Abstract: A magnetic body inspection device (100) is provided with a detection unit (1) including a differential coil (12) and a detection signal acquisition unit (21). The differential coil (12) has at least a first receiving coil (121) formed of a planar coil and a second receiving coil (122) formed of a planar coil, the first receiving coil and the second receiving coil being differentially connected. The first receiving coil (121) and the second receiving coil (122) are arranged so that detection surfaces thereof are opposed to each other with a magnetic body (W) interposed therebetween.

Abstract: This wire rope inspection system (100) is provided with a control unit (21) for performing control to inspect a status of a wire rope (101) based on first measurement data (201a) and second measurement data (201b) that differ in the measurement date and time. The control unit is configured to align a waveform of first measurement data and a waveform of second measurement data such that an inspection operation start point of the elevator of the first measurement data and an inspection operation start point of the elevator of the second measurement data coincide with each other.

Abstract: A nondestructive testing method for detecting and distinguishing internal and external defects of a wire rope includes: acquiring a magnetic flux signal and a MFL signal of a detected wire rope; preprocessing the magnetic flux signal and the MFL signal of the detected wire rope; comparing a preprocessed magnetic flux signal and a preprocessed MFL signal with a preset magnetic flux signal threshold and a preset MFL signal threshold respectively, and calculating a defect position; extracting a magnetic flux signal of a defect and an MFL signal of the defect based on the defect position; calculating a defect width of the detected wire rope based on the magnetic flux signal of the defect and the MFL signal of the defect; calculating a defect cross-sectional area loss of the detected wire rope based on the defect width; and determining whether the defect is the internal defect or the external defect.

Abstract: A method includes pulsating a magnetic field at a first location associated with an external surface of a wall containing magnetic material. The method also includes measuring at least one characteristic of the pulsating magnetic field at a second location associated with the external surface of the wall. The at least one characteristic changes based on corrosion on an internal surface the wall between the first and second locations. The magnetic field could be pulsated by applying an AC signal to a conductive coil or by vibrating a magnet. The method could also include analyzing the at least one measured characteristic to identify an amount of the corrosion and/or a change in the amount of the corrosion. Use of the internal surface the wall could be modified based on the amount or change of the corrosion.

Abstract: Tubular member inspection apparatus, systems and methods for inspecting tubulars of a variety of diameters. An EMI inspection shoe includes a flexible, generally arcuate body having a leading end, a trailing end, a non-working major face, and a working major face. The leading end, trailing end, non-working major face, and working major face at least partially define an inspection zone therebetween. One or more magnetic flux detectors are carried by the flexible, generally arcuate body in the inspection zone. One or more pressure actuators removably attached to the non-working face are configured to exert pressure on one or more regions of the flexible, generally arcuate body in the inspection zone during an EMI inspection of a tubular, forcing the flexible, generally arcuate body to contort into a generally contoured shape as it passes over a contoured region of the tubular.

Abstract: High-speed tubular inspection systems include a frame at least one magnetic flux generator contained in a coil annulus and a detector assembly each having inlet and outlet openings for passing a tubular member there through. The detector assembly has one or more magnetic detectors and one or more eddy current detectors configured to be spaced a first distance from the tubular member during an inspection. The detectors are each contained in one or more EMI detector shoes. A conveyor supports the frame and a drive mechanism configured to drive the tubular member through the coil annulus (or drive the coil annulus past the tubular member) at high-speeds.

Abstract: A device for the hot measuring, during rolling, of a transverse size of a metal profile (12) includes a transmission element with at least two sections distinct and spatially separated from each other and disposed along a nominal axis of feed of the metal profile, configured to generate an electromagnetic field with a desired profile of force lines, and a reception element disposed along the nominal axis in a position comprised in the overall longitudinal bulk of the transmission element (14) and configured to detect a signal relating to the variations of the electromagnetic field due to the passage of the metal profile.

