APPARATUS AND METHOD FOR HIGH SENSITIVITY MAGNETOMETRY MEASUREMENT AND SIGNAL PROCESSING IN A MAGNETIC DETECTION SYSTEM

• US 20170139017A1
• Filed: 01/30/2017
• Published: 05/18/2017
• Est. Priority Date: 01/23/2015
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Egan, Laird Nicholas, Coar, David Nelson, Russo, Jon C.
• Granted Patent: US 10,466,312 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 21/63 optically excited
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: G01R 33/032 using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect

Abstract

A system for magnetic detection may include a nitrogen vacancy (NV) diamond material, a radio frequency (RF) excitation source, an optical excitation source, an optical detector, a magnetic field generator, and a controller. The controller may control the excitation sources to apply a first pulse sequence. The controller may receive a first light detection signal due to the first pulse sequence, measure first and second values of the first light detection signal at first and second reference periods, and compute a first measurement. The controller may further control the excitation sources to apply a second pulse sequence, receive a second light detection signal due to the second pulse sequence, measure first and second values of the second light detection signal at first and second reference periods, and compute a second measurement. The first and second measurements may be based on high and low resonance frequencies of the NV diamond material.

Claims

1. A system for magnetic detection, comprising:

a magneto-defect center material comprising a plurality of defect centers;

a radio frequency (RF) excitation source configured to provide RF excitation to the magneto-defect center material;

an optical excitation source configured to provide optical excitation to the magneto-defect center material;

an optical detector configured to receive an optical signal emitted by the magneto-defect center material;

a magnetic field generator configured to generate a magnetic field applied to the magneto-defect center material; and

a controller configured to;

control the optical excitation source and the RF excitation source to apply a first pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-defect center material;

receive a first light detection signal from the optical detector based on an optical signal emitted by the magneto-defect center material due to the first pulse sequence;

measure a first value of the first light detection signal at a first reference period, the first reference period being before a period of the first light detection signal associated with the two RF excitation pulses of the first pulse sequence provided to the magneto-defect center material;

measure a second value of the first light detection signal at a second reference period, the second reference period being after the period of the first light detection signal associated with the two RF excitation pulses of the first pulse sequence provided to the magneto-defect center material;

compute a first measurement based on the measured first and second values of the first light detection signal;

control the optical excitation source and the RF excitation source to apply a second pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-defect center material;

receive a second light detection signal from the optical detector based on an optical signal emitted by the magneto-defect center material due to the second pulse sequence;

measure a first value of the second light detection signal at a first reference period, the first reference period being before a period of the second light detection signal associated with the two RF excitation pulses of the second pulse sequence provided to the magneto-defect center material;

measure a second value of the second light detection signal at a second reference period, the second reference period being after the period of the second light detection signal associated with the two RF excitation pulses of the second pulse sequence provided to the magneto-defect center material; and

compute a second measurement based on the measured first and second values of the second light detection signal,

wherein the first measurement is based on a high resonance frequency of the magneto-defect center material, and

wherein the second measurement is based on a low resonance frequency of the magneto-defect center material.

2. The system of claim 1, wherein the high resonance frequency and the low resonance frequency are resonance frequencies associated with an axis of a defect center of the magneto-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-defect center material based on the first and second measurements.

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

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

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

7. The system of claim 1, wherein the controller is configured to apply one of the two optical excitation pulses, followed by the two RF excitation pulses, and followed by the other of the two optical excitation pulses during each of the first pulse sequence and the second pulse sequence.

8. The system of claim 1, wherein the controller is further configured to measure a third value of the first light detection signal at a signal period, the signal period being after the first reference period and before the second reference period of the first light detection signal.

9. The system of claim 8, wherein the controller is further configured to compute the first measurement based on a difference between the average of the first and second values and the third value of the first light detection signal.

10. A system for magnetic detection, comprising:

a magneto-defect center material comprising a plurality of defect centers;

a radio frequency (RF) excitation source configured to provide RF excitation to the magneto-defect center material;

an optical excitation source configured to provide optical excitation to the magneto-defect center material;

an optical detector configured to receive an optical signal emitted by the magneto-defect center material;

a magnetic field generator configured to generate a magnetic field applied to the magneto-defect center material; and

a controller configured to;

control the optical excitation source and the RF excitation source to apply a pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-defect center material;

receive a light detection signal from the optical detector based on an optical signal emitted by the magneto-defect center material due to the pulse sequence;

measure a first value of the light detection signal at a first reference period, the first reference period being before a period of the light detection signal associated with the two RF excitation pulses provided to the magneto-defect center material;

measure a second value of the light detection signal at a second reference period, the second reference period being after the period of the light detection signal associated with the two RF excitation pulses provided to the magneto-defect center material; and

compute a measurement signal based on the measured first and second values.

