Abstract: The present invention relates to a magnetic sensor with a sensitivity measuring function and a method thereof. Magnetic sensitivity surfaces detect flux density, and a switching unit extracts magnetic field intensity information of each axis, and inputs it to a sensitivity calculating unit. The sensitivity calculating unit calculates the sensitivity from the magnetic field intensity information about the individual axes from the magnetic sensitivity surfaces. The sensitivity calculating unit includes an axial component analyzing unit for analyzing the flux density from the magnetic sensitivity surfaces into magnetic components of the individual axes; a sensitivity decision unit for deciding the sensitivity by comparing the individual axial components of the magnetic field intensity from the axial component analyzing unit with a reference value; and a sensitivity correction unit for carrying out sensitivity correction in accordance with the sensitivity information from the sensitivity decision unit.

Abstract: An arrangement for influencing and/or detecting magnetic particles, a method for adjusting such an arrangement and a method for influencing and/or detecting magnetic particles in a region of action is disclosed, which arrangement comprises selection means for generating a magnetic selection field having a pattern in space of its magnetic field strength such that a first sub-zone having a low magnetic field strength and a second sub-zone having a higher magnetic field strength are formed in the region of action, drive means for changing the position in space of the two sub-zones in the region of action by means of a magnetic drive field so that the magnetization of the magnetic particles changes locally, receiving means for acquiring signals, which signals depend on the magnetization in the region of action, which magnetization is influenced by the change in the position in space of the first and second sub-zone, wherein the receiving means comprises a first compensation means and a second compensation means t

Abstract: The system (10) and the method are used for forecasting the electrical conductivity of an anode (12) for aluminum production before the anode (12) is baked. In the system (10), at least one receiving coil (20,22) is coupled to an electromagnetic field emitting unit (14,18). A sensing device (30) is connected to the receiving coil (20,22), the sensing device (30) outputting a signal indicative of a variation of the electromagnetic field received by the receiving coil (20,22) as the crude anode (12), or a portion thereof, passes inside the receiving coil (20,22). A value indicative of the electrical conductivity of the anode (12) is then calculated using the signal from the sensing device (30) and signals previously obtained using reference anodes (12). This way, the electrical conductivity of the anodes (12) can be forecasted before the crude anodes (12) are baked.

Abstract: Articles are magnetically tagged by a spatial distribution of passive magnetic elements. Each such magnetic element comprises a layer of soft magnetic material characterised by high permeability, low coercivity and a non-linear B-H characteristic, and formed as a discrete region of such material. Each such magnetic element also has at least one second layer of magnetic material capable of being permanently magnetised at least in a region adjacent the first layer to provide a magnetic bias for the magnetic element. The bias of individual such magnetic elements in the spatial distribution and the particular spatial nature of the distribution enables the article to be magnetically encoded.

Abstract: A hand-held, wand-type buried object detector includes a motion and position sensor that provides data about the sensor head of the buried object detector. An inertial measuring device including three accelerometers and three gyroscopes is one example of a motion and position sensor. The buried object detector includes a processor/communicator device that is capable of processing the data from the motion and position sensor and communicating feedback, based on the processing results, to the operator about the operation of the buried object detector. In one example, a personal digital assistant may be configured for use as a processor/communicator device of a buried object detector.

Abstract: The alternating current potential drop ACPD technique is used to monitor surface cracks in electrical conductors. At high frequencies, the current flows in a superficial skin layer. Two distinct solutions are currently available for the thin and thick skin cases. However, there is no general solution that bridges these two modes in a seamless fashion. A numerical model is used to analyze the ACPD of a surface crack with uniform depth. A general solution is given that bridges the thin and thick skin solutions, which closely matches the numerical results, irrespective of the skin thickness. Methods for estimating depth of cracks are provided for surface penetrating cracks and back cracks.

Abstract: A balancing circuit for a metal detector. The metal detector includes an oscillating power source, a transmit coil connected to the oscillating power source, first and second receive coils inductively coupled to the transmit coil, a first amplitude balancing circuit connected to the first receive coil, and a first phase balancing circuit connected to the first receive coil. The first phase balancing circuit includes a capacitor and a variable resistor.

Abstract: An implementation of a direction finding and magnetic nulling metal detector is provided. Some embodiments of the present invention provide for a metal detector having multiple resonant circuits and associated coils for transmitting a primary transmit signal, transmitting a magnetic nulling signal, and receiving a receive signal. A controller includes logic to process the generate the transmit signals and to process the received signal in order to determine a gradient vector along one or two dimensions, a depth and whether or not a metal object is ferrous.

