Distributed sensor array and method using a pulsed signal source

US4770535A · kind A · utility

Assignee

• The Board of Trustees of the Leland Stanford Junior University · US

Inventors

• Byoung Y. Kim · Menlo Park, US
• Moshe Tur · Nes Ziona, IL
• Janet L. Brooks · Mountain View, US
• Kenneth A. Fesler · Sunnyvale, US
• Herbert J. Shaw · Stanford, US

Key dates

• Filing date: Jun 23, 1986
• Grant date: Sep 13, 1988
• Expiry date: Jun 23, 2006

Classification

• Technology area (CPC G): Physics
• CPC primary: G01D5/35383
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A distributed sensor system using pulsed optical signals optionally produced by a short coherence length source to provide a phase difference output signal representative of conditions affecting a selected sensor. In one preferred embodiment, an array of fiber-optic sensors are organized in a ladder configuration, with the sensors positioned in spaced relation and defining the rungs of the ladder. Light pulses transmitted through the sensors are multiplexed onto a return arm of the ladder. The multiplexed signals are received by an optical fiber compensating interferometer which coherently couples portions of adjacent multiplexed light signals to produce a phase difference signal representing conditions influencing selected sensors. In other preferred embodiments, the system is configured to define a plurality of adjacent Mach-Zehnder interferometers which provide output signal pairs which coherently couple to yield a phase difference signal directly representing the environmental effects on a particular sensor. Functional equivalents of the Mach-Zehnder interferometer configurations comprise configurations including adjacent Michelson interferometers. A phase and amplitude modulat…