Atomic far-off resonance trap (FORT) accelerometer system

Patent metadata

Field	Value
Publication number	US-9234912-B2
Application number	US-201313907250-A
Country	US
Kind code	B2
Filing date	May 31, 2013
Priority date	Jun 6, 2012
Publication date	Jan 12, 2016
Grant date	Jan 12, 2016

Abstract

One embodiment includes an accelerometer system. The accelerometer system can include a Far-Off Resonance Trap (FORT) control system configured to generate an optical trapping beam. The system can also include a FORT accelerometer detection system including a FORT that is configured to trap a cluster of atoms based on the optical trapping beam. The FORT accelerometer detection system can also include an interrogation system configured to determine motion of the cluster of atoms along at least one axis resulting from an external acceleration in the at least one axis based on a relative phase shift of an optical probe beam through the cluster of atoms. The system can further include an acceleration processor configured to calculate the external acceleration in the at least one axis based on the relative phase shift of the optical probe beam.

First claim

What is claimed is:

1. An accelerometer system comprising:
a Far-Off Resonance Trap (FORT) control system configured to generate an optical trapping beam;
a FORT accelerometer detection system comprising a FORT that is configured to trap a cluster of atoms based on the optical trapping beam, and also comprising an interrogation system configured to determine motion of the cluster of atoms along at least one axis resulting from an external acceleration in the at least one axis based on a relative phase shift of an optical probe beam through the cluster of atoms; and
an acceleration processor configured to calculate the external acceleration in the at least one axis based on the relative phase shift of the optical probe beam.

2. The system of claim 1 , wherein the FORT accelerometer detection system comprises a plurality of resonator cavities, such that the acceleration processor is configured to calculate the external acceleration in a plurality of orthogonal axes.

3. The system of claim 2 , wherein the plurality of resonator cavities are each arranged orthogonal with respect to each other and are each configured to trap a respective one of a plurality of clusters of atoms, such that the interrogation system is configured to determine motion of each of the plurality of clusters of atoms in separate respective orthogonal axes based on a relative phase shift of a respective plurality of optical probe beams through the respective pluralities of clusters of atoms.

4. The system of claim 2 , wherein the plurality of resonator cavities are arranged as a three-axis resonator cavity configured to trap the cluster of atoms based on three respective orthogonal trapping beams, such that the interrogation system is configured to determine motion of the cluster of atoms resulting from the external acceleration in three orthogonal axes based on a relative phase shift of three orthogonal optical probe beams through the cluster of atoms.

5. The system of claim 4 , wherein the three orthogonal trapping beams are provided as having approximately equal energy to trap the cluster of atoms with approximately equal force in each of the three-orthogonal axes.

6. The system of claim 1 , wherein the FORT control system comprises a potential well-depth controller configured to control an intensity of the optical trapping beam to adjust a magnitude of a trapping force associated with the FORT to adjust a sensitivity of the FORT accelerometer detection system.

7. The system of claim 1 , wherein the FORT accelerometer detection system comprises an optical phase detection system configured to calculate the relative phase shift of the optical probe beam through the cluster of atoms based on motion of the cluster of atoms along the at least one axis from an approximate center point of the FORT.

8. The system of claim 1 , wherein the interrogation system comprises an optical cavity configured to resonate the optical probe beam.

9. The system of claim 1 , wherein the FORT comprises a pair of oppositely-disposed concave minors configured to resonate the optical trapping beam in a manner to substantially converge the optical trapping beam at an approximate center of the FORT to trap the cluster of atoms at the approximate center of the FORT.

10. The system of claim 8 , wherein the cluster of atoms comprises a cluster of alkali metal atoms, and wherein the optical trapping beam is configured as one of a red and blue-detuned laser beam having a sufficiently narrow beam-waist and sufficient power for trapping the cluster of alkali metal atoms in the FORT.

11. A method for measuring an external acceleration in a Far-Off Resonance Trap (FORT) accelerometer system, the method comprising:
generating an optical trapping beam;
providing the optical trapping beam in a FORT to resonate the optical trapping beam in the FORT to trap a cluster of atoms at an approximate center of the FORT;
providing an optical probe beam through the approximate center of the FORT orthogonally with respect to a sensitive axis of the FORT accelerometer system;
monitoring a phase of the optical probe beam passing through the cluster of atoms; and
calculating an external acceleration along the sensitive axis of the FORT accelerometer system based on a relative phase shift of an optical probe beam through the cluster of atoms resulting from motion of the cluster of atoms along the sensitive axis in response to the external acceleration.

12. The method of claim 11 , wherein providing the optical trapping beam in the FORT comprises providing a plurality of optical trapping beams in a respective plurality of orthogonal optical cavities, wherein providing the optical probe beam through the approximate center of the FORT comprises providing a plurality of optical probe beams through an approximate center of the respective plurality of orthogonal optical cavities, and wherein calculating the external acceleration comprises calculating the external acceleration along each orthogonal axis of the FORT accelerometer system based on a relative phase shift of the plurality of optical probe beams through the respective cluster of atoms.

13. The method of claim 12 , wherein providing the plurality of optical trapping beams in a respective plurality of orthogonal optical cavities comprises providing the plurality of optical trapping beams in orthogonal directions through a single cluster of atoms.

14. The method of claim 11 , further comprising controlling an intensity of the optical trapping beam to adjust a magnitude of a trapping force associated with the FORT to adjust a sensitivity of the FORT accelerometer system.

15. The method of claim 11 , wherein providing the optical trapping beam in the FORT comprises providing the optical trapping beam in the FORT comprising a pair of oppositely-disposed concave mirrors configured to resonate the optical trapping beam in a manner to substantially converge the optical trapping beam at the approximate center of the FORT to trap the cluster of atoms at the approximate center of the FORT.

16. The method of claim 11 , wherein providing the optical probe beam through the approximate center of the optical cavity comprises providing the optical probe beam in an optical cavity through the approximate center of the FORT orthogonally with respect to the sensitive axis of the FORT accelerometer system.

17. An accelerometer system comprising:
a Far-Off Resonance Trap (FORT) control system configured to generate at least one optical trapping beam;
a FORT accelerometer detection system comprising:
a FORT configured to trap at least one cluster of alkali atoms based on the at least one optical trapping beam; and
an interrogation system comprising a plurality of orthogonal FORTs configured to resonate the at least one optical trapping beam in a respective plurality of orthogonal axes and being configured to determine motion of the at least one cluster of alkali atoms in each of the plurality of orthogonal axes resulting from an external acceleration based on a relative phase shift of a respective plurality of optical probe beams resonating through the at least one cluster of alkali atoms; and

an acceleration processor configured to calculate the external acceleration in the at least one axis based on the relative phase shift of the optical probe beam.

18. The system of claim 17 , wherein each of the at least one orthogonal trapping beam is provided as having approximately equal energy to trap the respective at least one cluster of alkali atoms with approximately equal force in each of the plurality of orthogonal a

Assignees

• Walker Thad G
• Larsen Michael S
• Northrop Grumman Systems Corp

Inventors

• Walker Thad G
• Larsen Michael S

Classifications

• G01P15/08

  with conversion into electric or magnetic values · CPC title

• G01P15/093

  by photoelectric pick-up · CPC title

• G01P15/006 Primary

  by making use of fluid seismic masses · CPC title

• G01P15/18

  in two or more dimensions · CPC title