Vibration Sensititity Analysis Of The Ultra-Stable Optical Cavity

In this paper, we show the relationship between deformations of the ultra-stable optical cavity and its cavity length change, which is universal. The relation can be utilized to analyze the cavity length variation of cavities of different shapes and dimensions and the most important is that we can use it to calculate the variation taking the error of installation and machining error into consideration.The vibration sensitivity of the horizontal optical cavity is analyzed with FEA, and vibration sensitivities of the vertical and horizontal directions are given quantitatively. Vibration sensitivity optimization in X, Y and Z directions is executed and in the optimal position sensitivities in the three directions are all≤10-10/g. Different evaluate conditions may give out different results which comes from mesh size, contact condition, restraint condition and so on in FEA. These variances are analyzed quantitatively.To measure the vibration sensitivity of the ultra-stable optical cavity and compare calculating results with experimental data, a small shaking platform is designed. The platform can vibrate in three directions independently and when it is drive along one direction, couplings of acceleration in other two directions is smaller than10%. Simple, small and easy to manufacture are its advantages.Temperature fluctuations can lead to expansion and contraction of cavity materials caused by heat and cold, which will change cavity length, so temperature control is necessary to the ultra-stable optical cavity. The control is performed indirection by stabilizing the temperature of the vacuum. The long term temperature drift (24hours)and short term fluctuation are1mK and5mK respectively.Allan variance which has a high request to the method of frequency measuring is the major term indicating the frequency stability. Therefore measuring schematics of several different counters are analyzed in this thesis which provides a guidance for choosing a suitable counter. Beating is the major approach to measure vibration sensitivity and real-time display and saving of beating data and Allan variance can be achieved with LabVIEW programming.