Abstract: A damage detecting apparatus comprises a magnetic-flux generating unit, a first magnetic-flux detecting element, a second magnetic-flux detecting element and a supporting unit. The magnetic-flux generating unit generates a magnetic flux in an object to be inspected. The first magnetic-flux detecting element is detects a magnetic flux leaking from a circumferential part of the object. The second magnetic-flux detecting element is arranged, opposing the first magnetic-flux detecting element across the object and detects a magnetic flux leaking from any other circumferential part of the object. The supporting unit supports the first and second magnetic-flux detecting elements, enabling the first and second magnetic-flux detecting elements to change in position relative to each other in a diameter direction of the object.

Abstract: An apparatus is provided for sensing anomalies in a long electrically conductive object to be inspected. The object may be a pipeline, or other hollow tube. The apparatus may have a magnetic field generator, and an array of sensors spaced about the field generator. As relative motion in the longitudinal direction occurs between the apparatus and the object to be inspected, the moving magnetic field, or flux, passed from the field generator into the object to be inspected may tend to cause eddy currents to flow in the object. The sensors may be spaced both axially and circumferentially to permit variation in magnetic flux, or eddy current divergence, to be sensed as a function of either or both of axial position relative to the wave front of the magnetic field (or, effectively equivalently any other known datum such as the radial plane of the midpoint of the field generator), and circumferential position about the periphery of the apparatus as measured from an angular datum.

Abstract: A multi-layer eddy current sensor includes a sense coil for detecting an eddy current, and a drive conductor for inducing the eddy current. The drive conductor comprises a substantially straight conducting portion that traverses the entire width of the sense coil.

Abstract: The invention relates to a non-destructive inspection method using eddy currents for detecting flaws in a metal structure (3) by means of an array (5) of coils attached to a surface (31) of said structure (3) comprising activation of the coils, measurement of the electrical signals representative of the eddy currents, and evaluation over time of a variation in the electrical signal of each of the coils (511-536) by taking as a reference an edge effect corresponding to a specific electrical signal emanating from at least one coil installed at the edge of the surface, the level of said variation being indicative of the presence of the flaws in the structure.

Abstract: A method and apparatus for inspecting a metallic structure. A first signal is sent into a first location in the metallic structure and a second signal into a second location in the metallic structure at substantially a same time. A first response to the first signal is received. A second response to the second signal is received. The first response is compared with the second response to form a comparison. A determination is made as to whether an inconsistency is present using the comparison.

Abstract: The disclosure describes methods, devices and tools useful in the non-destructive inspection and the characterization of mechanical damage such as dents in pipelines. Methods, devices and tools described herein make use of a strain severity indication combined with a material loss indication such as magnetic flux leakage to determine whether a dent comprises at least one of a crack, a gouge and corrosion. The characterization of the mechanical damage in dents of pipes may be used to determine whether and when any corrective or preventive action should be carried out.

Abstract: An eddy current probe 1 in accordance with the present invention has a structure in which a cross coil 7 is placed in a predetermined direction relative to permanent magnets 3 and 5 in the following manner. When the probe 1 is erected, the coil 7 is placed between the magnets 3 and 5 so that a direction CD in which the opposing portion 9a (9c) of the first coil 9 is extended intersects with a direction MD in which the magnets 3 and 5 are extended. In the same manner, when the probe 1 is erected, the coil 7 is placed between the magnets 3 and 5 so that a direction CD in which the opposing portion 11a (11c) of the second coil 11 is extended intersects with the direction MD in which the magnets 3 and 5 are extended.

Abstract: Yield stress is an important indicator of the strength of a component such as a pipe section. A method and apparatus for measuring yield stress of components made from magnetic materials is provided. The magnetic permeability of the material is recorded at multiple stress levels below yield establishing a permeability-stress relationship. The yield stress is then estimated as a function of the recorded permeability-stress relationship. The permeability stress relationship may be non-linear for a range of stress levels, achieving a peak permeability response for a stress below yield. The yield stress may be estimated as a multiple of the stress at which the peak permeability response is recorded.

