Abstract: This paper describes a laser-pumped cesium-helium magnetometer(CHM).By using the single mode diode laser to get higher polarization efficiency,the stronger magnetic-resonance signal compared with the conventional lamp-pumped scheme is got.By measuring the noises from light,background field,pulse discharge and signal amplifier circuits,we find that the light power fluctuation is the dominant noise.We study the relation between signal-to-noise ratio and the light intensity,and then find out an optimal light intensity.Under the best experimental parameters,the peak-to-peak noise can superior to 0.02 nT.The results of the experiment show that by improving the stability of the light power,the laser pumped CHM has great potential to achieve a higher accuracy than proton magnetometers,can be used as a new generation of main measuring equipment for constant weak magnetic field measurement.

Key words: Cs-He magnetometer, Spin-exchange collision, Chemi-ionization, Laser pumping