Abstract: An electronic component includes a semiconductor chip with a chip topside, an integrated circuit, and a chip backside. The chip backside includes a magnetic layer. The electronic component further includes a chip carrier with a magnetic layer on its carrier topside. At least one of the two magnetic layers is permanently magnetic such that the semiconductor chip is magnetically fixed on the chip carrier.

Abstract: A sensor package apparatus includes a lead frame substrate that supports one or more electrical components, which are connected to and located on the lead frame substrate. A plurality of wire bonds are also provided, which electrically connect the electrical components to the lead frame substrate, wherein the lead frame substrate is encapsulated by a thermoset plastic to protect the plurality of wire bonds and at least one electrical component, thereby providing a sensor package apparatus comprising the lead frame substrate, the electrical component(s), and the wire bonds, while eliminating a need for a Printed Circuit Board (PCB) or a ceramic substrate in place of the lead frame substrate as a part of the sensor package apparatus. A conductive epoxy and/or solder can also be provided for maintaining a connection of the electrical component(s) to the lead frame substrate. The electrical components can constitute, for example, an IC chip and/or a sensing element (e.g.

Abstract: Techniques for detecting defects in the proximity of a hole of a laminate structure include inserting a generally cylindrical body portion into a hole such that a first coil of wire will reside in a plane substantially parallel to a first electrically conductive layer of the laminate material. A magnetic field produced by the first coil of wire will produce eddy-currents in the conductive layer in the plane of the first conductive layer, but damaged laminate materials will fail to produce similar eddy-currents. As the differences in eddy-currents between damages and undamaged laminate layers can be measured, damage to such laminate materials can be determined.

Abstract: The inventive device for evaluating the sensor signal includes the provider for providing the sensor signal, the processor for processing the sensor signal and for providing an information signal comprising information regarding the amplitude course of the sensor signal and means for comparing the sensor signal to a first and a second comparison value, wherein the first and/or the second comparison value are adjustable based on the information signal such that a difference between the first and the second comparison value comprises a non-linear relation to the amplitude course of the sensor signal.

Abstract: A pressure vessel penetration sidewall adjacent a tube installed in the penetration by a clearance fit is inspected by passing an eddy current probe having a pair of circumferential coils through the tube. Eddy currents are induced in the pressure vessel as the probe passes through the penetration tube and degradation of the pressure vessel adjacent the clearance is determined based upon the eddy currents induced in the pressure vessel by the probe.

Abstract: Described are methods for pressurizing elastic support structures or balloons in sensor probes used for the inspection of components having areas of limited access. When inflated, the balloons press flexible sensors against the surface of the material under test. When deflated, the balloons permit easier insertion of the probes into the component and reduce the mechanical stresses on the sensors, thereby extending the sensor lifetime. By sequentially partially inserting the sensor into a limited access area from either side of the limited access area and scanning in opposite directions, the entire surface of the test material can be inspected.

Abstract: An apparatus for generating and measuring bending vibration in a pipe buried underground or a pipe covered by insulating materials is disclosed. There is provided an apparatus for generating and measuring bending vibration in a non-ferromagnetic pipe without physical contact, comprising: a ferromagnetic strip adhered on a surface of the pipe; a coil wound around the surface of the pipe; two magnets for generating bias magnetic field, applied to the strip and parallel to the strip; a power source for supplying an electric current to the coil; and a measuring unit for measuring variation of voltage across the coil, the variation of the voltage being generated due to a strain according to inverse magnetostrictive effect, the strain being generated due to bending vibration, the bending vibration being generated due to deformation of the strip, the deformation being induced according to magnetostrictive effect as the power source supplies the electric current to the coil.

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: An eddy current inspection apparatus includes a holder for a specimen, a holder for an eddy current probe, and an eddy current instrument operatively joined thereto. The probe holder includes carriages for translating the probe along first and second axes. The probe holder is selectively moved to align the probe with an internal channel of the specimen for sliding movement therealong to conduct eddy current inspection thereof.

Abstract: A sensor assembly for use in a vehicle seat cushion for detecting the presence of an occupant includes a mat adapted to be installed in the vehicle cushion. The mat includes first mounting structure and a first sensor device attached to the mat. A first member has a second mounting structure adapted to be attached to the first mounting structure for attaching the first member to the mat. A second member is movably mounted relative to the first member about an axis. A second sensor device is mounted in the second member.

