为了解决传统抖动分析方法在TMT(Thirty Meter Telescope,30m望远镜)三镜轴承上的局限性,提出了利用Gabor变换作为抖动性质及信号特性的评价方法。介绍了多加速度计的位置分布及连接方式,详细说明了加速度计在俯仰轴及方位轴上抖动信号...为了解决传统抖动分析方法在TMT(Thirty Meter Telescope,30m望远镜)三镜轴承上的局限性,提出了利用Gabor变换作为抖动性质及信号特性的评价方法。介绍了多加速度计的位置分布及连接方式,详细说明了加速度计在俯仰轴及方位轴上抖动信号的测试过程。在抖动信号数据处理中比较了时间序列法和周期图法的不足,提出了Gabor变换的新方法,Gabor变换可以截取任意时间段上的频谱信息的性质,在时-频域上分析信号的特征,使抖动分析更加真实可靠。最终在某2m级望远镜轴承上做了抖动测量实验,从实验结果可以看到2s内的频率特性曲线,接近0 Hz的低频扰动比较敏感,50 Hz噪声扰动一直存在,470Hz的高频信号时续时断。当轴承顺时针转动时,1 s时有很明显的噪声信号;轴承反向转动时,1.5s^2s时噪声信号突出,降噪后低频噪声依然存在,但高阶频率被激励,保证了信号的真实性.Gabor变换的信号处理方法对于今后大型光电望远镜轴承抖动检测的研究具有一定借鉴意义。展开更多
Giant Steerable Science Mirror( GSSM) is the tertiary mirror of the Thirty Meter Telescope( TMT).To evaluate the performance of the GSSM under the mechanical vibration,the Normalized Point Source Sensitivity( PSSn) is...Giant Steerable Science Mirror( GSSM) is the tertiary mirror of the Thirty Meter Telescope( TMT).To evaluate the performance of the GSSM under the mechanical vibration,the Normalized Point Source Sensitivity( PSSn) is used to understand and characterize the optical performance degradation. First and foremost,the definition of the PSSn is shown and the calculation procedure of the PSSn at the work condition where the telescope aberration is much smaller than seeing is presented to reveal the relationship between PSSn and seeing.Then,the optical degradation due to vibration is achieved by the two methods: one is the statistics moment for the arbitrary froms of vibration and other one is spectrum method for wind load. After the theoretical presence,the simulation is processed. The multi-axis-accelerometers are used to achieve the motion of the mirror. After integrated to displacement signal,the measured signal is applied to the mathematical model of the GSSM and the optical performance degradation under certain mechanical vibration can be achieved. The PSSN flows from 0.996 to 0.994 under some dynamic vibration. And then,the wind load is applied to the mathematical model using spectrum method with the PSSN flows from 0.996 to 0.991. This paper can help the system engineers to predict the performance of the GSSM in various work condition. What is more,PSSn is able to be combined just by simple multiplication,so the optical performance degradation can be easily co-considered with other error sources.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.11403022)
文摘Giant Steerable Science Mirror( GSSM) is the tertiary mirror of the Thirty Meter Telescope( TMT).To evaluate the performance of the GSSM under the mechanical vibration,the Normalized Point Source Sensitivity( PSSn) is used to understand and characterize the optical performance degradation. First and foremost,the definition of the PSSn is shown and the calculation procedure of the PSSn at the work condition where the telescope aberration is much smaller than seeing is presented to reveal the relationship between PSSn and seeing.Then,the optical degradation due to vibration is achieved by the two methods: one is the statistics moment for the arbitrary froms of vibration and other one is spectrum method for wind load. After the theoretical presence,the simulation is processed. The multi-axis-accelerometers are used to achieve the motion of the mirror. After integrated to displacement signal,the measured signal is applied to the mathematical model of the GSSM and the optical performance degradation under certain mechanical vibration can be achieved. The PSSN flows from 0.996 to 0.994 under some dynamic vibration. And then,the wind load is applied to the mathematical model using spectrum method with the PSSN flows from 0.996 to 0.991. This paper can help the system engineers to predict the performance of the GSSM in various work condition. What is more,PSSn is able to be combined just by simple multiplication,so the optical performance degradation can be easily co-considered with other error sources.
