Quasi-Distributed Optical Fiber Sensor for Liquid-Level Measurement

A novel fiber-optic liquid level sensor based on a cross-correlation optical time-domain Fresnel reflection technology is proposed and demonstrated. By processing a single-mode fiber (SMF) to create multiple gaps for generating Fresnel reflections, liquids surrounding the SMF modify Fresnel reflection intensity from the multiple gaps and the liquid level can be read by using a cross-correlation technique. We show the sensor for liquid-level remote sensing and its simultaneously measuring level of different liquids located in remote different places. Meanwhile, the sensor is sensitive to refractive index of liquids based on the cross-correlation peak change. The sensor will have many potential applications, because it is intrinsically safe, antielectromagnetic interference, and highly functional with a simple fabrication procedure.