An improved fiber optic pressure and temperature sensor for downhole application

摘要

We report on the fabrication of a high pressure extrinsic Fabry-Perot interferometric (EFPI) fiber optic sensor for downhole applications by using a mechanical transducer. The mechanical transducer has been used for increasing the pressure sensitivity and the possibility of installation of the sensor downhole. The pressure-temperature cross-sensitivity (PTCS) problem has been solved by replacing the reflecting fiber with a metal microwire in the EFPI sensor. In this way the PTCS coefficient of the sensor was decreased from 47.25 psi deg C~(-1) to 7 psi deg C~(-1). By using a new EFPI design, a temperature sensor was fabricated. Further improvement in the pressure and temperature sensor has been done by developing fabrication technique and signal processing.