Abstract: A method for the hot measuring of a transverse size of a metal profile to obtain a diameter and/or a mean thickness includes providing power with a sinusoidal current having at least two frequencies, a transmission element having at least two sections distinct and spatially separated from each other and disposed along a nominal axis of feed of the metal profile, generating an electromagnetic field with a desired profile of the force lines, and detecting a signal relating to the variations of the electromagnetic field due to the passage of the metal profile through the sections of the transmission element using a reception element having one or more sections distinct and spatially separated from each other and disposed along the nominal axis in a position of the transmission element.

Abstract: The present invention addresses the problem of checking defects of a rail for a vehicle with a high SN ratio. A detection device (2) for generating check data related to the defects of a railway rail RR (rail for a vehicle) is provided with an oscillating coil C1 (211) and an oscillating coil C2 (211) that are disposed on the surface opposite the railway rail RR and generate AC magnetic fields whose directions are opposite to each other, and a receiving coil (212) that is positioned between or in the vicinity the oscillation coils and that outputs a magnetic field waveform based on the magnetic fields received from the oscillating coils as the check data.

Abstract: The present invention quickly carries out quantitative evaluation of a defect of a magnetic member. An inspection probe (100), which includes: a third magnet (4) polarized in a direction intersecting a counter surface facing a magnetic member; a Hall element (11) that detects a density of a magnetic flux passing through the third magnet (4) and the magnetic member, is used to apply, to an output signal from the Hall element (11), an evaluation algorithm which is selected according to whether a defective surface is a front surface or a back surface.

Abstract: A method includes pulsating a magnetic field at a first location associated with an external surface of a wall containing magnetic material. The method also includes measuring at least one characteristic of the pulsating magnetic field at a second location associated with the external surface of the wall. The at least one characteristic changes based on corrosion on an internal surface the wall between the first and second locations. The magnetic field could be pulsated by applying an AC signal to a conductive coil or by vibrating a magnet. The method could also include analyzing the at least one measured characteristic to identify an amount of the corrosion and/or a change in the amount of the corrosion. Use of the internal surface the wall could be modified based on the amount or change of the corrosion. Multiple magnetic fields can be generated at multiple first locations, and the at least one characteristic can be measured at multiple second locations.

Abstract: A radio communication device includes a body structural material such as a metal casing, a planar coil antenna which is disposed inside the body structural material so as to face the body structural material and includes a coil pattern and a coil opening, and a first slit pattern which is provided in the body structural material, intersects the coil pattern at at least two locations on the coil pattern in a plan view, and is not connected to an edge portion of the body structural material. Thus, mechanical strength is ensured, and predetermined communication performance is ensured.

Abstract: This invention relates to inductive inertial sensors employing a magnetic drive and/or sense architecture. In embodiments, translational gyroscopes utilize a conductive coil made to vibrate in a first dimension as a function of a time varying current driven through the coil in the presence of a magnetic field. Sense coils register an inductance that varies as a function of an angular velocity in a second dimension. In embodiments, the vibrating coil causes first and second mutual inductances in the sense coils to deviate from each other as a function of the angular velocity. In embodiments, self-inductances associated with a pair of meandering coils vary as a function of an angular velocity in a second dimension. In embodiments, package build-up layers are utilized to fabricate the inductive inertial sensors, enabling package-level integrated inertial sensing advantageous in small form factor computing platforms, such as mobile devices.

Abstract: A water-chamber working apparatus 1 according to the present invention includes a movable body that can move along a tube plate 12 of a steam generator 10, an extendable member 21 that extends and retracts in a direction in which a first coupling portion 21d approach each other and a direction in which these portions move away from each other, where the first coupling portion 21d is attached to a maintenance hatch 15 via a first joint 23a including two rotation axes intersecting with each other, and the second coupling portion 21e is attached to the movable body via a second joint 23b including two rotation axes intersecting with each other, which are different from the rotation axes of the first joint 23a.

Abstract: An eddy current probe is constructed with four coils in a wheatstone bridge configuration.

Abstract: A monitoring system including rubber magnets 41 to 44 provided inside of a belt 1, and magnetic sensors 51 and 52 provided outside of the belt 1, and magnetic forces generated by the rubber magnets 41 to 44 are detected by the magnetic sensors 51 and 52, thereby detecting a condition of the belt 1, wherein the magnetic sensors 51 and 52 are configured using MI sensors.

