Dipole Localization Using An Integrated Radio Frequency Atomic Magnetometer

Abstract

Optically-pumped atomic magnetometers have previously been used in arrays to reject interference from far away sources and enable the sensitive detection of local sources of radio frequency (RF) signals, useful, for instance, in the detection of low field NMR signals in an unshielded environment. We now demonstrate a complementary scheme in which four magnetometer measurements are used to locate in three dimensions a nearby radio frequency source. The methodology relies on the measurement of a radio frequency vector at two different positions and modeling the source as a magnetic dipole of known orientation. In contrast to coil detection, magnetometers have the advantage of measuring signals in a 2D plane, and do not inductively couple to their environment or each other, making them a strong candidate for localization of hidden RF sources. For this demonstration, we use only a single RF magnetometer to make four measurements of a synchronous and oriented dipole source, but it is to be expected that this could be replaced by four magnetometers working simultaneously. In addition, this work is greatly aided by the introduction of a fully integrated magnetometer, in which all optics, including lasers, are safely enclosed into a compact head with flexible wired connections. The portable, as well as safe, nature of the sensor make it quite valuable for in the field work.