Ramsey Pulse Magnetometry for Drift Reduction

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Solution Overview

Problem

Mobile magnetometers, such as those using nitrogen-vacancy (NV) centers in diamond lattices, face inaccuracies under large dynamic range excursions, limiting their use in applications like magnetic navigation due to sources like gain changes, dynamic range extension errors, and interpolation inaccuracies.

Innovation Solution

The system employs a magneto-optical defect center material with a series of Ramsey pulse sequences and shifted magnetometry adaptive cancelation (SMAC) techniques, involving multiple pairs of RF excitation pulses with varying phase differences, to generate combined magnetometry curves that are resilient to gain changes and interpolation errors, enhancing sensitivity and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If mobile magnetometers are used for magnetic detection, then portability and compact size are achieved, but measurement precision deteriorates under large dynamic range excursions

Engineering Contradiction:

Improvesensor sizeVSAvoidmagnetic field measurement accuracy

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent divides the magnetometry measurement into multiple discrete frequency point measurements. By segmenting the dynamic range into smaller frequency steps and measuring each point individually, the system achieves high precision at each point while maintaining the ability to cover a large overall dynamic range through the combination of multiple measurements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs periodic Ramsey pulse sequences at different RF excitation frequencies to probe the magneto-optical defect center material. By periodically applying these pulse sequences at multiple frequency points and combining the results, the system achieves both portability and high measurement precision across large dynamic ranges.

Inventive Principle:

Principle #19Periodic action

2Adaptability or versatility

If dynamic range extension techniques are applied, then the measurement range is increased, but interpolation errors increase

Engineering Contradiction:

Improvedynamic rangeVSAvoidinterpolation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary measurements at multiple discrete frequency points across the dynamic range before final magnetometry determination. By pre-sampling the response at various RF excitation frequencies and storing these reference measurements, the system enables accurate interpolation during actual operation without sacrificing precision, as the interpolation is based on pre-acquired high-quality reference data.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If gain changes occur in the detection system, then sensitivity varies, but measurement reliability deteriorates

Engineering Contradiction:

ImprovesensitivityVSAvoidmeasurement consistency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where measurements taken at multiple frequency points are combined to determine the final magnetometry result. This feedback approach allows the system to compensate for gain changes by using the relative information from multiple frequency measurements, maintaining measurement consistency and reliability even when sensitivity varies due to gain fluctuations.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach improves the dynamic range and reduces interpolation errors, making the system more accurate and reliable for magnetic field detection, particularly in applications requiring high precision like magnetic navigation.

Implementation Method 1

magnetic detection using a magneto-optical defect center material comprising a plurality of defect centers

Methodology Applied

Scientific EffectMagneto-optical effect: Magneto-Optic Effects

Implementation Method 2

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

Methodology Applied

Scientific EffectOptical detection: Photoelectric Effect

Implementation Method 3

apply a first Ramsey pulse sequence to the magneto-optical defect center material comprising a first pair of RF excitation pulses having a first phase difference

Methodology Applied

Scientific EffectRF excitation: Electromagnetic Induction

Data Source

PatentUS11187765B2Apparatus and method for lower magnetometer drift with increased accuracy

Publication Date: 2021.11.30 LOCKHEED MARTIN CORP

AI summary

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 Ramsey pulse sequence pair or a shifted magnetometry adapted cancellation (SMAC) pair to detect and measure the magnetic field acting on the system. Utilizing a pair of magnetic measurements that are approximately in quadrature improves the dynamic range and accuracy of the magnetic detection.