On-line displacement measurement using a high stability multiplexed optical fiber interferometer system

A multiplexed optical fiber Michelson interferometers system for measurement of displacement is presented. This system employs fiber Bragg gratings (FBGs) and wavelength-division-multiplexing technique to multiplex two optical fiber interferometers together which share the same optical path of the main part of the optical system. When the Michelson interferometer which uses FBGs as reflective mirrors is stabilized by an electric feedback loop, the other interferometer which does the measurement work is also stabilized. An active phase tracking technique is applied for signal processing to achieve high resolution.