Opto-Electronic Engineering, Volume. 51, Issue 2, 230211(2024)

Decoupling study and noise analysis of multi-degree-of-freedom deformation measurement method for space gravitational wave detection telescope

Author Affiliations
• MOE Key Laboratory of TianQin Mission, TianQin Research Center for Gravitational Physics & School of Physics and Astronomy, Frontiers Science Center for TianQin, Gravitational Wave Research Center of CNSA, Sun Yat-sen University (Zhuhai Campus), Zhuhai, Guangdong 519082, China
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Figures & Tables(16)

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 方法 优点 缺点 电学法[20] 电容测量 精度高、稳定性好、测量速度快、反应时间快 无法实现非接触测量，测量范围小 电感测量 精度高、对工作环境要求低 光学法[21] 光杠杆 测量原理简单，易操作，稳定性高 灵敏度低 多路干涉 响应速度快，灵敏度在1 mHz以上占有优势，测量范围更大，角度测量非线性更小 结构复杂，对环境敏感，对结构复杂微 变形的测量和表征能力有限 差分波前 角度测量简单高效 只能进行角度测量且精度受限于探测器
• Table 2. Test the relationship between the rigid body displacement of the mirror and the phase difference received by the photodetector

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Table 2. Test the relationship between the rigid body displacement of the mirror and the phase difference received by the photodetector

 相对位移 相位差 PD1 PD2 PD3 初始位置 0 0 0 沿光轴方向+z平移20 nm 0.47 0.47 0 Rx方向旋转1.7 µrad 0.66 0.47 0.61 垂直光轴方向+y平移20 nm 0 0 0.30
• Table 3. Error sensitivity analysis of the measurement system with multiple degrees of freedom

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Table 3. Error sensitivity analysis of the measurement system with multiple degrees of freedom

 自由度 比值 z dI : S : α = 1 : 0 : 0 Rx dI : S : α= 10000 : 1 : 0 y dI : S : α= 10000 : 1 : 1
• Table 4. Allocation and requirements of optical path noise indicators for the telescope deformation measurement system

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Table 4. Allocation and requirements of optical path noise indicators for the telescope deformation measurement system

 测量系统组成部分 主要噪声源 噪声分配 (nm/Hz1/2@1 mHz) 备注 激光光源 激光频率噪声 3 要求激光频率噪声δf小于4.2×107<Hz/Hz1/2@1 mHz 前端光程耦合噪声 声光调制耦合噪声 1 等效位移噪声<1 nm/Hz1/2@1 mHz 光纤温度耦合噪声 2 光纤温度波动δT≤15 mK/Hz1/2@1 mHz 集成光学 器件平台 温度位移耦合噪声 8 温度位移耦合系数dS/dT=70 nm/K，测试环境温度波动δT≤15 mK/Hz1/2@1 mHz 振动位移耦合噪声 2 振动位移耦合系数dS/dx=0.3×10−3 m/m，测试环境振动波动δX≤1×10−3 m/s /Hz1/2@1 mHz 空气折射率噪声 2 温度波动δT≤15 mK/Hz1/2@1 mHz 偏振噪声 2 等效位移噪声<2 nm/Hz1/2@1 mHz 杂散光噪声 3 控制杂散光强度相较于主光束低于−20 dB 信号采集 数据处理 探测器耦合噪声 1 相对强度噪声需低于−100 dB/Hz@1 mHz 相位读取噪声 0.01 要求相位计等效位移本底噪声是0.01 nm/Hz1/2@1 mHz 测量系统总体噪声 10
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Jian Luo, Jie Song, Sijun Fang, Fanle Kong, Yong Yan. Decoupling study and noise analysis of multi-degree-of-freedom deformation measurement method for space gravitational wave detection telescope[J]. Opto-Electronic Engineering, 2024, 51(2): 230211