Reliability-guided Rayleigh backscattering spectrum correlation method for distributed strain measurements in optical fibres. Issue 5 (12th March 2019)

• Record Type: Journal Article
• Authors: Suo, Liujia; Lei, Zhenkun; Takezawa, Akihiro; Wu, Zhanjun
• Is Part Of: Journal of modern optics. Volume 66:Issue 5(2019)
• Page Start: 512
• Page End: 520
• Publication Date: 2019-03-12
• Subjects: Distributed strain measurement -- high reliability -- optical frequency domain reflectometry -- Rayleigh backscattering spectrum shift -- cross correlation; Optics -- Periodicals; 535
• DOI: 10.1080/09500340.2018.1549288
• Languages: English
• ISSNs: 0950-0340

Abstract

Abstract : We present a method of reliability-guided Rayleigh backscattering correlation for distributed strain measurements in optical fibres. In this method, a reference Rayleigh-backscattering-spectrum (RBS) range that is larger than the measurement RBS range is defined to extend the matching range. To obtain the best match between reference and measurement spectra, the zero-mean normalized cross correlation (ZNCC) is employed to evaluate the degree of similarity. The path for searching the maximum similarity matching pattern is guided using Newton's iteration method. The reliability of the computed RBS shift is identified by the ZNCC coefficient distribution. The experiments show that the proposed method has high reliability in computing the RBS shift. Even at a relatively large strain (e.g. 5000 µϵ), the proposed method can stably demodulate the strain within a relative error of −1% and a spatial resolution of 1.6 cm over a 22-meter-long single-mode fibre. This shows that the proposed method has an advantage in regard to relatively large strain measurements.