Abstract: A method and apparatus for conducting eddy current testing of a test object is disclosed, comprising the steps of generating a digital drive signal, converting the digital drive signal to an analog drive signal to drive a coil in a probe; placing the probe in proximity to a test object; receiving an electromagnetic field generated by the test object, which generates an analog return signal; converting the analog return signal to a digital return signal; measuring the amplitude of the digital return signal; measuring the phase shift of the digital return signal compared to the digital drive signal; determining the phase shift angle of the digital return signal based on the phase shift; determining the quadrature components of the digital return signal based on the digital return signal amplitude and the phase shift angle; and analyzing the quadrature components of the digital return signal to determine a material characteristic of the test object.

Abstract: The invention relates to a device for determining an object (14, 16), comprising an inductive sensor (8), a control unit (10) for evaluating phase information of the inductive sensor (8) and display means (4, 4a-d). According to the invention, the display means (4, 4a-d) are configured to indicate a characteristic of the object (14, 16) and the control unit (10) is provided to control the display means (4, 4a-d) in accordance with the phase information.

Abstract: A detector for magnetizable materials operates remotely to determine a amplitude and phase modification of an exciting magnetic field caused by the magnetizable materials. These amplitude and phase measurements are used to create a phase-amplitude trajectory in phase amplitude space, which may be finely divided to distinguish among a number of different types of components.

Abstract: A device for producing a detection signal when interfering, preferably metallic conductive pieces occur in an at least largely non-conductive conveyor stream. An alternating electromagnetic field is built up by an alternating current generator through a transmission coil in a segment of the conveyor stream to be monitored. The changes in amplitude and phase of the alternating electromagnetic field are detected by a coil system that feeds an evaluating circuit for deriving the detection signal, which, when an interfering piece appears, causes a stoppage of the conveyor stream for the purpose of removing the interfering piece. A resetting device (reset button) is also provided which is able to cancel the conveyor stoppage. A device is also provided for blocking the resetting device, controlled by the evaluating circuit, which disables the resetting device as long as the evaluating circuit still emits a detection signal.

Abstract: A method of determining the number of magnetic particles within a sample using a tuned circuit having a capacitor and a coil. The method comprises: a. determining the difference in the resonant frequency of the tuned circuit when the sample is exposed to a magnetic field generated by the coil and when the sample is not exposed to the magnetic field generated by the coil; and b. using the difference in the resonant frequency to determine the number of magnetic particles within the sample.

Abstract: Material properties such as stress in a ferromagnetic material may be measured using an electromagnetic probe. While generating an alternating magnetic field in the object, and sensing the resulting magnetic field with a sensor, the signals from the magnetic sensor may be resolved into in-phase and quadrature components. The signals are affected by both geometrical parameters such as lift-off and by material properties, but these influences may be separated by mapping the in-phase and quadrature components directly into material property and lift-off components, and hence a material property and/or the lift-off may be determined. The mapping may be represented in the impedance plane as two sets of contours representing signal variation with lift-off (A) (for different values of stress) and signal variation with stress (B) (for different values of lift-off), the contours of both sets (A, B) being curved. The stress contours (B) intersect any one liftoff contour (A) at a constant angle.

Abstract: It is disclosed a method of determining the exposure temperature of Al and Cr of a ?/?? MCrAlY-coating after the use in a high temperature environment, the ?/?? MCrAlY-coating exhibiting a non-equilibrium ?/??-microstructure at a temperature lower than the temperature during operation and the depletion of chromium from the ?/??-MCrAlY-coating still allows the ?-Cr phase to form. The coating conductivity and permeability by means of a multifrequency eddy current system is measured at different locations of the component and from the measured conductivity and permeability the exposure temperature of said different locations of the components is determined.

Abstract: A detection system is provided which is configured to have a transmitter capable of interacting with an object by generating a field, and a multiplicity of receivers operative to measure changes in the environment caused by the object's response to the generated field and mounted to a closed-looped belt, which is displaceable in a proximity to the object.

