Compact Optically Pumped Magnetometer with Pump-Probe Configuration
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Solution Overview
Problem
Conventional magnetic field measurement systems, particularly those using optically pumped magnetometers (OPMs), face limitations in spatial resolution due to bulky and expensive cryogenic cooling requirements and thermal management issues, making them unsuitable for mobile or wearable devices, and struggle with magnetic cross-talk and low sensitivity in higher magnetic fields.
Innovation Solution
A compact optically pumped magnetometer design employing a pump-probe configuration with identical light sources and detectors, utilizing spatial filtering and a quarter wave plate to enhance optical pumping and probing, allowing for improved spatial resolution and operation in unshielded environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If superconducting quantum interference devices (SQUIDs) are used for MEG measurement, then magnetic field sensitivity is improved, but device size increases and requires cryogenic cooling which is bulky and expensive
Solution Approach 1:
The patent replaces the mechanical cryogenic cooling system of SQUIDs with an optically pumped magnetometer system that operates at room temperature. The invention uses optical pumping with laser diodes to polarize vapor in a small glass cell, eliminating the need for bulky cryogenic equipment while achieving comparable or superior magnetic field sensitivity through optical detection methods.
2Volume of moving object
If a single vapor cell is used inside a 1 to 2 cm package, then device compactness is improved, but spatial resolution beyond this range is prevented or hindered
Solution Approach 1:
The patent divides the measurement system into multiple independent vapor cells, each capable of detecting magnetic fields at different spatial locations. By using an array of segmented magnetometers rather than a single cell, the system achieves both compactness and improved spatial resolution, as each cell can be positioned to detect fields from specific neural sources.
Solution Approach 2:
The invention transitions from a single-point measurement to a distributed array of measurement points arranged in specific geometric configurations. This dimensional expansion allows the system to capture spatial variations in magnetic field strength and direction, enabling source localization and improving spatial resolution while maintaining compact form factor.
3Volume of moving object
If discrete magnetometers are used, then device portability is improved, but thermal management and magnetic cross talk pose practical limitations to achieving high spatial resolution
Solution Approach 1:
The patent merges multiple vapor cells into a closely spaced array with shared optical components and integrated electronics. This consolidation reduces thermal management challenges by distributing heat loads and enables magnetic cross-talk compensation through differential measurement techniques, achieving high spatial resolution while maintaining portability.
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
The compact design enables high spatial resolution magnetic field measurements in unshielded environments, overcoming the limitations of cryogenic cooling and thermal management, and achieving sensitive magnetic field detection without the need for magnetically shielded rooms.
Implementation Method 1
a pump light beam from the at least one light source illuminating the vapor cell
Implementation Method 2
a probe light beam from the at least one light source subsequently illuminating the vapor cell
Implementation Method 3
a quarter wave plate disposed between the lens and the vapor cell
Implementation Method 4
a mirror configured to receive the pump light beam and probe light beam after passing through the vapor cell and reflect the pump light beam and probe light beam back through the vapor cell
Implementation Method 5
at least one detector configured to receive the probe light beam reflected by the mirror
Data Source
AI summary
An optically pumped magnetometer includes a vapor cell; at least one light source configured to produce a pump light beam and a probe light beam; a lens disposed between the at least one light source and the vapor cell; a quarter wave plate disposed between the lens and the vapor cell; a mirror configured to receive the pump light beam and probe light beam after passing through the vapor cell and reflect the pump light beam and probe light beam back through the vapor cell, the quarter wave plate, and the lens; and at least one detector configured to receive the probe light beam reflected by the mirror.