Abstract: A wire rope flaw detector includes a magnetizer having a pair of exciting magnets disposed on a back yoke such that polarities thereof are opposite to each other, and forming a main magnetic path in a predetermined segment in an axial direction of a wire rope; and a leakage magnetic flux detection section disposed in the predetermined segment in the axial direction, and detecting leakage magnetic flux generated from a damaged portion of the wire rope. Each of the exciting magnets are formed so as to have a cross-section of a shape that embraces the wire rope when each exciting magnet is cut along a plane perpendicular to the axial direction of the wire rope, and has magnetic orientation, on the cross-section of the exciting magnet, oriented from at least two directions toward the wire rope.

Abstract: Systems and methods for flaw detection and monitoring at elevated temperatures with wireless communication using surface embedded, monolithically integrated, thin-film, magnetically actuated sensors, and methods for fabricating the sensors. The sensor is a monolithically integrated, multi-layered (nano-composite), thin-film sensor structure that incorporates a thin-film, multi-layer magnetostrictive element, a thin-film electrically insulating or dielectric layer, and a thin-film activating layer such as a planar coil. The method for manufacturing the multi-layered, thin-film sensor structure as described above, utilizes a variety of factors that allow for optimization of sensor characteristics for application to specific structures and in specific environments. The system and method integrating the multi-layered, thin-film sensor structure as described above, further utilizes wireless connectivity to the sensor to allow the sensor to be mounted on moving components within the monitored assembly.

Abstract: A pipeline inspection tool includes two pole magnets oriented at an oblique angle relative to the central longitudinal axis of the tool body. An array of sensor coil sets is located between opposing edges of the two pole magnets and oriented perpendicular to the central longitudinal axis. Each sensor coil set includes a transmitter coil and two opposing pairs of receiver coils that are gated to receive reflections from the wall of a tubular member. Because the line of sensor coils is rotated relative to the magnetic bias field, the receiver coils are in-line with, and have the same angular orientation as, the transmitter coil. The tool provides improved sensitivity to small defects, substantial decrease in RF pulser power requirements, full circumferential coverage, self-calibration of the transmitted signals, and less interference between transmitter coils caused by acoustic ring around.

Abstract: A method for monitoring the operation of a metal detection system that comprises a balanced coil system with a transmitter coil that is connected to a transmitter unit, which provides transmitter signals having a fixed or variable transmitter frequency, and with a first and a second receiver coil that provide output signals to a receiver unit. A system adapted to operate according to an exemplary method is also provided. According to one embodiment, a carrier signal having the transmitter frequency and a monitoring signal having a monitoring frequency are provided to a modulation unit that suppresses the carrier signal and provides a modulated monitoring signal, which is supplied to a monitoring coil that is inductively coupled with at least one of the receiver coils, whose output signals are demodulated in a demodulation unit that provides a demodulated monitoring signal, which is compared in phase and/or in amplitude with a reference.

Abstract: An automated, non-destructive anhysteretic magnetization characterization method for studying and modeling soft magnetic materials. This measurement method employs a “reading-waveform” that allows multiple points of reference to be established in tracing out the B waveform. In using the reference values from this waveform, the components of B that cannot be measured directly may be calculated with precision. In turn, the initial magnitude of the B waveform is identified as the unknown component of the anhysteretic state. The processes can be repeated for different values of static fields as well as a function of temperature to produce a family of anhysteretic magnetization curves. The core characterization was performed without physically altering the core, so that the true anhysteretic magnetization curve, and the true B-H loop under applied bias H, is measured.

Abstract: An eddy current probe testing apparatus structured to operate concurrently in a driver pick-up mode and said impedance mode is provided. The eddy current probe has two coils. The eddy current probe testing apparatus also includes a signal producing device, an output device, and a switch assembly. The switch assembly is structured to switch how an input signal from the signal producing device is provided to the two coils.