Abstract: A metallic contaminant detecting method and apparatus according to the present invention detect metallic contaminants mixed in objects under inspection, such as food products, pharmaceuticals, and materials for industrial use, which are wrapped in electrically conductive packaging materials, e.g. aluminum. A small magnetic field is generated by applying a voltage to coils (10, 11) or supplying an electric current to the coils. A detection magnetic field generated from a metallic contaminant in response to the small magnetic field is detected as a detection voltage or a detection current of the coils (10, 11), and a detection signal is output. The detection signal is analyzed to detect the metallic contaminant. The small magnetic field is created by applying a small voltage or supplying a small electric current to the coils (10, 11) and using a non-linear portion of the magnetic field characteristics of cores constituting the coils (10, 11).

Abstract: An eddy current sensor and a method for detecting the thickness of a film formed on a substrate. The eddy current sensor, which is capable of stable operation, is operable to accurately detect a polishing endpoint. The eddy current sensor detects the thickness of a conductive film from a change in an eddy current loss generated in the conductive film. The eddy current sensor comprises a sensor coil for generating an eddy current in the conductive film, and an active element unit connected to the sensor coil for oscillating a variable frequency corresponding to the eddy current loss. The sensor coil and active element unit are integrated to form the eddy current sensor. Alternatively, the eddy current sensor comprises a sensor coil for generating an eddy current in the conductive film, and a detector for detecting a change in the thickness of the conductive film from a change in a resistance component in an impedance formed by the sensor coil and conductive film.

Abstract: A metal detector has a circular excitation coil (10) through which foodstuffs to be tested (65) pass, on a conveyor belt (40). The excitation coil (10) is excited by a stable oscillator (50) and the lines of flux generated by the excitation coil (10) link two receiver coils (20, 30) equidistantly spaced either side of the excitation coil (10). As a foodstuff (65) having a foreign ferromagnetic or electrically conductive object therein passes through the receiver coils (20, 30), a voltage is induced in them. This induced voltage is phase compensated. The change in amplitude or frequency of the oscillator (50) as the foodstuff (65) moves through the excitation coil (10) is also passed to the processor (70) which removes the artifacts from the detector signal caused by the volume of the foodstuff (65) itself. The resultant signal, which was previously swamped by the effect of the volume of the foodstuff itself, can then be detected and the foodstuff can be removed from the conveyor (40).

Abstract: A highly accurate rotation angle detection device is realized by correcting a detecting position error caused by a machining error such as deterioration of roundness of an internal diameter of a stator. The rotation angle detection device is provided with a stator (12), which is provided with an exciting winding of one phase and two-phase output windings, and a rotor (13) having salient poles, in which the stator (12) has a plurality of teeth (11), the two-phase output windings are wound around the plurality of teeth, and the plurality of teeth include teeth for which the number of turns of the output windings is N and at least one of teeth for which the number of turns of the output windings is N±m (it is assumed that N and m are positive integers and N>m) and teeth for which the number of turns is m.

Abstract: A metallic contaminant detecting method and apparatus according to the present invention detect metallic contaminants mixed in objects under inspection, such as food products, pharmaceuticals, and materials for industrial use, which are wrapped in electrically conductive packaging materials, e.g. aluminum. A small magnetic field is generated by applying a voltage to coils (10, 11) or supplying an electric current to the coils. A detection magnetic field generated from a metallic contaminant in response to the small magnetic field is detected as a detection voltage or a detection current of the coils (10, 11), and a detection signal is output. The detection signal is analyzed to detect the metallic contaminant. The small magnetic field is created by applying a small voltage or supplying a small electric current to the coils (10, 11) and using a non-linear portion of the magnetic field characteristics of cores constituting the coils (10, 11).

Abstract: A detector for magnetizable materials operates remotely to determine a amplitude and phase modification of an exciting magnetic field caused by the magnetizable materials. These amplitude and phase measurements are used to create a phase-amplitude trajectory in phase amplitude space, which may be finely divided to distinguish among a number of different types of components.

Abstract: A sensor for monitoring a conductive film in a substrate during chemical mechanical polishing generates an alternating magnetic field that impinges a substrate and induces eddy currents. The sensor can have a core, a first coil wound around a first portion of the core and a second coil wound around a second portion of the core. The sensor can be positioned on a side of the polishing surface opposite the substrate. The sensor can detect a phase difference between a drive signal and a measured signal.

