PM fiber based sensing tapes with automated 45° birefringence axis alignment for distributed force/pressure sensing

Area of Science:

• Fiber optics
• Sensors and sensing technology
• Materials science

Background:

• Polarization-maintaining (PM) fibers offer potential for distributed force and pressure sensing.
• Optimal sensitivity requires the PM fiber's birefringence axis to be oriented at 45° to the applied force/pressure.
• Achieving precise, long-length 45° axis orientation in PM fibers presents a significant practical challenge.

Purpose of the Study:

• To develop the first equipment and process for fabricating PM fiber-based sensing tapes.
• To enable automatic adjustment of the PM fiber axis orientation to 45° relative to the tape surface.
• To demonstrate the capability of these sensing tapes for distributed force and pressure measurements.

Main Methods:

• Development of a machine vision system for real-time fiber axis orientation determination.
• Integration of a feedback loop controlling a fiber rotation apparatus for precise axis alignment.
• Automated fixation of the oriented PM fiber onto a transparent PET tape using UV epoxy.
• Validation using a distributed polarization crosstalk analyzer (DPXA).

Main Results:

• Successful fabrication of a 70-m-long PM fiber sensing tape with a consistent 45° ± 3° axis orientation.
• Validation of the tape's performance using DPXA, confirming accurate axis orientation.
• Demonstration of distributed transversal load sensing with high measurement uniformity (0.62 dB standard deviation for 100g weights).

Conclusions:

• The developed equipment and process effectively produce PM fiber sensing tapes with precise 45° axis orientation.
• These sensing tapes are suitable for distributed force sensing with high accuracy and uniformity.
• The technology holds promise for future applications in distributed pressure sensing with appropriate fixture design.