发表机构
Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut); Leibniz Universität Hannover（马克斯·普朗克引力物理研究所（阿尔伯特·爱因斯坦研究所）; 汉诺威莱布尼茨大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出并验证了激光干涉测量中光束角度锁定环路的理论与实验框架，通过差分波前传感和线性控制模型实现高精度共轴对准，实验指向稳定性优于10 urad/√Hz，并展示了无需硬件修改的环路优化策略。
AI 中文摘要
在激光干涉测量中，保持精确的光束共轴对准至关重要，尤其是在星间任务中，角度失准会引入倾斜-长度耦合噪声，并存在链路完全中断的风险。本工作提出了光束角度锁定环路的全面理论与实验框架，该环路用于维持两束干涉光束之间的共轴对准。微小的角度失准通过差分波前传感信号检测，该信号用作反馈控制的误差信号。我们建立了一个详细的线性控制模型，包含角度探测器、数字滤波器、比例-积分-双积分伺服、数模转换器以及光束转向机构。利用环路传递函数，我们建立了噪声传播模型，量化了各个组件对环路外和环路内角度误差的贡献。分析结果通过基于应答器的干涉链路进行了实验验证，该链路跨越两个光学平台，并使用六足平台模拟航天器姿态抖动。测得的传递函数和共轴对准性能与理论预测吻合良好，在0.2 mHz至1 Hz频率范围内，指向稳定性优于10 urad/√Hz。此外，我们展示了一种环路优化策略，通过调节伺服增益，在目标频带内最小化角度失准，而无需硬件修改。这一经过验证的框架为激光干涉测量中主动光束对准的设计与优化提供了可靠的架构。
英文摘要
Maintaining precise beam coalignment is essential in laser interferometry, particularly for interspacecraft missions where angular misalignments introduce tilt-to-length coupling noise and risk complete link failure. This work presents a comprehensive theoretical and experimental framework for the beam angle-locked loop, which maintains coalignment between two interfering beams. Minute angular misalignments are detected via differential wavefront-sensing signals, which are used as the error signal for feedback control. A detailed linear control model incorporating an angle detector, a digital filter, a proportional-integral-double-integral servo, a digital-to-analog converter, and a beam-steering mechanism is developed. Using loop transfer functions, we establish a noise-propagation model that quantifies the contributions of individual components to both out-of-loop and in-loop angle errors. The analytical results are experimentally validated using a transponder-based interferometric link spanning two optical benches, with a hexapod simulating spacecraft attitude jitter. The measured transfer functions and coalignment performance agree well with theoretical predictions, yielding a pointing stability better than 10 urad$/\sqrt{\text{Hz}}$ between 0.2 mHz and 1 Hz. Furthermore, a loop-optimization strategy is demonstrated to minimize angle misalignment within a target frequency band by tuning the servo gain, without requiring hardware modifications. This validated framework provides a reliable architecture for designing and optimizing active beam alignment in laser interferometry.
Comments14 pages,12 figures
