用于FBG检测的OLCR系统实用化技术

Practical FBG Characterization System Based on OLCR

光纤布拉格光栅(FBG)反射谱特性的变化是传感检测的关键,光学低相干反射(OLCR)技术是获得FBG反射谱特性的重要方法。构建了一套基于Michelson干涉光路结构的OLCR-FBG检测系统,给出了系统工作原理和实现方式,研究中提出系统实现的关键是干涉微弱信号采集、均匀分布采样、离散数据处理过程。实验测试了非平衡探测结构和平衡探测结构的系统信号,普通电动平移台驱动和高精度气浮平移台驱动的系统信号。实验结果表明,平衡探测结构提高了微弱干涉信号信噪比;低振动噪声的气浮平移台能实现均匀分布采样,避免反射谱被淹没;通过数据处理,能从干涉信号快速解调出FBG反射光谱,其Bragg波长重复性达到4 pm。

The key to the sensing application of the FBG is the demodulation of the reflectance spectrum, and OLCR technology is an important method to obtain the characteristic of FBG reflectance spectrum. Based on Michelson interference optical path, a set of OLCR-FBG detection system has been established, hence, the operating principle and implementation mode of the system are expounded. In the study, we propose that the pivotal issues in the system realization are the acquisition of weak interference signal, uniform sampling and discrete data processing. In the experiments, the interference signals of balance detection and unbalance detection, together with the signals of general translation stage and air-bone translation stage are detected. Results show that the SNRof interference signal is improved by balance detection structure; Low-noise air-bone translation stage makes great contribution to uniform sampling by avoiding the reflectance spectrum signals being covered by the noise; Through data processing, FBG reflectance spectrum can be quickly demodulated from interference signal, and repeatability of the Bragg wavelength is 4 pm.