Research on the OFDR strain measurement method based on similarity features of dual-segment RSS

Area of Science:

• Fiber Optic Sensing Technology
• Optical Measurement Techniques
• Materials Science and Engineering

Background:

• Optical frequency domain reflectometry (OFDR) is a key technology for fiber optic sensing, enabling strain, vibration, and temperature measurements.
• Applications include deformation analysis of aerospace components and structural health monitoring of bridges.
• Large strains can cause significant demodulation errors due to reduced signal similarity.

Purpose of the Study:

• To analyze the causes of strain demodulation errors under large strain conditions.
• To propose a new strain measurement method addressing signal similarity issues in OFDR.
• To develop an optimized strain edge demodulation technique for enhanced accuracy.

Main Methods:

• A strain measurement method utilizing the similarity feature of a double-segment Rayleigh scattering spectrum was developed.
• Local segments of the reference signal were used as fingerprint spectra for similarity matching.
• A strain edge optimization method with automatic sliding window center adjustment was implemented.

Main Results:

• The proposed method demonstrated improved strain measurement accuracy compared to traditional techniques.
• A sensing unit length of 32.6 mm and a frequency modulation bandwidth of 5 nm were achieved.
• The measurement range extended to ±2000 µɛ to ±2500 µɛ, with measurable spectral offset increasing from 48% to 60% and a maximum standard deviation of 1.9 µɛ.

Conclusions:

• The novel OFDR strain measurement method effectively reduces demodulation errors under large strains.
• The technique offers enhanced precision and a wider measurement range for critical structural monitoring.
• This advancement holds significant potential for applications requiring high-accuracy deformation analysis.