Electromagnetic induction imaging with a SERF atomic magnetometer

We construct an electromagnetic induction imaging (EMI) system based on a SERF (Spin-Exchange-Relaxation-Free) atomic magnetometer. The homemade SERF magnetometer relies on the optical magnetic resonance absorption to obtain the magnitude of the secondary magnetic fields of object, and only one laser beam is used for both pumping and detection. Besides, by using sub-harmonics in beating signal, the scheme of the imaging system is simplified with fast Fourier transform (FFT) instead of the lock-in amplifier. Overall, our scheme has a simple structure, which is very conducive to miniaturization and portability. In our experiment, the frequency regions of RF and the corresponding magnitude of the generational secondary magnetic field are both investigated to find that the optimal operation RF frequency is about kHz, which lead to a deeper object’s penetration depth. Furthermore, due to the high sensitivity of SERF atomic magnetometer, we can have a clear imaging based solely on the magnitude of the secondary magnetic fields without the information of its phase.