Research On Winding Characteristics And Temperature Characteristics Of The Fiber Optic Ring

In the application of fiber optic gyroscope,the change of environment and other factors will cause the drift of output signal and introduce additional phase errors,it seriously affect the precision positioning of the fiber optic gyroscope.As the optical path core device of fiber optic gyroscope,the performance of the fiber optic ring is closely related to the winding process.When the temperature changes,the optical and mechanical properties of the fiber optic ring are changed,which leads to the deterioration of the fiber optic gyroscope.Therefore,research on the measurement and extraction methods of the winding characteristics and temperature characteristics of the fiber optic ring and guide the winding process is one of the means to improve the accuracy and environmental adaptability of the fiber optic gyroscope,and it is urgent to seek a breakthrough.In this thesis,a multi-parameter distributed test system for the fiber optic ring is built,the winding characteristics and temperature characteristics of the fiber optic ring are studied,and the deficiency of multi-parameter measurement and quality evaluation methods for the fiber optic ring is solved.The specific research contents are as follows:1.In order to solve the problem of multi-parameter distributed test of the long-distance fiber optic ring.Firstly,overcome the distributed polarization test technology of the longdistance fiber,and develop the distributed polarization measuring instrument of the longdistance fiber.The measured fiber length can reach more than 10 km,while the polarization crosstalk sensitivity can reach-90 d B,and the dynamic range can reach 80 d B.Secondly,the self-developed distributed polarization measuring instrument is combined with optical timedomain reflectometry measuring instrument,extinction ratio measuring instrument,Brillouin scattering time-domain strain measuring instrument and temperature circulation device to build a multi-parameter distributed test system for the fiber optic ring,so as to realize the multiparameter measurement of the fiber optic ring,and provide a test method for studying the winding characteristics and temperature characteristics of the fiber optic ring.2.In order to evaluate the nonreciprocity of the fiber optic ring when the temperature changes,the distributed polarization characteristics of the fiber optic rings fabricated by different winding processes are measured,and the winding characteristics of the fiber optic rings are studied.On the one hand,the analysis method of distributed polarization crosstalk cross-correlation demodulation is proposed to obtain the changes of linear birefringence under different temperatures,which realizes the quantitative analysis of temperature-induced nonreciprocity of the fiber optic ring.On the other hand,the frequency domain analysis method is used to realize the quantitative analysis of a variety of optical characteristic parameters of the fiber optic ring,and the polarization characteristics and temperature characteristics of the fiber optic ring are comprehensively evaluated.In addition,combined with the time-frequency domain analysis,the temperature characteristics of the fiber optic ring were further analyzed,and the structural parameters and winding defects of the fiber optic ring were evaluated.3.In order to solve the problem of unclear strain distribution of the fiber optic ring when the temperature changes,the relationship between the winding parameters and the strain distribution of the fiber optic ring is studied.Firstly,the length model of the fiber optic ring is established,and the winding characteristics of the layer turn structure of the fiber optic ring are determined.Secondly,the structural mechanics of the fiber optic ring was analyzed,and the theoretical distributed strain model under the temperature change of the fiber optic ring was constructed.The theoretical model was verified by the distributed strain measurement data of the fiber optic ring,and the quantitative relationship between the winding parameters and the strain distribution of the fiber optic ring under the change of temperature was established.In summary,we develop the distributed polarization measuring instrument of the longdistance fiber,and a multi-parameter distributed test system for the fiber optic ring is constructed by combining with commercial optical fiber measuring instruments such as Brillouin scattering time-domain strain measuring instrument.A large number of distributed polarization crosstalk and strain measurement data of the fiber optic ring are tested by using this system.In order to evaluate the process parameters,inner structure and temperature characteristics of the fiber optic ring,we propose methods such as cross-correlation demodulation,time-frequency domain analysis,structural mechanics analysis,and mathematical modeling.Therefore,the winding characteristics and temperature characteristics of the fiber optic ring were analyzed from the distributed polarization crosstalk and strain measurement data.The defects of the fiber optic ring are extracted and the quality of it is evaluated.We provide a test platform and evaluation methods for the research and optimization of winding process of the fiber optic ring.