Abstract: The sheet resistance meter has: a coil which produces a magnetic field; a sensor head provided to enable the magnetic field to induce eddy currents in a thin film formed on a substrate so that the lines of a magnetic force exerted by the magnetic field extend on one side of the substrate; a control device for detecting the sheet resistance of the thin film according to a variation of the magnetic field caused by the eddy currents; a capacitor for achieving resonance with the coil; and a groove section, a primary air port, an auxiliary air port, and a side air port, provided in the sensor head, for controlling the temperature of the coil. The arrangement stabilizes results of the measurement of a sheet resistance by a sheet resistance meter of a one-sided eddy current detection type when it is used continuously.

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

Abstract: A method and system for identifying thicknesses of inspection samples, such as semiconductor wafers is presented. The method and system includes a probe housing, comprising an eddy current sense coil and a linear motion controller, and a computer that controls the linear motion controller and the eddy current sense coil. The computer may be configured to identify a thickness of the inspection sample by a method comprising the generation of a natural intercepting curve based on resistance and reactance measurements of at least two data points. Then, a plurality of corresponding resistance and reactance measurements of a location on the inspection sample is obtained with the eddy current sensor, where the eddy current sensor makes a first measurement at a first distance from the inspection sample, and makes each of the remaining plurality of measurements at a distance that is incrementally further away from the inspection surface.

Abstract: The thickness of a conductive film formed on a substrate can be measured efficiently at low cost witha film thickness measuring apparatus of the invention, which includes an eddy current coil sensor, disposable at a predetermined position near a conductive film, for generating a predetermined eddy current in the conductive film and for detecting a magnetic field caused by the eddy current. The apparatus also includes a displacement sensor for measuring a displacement between the eddy current coil sensor and the conductive film. The thickness of the conductive film is measured in accordance with a variation in inductance of the eddy current coil sensor and the amount of displacement measured by the displacement sensor.

Abstract: Disclosed is a frequency measuring device capable of accurately detecting an end point of polishing a semiconductor wafer by obtaining a frequency measurement result highly accurately in a short period of time. A device FC for measuring the frequency of a measured signal. Vin comprises a counting section including a number i (i2) of n-nary counters 1−i, a time reference circuit 13 which outputs a time reference signal T, whose duration is t, every time interval p, and a number I of gate circuits G1 to Gi whose outputs are connected to the inputs of the n-nary counters 1-i. The gate circuits receive the measured signal Vin at a first input and receive the time reference signal T at time intervals p at a second input. With this structure, the counting section supplies the frequency measured result of the measured signal Vin every time interval p.

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

Abstract: A method for measuring the thickness of a layer of crud containing ferromagnetic material deposited on nuclear fuel rods using eddy current lift-off (coil-to-conductor spacing) measurement by exciting a probe coil at predetermined frequency which penetrates only into the layer of crud containing the ferromagnetic material.

Abstract: In a method for determining a thickness of a layer of electromagnetically conductive material, the measurement errors resulting from different quality of the basic material are eliminated. For each basic material, one dimensionless characteristic value (K) is ascertained. With the aid of a characteristic calibration curve, each characteristic value (K) can be assigned a correction factor (F), with which the measured value of the layer thickness (DM) can be converted into a real value of the layer thickness (D). Different electrical and magnetic properties, dictated by the different quality of the basic material, can thus be largely eliminated.

Abstract: A method for measuring the thickness of an oxide layer formed on the cladding surface of nuclear fuel rods and underlying a crud layer containing ferromagnetic material using eddy current lift-off measurements by exciting a probe coil at a first frequency which penetrates only into the crud layer and by exciting a probe coil at a second frequency which penetrates the crud layer, the oxide layer and into the cladding of a nuclear fuel rod. By subtracting vectorally the complex impedance resulting from exciting the probe coil at the first frequency from the complex impedance resulting from exciting the probe coil at the second frequency, the thickness of the oxide layer formed on the cladding is measured.