Abstract: The invention concerns structural integrity assessment apparatus for determining stress concentration zones in a structure, such as a pipeline. The apparatus allows particularly to detect defects in buried pipelines using magnetometric surveying where anomalies in the magnetic field around the pipelines are detected. The apparatus has a plurality of triaxial magnetic field sensors, each sensor being arranged to measure magnetic field components in a plurality of directions. A support is provided to maintain said sensors in a predetermined relative spacing and orientation. The support is moveable relative to a structure under assessment in use and may be portable. Three or more magnetic field sensors are provided which may be arranged in a linear, two-dimensional or three-dimensional array. The apparatus may include position determining means, such as a global positioning system (GPS), so that stress concentration zones can be located on the structure.

Abstract: A scanning probe for an industrial nondestructive evaluation (NDE) ultrasound or eddy current scanning system. The scanning probe gathers reflected waveform data indicative of internal characteristics of the test object. The scanning probe also includes a self-contained multi-axis position encoder that correlates both multi-dimensional probe underside translation and rotation motion across the test sample surface with the multi-dimensional spatial location on the test object surface. The position encoder compensates for probe rotation that would otherwise negatively impact probe position determination accuracy. A data acquisition system combines sets of positional and waveform data for processing by an NDE analyzer.

Abstract: An eddy current measuring probe sensor has an exciting portion and a detecting portion. The exciting portion includes a primary exciting portion that includes a main core formed of a cylindrical magnetic body and a main coil that is a solenoid coil wound in a circumferential direction around the main core, and a plurality of secondary exciting portions that include sub-cores formed of cylindrical magnetic bodies that are arranged around the primary exciting portion in a manner such that an axial direction of each of the sub-cores is the same as an axial direction of the main core. The plurality of secondary exciting portions are configured to be able to change the position of each sub-core independently in the axial direction relative to the primary exciting portion.

Abstract: An insertion type eddy current flaw detection probe capable of more accurately detecting flaws in magnetic tubes is provided. A method for inspecting magnetic tubes for flaws with high accuracy is also provided. A eddy current flaw detection probe contains a cylindrical yoke (1), a plurality of detection coils (5) disposed around the central portion of the cylindrical yoke in the direction of a cylindrical axis thereof, first and second inner excitation coils (6) disposed on both sides of the plurality of detection coils in the direction of the cylindrical axis, and first and second permanent magnets (3, 4) disposed around the yoke on both sides of the first and second excitation coils in the direction of the cylindrical axis so that the direction of magnetizations thereof are parallel to the radial direction of the yoke and magnetic poles on the cylindrical yoke side thereof are different from each other.

Abstract: A feed-through coil arrangement for an apparatus that tests long products via eddy current includes an exciter coil arrangement with an exciter coil having a passage opening for the long product, and a receiver coil arrangement around the opening. The receiver coil arrangement includes two segment coil arrangements distributed over the passage circumference, wherein each segment coil arrangement has a detection range covering only a circumferential section of the long product circumference. The segment coil arrangements are distributed over two shells surrounding the opening at different distances to a reference axis. First segment coil arrangements on a first shell are without reciprocal overlapping and second segment coil arrangements on a second shell are without reciprocal overlapping.

Abstract: There is provided a probe apparatus. The probe apparatus has a first end configured to connect to a rotating scanner device. The probe apparatus further has a second end with two or more eddy current elements. The second end further has a positioning mechanism configured to position the two or more eddy current elements against cavity walls of an annular cavity of a structure to be inspected with the probe apparatus, when the probe apparatus is positioned within the annular cavity. The second end further has an aligning mechanism coupled to the positioning mechanism. The aligning mechanism is configured to align the two or more eddy current elements in a perpendicular position with respect to the cavity walls of the annular cavity, when the probe apparatus is positioned within the annular cavity.

Abstract: A system includes at least one strip of ferromagnetic material and a plurality of pulsing/receiving coil circuits. The at least one strip of ferromagnetic material is induced with a bias magnetic field and is coupled to a surface of a structure under test. The plurality of pulsing/receiving coil circuits are aligned with a surface of the at least one strip of the ferromagnetic material. The plurality of pulsing/receiving coil circuits are individually controllable by a number of channels to excite guided waves in the structure under test using at least one of active phased-array focusing or synthetic phased-array focusing of the guided waves.

