Abstract: In a magnetic field measurement apparatus, a light source irradiates a gas cell with linearly polarized light serving as pump light and probe light in a Z axis direction, and a magnetic field generator applies, to the gas cell, a magnetic field Ax which is a time function f(t) having the amplitude A0 taking n fixed values fi (where i=1, . . . , and n), and a magnetic field Ay which is a time function g(t) having the amplitude A0 taking m fixed values gj (where j=1, . . . , and m) in each of X axis and Y axis directions. A calculation controller calculates a magnetic field C (Cx, Cy, Cz) of a measurement region using the X axis and Y axis components Ax and Ay of an artificial magnetic field A, and a spin polarization degree Mx corresponding to a measurement value W? from a magnetic sensor.

Abstract: An RF testing method and system by which a DC measurement pathway can also act like a properly terminated RF pathway. Achieving this requires that the output HI, LO, and Sense HI conductors are terminated in a frequency selective manner such that the terminations do not affect the SMU DC measurements. Once all SMU input/output impedances are controlled, as well as properly terminated to eliminate reflections, the high-speed devices will no longer oscillate during device testing, so long as the instruments maintain a high isolation from instrument-to-instrument (separate instruments are used on the gate and drain, or on the input and output of the device). The output of HI, LO and Sense HI conductors are coupled to various nodes of the DUT via three triaxial cables, the outer shieldings of which are coupled to each other and to an SMU ground.

Abstract: Methods and apparatus for characterizing magnetic properties of materials, such as a material's anhysteretic B-H characteristic or its permeability as a function of B or H. A test apparatus for determining these magnetic properties is constructed to yield a symmetrical field distribution through material being tested to avoid localized saturation within the material. Characterization methods take into account radial variations in tangential field intensities when calculating the magnetic properties. The calculations are obtained as solutions of optimization problems through optimization methods such as genetic algorithms.

Abstract: In A method for measuring a dimensionless coupling constant of a magnetic structure includes the following steps. A step of applying an external vertical magnetic field is performed for enabling magnetic moments of a RE-TM (Rare Earth-Transition metal) alloy magnetic layer of the magnetic structure to be vertical and saturated. A step of measuring a compensation temperature is performed when the sum of the magnetization of the RE-TM alloy magnetic layer is zero. A step of applying an external parallel magnetic field to the RE-TM alloy magnetic layer is performed. A step of adjusting the temperature of the magnetic structure to the compensation temperature and measuring a hysteresis loop of the magnetic structure under the external parallel magnetic field is performed, wherein the inverse of the slope of hysteresis loop is a dimensionless coupling constant.

Abstract: The invention concerns a method for producing an assembly of at least one transmission coil (B1) and one reception coil (B2) for eddy current testing, the reception coil receiving in the absence of fault a complex amplitude signal VR, subject to a variation ?VR in the presence of a characteristic fault to be detected. The method consists in selecting the distance ?ER between the axes of the transmission coil and the reception coil so as to maximize the ratio I?VR/VRI.

Abstract: Probes are electrically connected to a surface of a tunnel junction film stack comprising a free layer, a tunnel barrier, and a pinned layer. Resistances are determined for a variety of probe spacings and for a number of magnetizations of one of the layers of the stack. The probe spacings are a distance from a length scale, which is related to the Resistance-Area (RA) product of the tunnel junction film stack. Spacings from as small as possible to about 40 times the length scale are used. Beneficially, the smallest spacing between probes used during a resistance measurement is under 100 microns. A measured in-plane MagnetoResistance (MR) curve is determined from the “high” and “low” resistances that occur at the two magnetizations of this layer. The RA product, resistances per square of the free and pinned layers, and perpendicular MR are determined through curve fitting.

Abstract: A coil for use in an eddy current sensing probe is formed through depositing film traces. The film traces can be directly deposited. The film traces can be deposited on the outer surface of a core or on ends of the core. The film traces can be deposited onto non-planar surfaces other than cores for the inspection of parts having complex geometries. The coil can be used in a single coil probe or in a probe having a sensor array.

