Extrinsic Fabry-Perot sensor for strain and crack opening displacement measurements from -200 to 900 degrees C

Abstract

The authors present the design of a fiber optic extrinsic Fabry-Perot interferometric sensor element and its operation in several applications. The sensor has been demonstrated in a coal-fired combustor for the measurement of both thermally induced strains and crack opening displacements in ceramic materials. As a strain sensor, the device is demonstrated at temperatures ranging from -200 to 900 degrees C. It is shown that a Fabry-Perot strain gage with a one centimetre gage length can be operated in differential mode with 0.01 microstrain resolution in real-time, and in an absolute mode with 0.5 microstrain resolution with a three-second scan time.