Fiber optic sensors for structural monitoring: a 30 year perspective

Thirty years ago the Air Force initiated Project Forecast II, a Sagnac fiber optic strain sensor had been used to measure strain fields internal to carbon composites provided by Douglas Aircraft and issues associated with monitoring the structural integrity of the McDonnell Douglas Space Station design all came together to initiate the new field of fiber optic smart structures. This tutorial paper is intended to provide a perspective of how the field originated and has evolved of the past 30 years.