Two-dimensional distributed strain sensing with an Archimedean spiral arrangement in optical frequency domain reflectometry

Abstract

We demonstrate a distributed two-dimensional (2D) strain-sensing system in optical frequency domain reflectometry (OFDR) with an Archimedean spiral arrangement of the sensing fiber. The Archimedean spiral describes a simple relationship between the radial radius and polar angle, such that each circle (the polar angle from 0 to 2π) can sense the 2D strain in all directions. The strain between two adjacent circles can also be easily obtained because an Archimedean spiral facilitates sensing of every angle covering the full 2D range. Based on the mathematical relation of Archimedean spirals, we deduce the relationship between the one-dimensional position of the sensing fiber and 2D distribution in polar coordinates. The results of the experiment show that an Archimedean spiral arrangement system can achieve 2D strain sensing with different strain load angles.