Compact fiber optical interferometer technique to measure picometer displacements in biological piezoelectric materials

Abstract

A simple and robust fiber optical interferometer was developed to non-invasively study the weak piezoelectric effect from thin samples. A biological sample from inter-molt dactyl clubs obtained from the mantis shrimp was used as the test sample. The non-contact technique can measure displacements better than 0.5 picometer for samples subjected to large electric fields. The approach utilizes the phase dependent detection of an oscillating cavity at different frequencies from 0.5 kHz to 2.0 kHz. The piezoelectric constant of the biological samples was calculated from the optical interference fringes and determined to be in the range of 0.3-0.5 pm/V. The noise of 20 fm/Hz 0.5 in the setup is primarily due to thermally associated strains from current flow to the sample electrodes during the measurement.

A Mach–Zehnder Fabry–Perot Hybrid Fibre-Optic Interferometer for a Large Measurement Range Based on the Kalman Filter

“…The extrinsic Fabry-Perot interferometer is suitable for displacement measurements. It has a streamlined structure and is resistant to environmental interference [6]. The intrinsic F-P cavity is placed inside the optical fibre, and depending on the application scenario, such as temperature sensing, pressure sensing, etc., the optical fibre end face is fused to the sensor to form the F-P cavity.…”