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:
Sep. 11, 1990
Filed:
Feb. 23, 1989
NGK Insulators, Ltd., , JP;
Abstract
A system for optically measuring the strength of an AC magnetic field, by an apparatus which includes a sensing head having a magnetooptical element, a polarizer and an analyzer, a light source device for producing a light beam to be transmitted through the sensing head, and a light-sensitive device for converting an optical output of the sensing head into an electric signal. The light beam is modulated by the sensing head to provide the optical output indicative of the strength of the AC magnetic field to which the magnetooptical element is exposed. The magnetooptical element is exposed also to a reference magnetic field different from the AC magnetic field, to thereby bias the light beam while being transmitted through the magnetooptical element. A first and a second component (E.omega.) and (E.sub.2 .omega.) of the electric signal is produced by the light-sensitive device. The first component (E.omega.) has the same angular frequency as that of the AC magnetic field, while the second component (E.sub.2 .omega.) has an angular frequency which is two times that of the AC magnetic field. The strength of the AC magnetic field is determined based on the first and second components (E.omega.) and (E.sub.2 .omega.).