Active vibration isolation of ultra-stable optical reference cavity of space optical clock

• DOI: 10.1016/j.ast.2021.106633
• Publication Date: 2021-03-18T17:24:24Z
• Authors: Keda He; Qing Li; Lei Liu; Hongjie Yang
• Keywords: Voice coil; Active Vibration Control; Isolation

Abstract Space optical clocks with frequency instability better than 1 × 10 − 15 are increasingly demanded for PNT (positioning, navigation, and timing) and space physical science. Inevitably, the micro-vibration level in the order of micro-g (μg) is required for ultra-stable optical reference cavity of space optical clocks. The realization of such a strict micro-vibration requirement over broadband frequencies is still technically challenging under complex space disturbances in the order of milli-g (mg). This paper thus proposes a multi-degree of freedom (DOF) active vibration isolation approach for the ultra-stable optical reference cavity to satisfy the stringent micro-vibration requirement. Non-contact voice coil actuators are designed as the driving unit of active vibration isolation. The robust vibration isolation controller is presented considering the control uncertainty caused by the voice coil clearance and the low frequency drift of accelerometers. The loop shaping technology is used to avoid the current drift and achieve high accuracy vibration isolation over the designed bandwidth. The active vibration isolation experimental platform is further developed, and the experimental results validate the effectiveness of the designed multi-DOF active vibration isolation scheme.