Fiber Optic Based Distributed Mechanical Vibration Sensing

Area of Science:

• Optical Engineering
• Sensor Technology
• Telecommunications

Background:

• Distributed sensing systems are crucial for monitoring mechanical vibrations over long distances.
• Standard telecommunication single-mode optical fibers offer a potential infrastructure for such sensing applications.
• Existing methods may have limitations in range, sensitivity, or classification capabilities.

Purpose of the Study:

• To describe a novel distributed long-range sensing system for mechanical vibrations.
• To demonstrate the system's capability in detecting, localizing, and classifying diverse vibration sources.
• To present the design and performance of a two-fiber sensor unit for extended sensing range.

Main Methods:

• Utilized phase-sensitive optical time-domain reflectometry (ϕ-OTDR) as the core sensing technology.
• Designed and constructed sensing system components for laboratory and real-world deployment.
• Tested the system over an 88 km telecommunication optical link and with a novel two-fiber sensor unit.

Main Results:

• Successfully detected, localized, and classified various vibration events, including human and vehicular movement.
• Demonstrated system functionality in both laboratory settings and an 88 km deployed optical link.
• Presented initial measurement results from a newly designed two-fiber sensor unit offering a doubled sensing range.

Conclusions:

• The developed ϕ-OTDR-based distributed sensing system is effective for long-range mechanical vibration monitoring.
• The system shows promise for diverse applications requiring detection and classification of vibration sources.
• The two-fiber sensor unit design represents a viable approach to enhance the sensing range.