| In the field of biomedicine, miniature sensing technology for invasive pressure measurement has played an important role in diagnosis and treatment. Miniature sensor is also necessary for pressure measurement in high temperature, high pressure, strong electromagnetic interference and corrosive industrial environments. In this dissertation, a kind of miniature extrinsic Fabry-Perot interferometric(EFPI) fiber optic pressure sensor has been developed. Its all-silica structure has good stability for long-term use. In addition, it is cabinet, simple for fabrication and low cost. So this sensor is very suitable for the application in high temperature, high pressure, corrosive and small space environments.Based on the interference theory and varieties of typical structures of EFPI fiber optic sensors, the configuration scheme of the miniature EFPI fiber optic pressure sensor presented in this dissertation has been completed. The miniature sensor head is fabricated with following procedures: A section of silica hollow fiber is bonded at the end of a single-mode fiber;A piece of silica diaphragm is bonded at the opposite end of hollow fiber and processed to the given thickness by cleaving and etching technique. The fiber endface and diaphragm form an etalon cavity. The entire sensor head is only 125μm in diameter. A method on how to determine initial cavity length is proposed. During the experiment the cavity length can be set accurately at a value more than 20μm.The experimental calibration and the temperature dependency test of the miniature pressure sensor are carried out. The experimental results indicate that this miniature EFPI fiber optic pressure sensor has a fairly good performance. In the range from 0 to 25MPa, the linear degree of pressure-cavity length curve is 0.99996 and the sensitivity is 2nm/MPa . The temperature dependence effect of this sensor is small. In the temperature range from 22℃ to 200℃, the temperature sensitivity of the F-P cavity is about 0.03nm/℃ . |
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