Pulsed scalar atomic magnetometer

Patent metadata

Field	Value
Publication number	US-10852371-B2
Application number	US-201615780322-A
Country	US
Kind code	B2
Filing date	Dec 1, 2016
Priority date	Dec 2, 2015
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

Disclosed is a method and apparatus relating generally to scalar atomic magnetometers. The disclosed methods and apparatus utilize a pressurized sample chamber and a high frequency pulsed pump laser to increase spin polarization and significantly suppress heading errors. These methods and apparatus may also include alternating polarization of the pump light between pulses.

First claim

What is claimed is:

1. A magnetometer, comprising:
a sample chamber;
a sample medium within the sample chamber, the sample medium comprising an alkali metal vapor and a quenching gas at a pressure greater than 100 torr that enables spin polarization of alkali metal atoms to be greater than or equal to a predetermined level; and
a pump laser having output directed towards the sample chamber, the laser having an intensity sufficiently high to polarize to a predetermined level in a period of time shorter than the Larmor precession period.

2. The magnetometer of claim 1 , wherein the predetermined level is 95% or greater.

3. The magnetometer of claim 1 , wherein the sample is optically thick.

4. The magnetometer of claim 3 , wherein the laser can propagate at least three optical lengths into the sample medium.

5. The magnetometer of claim 1 , further comprising a probe laser configured to produce a probe light directed towards the sample chamber.

6. The magnetometer of claim 5 , wherein at least a portion of the pump light and at least a portion of the probe light are collinear.

7. The magnetometer of claim 1 , wherein the pump laser is adapted to alternate the polarization of the pump laser between successive pulses.

8. The magnetometer of claim 1 , wherein the plurality of pulses are produced at a rate synchronous with repetitive magnetic field noise.

9. The magnetometer of claim 8 , wherein the rate is selected from the group consisting of 16.7 Hz, 25 Hz, 50 Hz, 60 Hz, and 400 Hz.

10. The magnetometer of claim 1 , wherein the pump laser is adapted to produce a plurality of pulses of at least one of o + or o − pump light.

11. A method for using a magnetometer to reduce heading error, comprising the steps of:
providing a magnetometer according to claim 1 ;
optically pumping alkali metal atoms using pulses of at least one of o + or o − pump light, the duration of each pulse being shorter than the Larmor period and the intensity of each pulse is sufficient to polarize atoms to a predetermined level of polarization; and
monitoring precession of spin of the alkali metal atoms with a probe laser and a detector for a period of time, the detector generating a detector signal, the detector signal having reduced heading error.

12. The method of claim 11 , wherein the predetermined level is 95% or greater.

13. The method of claim 11 , further comprising passing each pulse through a sample chamber containing the alkali metal vapor, wherein the sample chamber is configured such that the pump light propagates through the alkali metal vapor a sufficient number of optical lengths so as to allow at least some purification of circular polarization.

14. The method of claim 13 , wherein the pump light propagates at least 3 optical lengths through the alkali metal vapor.

15. The method of claim 11 , wherein the pulses of at least one of o + or o − pump light is produced by alternating the polarization of the pump laser between successive pulses.

16. The method of claim 11 , further comprising generating a spin-procession signal.

17. The method of claim 16 , wherein the period of time is approximately the spin-relaxation time.

18. The method of claim 16 , further comprising determining the frequency of the spin procession signal by non-linear fitting the signal to a decaying sine wave.

Assignees

• Univ Princeton
• Romalis Michael
• Dong Haifeng
• Baranga Andrei

Inventors

• Romalis Michael
• Dong Haifeng
• Baranga Andrei

Classifications

• G01R33/26 Primary

  using optical pumping · CPC title

• G01R33/032

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

• G01R33/02

  Measuring direction or magnitude of magnetic fields or magnetic flux (G01R33/20 takes precedence) · CPC title