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

Abstract: Apparatus and methods are disclosed which provide increased sensitivity, selectivity and dynamic range for non-contact measurement of actual physical and/or kinematic properties of conducting and magnetic materials. The apparatus and methods are based upon various methods for increasing sensitivity, selectivity and dynamic range through proper construction of a magnetometer sensor and for proper selection of operating point parameters for the application. A measurement apparatus for measuring one or more MUT properties includes an electromagnetic winding structure which, when driven by an electric signal, imposes a magnetic field in the MUT and senses an electromagnetic response. An analyzer is provided for applying the electric signal to the winding structure. A property estimator is coupled to the winding structure and translates sensed electromagnetic responses into estimates of one or more preselected properties of the material.

Abstract: A magnetic gauge for determining vehicle body damage including a circular housing having a front face, a rear face and a hollow interior. The circular housing has a stem portion extending downwardly therefrom. The stem portion has a channel formed therein. The front face has a measuring gauge disposed therein. The measuring gauge includes a needle portion. The needle portion has an inner end. The inner end extends within the hollow interior. A magnet is slidably disposed within the channel of the stem portion of the circular housing. A shaft member is slidably disposed within the hollow interior of the circular housing. The shaft member includes a lower segment slidably disposed within the channel of the stem portion of the circular housing. The lower segment has a lower end secured to the magnet. The shaft member with the inner end of the needle portion whereby upward movement of the shaft member will advance the needle with respect to the measuring gauge.

Abstract: A device is disclosed for inspecting an object of electrically conductive material, in which a non-static-signal transmitter generates an electromagnetic field in the object, and a receiver measures the variations of the eddy current generated by the non-static electromagnetic field and produces a signal representing the decay of the eddy current. The non-static-signal transmitter is provided with at least two laterally spaced-apart emitters for emitting an electromagnetic field, which emitters are, during normal operation, so driven that the resulting electromagnetic field in the central region between the emitters is intensified.

Abstract: An eddy current sensor (1) has at least one measuring coil (2) that can be supplied with an alternating current, and an evaluation circuit (3). The eddy current sensor allows the temperature influences on the impedance of the measuring coil to be reliably compensated with a simple design and an evaluation circuit. For this purpose, the eddy current sensor has a compensating coil (4) which can also be supplied with an alternating current and which is arranged closely to the measuring coil, i.e. in thermal contact therewith, in such a way that the electric fields of compensating coil (4) and measuring coil (2) are orthogonal to each other. More particularly, the measuring coil (2) is in an annular form and the compensating coil (4) is wound around the measuring coil in the form of a torus.

Abstract: A pair of copper coils are embedded in the foil strip. A first coil of the pair generates an electromagnetic field that induces eddy currents on the surface, and the second coil carries a current influenced by the eddy currents on the surface. The currents in the second coil are analyzed to obtain information on the surface eddy currents. An eddy current probe has a metal housing having a tip that is covered by a flexible conductive foil strip. The foil strip is mounted on a deformable nose at the probe tip so that the strip and coils will conform to the surface to which they are applied.

Abstract: A nondestructive method for determining the thickness of a metallic protective layer (2) on a metallic base material (1), characterized in that the thickness of the metallic protective layer (2) is determined by detection of a different type of layer (3) which is situated between the metallic protective layer (2) and the metallic base material (1), by ultrasound, eddy-current or (pulsed) thermography. Consideration may be given to a nonmetallic layer (3) of oxides or carbides, a metallic layer (3) of pure nickel or a layer (3) with depleted Al and Ti content in that region of the base material which is close to the surface. This method can be used for turbine blades which are provided with MCrAlY in order to determine the layer thickness, for example during the test phase of coating, and to avoid the known destruction of the turbine blade, which is labor- and cost-intensive.

Abstract: Apparatus and methods are disclosed which provide increased sensitivity, selectivity and dynamic range for non-contact measurement of actual physical and/or kinematic properties of conducting and magnetic materials. The apparatus and methods are based upon various methods for increasing sensitivity, selectivity and dynamic range through proper construction of a magnetometer sensor and for proper selection of operating point parameters for the application. A measurement apparatus for measuring one or more MUT properties includes an electromagnetic winding structure which, when driven by an electric signal, imposes a magnetic field in the MUT and senses an electromagnetic response. An analyzer is provided for applying the electric signal to the winding structure. A property estimator is coupled to the winding structure and translates sensed electromagnetic responses into estimates of one or more preselected properties of the material.

