Design Of Frequency Stabilization Circuit In The Rotary North-Finder Based On Ring Laser Gyroscope

In the system of rotary North-Finder based on Ring Laser Gyroscope, differential gyros is the key instrument. Insuring the precision of the differential gyros is the precondition of the North-Finder's precise north-finding. As the photoelectric preamplifier and frequency stabilization are the most important parts of the peripheral circuit of the differential gyros, the circuit design of photoelectric preamplifier and frequency stabilization shows important position in the system design of the North-Finder.Firstly, the basic fundamental of the differential gyros and its frequency stabilization is introduced. On this basis, two kinds of laser frequency stabilization scheme based on DC and AC are educed, and the strong points and shortcomings of the two kinds of scheme are discussed respectively. Combining with the RLG's small working dynamic range, the conclusion that the scheme based on AC is the best choice is educed.Secondly, each part and its corresponding transfer function of the system made up of photoelectric preamplifier and frequency stabilization is analyzed, and the system's open-loop and closed-loop transfer functions are presented, The closed-loop control system for frequency stabilization is simulated by the tool of Matlab. According to the simulation result, some circuit parameters are optimized to ensure the system's stability and response speed.In the end, the photoelectric preamplifier's output Signal Noise Ratio and the laser frequency stability are tested. The experimental result shows that the photoelectric preamplifier's output SNR achieves 33.3dB, and the laser frequency instability is less than 0.33MHz. The whole circuits work fine and stably, which shows that they meet the demand of the North-Finder system.