Abstract: Pressurized elastic support structures or balloons are used to press flexible sensors against the surface a material under test. Rigid support elements can also be incorporated into the inspection devices to maintain the basic shape of the inspection structure and to facilitate positioning of the sensors near the test material surface. The rigid supports can have the approximate shape of the test material surface or the pressurization of one or more balloons can be used to conform the sensor to the shape of the test material surface.

Abstract: In a magnetic sensor (1) including a substrate (10) having a magnetism-sensitive element (11) formed thereon, a hard membrane (14) is formed on the outermost surface, an organic film (13) to relieve the stress caused by the hard membrane (14) is formed under the hard membrane (14), and an inorganic film (12) to relieve the stress caused by the organic film (13) is formed between the organic film (13) and magnetism-sensitive element (11). Also, an intermediate film formed from an element having a large force of bonding to carbon may be formed between the organic film (13) and hard membrane (14). Thus, the magnetic sensor (MR sensor, for example) can be protected against an external shock.

Abstract: A method for inspecting a metallic component comprises providing an inspection standard having an eddy current signature substantially similar to an eddy current signature of the metallic component, wherein the inspection standard body is fabricated from a non-metallic material. The method also comprises inspecting the metallic component with an eddy current probe with reference to the inspection standard.

Abstract: An apparatus for measuring the magnetic field distribution of a magnetic sample includes a magnetic field sensor arrangement having three, orthogonally-disposed, Hall sensors for sensing the magnetic field produced by a magnetic sample at a given location, The sensor arrangement is scanned along a predetermined scan pattern. The apparatus then acquires sampling data from the sensor arrangement, the sampled data providing a representation of the magnetic field distribution of the magnetic sample. The data is preferably acquired by an interface card for a PC, which stores sampled data in the main memory of the PC for data analysis and display.

Abstract: A rotor disk is inspected using an inspection apparatus including an inspection fixture which has a base, and at least one guide extending from the base. Each guide is slidably engagable to one of the rotor slots of the rotor disk and has a guide side shaped to slidably conform to the rotor slot side, and a guide bottom having a guide bottom surface which, in combination with a slot bottom surface, defines an elongated inspection cavity extending parallel to the axis of revolution of the rotor disk. The inspection fixture is mated to the rotor disk such that each guide slides into one of the rotor slots. A sensor apparatus includes a sensor, such as an eddy current sensor, sized to slide into the inspection cavity with a close facing relation thereto, and a sensor drive that moves the sensor parallel to a direction of elongation of the inspection cavity. Inspection is performed by inserting the sensor into the inspection cavity, and sensing the rotor slot bottom using the sensor.

Abstract: An eddy current inspection probe for inspecting a preselected surface. The eddy current inspection probe includes an expandable element at least partially defining an interior space which is expandable by introducing a pressurized fluid into the interior space from a collapsed position to an expanded position for contacting the preselected surface of the component for inspecting the surface. The probe also includes an eddy current array positioned over the expandable element for generating and detecting magnetic fields in the component to inspect the preselected surface.

Abstract: Eddy current inspection of a contoured surface of a workpiece is performed by forming a backing piece of flexible, resiliently yieldable material with a contoured exterior surface conforming in shape to the workpiece contoured surface. The backing piece is preferably cast in place so as to conform to the workpiece contoured surface. A flexible eddy current array probe is attached to the contoured exterior surface of the backing piece such that the probe faces the contoured surface of the workpiece to be inspected when the backing piece is disposed adjacent to the workpiece. The backing piece is then expanded volumetrically by inserting at least one shim into a slot in the backing piece to provide sufficient contact pressure between the probe and the workpiece contoured surface to enable the inspection of the workpiece contoured surface to be performed.

