly (20) with at least one excitation coil arrangement (21) and evaluation means. A means for generating an alternating current for the excitation coil arrangement (21) having at least two consecutive frequencies fn from a start frequency f0 to an end frequency fmax is provided on the inductive metal detector assembly (20).

Abstract: A differential magnetometer consisting of at least one active coil (4, 5) and a receiver coil (10) for which the windings are installed differentially, is provided with a measurement circuit (14) with a slaving device that corrects dissymmetry appearing between windings (11, 12) to eliminate residual induction at the frequency of the magnetic excitation field, intended to make the measurement coil (10) more sensitive without applying a voltage to it.

Abstract: The magnetometer includes a magnetic core (1) with at least one branch (2, 3), at least one exciting coil (4, 5) and one take-up coil (10) sensitive to ambient fields thanks to the excitation field (B). An additional magnetic field, to advantage perpendicular to the previous ones, is added to eliminate very low frequency noises, without it being measured.

Abstract: A sound variation indication apparatus includes a comparison element, an interval checker, and an indication generator. The comparison element receives an audio signal and compares it to a check value to provide a status signal indicating a presence and absence of an expected sound input. The interval checker detects the status signal at predetermined intervals, to provide an interval output. The indication generator generates an indication if the interval output is an absence representation. A process of generating an indication on absence of a sound input includes providing an audio signal based on a sound input and comparing the audio signal to a check value, providing a status signal indicating a presence and absence of the sound input. A status signal value is determined at predetermined intervals, to provide an interval output. An indication is generated if the interval output is an absence representation.

Abstract: A SQUID (Superconducting QUantum Interference Device) sensor using an auxiliary sensor, includes a SQUID sensing unit having a SQUID and a first feedback coil for creating a magnetic field at a periphery of the SQUID; an auxiliary sensor having a lower magnetic sensitivity and a higher operation range than the SQUID sensing unit; and a sensor reading unit for operating the SQUID sensing unit and the auxiliary sensor to read out a signal of the SQUID and at the same time, supplying the SQUID sensing unit with an offset magnetic field through the first feedback coil.

Abstract: Methods for eliminating error in magnetic sensors used for measuring a coating thickness caused by static or changing external magnetic fields or temperature. The methods involve measuring an output voltage of a magnetic sensor, corresponding to an internal resistance of the magnetic sensor, in a static or changing magnetic field or external temperature, storing the value of the output voltage, performing mathematical operations with the stored value of the output voltage, and correcting the output voltage of the magnetic sensor to accurately indicate a coating thickness.

Abstract: A non-destructive inspection device (X1) includes an exciting pole (10) having a magnetic flux exciting surface (11) for exciting a magnetic flux to form a magnetic field in an inspection target, a recovering pole (30) having a magnetic flux recovering surface (31) for recovering the magnetic flux excited from the magnetic flux exciting surface (11), and a coil array (50) having a plurality of loop coils though which the magnetic flux excited from the magnetic flux exciting surface (11) passes prior to reaching the inspection target, the coil array being offset toward the recovering pole (30) with respect to the magnetic flux exciting surface (11).

Abstract: A method and apparatus for determining the velocity of a rotating device is described herein. The apparatus includes a magnet assembly affixed to a rotating shaft of a rotating device and a circuit assembly. The circuit assembly includes a circuit interconnection having a sense coil and sensors affixed thereto. The circuit assembly is adapted to be in proximity to the magnet assembly, wherein the magnet assembly combines with the circuit assembly to form an air core electric machine such that voltages generated from the sense coil exhibits an amplitude proportional to the velocity.

Abstract: A method for measuring conductance of a sample using an eddy current probe with a sensing coil. The method includes N repetitions of measuring first and second voltage pairs including in-phase and quadrature components of an induced AC voltage in the sensing coil, calibrating the first signal based on the measured second signal at a different separation from the sample and reference material, determining a conductance function relating conductance with location along the selected curve, processing the calibrated first voltage pairs to generate a lift-off curve, determining an intersection voltage pair representing intersection of the lift-off curve with a selected curve, and determining the conductance of the sample from the intersection voltage pair and the conductance function.

