MAGNETIC FIELD SOURCE DETECTING APPARATUS AND MAGNETIC FIELD SOURCE DETECTING METHOD

• US 20200132785A1
• Filed: 07/24/2019
• Published: 04/30/2020
• Est. Priority Date: 10/26/2018
• Status: Active Grant

• Current Assignee: Sumida Corporation
• Original Assignee: Sumida Corporation
• Inventors: YOSHII, Yoshiharu
• Granted Patent: US 11,067,646 B2
• Time in Patent Office: Days
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01N 24/10 by using electron paramagnetic resonance G01N24/12 takes precedence
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G01R 33/0094 Sensor arrays
• CPC Class Codes: G01R 33/02 Measuring direction or magnitude of magnetic fields or magnetic flux G01R33/20 takes precedence
• CPC Class Codes: G01R 33/032 using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
• CPC Class Codes: G01R 33/24 for measuring direction or magnitude of magnetic fields or magnetic flux
• CPC Class Codes: G01R 33/323 Detection of MR without the use of RF or microwaves, e.g. force-detected MR, thermally detected MR, MR detection via electrical conductivity, optically detected MR
• CPC Class Codes: G01R 33/383 using permanent magnets

Abstract

In a magnetic field source detecting apparatus, a magnetic sensor unit detects an intensity and a direction of a measurement target magnetic field on or over a surface of a test target object; and a position estimating unit estimates a position in a depth direction of a magnetic field source that exists at an unspecified position inside a test target object on the basis of the intensities and the directions of the measurement target magnetic field detected by the magnetic sensor at at least two 2-dimensional positions of the surface.

Claims

1. A magnetic field source detecting apparatus, comprising:

a magnetic sensor unit that detects an intensity and a direction of a measurement target magnetic field on or over a surface of a test target object; and

a position estimating unit that estimates a position in a depth direction of a magnetic field source that exists at an unspecified position inside a test target object on the basis of the intensities and the directions of the measurement target magnetic field detected by the magnetic sensor at at least two 2-dimensional positions of the surface.

2. The magnetic field source detecting apparatus according to claim 1, further comprising:

a measurement control unit; and

a reference magnetic field generating unit;

wherein the magnetic sensor unit comprises an optically detected magnetic resonance member, a coil that applies a magnetic field of a microwave to the optically detected magnetic resonance member, an irradiating device that irradiates the optically detected magnetic resonance member with light, and a light receiving device that detects light that the optically detected magnetic resonance member emits and outputs an electronic signal corresponding to the detected light;

the optically detected magnetic resonance member comprises plural specific color centers;

the specific color center has a Zeeman-splittable energy level and can take plural orientations of which energy level shift amounts due to Zeeman splitting are different from each other;

the reference magnetic field generating unit applies a reference magnetic field that causes Zeeman splitting of the energy level of the plural specific color centers;

the plural specific color centers have plural orientations different from each other, and the energy level of the plural specific color centers is Zeeman-splitted with different energy level shift amounts corresponding to the plural orientations by the reference magnetic field, respectively;

the measurement control unit changes a frequency of the microwave and determines a frequency characteristic of intensities of the light on the basis of the electronic signal at each of predetermined plural positions; and

the position estimating unit (a) determines a magnetic field component due to the measurement target magnetic field corresponding to each of the plural orientations on the basis of the frequency characteristic, (b) determines an intensity and a direction of the measurement target magnetic field on the basis of the magnetic field components corresponding to the plural orientations, and (c) estimates a position in a depth direction of the magnetic field source on the basis of the intensities and the directions of the measurement target magnetic field determined at the at least two positions.

3. The magnetic field source detecting apparatus according to claim 1, wherein the position estimating unit estimates a position in a depth direction of the magnetic field source on the basis of (a) a distribution characteristic of the measurement target magnetic field corresponding to a type of the magnetic field source and (b) the intensities and the directions of the measurement target magnetic field determined at the at least two positions.

4. The magnetic field source detecting apparatus according to claim 1, wherein the test target object is composed of a nonmagnetic material and

the magnetic field source is (a) a current that flows at an unspecified position inside the test target object or at one of conduction paths laid in multilayers or (b) a magnetic object that has entered at an unspecified position inside the test target object.

5. A magnetic field source detecting method comprising the steps of:

detecting intensities and directions of a measurement target magnetic field at at least two 2-dimensional positions of a surface of a test target object using a magnetic sensor unit that detects an intensity and a direction of the measurement target magnetic field on or over the surface of the test target object; and

estimating a position in a depth direction of a magnetic field source that exists at an unspecified position inside the test target object on the basis of the intensities and the directions of the measurement target magnetic field detected at the at least two 2-dimensional positions.