Fiber Optic Accelerometers And Bending Sensors Based On PGC

Since Internet of Things was listed as one of the five emerging strategic industries written into the government work report, the researches of sensors set off a boom in the country. Because of high sensitivity, anti-electromagnetic interference capability, dynamic range, waterproof, corrosion resistance, light weight, small size and low loss, fiber sensors become one of hot researches.In this thesis, a novel fiber optic accelerometer based on Fabry-Perot interfemetetry and an optical fiber bending sensor based on Michelson interferometry are proposed.The fiber optic accelerometer utilizes a silicon micro-mirror mounted on a mesh spring elastic structure and a fiber facet to form a Fabry-Perot cavity which can generate optical interference signals as a function of acceleration. Phase generated carrier technology(PGC) was adopted to modulate the interference signals to obtain a high resolution of phase signals. Performance measurement of prototype shows it has a sensitivity of 63.2 rad/g below a resonance frequency of 160 Hz and a resolution of 4μg with a dynamic range near 108. And an optical fiber bending sensor obtains a sensitivity of 43.96 rad/m-1 and a resolution of 0.004 m-1, by utilizing PGC to modulate the Michelson interference signals generated by a fiber ribbon which is affixed onto an elastic structure,.From the study of the basic theory of fiber sensors, this thesis mainly completes contents as followings:1. Concentrated on the understanding and study of the basic concept of fiber sensors, including the structure of fiber, the theory of light transmit in fiber and the devices commonly used in fiber sensors. The main parameters ofsensors were also described. All of these provided the theoretical basis of the design of sensors, as well as prototypes testing and evaluation.2. Based on the definition of accelerometers, analyzed both the advantages and disadvantages of various accelerometers. Summarized the trends of accelerometers.3. Described the design and principle of deferent interference fiber optic accelerometers in detail. Proposed a fiber optic accelerometer based on Faby-Perot interfermetry. Design the inertial sensing system of the fiber optic accelerometer and did Strain analysis of the elastic structure of the inertial sensing system by CosmosWorks. Studied the ways to realize phase generated carrier modulation and demodulation of this accelerometer.4. Introduced how to use CNC(Computer Numerical Control) precision engraving technology to fabricate stainless steel mesh and how to implement PGC algorithm. Took tests of the accelerometer, and the results show it achieves both in high accuracy and large dynamic range.5. Described the basic theory and application of several kinds optical fiber bending sensor, and proposed an optical fiber bending sensor based on Michelson interferometry. Introduced the fabrication of the fiber ribbon and fiber index matching liquid cavity, which are the critical components in the optical bending sensor.6. Took experimental tests of the optical fiber bending sensor, measurement results show it has a resolution of 0.004 m-1 which is higher than most of bending sensors.