一种监测环氧树脂固化的光纤传感器

A Novel Fiber Optic Sensor for In situ Cure Monitoring of Epoxy Resin

本文研究应用光纤传感技术对环氧树脂固化过程进行实时监测的方法。将光纤的一段包层去掉构成光纤迅衰波折射率传感器，通过测量环氧树脂在固化过程中折射率的变化进行固化监测。由于光纤迅衰波传感器测量的是沿传感区长度方向的平均效果，因而可以在很大的程度上减弱树脂中空隙、杂质等缺陷对测量的影响。通过在光纤传感区一端的光纤端面镀全反射膜形成探针型传感结构，以便于操作。用光时域反射计（ＯＴＤＲ）进行测量，以光纤与光源耦合端面的反射信号作为参考信号对传感信号进行修正，避免了光源光功率的波动和光电探测电路漂移的影响。本文应用射线理论导出光纤固化传感器的理论模型。对Ｅ５１环氧树脂的等温固化过程进行了实时监测实验。

A novel fiber optic sensor based on the principle of Fresnel reflection is presented in order to develop a robust, flexible and low cost cure monitoring sensor. An intrinsic fiber optic sensor (FOX) is made by etching a portion of the cladding of a step index silica optic fiber, which is used to measure the change of the refractive index of the epoxy resin during cure. Because the sensor respones the integrated effects along the sensing region, the influences of the defects in the resin such as voids and impurity can be reduced on a large extent. In order to facilitate the operation, a layer of retroreflectic film is deposited on the distal end of the optic fiber near the sensing region. An optic time domain reflector (OTDR) is employed to measure the reflected signal. The reflected signal from the distal end of the fiber is normalized with respect to the reflected signal detected from the coupling interface to correct the variation in laser optical power and the fluctuation of the sensitivity of the detector the sensor is used to monitor the cure of E51 epoxy resin to test the feasibility of the scheme. The theoretical model of fiber optic cure sensor is alse given in this paper, which is deduced based on the ray theory.