Abstract: An eddy-current flaw detection method includes a synchronization step (S3, S4) of synchronizing the phase of an exciting voltage applied by coil driving means to an exciting coil for generating an eddy current in a test object with the phase of a driving voltage, higher in frequency than the exciting voltage, applied by device driving means to a magnetoimpedance effect device for detecting the variation of a magnetic field arising in the exciting coil; and a magnetic field detection step (S5) of detecting the variation of the magnetic field arising in the exciting coil due to the eddy current generated in the test object using the magnetoimpedance effect device.

Abstract: A method for monitoring local defects in a rotating engine component such as a gear uses one or more eddy current sensor(s) arranged to interact with the engine component as it is rotating during service. The eddy current sensor(s) may be carried by one or more teeth of a monitoring gear. A device is arranged to measure an output signal from the eddy current sensor(s) resulting from interaction with the rotating engine component. The output signal is processed so as to detect a change in shape of the output signal indicative of a local defect.

Abstract: An excitation device for high-energy tests of stator cores of electric generators or motors is disclosed. The excitation device includes one or more excitation modules. Each excitation module includes an excitation winding and a power supply configured to drive an excitation current through the excitation winding which contributes to the overall excitation of the stator core. The excitation module further includes a capacitor. The power supply of the excitation module acts as current source at its output.

Abstract: The invention herein disclosed provides a 2D coil and a method of using the 2D wound EC sensor for reproducing the Eddy Current Testing (ECT) response of a prior art 3D orthogonal sensor. The 3D orthogonal sensor is conventionally wound onto a 3D core, with at least some of the surfaces being un-parallel to the surface be inspected. Using the herein disclosed 2D configuration allows the use of printed circuit board technologies for the manufacturing of these EC sensors. The herein disclosed method and the associated 2D EC sensors are particularly useful for reproducing the EC effect of conventional orthogonal probe arrays.

Abstract: An eddy current measuring sensor including a probe which is configured as a regular triangle and is provided with an excitation unit for applying a given AC excitation signal to a workpiece and a detection unit for detecting a detection signal occurring in an object to be measured responsive to the applied AC excitation signal, wherein the excitation unit is provided with exciting coils which are arranged on each side of the probe, while the detection unit is provided with detection coils which are arranged at each vertex of the probe.

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: A sensor for use in magnetostrictive testing of a structure. An array of sensor elements is attached to a flexible backing. Each sensor element has a thin strip made from magnetostrictive material, a first coil wrapped around the width of the strip and operable to provide a DC bias magnetic field, and a second coil wrapped around the width of the strip and operable for MsS generation and detection. Typically, the first coils of all strips are electrically connected to each other and the second coils of all strips are electrically connected to each other, to form two separate coil circuits. The probe may be wrapped around the circumference of a cylindrical structure, and used for magnetostrictive testing.

Abstract: An inspection apparatus (100) for monitoring the structural integrity of a pipeline (101) comprising a superconducting electromagnet (102) suitable for generating a magnetic field (106); a cryostat (103) suitable for containing and preserving said superconducting electromagnet (102) at a low temperature; at least two magnetic conveyors (104?, 104?) connected at opposite ends of the cryostat (103) suitable for conveying the magnetic field (106) generated by the superconducting electromagnet (102) to the wall of the pipeline (101) and facilitating the closing of a magnetic circuit; at least one sensor system (105) for revealing the intensity of the magnetic field (106). A method for monitoring the structural integrity of a pipeline (101) using an inspection apparatus (100) according to the present invention.

Abstract: A magnet evaluation device is provided for evaluating a magnet having at least two magnetic pieces bonded to an insulating material sandwiched between two adjacent ones of the magnetic pieces. The magnet evaluation device has an excitation coil and a detection coil. The excitation coil is configured to generate a magnetic field that has a size in a range that corresponds to a region including the insulating material. The detection coil has a coil diameter that is smaller than a length of one of the magnetic pieces in a direction in which the magnetic pieces are aligned.

Abstract: The present inventions provides a magnetizing apparatus 100 for magnetic particle testing of a wheel 7 that includes a hub 71, a plate 72, and a rim 73 in sequence from inward to outward in a radial direction of the wheel. The apparatus includes: a conductor 1 inserted through a bore 711 of the hub 71; and a pair of auxiliary conductors 2 connected to respective opposite end portions of the conductor 1, and so disposed as to face respective opposite side surfaces of the wheel 7, and to extend from the hub 71 to the rim 73 outwardly in a radial direction of the wheel 7, wherein the pair of auxiliary conductors 2 and the conductor 1 are energized with alternating current.

