Compact atomic magnetometer and gyroscope based on a diverging laser beam

A magnetic field sensing device, comprising:

• a magnetic shield to suppress external magnetic fields;
• a cell adapted for containing alkali atoms at a vapor pressure so that said alkali atoms can become polarized;
• a light source generating light field comprised of more than one propagation vector, wherein said light source is arranged to pass said light field through said cell;
• a light source adapted to circularly polarize light;
• at least one photodetector adapted to measure a magnetic field strength based on a reaction of said light with said alkali atoms after said light field is passed through said cell, wherein said at least one photodetector comprises photodiodes positioned on a base plate;
• and
• wherein said apparatus is adapted in a gyroscope implementation that comprises an additional “noble” gas.

A method of detecting magnetic fields comprising the steps of:

• emitting light from a light source;
• passing said light through at least one wave plate including optics adapted to circularly polarize light from said light source, attenuate the light and change its spatial mode;
• passing said light through a cell containing an alkali species and at least one noble gas or equivalent;
• generating an oscillating magnetic filed at a Larmor frequency of noble gas atoms in a direction perpendicular to said magnetic field with at least one of a plurality of coils;
• generating an oscillating magnetic field at said Larmor frequency of the alkali atoms with a second set of said coils;
• causing an atomic polarization to precess at a drive frequency about a magnetic field;
• detecting a transverse component of said atomic polarization by monitoring an absorption of the edges of a diverging light beam using a plurality of photodetectors;
• and
• determining the magnitude of the precessing transverse atomic polarization by subtracting signals coming from opposite sides of said light beam.

An apparatus for sensing magnetic fields, wherein the apparatus comprises:

• a cell adapted for containing alkali atoms at a their vapor pressure so that said alkali atoms can become polarized;
• a light source adapted to generate a diverging beam of light arranged so that said diverging beam of light is passed through said cell wherein said light source is adapted to produce circularly polarize light;
• and
• at least one photodetector adapted to measure magnetic field strength based on a reaction of part of said beam of light with said alkali atoms after said light field is passed through said cell.