Crack monitoring using short-gauged Brillouin fiber optic sensor

Detection and quantification of cracks for various civil infrastructures on a large scale are difficult both technologically and economically through current sensing methodologies. This study presents a novel fiber-optic sensor named short-gauged Brillouin fiber optic sensor, which enables basic Brillouin-based analyzers to achieve early crack detection and accurate crack width measurement. The concept and design of the proposed sensor are firstly introduced, followed by respective instrumentation procedures. On this basis, theoretical deduction and numerical simulations of the crack-induced Brillouin gain spectrum (BGS) response using the proposed sensor are carried out, verified subsequently by controlled laboratory tests. The measured BGS responses are then leveraged for crack detection and quantification. A peak-fitting-based methodology was adopted to analyze the BGS data to achieve accurate crack width measurement. The proposed methodology may facilitate economical long-distance distributed crack sensing and quantification for various infrastructures as a generic technique.