The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 06, 1990
Filed:
Feb. 08, 1988
Hitachi, Ltd., Tokyo, JP;
Abstract
A SQUID for detecting a weak magnetic field is constructed of a sensor coil which detects a signal magnetic flux, and a superconducting loop which is magnetically coupled with the sensor coil to generate a periodic voltage corresponding to an interlinking magnetic flux from the sensor coil. The periodic voltage from the SQUID is amplified, and is taken out. The periodic voltage taken out is synchronously detected by a phase-sensitive detecting amplifier. The synchronously-detected signal is converted into a light signal, which is fed back to the SQUID. The light signal fed back is converted into an electric signal by a superconducting phototransistor which is arranged in a cryogenic atmosphere. A magnetic flux corresponding to the electric signal from the superconducting phototransistor is fed back to the superconducting loop by a feedback coil.