Variable Dynamic Range Optical Magnetometers for Unshielded Measurement
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Solution Overview
Problem
Conventional magnetic field measurement systems, such as SERF magnetometers, are limited by their intrinsic dynamic range and require costly and bulky shielding to operate effectively, making them unsuitable for measuring Earth's magnetic field or neural signals in unshielded environments.
Innovation Solution
A magnetic field measurement system comprising an array of magnetometers with a controller that adjusts the dynamic range and sensitivity by generating a compensation field, allowing operation in various modes to accommodate changing ambient magnetic fields, using alkali metal vapor and active electromagnets to suppress background noise and enable measurement of biologically generated fields outside shielded environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If passive and active shielding are employed to enable SERF magnetometer operation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system dynamically adjusts the operating mode of individual magnetometers based on real-time ambient magnetic field conditions. Each magnetometer can switch between SERF mode (for low field, high precision) and non-SERF mode (for high field, lower precision), allowing the system to adapt to changing environmental conditions without requiring permanent shielding infrastructure
Solution Approach 2:
The invention changes the operational parameters of the magnetometers by adjusting their operating modes. By controlling which magnetometers operate in SERF mode versus non-SERF mode, the system can optimize measurement precision for different ambient field conditions, effectively replacing the need for fixed shielding with dynamic parameter adjustment
2Measurement precision
If SERF magnetometer measurement mode is used, then measurement precision is improved, but adaptability deteriorates due to limited dynamic range
Solution Approach 1:
The system segments the array of magnetometers into different operational groups. Some magnetometers operate in SERF mode for high-precision low-field measurements, while others operate in non-SERF mode for broader dynamic range coverage. This segmentation allows the system to simultaneously achieve high precision and broad adaptability across different field conditions
Solution Approach 2:
Each magnetometer in the array is designed to be multi-functional, capable of operating in both SERF and non-SERF modes. This universality allows the system to handle a wide variety of measurement scenarios, from ultra-low field neural signals to Earth's magnetic field, using the same hardware platform
3Measurement precision
If the number of magnetometers operating in measurement mode is increased, then sensitivity is improved, but dynamic range decreases
Solution Approach 1:
The system dynamically controls the number and configuration of magnetometers operating in measurement mode based on the ambient magnetic field conditions. When high sensitivity is needed for weak signals, more magnetometers operate in SERF mode. When broader dynamic range is needed for stronger fields, the system adjusts which magnetometers remain in measurement mode, optimizing the trade-off in real-time
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
Enables accurate measurement of magnetic fields in unshielded environments, including neural signals, by dynamically adjusting the compensation field to maintain magnetometers in the SERF mode, thereby overcoming the limitations of conventional systems in terms of dynamic range and sensitivity.
Implementation Method 1
The magnetometers utilize alkali metal vapor and the measurement mode is a spin-exchange-relaxation-free (SERF) mode
Implementation Method 2
at least one magnetic field generator with the at least one magnetic field generator configured to generate a compensation field across the array of magnetometers
Data Source
AI summary
A magnetic field measurement system includes an array of magnetometers; at least one magnetic field generator configured to generate a compensation field across the array of magnetometers; and a controller coupled to the magnetometers and the at least one magnetic field generator and configured for adjusting a dynamic range and sensitivity of the array by adjusting a spatial variation of the compensation field to alter which of the magnetometers of the array operate in a measurement mode. Another magnetic field measurement system utilizes at least one magnetometer instead of the array. The controller is configured for adjusting a dynamic range and sensitivity of the array by adjusting a spatial variation of the compensation field to alter which of multiple domains within the at least one magnetometer operate in the measurement mode.