Abstract: An apparatus for estimating a property of an earth formation penetrated by a borehole, apparatus including: a carrier configured to be conveyed through the borehole; a transducer disposed at the carrier and configured to transmit and/or receive electromagnetic energy into and/or from the earth formation to estimate the property; wherein the transducer includes a plurality of inductively coupled elements in a series, each element configured to transmit and/or receive electromagnetic energy and at least a first connection to a first element in the plurality and a second connection to a second element in the plurality with at least one of the first element and the second element being disposed between end transducer elements in the series.

Abstract: A probe for detecting distortions in a material includes a probe body, a ferrite core in the probe body, an excitation coil encircling the ferrite core and adapted to generate eddy currents, further magnetic shielding surrounding the excitation coil, and at least one giant magnetoresistive (GMR) sensor disposed in magnetic field-communicating relationship with the excitation coil and off-center with respect to the excitation coil's axis.

Abstract: Non-destructive localization of open defects in electronic devices is performed with a DC SQUID based RF magnetometer capable of sensing coherent magnetic fields up to 200 MHz and higher. RF magnetic fields (or RF current) images are correlated to conductive paths layout of the electronic device, and the open defect is pinpointed at a location of RF current disappearance on the current image. The bandwidth limitations associated with transmission line delays between SQUID circuit and readout electronic, as well as with near-field coupling between different parts of the measurement scheme, are overcome by superimposing the RF flux emanating from device under study on the modulation flux to produce at the SQUID output a binary phase modulated RF voltage, which is processed to lock the static flux, and to control modulation regime by producing an AC bias for the RF flux.

Abstract: A sensor for use in magnetostrictive testing of a structure. The sensor has a thin ferromagnetic strip with a series of parallel crimps across its width. A first wire coil is wrapped around the width of the strip and along its entire length, such that portions of wire that cross the bottom surface of the strip are located inside the crimps, and portions of wire that are wrapped across the top surface of the strip are between the crimps. The sensor further has a second coil wrapped around the length of the strip, or for pipeline applications, around the pipeline.

Abstract: Aspects of the disclosure provide a method for testing. The method includes determining an electrical characteristic of an integrated circuit (IC), subjecting the IC to a stress test, characterizing the electrical characteristic of the IC subsequently to subjecting the IC to the stress test, and determining a quality attribute of the IC based on a comparison of the respective electrical characteristics of the IC before and after subjecting the IC to the stress test.

Abstract: A non-destructive inspection system that has particular application for inspecting a bore in a valve for defects. The system includes an inspection yoke having a ferromagnetic core, where a first coil is wound around the core in one direction and a second coil is wound around the core in an orthogonal direction so that orthogonal electromagnetic fields can be generated within the bore. A controller provides a current flow through the coils to generate the electromagnetic fields to detect defects in the bore.

Abstract: The present invention provides a method for sensing whether carburization occurs or not on an inner surface of a pipe or tube by an electromagnetic testing, comprising: a first step of inserting a carburized tube P0 into an excitation coil 11 and into a detection coil 12, and determining a value of a parameter K; and a second step of setting conditions of the excitation coil so as to obtain the value of the parameter K determined in the first step, and thereafter, inserting a pipe or tube that is an inspection target into the excitation coil 11 and into the detection coil 12 and sensing whether carburization occurs or not on an inner surface of the pipe or tube based on an output signal outputted from the detection coil 12.

Abstract: In a method for detecting near-surface defects in a test sample consisting at least partly of a ferromagnetic material, a test volume of the test sample is magnetized and scanned for the detection of magnetic leakage fields caused by defects. The test volume is magnetized by means of a magnetic constant field and simultaneously by means of a magnetic alternating field superposed on the constant field. Leakage field test devices suitable for carrying out the method are described.

Abstract: An inspection device that is capable of inspecting all heat-transfer-tube sealing portions in a steam generator and that is also capable of analyzing a defect shape is provided. An inspection device that employs the eddy-current flaw detection method to inspect the presence/absence of a defect in a welded portion (103) between a tube (101) and a tube plate (102) is provided with a main unit (41) that has a circular-column portion (41A), which is inserted into the tube (101), and a flange portion (41B), which is pressed against the tube plate (102), and that is rotatable with respect to the welded portion (103); a probe (42) that is disposed inside the main unit (41), that can be moved close to and away from the welded portion (103), and that detects a defect in the welded portion (103); and a pressing portion (44) that presses the probe (42) toward the welded portion.

