Research On The Key Technology Of Resonator Optic Gyro

ROG(Resonator Optic Gyro) is a high precision inertial devices. It operates on the basic principle that detecting the resonant frequency difference of cavity opposite transmission beam caused by the Sagnac effect to achieve the rotation rate detection.As the core sensitive unit of ROG system, the performance parameters of high quality factor optical micro resonator directly affect the sensitivity of the gyroscope, being critical to the realization of high precision gyro. In order to meet the needs of the inertial measurement system, the structure of the micro resonator is particularly essential.Due to the weak effect of Sagnac, the frequency difference is extremely small. With the influence of factors such as the light path back-scattering noise, non- reciprocity noise,polarization noise, Kerr effect, the ratio of frequency difference output signal to noise is low.Therefore, weak signal detection technology is the key to the gyro signal extraction.In this paper, the key technology of the resonator optic gyro is studied. The specific research contents are listed as follows:(1) Optimizing and designing the two typical micro resonator structure of the fiber ring resonator(FRR) and the silicon-based wedge disk cavity.For FRR, the simulation analysis and testing to verify the mutual restraint relationship between the characteristic parameters were done. For the silicon-based wedge disk cavity,based on the theoretical simulation, optimization of preparation process and structural design was proposed. The experimental verification of the correlation between the disc cavity Q value, DQ product and the sensitivity limit of the diameter D laid the foundation for study of the new chip-level, integrated resonator optic gyro.(2) Based on the non-reciprocity effect of cavity coupling unit, the low refractive index UV glue packaging technology was put forward.Based on the non-reciprocity of disc cavity and the tapered fiber coupling system, a testing system was designed, the test results were analyzed, the best coupling position was obtained. In order to maintain the stability of the coupling structure, robustness and surviving ability under high overload environment, a ultraviolet glue packaging technology was put forward, the micro resonator coupling element integration structure was realized,breaking the routine of traditional micro resonator using high precision position to control and serve platform.(3) Quadratic optimal carrier suppression ratio of back-scattering noise was Analysised and tested, and the method for determining the coefficients of dual optical modulation was put forward.About the resonator fiber optic gyro(Resonator Fiber Optic Gyro, R-FOG), the main optical transmission model of FRR and back-scattering light was improved; by building the back-scattering noise test system of FRR, according to the test results obtained system extreme limit of sensitivity level needed for the 98 dB carrier suppression ratio of the FRR;by using self heterodyne beat frequency, the corresponding relationship curve between the carrier component and the modulation amplitude was obtained under the triangle wave and sine wave phase modulation; through the pulse noise mechanism analysis introduced by triangle wave phase modulation, and the method for determining the coefficients of dual optical modulation was put forward.(4) A full digital open loop detection system for R-FOG was established.Based on FPGA core controller, detection system used the sampling of many steady-state average method to realize the triangle wave modulation of synchronous demodulation, and reduced the effects of impulse noise on signal demodulation. Then by applying CORDIC algorithm in FPGA to achieve a sinusoidal phase modulation and synchronous demodulation; digital frequency lock technique was optimized, controller triggered the process of lock frequency limited in the linear region of the resonant Valley,avoided the risk of false lock.(5) The R-FOG test system was built.When the R-FOG test system was set up, the characteristics parameters of FRR is calculated, and the resonant frequency of the system is tested. The output of R-FOG system under different rotational angular rate was actually calibrated to give a scale factor non-linearity of 4.4‰ within measurement range scale of ?240deg/s, optimal test results of zero bias stability was 0.09 deg ? s-1.