Detection and imaging of magnetic field in the low frequency regime using a ferromagnetic thin film coated with a thermo-fluorescent layer

A novel and original method of low-frequency magnetic field imaging is presented, that uses a magnetic thin film coated with fluorescent dye. Due to high permeability and consequent hysteresis losses, the film is heated by the field. As the fluorescence of the coated material is temperature-dependent, magnetic field mapping can be obtained in a short time and on a large surface by recording images with an S-CMOS camera. This principle had been previously presented in the microwave regime, for both electric and magnetic fields imaging; here, we propose first results in the low-frequency regime (kilohertz frequency range).