Continuously Swept Laser Fiber Bragg Grating Data Acquisition System (DAS) Capable of Operating in Extreme Environment

Abstract

Structural health monitoring (SHM) utilizing optical fiber sensing is attractive for various aerospace applications because of the lightweight nature of the fiber optics, the ability to cascade multiple sensors onto a single fiber, and its immunity to electromagnetic interference (EMI). Optical fiber sensing based on fiber Bragg gratings (FBGs) is an attractive candidate for strain and temperature sensing, especially in extreme environments such as a hypersonic flight. The National Aerospace and Space Administration (NASA) Armstrong Flight Research Center (AFRC) (Edwards, California) has more than two decades of experience integrating fiber-optic sensors into various flight aircraft as well as developing custom ruggedized interrogators to suit the requirements for each unique situation. This paper presents, in detail, a custom-built data acquisition system (DAS) capable of detecting not only FBGs but also Extrinsic Fabry-Perot Interferometers (EFPIs). Presented as well, and again in detail, are the system design, environmental testing under vibration, and thermal cycling.