弹光调制干涉具热动态模型及频率漂移的研究

Study on thermal regime model and frequency drift of a photoelastic modulator interfermeter

为了解决弹光调制干涉具中因高频振动产生的热量引起的谐振频率漂移问题,根据相似与模化理论,建立了弹光调制干涉具热动态模型,得到了弹光调制干涉具中干涉具谐振频率、干涉具温度和外界驱动信号之间的非线性函数关系,并最终推导出了反馈电流和反馈电流相对于驱动电压的相位的关系、干涉具中温度随时间的变化率和谐振频率随时间的变化率方程,以及得出了干涉具热动态模型的频率稳定状态方程。结果表明,根据热反馈机制,必须采用锁相跟踪原理,时刻保持驱动频率与干涉具谐振频率一致,才能保证干涉具工作的稳定性。

In order to solve the problem of the resonant frequency drift caused by the heat produced by high-frequency vibration in a photoelastic modulator interferometer, its thermal regime model was built based on similarity and modeling theory. The nonlinear function relationship among resonant frequency, temperature of the interferometer and outside drive signal was obtained. Finally, the thermal feedback current, the phase relationship between the feedback current and driving voltage, the change rates of the temperature and resonant frequency with time were deduced and the state equation of frequency stability of the interferometer thermal regime model was obtained. Analysis shows that according to thermal feedback mechanism, phase locked tracking theory must be used to maintain drive frequency consistent with resonant frequency of the interferometer all the time so that the interferometer can work stably.