Abstract: A dynamically self-adjusting magnetometer is disclosed. In one embodiment, a first sample module periodically generates an electronic signal related to at least one magnetic field characteristic of a monitored environment. A second sample module periodically generates an electronic signal related to at least one magnetic field characteristic of a monitored environment. A summing module sums the absolute value of the electronic signal from the first sample module and the electronic signal from the second sample module. A delta comparator module receives the electronic signals from each of the first sample module, the second sample module and the summing module and compares each of the electronic signals with a previously received set of electronic signals to establish a change, wherein an output is generated if the change is greater than or equal to a threshold.

Abstract: A system for detecting a magnetic flux includes: a magnetic-flux-generating coil having a first and second excitation-track elements extending essentially parallel to a reference plane; a flux-conducting structure for guiding the produced magnetic flux; and a flux-detecting coil having a first detection-track element for measuring at least a portion of the produced magnetic flux, the first detection-track element extending in a first plane defined by the first and second excitation-track elements between the first and the second excitation-track elements. The projection of the excitation-track elements of the flux-generating coil onto a projection plane extending parallel to the reference plane essentially covers the projection of the flux-conducting structure onto the projection plane, at least in the region of the windings of the flux-generating coil.

Abstract: The present invention discloses an eddy current probe and an eddy current inspection device including the eddy current probe for inspection of surface defect of a rotor wheel including a dovetail coupling part in which a hook is formed. The eddy current probe in accordance with an embodiment of the present invention includes: a main body, a contact part coupled to the main body and having a convex part and a concave part formed thereon corresponding to the hook, and an eddy current sensor being coupled to an end part of the convex part of the contact part. Accordingly, the detectability of a defect and the permeation depth can be enhanced, and the inspection procedures can be simplified.

Abstract: An eddy current probe includes an excitation coil for coupling to a low-frequency alternating current (AC) source. A magnetoresistive sensor is centrally disposed within and at one end of the excitation coil to thereby define a sensing end of the probe. A tubular flux-focusing lens is disposed between the excitation coil and the magnetoresistive sensor. An excitation wire is spaced apart from the magnetoresistive sensor in a plane that is perpendicular to the sensor's axis of sensitivity and such that, when the sensing end of the eddy current probe is positioned adjacent to the surface of a structure, the excitation wire is disposed between the magnetoresistive sensor and the surface of the structure. The excitation wire is coupled to a high-frequency AC source. The excitation coil and flux-focusing lens can be omitted when only surface inspection is required.

Abstract: The device comprises a magnetization unit, which generates a constant magnetic field, to which the test specimen (12) is exposed so as to magnetize it. The magnetization unit and test specimen (12) carry out a relative motion to each other, thereby inducing eddy currents in the test specimen (12). The magnetization unit has at least one yoke (10) projecting in the direction of the relative motion. In addition to a probe (14), which is offset toward the back with respect to the magnetization unit in the direction of the relative motion and which is suited to detect damage based on the influence of the damage on the induced eddy current, the device comprises at least one further probe (16) between the yoke limbs of the magnetization unit.

Abstract: The invention provides a drive coil and measurement probe comprising the drive coil. The measurement probes can be used, for example, in in-situ, non-destructive testing methods, also provided herein.

Abstract: The systems and methods of the invention pertain to analyzing steam generator tube data for the detection of wear. Further, the invention is capable of performing a comparison of current tube signal data to baseline or historic tube signal data, e.g., from previous and/or the first, in-service inspection of the steam generator. The systems and methods are automated and can generate results to show potential tube-to-tube contact wear areas as well as the progression of tube-to-tube gap reduction within a steam generator tube bundle. In certain embodiments, the invention is capable of comparing current and historical eddy current data to determine the difference that may be related to degradation or other interested phenomena, and of processing and trending historical comparison results to establish normal variance and detect abnormal variances.

