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High-resolution absolute frequency referenced fiber optic sensor for quasi-static strain sensing
Timothy T-Y Lam1, Jong H Chow, Daniel A Shaddock
1Centre for Gravitational Physics, Department of Quantum Science, The Australian National University, 0200, Building 38 Science Road, Canberra, Australian Capital Territory, Australia. timothy.lam@anu.edu.au
Applied Optics
|July 22, 2010
Summary
This study introduces a novel fiber optic strain sensing system. It achieves ultra-low frequency strain resolution below nanostrain using a frequency-locked laser and a molecular reference.
Area of Science:
- Physics
- Optical Engineering
- Metrology
Background:
- Accurate measurement of low-frequency strain is crucial for various scientific and engineering applications.
- Existing fiber optic sensing systems face limitations in achieving high resolution at very low frequencies.
Purpose of the Study:
- To develop a quasi-static fiber optic strain sensing system with enhanced sensitivity and low-frequency performance.
- To demonstrate strain resolution below nanostrain at frequencies down to 20 mHz.
Main Methods:
- Utilizing a telecom-grade distributed feedback continuous-wave (CW) diode laser locked to a fiber Fabry-Perot sensor.
- Employing an H(13)C(14)N absorption line as a precise frequency reference.
- Transferring detected strain signals onto the laser for extraction of low-frequency data.
Main Results:
- Achieved strain resolution below nanostrain.
- Demonstrated sensing capability at frequencies as low as 20 mHz.
- Validated the system's accuracy through the use of a molecular absorption line reference.
Conclusions:
- The developed fiber optic strain sensing system offers unprecedented low-frequency resolution.
- The combination of laser locking and molecular referencing provides a robust method for high-precision quasi-static strain measurement.
- This technology has potential applications in geophysics, structural health monitoring, and fundamental physics research.
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