Abstract: The present invention relate to a device for the non-destructive evaluation of such structures and components as are in service and which are intended to continue in use for an extended period during which time a number of defects such as residual stress, fatigue, creep or the formation of magnetic phase in non-ferromagnetic steel can develop; in addition to its primary purpose of detecting and/or determining the stated defects in-service steel structures or components, the device of the present invention also possesses the advantage that it can be applied for the sorting and classification of steels of different compositions according to the results of defects detected.

Abstract: The invention provides a method for measuring anchoring strength of liquid crystal through measurement of magnetic-field-induced torque, which, unlike the strong electric-field method or the like, uses a strong magnetic field, is therefore based on a clear principle, does not require bias correction, and enables measurement for liquid crystal of an arbitrary shape, as well as a measurement system for the measuring method.

Abstract: A strain sensor includes a sensor section having a magnetic material provided on one surface of a conductor, the magnetic material being formed integrally with the conductor and having a magnetic strain constant with an absolute value larger than 1×10−7, a fixing mechanism which fixes at least a part of the sensor section, an inductor disposed in a surface side of the sensor section which is opposite the surface on which the magnetic material is provided, the inductor being disposed opposite and away from the sensor section, and a detection unit which detects the amount of deformation of the sensor section caused by stress applied thereto on the basis of a change in inductance of the inductor.

Abstract: A Barkhausen probe includes a magnetizing field generator, a magnetoresistive magnetic field sensor, a direct current power supply for biasing the magnetoresistive magnetic field sensor and signal conditioning electronics. The Barkhausen probe is capable of generating and sensing the Barkhausen noise emanating from the surface of a cyclic magnetized specimen. The conditioned Barkhausen noise output of the signal conditioning electronics is usable as input to various analysis systems where textural analysis of the material can be performed.

Abstract: A sensor for measuring magnetostriction of and/or magnetic thin film is constructed by depositing a thin film nonferromagnetic electrically insulating layer followed by a thin film layer of a sensor material which is piezoresistive and nonferromagnetic. The insulating and the piezoresistive film can be etched into an appropriate pattern and orientation to provide sensitivity to strain in the magnetic film. The magnetostrictive strain in the magnetic film is induced by a known magnetic field which produces a corresponding strain in the piezoresistive film which can be measured as a change in the electrical resistance which can be detected by external probes or other measuring means. The measurement of the magnetostriction can be performed as a part of the manufacturing process for wafers with a plurality of thin film magnetic heads thereon and does not require that the wafers be removed to a laboratory.

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

Abstract: The present, the invention relates to a device for the non-destructive evaluation of such structures and components as are in service and which are intended to continue in use for an extended period during which time a number of defects such as residual stress, fatigue, creep or the formation of magnetic phase in non-ferromagnetic steel can develop; in addition to its primary purpose of detecting and/or determining the stated defects in in-service steel structures or components, the device of the present invention also possesses the advantage that it can be applied for the sorting and classification of steels of different compositions according to the results of defects detected.

Abstract: A temperature sensing apparatus including a sensor element made of a magnetically soft material operatively arranged within a first and second time-varying interrogation magnetic field, the first time-varying magnetic field being generated at a frequency higher than that for the second magnetic field. A receiver, remote from the sensor element, is engaged to measure intensity of electromagnetic emissions from the sensor element to identify a relative maximum amplitude value for each of a plurality of higher-order harmonic frequency amplitudes so measured. A unit then determines a value for temperature (or other parameter of interest) using the relative maximum harmonic amplitude values identified. In other aspects of the invention, the focus is on an apparatus and technique for determining a value for of stress condition of a solid analyte and for determining a value for corrosion, using the relative maximum harmonic amplitude values identified.

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

Abstract: A nondestructive test method determines the degree of metal fatigue of test ferromagnetic construction materials by quantifying a change in effective stress due to aging of the test materials. The disclosed method is to measure the coercive force Hc and the magnetic susceptibility &khgr;H of the test materials at the field of the coercive force Hc. A current tensile stress &sgr; by putting the coercive force Hc and the magnetic susceptibility &khgr;H into the following first equation: &sgr;=a(Hc/&khgr;H)n. where a and n are known constants determined by the internal structure of the test materials. A change in current tensile stress of the test materials is determined by comparing the effective tensile stress &sgr; of the test materials with the initial tensile stress &sgr;0 of the test materials.

