Magnetic field measurement or recording systems with validation using optical tracking data
A magnetic field recording system includes a headgear for a user; optically pumped magnetometers (OPMs) disposed in or on the headgear to detect magnetic fields and, in response to the detection, produce magnetic field data; at least one sensing modality including an optical sensing modality having at least one light source and at least one camera or light detector to receive light reflected or directed from the user and to produce an optical data stream; a tracking unit to receive the optical data stream and track a position or orientation of the headgear or user; a system controller to control operation of the OPMs and receive, from the tracking unit, the position or orientation of the headgear or user; and a processor to receive the optical data stream and the magnetic field data from the OPMs and analyze the magnetic field data using the optical data stream for validation.
1. A magnetic field recording system, comprising:
a headgear configured to be placed on a user;
a plurality of optically pumped magnetometers (OPMs) disposed in or on the headgear and configured to detect magnetic fields and, in response to the detection, produce magnetic field data;
at least one sensing modality comprising an optical sensing modality comprising at least one light source and at least one camera or light detector configured to receive light reflected or directed from the user and to produce an optical data stream;
a tracking unit configured to receive at least the optical data stream and to track a position or orientation of the headgear or user;
a system controller configured to control operation of the OPMs and to receive, from the tracking unit, the position or orientation of the headgear or user; and
a processor configured to receive the optical data stream and the magnetic field data from the OPMs, wherein the processor is configured to analyze the magnetic field data using the optical data stream for validation.
2. The magnetic field recording system of claim 1 , wherein the processor is configured to identify facial movements using the optical data stream.
3. The magnetic field recording system of claim 1 , wherein the processor is configured to anonymize the optical data stream to reduce identification of the user while maintaining contours of facial landmarks.
4. The magnetic field recording system of claim 1 , wherein the processor is configured to determine position of a head of the user relative to the headgear.
5. The magnetic field recording system of claim 4 , wherein the processor is configured to enhance localization of the detected magnetic fields using the determined position of the head of the user relative to the headgear.
6. The magnetic field recording system of claim 1 , wherein the at least one sensing modality further comprises at least one of the following:
i) a magnetic sensing modality comprising at least one electromagnetic coil configured to produce magnetic field tones at one or more frequencies and at least one magnetic field sensor configured for placement on the user to detect the magnetic field tones and to produce a magnetic data stream, or
ii) an inertial sensing modality comprising at least one inertial sensor configured for placement on a user and to produce an inertial data stream.
7. The magnetic field recording system of claim 1 , further comprising a passively shielded enclosure comprising a plurality of walls defining the passively shielded enclosure, each of the plurality of walls comprising passive magnetic shielding material to reduce an ambient background magnetic field within the passively shielded enclosure.
8. The magnetic field recording system of claim 7 , further comprising a plurality of active shield coils distributed within the passively shielded enclosure and configured to further reduce the ambient background magnetic field within the passively shielded enclosure.
9. The magnetic field recording system of claim 7 , further comprising at least one first fiducial marker disposed on at least one of the walls of the passively shielded enclosure.
10. The magnetic field recording system of claim 9 , wherein the optical sensing modality further comprises at least one second fiducial marker for placement on the headgear or the OPMs and configured to reflect light from the at least one light source.
11. The magnetic field recording system of claim 10 , wherein the tracking unit is configured to determine a position of the at least one second fiducial marker relative to the at least one first fiducial marker to monitor movement of the user.
12. The magnetic field recording system of claim 1 , wherein the tracking unit is configured to utilize at least one feature of the user as a fiducial marker for the optical sensing modality.
13. The magnetic field recording system of claim 1 , wherein the tracking unit is configured to track head-to-headgear co-registration.
14. The magnetic field recoding system of claim 1 , wherein the tracking unit is configured to continuously track head-to-headgear co-registration.
15. The magnetic field recording system of claim 1 , wherein the processor is part of the tracking unit or the system controller.
16. A method of recording biomagnetic fields using the magnetic field recording system of claim 1 , the method comprising:
disposing the headgear on the user;
tracking the position or orientation of the user, helmet, or OPM modules using the at least one sensing modality and the tracking unit;
recording the biomagnetic fields using the OPMs to produce the magnetic field data; and
associating the biomagnetic fields with biological regions of the user using at least the tracked position or orientation.
17. The method of claim 16 , further comprising processing the optical data stream to validate the magnetic field data.
18. The method of claim 17 , wherein processing the optical data stream comprises identifying facial movement using the optical data stream and associating at least a portion of the magnetic field data with those facial movements as part of validating the magnetic field data.
19. The method of claim 17 , wherein processing the optical data stream comprises anonymizing the optical data stream to reduce identification of the user while maintaining contours of facial landmarks.
20. The method of claim 19 , wherein anonymizing the optical data stream comprises placing a mask over a face of the user in the optical data stream and overlaying contours of facial landmarks on the mask.
21. The method of claim 16 , wherein tracking the position or orientation of the user, helmet, or OPM modules comprises determining a position of the user, helmet, or OPM modules relative to a stationary fiducial marker disposed in a passively shielded enclosure within which the user is positioned.
22. The method of claim 16 , wherein tracking the position or orientation of the user, helmet, or OPM modules comprises continuously determining a position of the user, helmet, or OPM modules relative to a stationary fiducial marker disposed in a passively shielded enclosure within which the user is positioned.