11. The system of claim 10, wherein the controller is further configured to measure the first value and the second value based on an average of values of the light detection signal within the first reference period and the second reference period.

12. The system of claim 10, wherein the controller is further configured to compute the measurement signal based on the average of the first value and the second value.

13. The system of claim 10, wherein the controller is further configured to measure a third value of the light detection signal at a signal period, the signal period being after the first reference period and before the second reference period.

14. The system of claim 13, wherein the controller is further configured to compute the measurement signal based on a difference between the average of the first and second values and the third value.

15. The system of claim 10, wherein the first reference period is associated with one of the two optical excitation pulses and the second reference period is associated with the other of the two optical excitation pulses.

16. A system for magnetic detection, comprising:

a magneto-defect center material comprising a plurality of magneto-defect centers;

a radio frequency (RF) excitation source configured to provide RF excitation to the magneto-defect center material;

an optical excitation source configured to provide optical excitation to the magneto-defect center material;

an optical detector configured to receive an optical signal emitted by the magneto-defect center material;

a magnetic field generator configured to generate a magnetic field applied to the magneto-defect center material; and

a controller configured to;

control the optical excitation source and the RF excitation source to apply a first pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-defect center material;

receive a first light detection signal from the optical detector based on an optical signal emitted by the magneto-defect center material due to the first pulse sequence;

compute a first measurement based on the first light detection signal;

control the optical excitation source and the RF excitation source to apply a second pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-defect center material;

receive a second light detection signal from the optical detector based on an optical signal emitted by the magneto-defect center material due to the second pulse sequence; and

compute a second measurement based on the second light detection signal,

wherein the first measurement is based on a high resonance frequency of the magneto-defect center material, and

wherein the second measurement is based on a low resonance frequency of the magneto-defect center material.

17. The system of claim 16, wherein the high resonance frequency and the low resonance frequency are resonance frequencies associated with an axis of a defect center of the magneto-defect center material.

18. The system of claim 16, wherein the two RF excitation pulses of the first pulse sequence are applied at a frequency detuned from the high resonance frequency of the magneto-defect center material.

19. The system of claim 16, wherein the two RF excitation pulses of the second pulse sequence are applied at a frequency detuned from the low resonance frequency of the magneto-defect center material.

20. The system of claim 16, wherein the controller is further configured to compute a change in an external magnetic field acting on the magneto-defect center material based on the first and second measurements.

21. A system for magnetic detection, comprising:

a magneto-optical defect center material comprising a plurality of magneto-optical defect centers;

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 magnetic field generator configured to generate a magnetic field applied to the magneto-optical defect center material; and

a controller configured to;

control the optical excitation source and the RF excitation source to apply a plurality of pulse sequences to the magneto-optical defect center material, each of the plurality of pulse sequences comprising two optical excitation pulses and an RF excitation pulse, wherein a time period of application of the RF excitation pulse is varied among each of the plurality of pulse sequences;

receive a plurality of light detection signals from the optical detector based on an optical signal emitted by the magneto-optical defect center material due to the plurality of pulse sequences;

measure a first value of each of the plurality of light detection signals at a first reference period, the first reference period being before a period associated with the RF excitation pulse of each of the plurality of pulse sequences;

measure a second value of each of the plurality of light detection signals at a second reference period, the second reference period being after the period associated with the RF excitation pulse of each of the plurality of pulse sequences;

compute a plurality of measurement signals based on the plurality of measured first and second values; and

calculate a frequency of the plurality of measurement signals.

22. The system of claim 21, wherein the frequency is a resonant Rabi frequency.

23. The system of claim 21, wherein the RF excitation source is a microwave antenna.

24. The system of claim 23, wherein the microwave antenna is a small loop antenna.

25. The system of claim 24, wherein the small loop antenna comprises a loop having a diameter of about 2 mm.

26. The system of claim 23, wherein the microwave antenna is configured to provide a microwave power of at least 10 watts.

27. The system of claim 21, wherein the controller is configured to apply one of the two optical excitation pulses, followed by the RF excitation pulse, and followed by the other of the two optical excitation pulses during each of the plurality of pulse sequences.

28. The system of claim 27, wherein the controller is configured to apply a window between the one of the two optical excitation pulses and the RF excitation pulse during each of the plurality of pulse sequences, the window being a time period in which no excitation or optical excitation is applied to the magneto-optical defect center material.

29. The system of claim 21, wherein the controller is further configured to identify a first minimum of the plurality of measurement signals.