Abstract: An embedded eddy current inspection apparatus includes a substrate having an opening, and a test eddy current coil (“test coil”) affixed to the substrate near the opening. An internally inspected multilayer component structure includes an upper layer, a lower layer, and an eddy current probe embedded between the upper and lower layers. The eddy current probe includes the test coil facing a subject layer selected from the upper and lower layers. A method of inspecting a multilayer component structure includes simultaneously energizing the test coil and a reference eddy current coil (“reference coil”) embedded between the upper and lower layers and facing the subject layer. The reference coil is located in a reference region of the multilayer structure. A test signal from the test coil is compared with a reference signal from the reference coil, to determine whether a flaw is present in the subject layer near the test coil.

Abstract: An eddy current inspection probe for inspecting a preselected surface. The eddy current inspection probe includes an expandable element at least partially defining an interior space which is expandable by introducing a pressurized fluid into the interior space from a collapsed position to an expanded position for contacting the preselected surface of the component for inspecting the surface. The probe also includes an eddy current array positioned over the expandable element for generating and detecting magnetic fields in the component to inspect the preselected surface.

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: An eddy current inspection probe for inspecting a preselected surface at least partially defining an opening in a component. The probe includes a cast core having an exterior surface sized and shaped for receipt within the opening of the component and an eddy current array positioned over the exterior surface of the core for generating and detecting magnetic fields in the component to inspect the preselected surface of the component.

Abstract: An eddy current inspection probe for inspecting a preselected surface at least partially defining an opening in a component. The probe includes a cast core having an exterior surface sized and shaped for receipt within the opening of the component and an eddy current array positioned over the exterior surface of the core for generating and detecting magnetic fields in the component to inspect the preselected surface of the component.

Abstract: A scanning head for eddy-current testing includes a probe coil configuration disposed on a film on a film base. The film base is matched to a shape of an object to be tested. This allows quick, low-interference eddy-current testing. A method for producing a scanning head for an eddy-current test and an eddy-current test method are also provided.

Abstract: An Fe group-based amorphous alloy ribbon having a cross section having a width of from 100 to 900 &mgr;m and a thickness of from 8 to 50 &mgr;m and a magnetic hysteresis loop which exhibits a large Barkhausen discontinuity. The amorphous alloy ribbon is suitable for preparing magnetic markers for use in an anti-theft system and an article surveillance system, and as a pulse generator. A magnetic marker formed from the amorphous alloy ribbon is also disclosed.

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: An eddy current inspection probe for inspecting a preselected surface at least partially defining an opening in a component. The eddy current inspection probe includes a core moveable between a retracted position and an expanded position in which the probe is sized and shaped for at least partially filling the opening and contacting the preselected surface for inspecting the surface. The probe includes a compliant covering positioned over the exterior surface of the core and an eddy current array positioned over the outer face of the covering. Further, the probe includes an element positioned between an exterior surface of the core and an inner face of the covering having a coefficient of friction selected to permit the inner face of the covering to move tangentially with respect to the exterior surface of the core as the core is moved from the retracted position to the expanded position to ensure intimate contact between probe and the preselected surface of the component being inspected.

Abstract: An inspection apparatus includes a component engagement apparatus, a detection apparatus, and a movement apparatus and is controlled by a cam. A drawer is slidably attached to the component engagement apparatus to receive and align a component including a TV-shaped opening. The detection apparatus is sized to receive an eddy current probe and is attached to the movement apparatus with an adjustable fixture. The movement apparatus identifies a relative position of the eddy current probe in relation to the TV-shaped opening being inspected and guides the movement of the detection apparatus.

Abstract: An intermediary device is provided between an eddy current bolt hole inspection machine and an associated eddy current probe to positionally align the probe in each bolt hole to be inspected. A first end of the device is attachable to the eddy current bolt hole inspection machine, and a second end, having a tightening bolt, is attachable to the eddy current probe. A collet associated with the second end of the device secures the probe to the device when the tightening bolt is tightened subsequent to the second end accepting the eddy current probe. An adjustable flange component has a first portion separated from a second portion via a spring wave washer to allow the second portion to move left to right and front to back, relative to the first portion.

Abstract: An electronic autoclave cycle passively records the number of thermal cycles to which an instrument has been subjected in a steam autoclave. When a sterilization cycle has been completed, and the instrument is next energized in use, a microprocessor is employed to read the sensor and record the occurrence of a sterilization cycle. Information as to the cumulative number of cycles through which the instrument has been subjected is stored in a non-volatile memory. This data is suitably displayed on a display panel. The sensor employed uses either the Curie temperature or a temperature near but below the Curie temperature of a ferromagnetic material by first magnetizing the material and then, later, checking its flux density to determine whether a thermal cycle has occurred. In a first embodiment, a Hall effect sensor is used to directly measure the magnetic field strength of the magnetizable material.

