## 1 Introduction
also proposed a 6-DOF isolation platform based on the quasi-zero-stiffness isolator to suppress disturbances above 10 Hz [28]. [PERSON] et al. proposed a high-damping viscoelastic material to reduce high-frequency disturbance of the reaction wheel on the camera [29]. However, traditional passive vibration isolation systems struggle to suppress low-frequency disturbances. Although the incorporation of active control can broaden the suppression bandwidth, as demonstrated by [PERSON] et al. with a coarse-precision parallel vibration isolation pointing platform for disturbances ranging from 2 to 20 Hz, such systems often become overly complex, contradicting the trend toward lightweight designs for high-precision optical loads [30; 31]. Conversely, integrating a fast steering mirror (FSM) to compensate for residual LOS jitter under low-frequency conditions has garnered increasing favor among researchers [7; 32; 33]. For instance, [PERSON] et al. studied a two-stage vibration isolation precision pointing system consisting of a Stewart platform and an FSM capable of suppressing micro-vibrations above 1 Hz [7]. Taking the large size of the high-precision space optical payload (HPSOP) in our study into account, a two-stage image stabilization system, composed of three bipod vibration isolation legs (BVILs) and a decoupled FSM, is introduced in this paper to achieve high-precision pointing accuracy. In light of the aforementioned analysis, there are several obstacles to the micro-vibration test and image stabilization of the HPSOPs. First, due to the adjustment errors caused by the non-automatic gravity unloading, traditional micro-vibration test platforms cannot meet the higher precision measurement requirements of the micro-vibration on HPSOPs. Second, because of the nonlinear coupling and amplification, the linear superposition of independent disturbances cannot reflect the actual impact of composite micro-vibration, such as CMGs and cryocoolers. Last, owing to the wide frequency band cover of micro-vibration, it is difficult to achieve sub-micro-radian pointing accuracy by suppressing the disturbances appearing in the low frequency and mid-high frequency at the same time. To address the above problems, this paper proposes a micro-vibration test platform equipped with AQZSSD gravity unloading devices, and a two-stage image stabilization system incorporated with three BVILs and a decoupled FSM, bridging the gap between the concept and engineering implementation of high-precision micro-vibration measurement and sub-micro-radian LOS stabilization. This study is organized as follows. First, the detailed composition and experimental process of the micro-vibration test platform are introduced in Section 2. Then, the quasi-zero stiffness characteristic of an AQZSSD and the principle of calculating LOS jitter angles are discussed in Section 3. The disturbance suppression in the mid-high frequency and LOS jitter angle compensation in the low frequency of the two-stage image stabilization system are proved in Section 4. Further, experimental results with the analysis and discussion, are presented in Section 5. Finally, a conclusion is drawn in Section 6.