Interferometric dynamic displacement measurement using phase-modulated light along with stepwise control of operation point

摘要

We propose the fiber-based interferometric measurement of tens-of-nanometer-scale dynamic displacement that uses phase-modulated reference light with stepwise control of the operation point of modulation (OPM). It requires neither the pre-adjustment of the OPM nor feedback control for the path-length difference of the interferometer. Quantitative evaluation of the system is performed by using a phase modulator as a sample to simulate mechanical vibration. The dynamic displacement for 100-kHz vibration with an amplitude of 19 nm is measured even when the fiber interferometer is intentionally perturbed, which confirms the effectiveness of the proposed method. (C) 2018 The Japan Society of Applied Physics