Dynamic displacement measurements with a stabilized fiber Michelson interferometer based on quadrature-phase-tracking technique

Abstract

A highly stabilized dynamic displacement measurement system, which employs fiber Bragg gratings to interleave two fiber Michelson interferometers that share the common interferometric optical path, is presented. The phase change in the interferometric signals of the two fiber Michelson interferometers is tracked respectively by maintaining the phase difference in quadrature with two electronic feedback loops. One of the fiber interferometers is used to stabilize the system by the use of an electronic feedback loop to eliminate the influences that result from the environmental disturbances, while the other fiber interferometer is used for the measurement by employing another electronic feedback loop to track the phase change in the interferometric signal. The system is able to measure dynamic displacement and provide a sense of direction of the displacement at the same time. The dynamic displacement with frequencies ranging from 0.1 Hz to 200 Hz and with a maximum amplitude of 60 µm can be measured, and the measurement resolution can reach 10 nm.