Abstract: An eddy current test probe having a flexible sensor assembly for non-destructive testing of conductive parts. The flexible eddy current sensor assembly includes a coil assembly having a drive coil and a receive coil positioned in close proximity to each other to maximize inductive coupling. The drive coil receives an alternating voltage from an alternating voltage source. The receive coil is coupled to a visual display which displays the eddy current signal strength in appropriate units. The coil assembly is formed on a flexible membrane. The flexible membrane allows the coil assembly to contour to the PUT surface. By doing so, surface coupling is not only maintained but maximized between the PUT and the coil assembly which, in turn, improves the induced electromagnetic field. A wear resistant film is formed around the outside of the compliance membrane enclosing the coil assembly.

Abstract: A method for measuring the quantity of a polymeric or pre-polymeric composition within a given volume that includes combining the polymeric or pre-polymeric composition with a plurality of microparticles having a non-ferromagnetic or non-ferrimagnetic core provided with a coating that is ferromagnetic, ferrimagnetic, or conductive, to form an admixture in which the microparticles are substantially uniformly dispersed throughout the composition. The microparticles have a detectable electromagnetic characteristic which correlates with the amount of the composition within a given volume. The electromagnetic characteristic of the microparticles is then measured to determine the quantity of the composition within a given volume.

Abstract: A method for measuring the level of stress in a polymeric or pre-polymeric composition within a given volume that includes combining the polymeric or pre-polymeric composition with a plurality of microparticles having a non-ferromagnetic or non-ferrimagnetic core provided with a coating that is ferromagnetic or ferrimagnetic to form an admixture in which the microparticles are substantially uniformly dispersed throughout the composition. The microparticles have a detectable magnetic characteristic which correlates with level of stress in the composition within a given volume. The change in the magnetic characteristic of the microparticles is then measured to determine the level of stress in the composition within a given volume.

Abstract: An eddy current device for inspecting a component, such as a closed surface area of a gas turbine engine or the like, includes an eddy current array circuit having an active face for positioning on a surface portion of the component during an inspection operation and backing on a surface of the eddy current array circuit opposite to the active face. The eddy current array circuit and backing are disposed over the operating face and expandable sides of an extendible pin. The extendible pin has a slot formed therein with interior side edges which narrow toward the operating face of the pin at a predetermined slope. The expanding pin is positioned to cause the angled sides to mate while engaging the interior angled sides of the round or shaped hole to cause the exterior sides of the expandable pin to expand outwardly a greater distance as the pin is pushed deeper into the hole. This causes the eddy current circuit to conform with the shape of the surface to be inspected.

Abstract: An ac machine monitor, particularly applicable to ac induction motors, provides information for ascertaining the health and condition of the motor. The monitor is self-contained, having its own internal power source, electronics, and sensor suite, and attaches directly to the outer frame of the motor. Sensors disposed within the monitor include a motor frame temperature sensor, flux sensor, vibration sensor, and clock. The flux sensor includes a substantially planar substrate onto which a conductive trace is attached as the flux sensing element. Sensor outputs are processed and analyzed by monitor electronics to determine various life history parameters, including motor speed and load, which are stored in electronic memory. A communications port enables a peripheral device, such as a notebook computer or portable data collector, to communicate with the monitor and download the life history parameters stored in memory.

Abstract: An eddy current probe shaft with probe and drive mechanism attached for measuring integrity of a bolt hole, particularly useful for aircraft bolt holes, includes a continuous helical coil manufactured integrally into a one-piece steel shaft providing flexure in the shaft enabling axial self-alignment even when the shaft is inserted obliquely into a bolt hole. The intact, integrated helical coil of flexible steel provides a constant length probe, effectively noncompressible and nonelongatable, flexible under external bias and with a spring constant sufficient to reliably return the shaft to a straight-axis rest position upon release of the external bias. An eddy current probe with a test coil in a probe head is attached at the shaft distal end for measuring cracks and similar structural anomalies in the bolt hole. A drive mechanism is attached at the shaft proximal end for rotating the shaft and probe in the bolt hole for a circumferential scan of the bolt hole interior surface.

