A compact atomic co-magnetometer for moving MEGs recording

Due to its very high sensitivity, atomic magnetometer could be utilized for brain magnetic field measurement. Moreover, the room temperature magnetometer could be integrated to a helmet and could be utilized for moving MEGs measurement. The moving MEGs recording could study several brain's functions such as space navigation. However, the moving related fluctuation background magnetic field could cause very large background magnetic field noise. Here we will describe an atomic co-magnetometer which could be potential for the moving MEGs recording. The nuclear spins utilized in the atomic co-magnetometer could self-compensate the background magnetic field noise while retain the co-magnetometer's sensitivity to the brain magnetic field whose frequencies are higher than 5Hz. Here we will show our design of the compact atomic co-magnetometer which could be mounted to the head. The single beam absorption design could greatly reduce the volume of the sensor head. The co-magnetometer also requires three direction magnetic fields for the operation. We chose to use the bi-planar coil system for the design and the magnetic field gradient produces by the coils are studied. The bi-planar coil system could confine the electricity of the coils in only two paralleled plane and produces three dimensions of magnetic field. Thus, it is quite suitable for the compact design of the atomic co-magnetometer. A model was developed to measure the gradients of the coils and an optimized bi-planar coil system was developed to improve the uniformity of the magnetic field.