A compact speckle interferometer for measuring low-amplitude low frequency motion

Contact techniques exist to measure low amplitude low frequency mechanical vibration, however, by mechanically loading the system of interest, they affect the measured results. In this paper, we design a compact non-contact optical fiber speckle interferometer to measure inplane displacements. We implement this under laboratory conditions, and present our calibration results, measuring low-amplitude microvibrations from 0.34 nm to 1.5 μm over a frequency range from 10 Hz to 150 Hz.