Abstract: A magnetochemical sensor for continuous and in-situ sensing of a given chemical species/stimuli includes two magnetically-soft magnetic film layers and a chemical transduction layer that shrinks or swells in the presence of that given chemical species/stimuli. The magnetic switching characteristics of the sensor are dependent upon the thickness of the chemical transduction layer. A method for remotely interrogating the magnetic switching characteristics of the sensor is also provided. In the method, magnetic flux detecting coils are utilized to monitor the sensor.

Abstract: A measurement system for measuring material deterioration in accordance with a magnetic field of the material in the presence of radiation. The measurement system includes a detection circuit which detects a magnetic field of the material and generates a signal indicative thereof which signal includes noise due to the radiation, a signal processing circuit including semiconductor devices to process the signal generated from the detection circuit and a noise reducing circuit for at least reducing noise in the generated signal which is due to the radiation. The signal processing circuit is installed at a place where a dose equivalent of radiation is equal to or smaller than that of a place where the detection circuit is installed.

Abstract: In an electromagnetic acoustic transducer or EMAT, a spring release mechanism comprises a frame or carriage and, if necessary at least one movement element for permitting movement across a surface of a workpiece. A magnet is movable against the surface past the frame or carriage and a base supports the magnet. The spring is connected between the frame and the base for biasing the base away from the frame to urge the magnet away from the surface.

Abstract: Apparatus for monitoring particles in fluid systems in which a detector has electrical contacts that are bridged by particles captured from suspension in the fluid. Upon detection of a particle, a control microprocessor stores a predetermined quantity of electrical energy on a capacitor, which is then discharged through an inductor to burn off the particle at the detector. The burn-off charge and return lines from the charge storage capacitor are un-grounded, and are connected by respective electronic switches through relay contacts to the conductors connected to the chip detector. The relay contacts are also connected to the inputs of a differential amplifier for detecting presence of a chip bridging the detector contacts and monitoring continuity of the conductors to and from the detector. The relay is powered by system voltage, and in the event of system power failure connects the chip detectors directly to warning lamps on an operator panel.

Abstract: Catheters incorporating an electromagnetic field detection device for use in conjunction with a catheter locating apparatus to determine the position of a catheter without the use of X-rays is disclosed. The electromagnetic field detection device includes a pair of leads incorporated into the wall of the catheter and a coil of fine wire located at the distal end of the catheter. In a closed end catheter embodiment, a core of magnetically permeable material is located inside the coil. In an open ended catheter embodiment the core is either omitted or a hollow core is used. In a Venous catheter embodiment, one way valves are located in the sidewall of the catheter near the catheter's distal end. The one way valves permit the injection of fluid into tissue through the catheter while preventing blood from flowing into the catheter.

Abstract: A catheter apparatus for use in determining the location of a tip of a catheter inside biological tissue is disclosed. The apparatus includes a catheter, a detector positioned within the catheter, and a polyimide sheath containing the detector and forming a detector assembly. The sheath is comprised of a first member, a polyimide layer, and a second member having an undulating outer surface sandwiched therebetween. The detector assembly may be removed from the catheter without damage thereto once the tip of the catheter is in its desired location inside biological tissue.

Abstract: Miniature magnetometer apparatus for use with external equipment in determining a position and orientation of a device located within a magnetic field includes an elongated flexible circuit for connection to external equipment, a substrate at the device with a portion of the flexible circuit secured thereto, and a planar sensor mounted on the flexible circuit at the substrate and connected to the flexible circuit.

Abstract: A structure for a small and durable eddy-current probe for testing of conductive tubes, pipes and apertures in work pieces such as vias in printed circuit boards. A thin, rectangular elastic dielectric printed circuit substrate has sensor conductor loops printed on one side. That dielectric printed circuit substrate is placed on a thin rectangular steel sheet (the probe body) and the substrate and body are rolled into a strong, unitary eddy current probe structure which has the sensor loops 3 safely protected on the interior of the rolled-up probe body 1. The steel probe body cylinder thus formed has an external diameter D and an internal diameter d. The ratio of D/d is, preferably, in a range of 1.4 to 1.6. Bonding pad sites 5 are formed on the elastic substrate, for making electrical connections to the probe. The probe interior may be filled with magnetically conductive material.