Abstract: A method for integrating a measurement device for use in measuring a machine component includes providing a coordinate measuring machine (CMM) and combining eddy current (EC) capabilities and CMM capabilities to form an inspection probe. The method further includes installing the inspection probe on the CMM so that the inspection probe measures external boundaries of the machine component with the CMM capabilities and substantially simultaneously measures at least one of internal boundaries, internal defects, surface defects, and material properties of the machine component with the EC capabilities, which are directly linked to actual component dimensional information provided by CMM. The inspection data can be simultaneously linked to and/or displayed with a CAD model to enable a direct comparison between the inspection data and the nominal requirements specified on the CAD model.

Abstract: A method for making eddy current tests on an electrically conducting part (13), in which a sensor moves above this part, uses separate emission/reception functions. The method includes obtaining a first complex voltage curve at the terminals of a reception winding (12), obtaining at least one second complex voltage curve at the terminals of a reception winding, determining at least one given distance that minimizes the modulus of the difference between the first curve and the at least one second curve, calculating the arithmetic mean (d) of the at least one given distance, choosing this arithmetic mean+/?20% as the distance between the two emission and reception windings, and detecting if one or several defects are present in this part.

Abstract: Method and device for nondestructive and noncontact detection of faults in a test piece, or electrically conductive particles in a liquid flow, moving past the device, using eddy currents. The test piece or flow is exposed to periodic alternating electromagnetic fields. A periodic electrical signal is detected by a receiver coil. The receiver coil signal has a carrier oscillation whose amplitude and/or phase is modulated by defects in the test piece or by electrically conducting particles and is digitized. A useful signal is produced from the digitized receiver coil signal, and the useful signal is evaluated with an evaluation unit to detect faults in the test piece or electrically conductive particles. When overdriving of the A/D converter stage by the receiver coil signal is ascertained, a part of the receiver coil signal truncated by the A/D converter stage is reconstructed using a mathematical approximation in the digitized receiver coil signal.

Abstract: A monitoring system including rubber magnets 41 to 44 provided inside of a belt 1, and magnetic sensors 51 and 52 provided outside of the belt 1, and magnetic forces generated by the rubber magnets 41 to 44 are detected by the magnetic sensors 51 and 52, thereby detecting a condition of the belt 1, wherein the magnetic sensors 51 and 52 are configured using MI sensors.

Abstract: A method with separate emission/reception functions for making eddy current tests on an electrically conducting part (13), in which a sensor moves above this part, that comprises the following steps: obtain a first complex voltage curve at the terminals of a reception winding (12), obtain at least one second complex voltage curve at the terminals of a reception winding, determine at least one given distance that minimises the modulus of the difference between the first curve and the at least one second curve, calculate the arithmetic mean (d) of the at least one given distance, choose this arithmetic mean+/?20% as the distance between the two emission and reception windings, and detect if one or several defects are present in this part.

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: An eddy current detection system configured in accordance with an example embodiment of the invention employs a high frequency rotary eddy current probe that is capable of detecting very shallow surface imperfections, including imperfections originating at scribe lines located near lap joints on an aircraft fuselage. The rotary eddy current probe includes a differential sensing coil arrangement surrounded by a reflection coil, both of which are located within the probe tip housing of the rotary eddy current probe. The differential sensing coil arrangement and the reflection coil are positioned off-axis within the rotary eddy current probe. In addition, the rotary eddy current probe employs a partial electromagnetic shield that does not completely surround the differential sensing coil arrangement.

Abstract: An apparatus for inspecting a metallic post contoured in a single dimension for defects. The apparatus has a clamp having at least one jaw with a surface conforming to the contour to the metallic post. The conforming jaw or jaws also have a plurality of eddy current coils and the probe has at least one sensor configured to sense at least one of position or motion.

Abstract: A differential probe is scanned along a stator core tooth portion to detect lamination faults. The probe utilizes two magnetic flux injection yokes arranged side-by-side in relatively close proximity, each yoke having two arm portions and two core-tooth flux-injection surfaces, each yoke being wound with an excitation coil winding and at least one yoke-arm of each yoke having a magnetic flux sensor. Current is supplied to the excitation coil windings on each yoke to inject magnetic flux into the stator core laminations while the probe is moved in a scanning process along the core teeth across the laminations. The magnetic flux differential detected at adjacent regions in the core by flux sensors on each of the two yokes is used to incrementally evaluate the core for laminations faults. The output produced by the differential probe may be converted to a digital signal and provided to a computer system for storage and future analysis.

