Devices, systems, and methods with optical pumping magnetometers for three-axis magnetic field sensing

Patent metadata

Field	Value
Publication number	US-11604237-B2
Application number	US-202217569287-A
Country	US
Kind code	B2
Filing date	Jan 5, 2022
Priority date	Jan 8, 2021
Publication date	Mar 14, 2023
Grant date	Mar 14, 2023

Abstract

A magnetic field measurement system includes a magnetometer having at least one vapor cell, at least one light source to direct at least two light beams through the vapor cell(s), and at least one detector; at least one magnetic field generator to modify an external magnetic field experienced by the vapor cell(s); and at least one processor configured for: applying a first modulation pattern, bmod(t), to the magnetic field generator(s) to modulate a magnetic field at the vapor cell(s), where bmod(t)=[cx cos(ωt)+sx sin(ωt), cy cos(ωt)+sy sin(ωt), cz cos(ωt)+sz sin(ωt)], where cx, sx, cy, sy, cz, and sz are amplitudes and ω is a frequency; directing the light source(s) to direct the light beams through the vapor cell(s); receiving signals from the detector(s); and determining three orthogonal components of the external magnetic field using the received signals. Multi-frequency modulation patterns can alternatively be used.

First claim

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

1. A magnetic field measurement system, comprising:
a magnetometer comprising at least one vapor cell, at least one light source configured to direct at least two light beams through the at least one vapor cell, and at least one detector configured to receive the at least two light beams directed through the at least one vapor cell, wherein at least two of the at least two light beams are not parallel and do not overlap;
at least one magnetic field generator disposed adjacent the at least one vapor cell and configured to modify an external magnetic field experienced by the at least one vapor cell; and
at least one processor coupled to the magnetometer and the at least one magnetic field generator, wherein the at least one processor is configured for:
applying a first modulation pattern, b mod (t), to the at least one magnetic field generator to modulate a magnetic field at the at least one vapor cell of the magnetometer using the first modulation pattern, wherein b mod (t)=[c x cos(ωt)+s x sin(ωt), c y cos(ωt)+s y sin(ωt), c z cos(ωt)+s z sin(ωt)], wherein c x , s x , c y , s y , c z , and s z are amplitudes and ω is a frequency of the first modulation pattern, wherein at least one of each pair (c i , s i ) is non-zero, where i is x, y, or z;
directing the at least one light source to direct the at least two light beams through the at least one vapor cell;
receiving signals from the at least one detector in response to receiving the at least two light beams during the application of the first modulation pattern; and
determining three orthogonal components of the external magnetic field at the magnetometer using the received signals.

2. The magnetic field measurement system of claim 1 , wherein c x , s y , and c z equal zero and s x , c y , and s z equal B m , wherein B m is an amplitude of the first modulation pattern.

3. The magnetic field measurement system of claim 1 , wherein c x , s y , and c z equal B m and s x , c y , and s z equal zero, wherein B m is an amplitude of the first modulation pattern.

4. The magnetic field measurement system of claim 1 , wherein the at least one vapor cell is only one vapor cell.

5. The magnetic field measurement system of claim 1 , wherein the at least one vapor cell is a plurality of vapor cells.

6. The magnetic field measurement system of claim 1 , wherein the at least two light beams comprise at least three light beams and at least two of the at least three light beams are parallel to each other.

7. The magnetic field measurement system of claim 1 , wherein the at least two of the at least two light beams that are not parallel are orthogonal to each other.

8. The magnetic field measurement system of claim 1 , wherein determining the three orthogonal components of the external magnetic field comprises determining a matrix M, wherein the external magnetic field is equal to M#S, wherein M# is a pseudo-inverse of the matrix M and S is the received signals.

9. The magnetic field measurement system of claim 8 , wherein S=[S 1 , S 2 ], wherein
S 1 =A 1c cos(ω t )+ A 1s sin(ω t )

and
S 2 =A 2c cos(ω t )+ A 2s sin(ω t ).

10. The magnetic field measurement system of claim 9 , wherein

M
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Assignees

• Hi Llc

Inventors

• Ledbetter Micah
• Shapiro Benjamin
• Pratt Ethan
• Jimenez-Martinez Ricardo
• Dellis Argyrios
• Wright-Freeman Kayla
• Iwata Geoffrey
• Romalis Michael

Classifications

• G01R33/26 Primary

  using optical pumping · CPC title

• A61B5/245

  specially adapted for magnetoencephalographic [MEG] signals · CPC title

• A61B5/7203

  for noise prevention, reduction or removal · CPC title

• A61B5/7235

  Details of waveform analysis (detecting specific parameters of the electrocardiograph cycle A61B5/349) · CPC title