Q&A实验中的椭偏噪声谱、悬挂系统传递函数测量和闭环控制
仪器与探测器
2007-05-23 v2
摘要
Q&A实验旨在探测量子电动力学预测的真空双折射,主要由一个悬挂的3.5米法布里-珀罗腔、一个旋转的永磁偶极子磁铁和一个椭偏仪组成。2.3特斯拉的磁铁可以以高达10转/秒的速度旋转,在旋转频率的两倍处引入椭偏信号。X摆在其主共振频率0.3赫兹以上对地震噪声具有良好的隔离比。目前,椭偏噪声随频率降低,从5赫兹时的1*10^{-5}弧度赫兹^{-1/2},到20赫兹时的2*10^{-6}弧度赫兹^{-1/2},再到40赫兹时的5*10^{-7}弧度赫兹^{-1/2}。噪声谱的形状表明,可以通过进一步减少腔镜之间的运动来改进。从偏航运动对准控制的初步结果可以看出,一些由腔镜偏航运动引起的峰被抑制了。在本文中,我们首先给出Q&A实验的示意图,然后介绍复合X摆-双摆悬挂系统传递函数的测量。进行了闭环控制以验证所测传递函数的有效性。最后给出了有无偏航对准控制的椭偏噪声谱以及最新的改进。
引用
@article{arxiv.physics/0508176,
title = {Ellipsometry noise spectrum, suspension transfer function measurement and closed-loop control of the suspension system in the Q & A experiment},
author = {Sheng-Jui Chen and Hsien-Hao Mei and Wei-Tou Ni},
journal= {arXiv preprint arXiv:physics/0508176},
year = {2007}
}
备注
7 pages, 5 figures, presented in 6th Edoardo Amaldi Conference on Gravitational Waves, June 2005, Okinawa Japan and submitted to Journal of Physics: Conference Series. Some modifications are made according to the referee's comments: mainly to explain the relation between the displacement of cavity mirror and the ellipticity noise spectrum