空间激光干涉仪光程倾斜耦合噪声抑制

Noise suppression of tilt-to-length coupling in space laser interferometer

在"太极计划"中由卫星抖动引起的光程倾斜(tilt-to-length,TTL)耦合噪声是影响激光干涉测量精度的第二大噪声源,为保证测量精度,该噪声要≤±25μm/rad@±300μrad。基于费马原理设计了由双凸透镜组成的成像系统,仿真分析了该成像系统对于TTL耦合噪声的抑制效果,搭建物理实验平台验证了该成像系统抑制TTL耦合噪声的有效性。仿真结果表明:加入双凸透镜成像系统后,TTL耦合噪声≤±10μm/rad@±300μrad;实验结果表明:加入双凸透镜成像系统后,TTL耦合噪声≤±15μm/rad@±300μrad,均满足"太极计划"对光程倾斜耦合噪声抑制水平的要求,且整个干涉光路易于调控、测量精度高。通过搭建物理实验平台验证了TTL耦合噪声的抑制效果,为"太极计划"激光干涉测量奠定了物理实验基础。

In the Taiji mission,the tilt-to-length(TTL)coupling noise caused by satellite jitter is the second largest noise source that affects the accuracy of the laser interferometer. In order to ensure measurement accuracy,it is necessary to suppress this noise to ≤ ±25 μm/rad@±300 μrad. Based on Fermat′s principle,an imaging system composed of biconvex lenses was designed,and the effect of the imaging system on suppressing TTL coupling noise was simulated and analyzed. A physical experiment platform was built to verify the effectiveness of the imaging system in suppressing TTL coupling noise. The simulation results showed that the TTL coupling noise was ≤ ±10 μm/rad@±300 μrad after the biconvex lens imaging system was added;the experimental results showed that the TTL coupling noise was ≤ ±15 μm/rad@ ±300 μrad after the biconvex lens imaging system was added. These results satisfied the requirements of the Taiji mission in terms of the level of TTL coupling noise. Moreover,the entire interference optical path was easy to control,and high measurement accuracy was achieved. The suppression effect of TTL coupling noise was verified by buliding a physical experiment platform,which laid the foundation for physics experiments of the Taiji mission laser interferometer.