Abstract: A sensing device includes a circuit that compensates for time and spatial changes in temperature. The circuit includes elements to correct for variation in permeability of a highly permeable core of a differential variable reluctance transducer as temperature changes. The circuit also provides correction for temperature gradients across coils of the transducer.

Abstract: A microelectromechanical system (MEMS) device comprising a base structure; a magnetic sensor attached to the base structure and operable for sensing a magnetic field and allowing for a continuous variation of an amplification of the magnetic field at a position at the magnetic sensor; and for receiving a DC voltage and an AC modulation voltage in the MEMS device; a pair of flux concentrators attached to the magnetic sensor; and a pair of electrostatic comb drives, each coupled to a respective flux concentrator such that when the pair of electrostatic comb drives are excited by a modulating electrical signal, each flux concentrator oscillates linearly at a prescribed frequency; and a pair of bias members (mechanical spring connectors) connecting the flux concentrators to one another.

Abstract: A method for monitoring an inspection sample includes generating inspection data comprising resistance and reactance measurements that are obtained from an inspection sample having a conductive layer of unknown thickness. Calibration data is used for estimating the thickness of the conductive layer of the inspection sample. This calibration data includes resistance and reactance measurements obtained from one or more calibration samples, each calibration sample having a conductive layer of known thickness. The conductive layers of the inspection sample and the calibration samples comprise different materials having a known conductive relationship.

Abstract: An improved polar coordinates sensor comprising a pot-core half having a concentric winding window surrounded by a washer-like high conductive Lenz lens. A toroidal core stack concentrically disposed at the base end of the pot-core half, the pot-core half, Lenz lens and the toroidal core stack being disposed coaxially with aligned winding windows. X-y coordinates excitation winding distributions being shuttled through the coaxial aligned windows to encircle the cross-section of pot-core half, Lenz lens and toroidal core stack forming a series circuit. X-y excitation currents being connected to the excitation distributions to induce a hemispherical driving field. The inductive reactance of the series coupled toroidal core stack allows an increased degree of differential redistribution of driving flux in response to probe tilt. A rotating/non-rotating excitation method, of which a source of the x-y signals may include electromechanical resolver type waveforms.

Abstract: The present invention provides a method for the direct measurement and quantification of the material volume loss on and beneath a first surface of a substrate and thus provides an accurate depiction of the profile of the substrate. The method of the invention comprises inducing multiple eddy currents in a test substrate to determine volume loss.

Abstract: A method for compensation of dynamic error signals of a chopped Hall sensor that comprises at least one Hall sensor element comprising a plurality of terminal pairs for impressing an excitation current through the Hall sensor element and for taking a Hall voltage. The terminal pairs for impressing the excitation current and for taking the Hall voltage are switched in a first and/or second rotational sense. In order to compensate dynamic error signals caused by the switching, the Hall voltages taken at the terminal pairs when switching in the first rotational sense are supplied to a summation and/or averaging analysis unit together with the Hall voltages taken at the terminal pairs when switching in the second rotational sense.

Abstract: A method for detecting a thickness of a layer of a wafer to be processed is provided. The method includes defining a plurality of sensors configured to create a set of complementary sensors proximate the wafer. Further included in the method is distributing the plurality of sensors along a particular radius of the wafer such that each sensor of the plurality of sensors is out of phase with an adjacent sensor by a same angle. The method also includes measuring signals generated by the plurality of sensors. Further included is averaging the signals generated by the plurality of sensors so as to generate a combination signal. The averaging is configured to remove noise from the combination signal such that the combination signal is capable of being correlated to identify the thickness of the layer.

