Magnetic Subsurface Imaging Systems in a Smartphone Based on the Built-In Magnetometer

We present a magnetic subsurface imaging system on a smart-phone that employs the built-in magnetometer. The smart-phone's sensor measures magnetic field strength at sparse locations on a user-defined grid of the surveyed area. Based on the collected data, magnetic field distribution of the entire area is then reconstructed by using an interpolation algorithm, which yields field values in all of three-axial directions. Since the field shows the influence of the buried objects within the surveyed area to the background magnetic fields, the shape and size of the objects can be derived from the image representing the field. An implementation of the system as an application software on Android smart-phone, which consists of data measurement and reconstruction subsystems, is also described. We demonstrate the capability of the proposed system by performing subsurface imaging of small hidden objects in a laboratory test-range.