FPGA-Based Magnetic Field Camera for Dynamic Magnetic Field Mapping

This paper demonstrates the use of an FPGA and commercially available Hall effect magnetic field sensors to create a magnetic field camera offering high-speed capability for ac measurements. The achieved performance of the presented camera reaches 7 kHz of sampling rate over an array of 7 x 7 sensors, covering an area of 56 mm x 56 mm (31.36 cm²), synchronously sampled with a recording capability of up to 10 hours on X, Y and Z axis. The sensors exhibit a dynamic range of ± 266 mT, and a typical rms noise of 140 μT (peak-to-peak noise of 1 mT). Through its synchronous sampling capability and 7 kHz sampling rate, this camera fills a gap observed in the field of magnetic field cameras, in which mainly dc applications were addressed up to now. This opens the way to new metrological possibilities in several domains, ranging from industrial and physics applications to biomedical engineering.