Self-adaptive Cavity Length Control System For Ring Laser Gyro

The ring laser gyro is the ideal angular sensor for the inertial system. Compareted to the conventional spinning gyro, it is characteristic of high sensitivity,high accuracy and large dynamic range. The system controling the cavity length of the ring laser is very important, it has a large influence on the bias stability and the magnetic sensitivity of the ring laser. This paper designs the self-adaptive cavity length control system by using TMS320F2812, a kind of DSP with high performance. It aims at satisfying the need of engineering application of the ring laser.Firstly, the principle of the ring laser is introduced. The principle of laser frequency stabilization in differerntial ring laser is expatiated. The disadvantages of the path length control system which uses the different intensities of the left and right circularly polarized light and the advantages of dithering path length control system are dicussed. A self-adaptive path length control arithmetic is demonstrated by using a parabola approximate the intesity of the light in the vicinity of the mode peak.Secondly, a path length control system is designed by using2812, including the section of digital analogy conversion and analogy digital conversion. The mathematics model of the path length control system is made.The transfer function of the system is analyzed. We presented the system’s open-loop and closed-loop transfer function. A simulation of self-apapt path length control system based on hill-climbing method is made, and the result of the simulation is analyzed.Thirdly, the DSP control code compiled software is chosen to be CCS. The system achieves the path length control system using hill-climbing method. Further more, the DSP control code is compiled aimed at achieving the function of self-adaptive path length control.In the end, the experimental system is introduced and an experiment of cavity length control using hill-climbing method is made.The results of the experiment prove that the long-time frequency instability is less than0.61MHz. The experiment of self-adaptive path length controling is also made. The results prove that the system can aviod the influence of the change of the circuit amplification and PZT sensitivity, and that the system can improve the stability of the ring laser gyro.