Phase-Coherent Magnetometer Excitation During Frequency Switching
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Solution Overview
Problem
Existing voltage-controlled oscillator (VCO)-based systems for generating pulsed excitation signals in electron spin resonance (ESR) and nuclear magnetic resonance (NMR) spectroscopy suffer from phase loss during frequency switching, leading to reduced measurement accuracy and coherence issues.
Innovation Solution
A method involving cyclic switching of the excitation signal between resonance and idle frequencies, with phase alignment to a continuous reference signal, using voltage-controlled oscillators and secondary oscillators for phase coherence, ensuring phase-coherent excitation and readout pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If voltage-controlled oscillators are used to generate pulsed excitation signals in ESR and NMR spectroscopy, then the system becomes more compact and cost-effective, but phase loss occurs during frequency switching leading to reduced measurement accuracy
Solution Approach 1:
A phase reference signal is introduced as an intermediary element that mediates between the voltage-controlled oscillator and the measurement process. This reference signal serves as a stable temporal marker that allows the system to track and correct phase shifts occurring during frequency switching, thereby maintaining measurement accuracy while using compact VCO-based architecture
Solution Approach 2:
The system implements feedback by continuously monitoring the phase relationship between the excitation signal and the reference signal. Based on this feedback information, the system can adjust timing parameters and compensate for phase losses, ensuring that measurement accuracy is maintained despite the inherent phase instability of voltage-controlled oscillators during frequency transitions
2Productivity
If the operating frequency of the excitation signal is switched between resonance and idle frequencies, then pulsed excitation is achieved, but phase coherence is lost during switching
Solution Approach 1:
The reference signal is generated and maintained continuously before, during, and after frequency switching operations. By having the reference signal ready in advance and maintaining it throughout the switching process, the system establishes a stable phase reference framework that enables coherent reconstruction of the excitation pulses even though the actual excitation frequency changes
Solution Approach 2:
The system employs periodic reference signals that are synchronized with the pulsed excitation scheme. This periodic reference structure allows the system to establish consistent phase relationships at regular intervals, enabling coherent signal processing and maintaining phase coherence across multiple excitation cycles despite frequency switching between pulses
3Device complexity
If VCO-based systems are used for ESR detection, then integration into chip-based systems is enabled, but the limited quality factor requires lower threshold oscillation current
Solution Approach 1:
The system uses the same inductive assembly that serves as the ESR sensor to also generate the excitation signal. This self-service approach eliminates the need for separate high-current excitation sources, allowing the system to operate at lower current thresholds while maintaining sufficient excitation capability for chip-integrated applications
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 enhances measurement accuracy and speed by maintaining phase coherence, allowing for more precise and rapid magnetic field measurements in ESR and NMR spectroscopy.
Implementation Method 1
an inductive assembly is excited by an excitation signal to provide a second magnetic field at a sample location
Implementation Method 2
an operating phase of the excitation signal is aligned to an excitation reference phase of an excitation reference signal
Implementation Method 3
using voltage-controlled oscillators and secondary oscillators for phase coherence
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for generating and/or detecting the magnetization of a sample (2) at a sample location (3), in particular for investigating the sample (2) by means of electron spin resonance spectroscopy or for measuring a first magnetic field (B0) acting on the sample (2) at the sample location (3). An inductive assembly (5) is excited by an excitation signal (S) to provide a second magnetic field (B1) at the sample location (3), wherein the excitation signal (S) is cyclically switched between an excitation period (TX), in which an operating frequency (fESR) of the excitation signal (S) has a sample-specific resonance frequency (fres), and an idle period (RX), in which the operating frequency (fESR) of the excitation signal (S) has an idle frequency (fidle) different from the resonance frequency (fres).It is provided that an operating phase of the excitation signal (S) is aligned, at least during the switching of the operating frequency (fESR) from the open-circuit frequency (fidle) to the resonant frequency (fres), to an excitation reference phase of an excitation reference signal (Sref) separate from the excitation signal (S), preferably continuously generated.