Abstract: A differential probe is scanned along a stator core tooth portion to detect lamination faults. The probe utilizes two magnetic flux injection yokes arranged side-by-side in relatively close proximity, each yoke having two arm portions and two core-tooth flux-injection surfaces, each yoke being wound with an excitation coil winding and at least one yoke-arm of each yoke having a magnetic flux sensor. Current is supplied to the excitation coil windings on each yoke to inject magnetic flux into the stator core laminations while the probe is moved in a scanning process along the core teeth across the laminations. The magnetic flux differential detected at adjacent regions in the core by flux sensors on each of the two yokes is used to incrementally evaluate the core for laminations faults. The output produced by the differential probe may be converted to a digital signal and provided to a computer system for storage and future analysis.

Abstract: The directed field array comprises a cylindrical solenoid 10 and a base 20 located transverse the solenoid axis 11. An array of mutually spaced apart posts 24 extends from the base 20 such that the magnetic field 22 passes through the base 20 and into the array of posts 24, dividing and focusing the magnetic field into discretized magnetic field divisions 22′ through the several posts. In a first configuration, the base 20 is disposed transverse the end of the coil center or core 12 with the array of posts 24 extending from the base 20 away from the solenoid 10 longitudinally with the solenoid axis 11. In an alternative configuration, at least one base 20″ locates at a solenoid end 30 transverse the solenoid axis 11 with an array of posts 24″ extending radially from the base 20, equally spaced apart circumferentially about the base. Multiple bases are typically aligned with their posts staggered.

Abstract: The directed field array comprises a cylindrical solenoid 10 and a base 20 located transverse the solenoid axis 11. An array of mutually spaced apart posts 24 extends from the base 20 such that the magnetic field 22 passes through the base 20 and into the array of posts 24, dividing and focusing the magnetic field into discretized magnetic field divisions 22′ through the several posts. In a first configuration, the base 20 is disposed transverse the end of the coil center or core 12 with the array of posts 24 extending from the base 20 away from the solenoid 10 longitudinally with the solenoid axis 11. In an alternative configuration, at least one base 20″ locates at a solenoid end 30 transverse the solenoid axis 11 with an array of posts 24″ extending radially from the base 20, equally spaced apart circumferentially about the base. Multiple bases are typically aligned with their posts staggered.

Abstract: An exciting coil is constructed by winding a winding in a groove formed on the outer circumference of a circular ring member, and a detecting coil in the shape of a polygon (such as a triangle and a pentagon) when seen from the front is positioned. One side of the detecting coil is placed in a diameter direction of the exciting coil, inside the exciting coil, and the vertex opposite to the one side is placed apart from the exciting coil so that the detecting coil is orthogonal to the exciting coil. A side surface of the exciting coil on the side opposite to the vertex is placed to face the surface of a test material, and used as a flaw detection surface.

Abstract: A current sensor for an electrical device including a primary circuit in which a primary current flows. A magnetic circuit includes two identical U-shaped elements between which two studs for air gaps are located. A secondary circuit includes two similar coils of a cylindrical shape, mounted in series and encircling the air gaps, wherein these two coils are made in a continuous way with only one winding operation without any electrical connection between both coils. The winding of the primary circuit encircles one of the two coils. The sensor is designed so that it may be adapted to several nominal ranges of primary current by varying the number of passages of the primary circuit between coils, the number of windings of the secondary circuit, and the thickness of the air gaps.

Abstract: The invention relates to a method and an apparatus for measuring properties of a moving web, a sensor (1) being arranged on a first side of the moving web (7), the sensor comprising a differential coil (3), which comprises at least two coils, and a reference plate (4). A sensor plate (6) is arranged on a second side of the moving web (7). Electric current is used to induce a voltage to the differential coil (3). The voltage of the differential coil (3) varies as the web (7) changes the effect caused by the sensor plate (6) to the differential coil. The properties of the web (7) are determined by measuring the voltage of the differential coil (3).