Abstract: A method of determining a time-dependent gradient of a shock wave in a percussion or subjected to a percussion load ferromagnetic element and including subjecting the ferromagnetic element to action of a magnetic flux, providing a voltage measuring instrument associated with the ferromagnetic element for determining a change of a magnetic flux velocity, which is determined as a change in a measuring voltage, during a percussion action, and determining the gradient of the shock wave by additive superimposition of the measuring voltage; and a device for effecting the method.

Abstract: A torque sensor having an array of four saturable core magnetic flux detectors arranged in two pairs. Each pair of flux detectors is associated with a pair of magnetoelastic bands. A triangle signal is applied to one end of each pair of flux detectors and an offset correction voltage is applied to the opposite ends. Two amplifiers are associated with each pair of torque detectors and are responsive to the second harmonic of detected flux signals. The signal conditioning electronics provide automatic offset and drift correction.

Abstract: Methods and apparatus for detecting particular frequencies of vibration utilize a magnetically-tunable beam element having a stress-sensitive coating and means for providing magnetic force to controllably deflect the beam element thereby changing its stiffness and its resonance frequency. It is then determined from the response of the magnetically-tunable beam element to the vibration to which the beam is exposed whether or not a particular frequency or frequencies of vibration are detected.

Abstract: Fatigue in a magnetically sensitive detector element (20, 172) can be evaluated using the expression H∞ log(N). Employing this method, measuring changes in magnetization of the detector element (20, 172) permit predicting fatigue with many practical applications.

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

Abstract: A nondestructive method for inspecting steel pipelines for plastically deformed regions caused by mechanical damage to the pipeline. The invention is a method and system that uses nonlinear harmonic detection methods to detect mechanical damage in pipelines. The invention uses a time-varying magnetic field to sense magnetic properties of the pipeline. The odd-numbered harmonic frequencies are detected and their amplitudes are related to the magnetic condition of the material under test to determine areas of mechanical damage. This technique can be used for rapidly surveying stress states in pipelines where nonlinear harmonic sensing devices are attached to a pigging device moving through a pipeline at a relatively high rate of speed.

Abstract: A method and an apparatus are provided for measuring the mechanical properties of ferromagnetic, elongated structures, such as cables, through the measurement of Barkhausen signals. The method comprises creating a magnetic field, that varies as a function of time or of position, and measuring the Barkhausen signals rate as a function of the magnetic field for each section of the structure to be tested. The mechanical properties are determined for each section from the Barkhausen signals relative to it. The apparatus comprises means for generating the variable magnetic field, a plurality of Barkhausen signal sensors distributed along the structure length, and means for comparing the signals relative to each section to be tested.

Abstract: An adhesive member is used to bond one member to another member to form an adhesive layer whose internal defection can be detected by utilizing a magneto-mechanical property of a soft magnetic material. The adhesive member is comprised of a main body formed of an uncured adhesive, and a plurality of soft magnetic materials embedded in the main body and restrained in an external force-applied state after curing of the main body.

Abstract: In a nondestructive method of quantitatively evaluating a degree of plasticity of ferromagnetic materials, a magnetic field of a surface of a ferromagnetic test body is measured using a magnetic sensor, and the surface of the ferromagnetic test body is partitioned into regions corresponding to domains of the ferromagnetic test body. A difference between a maximum value and a minimum value of a magnetic signal corresponding to the magnetic field for each of the domains is calculated as a spatial difference amount. A distribution width of the spatial difference amounts and an amount of residual strain corresponding to an amount of plastic deformation of the ferromagnetic test body is measured. A correlation between the distribution width of the spatial difference amounts and the amount of residual strain is calculated. A degree of plasticity of the ferromagnetic test body in calculated in accordance with the correlation.

