Overview of Fiber Optic Sensors for NDT Applications

Abstract

Optical fiber sensors have seen an increased acceptance as well as a widespread use for structural sensing and monitoring in civil engineering, aerospace, marine, oil & gas, composites and smart structure applications. Optical fiber sensor operation and instrumentation have become well understood and developed. Fiber sensors are attractive sensing devices for non-destructive testing (NDT) applications given their small size, lightweight and dielectric glass construction that renders them immune to electrical noise and EM interference—unlike most conventional electronic sensing systems. To date, fiber sensors have been embedded inside composite materials to determine curing, internal stresses and deformations as well as to detect the onset of cracks and damage. Surface mounted devices allow for the on-line monitoring in real time of deformations and strains in a variety of test specimens. Furthermore, some specific fiber sensor types allow for multi-point sensing at different locations using a single fiber, or even continuous, distributed sensing of temperature and strain based on Raman and Brillouin scattering systems. This paper reviews the operating principles, sensor types, benefits and applications of optical fiber sensors for non-destructive testing of materials and structures in different fields such as composites, aerospace, civil engineering, oil & gas and others.