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. 04, 1993
Filed:
Aug. 29, 1991
Kent A Murphy, Roanoke, VA (US);
Ashish Vengsarkar, Ashville, NC (US);
Brian Fogg, Blacksburg, VA (US);
Jonathan Greene, Blacksburg, VA (US);
Richard O Claus, Christiansburg, VA (US);
Center for Innovative Technology, Herndon, VA (US);
VPI&SU, Blacksburg, VA (US);
Abstract
Two-mode, elliptical-core optic fibers with a permanent photo-induced index change are used as sensors with sensitivity varying as a function of length. The optic fiber sensors act as vibrational-mode filters thereby performing initial signal processing of the sensor signal. The sensors are based on photo-induced refractive index changes. These refractive index changes affect the differential phase modulation between the LP.sub.01 and the LP.sub.11.sup.even modes. The change in beat-length is dependent on the amount of strain induced in the fiber while the grating is being formed. The pattern is thus varied along the length of the fiber by straining the fiber in a specific fashion while the grating is being written. This changes the sensitivity, of the sensor along its length. By choosing an appropriate weighting function in the manufacture of the sensor, it is possible to implement vibrational-mode analysis, vibrational-mode filtering and other functions that are critical in control system applications.