Apparatus and method for monitoring a structure using a counter-propagating signal method for locating events

• US 6,778,717 B2
• Filed: 04/29/2003
• Issued: 08/17/2004
• Est. Priority Date: 12/18/1998
• Status: Expired due to Term

• Current Assignee: Future Fibre Technologies Pty Limited
• Original Assignee: Future Fibre Technologies Pty Limited
• Inventors: Tapanes, Edward E., Goode, Jason R, Katsifolis, Jim
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): Suchecki, Krystyna
• Application Number:
  US10/426,114
• Publication Number:
  US 20030198425A1
• Time in Patent Office: 476 Days
• Field of Search: 356/477, 356/483, 356/450, 356/32, 356/34, 356/478, 356/482, 356/502, 356/498, 356/460, 385/12-13, 250/227-4-2, 250/550
• US Class Current: 385/12
• CPC Class Codes: G01M 11/083 by using an optical fiber in contact with the device under test [DUT]
• CPC Class Codes: G01M 11/3109 Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR
• CPC Class Codes: G01M 11/39 in which light is projected from both sides of the fiber or waveguide end-face
• CPC Class Codes: G01M 5/0025 of elongated objects, e.g. pipes, masts, towers or railways G01M5/0058 takes precedence
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0091 by using electromagnetic excitation or detection

Abstract

A method and apparatus for monitoring a structure and for locating the position of an event including a light source, a waveguide, and a detector means. The waveguide receives light from the light source so that the light is caused to propagate in counter-propagating optical signals in the waveguide. The waveguide includes the counter-propagating optical signals or some characteristic of the signals modified or effected by an external parameter caused by or indicative of the event to provide modified counter-propagating optical signals. The detector means detects the modified counter-propagating optical signals effected by the parameter and determines the time delay or difference between the modified counter-propagating optical signals in order to determine the location of the event.

Claims

1. 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.

2. The method of claim 1 wherein the light is launched into both ends of the waveguide to provide the counter-propagating signals.

3. The method of claim 1 wherein the light is launched into both ends of the waveguide from a single light source.

4. The method of claim 1 wherein the external parameter is quantified and/or identified from the modified signals.

8. The method of claim 1 wherein the waveguide has two ends and substantially continuously monitoring the modified counter-propagating optical signals effected by the external parameter includes concurrently monitoring a first photodetector coupled to one of the two ends and a second photodetector coupled to another of the two ends.

5. A method of monitoring an optical fibre communication link into which data signals are launched and from which the data signals are received, to locate the position of a disturbance to the link, including the steps of;

launching light into the link so that the light is caused to propagate in both directions along the link to thereby provide counter-propagating optical signals in the link, the link being capable of having the counter-propagating optical signals or some characteristic of the signals modified or effected by the disturbance to provide modified counter-propagating optical signals which continue to propagate along the link; 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 disturbance are detected; and

determining the time difference between the detection of the modified signals in order to determine the location of the disturbance.

6. The method of claim 5 wherein the light is launched into both ends of the link to provide the counter-propagating signals.

7. The method of claim 5 wherein the light is launched into both ends of the link from a single light source.

9. The method of claim 5 wherein the optical fibre communication link has two ends and substantially continuously monitoring the modified counter-propagating optical signals effected by the disturbance includes concurrently monitoring a first photodetector coupled to one of the two ends and a second photodetector coupled to another of the two ends.