Detecting broadside and directional acoustic signals with a fiber optical distributed acoustic sensing (DAS) assembly

摘要

A Distributed Acoustic Sensing(DAS) fiber optical assembly comprises adjacent lengths of optical fiber A, B with different directional acoustic sensitivities, for example by providing the first length of optical fiber A with a first coating 35, such as acrylate, and the second length of optical fiber B with a second coating 36, such as copper, wherein the first and second coatings 35 and 36 may be selected such that the Poisson's ratio of the first length of coated fiber A is different from the Poisson's ratio of the second length of coated fiber B. The different Poisson's ratios and/or other properties of the adjacent lengths of optical fiber A and B improve their directional acoustic sensitivity and their ability to detect broadside (radial) acoustic waves.

主权项

1. A Distributed Acoustic Sensing (DAS) fiber optical assembly comprising at least two lengths of adjacent optical fiber with different directional acoustic sensitivities wherein the at least two lengths of adjacent optical fiber comprise a first length of optical fiber with a first ratio between its axial and radial acoustic sensitivity and a second length of optical fiber with a second ratio between its axial and radial acoustic sensitivity, wherein the second ratio is different from the first ratio.