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:
Feb. 27, 1990
Filed:
Aug. 31, 1988
Lawrence R Dunn, Flowery Branch, GA (US);
Ian A White, Roswell, GA (US);
Willard C White, III, Doraville, GA (US);
American Telephone and Telegraph Company, AT&T Bell laboratories, Murray Hill, NJ (US);
Abstract
An optical fiber sensing system for detecting intrusion of optical fiber or optical fiber cables includes an interferometric arrangement. Two ports (28, 30) of a four port splitter (25) are connected to a source (26) of optical power such as a laser, for example, and to a detector (32). The other two ports (46, 48) are connected to ends of a length (50) of monitoring optical fiber. An input signal to the splitter is split with one subsignal being directed in one direction around the length of optical fiber which serves as a common path between the two ports. The other signal is caused to travel around the common path in an opposite direction. The split signals are recombined in the splitter and their phase difference measured as a detectable pattern by the detector. Should there be intrusion of the optical fiber or a cable containing the monitoring optical fiber, the pattern which is detected will change a significant amount.