Fiber Fabry-Perot Strain Gauge Based On The Technology Of Wavelength Analysis For Bridge Health Monitoring

Fabry-Perot sensing is a new strain measurement technology with the development of fiber technology at the end of 1980,Extrinsic Fabry-Perot interferometer(EFPI) had become a hot point in the area of "smart structure" in foreign countries since it has the advantage of simple structure and low sensitivity towards temperature. Domestic research on Fabry-Perot sensor is still at the laboratory stage, and there is little report of the application on the smart structure. Supported by NSFC, Academician Fund of Chongqing Municipality and Postdoctoral Science Fund of China, the application study on EFPI was carried on by the Department of Opto-Electronic Engineering of Chongqing University based on the first generation fiber F-P gauge. Results is followed:1. Many kinds of EFPI sensors and their demodulation methods were compared. A comparative simple scheme, wavelength modulated/demodulated EFPI strain sensing system, was adopted and been used in the new generation fiber optic strain-sensing gauge.2. Accuracy of wavelength modulated/demodulated EFPI system was carefully investigated based on the theory of error. Two kinds of improved algorithms (peak-to-peak algorithm and multipeak algorithm) were put forward to reduce this error.3. A new demodulated algorithm in gap domain was introduced and the characters were analyzed. This way had been applied in the new generation fiber optic strain-sensing instrument. 4. Multiplexed sensor technology was studied, a new way was applied to realized series connection and parallel connection multiplex.5. New generation fiber optic strain-sensing gauge was applied to realize long period strain healthy monitoring of DaFoSi bridge in the Yangtze River.