Influence of light source on the sensitivity of a Polarization Maintaining Fiber Loop Mirror vibration sensor

Abstract

Wavelength or light intensity demodulation method for a polarization maintaining fiber loop mirror (PM-FLM) sensor is not only expensive but also unsuitable for vibration monitoring. This paper studies the voltage demodulation principle and explores theoretically the influence of light source on the sensitivity. Then a PM-FLM sensor is applied to vibration monitoring. A low-power narrow-band light source reflected from FBG and a high-power laser light source are used respectively as input. The time domain voltage signals of vibration from a photo-detector are collected by a data acquisition card and converted via a fast Fourier transform algorithm. The experimental result shows that a PM-FLM sensor using a high-power narrow-band light source as input has a higher sensitivity to vibration than the one using a low-power narrow-band light source. In practical application, we can choose a high-power narrow-band light source as input to improve the sensitivity to vibration.

A Method of Structural Vibration Deformation Monitoring Based on FBG Strainmeter and Accelerometer Array

“…For example, bridges with hundreds of meters long spans may produce maximum deflections of up to several tens of centimeters subject to static and dynamic loads. A 400meter building may exhibit a top floor deflection of up to 1 meter under strong windy conditions [1] . The submarine pipeline would gradually lose the support of the foundation soil and become suspended under the action of ocean currents, with its vibration frequency gradually decreases as the span increases, which is very likely to produce eddy excitation vibration to occur under the excitation of ocean currents, resulting in extremely hazardous.…”