An Optically Pumped Magnetometer with Omnidirectional Magnetic Field Sensitivity

Area of Science:

• Geophysics
• Atomic Physics
• Sensor Technology

Background:

• Optically pumped magnetometers (OPMs) are crucial for mobile applications like geomagnetic surveying.
• Dead zones and heading errors significantly limit the performance of conventional OPMs.
• These limitations arise from sensor orientation-dependent signal amplitude drops and magnetic field measurement variations.

Purpose of the Study:

• To present a novel concept for an omnidirectional magnetometer.
• To overcome dead zones and heading errors in OPMs for enhanced mobile surveying.
• To achieve nearly isotropic magnetic-field sensitivity.

Main Methods:

• Utilized a dual-cesium vapor cell configuration.
• Employed circularly-polarized, amplitude-modulated laser light split into perpendicular beams.
• Experimentally investigated the sensor in a magnetically shielded environment with adjustable laser beam and magnetic field orientations.

Main Results:

• Demonstrated a dead-zone-free magnetometer.
• Achieved nearly isotropic magnetic-field sensitivity.
• Observed heading errors due to light shifts and nonlinear Zeeman effect in the current configuration.

Conclusions:

• The proposed omnidirectional magnetometer concept effectively eliminates dead zones.
• A straightforward approach to suppress systematic effects like light shifts and nonlinear Zeeman effect is introduced for advanced sensor realization.
• This technology promises improved accuracy and reliability in geomagnetic surveying and other mobile magnetic field measurement applications.