A Pea-Sized Magnetometer

A pea-sized magnetometer can do the job of much bigger units, and measure magnetic fields with a sensitivity of 50 pico-tesla. Researchers at NIST exploit the fact that rubidium atoms possess quantum levels whose energies will depend on the ambient magnetic field. By encapsulating a tiny portion of atoms in a cell and making precision measurements of laser light traveling through the atoms, a field reading can be made. All of this is packaged in only about 12 cubic millimeters. Furthermore, the device can be manufactured in large batches through lithographic means. For geophysical applications, such as for detecting underwater or underground iron objects such as pipelines, tanks, and shipwrecks, the device’s tiny power consumption, compact size, and low price should move it ahead of several existing magnetometer designs with a few more years of development work. (Schwindt et al., Applied Physics Letters, 27 December 2004; contact Peter Schwindt, schwindt@boulder.nist.gov, 303-497-7969; lab website at www.boulder.nist.gov/timefreq/ofm/smallclock/CSAM.htm )