Wavelength-modulated coherence pumping and hyperfine repumping for an atomic magnetometer

Patent metadata

Field	Value
Publication number	US-9869731-B1
Application number	US-201414230354-A
Country	US
Kind code	B1
Filing date	Mar 31, 2014
Priority date	Mar 31, 2014
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

An FM-NMOR magnetometer and concomitant magnetometry method comprising providing a linearly-polarized pump beam generator, employing a center wavelength approximately equal to a center wavelength of hyperfine peaks, and employing a modulation amplitude in the range HFS-3×LW to HFS.

First claim

What is claimed is:

1. An FM-NMOR magnetometer comprising a linearly-polarized pump beam generator generating a center wavelength approximately equal to a center wavelength of hyperfine peaks and generating a modulation amplitude in the range HFS-3×LW (Hyperfine Splitting interval minus three times Line Width) to HFS (Hyperfine Splitting interval) with respect to atoms in an atomic vapor cell through which an output of said beam generator passes, wherein a modulation frequency of said beam generator is determined from a magnetic field measured by said magnetometer.

2. The magnetometer of claim 1 whereby wherein the center laser wavelength is stabilized by feedback from light passing through the atomic vapor cell.

3. The magnetometer of claim 2 additionally comprising a lock-in amplifier adjusted to an odd multiple of the modulation frequency.

4. The magnetometer of claim 2 wherein stabilization is provided by a separate atomic vapor cell.

5. The magnetometer of claim 4 wherein a line width of the separate atomic vapor cell has been broadened by a buffer gas.

6. The magnetometer of claim 1 wherein the modulation amplitude is in the range HFS-2×LW (Hyperfine Splitting interval minus two times Line Width) to HFS-LW (Hyperfine Splitting interval minus Line Width).

7. The magnetometer of claim 1 wherein said generator generates a modulation waveform that is a simple or modified square wave.

8. The magnetometer of claim 1 wherein said generator generates a modulation waveform that is a sine wave.

9. An FM-NMOR magnetometry method comprising providing a linearly-polarized pump beam generator, generating a center wavelength approximately equal to a center wavelength of hyperfine peaks, and generating a modulation amplitude in the range HFS-3×LW (Hyperfine Splitting interval minus three times Line Width) to HFS (Hyperfine Splitting interval) with respect to atoms in an atomic vapor cell through which an output of the beam generator passes, wherein a modulation frequency of the beam generator is determined from a measured magnetic field.

10. The method of claim 9 additionally comprising stabilizing the center laser wavelength by feedback from light passing through the atomic vapor cell.

11. The method of claim 10 additionally comprising adjusting a lock-in amplifier to an odd multiple of the modulation frequency.

12. The method of claim 10 additionally comprising providing stabilization via another atomic vapor cell.

13. The method of claim 12 additionally comprising broadening a line width of the other atomic vapor cell by a buffer gas.

14. The method of claim 9 wherein the modulation amplitude is in the range HFS-2×LW (Hyperfine Splitting interval minus two times Line Width) to HFS-LW (Hyperfine Splitting interval minus Line Width).

15. The method of claim 9 additionally comprising using a modulation waveform that is a simple or modified square wave.

16. The method of claim 9 additionally comprising using a modulation waveform that is a sine wave.

Assignees

• Southwest Sciences Incorporated
• Univ California

Inventors

• Hovde David Christian
• Budker Dmitry
• Patton Brian

Classifications

• G01R33/26 Primary

  using optical pumping · CPC title

• G01R33/032

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