Research On High Precision Optical Fiber Micro Pressure Sensor

Currently it is urgent for a new type of high precision micro pressure sensor which can be implanted into the human body to provide a basis for clinical diagnosis in the field of clinical medicine.It also need to measure the pressure in the industrial production precisely under some harsh industrial environment.In this thesis,an optical fiber micro-pressure sensor based on the low-reflectivity and long-length Fabry-Perot(F-P)cavity structure is proposed.At the same time,combined with the spherical pressure packaging structure,it can realize the high precision micro-pressure sensing without contacted angle measurement error.The main contents of this thesis are provided as follows:1.the theoretical model of F-P cavity of multi-beam interference was deduced and the characters of the transmitted spectrum and reflected spectrum of F-P cavity were analyzed by simulation.It was obtained that the reflection spectrum has a high degree of fineness under the low reflectivity,which lays a theoretical foundation for the proposition of low-reflectivity and long-cavity structure.At the same time,several kinds of cavity length demodulation methods of F-P cavity were analyzed by simulation.2.A broadband low-reflectivity and long-length cavity structure was proposed.The sensitivity curves of different cavities were obtained by simulation,which verified the feasibility of high precision micro-pressure sensing with long-length cavity structure.According to Hooke 's Law and Newton's Second Law of Motion-Force and Acceleration,the frequency response model of the sensor head was established.At the same time,the frequency response curve of the sensor head was obtained by simulation and reducing the thickness of the pressure sensitive end by using the etching process to improve the frequency response of the sensor head was proposed.3.A kind of spherical pressure packaging structure without contacted angle measurement error was proposed.The theoretical model for the pressure conduction of spherical packaging structure was established.The relationship between the geometric dimension of the packaging structure and the spatial angle of the sensor head can perceive as well as the pressure conduction characteristics were obtained by simulation,which verified the feasibility of using the packaging structure to realize the error of contactless angle measurement.4.The micro pressure calibration system was designed and built,the sensitivity and accuracy characteristics were studied.The experimental results show that the relative error is not more than 9.46% in the micro pressure test range of 10 kPa ~ 100 kPa,and the measurement accuracy is ?7kPa.The dynamic characteristic test system based on phase generated carrier(PGC)technology was designed and built,the dynamic characteristics was tested.The test results show that the response frequency of the sensor head can be improved by reducing the quality of the pressure sensitive end,achieved the dynamic pressure response within a certain frequency bandwidth.