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:
May. 12, 1987
Filed:
Feb. 20, 1986
Philip Extance, Shirley, GB;
Roger E Jones, Little Shelford, GB;
STC plc, London, GB;
Abstract
Two portions (B,C) of one arm of an optical fibre Mach-Zehnder interferometer are magnetically sensitized and each has applied thereto an a.c. bias fields at a respective different frequency (w.sub.1, w.sub.2). One portion (A) of the other arm of the interferometer is magnetically sensitized and has two a.c. bias fields applied thereto, each at one of the different frequencies (w.sub.1,w.sub.2). The fields for portion A and C are aligned with a first direction (x) whereas those for A and B are parallel, A and B being separated in a second direction (y). The detected output of the interferometer at frequency w.sub.1 is related to the magnetic gradient in the y direction, whereas the detected output at frequency w.sub.2 is related to the magnetic gradient in the x direction. Thus using two bias frequencies allows one interferometer to be used to detect two gradients (FIG. 8).