Magnetic sensors has great application value in biomedical

resource exploration

aeronautics and astronautics. Weak magnetic sensors based on atomic spin effect has been the most sensitive instruments in magnetic field measurement. These sensors usually employ the sheme of RF modulation or off-resonant laser light detection. The former will give rise to magnetometer linewidth broadening and the latter will make it difficult to lock laser freqency. In order to solve above problem

a project based on laser intensity modulation and circular dichroism detection is proposed. The operation principle and system configuration are described in detail

and the properties of atomic weak magnetic sensor is tested. Experimental results show that the magnetic resonant linewidth is 22 Hz

with 30 min continuous measurement of constant magnetic field

its peak to peak value is less than 9 pT and sensitivity achieves 0. 12 pT / Hz1 /2.