Remote displacement measurement using a passive interferometer with a fiber-optic link

Area of Science:

• Optical Physics
• Metrology
• Fiber Optic Sensing

Background:

• Accurate remote displacement measurement is crucial for various scientific and industrial applications.
• Traditional methods can be limited by environmental factors, optical losses, and dynamic range.

Purpose of the Study:

• To demonstrate a novel remote displacement measurement technique.
• To achieve high-precision tracking of cavity length using a multimode optical fiber link.

Main Methods:

• Utilized a Fabry-Perot sensing cavity whose length modulates the spectrum of a light-emitting diode (LED).
• Employed a tunable reference cavity to analyze the returning light signal via the fiber link.
• Implemented a closed-loop control system for precise tracking of the sensing cavity length.

Main Results:

• Achieved sub-picometer tracking precision (2 x 10^-12 m) for the sensing cavity length.
• Demonstrated a displacement measurement range of 2 x 10^-6 m.
• Validated the technique's compatibility with standard multimode fiber-optic components.

Conclusions:

• The proposed Fabry-Perot cavity sensor offers high immunity to optical losses.
• This method provides a large dynamic range for remote displacement sensing.
• The technique is suitable for applications requiring precise, remote optical metrology.