Abstract: Apparatus and method for measuring the Barkhausen signal of a moving magnetic film, ribbon or fiber wherein first and second stationary electromagnet coils are arranged and separated by a distance, d, along the path of movement of the film, ribbon or fiber. The first and second coils are energized in a manner to generate first and second opposing DC magnetic fields through which the moving film, ribbon or fiber passes along its path of movement. As the film, ribbon or fiber moves through the first and second opposing magnetic fields at a velocity, v, it experiences one complete cycle of magnetization in a period of time equal to d/v. A stationary third signal pick-up coil is disposed between the first and second coils to detect the Barkhausen signal from the moving film, ribbon or fiber. The pick-up coil typically is disposed midway between the first and second coils where the Barkhausen signal will be approximately maximum.

Abstract: In a method of diagnosing the fatigue life of structural steelwork according to the present invention, a Barkhausen noise measurement is performed under the condition of 5 .mu.m.ltoreq.d.ltoreq.1 mm where d is the detection depth of Barkhausen noise, by using a magnetic head constituted by an air-core coil detection head and a magnetic excitation head obtained by winding a copper wire such as an enameled wire on a U-shaped core made of a soft magnetic material such as a silicon steel sheet or an amorphous magnetic material. The degree of fatigue damage of a target measurement portion is diagnosed using the root-mean-square (RMS) voltage or voltage amplitude value of the Barkhausen noise. According to this method, the degree of fatigue and degradation by stress and strain in the structural steelwork can be accurately diagnosed prior to development of cracking without any limitation on diagnostic locations.

Abstract: A correction winding in which an alternating current flows attributable to magnetic flux generated in an exciting winding when an alternating current is allowed to flow in the exciting winding, is provided for a sensing device. In a state where the characteristics of the sensing device are not changed, electric power is supplied to the exciting winding so that a reference value, which is a digital value of the difference in the potential between the two ends of the correction winding detected by the correction detection circuit, is stored in a RAM of a microcomputer by operating a setting switch, and then divided with a digital value of the difference in the potential between the two ends of the correction winding detected by the correction detection circuit. A value Vso/Vs, which is a result of the division, is used to multiply the digital value of the difference in the potential between the two ends of the detection winding detected by the detection circuit.

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: A method for determining the longitudinal loading acting on a beam, such as a rail of a railway track subjected to longitudinal loading and, in particular, for determining the neutral temperature of railway tracks. The beam is energized longitudinally in the acoustic frequency range, and the level of magnetic Barkhausen noise at the surface of the energized region is measured. Measurements of the magnetic Barkhausen noise are taken for different longitudinal stress states and used for plotting the calibration curve of the magnetic Barkhausen noise as a function of longitudinal stress, the Barkhausen noise being measured at least at three points on the face of the built-in beam, and the calibration curve is used for determining the longitudinal loading on the cross-section in question using weighted averaging. The neutral temperature of the railway track is then calculated considering the modulus of elasticity, coefficient of thermal expansion and temperature of the rail.

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

Abstract: A device for measuring residual stress in ferromagnetic and non-ferromagnetic metal objects. The device having four electrically identical induction coils which form a four terminal alternating current bridge circuit. There is a fine wire shield formed of fingers for shielding the coils from stray capacitance. The bridge having four coil terminals. Two diagonally opposite coil terminals are connected to a variable frequency constant voltage generator. The other two diagonally opposite coil terminals are connected to a low noise broad band preamplifier. The preamplifier amplifies any unbalance in the bridge. There is a double pole double throw switch connected to two coil terminals which are diagonally opposite each other. Connected to the preamplifier is an amplifier. The amplifier is connected to a phase detector which is connected to a computer. The phase detector detects in phase and quadrature component signals.

Abstract: The absolute values of biaxial stresses in a ferromagnetic material (16) are measured using a probe (12) which comprises an electromagnet (26), a sensor (32) for stress-induced magnetic anisotropy (SMA) and a sensor (30) for directional effective permeability (DEP). The DEP sensor (30) enables absolute values of stress to be determined; the SMA sensor (32) enables the directions of the principal stress axes to be accurately determined, and improves the accuracy of the stress measurements.