Abstract: To provide a surface property inspection device and surface property inspection method with which the surface treatment condition of treated material such as steel subjected to such surface treatments as shot-peening treatment or heat treatment, nitriding, and the like can be non-destructively and precisely inspected, and which offers a high degree of general purpose application. A surface property inspection device 1 includes an AC power supply, an AC bridge circuit, and a judgment device, and the AC bridge circuit has a variable resistor with a variable split ratio ?, a benchmark detector, and an inspection detector.

Abstract: A facility for generating a detection signal upon the presence of metallic-conductive parts in a conveyed flow that is at least largely non-conductive, in which, for example, an alternating electromagnetic field is established in a section of the conveyed flow to be monitored by means of an alternating current generator and a transmitter coil system, whereby a variation of the signal of said field that is triggered by passage of a part is detected by a receiver coil system and converted into a detection signal by an analytical circuit. The individual components of the system are distributed over separate circuit modules which in turn act in concert by means of a bus system.

Abstract: A method of detecting defects using eddy currents is disclosed. The method comprises: exciting eddy currents in a test material using an eddy current probe driven by a drive signal; detecting induced eddy currents in the test material; converting the detected signal into integer values using an analog to digital converter; and adding or subtracting the generated integer values to or from each of two accumulators, or taking no action, so that one accumulator produces a value proportional to one component of the detected signal and the other produces a value proportional to another component of the detected signal and using these values to detect the presence of a defect.

Abstract: [Problem] In conventional non-destructive inspection devices using magnetism, the subject of inspection was limited to the surface layer of the test object as a result of the skin effect, and it was not possible to perform flaw detection inspection at the interior or reverse surface of thick-structured test objects. [Solution] The effect of the surface effect was eliminated by imparting an external signal canceling the detection output of the test object surface layer from the detection output of a magnetic field resulting from eddy currents induced in the test object. As a result, it has become possible to extract the detection output of the test object interior that had been masked by the detection output of the test object surface layer, and it has become possible to perform thickness inspection and flaw detection of the reverse surface and interior or a test object.

Abstract: A rotary eddy current flaw detection probe device has a plurality of ?-shaped eddy current flaw detection probes attached in a rotating disc for detecting flaws in all directions regardless of the flaw direction. Four ?-shaped eddy current testing probes P11 to P22 are arranged around the rotation center Ds1 of a rotating disc 111 and are embedded in the disc 111. The coil planes of detector coils Ds11 to Ds22 of the testing probes P11 to P22 are parallel with each other, and are perpendicular to the rotation plane of the rotating disc 111. The coil planes of the detector coils incline at an angle ? relative to a line Y passing through the centers Ps11 and Ps12 of the probes P11 and P12. The detector coils Dc11 and Dc12 are cumulatively connected to each other and the detector coils Dc21 and Dc22 are differentially connected to each other.

Abstract: An ultrasonic probe that uses the magnetostrictive effect to generate and detect a surface-coupled guided wave for the purpose of inspecting a thick-walled structure for surface defects. A transmitter sensor and a receiver sensor are especially designed to generate and detect short wavelengths that will couple to only one surface of the plate.

Abstract: A rotating field eddy current probe for sensing flaws in electrically conductive tubing is disclosed. The probe includes two stimulation coils physically arranged at 90 degrees to each other about an axis a current sensing portion. The a first alternating current is applied to one of the stimulation coils at a first phase and a second alternating current is applied to the second of the stimulation coils at a second phase, said second phase being electrically 90 degrees apart from said first phase and creating a rotating oscillating magnetic field.

Abstract: The invention relates to a probe for analysing an assembly of rods including an elongate housing (1) supporting at a first end a permanent magnet (5), the north-south axis of which is parallel to the axis of the rods and, in a position sufficiently separated from said magnet, a set of magnetometers (7) for detecting axial, radial and tangential components of the magnetisation of the rods.

Abstract: There is described a pulsed eddy current sensor for measurement of a lift-off distance over a surface of a metallic substrate (a metallic surface). The pulsed eddy current sensor comprises: a primary excitation coil to which are applied voltage pulses for generating primary magnetic fields, wherein an interaction of the primary magnetic fields with the metallic substrate produces secondary magnetic fields; and secondary pick-up probes, each of the secondary pick-up probes located at a different vertical distance from the metallic surface, the secondary pick-up probes used for measuring the primary and secondary magnetic fields and for producing a differential signal that is representative of the lift-off distance.