Abstract: In an apparatus for measuring a specific absorption rate (SAR) for use in a radio apparatus, a first near magnetic field of a radio wave radiated from a reference radio apparatus is measured in free space, and an SAR of the radio wave radiated from the reference radio apparatus by using a predetermined phantom according to a predetermined measurement method. A transformation factor ? is calculated by dividing the measured SAR by a square value of the measured first near magnetic field, and a second near magnetic field of a radio wave radiated from a radio apparatus to be measured is measured in free space. Then an SAR of the radio wave radiated from the radio apparatus to be measured is estimated and calculated by multiplying a square value of the measured second near magnetic field by the calculated transformation factor ?.

Abstract: A circuit for generating an output signal, which depends on a physical useful quantity includes means for detecting the physical useful quantity, wherein the means for detecting is arranged to generate an output signal, which depends on the physical useful quantity, a control signal for the means for detecting and, with an unchanged control signal, on an external control quantity. The circuit further includes sensor means for detecting the external disturbing quantity and for providing a sensor signal, which depends on the external disturbing quantity and means for processing the sensor signal to influence the control signal dependent on the sensor signal such that the influence of the external disturbing quantity on the output signal is reduced.

Abstract: A method for detecting a thickness of a layer of a wafer is provided. The method includes defining a particular radius of a wafer carrier configured to engage the wafer to be processed. The method also includes providing a plurality of sensors configured to create a set of complementary sensors. Further included in the method is distributing the plurality of sensors along the particular radius within the wafer carrier such that each sensor of the plurality of sensors is out of phase with an adjacent sensor by a same angle. The method also includes measuring signals generated by the plurality of sensors. Further included is averaging the signals generated by the plurality of sensors so as to generate a combination signal. The averaging is configured to remove noise from the combination signal such that the combination signal is capable of being correlated to identify the thickness of the layer.

Abstract: The invention relates to a method and a system for determining the orientation of an external magnetic field by means of giant magneto-resistor (GMR) sensors. A sensor circuit is provided with two or more sub-circuits each having two GMR sensors connected in series. Three respective sensor voltages are obtained and a scaling factor is determined from differences in these voltages. An external magnetic field orientation is determined based on a scaling factor applied to the difference voltages. The inventive method enables signals from the GRM sensors to be reprocessed easily in order to compensate the temperature dependence of the signals.

Abstract: A circuit (1) for compensating for temperature with a sensor operating by the eddy current principle for measuring physical conditions of an object. The circuit includes an evaluation unit (3) for evaluating a measuring signal (100) of the sensor (2). The sensor (2) and the evaluation unit (3) are interconnected via a connection cable (4). For the purpose of minimizing or preventing to the greatest extent temperature caused interferences, an additional compensation line (5) is provided which compensates for the temperature of the connection cable (4). A corresponding method for compensating for temperature is described.

Abstract: Drift compensation systems and methods are presented for compensating the drift of a sensor within a manufacturing lot. The system comprises a sensor test sample manufactured from a lot of material having substantially similar chemical or metallurgical properties, a drift characterization tester, wherein the test sample is exposed to a predetermined thermal environment. Measurements of the test sample output are analyzed to provide a drift function describing the relationship between time and temperature from the thermal exposure measurements of the test sample in the drift characterization tester. Parameters associated with the drift function and the sensor test sample are stored in a memory storage component associated with a second sensor. The second sensor is manufactured from the same lot of material as the sensor test sample. A sensor system is manufactured comprising the second sensor and the memory storage component.

Abstract: A device for measuring a motion of a moving electrically conducting body is disclosed. A magnetic field generated by, for example, electromagnets or permanent magnets, penetrates at least a partial area of the moving body. Two or more measuring devices are arranged outside the magnetic field to measure a measurement magnetic field that is induced by electrical currents in the moving body. The measuring devices are arranged essentially symmetrically with respect to the magnetic field generating means or the moving body. The measurement magnetic field represents at least one motion variable of the moving body. The measuring device is thereby no longer subjected to the temperature-dependent variations of the exciting field.

Abstract: A sensing device includes a circuit that compensates for time and spatial changes in temperature. The circuit includes elements to correct for variation in permeability of a highly permeable core of a differential variable reluctance transducer as temperature changes. The circuit also provides correction for temperature gradients across coils of the transducer.

