Calibration and Localization of Optically Pumped Magnetometers Using Electromagnetic Coils

10Citations
Citations of this article
10Readers
Mendeley users who have this article in their library.

Abstract

In this paper, we propose a method to estimate the position, orientation, and gain of a magnetic field sensor using a set of (large) electromagnetic coils. We apply the method for calibrating an array of optically pumped magnetometers (OPMs) for magnetoencephalography (MEG). We first measure the magnetic fields of the coils at multiple known positions using a well‐calibrated triaxial magnetometer, and model these discreetly sampled fields using vector spherical harmonics (VSH) functions. We then localize and calibrate an OPM by minimizing the sum of squared errors between the model signals and the OPM responses to the coil fields. We show that by using homogeneous and first‐order gradient fields, the OPM sensor parameters (gain, position, and orientation) can be obtained from a set of linear equations with pseudo‐inverses of two matrices. The currents that should be applied to the coils for approximating these low‐order field components can be determined based on the VSH models. Computationally simple initial estimates of the OPM sensor parameters follow. As a first test of the method, we placed a fluxgate magnetometer at multiple positions and estimated the RMS position, orientation, and gain errors of the method to be 1.0 mm, 0.2°, and 0.8%, respectively. Lastly, we calibrated a 48‐channel OPM array. The accuracy of the OPM calibration was tested by using the OPM array to localize magnetic dipoles in a phantom, which resulted in an average dipole position error of 3.3 mm. The results demonstrate the feasibility of using electromagnetic coils to calibrate and localize OPMs for MEG.

Cite

CITATION STYLE

APA

Iivanainen, J., Borna, A., Zetter, R., Carter, T. R., Stephen, J. M., McKay, J., … Schwindt, P. D. D. (2022). Calibration and Localization of Optically Pumped Magnetometers Using Electromagnetic Coils. Sensors, 22(8). https://doi.org/10.3390/s22083059

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free