Differential Magnetic Field Sensing With Reference Sensor Crystals
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Solution Overview
Problem
Existing quantum-based magnetic field sensors face limitations in synchronicity of sensor signals when used in environments with ambient noise, leading to ineffective suppression of background magnetic fields.
Innovation Solution
A device utilizing two sensor crystals arranged at different distances with synchronized excitation and measurement conditions to measure the difference in magnetic fields, employing a Ramsey protocol to enhance signal-to-noise ratio by suppressing ambient noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a magnetic shield made of mu-metal is placed around the sensor and signal source, then ambient magnetic noise is suppressed, but the device becomes very expensive, heavy, and severely limits possible measurements
Solution Approach 1:
The patent introduces a second sensor crystal as an intermediary element that acts as a reference sensor to measure only the ambient magnetic noise. By comparing the signal from the first sensor crystal (which measures both signal and noise) with the second sensor crystal (which measures only noise), the system can subtract the noise component and extract the useful signal without requiring physical magnetic shielding
Solution Approach 2:
The second sensor crystal creates a copy of the ambient noise measurement. This copy is then subtracted from the first sensor's measurement to eliminate the noise. The copying approach allows noise rejection without the need for bulky mu-metal shields, reducing device complexity while maintaining noise suppression effectiveness
2Object-affected harmful factors
If two autonomous sensors with individual signal evaluation are used to suppress ambient noise, then noise suppression is achieved, but the synchronicity of sensor signals is lost, resulting in only moderate noise suppression
Solution Approach 1:
The patent merges the signal evaluation process by having a single evaluation unit process signals from both sensor crystals. This centralized evaluation ensures that both signals are processed with identical algorithms and timing references, maintaining perfect synchronicity. The combined processing allows for precise differential measurement where the noise components cancel out while preserving the useful signal
Solution Approach 2:
The single signal evaluation unit serves multiple functions: it processes signals from both sensor crystals, performs differential calculation to reject noise, and maintains synchronicity across both measurement channels. This multi-functional design ensures that both sensors operate as a coordinated system rather than independent units, achieving optimal noise suppression
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
Achieves ideal common mode rejection and improved signal-to-noise ratio for measuring magnetic fields of interest by eliminating temporally homogeneous background noise.
Implementation Method 1
This takes advantage of the fact that under the influence of an external magnetic field, the energy levels of certain spin states of unpaired electrons split, the so-called Zeeman effect.
Implementation Method 2
The quantum state is prepared by optical excitation and interaction with a static magnetic field and a dynamic magnetic field
Implementation Method 3
The information stored in the spin system is optically read out by detecting the fluorescence rates of the NV center, which are dependent on the spin state.
Implementation Method 4
a field generating means (130) for generating a magnetic field, wherein the first and the second sensor crystal (10, 20) are arranged in the magnetic field
Data Source
AI summary
A device for determining a magnetic field of interest at a measurement location. The device includes first and second sensor crystals having color centers, the first sensor crystal being arranged at the measurement location, and the second being arranged at a distance therefrom. An excitation light generator generates a pulsed excitation light which irradiates the first and second sensor crystals. A field generator generates a magnetic field. The first and the second sensor crystal are arranged in the magnetic field. A measuring arrangement detects a fluorescent light emanating from the first and the second sensor crystal. The device applies the same magnetic field and excitation light to the first and second sensor crystals and directly measures the difference between the magnetic fields at the respective locations of the first and second sensor crystals to suppress a temporally variable but spatially homogeneous background magnetic field at the measurement location.