White Light Interferometric Fiber-optic Fabry-perot Cavity Sensor

Fiber-optic Fabry-Perot sensor is a kind of high precision interferometric fiber-optic sensor, so this kind of sensor has a bright future. This sensor can be classified into 3 kinds of sensors by their demodulation device. These are intensity modulation/demodulation fiber-optic Fabry-Perot sensor, phasemodulation/demodulation fiber-optic Fabry-Perot sensor and white-light interferometer modulation/demodulation fiber-optic Fabry-Perot sensor. The later two kinds of sensors are white-light interferometric fiber-optic Fabry-Perot sensor because of their broad-spectrum light source. White-light interferometric fiber-optic Fabry-Perot sensor solved the problem that the conventional fiber-optic Fabry-Perot sensor only measure relatively, so it can be buried into material structure to monitor the inner state of material structure. Therefore this kind of sensor is best sensor for smart structure.At first, we studied the theory of light interferometry, multi-light interfeormetry and white-light interferometry. Then we analysed the working principle of white-light interferometric fiber-optic Fabry-Perot sensor, and get two kinds of ways for demodulation: directive(phase) and inderective(white-light interferometer) modulation/demodulation ways.Secondly, we discussed key technics of manufacture of fiber-optic Fabry-Perot sensing head. We get the ways to decide the primitive length of fiber-optic Fabry-Perot cavity by use of theory, and designed two systems to measure the length of fiber-optic Fabry-Perot cavity. We get the film reflectivity of fiber-optic Fabry-Perot cavity by calculation, and designed a experimental device to observe white-light interferometry. Then we introduced the manufacture process of of fiber-optic Fabry-Perot sensing head in detail.At last, we introduced the design of demodulation device of white-light interferometer modulation/demodulation fiber-optic Fabry-Perot sensor. We provide the ways to improve the property of sensor. We performed a experiment to test the capability of our sensor to strain gauge, and applied our sensor into study on carbon fiber material temperature property.