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: 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: Systems and methods consistent with principles of the present invention allow contactless measuring of various kinds of electrical activity within an integrated circuit. The invention can be used for high-bandwidth, at speed testing of various devices on a wafer during the various stages of device processing, or on packaged parts at the end of the manufacturing cycle. Power is applied to the test circuit using conventional mechanical probes or other means, such as CW laser light applied to a photoreceiver provided on the test circuit. The electrical test signal is introduced into the test circuit by stimulating the circuit using a contactless method, such as by directing the output of one or more modelocked lasers onto high-speed receivers on the circuit, or by using a high-speed pulsed diode laser.

Abstract: A method for detecting changes of magnetic response of at least one magnetic particle provided with a external layer in a carrier fluid, comprising measuring the characteristic rotation time of the magnetic particle with respect to the external layer, and measuring Brownian relaxation in the carrier fluid under the influence of an external alternating magnetic field. The method implies that upon modification of the effective volume of the particle or its interaction with the carrier fluid, a hydrodynamic volume of the particle changes, which implies a change of the frequency (ƒmax) at which an out of phase component of the magnetic susceptibility has its maximum.

Abstract: The present invention relates to a method, an apparatus and a computer program for inspecting laminated iron cores (1) of electrical machines for interlamination shorts, in which the laminated iron core (1) is magnetized by means of an auxiliary winding, and the iron surface is scanned by means of at least one measurement coil arrangement (2) with a downstream measurement device. In this case, unique and quantifiable localization of interlamination shorts is achieved by using both the phase (8) and the amplitude (7) of the electrical signal which is induced in the at least one measurement coil arrangement (2), in combined form.

Abstract: A method and system for determining and compensating for phase and time errors in an optical receiver. The method and system includes use of a measurement and reference signal; deriving phase and time errors; and providing compensation values to the optical receiver. The operating frequency and/or other operating parameters associated with phase and time errors are determined and recorded to allow for proper compensation to the optical receiver.

Abstract: A detector for magnetizable materials operates remotely to determine a amplitude and phase modification of an exciting magnetic field caused by the magnetizable materials. These amplitude and phase measurements are used to create a phase-amplitude trajectory in phase amplitude space, which may be finely divided to distinguish among a number of different types of components.

Abstract: A method of detecting undesired metal objects in a document feed path and a document processing apparatus that includes a feeder for transporting document sheets along a feed path; and a detector for detecting the presence of foreign metal objects in said feed path. The detector comprises a source of alternating electrical energy connected to a conductive transmitter loop for generating a pulsed magnetic field proximate the feed path and a conductive receiver loop that receives reflected magnetic field signals. The reflected magnetic signals induce electrical signals in the receiver loop which are amplified and processed to produce output signals which are sent to a phase shift analyzer which discriminates among output signals produced in the receiver loop by magnetic reflections from metal objects of varying types to provide an output signal when an undesired metal object in the feed path is detected.

Abstract: An eddy current probe comprising two solenoid coils wound around a common rectangular wafer base of high permeability material extending beyond the coils at wafer corners with the wafer becoming the solenoid core. Posts also of high permeability material depend from a wafer front at its corners with coils crossing orthogonally on the wafer. The coils are connected to alternating current to produce magnetic fields that have like magnetic poles at wafer corners diagonally opposed across the wafer, the coils switching in phase to alternate the magnetic field between posts at base diagonal corners. With the posts at the wafer base corners, the combined magnetic fields generated from the orthogonal coils conduct through the posts and emanate from post ends. The post ends have a curvature matching that of a material to be tested for better coupling the magnetic field into the material.

Abstract: A method for distinguishing between a semi-soft magnetic material, having a magnetic saturation field H sub s ranging from 100A/m to 3000 A/m, and a soft magnetic material, having a magnetic saturation field H sub s ranging from 3 A/m to 100 A/m, includes (a) emitting an electromagnetic drive signal of one or more particular frequencies to an article so that any present semi-soft magnetic material or soft magnetic material in the article go into saturation for both positive and negative magnetic fields; (b) detecting an electromagnetic detection signal (20) emanating from the article; (c) measuring time or relative phase delays (A, B) between one or more reference points of the drive signal and points at which positive and negative peaks of the detection signal occur; (e) comparing the measured time or relative phase delays with values which are typical for semi-soft magnetic or soft magnetic features in order to make a decision whether the material is soft magnetic or semi-soft magnetic.

Abstract: A metallic contaminant detecting method and apparatus according to the present invention detect metallic contaminants mixed in objects under inspection, such as food products, pharmaceuticals, and materials for industrial use, which are wrapped in electrically conductive packaging materials, e.g. aluminum.