Abstract: This invention prevents the failure of detection for horizontal and oblique lift-offs in a probe for an eddy current flaw detection test. A plurality of probes are provided, and each probe includes four detection coils. Two adjacent eddy current flaw detecting probes commonly own (share) one of the four coils. The detection coils are connected to a bridge circuit for picking up a flaw signal. The detection coils are adjusted so that interlinkage magnetic fluxes generated inside the detection coils by the eddy current become equal. An excitation coil for inducing the eddy current in a test piece by AC driving can be disposed over the detection coils. The center of the excitation coil is positioned on the center axes of the detection coils. An oscillator for applying an AC current to this excitation coil is connected to the coil.

Abstract: An eddy current probe for the nondestructive testing of electrically conductive material parts comprises four identical active elements (10a, 10b, 10c, 10d), at lease in pairs, whose centers are arranged in accordance with a square or a quadrilateral, whose diagonals intersect at right angles and have an intersection point located in the center of one of them. The major axes (18a, 18b, 18c, 18d) of said elements are oriented perpendicular to the plane of the square or intersect at the same point on the normal to the center of the square. The active elements are generally windings. Preferably, opposite windings (10a, 10c and 10b, 10d) of the square are connected pairwise in series, so as to produce magnetic fields, which are summated according to the diagonals of the square and the two pairs are connected to one another according to a differential arrangement or circuit.

Abstract: To provide an effective method of nondestructively and easily judging plasticization of steel used in a real construction. A magnetic sensor 10 is made to scan along the surface of steel to detect a magnetic field caused by a magnetic anisotropy induced by plastic deformation of the steel, and the existence and position of the plasticization is judged from the state of distribution of the magnetic field. As a magnetic sensor, a differential type one comprised of detection coils 10a and 10b, the winding directions of which are opposite to each other, is used to compensate a magnetic field intrinsic to the steel.

Abstract: A thickness gauging instrument uses a flux focusing eddy current probe and two-point nonlinear calibration algorithm. The instrument is small and portable due to the simple interpretation and operational characteristics of the probe. A nonlinear interpolation scheme incorporated into the instrument enables a user to make highly accurate thickness measurements over a fairly wide calibration range from a single side of nonferromagnetic conductive metals. The instrument is very easy to use and can be calibrated quickly.

Abstract: To provide a nondestructive inspection apparatus with a reduced distance between a superconducting magnetic sensor and an object under inspection, a cryostat for cooling the sensor to a superconducting state is provided with inner and outer vessels. The inner vessel has a baseplate on which the magnetic sensor is disposed, and has an inner wall defining a central chamber for containing a refrigerant for cooling the magnetic sensor. The outer vessel has an inner wall defining a central chamber for containing the inner vessel, the magnetic sensor and the stage. A gap between the inner and outer vessels is evacuated to insulate the inner chamber from the ambient atmosphere. To facilitate ease of transferring an object to and from the stage for inspection, a load lock area is provided adjoining the outer vessel.

Abstract: A superconducting loop is formed by two Josephson junctions connected to both ends of a washer coil which serves also as a pick-up coil. The washer coil which is a magnetic field detection portion is constituted by two coils, i.e., a coil having a radius r.sub.1 and a number of turns n.sub.1 and a coil having a radius r.sub.2 and a number of turns n.sub.2 which are in the form of concentric circular loops. The two coils are coupled in opposite directions and are designed so that effective areas n.sub.1 .pi.r.sub.1.sup.2 and n.sub.2 .pi.r.sub.2.sup.2 are equal to each other. Since a magnetic field is directly detected by the washer coil, sensitivity to a magnetic field is enhanced. This makes it possible to obtain sufficient sensitivity to a magnetic field even if the area of the magnetic field detection portion is reduced to improve spatial resolution.