Abstract: Probes are electrically connected to a surface of a tunnel junction film stack comprising a free layer, a tunnel barrier, and a pinned layer. Resistances are determined for a variety of probe spacings and for a number of magnetizations of one of the layers of the stack. The probe spacings are a distance from a length scale, which is related to the Resistance-Area (RA) product of the tunnel junction film stack. Spacings from as small as possible to about 40 times the length scale are used. Beneficially, the smallest spacing between probes used during a resistance measurement is under 100 microns. A measured in-plane MagnetoResistance (MR) curve is determined from the “high” and “low” resistances that occur at the two magnetizations of this layer. The RA product, resistances per square of the free and pinned layers, and perpendicular MR are determined through curve fitting.

Abstract: An IBOC broadcasting receiver that uses two different bit error rates as threshold values in receiving hybrid broadcasting in a simultaneous broadcasting format, and switches between digital broadcasting reception and analog broadcasting reception based on the two threshold values. The IBOC broadcasting receiver counts the number of occurrences of switching between digital broadcasting reception and analog broadcasting reception in a specified period of time, and increases a hysteresis width between the two threshold values when the number of occurrences of switching counted exceeds a specified number.

Abstract: The present invention generally relates to the field of biomolecule detection. More specifically, the present invention relates to compositions, methods and systems for the detection and manipulation of biomolecules using magnetic particles.

Abstract: A pattern recognition system to qualify valid triggering for digital storage oscilloscopes. Valid trigger qualification may be established from recognition of triggering level and interval time information, as well as other pattern-related information, to start or stop waveform acquisition. Trigger qualification may be established from either a pattern match or a mismatch. The trigger recognition system may be further extended to the occurrence of complex signals, such as those associated with television, rotating machinery, or other phenomena occuring in predetermined or known patterns.

Abstract: A geometry for a pickup coil assembly that improves the balance of a hysteresis loop tracer is described. First and second balance coils are placed on either side of a pickup coil. The first and second balance coils are wired in series to form a symmetric balance coil that senses the magnetic H field on either side of the pickup coil. The voltage produced by the symmetric balance coil is subtracted from the voltage produced by the pickup coil. This geometry reduces susceptibility to external electromagnetic fields and also reduces susceptibility to changes in the uniformity of the drive field. Mechanical and thermal stability is improved by physically connecting the balance and pickup coils together. Mechanical and thermal stability is further improved by winding the coils on alumina coil forms.

Abstract: A magneto-optical microscope magnetometer capable of simultaneously measuring a hysteresis loop and activation magnetic moment of a submicrometer-scale local area (about 0.3×0.3 &mgr;m). An electromagnet capable of applying a magnetic field to a magnetic material is attached to a polarizing optical microscope capable of observing a magnetized state of the magnetic material, such that images of the microscope varying with the strength of the applied magnetic field are grabbed in real time by a charge coupled device camera and then analyzed. The magneto-optical microscope magnetometer can measure a hysteresis loop and activation magnetic moment in a submicrometer-scale local area observed by the polarizing optical microscope. Further, the magneto-optical microscope magnetometer can measure hysteresis loops and activation magnetic moments simultaneously with respect to all CCD pixels of the camera and observe coercivity and activation magnetic moment distributions of the entire magnetic material.

Abstract: This invention is a method for nondestructively determining the deterioration of determining ferromagnetic materials by quantifying the change in brittleness with aging of the materials. This invention supposes acquirement of an embrittlement coefficient b by measuring a magnetic susceptibility &khgr;b of ferromagnetic materials under a magnetic field having a specified intensity H. And the coefficient b of the ferromagnetic materials is calculated by putting the intensity H and the susceptibility &khgr;b into an equation: b=&khgr;bH2. By the coefficient b, a correlation between the coefficient b and a referenced embrittlement factor of materials like said determining materials is obtained previously. Said coefficient b of said determining materials in the initial and the deteriorated states is acquired. The factor corresponding to the coefficient b is obtained from the correlation. It is possible to quantify the change by comparing the values of the factor in the initial and deteriorated states.