Abstract: A process for determining a thickness of a layer of electrically conductive material, any measurement errors are converted into dimensionless norm values with the aid of a normalization process. In this conversion, measurement errors, for example due to temperature drift and different electrical and magnetic properties of the base material of the carrying body can be largely eliminated. These norm values are converted into layer thickness values with the aid of a calibration curve.

Abstract: An instrument and method for providing accurate and reproducible measurement of absolute properties of a material under test without using conductivity or crack calibration standards. The instrument has a sensor designed to minimize unmodeled parasitic effects. To accomplish this, the sensor has one or more of the following features: dummy secondary elements located at the ends of a primary winding meandering, setting back of the sensing element from a connecting portion of the primary winding, or various grouping of secondary elements. The sensing elements of the sensor can be connected individually or in differential mode to gather absolute or differential sensitivity measurements. In addition, the instrumentation is configured such that a significant portion of the instrumentation electronics is placed as close to the sensor head to provide independently controllable amplification of the measurement signals therein reducing noise and other non-modeled effects.

Abstract: The change in thickness of a film on an underlying body such as a semiconductor substrate is monitored in situ by inducing a current in the film, and as the thickness of the film changes (either increase or decrease), the changes in the current are detected. With a conductive film, eddy currents are induced in the film by a generating an alternating electromagnetic field with a sensor which includes a capacitor and an inductor.

Abstract: A method for determining and generating a computer generated picture of the pattern of the thickness of a selected layer of a multi-layer coating on a workpiece at selected locations and taken at a plurality of timed segments, by a Pelt Gage.

Abstract: The apparatus enables eddy current inspection of a metal tube having a thin layer on its outside face with magnetic or electrical characteristics that are different from those of the metal in-depth. The apparatus comprises a measurement head having a measurement coil (14) for surrounding the tube and means for powering the coil with voltage at high frequency, greater than 100 kHz, and for analyzing the impedance of the coil. The head contains a magnet (22) surrounding the coil and magnetic flux guides (24) on either side of the coil in the axial direction and co-operating with the magnet to constitute a magnetic circuit that creates a magnetic field whose maximum intensity lies inside the coil and close thereto.

Abstract: The invention relates to a method according to the eddy-current testing principle, and to a device for determining the thickness of an electrically conductive protective layer which is applied to an electrically conductive base material. The electrical conductivities of the protective layer and of the base material are different from each other. An excitation coil through which a high-frequency electric current is passed is brought near to the protective layer, so that an electric eddy current is produced in the protective layer and possibly in the underlying base material. A parameter related to the impedance of a probe coil is determined and is used as a basis for determining the thickness of the protective layer, for example by comparison with known reference values. The frequency of the high-frequency electric current is selected in such a way that the thickness of the protective layer is determined unambiguously for a ratio of the electrical conductivities of between 0.7 and 1.5.

Abstract: Measurement probe (1) is used for measuring thin layers (19) on base material (20) using a magnetic or eddy current process. On probe housing (5) above a stop for guide means (3) with measurement sensor (12) and measurement pole (13) sliding element (2) for measurement sensor (12) is guided to move in the longitudinal axis of probe housing (5) as limited by a stop. Between sliding element (2) and stop (9) on guide means (3) there is first helical spring (4) by which sliding element (2) is elastically supported relative to measurement sensor (12). Between stop (9) on guide tube (3) and lower abutment (30) on probe housing (5) is second helical spring (10) which interacts with first helical spring (4) and elastically supports measurement sensor (12) in the rest state at a distance above opening (5a) for measurement pole (13) in probe housing (5).

Abstract: An openable ring assembly is externally centered around and moved parallel to the centerline of a stationary pipe. As a low-frequency EM source signal is applied to the ring assembly, the time and/or frequency shifts of a detected EM signal from the source signal can be correlated to pipe wall thickness without removal of external pipe insulation and metal cladding, if present. The ring assembly may be opened or expandably segmented to allow pipe thickness detection around obstructions or larger diameter pipe. Centering is preferably accomplished by using rollers circumferentially attached to the ring assembly.

