Temperature and distance-dependent errors in a dual-cavity fibre Fabry-Perot interferometer for vibration analysis

Fabry-Perot interferometers developed for vibrometric applications have various advantages. However, they are not free from environmentally induced errors. In this paper, we attempt to investigate the temperature and distance-dependent errors in displacement measurement obtained using a fibre Fabry-Perot vibration sensor. By varying the temperature of the laser diode via a temperature controller module, the wavelength variations as a function of temperature in the emitted spectrum were measured. These shifts were then converted into the desired displacement values and compared to those under typical operating conditions (at 25degC). In another experimental setup, the distance between the sensing arm and the target was varied from 72 -1172 mm and the measured displacement amplitudes analysed, giving a possible range of displacements. A commercial displacement sensor has been used as reference for comparison in the distance-to-target study, resulting in a maximum percentage displacement error of 0.668 %.