Superconducting magnetometer with digital output.

摘要

A superconducting magnetic sensor includes a SQUID (10) for interlinking with an external magnetic flux, an A.C. bias circuit (11) for driving the SQUID with an A.C. bias current having a first frequency, a feedback circuit (15) supplied with output voltage pulses from the SQUID for calculating a difference between the total number of positive output voltage pulses and the total number of negative output voltage pulses and for producing a feedback magnetic flux in response thereto such that the external magnetic flux is canceled out by the feedback magnetic flux, and a modulation current source (12) for supplying a modulation current having a frequency substantially smaller than the frequency of the bias current and for producing a modulation magnetic flux in response to the modulation current such that the modulation magnetic flux interlinks with the SQUID.