Three dimensional compensation spherical coils for compact atomic magnetometers

To avoid the broadening of Zeeman resonances of the vector atomic magnetometer working in an unshielded environment, the rapid and accurate magnetic compensation is necessary. A three dimensional mini spherical compensating system is presented, which can be used together with a chip-scale atomic magnetometer to realize an ultra-high precision field measurement. Based on the field gradient method, parameters are optimized to obtain a uniformity of 10^-3 over the region of one half radius with a good tolerance on dimensional variations. A prototype applied in the single laser beam scheme has been built and the experimental results demonstrate the validity of the design.