POF Displacement Sensors
This chapter discusses mathematical analysis based on both ray and wave optics is developed in order to predict the response function of the sensor. This analysis will be useful to understand how different parameters acting on the sensor affect its response. Plastic optical fibers (POFs) are specially suited for displacement sensors due to their facility for handling, large diameter, numerical aperture, and flexibility. The chapter describes the influence that several parameters, such as fiber radius asymmetry, separation between transmitting and receiving fibers, angle of the fiber tip and between fibers, and tilting and roughness of the reflecting surface, have on the sensor response. It explains an application of POF displacement sensors (POFDS) for the measurement of the tip clearance of an aeronautical turbine. The analysis and response of POFDS can be addressed from two different points of view: geometrical and wave-like.