双圈同轴式光纤位移传感器的输出特性

为了利用双圈同轴式光纤位移传感器准确测得旋转机械中滑动轴承的润滑膜厚度,分析了反射面形状以及润滑油折射率对双圈同轴式光纤位移传感器输出特性的影响.利用几何光学分析方法,建立了反射面为球面时的光纤传感器输出函数的数学模型,分析了润滑油折射率对光纤入射角的影响.结果表明:当传播介质的折射率大于1时,光纤最大入射角减小;当反射面曲率半径减小时,传感器的灵敏度会降低;与光线在空气中传播相比,传播介质为润滑油时,随着传播介质折射率的增大,传感器的灵敏度降低.因此,在利用双圈同轴位移传感器进行滑动轴承的润滑膜厚度监测时,必须对传感器进行重新标定.

Output Characteristics of the Displacement Sensor with Two-Circle Reflective Coaxial Fiber

The effects of the reflective surface configuration and the refractive index of lubricating oil on the characteristics of the displacement sensor of two-circle reflective coaxial fiber,which is used to measure the thickness of the lubricating oil film,is analyzed.An output function of the fiber sensor with spherical reflective surface is gained and the effect of refractive index of lubricating oil on the maximum incidence angle is analyzed by geometrical optics.The refractive index of the lubricating oil decreases the maximum incidence angle of fibers.The simulation and the experiment indicate that the sensibility of sensors decreases when the reflector changed from flat to curved and in the propagation medium varying from gas into lubricating oil,which leads to the necessity of recalibration when the sensors are applied to monitoring the thickness of the lubricating oil film.