Abstract: A rotation sensor provided with a first rotor fixed to a shaft, a second rotor fixed to the same or other shaft and adjoining the first rotor, and a core having a resonance coil, arranged around the first rotor, and which coil forms a magnetic circuit working with the first rotor. The first rotor is formed of a magnetic material comprising an insulator; an irregular magnetic field is formed with the core; and the second rotor is provided with a conductor cutting across areas of different intensities of the irregular magnetic field in accordance with the difference of the angle of rotation when a difference in the angle of relative rotation occurs at a shaft position where the first rotor is fixed and at a shaft position where the second rotor is fixed.

Abstract: The present invention relates to a method for detecting changes of magnetic response of at least one magnetic particle provided with an external layer in a carrier fluid, wherein the method comprises using a measuring method comprising measuring the characteristic rotation time of said magnetic particle with respect to said external layer, which measuring method involves measuring Brownian relaxation in said carrier fluid under the influence of an external alternating magnetic field. The method implies that upon modification of the effective volume of the particle or its interaction with the carrier fluid a hydrodynamic volume of the particle changes, which implies a change of the frequency (fmax) where an out of phase component of the magnetic susceptibility has its maximum.

Abstract: Metal detector and method in which soil mineralization effects and responses to other undesired materials are eliminated. A periodic excitation signal is transmitted into an area where a target is to be detected, and signals returned by the target are processed to provide an output signal corresponding to the target. A plurality of signals are extracted from the output signal during different phase intervals in the period of the excitation signal and processed to provide signals which are free from ferrite response and/or response to other undesired materials. The signals which are free from response to ferrite and/or other undesired materials are then compared to identify the target.

Abstract: A detector for magnetizable materials operates remotely to determine a amplitude and phase modification of an exciting magnetic field caused by the magnetizable materials. These amplitude and phase measurements are used to create a phase-amplitude trajectory in phase amplitude space, which may be finely divided to distinguish among a number of different types of components.

Abstract: Transceiver and methods are included that are especially suitable for detecting metallic materials, such as metallic mines, within an environment. The transceiver includes a digital waveform generator used to transmit a signal into the environment and a receiver that produces a digital received signal. A tracking module preferably compares an in-phase and quadrature transmitted signal with an in-phase and quadrature received signal to produce a spectral transfer function of the magnetic transceiver over a selected range of frequencies. The transceiver initially preferably creates a reference transfer function which is then stored in a memory. Subsequently measured transfer functions will vary depending on the presence of metal in the environment which was not in the environment when the reference transfer function was determined. The system may be utilized in the presence of other antennas, metal, and electronics which may comprise a plastic mine detector for detecting plastic mines.

Abstract: The variation in properties of a ferromagnetic material with depth below the surface is assessed in a nondestructive fashion using a probe that incorporates an electromagnet. An alternating magnetic field is generated in the electromagnet and so in the object, and a magnetic sensor is arranged to sense a magnetic field due to the electromagnet. Signals from the magnetic sensor are analysed into an in-phase component and a quadrature component, and these are mapped directly into material property and lift-off components; this analysis enables accurate measurements of material property (such as stress) to be distinguished from changes in lift-off. The measurements are repeated for at least five different frequencies of the alternating magnetic field; and the measurements at different frequencies are deconvolved assuming a functional form for the variation of material property with depth, the function having no more than five unknown constants. The stress at depths for example in the range 0.5 mm to 5.

Abstract: Apparatus for detecting a metal object comprises a transmitter for generating a pulsed or an alternating magnetic field in the vicinity of the metal object to be detected and a detector for detecting the secondary magnetic field induced in the metal object by the transmitted magnetic field. The detector measures at least three magnetic field gradient components of at least first order of the secondary magnetic field. The apparatus also comprises a processor for determining at least one of the position or the electro-magnetic cross-section or an estimate of the shape of the metal object from the measured magnetic field spatial gradient components. The processor fits the measured components to dipole, multiple dipole, multipole, or extended source models. In a preferred embodiment, the invention may comprise three or more pairs of gradiometric coils, or other sensing means.

Abstract: A vibrating sample magnetometer controls an electromechanical drive using both ac and dc control and a position sensor. Absolute position sensing is used in a feedback loop to control both an alternating current (ac) drive and a direct current (dc) drive to the electromechanical drive. Improved performance and stability results.

