Magnetic imaging system for display of local variations of magnetic properties in magnetic material

Claim 2

A multiparameter magnetic imaging system for deriving and displaying a multidimensional color representation of intrinsic magnetic properties of a material derived from a plurality of hysteresis measurements, the system comprising in combination: means including an inspection probe for subjecting localized areas of a specimen of the material to a magnetic field and measuring the localized response of the specimen, control means associated with the inspection probe for controllably varying the strength of the magnetic field to produce and store localized hysteresis measurements; means for scanning said probe over the surface of the specimen for taking a sequence of localized hysteresis measurements at each of a plurality of locations across the specimen surface; means for correlating said localized hysteresis measurements to the locations on said specimen surface at which the measurements were taken; means for deriving values for at least one intrinsic magnetic property for the respective locations of the specimen from said localized hysteresis measurements; and means for displaying a false color image of the surface of the specimen in which the color displayed for the surface at each respective location is related to the value of the derived intrinsic magnetic property at the respective locations, to produce a color map of the specimen surface displaying the variation of the derived intrinsic magnetic property across said specimen surface.

Claim 3

The system of claim 1 wherein: the means for deriving derives values for a plurality of intrinsic magnetic properties for each respective location from said localized hysteresis measurements; and the means for displaying assigns respective colors to the respective derived intrinsic magnetic properties to cause the false color image to distinguish therebetween.

Claim 4

The system of claim 1, wherein said control means for controlling the magnetic field comprises a programmable power supply.

Claim 5

The system of claim 1, further comprising data acquisition means for collecting and storing the localized hysteresis measurements collected by said inspection probe.

Claim 6

The system of claim 1, wherein said means for correlating the localized hysteresis measurements to locations across said specimen surface comprise a computer.

Claim 7

The system of claim 1, further comprising data storage means for storing magnetic and positional data.

Claim 8

The system of claim 1, wherein said magnetic property displayed on said false color image is selected from the group which includes coercivity, remanence, hysteresis loss, initial permeability, maximum differential permeability and differential permeability at remanence.

Claim 9

The system of claim 1, further comprising positioning means for positioning the probe across said specimen surface.

Claim 10

A multiparameter magnetic imaging system for deriving and displaying a multi-dimensional color representation of intrinsic magnetic properties occurring across the surface of a specimen derived from a plurality of hysteresis measurements, the system comprising in combination: an inspection probe for generating and measuring a magnetic field and measuring magnetic flux in localized areas of the specimen; a control system for controlling the power supplied to said inspection probe at a plurality of levels to generate a controllably variable magnetic field; acquisition means for collecting the magnetic field and flux data measured by said inspection probe to produce localized hysteresis measurements; means for scanning the inspection probe across the surface of the specimen to cause the acquisition means to collect the localized hysteresis measurements for a plurality of locations across the surface as the inspection probe is scanned over said surface; means for deriving values for at least one intrinsic magnetic properties for the respective locations of the specimen from the localized hysteresis measurements; means for correlating the derived intrinsic magnetic property values of the specimen to the locations across the specimen surface at which the hysteresis measurements were made; means for storing data representative of said derived intrinsic property values in indexed relation to said locations across the specimen surface; and means for displaying a false color image of the specimen surface in which the color displayed for the surface at the respective locations is related to the values of the derived intrinsic magnetic property.

Claim 11

A multiparameter magnetic imaging system for deriving and displaying a multi-dimensional color representation of intrinsic magnetic properties occurring across the surface of a specimen derived from a plurality of hysteresis measurements, the system comprising in combination: an inspection probe for generating and measuring a magnetic field and measuring magnetic flux in localized areas of the specimen; a control system for controlling the power supplied to said inspection probe at a plurality of levels to generate a controllably variable magnetic field; acquisition means for collecting the magnetic field and flux data measured by said inspection probe to produce localized hysteresis measurements; means for scanning the inspection probe across the surface of the specimen to cause the acquisition means to collect the localized hysteresis measurements for a plurality of locations across the surface as the inspection probe is scanned over said surface; means for deriving values for at least one intrinsic magnetic properties for the respective locations of the specimen from the localized hysteresis measurements; means for correlating the derived intrinsic magnetic property values of the specimen to the locations across the specimen surface at which the hysteresis measurements were made; means for storing data representative of said derived intrinsic property values in indexed relation to said locations across the specimen surface; and means for displaying a false color image of the specimen surface in which the color displayed for the surface at the respective locations is related to the values of the derived intrinsic magnetic property.

Claim 12

The system of claim 9, wherein said magnetic property displayed on said false color image is selected from a group which includes coercivity, remanence, hysteresis loss, initial permeability, maximum differential permeability and differential permeability at remanence.

Claim 13

The system of claim 9, further comprising scanning means to scan said inspection probe across said specimen surface.

Claim 14

The system of claim 9 in which: the means deriving derives a plurality of intrinsic magnetic properties for the respective locations of the specimen from the hysteresis measurements; and the means for displaying produces false color images for the respective derived intrinsic magnetic properties which distinguish between the derived intrinsic magnetic properties.

Claim 17

The method of claim 13, wherein the hysteresis measurements across the surface of the specimen are measurements of field strength and magnetic flux in the specimen.

Claim 18

The method of claim 14, wherein the determined magnetic property is selected from a group which includes coercivity, remanence, hysteresis loss, initial permeability, maximum differential permeability and differential permeability at remanence.

Claim 19

The method of claim 13 wherein: the determining step determines a plurality of intrinsic magnetic properties across the surface of the specimen from the hysteresis measurements; and the displaying step assigns different colors to the false color image of the specimen for the respective determined intrinsic magnetic properties to distinguish therebetween.

Claim 22

The method of claim 17, wherein said determined magnetic property is selected from a group which includes coercivity, remanence, hysteresis loss, initial permeability, maximum differential permeability and differential permeability at remanence.

Claim 23

The method of claim 17 in which: the step of determining determines a plurality of magnetic properties at each said location; and the step of displaying assigns different colors to the false color image of the specimen by the respective derived intrinsic magnetic properties to distinguish therebetween.