Abstract: To test coiled tubing, at least one test is performed on a coiled tubing that has been used, such as in an oil or gas well. Performing such test includes obtaining a specific output data event (e.g., a nondestructive evaluation test readout) for the used coiled tubing. The specific output data event is compared with a predetermined sequence of output data events (e.g., a collection of data defining a "lifeline" for the coiled tubing) for determining where the sequence and the specific output data event correspond. A coiled tubing status indication is generated in response to where the specific output data event corresponds with the sequence as a measure of a point in the useful life of the used coiled tubing.

Abstract: A structure of a magnetostrictive shaft applicable to a magnetostriction-type torque sensor and a method for manufacturing the same can achieve a high torque sensitivity. A shaft parent material is made of a non-magnetic austenitic series metallic material (YHD50) and a magnetic thin film is made of a magnetostriction material such as Iron-Aluminium series alloy plasma spray coated on the whole outer peripheral surface of the shaft parent material. In a second embodiment, a mechanical working is carried out for the shaft material on the surface of which the magnetostriction material thin film is coated, the worked shaft material is heated under an inert gas atmosphere, and the heated shaft material is immersed into oil under the inert gas atmosphere to perform the oil quenching.

Abstract: Flux-focusing electromagnetic sensor using a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. A ferrous shield isolates a high-turn pick-up coil from an excitation coil. Use of the magnetic shield produces a null voltage output across the receiving coil in presence of an unflawed sample. Redistribution of the current flow in the sample caused by the presence of flaws, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal.Maximum sensor output is obtained when positioned symmetrically above the crack. By obtaining position of maximum sensor output, it is possible to track the fault and locate the area surrounding its tip.

Abstract: A piezomagnetometer uses a magnetoelectric composite structure, formed by alternating layers of piezoelectric and magnetostrictive material, to convert a fluctuating magnetic field directly to electric current. Strain in the magnetostrictive layers, coming from an ambient magnetic field, stresses piezoelectric layers and drives a polarization current proportional to amplitude of the ambient field. Electrically, the composite is a current source connected in parallel with a capacitor. Its simple and direct operation and solid state sensor enables constructing a small, rugged, inexpensive magnetometer that operates at an ambient temperature with high sensitivity at low power. Multiple piezomagnetometers can be incorporated into a practical detection system capable of operating at ambient temperatures and meeting the limitations presented in civilian and military operations.

Abstract: Both a system and method are provided for mapping the magnitude of residual compressive stresses over the surface of a ferromagnetic machine component, such as a valve ring of the type used in refrigeration compressors. The system includes an eddy current probe having a detection coil for emanating a fluctuating electromagnetic field that shallowly penetrates the surface of the valve ring or other ferromagnetic component, a probe circuit connected to the coil for both conducting a high frequency alternating electric current through the coil and detecting changes in the impedance in the coil, and a scanning mechanism having a turntable for supporting and rotating the component. A support arm positions the coil of the eddy current over a central portion of the valve ring while the ring is rotated by the turntable and changes in coil impedance are detected by the probe circuit.

Abstract: A rail axial-force measuring method and an axial-force measurable rail which eliminate the effects of residual stresses existing in a rail and thus enables an axial force acting on the rail to be measured quickly and accurately are provided. The rail is provided with a stress sensing portion which is magnetized by a magnetizing head, and changes in the magnetization of the stress sensing portion are detected by a detection head as a voltage signal from which an axial force acting on the rail is measured. Preferably, the voltage signal is a Barkhausen noise signal and, also preferably, the stress sensing portion is constructed from a portion formed by first locally heating the rail into a .gamma.-phase region, and then causing cementite to precipitate by heat treatment at a temperature lower than the .gamma.-phase region. The axial-force measurable rail including the above-described stress sensing portion is also provided.

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

Abstract: In measuring a stress of a soft magnetic metal wire, an A.C. magnetic field exceeding a coercive force of the metal wire is applied to the soft magnetic metal wire with a tensile load applied thereto, using an exciting coil, thereby inducing an A.C. electromotive force through a detecting coil. An effective value of one or more higher harmonic wave components including a stress information of the soft magnetic metal wire in the waveform of the A.C. electromotive force is determined as a measurement amount. By taking higher harmonic wave components as an amount in this manner, the stress of the soft magnetic metal wire 4 can be measured correctly.

