An Novel Atomic Scalar Magnetometer Using Laser

Abstract

The measurement precision of commercial atom scalar magnetometer is relatively backward compared with that of quantum magnetometer. However, the application of quantum magnetometers such as SERF requires more stringent environmental background requirements, which is not suitable for magnetic field measurement in the geomagnetic environment. The purpose of this paper is to design a 4He atom scalar magnetometer using ECDL laser. Compared with the conventional atomic scalar magnetometer, this magnetometer has higher measuring precision and can work normally in the geomagnetic environment. In order to achieve the above goals, the sensitivity formula of the atomic scalar magnetometer is first deduced and calculated, and the key physical factors that directly affect the sensitivity are the optical pumping rate, transverse relaxation rate, and longitudinal relaxation rate. Then, the light source and 4He cell are determined as key components which affect sensitivity. On this basis, the optical path of the 4He atomic scalar magnetometer using laser is designed in this paper. The light path ensures the stability of the laser wavelength of 1083.207nm by the saturation absorption spectrum method, and it ensures the circularly polarized light enters the 4He cell through the combination of various optical components. This paper also studies the electric excitation technology of the 4He cell. And, combined with simulation experiments, the High-Frequency discharge excitation circuit with high energy transfer efficiency and corresponding matching network are determined. Through the optical wavelength meter, it can be determined that the optical path designed in this paper can guarantee the wavelength stability of 1083.207nm for a long time. By analyzing the detection signals of PD, the circularly polarized light enters the 4He cell in the light circuit designed in this paper has a higher degree of polarization. The High-Frequency discharge excitation circuit designed in this paper can light up the cell smoothly, and the input power when the circuit works stably is about 6W. Finally, the static sensitivity of the magnetometer is 5pT/Hz1/2. The 4He atom scalar magnetometer using ECDL laser designed in this paper has high static sensitivity, which basically meets the design requirements, and the instrument can be used normally in the geomagnetic environment. However, the instrument still has a lot of room for improvement, including optical path and cell performance optimization, and we will continue to study in this direction.