Q&A(Quantum Electrodynamics test and search for Axion)實驗是一個以探測真空雙折射(vacuum birefringence)效應為目標之實驗，其主要由懸吊8米的Fabry-Perot干涉儀與轉動永久磁鐵及一組偏振檢測儀組成，利用光在Fabry-Perot來回反射加大真空雙折射效應。除了加大真空雙折射效應外，降低環境噪音也是一個重要課題，它可以避免真空雙折射效應被環境背景值掩蓋。此篇論文主要講述地振噪音的消除-交叉擺減振系統，真空雙折射實驗是量測偏振的變化，鏡片如果受到地震的晃動，將對實驗造成很大的影響，因此減振系統非常需要。我們將講述交叉擺結構與原理計算，並在實驗中測到交叉擺兩個方向共振頻率分別為0.15 Hz及0.17 Hz。

The Q&A (Quantum Electrodynamics test and search for Axion) experiment aims to explore the vacuum birefringence effect. It mainly consists of an 8-meter suspended Fabry-Perot interferometer, a rotating permanent magnet, and a set of polarization detectors. The back-and-forth reflection of light in the Fabry-Perot enhances the vacuum birefringence effect. In addition to amplifying the vacuum birefringence effect, reducing environmental noise is also a crucial concern to prevent the effect from being masked by background values. This paper primarily discusses the elimination of ground vibration noise through an X pendulum damping system. The vacuum birefringence experiment measures changes in polarization. If the mirrors experience shaking due to ground vibration, it can significantly impact the experiment. Therefore, a damping system is essential. We will discuss the cross-pendulum structure and principle calculations.the resonance measured in this experiment are 0.15 Hz and 0.17 Hz respectively

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