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 is provided for determining magnetic characteristics of an electrically controlled solenoid. The method includes providing an electronically controlled solenoid having an armature, a stator and a coil operatively associated with the stator. The armature, stator and coil define a magnetic circuit. The armature is spaced from the stator to define an air gap between the armature and the stator. Current to the coil is ramped in a generally linear manner over a period of time to define a known current curve. A resulting rate of change of flux in the magnetic circuit is observed and recorded at certain points along the current curve. In accordance with another aspect of the invention, flux in the magnetic circuit is ramped in a generally linear manner over a period of time to define a known flux curve. A resulting current in the coil is observed and recorded at certain points along the flux curve.

Abstract: A method and apparatus for determining remanence and coercivity of high strength rare earth magnets, without full determination of their hysteresis characteristics and subsequent computation, enables high speed, high throughput testing of such magnets in a production facility. The magnets are first fully magnetized by capacitor discharge through a pulsing magnetizing coil, if not already fully magnetized, and their remanence can be noted at zero applied field. Then the magnets are progressively demagnetized, again by capacitor discharge through a pulsing coil, and, with the state of magnetization of the magnets and the strength of demagnetizing field continuously monitored, note is taken of the strength of the demagnetizing field when the magnetization of the magnet is reduced to zero. Based on this sole measurement, the coercivity of the magnet is derived.

Abstract: A high frequency magnetic properties measuring system is used for measurement of high frequency magnetic properties, for example high frequency core-loss and magnetic hysteresis curve (coercivity force, magnetic flux density, permeability) in soft magnetic materials such as ferrites, permalloy and amorphous magnetic cores used in inductors, transformers and filters of various electric and electromagnetic systems and devices such as computers and multimedia devices. A digital oscilloscope is operated as a waveform detection unit for measuring magnetic fields and magnetic flux density. A signal generator and a power amplifier are operated as a signal input unit. The digital oscilloscope and the signal generator are remotely controlled through a General Purpose Interface Bus by the computer. The high frequency magnetic properties are measured by remote control and the resulting data can be outputted and stored by the computer.

Abstract: A method of testing a magnetic head with a spin-valve MR element which includes at least a pinned layer, a free layer and a non-magnetic layer for magnetically separating the pinned layer and the free layer. The method includes a step of measuring an output voltage of the spin-valve MR element under application of an external alternating magnetic field to the magnetic head in a direction parallel to a magnetization direction of the pinned layer, a step of obtaining a .rho.-H loop characteristics of the spin-valve MR element from the measured output voltage, and a step of judging pinned direction of the spin-valve MR element in accordance with a polarity of an inclination of the obtained .rho.-H loop characteristics.

Abstract: A process is presented for the direct determination of characteristic magnetic values of thin magnetizable layers, in which an element creating a magnetic field creates the magnetization of a part surface in such a way that the thin magnetizable layer, the element creating the magnetic field, and a magnetic field sensor are located in a relative position of rest to one another. The magnetic field sensor is then positioned opposite the magnetized part surface by a relative movement of the element creating the magnetic field, the magnetic field sensor, and the thin magnetic layer. During the subsequent measurement of the magnetization of the part surface, the thin magnetic layer, the element creating the magnetic field, and the magnetic field sensor are in a relative position of rest to one another.

Abstract: The invention is an apparatus for controlling an electrical heating element to control a cooking temperature of a cooking pot and contents therein.

Abstract: A measuring circuit obtains desired characteristic values of a device under test by accurately measuring a voltage and a current. Errors are eliminated that originate from the transmission characteristics of cables used in measurements at high frequencies and measurements using long cables. The errors are eliminated by connecting resistors that are equal in resistance to the characteristic impedance of cables, to the inputs of the cables which connect the device under test to a measuring device.

Abstract: A fluxmeter includes an application unit for applying a magnetic field, a superconducting quantum interference element and a flux transmitting circuit. The flux transmitting circuit includes a pickup coil formed of a superconducting print coil and a core for the pickup coil. The core is formed of a soft magnetic material. The core serves to suppress the leakage of magnetic flux to magnetically couple the pickup coil and the superconducting quantum interference element efficiently to improve the sensitivity and resolution of the fluxmeter. The pickup coil may be manufactured by photolithography, sputtering, laser beam deposition, MBE deposition, MOCVD or spray pyrolysis.