30. A system for magnetic detection, comprising:

a magneto-optical defect center material comprising a plurality of magneto-optical defect centers;

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 magnetic field generator configured to generate a magnetic field applied to the magneto-optical defect center material; and

a controller configured to;

control the optical excitation source and the RF excitation source to apply a plurality of pulse sequences to the magneto-optical defect center material, each of the plurality of pulse sequences comprising two optical excitation pulses and two RF excitation pulses, wherein a time period between application of the two RF excitation pulses is varied among each of the plurality of pulse sequences;

receive a plurality of light detection signals from the optical detector based on an optical signal emitted by the magneto-optical defect center material due to the plurality of pulse sequences;

measure a first value of each of the plurality of light detection signals at a first reference period, the first reference period being before a period associated with the RF excitation pulse of each of the plurality of pulse sequences;

measure a second value of each of the plurality of light detection signals at a second reference period, the second reference period being after the period associated with the RF excitation pulse of each of the plurality of pulse sequences;

compute a plurality of measurement signals based on the plurality of measured first and second values; and

calculate a decay time of the plurality of measurement signals.

31. The system of claim 30, wherein the two RF excitation pulses of each of the plurality of pulse sequences are applied at a frequency of about 10 MHz.

32. A system for magnetic detection having a magneto-optical defect center material comprising a plurality of magneto-optical defect centers, comprising:

means for providing RF excitation to the magneto-optical defect center material;

means for providing optical excitation to the magneto-optical defect center material;

means for receiving an optical signal emitted by the magneto-optical defect center material;

means for generating a magnetic field applied to the magneto-optical defect center material; and

means for applying a pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-optical defect center material;

means for receiving a light detection signal based on an optical signal emitted by the magneto-optical defect center material due to the pulse sequence;

means for measuring a first value of the light detection signal at a first reference period, the first reference period being before a period of the light detection signal associated with the two RF excitation pulses provided to the magneto-optical defect center material;

means for measuring a second value of the light detection signal at a second reference period, the second reference period being after the period of the light detection signal associated with the two RF excitation pulses provided to the magneto-optical defect center material; and

means for computing a measurement signal based on the measured first and second values.

33. A method for detecting a magnetic field acting on a magneto-optical defect center material comprising a plurality of magneto-optical defect centers, comprising:

controlling an optical excitation source and an RF excitation source to apply a pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-optical defect center material;

receiving a light detection signal from an optical detector based on an optical signal emitted by the magneto-optical defect center material due to the pulse sequence;

measuring a first value of the light detection signal at a first reference period, the first reference period being before a period of the light detection signal associated with the two RF excitation pulses provided to the magneto-optical defect center material;

measuring a second value of the light detection signal at a second reference period, the second reference period being after the period of the light detection signal associated with the two RF excitation pulses provided to the magneto-optical defect center material; and

computing a measurement signal based on the measured first and second values.

34. The method of claim 33, further comprising computing the measurement signal based on the average of the first value and the second value.

35. The method of claim 33, further comprising measuring a third value of the light detection signal at a signal period, the signal period being after the first reference period and before the second reference period.

36. The method of claim 35, further comprising computing the measurement signal based on a difference between the average of the first and second values and the third value.

37. A system for magnetic detection having a magneto-optical defect center material comprising a plurality of magneto-optical defect centers, comprising:

means for providing RF excitation to the magneto-optical defect center material;

means for providing optical excitation to the magneto-optical defect center material;

means for receiving an optical signal emitted by the magneto-optical defect center material;

means for generating a magnetic field applied to the magneto-optical defect center material; and

means for applying a first pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-optical defect center material;

means for receiving a first light detection signal based on an optical signal emitted by the magneto-optical defect center material due to the first pulse sequence;

means for computing a first measurement based on the first light detection signal;

means for applying a second pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-optical defect center material;

means for receiving a second light detection signal based on an optical signal emitted by the magneto-optical defect center material due to the second pulse sequence; and

means for computing a second measurement based on the second light detection signal,

wherein the first measurement is based on a high resonance frequency of the magneto-optical defect center material, and

wherein the second measurement is based on a low resonance frequency of the magneto-optical defect center material.

38. A method for detecting a magnetic field acting on a magneto-optical defect center material comprising a plurality of magneto-optical defect centers, comprising:

controlling an optical excitation source and an RF excitation source to apply a first pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-optical defect center material;

receiving 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;

computing a first measurement based on the first detection signal;

controlling the optical excitation source and the RF excitation source to apply a second pulse sequence comprising two optical excitation pulses and two RF excitation pulses to the magneto-optical defect center material;

receiving 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

computing a second measurement based on the second light detection signal,

wherein the first measurement is based on a high resonance frequency of the magneto-optical defect center material, and

wherein the second measurement is based on a low resonance frequency of the magneto-optical defect center material.

39. The method of claim 38, wherein the high resonance frequency and the low resonance frequency are resonance frequencies associated with an axis of a magneto-optical defect center of the magneto-optical defect center material.

40. The method of claim 38, further comprising computing a change in an external magnetic field acting on the magneto-optical defect center material based on the first and second measurements.