Research On Opeartion Properties Of Dual-Longitudinal Mode Prism Laser Gyro

The total reflection prism laser gyro(TRPLG)adopts total reflection prism(TRP)to form a closed ring optical path,which has a lot of advantages,such as the small locking range,the simple structure,the high reliability and the long service time.Due to the backscattering and the inhomogeneous loss in ring cavity,the lock-in effect becomes one of the biggest error sources of laser gyro.In recent years,resarch have shown that when the TRPLG in the state of two longitudinal modes oscillating,the lock-in range reduces,and is obviously smaller than the celestial component of the earth’s rotation speed when the two longitudinal modes locates in the special position of the gain curve,and this is so called ’self-biassing’ phenomenon.Based on this phenomenon,it is possible to establish a new bias technology,which has no moving parts in the cavity,and is not sensitivity to magnetic,and has no over-locking error,so it is an ideal frequency bias scheme.For the self-biassing phenomenon existed in the dual-longitudinal mode laser gyroscope,based on semi-classical theory of laser,the behaviors of the amplitude and frequency of ring laser with dual longitudinal mode oscillation are studied.Some physical effects related to the intensity are discussed.These works lay a theoretical foundation for revealing the phenomenon of selfbiassing and engineering of self-biassing gyro.The main contents and results of this paper are as follows:1 Based on the semiclassical theory of laser,the theory of dual-longitudinal mode ring laser under the two-isotope system condition is established,from the wave equation of ring laser and the polarization process of gain medium.In the derivation,the general case of non-Doppler limit is considered.2 Based on the Doppler effect of ring laser and Bennett model,the intermode coupling effects of ring laser with two longitudinal modes oscillating is analyzed.On this basis,the intensity tuning curve of the dual-longitudinal mode ring laser is calculated.3 A platform for detecting the intensity tuning curve of the dual-longitudinal mode ring laser was established.A 0.47m prism ring cavity is used and the gain gas with the ratio of He:Ne=15:1 and Ne20:Ne22=0.53:0.47 is filled.The intensity tuning curve of the ring laser was obtained,and the simulations are verified.4 The interference spots of different high-order transverse modes are studied by using laser mode theory.In the experiment,the cat’s eye laser is used to generate different order high-order transverse mode interference fields,and on this basis,the morphology characteristics of different order transverse modes interference spots of laser gyro are studied.Combined with the analysis of the optical path movement characteristics of the prism ring resonator under the condition of temperature variation,the mechanism of the optical spot disorder when the accuracy of the laser gyro is abnormal in the actual temperature variation experiment is studied.