Development of All-Fiber Mach-Zehnder Interferometer and Wireless Sensing Systems for Water-Level, Flow Velocity and Discharge Sensing in Pavement Structures

• Main Authors: WANG, JEN-FU, 王仁甫
• Other Authors: WANG, JIAN-NENG
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/tcpnug

碩士 === 國立雲林科技大學 === 營建工程系 === 106 === A fiber optic interferometer sensor and wireless sensing systems were developed and two fusion-splice different lengths of Mach-Zehnder interferometers (MZIs) were used to measure liquid levels. When the external refractive index is changed, the principle of wavelength shift or transmission change caused by two interferometer in situations of immersing in water to distinguish changes in liquid level. The sensing experiment involves the Arduino sensing system to determine whether a liquid level is touched moisture using the temperature change measured by the DS18B20 temperature sensor. The discharge data measured by the flow sensor were converted into a flow velocity, and the time obtained by LabVIEW software is converted to the flow rates of water level rises and falls. The feasibility testing of the MZIs after fusion-splicing and the Arduino flow sensors and temperature sensors before sensing experiment were conducted in acrylic box. In sensing experiment, two different sensing systems perform the inflow and drainage stages in the acrylic box. From sensing experiments to understand MZIs and Arduino sensor to the response of water level and flow velocity sensing. From the results of the experiment of self-made MZIs, it can be seen that the average spacing of the MZIs interference fringes in each length is inversely proportional to the length (L) of MZIs. It is controlled by the parameters of the fusion splicer, when the length (L) of MZIs is either 2 or 3 cm, it is easy to achieve the standard of interferometer quality. In the optical system inflow and drainage sensing experiments, in the first experiment of the group, WFS-2&3 cm-05, the wavelength shift of the peak 3 in three situations of the drainage stage presented a linear relationship, and the transmission change in three situations of the inflow stage also presented linear relationship. In the second experiment, peak 4 was the best, and the wavelength shifts in three situations of the inflow stage presented linear relationship. In the first experiment of the group, WFS-2&3 cm-01, the wavelength shifts of the peak 4 in three situations of the inflow stage presented a linear relationship. In the second experiment, the amplitude of peak 4 is too small to calculate wavelength shifts, while other peaks have no linear relationship. In the Arduino inflow and drainage sensing experiment, the time changes by temperature sensors were close to the time captured by LabVIEW software. The flow sensor for discharge of the inflow and drainage stages, and the flow velocity can be obtained using LabVIEW software to convert to the rise and fall rates of water level between 5 cm and 30 cm. Thus, the MZIs have preliminary results in sensing water levels and flow velocities and the Arduino system can be used to obtain water level and flow velocity information.