High-precision optical fiber liquid-level sensor based on a sensitive and extrinsic Fabry-Perot interferometric cavity

Abstract

A novel intensity-based optical fiber liquid-level sensor based on a sensitive and extrinsic Fabry-Perot (F-P) interferometric cavity is described in this paper. The novel sensing schemes combines the advantages of both interferometry sensors and intensity-based sensors. The sensor operates on a single fiber F-P interferometric cavity with a DFB-LD light source. The elastic silicon slice replaces conventional reflected multimode optical fiber in extrinsic optical fiber F-P sensor as sensing element. Several steps have been taken to eliminate or restrain temperature effect influencing on the sensing system. Experimental results indicate a precision as high as 1.2mm of a full scale 3.5m (water) is obtained.The optimized sensor can be used in explosive and flammable environment to measure liquid-level continuously and accurately.