Design on a Common-path Precision Fiber Optic Displacement Sensor

An optic fiber displacement sensor has been developed based on the reflective light intensity-modulation, a concept have wide range of application in fiber optic displacement sensors designing. Its structure is different from the conventional reflective intensity-modulated fiber bundle with only one fiber as the emitting fiber (EF) and Receiving fiber. The principle is similar to the reflective light intensity bundle that the distance measured by the light intensity reflected from a reflective object. As both the emitting light and the reflective light travel through the same optical path, the sensor probe can be very thin, less than a millimeter or smaller. Because of the system is very simple, it has demonstrated substantially improved immunity against environmental perturbations over the conventional fiber bundle. Our simulation results show that the received light intensity agrees well with its mathematical model. The sensor measurement range is about 2mm, and the resolution is 5 mu m. The influence of numerical aperture, the fiber core diameter and the plane reflectance have been studied and the results shows that the sensor have good preferable application foreground in the engineering fields.