Real-Time Strain Field Measurement Based on Dense Fiber Bragg Gratings Array

Real-time high spatial resolution fiber sensing is crucial for achieving high-precision strain measurement for various applications. Bulky optical frequency-domain reflectometry is one of the mainstream devices capable of achieving spatial resolution at the micrometer level, but their relatively expensive tunable laser and poor real-time performance are becoming the bottlenecks to hinder the development of ultracompact and fast response strain field measurement systems that are highly demanded in practice. Herein, we proposed a real-time and low-cost accurate strain field measurement methodology based on dense fiber Bragg gratings (FBGs) array with wavelength division multiplexing, in which the system showed a flexibly adjustable spatial resolution down to 10 mm and ultrahigh strain resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.83~\mu \varepsilon $ </tex-math></inline-formula>. Such strain field measurement methodology has been successfully applied to 2-D irregular shape sensing with a maximum relative reconstruction error of 0.16% and dynamic strain field monitoring with 50-Hz sampling rate. The high-density FBGs array based on strain field measurement systems could have the capability of cost-effective and robust practicality.