恒星干涉仪延迟线系统地面随机振动响应分析

研究地面随机微振动对恒星干涉仪关键部件-光学延迟线系统性能的影响。利用美国蓝氏(Lansmont)集团生产的SAVER 3X型三轴振动仪实测地面随机振动信号,以输出的G加速度功率谱密度为激励,运用Workbench有限元分析软件计算该结构系统的随机振动响应;根据抛物镜面节点数据拟合出抛物镜面的Zernike多项式系数、抛物镜刚体平移量和抛物镜面PV和RMS值;将Zernike多项式系数导入光学系统中分析光学延迟线系统光学性能;最后利用ELCOWAT 3000电子自准直仪测量抛物镜刚体平移量,分析实际测量结果和计算理论结果偏差。分析计算结果与实验数据最大偏差7.6%,计算抛物镜面形RMS值为9.6 nm,PV值为46.1 nm,波前差为0.043λ。目前的光学延迟线的地面振动满足光学延迟线系统的稳定性要求。使用动态光学性能标准分析判断微振动对系统光学性能的影响程度,为恒星干涉仪其他子系统优化设计和隔振补偿措施提供参考。

Random ground vibration response of the optical delay line system of a stellar interferometer

The stability problem of an optical delay line system caused by random ground vibration was concerned. The random ground vibration signal and G acceleration power spectral density(PSD) were measured and the random vibration response of the mount was analyzed with the PSD module of Workbench finite element software. The Zernike polynomial coefficient,the translation of rigid body,the root mean square(RMS) value and peak-valley (PV) value of the parabolic reflector were calculated by fitting the nodes data. Introducing the Zernike polynomial coefficient into the optical system,the optical performance of the optical delay line system was analyzed. The rigid body translation of the parabolic reflector was measured by ELCOWAT 3000 Electronic Autocollimators. The analysis results show that the largest analytical errors with respect to the simulation and experiment are 7.6%. The RMS value is 9.6 nm,and PV value is  46.1 nm. The error of wavefront is 0.043λ. The actual vibration level of the installation base meets the stability requirement of the optical delay line system. The research on the relationship between the optical performance and the random vibration provides important reference to the optimal design and vibration isolation of other optical systems of stellar interferometers. 