Abstract: A distortion compensation method includes determining an undisturbed phase for at least one of a first position indication signal and a second position indication signal. The method includes determining an undisturbed ratio that relates the amplitude of the first position indication signal at a first frequency to the amplitude of the second position indication signal at a second frequency. The method also includes determining a disturbed amplitude of the position indication signal and adjusting a position indication based on the disturbed amplitude and phase, the undisturbed amplitude ratio, and the undisturbed phase. The method further comprises determining a relationship between the eddy current phase of the first position indication signal and the second position indication signal.

Abstract: A magnetic-sensing apparatus and methods of making and using thereof are disclosed. The sensing apparatus may have one or more magneto-resistive-sensing elements, one ore more reorientation elements for adjusting the magneto-resistive-sensing elements, and semiconductor circuitry having driver circuitry for controlling the reorientation elements. The magneto-resistive-sensing elements, reorientation elements and semiconductor circuitry may be disposed in single package and/or monolithically formed on a single chip. Alternatively, some of the semiconductor circuitry may be monolithically formed on a first chip with the magneto-resistive-sensing elements, while a second portion of the semiconductor circuitry may be formed on a second chip. The first and second chips may be placed in close proximity and electrically connected together. Alternatively the chips may have no intentional electrical interaction.

Abstract: The magnetometer includes a magnetic core (1) with at least one branch (2, 3), at least one exciting coil (4, 5) and one take-up coil (10) sensitive to ambient fields thanks to the excitation field (B). An additional magnetic field, to advantage perpendicular to the previous ones, is added to eliminate very low frequency noises, without it being measured.

Abstract: A Hall sensor array for offset-compensated magnetic field measurement comprises a first and at least one additional pair of Hall sensor elements. Each Hall sensor element has four terminals, of which two act as power supply terminals for supplying an operating current and two act as measurement terminals for measuring a Hall voltage. Respective first supply terminals of each Hall sensor element are connected together and to a first terminal of a common voltage source and respective second supply terminals of each Hall sensor element are connected together and to a second terminal of the common voltage source so that the common voltage source supplies an operating current for the Hall sensor elements. The Hall sensor elements are operated in the spinning current mode so that the offset voltages of the Hall sensor elements approximately cancel one another out in a revolution so that the Hall signal contributions which actually depend on the magnetic field remain.

Abstract: A method and apparatus are provided for measuring the thickness of a test object. The apparatus includes an eddy current sensor having first and second sensor heads. The sensor heads are positioned to have a predetermined gap therebetween for passage by at least a portion of the test object through the gap. The sensor heads make measurements at given sampling locations on the test object as the test object is moved through the gap. The apparatus also includes a position sensing mechanism to determine positions of the sampling locations on the test object. The apparatus also includes an evaluation circuit in communication with the eddy current sensor and to the position sensing mechanism for determining the thickness of the test object at the sampling locations.

Abstract: A coating thickness measuring instrument is provided. The coating thickness measuring instrument has a first mode of operation in which it is operative to make measurements with a first resolution and a second mode of operation in which it is operative to make measurements with a second resolution, the first resolution being greater than the second. The instrument may provide a first short range high resolution mode and a second long range low resolution mode. The first range may be contained in or overlap the second range.

Abstract: A method for monitoring wall thickness of an object having an electrically conductive wall, using a pulsed eddy current probe comprising a transmitter means and a receiver means, which method comprises selecting an inspection location on the wall; at a plurality of inspection times &thgr;m (m=2, . . . ,M), arranging the probe in a predetermined position relative to the inspection location, inducing transient eddy currents in the object by activating the transmitter means, recording signals Vm with the receiver means; determining, for each inspection time &thgr;m, a temperature Tm indicative of the temperature of the object at the inspection location; and determining, from each of the signals Vm, a wall thickness dm pertaining to inspection time &thgr;m, wherein the temperature Tm is taken into account.