Light Interference Distributed Fiber-optic Pressure Sensor

Distributed optical fiber sensing technology is a technology using sensing fiber to detect kinds of fields, such as press field, temperature field, electromagnetic field and flow field, distribution along the space and change with the time. Distributed optical fiber press sensor based on polarized modes coupling has relatively high length resolution. This thesis mainly described its operating principle, measuring system and experimental result. In the analysis of operating principle, we deduced the formula of self-interferential intensity and mutual-interferential intensity by modes couping, which is caused by press perturbation. the signals are received by detector after Michelson interferometer. The relation between the press and mutual interferential intensity, the influence of angle between press orientation and fiber's main axis on interferetial intensitys and the method of pressure orientation are analyzed. The factors, which influenced the spatial resolution of the distributed optical fiber pressure sensor, are discussed. The means of improving spatial resolution of the sensor are given too. In the part of experiment system,a white light interferential distributed fiber press sensor by polarized modes coupling is presented. The experimental approaches are described in detail, and a number of measurmental results is obtained too. The results indicate that the output singal of the snsor is linear with the pressure, the mutual interferential intensity is the largest when the angle between pressure orientation and fiber's main axis is about 45°and the spatial resolution of this sensing system is 6cm.