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Browse Prior Art Database

Three-Axis SQUID Magnetometer

IP.com Disclosure Number: IPCOM000043880D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Ketchen, MB: AUTHOR

Abstract

Three-axis SQUID (Superconducting Quantum Interference Device) magnetometers typically consist of three orthogonal superconducting pickup coils that are connected to three SQUID sensors located some distance away, in a shielded region. Three-axis magnetometers have also been made of three mutually orthogonal cylindrical SQUIDs, where the inductive loop of each SQUID serves as a single turn pickup coil. In order to overcome the difficult fabrication problems with these magnetometers, and the attendant cost, a three-axis magnetometer is described having more simplified structure that is easier to fabricate. This magnetometer has the same sensitivity as prior 3-axis magnetometers, but is fabricated as a single unit on a planar substrate.

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Three-Axis SQUID Magnetometer

Three-axis SQUID (Superconducting Quantum Interference Device) magnetometers typically consist of three orthogonal superconducting pickup coils that are connected to three SQUID sensors located some distance away, in a shielded region. Three-axis magnetometers have also been made of three mutually orthogonal cylindrical SQUIDs, where the inductive loop of each SQUID serves as a single turn pickup coil. In order to overcome the difficult fabrication problems with these magnetometers, and the attendant cost, a three-axis magnetometer is described having more simplified structure that is easier to fabricate. This magnetometer has the same sensitivity as prior 3-axis magnetometers, but is fabricated as a single unit on a planar substrate. It consists of two bridge SQUIDs and one planar SQUID oriented on a single Si chip, as shown in Fig. 1. Orthogonality of axes is assured by virtue of the design. In Fig. 1, the Si substrate 10 includes an x-axis bridge SQUID 12 and a y-axis bridge SQUID 14. A z-axis planar SQUID 16 is also provided. Junction/shunt areas 18 are located at the end of the bridge SQUIDs 12 and 14, and on one edge of the planar SQUID 16. The bridge SQUIDs 12 and 14 have a bridge inductive loop rather than a planar inductive loop, and are shown in cross-section in Fig. 2. These SQUIDs can be fabricated using conventional processes for making Josephson devices, except that a thick insulation layer 20 with feathered edges is re...