A real time high sensitivity high spatial resolution quantum well hall effect magnetovision camera

Abstract A real time magnetovision camera with a refresh rate of 600 frames per second (fps) was developed based on small size, high sensitivity Quantum Well Hall Effect (QWHE) sensors. This handheld system consists of a 16 × 16 QWHE sensor array covering an 80 mm × 80 mm area. This system has a spatial resolution of 5.08 pixels per inch (ppi). By using a superheterodyne technique to reduce the impact of (1/f) noise, magnetic fields down to 2 μT can be detected for both direct and alternating magnetic field operations. Experimental results of five case studies demonstrate that magnetic flux leakage (MFL) and magnetovision imaging in DC and AC magnetic field resulting from defects and shape, can be successfully measured. The major applications of this new system are: (1) in MFL testing equipment with permanent magnets or electromagnets, (2) to obtain 2D graphical imaging similar to magnetic particle inspection (MPI) without its inherent drawbacks, (3) for examination of non-ferromagnetic materials such as aluminium, copper, and stainless steels for deep defects below the surface using low frequency alternating magnetic fields, and (4) for material identification, which has a considerable potential in several applications such as in security, product protection, bio-imaging, and medical.