A feed-forward measurement scheme for periodic noise suppression in atomic magnetometry

Abstract

We present an unshielded, double-resonance magnetometer in which we have implemented a feedforward measurement scheme in order to suppress periodic magnetic noise arising from, and correlated with, the mains electricity alternating current (AC) line. The technique described here uses a single sensor to track ambient periodic noise and feed forward to suppress it in a subsequent measurement. This feed forward technique has shown significant noise suppression of electrical mains-noise features of up to 22 dB under the fundamental peak at 50 Hz, 3 dB at the first harmonic (100 Hz), and 21 dB at the second harmonic (150 Hz). This technique is software based, requires no additional hardware, and is easy to implement in an existing magnetometer.

Spatial and Frequency Specific Artifact Reduction in Optically Pumped Magnetometer Recordings

“…Our time-frequency analyses have revealed that FSSSC can remove multi-frequency artifacts [ 12 , 28 ]. Environmental noise appears in empty room recordings of the MEG data recorded without a human participant or a phantom.…”

“…Since the artifacts from the OPM sensors are generated by components within the OPMs (e.g., laser, heater, and vapor), these artifacts are called intrinsic artifacts [ 12 , 13 ]. Although some artifacts appear within restricted frequency bands (e.g., powerline noise at 50 Hz or 60 Hz) and spatial subspaces (e.g., out of the head) [ 12 , 13 ], many artifacts in OPM MEG may dynamically vary [ 13 ]. Consequently, it is essential to develop novel methods to remove artifacts in OPM MEG data.…”

Dynamic Response of a Light-Modulated Magnetometer to Time Dependent Field

“…This paper aims to provide a more general analysis of the behaviour of a Bell-and-Bloom magnetometer when it operates in the presence of a generic time dependent field that is parallel to the static (bias) one. The availability of a more accurate model is of relevance when the output of a magnetometer is used as an error-signal to implement feedback based field-stabilization systems [36][37][38][39][40], as well as when designing feed-forward ones [41] or when evaluating the effects of strong stray fields. The later is of particular relevance for systems operated in unshielded environment [9,42].…”

Ultra-low noise, bi-polar, programmable current sources

“…Precise current control is a vital tool in many scientific applications. Examples include: driving laser diodes 1 , characterisation of semiconductor devices 2 , high impedance tomography and spectroscopy 3 , and magnetic field manipulation [4][5][6] . Each of these applications differs in requirements, but all of them benefit from stability, low noise, and accuracy.…”