US 11,965,943 B2
Bias field control of total-field optically pumped magnetometers (OPMs) for improved detection
Richard B. Choroszucha, Tucson, AZ (US); George G. Descamps, Sahuarita, AZ (US); and James T. Landon, Marana, AZ (US)
Assigned to Raytheon Company, Tewksbury, MA (US)
Filed by Raytheon Company, Tewksbury, MA (US)
Filed on Apr. 15, 2022, as Appl. No. 17/722,017.
Prior Publication US 2023/0333178 A1, Oct. 19, 2023
Int. Cl. G01R 33/26 (2006.01); G01R 33/032 (2006.01)
CPC G01R 33/26 (2013.01) [G01R 33/032 (2013.01)] 19 Claims
OG exemplary drawing
 
18. A magnetometer, comprising:
a platform;
a single total-field optically pumped magnetometer (OPM) mounted on the platform, said OPM having a detection zone along a detection axis and a dead zone orthogonal to the detection axis, a boundary separating the detection and dead zones defined by an angle theta θ1 from a Z-axis in an XYZ coordinate space;
a single electromagnetic (EM) coil positioned proximate the OPM and oriented such that when energized the first EM coil produces a bias magnetic field Bbias that is substantially parallel to the detection axis in a local volume around the OPM to move an observable field Bmeas from the dead zone into the detection zone;
current control logic responsive to calibration parameters including soft iron M and hard iron C that characterize the platform and a definition of the dead zone to compute a minimum required bias magnetic field Bbias to move Bmeas into the detection zone, wherein Bbias is updated at a rate sufficient to maintain Bmeas in the detection zone while not interfering with the operation of the OPM; and
current control circuit responsive to the computed bias to generate a current to energize the first EM coil.