Abstract: A method is provided for sensing a magnetic field in a magnetic gradiometer of the kind in which pump light and light constituting an optical carrier traverse first and second atomic vapor cells that contain host atoms and that are separated from each other by a known distance. According to such method, the host atoms are prepared in a coherent superposition of two quantum states that differ in energy by an amount that is sensitive to an ambient magnetic field. Modulation of the optical carrier in the respective cells gives rise to sidebands that interfere to generate a beat frequency indicative of the magnetic field gradient. The host atoms are prepared at least in a mode that allows measurement of ambient magnetic field components perpendicular to the axis of the pump light. In such mode, the host atoms are spin-polarized by pump light while subjected to a controlled magnetic field directed parallel to the pump beam, and then the controlled magnetic field is adiabatically extinguished.

Abstract: A wearable and customizable multi-shell MEG helmet comprising an inner shell and outer shell, wherein the inner shell interior surface is customized to conform to the patient's head shape so that the helmet assembly moves in unison with the patient's head movement and sensor locations are controlled and remain fixed relative to the brain. This invention improves data quality and user comfort since head movements may be permitted and their effects on data integrity is minimized. The outer shell is generic and may fit over any customized inner shell. The outer shell holds a group of sensors, which may be, but not limited to, optically pumped magnetometers. This generic outer shell may mate with the inner shell, allowing sensors to be easily pushed into the inner shell to be in closer proximity to the patient's head.

Abstract: This disclosure relates to the field of zero-field paramagnetic resonance magnetometer (ZF-PRM). A sensitive ZF-PRM capable of measuring magnetic field in three orthogonal directions simultaneously and method of measuring magnetic field in three orthogonal directions is described. The ZF-PRM provides three independent output signals proportional to the three orthogonal vector components of the magnetic field using a single vapor cell, thus reducing complexity and cost of the magnetometer. Because all three magnetic components are measured at substantially the same location at the same time, the accuracy of data is greatly increased.

Abstract: A two-stage laser stabilization method is described to simultaneously servo two coupled laser parameters that control the wavelength of a laser, such as the laser injection current and the laser temperature, in order to simultaneously stabilize the laser frequency and output power. Two error signals are generated by passing the laser light through a frequency discriminator, such as an atomic resonance, to generate two control loops for the two coupled laser parameters. A primary control loop servos the faster laser parameter, such as the laser injection current, by direct use of the error signal. A secondary slower control loop ensures that this said error signal will remain at zero, by controlling the second laser parameter, such as the laser temperature.

Abstract: A calibration system and method is described to continuously measure and adjust several parameters of a magnetic imaging array. One or more non-target magnetic field source(s) are used to generate a well-defined and distinguishable spatial magnetic field distribution. The magnetic imaging array is used to measure the strength of the non-target magnetic fields and the information is used to calibrate several parameters of the array, such as, but not limited to, effective magnetometer positions and orientations, gains and their frequency dependence, bandwidth, and linearity. The calibration can happen continuously or periodically, while the imaging array is operating to create magnetic field images, if the modulation frequencies for calibration are outside the frequency window of interest.

Abstract: A system and method to measure a magnetic gradient field with an optically-pumped magnetometer is described. Atoms are spin polarized at two locations. Larmor frequencies are, induced and the spin frequency is detected. The frequencies are proportional to the total magnetic field at the locations of the atoms. The magnetic field gradient is extracted from the beat frequency of the two Larmor frequencies.

Abstract: A two-stage laser stabilization method is described to simultaneously servo two coupled laser parameters that control the wavelength of a laser, such as the laser injection current and the laser temperature, in order to simultaneously stabilize the laser frequency and output power. Two error signals are generated by passing the laser light through a frequency discriminator, such as an atomic resonance, to generate two control loops for the two coupled laser parameters. A primary control loop servos the faster laser parameter, such as the laser injection current, by direct use of the error signal. A secondary slower control loop ensures that this said error signal will remain at zero, by controlling the second laser parameter, such as the laser temperature.

Abstract: A mutually calibrated magnetic imaging array system is described. The system includes a non-target magnetic source rigidly attached to a magnetometer, and an attached control unit to measure and adjust several parameters of a magnetic imaging array. A non-target magnetic field source is used to generate a well-defined and distinguishable spatial magnetic field distribution. The source is rigidly attached directly to a magnetometer, while the relative positions of the magnetometers are unknown. The magnetic imaging array is used to measure the strength of the non-target source magnetic fields and the information is used to calibrate several parameters of the array, such as, but not limited to, effective magnetometer positions and orientations with respect to each other and cross-talk between the magnetometers. The system, and method described herein eliminates the need for a separate calibration phantom.

Abstract: A zero-field paramagnetic resonance magnetometer (ZF-PRM) system and method for quickly and efficiently finding and optimizing the zero-field (ZF) resonance is described. In this system and method a magnetic coil is used to apply a magnetic bias field in the direction of the pump beam to artificially broaden the width and maximize the strength of the ZF resonance. By making the ZF resonance easy to detect, the ZF resonance may be found quickly found without the use of additional components and complex algorithms. Once the ZF resonance is found, a compensating magnetic field can be applied to null the magnetic field in the vicinity of the vapor cell in the ZF-PRM, thereby initializing it for operation.

Abstract: A zero-field paramagnetic resonance magnetometer (ZF-PRM) system and method for quickly and efficiently finding and optimizing the zero-field (ZF) resonance is described. In this system and method a magnetic coil is used to apply a magnetic bias field in the direction of the pump beam to artificially broaden the width and maximize the strength of the ZF resonance. By making the ZF resonance easy to detect, the ZF resonance may be found quickly found without the use of additional components and complex algorithms. Once the ZF resonance is found, a compensating magnetic field can be applied to null the magnetic field in the vicinity of the vapor cell in the ZF-PRM, thereby initializing it for operation.

Abstract: A zero-field paramagnetic resonance magnetometer (ZF-PRM) system and method for quickly and efficiently finding and optimizing the zero-field (ZF) resonance is described. In this system and method a magnetic coil is used to apply a magnetic bias field in the direction of the pump beam to artificially broaden the width and maximize the strength of the ZF resonance. By making the ZF resonance easy to detect, the ZF resonance may be found quickly found without the use of additional components and complex algorithms. Once the ZF resonance is found, a compensating magnetic field can be applied to null the magnetic field in the vicinity of the vapor cell in the ZF-PRM, thereby initializing it for operation.