Opto-mechanical magnetometer based on laser speckle correlation

Abstract Magnetic field sensing plays vital role in vast range of areas such as navigation, military, and biomedical sciences. In recent times, optical sensors have made great advances, resulting in the development of magnetic field sensors based on optical principles due to their non-susceptibility to electromagnetic interference. Here, a simple and inexpensive approach for sensing magnetic field, that converts the magnetic field into a mechanical translation (of the sensing element) and then change into optical signals is presented. These optical signals are speckle patterns generated using a laser beam reflected off an optically rough metal cantilever which is exposed to the magnetic field. Magnetic field is quantified by measuring the changes in the speckle pattern using the intensity correlation technique. The approach can measure the static and time varying magnetic fields. The proposed system has a resolution of 2.2 μ T and can measure magnetic fields with less than a 2% error.