magnetometer

A magnetometer is a scientific instrument used to measure magnetic fields. It can determine the strength of a magnetic field and, in vector configurations, its direction. Magnetometers are employed in geophysics, navigation, space research, archaeology, and various laboratory applications to study natural and applied magnetic phenomena.

Magnetometers are generally classified as scalar or vector instruments. Scalar devices measure only the magnitude of the magnetic field, while vector magnetometers provide information about the three orthogonal components of the field. Many modern magnetometers are tri-axial, delivering full vector measurements. The sensing principles include fluxgate, Hall-effect, magnetoresistive, optically pumped magnetometers, and superconducting quantum interference devices (SQUIDs). Each technology offers different sensitivity, bandwidth, and operating conditions, from compact sensors for consumer electronics to highly sensitive instruments for scientific research.

Applications span a wide range. In geophysics, magnetometers map rock properties and monitor the Earth’s field for geomagnetic surveys and mineral exploration. In navigation, they serve as components of compasses in smartphones, aircraft, ships, and autonomous systems. In space science, magnetometers study planetary fields and solar wind. They are also used in archaeology to detect buried structures and in laboratory experiments to characterize magnetic materials and physical processes.

Performance characteristics include sensitivity, dynamic range, noise, temperature dependence, and susceptibility to magnetic interference. The Earth's field typically measures tens of microtesla, with smaller fluctuations detected in the nanotesla to microtesla range. Calibration, shielding, and software corrections are common to ensure accuracy in variable environments.