Design and performance of fiber optic pressure cell based on polarimetric sensing

摘要

Abstract: paper we propose replacing a widely used but often difficult and cumbersome technique of hydraulic evaluation of stress in concrete materials with a new fiber-optic measurement device, which has all inherent advantages of fiber-optic sensors. The sensing element of the device consists of a highly birefringent (HB) polarization-maintaining optical fiber. The stress inside it induced by external pressure modulates the polarization state of the output light signal at the detection end of the system. The all-fiber instrumentation system of the sensor consists of a semiconductor pigtailed laser, input and output HB optical fibers, an analyzer and a computer-controlled synchronous detection system. A specially designed leadthrough integrated with the sensor head allowed us to insert the sensor inside a pressure pad filled with oil or alternatively with mercury. For calibration purposes, the pressure cell was placed inside a large pressure chamber designed to simulate the real environment. Characterization of the device for hysteresis, selectivity and sensitivity was performed for pressures up to 70 bar and for ambient temperatures. The described sensor is simple, cost-effective, safe in explosive environments and well adapted for stress monitoring in the large-scale structures.!8