A torsion balance as a weak-force testbed for novel optical inertial sensors

Abstract

Torsion balances (TBs) are versatile instruments known for their ability to measure tiny forces and accelerations with high precision. We are currently commissioning a new TB facility to support the development and testing of novel optical inertial sensor units for future gravity-related space missions. Here, we report on the status of our apparatus and present first sensitivity curves that demonstrate acceleration and torque sensitivities of 5 ⋅ 10 − 11 m s − 2 and 1 ⋅ 10 − 12 N m H z − 1 at frequencies around 4 m H z , respectively. Capacitive sensors and optical levers measure the dynamics of the system with a displacement sensitivity of down to 9 ⋅ 10 − 10 m H z − 1 for the former and 2 ⋅ 10 − 11 m H z − 1 for the latter. Combining the readout of the suspended inertial member (IM) with environmental sensor signals, the system is characterized, and limiting noise sources are identified. We find that, in particular, the coupling of ambient seismic motion is limiting over a broad frequency range and show that due to its high susceptibility to ground motion, our TB is also a promising platform for exploring ground motion sensing in multiple degrees of freedom. Future upgrades will focus on mitigating seismic noise by controlling the torsion fiber suspension point using piezoelectric actuators and the integration of precision interferometric readout of the IM. These improvements will further increase the sensitivity towards the thermal noise limit which constrains the performance to 1 ⋅ 10 − 13 m s − 2 H z − 1

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将扭力天平作为新型光学惯性传感器的弱力试验台

扭力天平（TB）是一种多功能仪器，能够高精度地测量微小的力和加速度。我们目前正在调试一台新的扭力天平设备，以支持未来重力相关太空任务中新型光学惯性传感器单元的开发和测试。在此，我们报告了我们设备的状况，并首次展示了灵敏度曲线，该曲线显示在 4 m H z 左右的频率下，加速度和扭矩灵敏度分别为 5 ⋅ 10 - 11 m s - 2 和 1 ⋅ 10 - 12 N m H z - 1。电容传感器和光学杠杆测量系统的动态，前者的位移灵敏度低至 9 ⋅ 10 - 10 m H z - 1，后者的位移灵敏度低至 2 ⋅ 10 - 11 m H z - 1。结合悬浮惯性部件（IM）的读数和环境传感器信号，对系统进行了表征，并确定了极限噪声源。我们发现，环境地震运动的耦合在很宽的频率范围内尤其具有限制性，并表明由于其对地面运动的高敏感性，我们的 TB 也是探索多自由度地面运动传感的一个很有前途的平台。未来的升级将侧重于通过使用压电致动器控制扭转纤维悬挂点来减轻地震噪声，以及集成 IM 的精密干涉读数。

本文章由计算机程序翻译，如有差异，请以英文原文为准。