Atomic magnetometer system

Patent metadata

Field	Value
Publication number	US-2022018913-A1
Application number	US-202016928609-A
Country	US
Kind code	A1
Filing date	Jul 14, 2020
Priority date	Jul 14, 2020
Publication date	Jan 20, 2022
Grant date	—

Abstract

One example includes a magnetometer that includes a sensor cell comprising alkali metal vapor and a magnetic field generator system that generates predetermined AC magnetic fields through the sensor cell. The magnetometer also includes a laser system to provide optical pump and probe beams through the sensor cell in a pulsed manner to facilitate precession of the alkali metal vapor and to provide a detection beam corresponding to the optical probe beam exiting the sensor cell. The detection beam exhibits an optical property corresponding to a modified precession of the alkali metal vapor based on the predetermined AC magnetic fields and an external magnetic field. The magnetometer also includes a detection system to monitor the detection beam to detect the modified precession of the alkali metal vapor to calculate scalar and vector components of the external magnetic field based on the plurality of predetermined AC magnetic fields.

First claim

What is claimed is:

1 . A magnetometer comprising:
a sensor cell comprising alkali metal vapor; a magnetic field generator system configured to generate a plurality of predetermined AC magnetic fields through the sensor cell; a laser system configured to provide an optical pump beam and an optical probe beam through the sensor cell in a pulsed manner to facilitate precession of the alkali metal vapor and to provide a detection beam corresponding to the optical probe beam exiting the sensor cell, the detection beam exhibiting an optical property corresponding to a modified precession of the alkali metal vapor based on the plurality of predetermined AC magnetic fields and an external magnetic field; and a detection system configured to monitor the detection beam to detect the modified precession of the alkali metal vapor to calculate a scalar component and to calculate a vector component of the external magnetic field based on the plurality of predetermined AC magnetic fields.

2 . The magnetometer of claim 1 , wherein the laser system comprises an optical coupler configured to axially combine the optical pump beam and the optical probe beam to generate a combined beam that is directed through the sensor cell.

3 . The magnetometer of claim 1 , wherein the detection system is configured to measure a total magnetic field that comprises the external magnetic field and the plurality of predetermined AC magnetic fields, and is configured to demodulate the total magnetic field by each of the plurality of predetermined AC magnetic fields to calculate the scalar and vector components of the external magnetic field.

4 . The magnetometer of claim 3 , wherein each of the plurality of AC magnetic fields is provided at a separate respective frequency, such that the detection system is configured to demodulate the total magnetic field by each separate respective frequency of the respective plurality of predetermined AC magnetic fields to calculate the scalar and vector components of the external magnetic field.

5 . The magnetometer of claim 3 , wherein the plurality of predetermined AC magnetic fields are provided at predetermined relative angles with respect to each other in three dimensional space, such that the detection system is configured to demodulate the total magnetic field by each of the respective plurality of predetermined AC magnetic fields to determine the vector components of the external magnetic field relative to the predetermined relative angles of the plurality of predetermined AC magnetic fields.

6 . The magnetometer of claim 5 , wherein the plurality of predetermined AC magnetic fields comprises three AC magnetic fields that are each approximately orthogonal with respect to each other.

7 . The magnetometer of claim 3 , wherein the detection system is configured to square the total magnetic field and to demodulate the squared total magnetic field by first and second harmonics associated with the plurality of predetermined AC magnetic fields to calculate the scalar and vector components of the external magnetic field.

8 . The magnetometer of claim 1 , wherein the optical probe beam and the optical pump beam are provided in a pulsed manner at a frequency corresponding to a precession frequency of the alkali metal vapor.

9 . A magnetometer system comprising a plurality of magnetometers of claim 1 that are arranged in an array and each configured to calculate the scalar and vector components of the external magnetic field, the magnetometer system further comprising a magnetic field tensor processor configured to calculate a magnetic field gradient associated with the external magnetic field.

10 . The magnetometer system of claim 9 , wherein at least a portion of the plurality of magnetometers are arranged in a planar array.

11 . The magnetometer system of claim 10 , wherein at least one of the plurality of magnetometers is offset from the planar array to provide a redundant calculation of the scalar and vector components of the external magnetic field.

12 . A method for measuring a scalar component and a vector component of an external magnetic field via a magnetometer system, the method comprising:
providing a plurality of predetermined AC magnetic fields through a sensor cell associated with a magnetometer, the sensor cell comprising an alkali metal vapor; providing an optical probe beam and an optical pump beam through the sensor cell in a pulsed manner; determining a total magnetic field comprising the external magnetic field and each of the plurality of predetermined AC magnetic fields in response to receiving a detection beam corresponding to the optical probe beam exiting the sensor cell; and demodulating the total magnetic field based on the plurality of predetermined AC magnetic fields to calculate the scalar component and the vector component of the external magnetic field.

13 . The method of claim 12 , wherein providing the optical pump beam and providing the optical probe beam comprises axially combining the optical probe beam and the optical pump beam to provide a combined beam through the sensor cell in a pulsed manner that is based on a precession frequency of the alkali metal vapor.

14 . The method of claim 12 , wherein providing the plurality of predetermined AC magnetic fields comprises providing the plurality of predetermined AC magnetic fields at separate respective frequencies and at separate predetermined relative angles with respect to each other in three dimensional space, such that the detection system is configured to demodulate the total magnetic field by each separate respective frequency of the respective plurality of predetermined AC magnetic fields and relative to each separate predetermined relative angle to calculate the scalar and vector components of the external magnetic field.

15 . The method of claim 12 , further comprising squaring the total magnetic field, wherein demodulating the total magnetic field comprises demodulating the squared total magnetic field by first and second harmonics associated with the plurality of predetermined AC magnetic fields to calculate the scalar and vector components of the external magnetic field.

16 . The method of claim 12 , further comprising:
determining the scalar and vector components of the external magnetic field via each of a plurality of magnetometers arranged in a planar array; and determining a magnetic field gradient based on the determination of the scalar and vector components of the external magnetic field via each of a plurality of magnetometers.

17 . A magnetometer system comprising:
a plurality of magnetometers, each of the magnetometers comprising:
a sensor cell comprising alkali metal vapor;
a magnetic field generator system configured to generate a plurality of predetermined AC magnetic fields through the sensor cell;
a laser system configured to provide an optical pump beam and an optical probe beam through the sensor cell in a pulsed manner to facilitate precession of the alkali metal vapor and to provide a detection beam corresponding to the optical probe beam exiting the sensor cell, the detection beam exhibiting an optical property corresponding to a modified precession of the alkali metal vapor based on the plurality of predetermined AC magnetic fields and an external magnetic field; and
a detection system configured to monitor the detection beam to detect the modified precession of the alkali metal vapor to calculate a scalar component and to calculate a vector component of the external magnetic field based on the plurality of predetermined AC ma

Assignees

• Walker Thad G
• Bulatowicz Michael D
• Northrop Grumman Systems Corp

Inventors

• Walker Thad G
• Bulatowicz Michael D

Classifications

• G01R33/032

  using magneto-optic devices, e.g. Faraday {or Cotton-Mouton effect} · CPC title

• G01R33/0017

  Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields · CPC title

• G01R33/26 Primary

  using optical pumping · CPC title

• G01R33/0094

  Sensor arrays · CPC title