自适应量程的光频域反射光纤传感互相关算法

Cross-Correlation Algorithm of Optical Frequency Domain Reflectometry Sensing System Based on Adapted Range

光频域反射(OFDR)技术是一种基于频域分析的光学检测技术,通过互相关算法可以实现高空间分辨率的分布式光纤温度、应变传感,在航天器、飞行器等的结构健康监测中具有重要的作用。普通互相关运算在OFDR光纤温度、应变传感解调算法中存在测量量程较小和计算量较大的问题,限制了OFDR的大量程应用和解调速率的提高。为此,提出一种自适应量程的互相关算法,该算法不仅有效增大了OFDR的温度、应变测量量程,同时提高了系统的解调效率。实验验证了算法的可行性,并测试了算法的运行时间,结果表明该算法可使解调效率提高为原来的2.25倍;实际测量了20~500℃的大量程温度曲线,给出三次方曲线拟合,拟合残差<0.1℃;在±3000με的范围内进行应变测试,测试误差≤5με。

Optical frequency domain reflectometry(OFDR) is an optical detection technique based on frequency-domain analysis. It can achieve high-spatial-resolution distributed fiber temperature/strain sensing through a cross-correlation algorithm and has great application prospects in the structural health monitoring of spacecraft, flight vehicles, etc. Common cross-correlation algorithms have problems of small range and large amounts of computation in OFDR fiber temperature and strain sensing demodulation, which limits the large-range application of OFDR and the improvement of the demodulation rate. For this reason, a cross-correlation algorithm based on an adapted range was proposed. The algorithm not only improves the range of temperature and strain measurement but also enhances the demodulation efficiency of the system. Experimental results show the feasibility and efficiency of the proposed algorithm. The demodulation efficiency was increased by 2.25 times. The large-range temperature curve from 20 ℃ to 500 ℃ was measured, and the residual error of cubic curve fitting was less than 0.1 ℃. The test error was no greater than 5 με in the strain range of ±3000 με.