Abstract: The monitoring device for structural elements, in particular for tension members of soil or rock anchors, compression members of poles, prestressing elements for prestressed concrete structures and bridge cables has at least one sensor conduit (15) disposed inside or outside of a structural element (1) for receiving at least one sensor (16), wherein the sensor (16) is disposed movably and/or releasably in the sensor conduit (15). An evaluation device (18) determines the presence of corrosion, cracks, overloads, overextensions and tension relaxation from the at least one sensor signal.

Abstract: A device for inspecting a component, such as a dovetail slot of a gas turbine engine or the like, includes an eddy current array circuit having an active face for positioning on the surface of the component during the inspection operation and a backing disposed on a face of the eddy current array circuit opposite to the active face. The eddy current array circuit and the backing are disposed over the operating face and expandable sides of an expandable bar. The expandable bar has a slot formed therein with interior side edges which narrow toward the operating face of the bar at a predetermined slope. An expanding wedge with angled sides is positioned to cause the angled sides to respectively matingly engage the interior sides of the slot to cause the exterior sides of the expandable bar to expand outwardly a greater distance as the wedge is pushed deeper into the slot to cause the eddy current array circuit into conformance with the shape of the surface being inspected.

Abstract: The present invention provides an eddy current sensing device capable of in-situ operation within a high temperature and high vibration environment of a combustion turbine engine. The eddy current sensing device is preferably utilized in an eddy current sensing system for monitoring crack formation and displacement of rotating members of the combustion turbine engine. The method according to the present invention provides inducing eddy currents in the rotating member, detecting the eddy currents, providing a signal indicative of the detected eddy currents, filtering the signal based on the condition to be monitored and evaluating the filtered signal to determine whether the condition, such as the formation of a crack in the surface of the rotating member exists, and if so, determining whether the condition is critical or routine.

Abstract: A support device for a probe for the detection and location of possible faults within a bore. The device forms a simple structure enabling a nonspecialized operator to perform reproducible measurements. The device incorporates a probe-holding spindle equipped at one end thereof with a mechanism for fixing a measuring probe and a spindle support having a longitudinal guidance mechanism for the spindle and a mechanism for angular positioning thereof. The device makes it possible to inspect the bores of a rotor shaft.

Abstract: The present invention comprises a sensing matrix (20) comprised of matrix-arranged sensing units for sensing an object, a driving means (40, 50, 63) which drives the sensing matrix (20) and receives a signal showing a state of each sensing unit, and a detecting means (30) which detects location of the object on the sensing matrix (20) on the basis of the signal received by said driving means. The detecting means (30) includes an offset means (30a) which sequentially updates and memorizes a value of the received signal as an offset value at every sensing unit, an operation means (30b) which operates a change in values between a value of a newly received signal and the offset value before updating, and a comparing means (30c) for comparing the change in values between the two with the set value which is set beforehand for detecting the presence of the object.

Abstract: Disclosed are methods for processing and interpreting data acquired from an eddy current probe array inspection system, based on a background subtraction technique. Test and reference waveform data sets are acquired, and subsequently combined. However, the data sets are first normalized and registered to the same position, registering on characteristic signals produced when scanning over edges. Specific techniques are disclosed for normalizing, correcting for spatial offsets, determining the actual locations of edge signals by peak detection and correlation, and adjusting for variations in the number of points in the test and reference data sets.

Abstract: A method and apparatus for inserting an eddy current hole probe into a hole specimen and automatically moving the probe in two orthogonal (X, Y) directions in response to the impedance change of an eddy current coil located in the probe as a function of distance from the surface of the hole. The probe is centered in the hole by a system controller which operates to minimize the composite deviation value of the coil impedance. The diameter of the hole is then determined from the average impedance measurement. Following this, a plot of the hole eccentricity is generated by determining the impedance deviation from the average coil impedance value as a function of the angular rotation of the probe in the hole. Measurements of the hole eccentricity for a plurality of hole depths provides an indication of the hole eccentricity profile.