Detection of Optical–Magnetic Axis Inconsistency in Multifunctional Magnetometers

Multifunctional magnetometers enable high-precision observations of the geomagnetic direction and total magnetic field, which have broad applications in geoscience research and space weather forecasting. However, inconsistencies still occur between the optical and magnetic axes of classic multifunctional magnetometers, and few studies have investigated their direct detection. To address this issue, we propose a novel method for the detection of the optical-magnetic axis inconsistency. The magnetic azimuths for the magnetic axis and the optical axis of the multifunctional magnetometer are determined through the bias field loading and fluxgate theodolite, thereby allowing direct detection of the inconsistency. The proposed method is also modeled to quantify the detection errors introduced by the total-field sensor and the observation operation. In addition, we develop a dedicated experimental platform and conduct comparative tests at a geomagnetic observatory to validate the practicality and performance of the method. The experimental results show that the proposed method can significantly reduce the deviation of the declination curve measured by the multifunctional magnetometer relative to the curve measured by the fluxgate theodolite from 3959′′ to 19′′, achieving a 99.5% reduction rate.