A DSP-based closed loop serf atomic magnetometer

Spin-exchange relaxation-free (SERF) atomic magnetometers offer potential in ultra-sensitivity, miniaturization and low-cost. However, further improvements in bandwidth and dynamic range are required to detect high-frequency biomagnetic signals and overcome uncertain environmental magnetic field fluctuation. In this work, we proposed a fully integrated closed-loop SERF atomic magnetometer, which is implemented on an embedded chip for compactness and low-cost. Firstly, we theoretically analysis the signal transfer model in the single-beam SERF magnetometers, and implemented the core lock in amplifier (LIA) and PID module on SigmaDSP chip. Then, we experimentally investigated the dependence of the amplitude–frequency response of the lock-in amplifier on the filter order and cut-off frequency. and optimized the PID parameters to broaden the magnetometer bandwidth. Experimental results show that the dynamic range of the closed-loop magnetometer is enhanced from 5 to 50 nT, limited by coil dimensions. The closed-loop bandwidth is extended from 100 to 300 Hz, while maintaining a sensitivity better than 20 fT/Hz1/2. This study presents a lightweight upgrade strategy that enhances the magnetometer’s robustness to fluctuating magnetic fields, and improves its capability for high-frequency magnetic field detection.