基于F-P腔的干涉/强度调制型光纤温度传感器

Fiber Optic Temperature Sensor Based on F-P Cavity Interferometric/Intensity Modulation Mechanism

介绍了一种基于非本征F-P腔的干涉/强度调制型光纤温度传感器.宽谱光源发光二极管(LED)发出的光经过2×2耦合器C1传给F-P传感头,传感头返回光信号再次经过耦合器C1及C2后分成两路,一路直接传给光电探测器D1,另一路经过窄带滤光片再传给D2,光信号经光电转换及放大后由计算机采集处理.给出了采用不同谱宽的两路光信号进行自补偿运算和温度测量的理论模型,并简单分析了影响这一温度传感器长期稳定性的原因.实验中利用Levenberg-Marquardt非线性拟合得到与理论模型符合很好的温度定标曲线.该传感器在20～200℃量程内,温度变化最小分辨率达到0.1℃,长期测量精度达到±0.2℃.

A fiber optic temperature sensor based on extrinsic Fabry-Perot (F-P) cavity interferometric/intensity modulation mechanism is described. The light from a light-emitting diode (LED) is coupled into a 2 × 2 multimode fiber coupler C1 and propagates to the F-P sensor head. The light reflected from the F-P cavity is recoupled into C1, and then through another fiber coupler C2 the light is divided into two beams. One propagates to optoelcctronic detector D1 and another through narrow filter propagates to detector D2. The two signals are transported to the computer through the optoelectronic conversion and amplifier circuit. A theoretical model for the temperature calculation and self-compensation has been worked out, which gives out the compensated intensity expression on the F-P cavity length, spectral width of the light source and band pass filter. The temperature calibration curve was obtained by fitting the experiment data to the theoretical model with Levenberg-Marquardt algorithm. A minimum temperature resolution of 0.1°C and long term accuracy of ±0.2°C were obtained over a temperature measurement range of 20∼200°C.