Cylindrical Vector Beam for Vector Magnetic Field Sensing Based on Magnetic Fluid

Based on the unique polarization characteristic of the cylindrical vector beam, a new-type vector magnetic field sensing technique is proposed. As the cylindrical vector beam passes through a magnetic fluid film, a polarization analyzer is used to detect the polarization state change of the output light after passing through a slit. Based on the birefringence effect, the direction of the magnetic field can be resolved by the direction of the maximum ellipticity, while the magnetic field strength can be obtained by the change of the maximum ellipticity. Both of the magnetic field strength and direction in the X-Y plane could be measured simultaneously. The experimental results show that the direction error is less than 2°, the strength error is less than 10 Gs, and the sensitivity of the strength of magnetic field is 0.12 °/Gs. Therefore, the proposed technique would be promising for two-dimensional magnetic field detection and safety detection, such as high-voltage discharge magnetic field detection.