Abstract
SQUID magnetometers are widely used for biomagnetic measurements, such as magnetocardiogram (MCG) and magnetoencephalogram (MEG). In present biomagnetic measurement, a magnetically shielded room (MSR) is used to reduce environment magnetic noise. However, the MSR is very expensive and heavy. In recent years, several groups developed SQUID magnetometers with digitally controlled flux-locked loop (FLL) for MCG measurements without the MSR [1], [2]. These systems were used the flux quanta counting (FQC) method to extend the dynamic range. On the other hand, there is a problem that MCG measured without the MSR is very bad signal-to-noise ratio (SNR). The direct-feedback gradiometer method was proposed to reduce environment magnetic noise [3]. This method is that the feedback flux of the reference magnetometer is applied to sensing magnetometer. Because the magnetometers have to operate stably, this method is used only in the MSR.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
