High temperature fiber optic strain sensing

Abstract

Two high temperature fiber optic based strain sensors have been developed for use in a coal combustor environment. An intensity based sensor uses losses created by longitudinal misalignment as a sensing mechanism and has a maximum operating temperature of 700°C. An interferometric based sensor makes use of a Fabry-Perot cavity created by aligning two fibers in a splice tube with a small gap in between. The Fabry-Perot based sensors' maximum operating temperature is 950°C. Attachment methods and sensor design are discussed as well as the presentation of results from in situ testing.