Magnetic Source Imaging Using a Pulsed Optically Pumped Magnetometer Array

Abstract

We have developed a pulsed optically pumped magnetometer (OPM) array for detecting magnetic field maps originated from an arbitrary current distribution. The presented magnetic source imaging (MSI) system features 24 OPM channels, has a data rate of 500 S/s, a sensitivity of 0.8 pT / Hz, and a dynamic range of 72 dB. We have employed our pulsed-OPM MSI system for measuring the magnetic field map of a test coil structure. The coils are moved across the array in an indexed fashion to measure the magnetic field over an area larger than the array. The captured magnetic field maps show excellent agreement with the simulation results. Assuming a 2D current distribution, we have solved the inverse problem, using the measured magnetic field maps, and the reconstructed current distribution image is compared to that of the simulation.

In-Situ Measurement of Electrical-Heating-Induced Magnetic Field for an Atomic Magnetometer

“…, and B h_DC z ) were calculated from the data in Table 1 using Equation (6). We can see that the measurement uncertainty of B h_DC was less than 0.2 nT along the x axis, 1.0 nT along the y axis, and 0.4 nT along the z axis at all cell temperatures.…”

“…Next, the heating mode was switched to the DC heating mode. After several minutes when the cell temperature was stable, B c_DC was measured using the same method, and B h_DC was calculated using Equation (6). During this process, the excitation current of the Pt1000 was set at a constant value of 100 µA.…”

“…Atomic magnetometers have been used in a wide range of applications to detect weak magnetic fields, such as magnetoencephalography (MEG) [1][2][3], magnetocardiography (MCG) [4][5][6], and the search for new physics [7,8]. Currently, the most sensitive atomic magnetometer is the spin-exchange relaxation-free (SERF) magnetometer [9], which was first presented by the Romalis group at Princeton University [10].…”

Ultrasensitive Magnetic Field Sensors for Biomedical Applications

“…Novel advances in the fields of microfabrication and optical interrogation have led to significant progress in optically pumped atomic magnetometers [121][122][123][124]. The operating mechanisms of such sensors are (i) coherent population trapping [125], (ii) non-linear magneto-optical rotation [126], and (iii) spin-exchange relaxation-free [34] regimes.…”

Optical Rotation Detection for Atomic Spin Precession Using a Superluminescent Diode

“…As a result, the atomic magnetometer has a compact structure, providing a new solution with better spatial resolutions for magnetoencephalography [5] and magnetocardiography systems [6]. On the other hand, the operation of atomic magnetometers is much simpler than that of SQUID magnetometers, allowing free and natural movement for patients during the scanning process [7][8][9]. Moreover, the atomic magnetometer has a bandwidth ranging from static to hundreds of kilohertz [10], which can be applied to more fields such as detection of microparticle in size of micrometers [11] and magnetic particle imaging (MPI) [12].…”