Research On High Precision Fiber Optic Gyroscope

Fiber optic gyroscopes based on the Sagnac effect can autonomously measure angular velocity with high precision and real-time performance.Since the first fiber optic gyroscope came out in 1976,it has been widely used in inertial navigation and other fields with the continuous improvement of precision and the rapid development of technology.This research is based on the precise real-time measurement of UT1?Universal Time?of high-precision fiber optic gyroscope.This precise measurement is a new technology application of fiber optic gyroscope,in order to meet the important strategic demand that our country has no independent UT1 measurement system at present.The core of UT1 measurement system is to develop high-precision large-scale fiber optic gyroscope and explore the measurement limit of fiber optic gyroscope,which establishes a solid foundation for high real-time and high-precision measurement of UT1.The main work of this paper is as follows:Firstly,the basic principle of fiber optic gyroscope is introduced,and the influence of optical devices and external environment on the performance of fiber optic gyroscope is analyzed.To meet the needs of the project,an optical path system of interferometric polarization mixing high precision fiber optic gyroscope is designed,and the temperature,magnetic field and vibration of the laboratory are measured.The results show that the laboratory can provide a stable physical environment for the experimental research of the gyroscope.Secondly,for the eigenfrequency measurement of the fiber ring,the two experimental schemes of cross-correlation method and square wave modulation method are designed.The eigenfrequency of the fiber ring with a distance of 1.5 km and a diameter of 11.2 cm is 65.8kHz.The measurement results of the two schemes are consistent.The optimal modulation depth of the system is determined by the signal-to-noise ratio?SNR?.The optimal SNR of the theoretical simulation system is 0.92?,while the experimentally measured optimal SNR is0.9?.Compared with the most sensitive point of the gyroscope at 0.5?,the SNR is obviously improved.Finally,the noise intensity subtraction method is used to suppress the relative intensity noise?RIN?of the light source.In the structure of the simple fiber optic gyroscope,the intensity noise suppression optical path is added,and RIN of the light source is suppressed by subtracting RIN of the light source containing the same component in the two detected optical signals.After RIN of the light source is suppressed,the noise of the gyroscope output signal is significantly reduced.The zero-bias instability reaches 3.6×10^-3°/h,and its random walk is reduced by 32%.Combined with the project tasks undertaken,this paper designs and builds a set of simple fiber-optic gyroscope experimental system with interferometric polarization mixing.By suppressing RIN and optimizing the optical path,the stability of the experimental system enters E^-3°/h,which can meet the requirements of the project.