Weak Magnetic Field Measurement by Using All-optical Potassium Atomic Spin Magnetometer

摘要

The SERF atomic spin magnetometer, which can be used to measure the residual weak magnetic field in the magnetic shield due to its ultrahigh sensitivity, is elaborated in this paper. The method of using the SERF atomic spin magnetometer to measure the residual weak magnetic field in the magnetic shield was presented. The compensating coils, which were placed inside the magnetic shield, produced the uniform magnetic fields along the x, y and z directions, and they were reverse direction with the residual weak magnetic fields; via the cross modulation method, the residual weak magnetic fields could be counteracted. At this time, the magnetic fields producing by the compensating coils were equal to the residual weak magnetic fields in the magnetic shield. The experimental results showed that the residual weak magnetic fields were approximate 0.5 nT, 1.0 nT and 7.0 nT along the x, y and z directions, respectively; and the maximum measurement errors were approximate 0.0169, 0.0377, and 0.5071 along the x, y and z directions, respectively. Finally, the reasons of measurement error were analyzed.