Biomagnetic measurement system using high sensitivity SQUIDmagnetometers

摘要

PURPOSE: An apparatus for measuring a biomagnetic field using a high sensitive SQUID(Superconducting Quantum Interference Device) magnetometer is provided to simplify a driving circuit by using a double relaxation oscillating SQUID type magnetometer and remove a magnetic interference between channels by using an external feedback method. CONSTITUTION: A double relaxation oscillating SQUID is serially connected to a signal SQUID(1) and a reference junction(2). The double relaxation oscillating SQUID is connected in parallel to a resistance(3) and an inductor(4). A DC front-end amplifier(12) is connected to the reference junction(2) in order to detect an output of the SQUID. Namely, an RF voltage pulse of 1 GHz is generated by AC current(11). At this time, an output voltage of SQUID is detected from both ends of the reference junction(2) by using the DC front-end amplifier(12). A left coil is formed with a detection coil(6), an input coil(5), and a magnetic flux transformer(8) including a feedback coil(7).