Abstract: An apparatus for detecting the presence or absence of foreign matter in a product is provided which includes a reaction signal generating circuit 2 for outputting a reaction signal associated with the product by detecting a change in pattern of distribution of magnetic fluxes when the product P is passed through an alternating magnetic field; a determining circuit 10 for comparing a value of the reaction signal at a predetermined phase point p1 with a threshold value SH to thereby determine the presence or absence of the foreign matter in the product; and a sensitivity adjusting circuit 12A for adjusting a sensitivity of the reaction signal generating circuit 2 so that the value of a first test reaction signal A at the predetermined phase point p1, which is obtained when a product P added with foreign matter of a minimum size to be detected is passed through the alternating magnetic field, attains a desired level relative to the threshold value SH.

Abstract: In accordance with the present invention there is provided an eddy current probe for the detection of defects within a structure. The probe has a sensing end with a coil disposed therein. The coil is operative to generate an eddy current field within the structure when placed adjacent to the structure. Furthermore, the probe of the present invention includes a metallic shield disposed around the coil and operative to focus the eddy current field within the structure. In order to generate the eddy current field, the coil is in electrical communication with a frequency generator. The frequency generator is operative to generate a high and low frequency signal within the coil in order to enhance detection of defects within the structure.

Abstract: A method and apparatus for the contactless determination of planarity and a ferromagnetic metal strip during transit of the strip through a strip-processing line or cold-rolling line. Hysteresis loops repetitively impressed in the metal strip and the tangential magnetic field strength is measured at a surface thereof and electromagnetic parameters are determined from the time course of the tangential field strength signal. The parameters are functions of the mechanical stress which is evaluated to determine residual intrinsic stress distribution and then the planarity or nonplanarity of the strip.

Abstract: Disclosed is a method of obtaining information in-situ regarding a film of a sample using an eddy probe during a process for removing the film. The eddy probe has at least one sensing coil. An AC voltage is applied to the sensing coil(s) of the eddy probe. One or more first signals are measured in the sensing coil(s) of the eddy probe when the sensing coil(s) are positioned proximate the film of the sample. One or more second signals are measured in the sensing coil(s) of the eddy probe when the sensing coil(s) are positioned proximate to a reference material having a fixed composition and/or distance from the sensing coil. The first signals are calibrated based on the second signals so that undesired gain and/or phase changes within the first signals are corrected. A property value of the film is determined based on the calibrated first signals. An apparatus for performing the above described method is also disclosed.

Abstract: A method for evaluation of an eddy current testing signal is provided. The method includes the steps of generating a feature amount based on a sample eddy current testing signal obtained by measuring a standard specimen, the feature amount including a feature highly correlated to a secondary factor which is other than a depth of the flaw and which affects the waveform of the signal; generating an evaluation parameter by using the feature amount, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to correct answer data on the sample eddy current testing signal; and estimating the depth of a flaw, expressed by an actual measurement eddy current testing signal, by use of the evaluation parameter.

Abstract: A flash phase analysis circuit provides parallel phase channels for simultaneously analyzing a detected signal in each of several phase windows and providing parallel outputs indicating whether a target falls in one of the phase windows. In one implementation, the parallel outputs each drive a segment of an output device to indicate the target type to the user. The flash phase analysis circuit divides a detected signal among the phase windows and then simultaneously compares the measured signal at each phase window with a reference signal. The circuit matches measured data with pre-selected phase characteristics corresponding to known targets in parallel and provides parallel output signals indicating target type.

Abstract: A scanning AC hall microscope and a method which measures the domain pattern of magnetic materials, such as magnetic storage media, by measuring the oscillatory motion of a domain boundary under the influence of an external applied AC magnetic field, which allows a differentiation between domains which are immobile and domains which are mobile.

Abstract: A system for characterizing coatings and substrates of a material under test. A sensor is positioned against a coated sample which is to be measured to obtain phase and magnitude measurements. Penetration depth of the magnetic waves of the sensor is a function of frequency. Measurements are made at each of a plurality of signal frequencies. The measured phase and magnitude data is applied with respect to a frequency independent parameter, such as conductivity, using a grid method. The conductivities of the coating and the substrate are determined by the limits of conductivity with respect to frequency. With the assumed conductivities of the coating and substrate, the sensor is once again placed over the material, and coating thickness and lift-off are determined. By examining the coating thickness versus frequency the accuracy of the measurement can be determined, since actual coating thickness does not vary with frequency in the material.