Design of Self-oscillating Cesium Optically Pumped Magnetometer

This paper introduces the Zeeman effect of alkali metal atoms, the principle of optically pumping and magnetic resonance. Based on the physics rationale of an optically pumped magnetometer, the mechanical and electrical structures of the OPM sensor are designed. Aimed at non-magnetic heating, a temperature control system of cesium vapor cell is designed with a flexible printed circuit as the heating element, and the temperature control accuracy reached 0.6 ℃. The circuit parameters of the differentiator are optimized, and a −90° phase shifter is designed to form the self-oscillating feedback loop with a phase shift bandwidth of more than 1 MHz. The experimental system of cesium optically pumped magnetometer is built, and the resonance signal with a high signal-to-noise ratio indicates that the intensity of the geomagnetic field in the laboratory environment is 34027.5 nT. The relationship between the OPM signal amplitude and the temperature of the cesium vapor cell is investigated. The results show that the optimal temperature of the cesium cell is 54.4 ℃. The sensitivity of the magnetometer prototype calculated according to the power spectrum reaches $$10\,\mathrm{ pT}/\sqrt{\mathrm{Hz}}$$ .