Abstract: Method, applicable to an object consisting of a substrate made of ferromagnetic electrically conductive material covered with a layer of a non-ferromagnetic electrically conductive coating, for measuring the product of the layer conductivity times the layer thickness, consisting in placing at least one inductor producing a variable magnetic field in a space neighboring the object, in measuring, by means of a detector consisting of at least one bounded detection surface, two quantities proportional to the parts of the time derivative of the magnetic flux created in the detection surface concomitantly by the inductor and by the object, in phase and in quadrature with a reference electrical signal, in concomitantly employing two different functions of these two measurements by defining an experimental point by taking these two functions as the two input quantities of a first chart which cannot be reduced to an equivalent chart with a single input, which is independent of the conductivity of the layer and of the

Abstract: The invention relates to a device for measuring the thickness of thin layers in the low micrometer range, having a measuring probe at an end region of a supporting arm, the measuring pole of which probe can be placed on the surface of the layer, having a damping device at the lower end region of the supporting arm, having a bearing device for the supporting arm and having a drive device, which operates using magnetic forces, for the supporting arm, the bearing device comprising a torsion-spring, the two ends of which are each fastened, transversely to the pivot plane, to their own bearing block (32, 33), and the pivoting movement lying at least essentially in the Hooke's range of the torsion-spring (31), and the damping device operating on the principle of eddy-current damping.

Abstract: A modular coating thickness gauge includes a probe which generates a signal representative of coating thickness, a PCMCIA card connected to the probe for converting the signal into a standard PCMCIA output format, and a portable computing unit for receiving the signal via the PCMCIA card. The gauge allows the on-site user to alternately record coating thickness measurement data and descriptive textual or graphical data relating to each coating thickness measurement.

Abstract: A sensor arrangement (1) comprising at least one measuring coil (2), at least one voltage source (3) for the measuring coil (2), and an evaluation unit (4) with means for detecting, processing, and evaluating measured signals. This sensor arrangement (1) is used to measure distances and thicknesses substantially independently of the material involved, without the user having to know the physicomathematical relations between the influencing quantities and the measured values. In order to evaluate the measured signals, the evaluation unit (4) of the sensor arrangement comprises a neural network (5) with an input layer, at least one hidden layer, an output layer, and connection weights for the individual layers. The connection weights are determined and stored in a learning phase by measurements taken on a plurality of different suitable learning objects with known actual values.

Abstract: A method and apparatus for determining the thickness of at least one layer superimposed on a substrate, at least one of the layers or the substrate being a conductor of electricity. The method includes the steps of generating an electromagnetic alternating field in the vicinity of the outer most layer with a coil in order to cause any currents to be generated in the conductor which act upon the alternating field. The frequency of the alternating field is adjusted to at least two different frequencies and is measured at these frequencies. The thickness of the layers is then determined based on the measurements and the electromagnetic properties of the substrate and the layers.

Abstract: A depth measuring device is used for measuring the depth of insulation on an electric conductor travelling along a predetermined path. The device includes a cylindrical magnetizable core (11) which generates a magnetic field having an axis directed to intersect the path. The core (11) is magnetized by an electric coil (12) coupled to the core (11) and the current drawn by the coil (12) will vary with the distance of the conductor from the core (11) and so provides an indication of the distance of the conductor from the core (11). A laser beam (14) is directed along the axis of the core so as to lie coaxial with the magnetic field. A detector (15) detects light reflected from the outer surface of the insulation and so provides an indication of the distance of the insulation from the core (11). An electrical system subtracts the two measured distances from each other to provide an indication of the insulation thickness.

Abstract: A dual-mode coating thickness measuring probe for determining the thickness of a coating on ferrous and non-ferrous substrates. The probe has a first winding assembly including an induction winding and two search or pick-up windings and a second winding assembly including a search winding disposed on a non-magnetic and non-conductive former. A magnetic cylindrical pin of a material with a high resistance to impact and abrasive wear passes through the first and second windings. A conductive non-magnetic coaxial screen through which the pin extends separates the first winding from the second winding. The position of the screen is such that it has a minimal effect on the second winding while shielding its field from the first winding. The first and second windings are connected to signal conditioning circuitry which produces outputs representing the coating thickness measured.

