A distributed optical fiber bi-directional strain-displacement sensor*

Abstract

Abstract A distributed optical fiber strain-displacement sensor is developed, which consists of an optical fibergauge of strain-displacement and an optical time domain reflectometer (OTDR). The operational principle is the modulation of fiber loss in OTDR, i. e. the strain and displacement in monitoring position are obtained from the bending loss of optical fiber bonded on the optical fiber gaugeof strain-displacement. After examining the strain and displacement in the cantilever and the microdisplacement rack respectively, the result indicates that the distributed optical fiber gauge of strain-displacement can monitor strains or displacements in different sensitive lengths. The key technique for measuring bi-directional strain-displacement is the pretreatment of bending of the freely suspended optical fibers, which can be identified with OTDR by inserting time delay optical fiber.