Abstract: In order to enhance the sensitivity of a nondestructive testing system, a pair of superconducting coils are disposed in the same plane such that a current flowing through the respective coils when exposed to a uniform magnetic field cancels out. As a result of this configuration, the detection coils are immune to noise, offset fields or other uniform ambient phenomena. In one embodiment, the nondestructive testing unit includes a plurality of detection coils, a SQUID having a pair of connectors for connection to the detection coils, a probe for supporting the detection coils and the SQUID in a coolant, a cryostat for supporting the probe and for keeping the coolant constant, a controller for processing a signal transmitted from the SQUID, and a display device for displaying the result of the processing. At least two detection coils are disposed in the same plane, are directly connected to the SQUID and are integrated on a semiconductor substrate.

Abstract: Metal detector (1) including an oscillator (10) generates an RF field in the vicinity of the head (2). Two reference signals (13, 14) are generated, one signal (14) being in phase with the oscillator (10) and the other signal (13) being shifted from the oscillator signal by 90.degree.. The signal (8,9) from the receive coils (6,7) is amplified and quadrature demodulated into two signal channels, each channel giving the orthogonal component of the original signal (8,9). The signals of each channel are digitized and read by a microprocessor (37) that controls the amplitude of the balance signals (43, 49). One signal (43) is in phase with the oscillator signal (11) and the second signal (49) is shifted 90.degree. from the oscillator signal (11). Signals (43,49) return to detection circuitry (6,7), maintaining balance on each channel. By monitoring the magnitude of the phase shifted and unshifted signals (49,43), the microprocessor (37) determines the characteristics of the product.

Abstract: An electromagnetic-induction type inspection device for inspecting a test specimen by placing the specimen in electromagnetic fields produced by exciting coils, detecting induction currents from induction coils set in the electromagnetic fields, and analyzing a composite signal composed of the amplitude and phase components contained in a differential current between the induction currents. The composite signal is expressed as a waveform which is displayed on a display unit, so that deformed portions of the waveform, which represent internal defects or other abnormalities in the specimen, can be identified.

Abstract: A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks about circular fasteners and other circular inhomogeneities in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil, The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal.By rotating the probe in a path around a circular fastener such as a rivet while maintaining a constant distance between the probe and the center of a rivet, the signal due to current flow about the rivet can be held constant.

Abstract: A magnetic telescope utilized to detect flaws in underground articles such as underground piping, implements multiple stages in the form of geometric and electronic configurations to enhance noise suppression. The geometric configuration includes a differential configuration of two pair of source coils which generate the magnetic flux, and gradiometers which pick-up the magnetic flux. A superconducting quantum interference device (SQUID) is utilized to detect the magnetic flux. The electronic configuration includes circuitry to adjust the current in the source coil pairs to minimize the signal seen by the SQUID when no underground article is present. The electronic configuration also includes feedback circuitry to feed back magnetic flux to the SQUID based on the signal detected by the SQUID. Combining the geometric and electronic configurations provides enhanced noise suppression so that the SQUID is capable of detecting smaller flaws in the underground piping for the same amount of source magnetic flux.

Abstract: A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil. The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal.The maximum sensor output is obtained when positioned symmetrically above the crack. Hence, by obtaining the position of the maximum sensor output, it is possible to track the fault and locate the area surrounding its tip.

Abstract: A pair of Hall sensors are symmetrically positioned between the poles of a horseshoe magnet. The Hall sensors are mounted in a plane flush with the ends of the magnet faces, and are located equidistant from the centerline of the magnet. A small magnetic object in the field of the magnet, preferably located on the magnet axis, has an induced dipole moment which is detected by the Hall sensors. The small magnetic object dipole field is such that the flux at each Hall sensor is in opposite directions, and by differentially sensing the outputs of the Hall sensors, a signal proportional to the magnetic object is derived. Leakage flux from the magnet as well as the flux of the earth's magnetic field, are in the same direction at both Hall sensors, and their effects are zeroed out by the differential sensing of the Hall sensors' outputs. When the poles of the magnet are drawn across the surface of a non magnetic sheet of conductive material, eddy currents are induced in the sheet by the moving magnetic field.