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: A probe holder mounted to a main housing of an electronic thickness gauge, of the type having a remote probe connected to the main housing by an elongate cable, enables the gauge to be used in its initial configuration when the probe is out of the holder and as an integral unit when the probe is positioned in the holder. The holder may be retrofit onto an existing gauge by making it an integral part of a battery cover that replaces an original battery cover. A second embodiment includes a cylindrical remote probe holder having independent, dedicated sensors mounted at its opposite ends to facilitate switching from one type of sensor to another, a third embodiment provides multiple remote probes independently interconnected to the main housing by elongate cables, and a fourth embodiment mounts remote probes in a "V"-shaped housing to enable switching from a first probe to a second by rotating the housing about an axis of rotation.

Abstract: An apparatus for determining paint damage including a magnetic-field responsive sensor and display elements. The sensor signal function of the thickness of the paint on a substrate is fed by a discriminator to one of at least two tracks in relation to the amplitude of said signal. A display element is assigned to each track and in the presence of a signal will display said track.

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 meandering winding magnetometer (MWM) includes a meandering primary winding and at least one sensing winding or coil on a membrane to be pressed against a test surface. The membrane may be supported on a flexible carrier which is translatable into a probe. Abutments in the probe press the carrier against the test surface but allow the carrier and membrane to conform to the test surface. One MWM circuit includes meandering primary and secondary windings. The return leads from the secondary winding return to connector pads in close alignment with the test array, while leads from the primary winding are spaced at least one wavelength from the array. In another MWM circuit, individual sensing loops are positioned within the meandering primary winding. The MWM circuit may be provided on an adhesive tape which may be cut to length.

Abstract: An apparatus for measuring the thickness of a slag layer on a metal melt in a metallurgical vessel comprises a first inductive eddy current sensor which indicates the distance of the apparatus from the metal melt as it is moved toward the melt. A second sensor detects when the apparatus reaches a predetermined distance relative to or contacts the slag layer and triggers the inductive eddy-current sensor when such distance is attained. The sensors are arranged in predetermined spatial relation and the thickness of the slag layer is determined by an evaluation device which analyzes the received signals. The apparatus permits measurement of the thickness of the slay layer without the need of additional equipment (e.g. mechanical lance movement or distance measurement).

Abstract: A modular coating thickness gauge includes a probe which generates a signal representative of coating thickness, a PCMCIA card connected to the probe for converting the signal into a standard PCMCIA output format, and a portable computing unit for receiving the signal via the PCMCIA card. The gauge allows the on-site user to alternately record coating thickness measurement data and descriptive textual or graphical data relating to each coating thickness measurement.

Abstract: The change in thickness of a film on an underlying body such as a semiconductor substrate is monitored in situ by inducing a current in the film, and as the thickness of the film changes (either increase or decrease), the changes in the current are detected. With a conductive film, eddy currents are induced in the film by a generating an alternating electromagnetic field with a sensor which includes a capacitor and an inductor.

Abstract: An apparatus for accurately inspecting an electroconductive film using an eddy current and an apparatus for production of an optical fiber which measures on-line the electrical resistance, which shows the state of formation of the electroconductive hermetic coating of the optical fiber by an electroconductive film inspection method and reflects back the measurement results to the hermetic coating forming conditions. Optical fiber is made up of a core, a cladding, amorphous carbon film or other electroconductive hermetic coating formed on the outer surface of the cladding, and a protective coating. The electrical resistance of the hermetic coating generates an eddy current at the coating, the eddy current generated is detected, and the phase angle of the complex impedance is detected to enable calculation.

Abstract: The change in thickness of a film on an underlying body such as a semiconductor substrate is monitored in situ by inducing a current in the film, and as the thickness of the film changes (either increase or decrease), the changes in the current are detected. With a conductive film, eddy currents are induced in the film by a generating an alternating electromagnetic field with a sensor which includes a capacitor and an inductor.

Abstract: A method and apparatus for checking whether documents have been separated from an opened envelope includes conveying an envelope past an input transducer which measures a characteristic, based on light shown through the envelope, of each individual envelope along a measuring path parallel to the direction of movement of the envelope. From the measured characteristic, a value profile is determined, from which a reference value for each envelope is determined. The value profile is used then to calculate an extreme limit value for each envelope. An envelope-suspect signal is generated if the value profile lies beyond the limit value over a specified minimum substantially continuous measuring distance. The system calculates the values for each envelope, and accordingly, envelopes of greatly diverse characteristics may be reliably checked in random order.

