Magnetic field measurement system with amplitude-selective magnetic shield

Patent metadata

Field	Value
Publication number	US-11294008-B2
Application number	US-202016741593-A
Country	US
Kind code	B2
Filing date	Jan 13, 2020
Priority date	Jan 25, 2019
Publication date	Apr 5, 2022
Grant date	Apr 5, 2022

Abstract

A magnetic field measurement system for measurement of weak magnetic field signals or a wearable assembly includes at least one magnetometer and a shield disposed around the magnetometer. The shield includes a first portion configured for positioning between the at least one magnetometer and a source of the weak magnetic field signals. The first portion is made of an amplitude-selective magnetic shield (ASMS) that preferentially passes magnetic fields having a magnetic field amplitude below a threshold (for example, 500 nT or less) and shields magnetic fields having a larger magnetic field amplitude.

First claim

What is claimed as new and desired to be protected by Letters Patent of the United States is:

1. A wearable assembly, comprising:
at least one magnetometer; and
a shield disposed around the at least one magnetometer, wherein the shield comprises a first portion, wherein the first portion is configured to provide a shielding factor of at least 10 for a magnetic field having a magnetic field amplitude of 10 μT and to provide a shielding factor of no more than 2 for a magnetic field having a magnetic field amplitude of 1 nT.

2. The wearable assembly of claim 1 , wherein an entirety of the shield is configured to provide a shielding factor of at least 10 for a magnetic field having a magnetic field amplitude of 10 μT and to provide a shielding factor of no more than 2 for a magnetic field having a magnetic field amplitude of 1 nT.

3. The wearable assembly of claim 1 , wherein the shield comprises a second portion configured to provide a shielding factor of at least 10 for a magnetic field having a magnetic field amplitude of 1 nT.

4. The wearable assembly of claim 3 , wherein the second portion is made of mumetal.

5. The wearable assembly of claim 3 , wherein the first portion is a first layer and the second portion is a second layer disposed over or under the first layer.

6. The wearable assembly of claim 3 , wherein the second portion overlaps only part, which is less than an entirety, of the first portion.

7. The wearable assembly of claim 1 , wherein the first portion is made of an amorphous alloy comprising cobalt and iron and further comprising at least one of molybdenum, boron, silicon, or nickel.

8. A magnetic field measurement system for measurement of weak magnetic field signals, comprising:
the wearable assembly of claim 1 , wherein the first portion of the shield is configured for positioning between the at least one magnetometer and a source of the weak magnetic field signals.

9. A magnetic field measurement system for measurement of weak magnetic field signals, comprising:
at least one magnetometer; and
a shield disposed around the at least one magnetometer, wherein the shield comprises a first portion configured for positioning between the at least one magnetometer and a source of the weak magnetic field signals, wherein the first portion is configured to provide attenuation of a magnetic field having a magnetic field amplitude of 10 μT by at least 90% and to provide attenuation of a magnetic field having a magnetic field amplitude of 1 nT by no more than 50%.

10. The magnetic field measurement system of claim 9 , wherein an entirety of the shield is configured to provide attenuation of a magnetic field having a magnetic field amplitude of 10 μT by at least 90% and to provide attenuation of a magnetic field having a magnetic field amplitude of 1 nT by no more than 50%.

11. The magnetic field measurement system of claim 9 , wherein the shield comprises a second portion configured to provide attenuation of a magnetic field having a magnetic field amplitude of 1 nT by at least 90%.

12. The magnetic field measurement system of claim 11 , wherein the second portion is made of mumetal.

13. The magnetic field measurement system of claim 11 , wherein the first portion is a first layer and the second portion is a second layer disposed over or under the first layer.

14. The magnetic field measurement system of claim 11 , wherein the second portion overlaps only part, which is less than an entirety, of the first portion.

15. The magnetic field measurement system of claim 11 , wherein the first portion is made of an amorphous alloy comprising cobalt and iron and further comprising at least one of molybdenum, boron, silicon, or nickel.

16. A magnetic field measurement system for measurement of weak magnetic field signals, comprising:
at least one magnetometer; and
a shield disposed around the at least one magnetometer, wherein the shield comprises a first portion configured for positioning between the at least one magnetometer and a source of the weak magnetic field signals, wherein the first portion is made of an amorphous alloy comprising cobalt and iron which preferentially passes magnetic fields having a magnetic field amplitude of 500 nT or less.

17. The magnetic field measurement system of claim 16 , wherein the first portion of the shield is configured to provide attenuation of a magnetic field having a magnetic field amplitude of 10 μT by at least 90% and to provide attenuation of a magnetic field having a magnetic field amplitude of 1 nT by no more than 50%.

18. The magnetic field measurement system of claim 16 , wherein the first portion of the shield is configured to provide a shielding factor of at least 10 for a magnetic field having a magnetic field amplitude of 10 μT and to provide a shielding factor of no more than 2 for a magnetic field having a magnetic field amplitude of 1 nT.

19. The magnetic field measurement system of claim 18 , wherein the shield further comprises a second portion configured to provide a shielding factor of at least 10 for a magnetic field having a magnetic field amplitude of 1 nT.

20. The magnetic field measurement system of claim 19 , wherein the second portion overlaps only part, which is less than an entirety, of the first portion.

Assignees

• Hi Llc

Inventors

• Alford Jamu

Classifications

• G01R33/42 Primary

  Screening · CPC title

• G01R33/0076

  Protection, e.g. with housings against stray fields · CPC title

• G01R33/26

  using optical pumping · CPC title