基于菲涅耳反射的准分布式光纤温度传感器

基于菲涅耳反射原理和光时域反射(OTDR)技术,提出了一种新型的、结构简单的准分布式光纤温度传感器.传感器由两个端面抛光的光纤对接构成,并在两端面间隙中填充温敏材料.传感器周围温度变化改变温敏材料的折射率,从而引起菲涅耳反射强度的变化.将三个传感头串联,利用OTDR探测各传感器菲涅耳反射的微弱变化实现温度传感和传感器定位.在-30～80℃范围内,随着温度升高,该系统各个传感头的菲涅耳反射强度单调增大,且温度传感特性具有良好的重复性,同时具有极低的附加损耗.

A Quasi-Distributed Optical Fiber Temperature Sensor Based on Fresnel Reflection

Based on the principle of Fresnel reflection and the optical time-domain reflectometry (OTDR) techniques, a quasi-distributed optical fiber temperature sensor which can achieve accurate temperature measurement is presented. The sensor head is made of two face-to-face single-mode optical fibers whose end surfaces have been polished. The gap betwen two fibers is filled with a temperature-sensitivity material. The temperature variation causes the refractive index of the filling material to change, and then the intensity of Fresnel reflection will be changed. A sensing scheme with three sensor heads in series is investigated in experiment. The slight changes in Fresnel reflection intensity are detected by OTDR, with which the temperature sensing characteristics are studied. The experimental results show that the Fresnel reflectivity increases monotonically when the temperature varies from -30 ℃ to 80 ℃. The sensor heads have good repeatability and low insertion loss.