Oblique end face coupling optical fiber sensor for point fuel level measurement

A new implementation of point level sensor fabricated using the oblique multimode silica fibers is proposed and demonstrated. Based on Fresnel reflection, all the incident lights are reflected back by the oblique sensor header when the sensor is in the air, and a proportion of lights are leaked when the sensor is in the liquid. In order to get the maximum reflected light intensity modulation, the calculation model of the sensor is proposed to optimize the oblique angle. The simulation of light path and light intensity detection by means of finite element analysis demonstrates that the sensor is evidently sensitive to liquid and the reflected lights can be coupled into the receiving fibers, which makes easy detection. Gradient and continuous level experiments indicate that the sensor has the measurement accuracy of ±0.6 mm and good stability.