Research On Reflected Fiber Distance Sensor With Single Mode Illumination

It is a great technical innovation in fiber phylogeny to put fibers into the use of sensorand detection. As an important branch in fiber sensor field, RIM-FOS (Reflective IntensityModulated Fiber Optic Sensor) is widely used susscussfully in distance, pressure,acceleration, vibration and temperature et al because of their advantages over other fiberdistance sensor, including simpler to construct, less weight, higher bandwidth and immunityto electromagnetic interference et al. The paper firstly makes a review about thedevelopment of RIM-FOS, and completes such studies as follows by summarizing researchachievements of predecessors.First, a theoretical model using approximating the illumination light exiting the singlemode fiber as having a Gaussian intensity profile is established to describe the intensitymodulation performance by taking the reflector angle and shape into consideration.Numerical simulations are made to study the influence of SMF (Single Mode Fiber) NA,SMF mode field diameter, MMF (Multimode Fiber) core diameter, distance between twofibers, offset distance of fiber ends, reflector shape and reflector angle on the performanceof two fiber distance sensor with single mode illumination.Second, to overcome the shortcoming of low sensivitity for the traditional RIM-FOS,the RIM-FOS with inclined illuminating fiber and receiving fiber is proposed and a rigoroustheoretical mode is established to describe the influence of the inclination angle, fiberparameters and structure parameters of RIM-FOS system on the intensity-modulatedcharacteristics of the sensor.Third, the factors that affect the sensor performance are analyzed and a differentialexperiment scheme with compensation effect is proposed. And probe design, optical sourcedrive module, PIN detector drive module, signal processor and collector module et al areintroduced in details.Finally, tests are proceed to obtain the output characteristics of RIM-FOS, including theintensity-modulated characteristics test, reflector angle test, system repeatability andstability, and sensitivities of RIM-FOS, et al.