Fiber-Optic Displacement Sensor Based On Fabry-Pérot Interferometer

Abstract

This paper describes a simple and inexpensive fiber-optic sensor for dynamic displacement measurement with sub-nanometer resolution. The principle is based on creating a resonator cavity between measured surface and a single-mode fiber, working as a Fabry-Pérot interferometer. The fundamental principles like diffraction, spatial filtration or the role of reflectivity are analyzed theoretically and their effect on the sensitivity is explained. The sensor is then tested experimentally with an uncoated fiber tip and a gold mirror. Based on the spectral analysis, the effect of working distance on interference visibility is explained.