Coating noise is a consistently significant source of noise in high-precision gravitational wave measurements. In this paper, a model that quantifies the relationship between temperature noise and the optical path variation is proposed to analyze the thermo-optic noise of optical coating. There are two types of temperature-dependent noise—the traditional equilibrium thermal noise and the position noise introduced by the overall temperature fluctuation in the telescope load—that need to be considered for space gravitational wave detection satellites. In the current off-axis quad-mirror design, the incident angle of light from each mirror is very different, and the maximum incident angle reaches nearly 45°. The optical path noise of all-dielectric reflective coating will be more significant under the large incident angle. Metal reflective coating can effectively suppress the optical path noise caused by low-frequency temperature fluctuation, making them a viable alternative for space gravitational wave detectors. This paper provides a valuable reference for the selection of reflective coatings in space-based gravitational wave telescopes from the perspective of coating noise.

中文翻译：

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空间引力波探测望远镜涂层中热光噪声和非平衡噪声的计算方法


涂层噪声是高精度引力波测量中始终重要的噪声源。本文提出了一个量化温度噪声与光程变化之间关系的模型，用于分析光学镀膜的热光噪声。空间引力波探测卫星需要考虑两种类型的温度相关噪声——传统的平衡热噪声和望远镜负载中整体温度波动引入的位置噪声。在目前的离轴四镜设计中，来自每个镜子的光线入射角差异很大，最大入射角达到近 45°。全介质反射涂层的光路噪声在大入射角下会更加显著。金属反射涂层可以有效抑制低频温度波动引起的光路噪声，使其成为空间引力波探测器的可行替代方案。本文从镀膜噪声角度为天基引力波望远镜反射镀膜的选择提供了有价值的参考。