Fiber Optic Pressure Sensor with Self-Compensation Capability for Harsh Environment Applications

Abstract

A novel fiber optic pressure sensor system with self compensation capability for harsh environment applications is reported. The system compensates for the fluctuation of source power and the variation of fiber losses by self-referencing the two channel outputs of a fiber optic extrinsic Fabry-Perot interfrometric (EFPI} sensor probe. A novel sensor fabrication system based on the controlled thermal bonding method is also described. For the first time, high-performance fiber optic EFPI sensor probes can be fabricated in a controlled fashion with excel lent mechanical strength and temperature stability to survive and operate in the high-pressure and high-temperature coexisting harsh environment. Using a single-mode fiber sensor probe and the prototype signal processing unit, we demonstrate pressure measurement up to 8400 psi and achieved resolution of 0.005% (2a= 0.4 psi) at atmospheric pressure, repeatability of ± 0.15% (± 13 psi), and 25-h stability of 0.09% (7 psi). The system also shows excellent remote operation capability when tested by separating the sensor probe from its signal-processing unit at a distance of 6.4 km.