A new optical fiber sensor with improved strain sensitivity based on distributed optical fiber sensing technique

摘要

In general, macro-strain is an effective index for health monitoring of civil infrastructures, which can reveal the unforeseen damage accumulation. However, it is difficult to acquire precise strain distribution with existing fully-distributed optical fiber sensing techniques. Based on the distributed optical fiber strain sensing technique of pulse-prepump Brillouin Optical Time Domain Analysis (PPP-BOTDA), a new optical fiber sensor with improved strain sensitivity (OFSISS) is proposed to enhance the precision of macro-strain measurements. The most advantage of the OFSISS sensor is that it can markedly reduce the measurement error of strain data with a proper designed magnified coefficient. The OFSISS has also good designability and durability according to detailed sensing requirements. Results of uniaxial tensile experiment show not only the high accuracy and precision of the OFSISS but also an important fact that the measured magnified coefficients of the manufactured OFSISSs with a recoating process agree well with the designed values. The bending experiment of using a steel beam illustrates that the linearity and reliability of macro-strain measurement from the OFSISS are good enough for the application in actual macro-strain monitoring and structural deformation monitoring.