# US 11,906,605 B1 · Apparatus, systems, and methods for measurement using magneto-optical Kerr effect

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- Number: US 11,906,605 B1
- Document ID: US11906605B1
- Status: Granted
- Kind: B1
- Application number: 17/516,618
- Filed: 2021-11-01
- Granted: 2024-02-20
- Earliest claimed: 2020-10-30
- Assignees: The United States of America as represented by the Secretary of the Navy
- Applicants: The Government of the United States of America, as represented by the Secretary of the Navy
- Inventors: Nicholas J. Jones; Emily L. Guzas; Matthew T. Roberts; Wayne C. Tucker
- Web page: https://patentgrep.com/patent/US11906605B1

## CPC

- G01R 33/1223: {Measuring permeability, i.e. permeameters (G01R33/14 takes precedence)}
- G01R 33/0325: {using the Kerr effect}
- G01R 33/07: Hall effect devices
- G01R 33/1215: {Measuring magnetisation; Particular magnetometers therefor (G01R33/14 takes precedence; electrodynamic magnetometers G01R33/028)}
- G08B 21/182: {Level alarms, e.g. alarms responsive to variables exceeding a threshold}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS

## Abstract

The magneto-optical Kerr effect (MOKE) is used to capture variations in magnetic permeability and magnetization to determine the presence of sensitization. MOKE-magnetometry-based systems and apparatus may be used to provide in-field magnetic measurements, and may be particularly useful in methods for assessing changes in composition, crystal structure, and grain size in magnetic materials.

## Claims

### Claim 1

Apparatus for measuring magnetic permeability and magnetization in a magnetic alloy, comprising:
a magneto-optical Kerr effect (MOKE) microscope provided within a metallic housing having an aperture therein;
attachment means for removably attaching the metallic housing to a surface of the magnetic alloy; and
a magnetic field-producing apparatus provided with arms for conducting the magnetic field to a surface of the magnetic alloy.

### Claim 2 (depends on 1)

The apparatus of claim 1, where the arms are formed from a high permeability material selected from the group consisting of iron and electrical steel.

### Claim 3 (depends on 1)

The apparatus of claim 1, where the magnetic field-producing apparatus uses a permanent magnet to produce the magnetic field.

### Claim 4 (depends on 1)

The apparatus of claim 1, where the magnetic field-producing apparatus uses a solenoid coil to produce the magnetic field.

### Claim 5 (depends on 1)

The apparatus of claim 1, further comprising a Hall effect sensor.

### Claim 6 (depends on 1)

The apparatus of claim 1, further comprising adjustable mirrors for directing a laser beam emitted by the MOKE microscope.

### Claim 7 (depends on 1)

The apparatus of claim 1, further comprising positioning apparatus for moving the MOKE microscope within the metallic housing.