Research Of FBG Sensor With Temperature Self-compensation Based On Rhombus Structure

Fiber Bragg grating(FBG)make good candidates because of its excellent performance,such as light weight,small size,insulation,anti-electromagnetic interference,corrosion resistance,high temperature resistance and long transmission distance.The center wavelength of FBG is affected by temperature and strain as sensing unit,thus margin of deviation may appear in the detection of non-temperature parameters and the accuracy of sensor will be affected seriously.In order to solve this problem,a variety of temperature compensation methods are proposed,but there are some shortcomings and the compensation is less effective.For example,there is non-equal amplitude compensation and phase lag using the method of double-gate temperature compensation,the effect of temperature compensation will be weakened in the detection process.So it is urgent to study new FBG temperature compensation method.In this paper,a single FBG temperature self-compensating structure named rhombus structure is analyzed from three aspects: material,structure and device and the self-compensation characteristic of temperature is proposed.Meanwhile,the temperature self-compensation and sensing model of rhombus structure is proposed.Two kinds of rhombus structure sensors are manufactured,the reliability and applicability of temperature self-compensation performance have been verified through theoretical analysis and experimental test.The experimental results show that the FBG with rhombus structure has good self-compensation performance and good sensing performance.The main research contents and achievement of this paper can be summarized as follows:(1)The present situation of the existing FBG sensor temperature compensation methods are compared and analyzed,a theoretical model of temperature compensation is proposed based on the principle of fiber Bragg grating sensing and the deformation principle of rhombus structure.(2)The matching relation between the rhombus structure material and the size parameter and the material under test is obtained by the analysis of the temperature self-compensation theory mode base on rhombus structure sensing mechanism.Thetemperature self-compensation of rhombus structure was verified by ANSYS thermodynamic module that provides some theoretical guidance for the material and size selection after the rhombus structure sensor.(3)In this paper,the influence of rhombus structure parameters on the characteristics of the sensor is studied which infers the theoretical formula of the sensor sensitivity,the rhombus structure sensing model is constructed and is verified by finite element model.(4)Two kinds of fiber grating rhombus sensors are developed by analyzing the structure of rhombus sensor based on the temperature compensation model and sensor model of rhombus structure.(5)The two kinds of sensors are packaged and tested.The reliability and applicability of the temperature self-compensation of rhombus shaped structure are verified by static and dynamic temperature test.At the same time,performance test of sensor show that fiber grating sensor has good sensing characteristics based on the rhombus structure;the test results are compared with the theoretical values,and the causes of errors are analyzed.