High Spatial Resolution and Wide Strain Measurement of Optical Frequency Domain Reflectometry Based on Correlation Spectrum Self-Compensation Method

The strain measurement range of an optical frequency domain reflectometry (OFDR) system is constrained by spatial resolution, which is affected by shifts in the distance domain. In this paper, a novel correlation spectrum self-compensation scheme based the reference signal is introduced, which improves the alignment between the reference and measurement signals along the sensing fiber. This contrasts with traditional cross-correlation by directly analyzing the spectrum shifts between the reference and measurement signals. The spatial mismatch caused by overstretching of the fiber can be suppressed with the spatial moving of the reference signal so that the trade-off between spatial resolution and wide strain measurement range can be overcame. Experimental results demonstrate a strain gradient range from 1000 μϵ to 10000 μϵ free of outliers with a spatial resolution of 2 mm. The proposed method offers a new approach to simultaneously achieve wide strain measurement and high spatial resolution in OFDR systems. This marks a significant step forward in high-performance distributed strain sensing system, particularly for applications requiring both broad strain measurement and enhanced spatial resolution.