Pulsed Pump Magnetometer Arrays for Unshielded Biomagnetic Sensing
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Solution Overview
Problem
Biomagnetic measurements are significantly degraded by magnetic noise when magnetometers are operated without shielding, making it difficult to obtain high-quality readings in unshielded environments.
Innovation Solution
The use of an array of pulsed pump magnetometers (PPMs) with atomic vapor cells and pulsed or continuous probe lasers, capable of operating in a wide range of background magnetic fields, allows for high-quality biomagnetic signal detection and noise cancellation, even in magnetically noisy conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If magnetometers are operated without magnetic shielding, then device complexity and cost are reduced, but measurement precision is significantly degraded by magnetic noise
Solution Approach 1:
The patent extracts and removes the magnetic shielding component from the measurement system, operating magnetometers in an unshielded environment. This is achieved by using multiple magnetometers in a gradiometer configuration that inherently rejects magnetic noise without requiring physical shielding, thus simplifying the device while maintaining measurement precision.
Solution Approach 2:
The patent introduces an intermediary processing approach using gradiometer algorithms that compute the difference between adjacent magnetometer readings. This mathematical intermediary operation eliminates the need for physical shielding by using signal processing to reject common-mode magnetic noise while preserving biomagnetic signals.
2Measurement precision
If multiple magnetometers are used in an array configuration, then noise rejection capability is improved through gradiometer processing, but device complexity increases
Solution Approach 1:
The patent merges multiple magnetometer readings through gradiometer processing, combining the outputs of adjacent sensors to compute magnetic field differences. This merging operation enhances noise rejection by eliminating common-mode noise while preserving spatially varying biomagnetic signals, achieving improved precision without requiring complex individual sensors.
Solution Approach 2:
The patent segments the measurement system into multiple distributed magnetometers positioned at different locations. This segmentation allows each sensor to independently measure local magnetic fields, and the differences between these segmented measurements provide noise rejection capability while keeping individual sensor complexity low.
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
PPMs provide higher sensitivity and noise rejection, enabling accurate localization and imaging of biomagnetic sources in unshielded environments by decorrelating and modeling noise, and converting light signals to total magnetic field measurements.
Implementation Method 1
at least one atomic vapor cell with at least one pulsed pump laser and at least one probe laser
Implementation Method 2
at least one pulsed pump laser and at least one probe laser which is pulsed or operated continuously
Data Source
AI summary
The pulsed pump magnetometer (PPM) is a new type of magnetometer with much higher dynamic range, linearity, and sensitivity than all other types of magnetometers. These features allow more faithful subtracting and cancelling sources of magnetic noise, enabling high quality biomagnetic measurements. Using an array of PPM sensors enables high quality measurements of biomagnetic signals even in magnetically noisy, real-world conditions like medical offices. Arrays of PPM sensors improve upon pulsed magnetic gradiometers in providing higher sensitivity per sensor and superior noise rejection through noise decorrelation and covariance modeling. Arrays of PPM sensors enable localization and imaging of biomagnetic sources.