Fiber optic distributed sensing techniques with high spatial resolution and high performance for smart materials, structures and communication networks.

点击翻译按钮获取中文摘要

Research subjects originally scheduled in this project have enough been done, and some new subjects have also been added and performed. As for the first subject "Fiber optic distributed strain sensing technique by use of stimulated Brillouin scattering generated locally along the fiber," dynamic strain sensing function has been introduced. The sampling rate obtained is 57Hz, which is 10,000 time faster than conventional time domain technologies. In vibration measurement using a building model, multiple points, simultaneous and dynamic strain sensing has been done for the first time. Clack in concrete with sub-mm width has also been measured for the first time, utilizing cm-order spatial resolution of this technique. This technique is only one that can measure distributed strain along a fiber with cm-order spatial resolution and several tens of Hz sampling-rate. These functions are creating new diagnostic algorithm for materials and structures. A way for simplifying the system, a scheme … More for elongating the measurement range, a way for measuring simultaneously strain and temperature, and a scheme for realizing quite a high spatial resolution have also been proposed and experimented. As for the second subject "Fiber optic distributed lateral stress measurement by synthesis of optical coherence function," the spatial resolution has been improved as about 40 times to be 20cm. A simplified system has also been realized. As for the third subject "Diagnostic system for fiber to the home networks," measurement range has been improved. At the end of 5km length fiber, reflectivity distribution has been measured with about 10cm spatial resolution and 1km measurement range. As for the forth subject "Related sensing technologies," a system for multiplexing FBG's with the same Bragg wavelength has newly been developed by the use of synthesis of optical coherence function technique (SOCF). Sampling rate of 100Hz and random access capability has been realized. A FBG multiplexing system using a fiber laser with multiple lasing wavelengths, scheme for controlling characteristics of EDF dynamic grating by SOCF, a system for measuring vibration distribution along a fiber, and so on, have also been proposed and developed. Through this research project, novel techniques of fiber optic nerve systems for smart materials, structures and communication networks have been successfully developed. Less