Magnetically shielded magnetic sensor with squid and ground plane

Patent 5600243 Issued on February 4, 1997. Estimated Expiration Date:

March 17, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Apparatus for multi-channel measurement of weak magnetic fields with squids and superconducting gradiometers on individual detachable assemblies, and method of manufacture
Patent #: 5012190
Issued on: 04/30/1991
Inventor: Dossel

Multispectral superconductive quantum detector
Patent #: 5185527
Issued on: 02/09/1993
Inventor: Bluzer

Superconducting circuit having a rectifier for converting a bipolar signal to a unipolar signal
Patent #: 5287057
Issued on: 02/15/1994
Inventor: Gotoh

Geometrically and electrically balanaced dc SQUID system having a pair of intersecting slits Patent #: 5319307
Issued on: 06/07/1994
Inventor: Simmonds

Inventor

Colclough, Mark S.

Assignee

Conductus, Inc.

Application

No. 403728 filed on 03/17/1995

US Classes:

324/248, Superconductive magnetometers505/846Using superconductive quantum interference device (i.e., SQUID): (Class 324/248)

Examiners

Primary: Strecker, Gerard R.

Attorney, Agent or Firm

DeFranco, Esq.; Judith A.

Foreign Patent References

0313132 EP 04/13/1989
0327123 EP 09/13/1989
567386 EP 10/13/1993

International Class

G01R 033/035

Abstract

A coupling structure for coupling a feedback signal to a superconducting quantum interference device (SQUID) by mutual inductance. In one embodiment the SQUID loop (A) is shielded from external magnetic fields perpendicular to it by a superconducting ground plane (B) at all points except for the pick-up loop (C). A feedback signal is coupled to the SQUID loop (A) by a feedback loop (D) which has a mutual inductance with the SQUID loop (A). During operation, the feedback loop (D) conducts a current in only one direction around the SQUID loop (A). This geometry ensures that the SQUID loop (A) is shielded from external magnetic fields, except at the pick-up loop (C), by the ground plane, and is balanced against fields parallel to the ground plane. The magnetic field produced by the current in the feedback coil (D) is small far from the SQUID (A). The feedback loop (D) is connected to exterior feedback electronics.