Optical-Magnetometry-Based Current Source

We present a current-monitoring system based on optical magnetometry, which is able to discriminate true current variations from environmental effects at room temperature. The consists of dedicated thermally stable magnetic-field-confining coil and an array four optically pumped magnetometers arranged in two-dimensional gradiometer configuration. These monitor magnetic field inside the coil, correlate with driving coil. uses digital signal-processing unit extract record real time values measured by magnetometers, allows real-time monitoring current. system, made out printed circuit boards, can easily be changed adapt current-to-field conversion. Thus, we expand applicability this wide range currents. By using actively feedback control source, stabilize 20 mA level better than $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ for integration 70 min.