Enhancement of Distributed Fiber Brillouin Scattering Measurement System via Polarization Diversity Scheme and PXI Platform
Date Issued
2010
Date
2010
Author(s)
Hsu, Chin-Hung
Abstract
At present, the maintenance and monitoring of the large-scale structure are dependent on all kinds of sensors, we monitor the conditions of the locations where sensors are laid. However, due to the characteristics of conventional sensors, structural response can only be measured at specific locations. Since it’s very difficult to predict the future damage locations of the structure, the monitoring systems usually fail to reflect the conditions of the structures. Therefore, our lab’s fiber sensor system use the property of distributed sensing for establishing the nervous system of structures, in order to detect structure cracks and avoid accidents.
Our lab have developed Brillouin Optical Correlation Domain Analysis (BOCDA) for distributed strain measurement. BOCDA can achieve distributed strain measurement by controlling a correlation between pump and probe lightwave. In this study, we propose a scheme for polarization diversity to reduce data fluctuation by polarization state change of pump and probe lightwave. First, we used a polarization controller(PC) and adjusted relative polarization state between the pump and probe lightwave to acquire the optimum Brillouin gain. Second, we introduced a polarization switch(PSW) that can generate vertical and horizontal linear polarization state and compensated for the sections that the relative polarization state are not optimum to decrease the measurement errors. And, we use a PXI(PCI eXtensions for Instrumentation) platform to reconstruct our system : replace conventional instruments by PXI modules for lightweight, upgrade transmission rate, cut down the installation cost and apply widely.
Subjects
distributed sensing
polarization diversity
fiber sensor
Type
thesis
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