Unshielded pulsed pump magnetometers for biomagnetic measurements

A method of measuring biomagnetic signals of a biological subject in an unshielded measurement environment using a pulsed pump magnetometer (PPM), comprising:

• arranging one or more of the PPM at a desired location over a biological subject;
• operating the one or more of the PPM to detect a biomagnetic signal from the biological subject over a period of time;
• processing the detected biomagnetic signal to generate a result indicative of a characteristic or condition associated with the biological subject;
• wherein each of the one or more of the PPM comprises:
• at least one atomic vapor cell;
• at least one pulsed pump laser and at least one probe laser which is pulsed or operated continuously;
• and
• a magnetic field coil configured to generate a pulsed magnetic field that has a component parallel to a pump axis of one of the at least one pulsed pump laser, the magnetic field coil being configured to be turned off faster than a Larmor precession period of a gas in one of the at least one atomic vapor cell.