Wide dynamic range SQUID magnetometer with noise cancellation for magnetocardiogram without magnetically shielded room

摘要: SQUID magnetometers are widely used for biomagnetic measurements, such as magnetocardiogram (MCG) and magnetoencephalogram (MEG). In present measurement, a magnetically shielded room (MSR) is to reduce environment magnetic noise. However, the MSR very expensive heavy. recent years, several groups developed with digitally controlled flux-locked loop (FLL) MCG measurements without [1], [2]. These systems were flux quanta counting (FQC) method extend dynamic range. On other hand, there problem that measured bad signal-to-noise ratio (SNR). The direct-feedback gradiometer was proposed noise [3]. This feedback of reference magnetometer applied sensing magnetometer. Because have operate stably, this only in MSR.