One embodiment is a magnetic field measurement system that includes at least one magnetometer having a vapor cell, a light source to direct light through the vapor cell, and a detector to receive light directed through the vapor cell; at least one magnetic field generator disposed adjacent the vapor cell; and a feedback circuit coupled to the at least one magnetic field generator and the detector of the at least one magnetometer. The feedback circuit includes at least one feedback loop that includes a first low pass filter with a first cutoff frequency. The feedback circuit is configured to compensate for magnetic field variations having a frequency lower than the first cutoff frequency. The first low pass filter rejects magnetic field variations having a frequency higher than the first cutoff frequency and provides the rejected magnetic field variations for measurement as an output of the feedback circuit.

A driver support system of a vehicle that includes a neuroimaging sensor and a positioning sensor, the neuroimaging sensor detects neurological signals of an occupant and the positioning sensor detects a position of the occupant. The neuroimaging sensor is configured to be positioned within the vehicle distally from the occupant. The system further includes a processor and non-transitory computer-readable medium storing computer-readable instructions executed by the processor to generate a brainwave map based on the neurological signals, calibrate the brainwave map based on the position of the occupant, and determine a mental state of the occupant based on the calibrated-brainwave map. The processor further actuates vehicle support control in response to determining the mental state of the occupant.

Medical diagnostic devices and related methods of use are described in which one or multiple coils in a sensor, each coil connected with an RLC circuit and frequency counter, are held against a patient's head at predetermined cranial locations. Frequencies of the RLC circuit are measured and compared against those taken from known, control heads, to determine whether there is a medical problem and what type of problem. In some instances, too high of frequencies can reveal pooled blood in the head, a sign of hemorrhagic stroke, while too low of frequencies imply lack of blood supply, a sign of ischemic stroke. A head-mountable frame can assist a first responder in securing and guiding the coils and, along with fiducials, allow for automatic comparison of frequencies with the correct control data.

Medical diagnostic devices and related methods of use are described in which one or multiple coils in a sensor, each coil connected with an RLC circuit and frequency counter, are held against a patient's head at predetermined cranial locations. Frequencies of the RLC circuit are measured and compared against those taken from known, control heads, to determine whether there is a medical problem and what type of problem. In some instances, too high of frequencies can reveal pooled blood in the head, a sign of hemorrhagic stroke, while too low of frequencies imply lack of blood supply, a sign of ischemic stroke. A head-mountable frame can assist a first responder in securing and guiding the coils and, along with fiducials, allow for automatic comparison of frequencies with the correct control data.

Measurements of an arbitrary magnetic field having one or more magnetic field components are acquired from a plurality of magnetometers, and a generic model of at least one of the one or more magnetic field components of the arbitrary magnetic field is generated in the vicinity of the magnetometers. The generic magnetic field model comprises an initial number of different basis functions. Maxwell's equations are applied to the generic magnetic field model to reduce the initial number of different basis functions, thereby yielding a Maxwell-constrained model of the magnetic field component(s) of the arbitrary magnetic field, and the magnetic field component(s) of the arbitrary magnetic field are estimated at each of at least one of the magnetometers based on the constrained magnetic field model and the arbitrary magnetic field measurements acquired from each magnetometer.

Measurements of an arbitrary magnetic field having one or more magnetic field components are acquired from a plurality of magnetometers, and a generic model of at least one of the one or more magnetic field components of the arbitrary magnetic field is generated in the vicinity of the magnetometers. The generic magnetic field model comprises an initial number of different basis functions. Maxwell's equations are applied to the generic magnetic field model to reduce the initial number of different basis functions, thereby yielding a Maxwell-constrained model of the magnetic field component(s) of the arbitrary magnetic field, and the magnetic field component(s) of the arbitrary magnetic field are estimated at each of at least one of the magnetometers based on the constrained magnetic field model and the arbitrary magnetic field measurements acquired from each magnetometer.

A calibration system for a magnetometer having an unknown gain is disclosed. A calibration magnetic field is generated at a calibration frequency of a known amplitude at the magnetometer. A measurement of the calibrating magnetic field is reported by the magnetometer. A ratio of an amplitude of the calibration magnetic field measurement reported by the magnetometer and the known amplitude of the calibrating magnetic field at the magnetometer is computed. The unknown gain of the magnetometer is determined at least partially based on computed ratio.

A calibration system for a magnetometer having an unknown gain is disclosed. A calibration magnetic field is generated at a calibration frequency of a known amplitude at the magnetometer. A measurement of the calibrating magnetic field is reported by the magnetometer. A ratio of an amplitude of the calibration magnetic field measurement reported by the magnetometer and the known amplitude of the calibrating magnetic field at the magnetometer is computed. The unknown gain of the magnetometer is determined at least partially based on computed ratio.

An active shield magnetometry system comprises at least one magnetic field actuator configured for generating an actuated magnetic field that at least partially cancels an outside magnetic field, thereby yielding a total residual magnetic field. The active shield magnetometry system further comprises a plurality of magnetometers respectively configured for measuring the total residual magnetic field and outputting a plurality of total residual magnetic field measurements. The active shield magnetometry system further comprises at least one feedback control loop comprising at least one optimal linear controller configured for controlling the actuated magnetic field at least partially based on at least one of the plurality of total residual magnetic field measurements respectively output by at least one of the plurality of magnetometers.

An active shield magnetometry system comprises at least one magnetic field actuator configured for generating an actuated magnetic field that at least partially cancels an outside magnetic field, thereby yielding a total residual magnetic field. The active shield magnetometry system further comprises a plurality of magnetometers respectively configured for measuring the total residual magnetic field and outputting a plurality of total residual magnetic field measurements. The active shield magnetometry system further comprises at least one feedback control loop comprising at least one optimal linear controller configured for controlling the actuated magnetic field at least partially based on at least one of the plurality of total residual magnetic field measurements respectively output by at least one of the plurality of magnetometers.