Sensor array system for real time visualization of magnetostatic fields and imaging of ferrous objects

This paper describes a solid-state based multi-element sensor array system capable of real-time imaging of DC magnetic fields and ferrous objects. The final laboratory system comprises 1155 solid state magneto-inductive sensors arrange in a 2D array matrix of 35 × 33 files an columns, equally spaced in order to cover an approximate area of 320 by 300 mm. The sensor array is located within a large current-carrying coil, which may be exited when required to produce a steady magnetic field. This coil is used when required to imaging metallic objects. Data from the sensors array are sampled sequentially by several DSP controlling units and finally streamed to a host computer using USB 2.0 interface; images are generated and displayed at a rate of about 30 frames per minute. Extensive numerical modeling of field distribution patterns using boundary element method has complemented the development of the system. Both numerical simulations and experimental results are shown and discussed. The system was originally intended for deployment in the non-destructive evaluation (NDE) of reinforced concrete, being capable of imaging embedded rebar of different diameters and configurations up to a depth of 100 mm. Nevertheless, the system is also capable of producing real-time images of the magnetic field distribution emitted by either permanent magnets or geometries carrying current.