Patent attributes
A magnetic field measurement apparatus which reduces an interference magnetic field entering into a pick-up coil is provided. The magnetic field measurement apparatus includes a superconducting quantum interference device (SQUID) magnetometer having a pick-up coil for picking up a magnetic field generated from an examination object, a SQUID control unit for controlling the SQUID magnetometer, a magnetometer for picking up the interference magnetic field, a magnetometer control unit for controlling the magnetometer, a modulation circuit, a current converter, a current amount adjusting device, a coil which is positioned outside the pick-up coil and through which the current thus adjusted by the current amount adjusting device flows, a demodulation circuit, a low-pass filter (LPF) for extracting a low frequency element of the output voltage from the demodulation circuit, and a subtraction circuit for subtracting the output of the LPF from the output of the SQUID control unit.
