Apparatus and method for resonance magneto-optical defect center material pulsed mode referencing

Patent metadata

Field	Value
Publication number	US-10228429-B2
Application number	US-201715468289-A
Country	US
Kind code	B2
Filing date	Mar 24, 2017
Priority date	Mar 24, 2017
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

The present disclosure relates to apparatuses and methods for stimulating a magneto-optical defect material with defect centers in a magnetic detection system using a stimulation process to significantly increase magnetic sensitivity of the detection system. The system utilizes a modified Ramsey pulse sequence pair or a shifted magnetometry adapted cancellation (SMAC) pair to detect and measure the magnetic field acting on the system resulting in mitigation of low-frequency noise sources to provide improved sensor sensitivity. For a SMAC pair measurement, two different values of tau are used as well as two different values of the microwave pulse width.

First claim

What is claimed is:

1. A system for magnetic detection, comprising:
a magneto-optical defect center material comprising a plurality of defect centers and lattice oriented subsets;
a radio frequency (RF) excitation source configured to provide RF excitation to the magneto-optical defect center material;
an optical excitation source configured to provide optical excitation to the magneto-optical defect center material;
an optical detector configured to receive an optical signal emitted by the magneto-optical defect center material;
a bias magnet configured to separate RF resonance responses of the lattice oriented subsets of the magneto-optical defect center material;
and
a controller configured to:
control the optical excitation source and the RF excitation source to apply a first pulse sequence to the magneto-optical defect center material, the first pulse sequence comprising a first optical excitation pulse, a first pair of RF excitation pulses separated by a first time period, and a second optical excitation pulse to the magneto-optical defect center material;
control the optical excitation source and the RF excitation source to apply a second pulse sequence to the magneto-optical defect center material, the second pulse sequence comprising a third optical excitation pulse, a second pair of RF excitation pulses separated by a second time period, and a fourth optical excitation pulse to the magneto-optical defect center material, wherein a pulse width of the first pair of RF excitation pulses is different than a pulse width of the second pair of RF excitation pulses, and wherein first time period is different than the second time period;
receive a first light detection signal from the optical detector based on an optical signal emitted by the magneto-optical defect center material due to the first pulse sequence;
receive a second light detection signal from the optical detector based on an optical signal emitted by the magneto-optical defect center material due to the second pulse sequence; and
compute a combined measurement based on a difference between a measured value of the first light detection signal and a measured value of the second light detection signal wherein the slope of the combined measurement is greater than the slope of the measured value of the first and second light detection signals.

2. The system of claim 1 , wherein an RF excitation frequency used for the first pair of RF excitation pulses and the second pair of RF excitation pulses is associated with an axis of a defect center of the magneto-optical defect center material.

3. The system of claim 1 , wherein the controller is further configured to compute a change in an external magnetic field acting on the magneto-optical defect center material based on the combined measurement.

4. The system of claim 1 , wherein the second pair of RF excitation pulses of the first pulse sequence are applied at a frequency detuned from a resonance frequency of the magneto-optical defect center material.

5. The system of claim 1 , wherein the pulse width of the second pair of RF excitation pulses is associated with a fluorescence null point of the magneto-optical defect center material.

6. The system of claim 1 , wherein the second time period is associated with a fluorescence null point of the magneto-optical defect center material.

7. The system of claim 1 , wherein the pulse width of the second pair of RF excitation pulses and the second time period is associated with a fluorescence null point of the magneto-optical defect center material.

8. The system of claim 7 , wherein the pulse width of the first pair of RF excitation pulses and the first time period is associated with a fluorescence low point of the magneto-optical defect center material.

9. The system of claim 1 , wherein the RF excitation source is a microwave antenna.

10. The system of claim 1 , wherein the controller is configured to apply the first pair of RF excitation pulses followed by the second pair of RF excitation pulses.

11. The system of claim 1 , wherein the bias magnet is one of a permanent magnet, a magnet field generator, or a Halbach set of permanent magnets.

12. A method for magnetic detection using a magneto-optical defect center material comprising a plurality of defect centers, the method comprising:
applying a first pulse sequence to the magneto-optical defect center material, the first pulse sequence comprising a first optical excitation pulse, using an optical excitation source, a first pair of RF excitation pulses separated by a first time period using a radio frequency (RF) excitation source, and a second optical excitation pulse to the magneto-optical defect center material using the optical excitation source;
applying a second pulse sequence to the magneto-optical defect center material, the second pulse sequence comprising a third optical excitation pulse, using the optical excitation source, a second pair of RF excitation pulses separated by a second time period using the RF excitation source, and a fourth optical excitation pulse to the magneto-optical defect center material, using the optical excitation source, wherein a pulse width of the first pair of RF excitation pulses is different than a pulse width of the second pair of RF excitation pulses, and wherein first time period is different than the second time period;
receiving a first light detection signal, using an optical detector, based on an optical signal emitted by the magneto-optical defect center material due to the first pulse sequence;
receive a second light detection signal, using the optical detector, based on an optical signal emitted by the magneto-optical defect center material due to the second pulse sequence; and
computing a combined measurement based on a difference between a measured value of the first light detection signal and a measured value of the second light detection signal.

13. The method of claim 12 , wherein an RF excitation frequency used for the first pair of RF excitation pulses and the second pair of RF excitation pulses is associated with an axis of a defect center of the magneto-optical defect center material.

14. The method of claim 12 , further comprising computing a change in an external magnetic field acting on the magneto-optical defect center material based on the combined measurement.

15. The method of claim 12 , wherein the second pair of RF excitation pulses of the first pulse sequence are applied at a frequency detuned from a resonance frequency of the magneto-optical defect center material.

16. The method of claim 12 , wherein the pulse width of the second pair of RF excitation pulses is associated with a fluorescence null point of the magneto-optical defect center material.

17. The method of claim 12 , wherein the second time period is associated with a fluorescence null point of the magneto-optical defect center material.

18. The method of claim 12 , wherein the pulse width of the second pair of RF excitation pulses and the second time period is associated with a fluorescence null point of the magneto-optical defeat center material.

19. The method of claim 18 , wherein the pulse width of the first pair of RF excitation pulses and the first time period is associated with a fluorescence low point of the magneto-optical defect center material.defect center material.

20. The method of claim 12 , wherein the first pair of RF excitation pulses is applied followed by the second pair of RF excitation pulses.

21. A magnetic detection system compris

Assignees

• Lockheed Corp

Inventors

• Bruce Gregory Scott
• Manickam Arul
• Kaup Peter G

Classifications

• G01R33/032

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

• G01R33/26 Primary

  using optical pumping · CPC title