Abstract: A steel hardness measurement system and method of using same are provided for measuring at least one mechanical or magnetic characteristic of a ferromagnetic sample as a function of at least one magnetic characteristic of the sample. A magnetic field generator subjects the sample to a variable external magnetic field. The magnetic field intensity of the magnetic field generated by the magnetic field generating means is measured and a signal sensor is provided for measuring Barkhausen signals from the sample when the sample is subjected to the external magnetic field. A signal processing unit calculates a jump sum rate first moment as a function of the Barkhausen signals measured by the signal sensor and the magnetic field intensity, and for determining the at least one mechanical or magnetic characteristic as a function of the jump sum rate first moment.

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

Abstract: A novel test method enabling residual stress in non-ferromagnetic metal objects to be reliably measured which requires particular circuit elements in the alternating current bridge circuit being employed for measurement to be environmentally controlled. In doing so, the selected circuit resistor elements are thermally isolated in a manner enabling lift-off impedance values to non-destructively measure near-surface residual stress in the metal object being tested.

Abstract: A sensor circuit has coils 3a, 3b whose inductances change in response to a change in a physical quantity. A drive circuit 4A applies an a.c. drive voltage to the coils. A voltage detector circuit 5 senses the voltage across each coil. A current integration circuit 10 integrates the current through each coil starting at the time of a polarity inversion of the drive voltage, and outputs a control signal C1, C2 until the time the integrated value of the coil current becomes zero. A phase detector circuit 6A detects the coil voltage to generate a detection voltage Vd during the time the current integration circuit outputs the control signal. A smoothing circuit 7 processes the detection voltage to output a mean voltage Vm. The sensor circuit eliminates any adverse effects of the internal resistances of the coils by inverting and offsetting the resistive component of the coil voltage during the detection period.

Abstract: A method and apparatus for analysis of magnetic characteristics of a magnetic device used for designing a magnetic head. The magnetic head has recording and reproducing characteristics and a recording and reproducing apparatus of magnetic characteristics. The apparatus for analysis of magnetic characteristics includes a data input part, a coupled analysis part, and a result output part. The data input part is provided with data related to the characteristics of substances composing the magnetic device, data related to the magnetic device divided into a plurality of parts, data concerning the boundary conditions for analysis of the magnetic device, and data concerning the boundary conditions for analysis of the magnetic field.

Abstract: A magnetostrictive element having a large magnetomechanical coupling factor long its axis, is selected to determine strain by measurement of changes in its electrical impedance along such axis. Such measurement is maximized by generation of current of a predetermined frequency conducted through the magnetostrictive element to correspondingly penetrate the magnetostrictive element to a substantial skin depth.

Abstract: A structure of a magnetostrictive shaft applicable to a magnetostriction-type torque sensor and a method for manufacturing the same can achieve a high torque sensitivity. A shaft parent material is made of a non-magnetic austenitic series metallic material (YHD50) and a magnetic thin film is made of a magnetostriction material such as Iron-Aluminum series alloy plasma spray coated on the whole outer peripheral surface of the shaft parent material. In a second embodiment, a mechanical working is carried out for the shaft material on the surface of which the magnetostriction material thin film is coated, the worked shaft material is heated under an inert gas atmosphere, and the heated shaft material is immersed into oil under the inert gas atmosphere to perform oil quenching.

Abstract: A mechanical sensor, comprising a ferromagnetic layer having magnetostriction, a ferromagnetic layer having magneto-resistance effect, a magnetic field generating means which excites these ferromagnetic layers, and a substrate which supports all these elements integrally, can be attained, which is small, thin, highly sensitive, and is capable of integration, by detecting a change of magnetic flux density passing through the ferromagnetic layers resulting from a change of magnetic properties caused by stress as a change of resistance value arising from magneto-resistance effect. As a result, a small, thin, and highly sensitive mechanical sensor can be provided using stress magnetic effect. Furthermore, based on the anisotropy of detection sensitivity, intensity of the stress along a certain direction can be detected selectively.

