Design And Optimization Of The Low Coherence Fiber-optic Displacement Sensor

With the new evolution of science and technology,optical fiber sensing plays a vital rolein detection technology.The expansion of contact joints is one of the important indexes to evaluate the overall performance and safety evaluation of the structure,particularly for bridge structure and large industrial buildings.At present,most of the displacement sensors,were based on the principle of inductance and resistance.Nevertheless,some problems related to their performances existed in these sensors.For example,the poor durability,complex structure,external(such as electromagnetic field)interference effect,etc.In this paper,a joint displacement senor was employed to monitor the bridge box in order to detect the offset interference signal by using a low coherence Michelson's interferometry.Overcoming interference change caused by temperature and environment to make its measurement more precision and stability.Moreover,it was also suitable to monitor the expansion in a online way especially for some key contact bridge engineering structural joints.In low coherence sensor research and design,low coherence multiplexing sensor bears a rapid development,and achieves a good result.For example: due to the rapid development of the high speed mechanical scanning method,the scanning speed of the motor is closely 9times more faster than the former one.Thus,optical fiber interferometer system was greatly reduced their span of one single measurement.So the efficient could be greatly improved.This work was based on the technology of low coherence optical fiber sensor.The displacement sensor was mainly composed of a rod,a reflector,a guide sleeve and a lens rod.The basic knowledge of a low coherence fiber interference was discussed theoretically.The structure,working principle and hardware design of the displacement sensor was introduced.Stability and seismic performance of the displacement sensor monitoring system was carried out.The light source adjustment module was designed based on a Lab VIEW programming module.The analysis of the displacement sensor with the experimental data were verified its reliability and feasibility in solving practical problems.This demonstrated that the designed sensor provided a new potential method for the required displacement monitoring purpose.