Abstract: A multiparameter magnetic imaging system and method to be used in the localized measurement of the magnetic properties of a material and the display of those properties in the form of a false color image indicating the occurrence of those properties across the surface of a sample specimen. The system includes an inspection probe to measure certain magnetic parameters across the surface of the specimen and means to determine a multiplicity of magnetic property values based on the measured data. The system also includes a visual display system which selectively displays the data relating to the determined magnetic properties in the form of a false color image indicating the presence and variation of these magnetic properties across the specimen surface.

Abstract: Apparatus for measuring a hysteresis characteristic of magnetic material, dielectric material or the like in a high frequency range without using a high-speed A/D converter. A current having a predetermined frequency is applied to an object being examined 4 and the magnetic field and magnetic flux density in the object 4 are detected. The detection signals are successively subjected to frequency conversion with predetermined frequencies corresponding to a fundamental wave and harmonic waves by mixers 17, 18. The frequency-converted signals are input to bandpass filters 19, 20. The output signals of the bandpass filters, which are signals of an intermediate frequency, are converted to digital signals by A/D converters 25, 26, the apparatus thereby detecting the fundamental wave component and each higher harmonic component.

Abstract: Strain within a substrate is measured by attaching thereto a magnetic circuit comprising a magnetostrictive, soft ferromagnetic element, and sensing a change in the coercive field of the element caused by strain therewith.

Abstract: Apparatus for measuring hysteretic properties of thin film recording disks is provided which comprises a magnetic field generator for magnetizing a spot on a piece of magnetic material to be tested. The magnetized spot is moved past a stationary Hall effect sensor which detects the magnetic flux being emitted from the magnetized spot. The process of magnetizing and detecting the flux emitted from the same spot is repeated at different magnetization levels to provide a set of automatic measurements that are recorded in a memory of a controller processor. An analysis of the recorded data permits the automatic computation of residual flux, remanent coercivity, switching field distribution as well as other hysteretic properties.

Abstract: On the basis of a finding that a magnetic hysteresis of a metal material, among magnetization characteristics changing with secular degradation of the metal material, shows a clear correspondence with the degree of degradation of the metal material, a change in such a magnetization characteristic is measured to estimate the degree of secular degradation of the metal material, In a typical embodiment, a superconducting quantum interference device is used to detect the magnetization characteristic of a measuring object. According to the present invention, the degree of embrittlement of a metal material used in an environment of high temperatures can be quickly detected in a non-destructive fashion so that the danger of brittle fracture of the metal material can be reliably prevented.

Abstract: In a process and an apparatus for determining the coercive field strength and the maximum pitch of the hysteresis cure in set-up techniques a test body is magnetized in a magnetic field of an exciter coil fed with an alternating current, as the hysteresis curve of the test body is traversed a number of times with the frequency of the alternating current and the tangential field strength on the test body surface generated by the exciter coil is detected continuously with the aid of a magnetic field strength sensor during the traversing of the hysteresis curve. From a harmonic analysis of the time course of the tangential field strength within one period there is calculated a distortion factor for the determination of the maximum pitch of the hysteresis curve.

Abstract: A multiparameter magnetic inspection system for providing an efficient and economical way to derive a plurality of independent measurements regarding magnetic properties of the magnetic material under investigation. The plurality of transducers for a plurality of different types of measurements operatively connected to the specimen. The transducers are in turn connected to analytical circuits for converting transducer signals to meaningful measurement signals of the magnetic properties of the specimen. The measurement signals are processed and can be simultaneously communicated to a control component. The measurement signals can also be selectively plotted against one another. The control component operates the functioning of the analytical circuits and operates and controls components to impose magnetic fields of desired characteristics upon the specimen.