Abstract: A length measuring apparatus that uses an ultrasonic magnetostrictive delay line can detect a position with high accuracy by utilizing a reflected wave positively. In a measuring apparatus using an ultrasonic magnetostrictive delay line in which a wave transmitter (4) is disposed at one end of an ultrasonic magnetostrictive delay line (1), and the other end of the ultrasonic magnetostrictive delay line (1) is made an open end, a detecting coil (3) is wound around the outer periphery of the ultrasonic magnetostrictive delay line (1) over the whole area of the measuring range, a magnet piece (2) is disposed so as to become slidable along the ultrasonic magnetostrictive delay line (1) an a position of the magnet piece (2) is measured on the basis of a delay time of a detection pulse (B) produced in the detection coil (3) relative to a drive pulse (A) applied to the wave transmitter (4), a period (T.sub.

Abstract: An arrangement of the magnetic detection and excitation head has an excitation head with a U-shaped excitation core of soft magnetic material forming two legs, each having an end plane facing a surface of a measured object, and an excitation coil wound on the core excitable by a low frequency current; and a detection head with a rod-shaped detection core of non-magnetic or soft magnetic material and a detection coil wound thereon. An end plane of the detection core which is to be close to the surface of the object, and the end planes of the two legs of the excitation core are arranged such that the end plane of the detection core is between the end planes of the two legs and all the end planes are substantially on a common flat plane.

Abstract: In an apparatus and method for generating a signal corresponding to a torque applied to a rotatable shaft according to the present invention, a compensation for a change in temperature causing the change in characteristics of the circuit elements including a magnetostriction shaft is carried out. In a preferred embodiment, a posistor whose resistance value is increased as the temperature is increased with respect to a normal temperature (20.degree. C.) is used for an input temperature sensitive resistor of an inverting amplifier connected to a center tap of a half bridge circuit constituted by a pair of coils constituting a torque sensor having the magnetostriction shaft so that an amplification factor of the inverting amplifier is adjusted so as to accord with the change in the temperature.

Abstract: A compact and solid-state mechanical sensor comprises a magnetic layer having magnetostriction and a planar coil for detecting a mechanical property as a change in impedance. The sensitivity of the sensor is improved with heat treatment to relax the internal stress in the magnetic layer. The magnetic layer 12a of 5 .mu.m of thickness is formed on a titanium substrate 11 of 9.4 ppm/.degree.C. thermal expansion coefficient. The magnetic layer comprises an Fe-based amorphous alloy film prepared with a sputtering method, and it has a composition of Fe 74, Cr 4, Si 13 and B 9 (at %), +22 ppm of saturation magnetostriction constant and 8.0 ppm/.degree.C. of thermal expansion coefficient. An insulator layer 13a made of SiO.sub.x of 2 .mu.m of thickness on the magnetic layer 12a, and a planar coil 14 and input/output terminals 15a, 15b made of aluminum of 2 .mu.m of thickness is formed on the insulator layer 13a.

Abstract: A sensor system including a magnetooptic sensing element, a light source, at least one polarizer and at least one detector disposed about the sensing element. The sensing element has a first characteristic such that the sensing element provides a response to an applied external stress.

Abstract: The magnetic sensor of this invention is characterized by a magnet suspen on a torsion bar or wire and by a tunneling tip separated from one end of the magnet, a gap between the tip and the magnet that is small enough to support a tunneling current, an electrical source for imposing a constant biasing voltage across the gap, an electrical force to maintain the magnet and the tip sufficiently close so that a constant tunneling current is maintained therebetween, a feedback circuit to monitor current changes in the gap that result from rotation of the magnet due to changes in the surrounding magnetic field, and at least one recorder to record changes in the magnetic field.

Abstract: A magnetic inspection probe for use in the planar measurement of magnetic properties in two or more defined directions. The inspection probe includes a cup-shaped outer body, a centrally disposed central core, a field generating power coil, a flux coil for measuring magnetic induction and a plurality of field detection elements disposed in various known orientations. In use, the inspection probe of the present invention permits the detection and measurement of anisotropy of material characteristics in at least two directions across the plane of measurement.