Suppression of Amplitude and Phase Errors in Optically Pumped Magnetometers Using Dual-PI Closed-Loop Control

Optically pumped magnetometer (OPM) has gained popularity as a viable alternative to the superconducting quantum interference device (SQUID) for biomagnetic measurements. However, the presence of amplitude and phase errors in the OPM can degrade the signal quality of, e.g., magnetoencephalography (M...

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Bibliographic Details
Published in:IEEE transactions on instrumentation and measurement 2024, Vol.73, p.1-12
Main Authors: Long, Tengyue, Song, Xinda, Duan, Zhaoxin, Suo, Yuchen, Wu, Zhendong, Jia, Le, Han, Bangcheng
Format: Article
Language:English
Subjects:
Amplitude and phase errors
Amplitudes
Atomic measurements
Biomagnetism
Closed loops
dual-PI closed-loop control (DPCC)
Errors
Feedback control
Localization
Magnetic field measurement
Magnetic fields
Magnetoencephalography
magnetoencephalography (MEG)
Magnetometers
Optical pumping
optically pumped magnetometer (OPM)
Sensitivity
Signal quality
spin-exchange relaxation-free (SERF)
Superconducting magnets
Superconducting quantum interference devices
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Summary:Optically pumped magnetometer (OPM) has gained popularity as a viable alternative to the superconducting quantum interference device (SQUID) for biomagnetic measurements. However, the presence of amplitude and phase errors in the OPM can degrade the signal quality of, e.g., magnetoencephalography (MEG) signals. This study presents a dual-PI closed-loop control (DPCC) method aimed at suppressing amplitude and phase errors of the OPM when operated in the spin-exchange relaxation-free (SERF) regime, thereby enhancing MEG localization accuracy. The main sources of the amplitude and phase errors in the OPM are identified through a theoretical analysis of the inertial element characteristics and static residual magnetic fields. The experimental results demonstrate that the utilization of DPCC for the OPM reduces the amplitude and phase errors in static MEG measurements by 94.2% and 95.6%, respectively. At a residual magnetic field of 6.5 nT, the amplitude and phase errors are further suppressed by 97.8% and 87.2%, respectively. Furthermore, the fluctuation of the residual magnetic field is reduced by a factor of 25, significantly enhancing the robustness of the OPM. This straightforward and effective arrangement of the OPM holds promise in the field of biomagnetism and is expected to enhance the localization and calibration accuracy of OPM-based MEG (OPM-MEG) systems.
ISSN:0018-9456
1557-9662
DOI:10.1109/TIM.2023.3341139