Abstract: Measurement of a physical property such as coercive force of a member to be inspected is performed at a plurality of locations in one region of the member. Similar measurement is performed in a plurality of different regions of the member and a maximum or minimum value (extreme value) is determined for each of the regions. On the basis of the extreme values thus determined, a recurrence period is determined in accordance with an extreme value statistic theory with the aid of a computer, whereon an estimated maximum value of the physical property of the member as a whole is determined from the recurrence period. On the basis of the estimated maximum value, the degree of deterioration of the member is predicted by the computer by consulting the data indicating the previously determined relation between the physical property and the degree of deterioration.

Abstract: A magnetic domain strain gage and method of digitally measuring strain or fatigue within a ferromagnetic material by measuring the time required for an increasing magnetizing force to cause magnetic domains to flip orientation in a ferromagnetic material as a function of strain or stress within the material. The magnetic domain's maximum rate of flip is measured as a time differential by a high frequency digital oscillator which provides a digital signal indicative of the strain thereby providing increased compatibility with digital data acquisition systems and having a superior signal to noise ratio in comparison with present low signal level analog resistance strain gages.

Abstract: A magneto-optic Kerr effect hysteresis loop measuring apparatus is provided which employs a pair of pole-pieces of the same magnetic polarity providing a high and uniform magnetic field strength in the gap between the oppositely disposed faces of the pole-pieces. The spot on the product which is to be nondestructively tested is placed in the gap between the pole-pieces in a region of uniform saturating magnetic field. A laser beam having a high polarization ratio is directed along an incident path with a spot on the surface of the product to be nondestructively tested, and a reflected beam is processed in a Kerr effect detector to provide hysteresis loop data. This data is capable of providing information sufficient to determine the squareness of the hysteresis loop and the coercivity of high coercivity material being nondestructively tested.

Abstract: The manufacture of digital magnetic recording discs for computer disc drives requires the monitoring and control of the M-H hysteresis loop properties of the magnetic film deposited on the disc substrate. Several methods exist for measuring this M-H hysteresis loop, but they all have serious disadvantages. One method consists of cutting samples and measuring them with a vibrating sample magnetometer. This is a destructive test and requires a lot of time per sample. Another method uses the Kerr-rotation of polarized light. However, it samples only the mangetization of the surface and cannot determine the magnetic thickness of the film. A third method magnetizes the entire disc and samples a large region along a diameter. This method cannot distinguish between the top and bottom films of the disc, and cannot resolve circumferential variations of th M-H loop properties.

Abstract: The present invention concerns devices with probes for measuring magnetic potentials. Potential differences between two points of a material in a magnetic field are measured with a plurality of Hall probes arranged on a curved line which connects the points. The voltage of each Hall probe is connected with the summation point of an operational amplifier whose output voltage is proportional to the potential difference P=.intg.H.multidot.ds. A similar arrangement may also be used to measure the current in a conductor.

Abstract: A piece of the magnetic material to be tested is coupled to the device by primary and secondary windings. The material is then exposed to varying polarities of a controlled electrical current, such as a ramped current, through the primary winding causing the magnetic flux of the material to vary with respect to the controlled current; and creating varying voltage levels across the secondary winding. When this process has been completed the data is made available to a computer which now has data for the current levels transmitted through the primary winding and the corresponding voltage levels across the secondary winding. The computer can then utilize this data to provide a variety of magnetic property values of the magnetic material.

Abstract: Process and apparatus for measuring the hysteresis curves of magnetic materials when using a field coil and a potential coil of a size such that the ends of the latter coil project through the winding of the field coil. The process consists of integrating the output signal of the potential coil to obtain a first value, utilizing a voltage that is proportional to the field coil current to obtain a second value which is then added to the first value to obtain the field intensity H.In order to compensate for the presence of the legs of the potential coil, additional short windings of higher turn density are included in the field coil winding.

Abstract: A process for measuring the hysteresis curve of magnetic materials comprises the generation of a magnetic field of varying amplitude, placing the sample to be measured into that field with a measuring coil and a potential coil attached thereto, integrating the signals from those coils to provide simultaneous values of flux density B and internal field intensity H, recording and storing the B and H values and converting these values to digital units in a transient recorder in real time and then feeding these signals to an X-Y recorder, a printer or other display device at a slower rate of speed to provide a hysteresis curve, or a display of programmed values of magnetic characteristics of the sample being measured.