Gradient magnetometer having superconducting quantum interferometers

摘要

A gradient magnetometer (2) suitable for medical diagnostics or non-destructive material testing applications comprises a pair of cryogenically controlled superconducting quantum interferometers (SQUID) of this film single layer construction having identical loop antennas (3, 4) connected in parallel via a common conductor (5) and coupling element (5a) such as to enclose similar areas (F1, F2). A DC SQUID (9) having the loop antenna (6) spanning the coupling element (5a) incorporates two Josephson elements (7, 8) whose current density regulation nullifies the effect of the earth's magnetic field on measurements of gradient and a screening ring (15) shields the system against external transient disturbance.