Patent ID: 6778717
Filing Date: 2004-08-17
Classification: G01M

Abstract:
A method of monitoring a structure to locate the position of an event, including the steps of:launching light into a waveguide so that the light is caused to propagate in both directions along the waveguide to thereby provide counter-propagating optical signals in the waveguide, the waveguide being capable of having the counter-propagating optical signals or some characteristic of the signals modified or effected by an external parameter caused by the event, to provide modified counter-propagating optical signals which continue to propagate along the waveguide; and substantially continuously and simultaneously monitoring the modified counter-propagating optical signals, so that when an event occurs, both of the modified counter-propagating optical signals effected by the external parameter are detected; and determining the time difference between the detection of the modified signals in order to determine the location of the event.