Apparatus for measuring weak static magnetic field using superconduction strips and a SQUID magnetometer

• US 5,184,072 A
• Filed: 09/19/1991
• Issued: 02/02/1993
• Est. Priority Date: 09/20/1990
• Status: Expired due to Fees

• Current Assignee: GENG, QIQUAN (5%), Research Development Corporation Of Japan (Japan Science And Technology Agency), Nihon Shinku Gijutsu Kabushiki Kaisha (Ulvac Incorporated)
• Original Assignee: Junpei Yuyama, Qiquan Geng, UAB Research Foundation (University of Alabama System)
• Inventors: Yuyama, Junpei, Geng, Qiquan, Chihara, Kazunori, Minami, Hirofumi, Goto, Eiichi
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US07/762,381
• Time in Patent Office: 502 Days
• Field of Search: 324/248, 505/845, 505/846
• US Class Current: 324/248
• CPC Class Codes: G01R 33/0358 coupling the flux to the SQUID gradiometer coils G01R33/022; coils with superconductive winding H01F6/06
• CPC Class Codes: Y10S 505/845 Magnetometer

Abstract

A magnetic field measurement system including a pick-up coil is not moved but fixed. Strips of superconducting material are arranged in a plane with narrow slits between the strips. The strips are moved very near the pick-up coil along the plane. From output variations of a SQUID magnetometer during the movement, a magnitude of a static field perpendicular to the plane of the strips is obtained.

Claims

1. An apparatus for measuring a weak static magnetic field, including a superconducting quantum interference device (SQUID) and a pick-up coil magnetically coupled thereto, said apparatus comprising:

an array of superconducting strips which are arranged in a plane and separated by narrow slits, and

means for moving said array in a direction parallel to the plane and at a small distance from the pick-up coil.

2. The apparatus according to claim 1, wherein said pick-up coil is fixed with respect to said moving array.

3. The apparatus according to claim 1, further comprising a means for measuring output variations from said superconducting quantum interference device (SQUID), and thereby obtaining a magnitude of said magnetic field perpendicular to said plane.

4. The apparatus according to claim 1, wherein said array of superconducting strips are disposed within a wafer holder which is moved with respect to said pick-up coil by a driving means.

5. The apparatus according to claim 1, wherein said pick-up coil is mounted on a floating head.

6. The apparatus according to claim 1, wherein said superconducting quantum interference device (SQUID) detects an absolute value of said magnetic field.