Fıber Optıcal Sensor Desıgn For Raılway Safety

Thesis Type: Doctorate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2018


Supervisor: MURAT YÜCEL


Optical fiber communication and security systems have an important place in technological developments. Along with the rapid and prominent development in optical fiber communication technology, optical sensors used in place of electronic sensors are becoming widespread. From an industrial point of view, fiber optic sensors are becoming much more attractive than conventional sensors due to their advantages like immune to electromagnetic interference, not to need additional energy source, resistance to water and corrosion, and their ability to be parallel or serialized. Fiber optic sensors are basically based on optical scattering, but they differ with respect to detection techniques and structures. The study has been realized by performing the fiber Bragg grating (FBG) based sensor system simulations and experiments. For the simulation OptSim 12.0 program has been used. Different applications have been realized for strain and temperature measurement by using developed sensor systems. Railway safety systems that can be developed with these sensor systems have been examined. The simulation results demonstrate that, a wavelength / temperature change of 10 pm / 1 °C was observed due to temperature measurement with FBG. Experimental studies for temperature measurement have used FBGs with different sensitivities and temperature measurements were carried out with a maximum deviation of 0.5 °C. The strain measurement which was held during the experimental study proves that, there is 1.38 pm/με change between wavelength and strain measurement for metal coated FBG. It has been observed that there is a maximum deviation of 2.5% between the calculated theoretical values and the measured values according to the applied force and material properties in the tensile test. In these case studies, a user-friendly and unique graphical user interface has been designed for real-time monitoring of measurements taken with FBG. With the improved signal processing software and the designed interface, it is possible to get stable measurements.