Three dimensional compensation spherical coils for compact atomic magnetometer

To avoid the broadening of Zeeman resonances of the vector atomic magnetometer working in an unshielded environment, a real-time magnetic compensation is necessary. Athree dimensional mini spherical compensation system is presented, which can be used for a compact 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 has been built and the measurement by traditional fluxgate magnetometer and the integration into the atomic system both demonstrate the validity of the design.