Title :
Optical fiber feedback SQUID magnetometer
Author :
Naito, Seiichi ; Sampei, Yoshihiro ; Takahashi, Takahiro
Author_Institution :
Yokogawa Electr. Corp., Tokyo, Japan
fDate :
4/1/1989 12:00:00 AM
Abstract :
A description is given of an optical-fiber feedback superconducting quantum interference device (SQUID) magnetometer which was developed to improve electromagnetic interference characteristics. The SQUID consists of an RF SQUID control unit. Phase-locked pulse-width modulation (PWM) was used to construct a flux-locked-loop (FLL) circuit in the SQUID control unit. The operation of the optical fiber feedback SQUID is stable when a common mode voltage of AC 100 V/50 Hz is applied. It has an energy resolution of 1×10-28 J/Hz. The authors describe the measurement of an auditory evoked field from the human brain in a magnetically shielded room using the fiber feedback SQUID with a gradiometer-type pickup coil
Keywords :
SQUIDs; biomagnetism; biomedical measurement; electromagnetic interference; feedback; fibre optics; magnetometers; phase-locked loops; pulse width modulation; SQUID magnetometer; auditory evoked field; biomedical measurement; flux-locked-loop; gradiometer-type pickup coil; human brain; optical-fiber feedback; pulse-width modulation; Electromagnetic interference; Optical devices; Optical feedback; Optical fibers; Optical modulation; Optical pulses; Pulse width modulation; Radio frequency; SQUID magnetometers; Superconducting devices;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
