SQUID Gradiometer Using Planar Coupling
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
This article relates generally to gradiometers using superconducting quantum interference devices (SQUIDS) and, more particularly, to a technique of using planar coupling between the gradiometer and SQUID. Thin film gradiometers have significantly improved sensitivity due to decreased noise when constructed of a planar set of parallel or series-wound pick-up loops efficiently coupled to a planar, symmetric two-hole or figure-eight SQUID. Highly sensitive SQUID gradiometers principally employ pick-up loop designs of either series or parallel loop configurations, such as shown in Figs. 1 and 2, respectively. The net applied flux for the two pick-up loops 1 and 2 in Fig. 1 equals the difference in flux applied to the two loops and, for the parallel case of loops 3 and 4 (Fig. 2), the net applied flux is half that difference.