A Nuclear Magnetic Resonance (NMR) Gyro with Optical Magnetometer Detection

A nuclear magnetic resonance (NMR) gyroscope senses rotation as a shift in the Larmor frequency of nuclear magnetic moments as they precess about an applied field. A sensitive optically pumped magnetometer has been developed which can sense the weak magnetic fields associated with the nuclear moments and thus allow the detection and determination of the Larmor precession frequency. The magnetometer operates on the principle that the absorption of optical pumping light by rubidium atoms is a function of the direction of the rubidium magnetic moment relative to that of the light beam and that the direction of the rubidium magnetic moment is itself a function of the magnetic field. Thus a magnetic field modulated at a nuclear Larmor frequency can cause modulations in the transmitted optical pumping light at this same frequency. A breadboard NMR gyro utilizing this magnetometer method has recently been tested. It is characterized by a high signal-to-noise ratio and a low random bias drift.