Executive Summary : | Optically pumped atomic magnetometers are used for the sensitive detection of magnetic fields in various research fields, including fundamental science, biomagnetism, and geophysics. These magnetometers measure the Larmor precession of spin-polarized atoms in the presence of an unknown magnetic field. Techniques have been employed to improve sensitivity and dynamic range of these magnetometers. Synchronous optical pumping of atoms with modulated light allows for high precision in measuring geomagnetic fields. Traditional atomic magnetometers use steady-state magnetic resonances, which require an initial estimate of the unknown magnetic field before taking a measurement. However, an atomic magnetometer based on the oscillatory free-induction decay (FID) of atomic spins does not require any prior estimate of the unknown magnetic field and can be operated in both single-pulse and synchronous optical pumping configurations. The proposed FID magnetometer will be developed using two amplitude-modulated laser beams resonant from hyperfine ground states Fg=2 and Fg=1 to a common hyperfine excited state Fe=1 of ⁸⁷Rb D₁ line. The performance of the magnetometer will be assessed under different operating conditions by measuring laboratory magnetic fields. Compactness and portability are important design goals for the proposed magnetometer, as atomic magnetometers can be constructed in a very small size. |