Abstract: Systems and methods using a magneto-optical defect center material magnetic sensor system that uses fluorescence intensity to distinguish the ms=±1 states, and to measure the magnetic field based on the energy difference between the ms=+1 state and the ms=?1 state, as manifested by the RF frequencies corresponding to each state in some embodiments. The system may include an optical excitation source, which directs optical excitation to the material. The system may further include an RF excitation source, which provides RF radiation to the material. Light from the material may be directed through a light pipe to an optical detector. Light from the material may be directed through an optical filter to an optical detector.