Abstract: A method and apparatus for measuring an anodic capacity of a thermally sprayed coating are described. Eddy current techniques are used to probe the coating and resulting RMS voltages are translated into anodic capacity indications which can be standardized or absolute. Recalibration can be achieved using single point measurement.

Abstract: An improved sensor includes an inductor coil which is formed about a central axis. The inductor coil is configured to provide a magnetic field radially outwardly of the central axis. The monitor circuit monitors changes in the impedance of the coil, to in turn provide an indication of the amount of metal mass radially outwardly of the sensor. The monitor circuit is set to be triggered at a particular amount of metal mass, which would in turn be tailored to the particular application. In one desired application, the sensor is utilized to detect the presence of a nut in a metal plate. Metal plates as are typically utilized with vehicles will often include a number of holes which are to receive nuts. If the nuts are not received in the holes, then that particular metal plate should not be further assembled into the product. One widespread use of such a technique is with the assembly of vehicle bodies. The side sensor will detect the presence of a nut in the hole when positioned within the bore of the nut.

Abstract: A method and system for accurately inspecting an electroconductive film using an eddy current and a process and apparatus for production of an optical fiber which measures on-line the electrical resistance, which shows the state of formation of the electroconductive hermetic coating of the optical fiber by the electroconductive film inspection method and reflects back the measurement results to the hermetic coating forming conditions. Optical fiber is made up of a core, a cladding, an amorphous carbon film or other electroconductive hermetic coating formed on the outer surface of the cladding, and a protective coating. The electrical resistance of the hermetic coating generates an eddy current at the coating, the eddy current generated is detected, and the phase angle of the complex impedance is detected to enable calculation.

Abstract: A method of and an apparatus for measuring the thickness of the overlay clad of the pressure vessel of a nuclear reactor with good accuracy are disclosed. A magnetic yoke having an appropriate length and cross-sectional area of the magnetic path is placed closely in contact with the surface of the overlay clad of the pressure vessel of the nuclear reactor to form a magnetic path by the magnetic yoke and the pressure vessel of the nuclear reactor, the magnetic yoke is magnetized, the distribution of the magnetic field on or near the surface of the overlay clad in contact with which the magnetic yoke is closely placed is measured and the thickness of the overlay clad of the pressure vessel of the nuclear reactor is identified from the medium value or the half value width of the distribution of the magnetic field thus measured.

Abstract: An apparatus for use in determining the thickness of the insulated coating of an electrical cable manufactured in an extrusion process having means for generating an alternating current in the cable core coupled with means for detecting the magnetic field produced by the current flow in the cable such that in combination with a measurement of the distance from the detection means to the coated cable surface, a determination of coating thickness may be made.

Abstract: The invention relates to method and apparatus for measuring and displaying the eccentricity or off-set position with respect to coaxiality of a metallic conductor within an insulating coating during an extrusion process. The measuring apparatus employs a combination of optical and electrically inductive techniques to determine respectively the position of the outer coating of the cable and that of the core within the cable. By relating these positional measurements it is possible to determine the position of the core relative to a desired location namely the coaxial position so that appropriate corrections can be made to the extrusion process to keep the core in that coaxial position.

Abstract: A gauge probe for a handheld combination coating thickness gauge allows the combination coating thickness gauge to measure both nonferrous coatings on ferrous substrate and nonconductive coatings on conductive nonferrous substrate. The gauge probe enables the combination coating thickness gauge to determine automatically, with a single probe, the substrate characteristics, and to effect a measurement of the coating thickness on that substrate. The technique used to measure coatings on a ferrous substrate utilizes a permanent magnet to provide a constant magnetic flux and a Hall sensor and thermistor arranged to measure the temperature-compensated magnetic flux density at one of the poles of the permanent magnet. The flux density at the magnet pole can be related to a nonferrous coating thickness on a ferrous substrate. The technique used to measure nonconductive coatings on a conductive nonferrous substrate utilizes eddy current effects.