Observational astronomy has sought better telescopes with higher resolution from its beginning. This needs ever-larger mirrors with stable, high-precision surfaces. The extremely low-expansion glass ceramic ZERODUR® has enabled such mirrors for more than 50 years with significant improvements in size and quality since then. We provide a survey of the progress achieved in the last 15 years. Equally important as the thermal expansion coefficient CTE is its homogeneity. The CTE variation in 4-m mirror blanks lies below 5 ppb / K in radial and axial directions on large and short scales. Improved measurement capabilities allow reduced bias, which in the past made variations look greater than they were. Isotropy and uniformity of ZERODUR are outstanding. A method for lifetime calculation increases reliability considerably with respect to mechanical loads. The production and metrology capability and capacity are greatly extended. Surface figure and texture of large blanks allow starting directly with polishing. Filigree structures with up to 90% weight reduction are well-suited for space mirrors. The progress with low thermal expansion and its measurement, the insensitivity of ZERODUR against ionizing radiation in space, and outstanding application examples are presented in the first part of our review.

中文翻译：

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玻璃陶瓷 ZERODUR ^®：更接近于零热膨胀：综述，第 2 部分

观测天文学从一开始就寻求分辨率更高的更好的望远镜。这需要具有稳定、高精度表面的更大反射镜。50 多年来，极低膨胀玻璃陶瓷 ZERODUR® 使此类反射镜的尺寸和质量得到了显着改进。我们对过去 15 年中取得的进展进行了调查。与热膨胀系数 CTE 同等重要的是其均匀性。在大尺度和短尺度上，4 米反射镜坯料的 CTE 变化在径向和轴向上低于 5 ppb / K。改进的测量能力可以减少偏差，这在过去会使变化看起来比实际更大。ZERODUR 的各向同性和均匀性非常出色。一种寿命计算方法可显着提高机械负载的可靠性。生产和计量能力和产能大大扩展。大毛坯的表面形状和纹理允许直接从抛光开始。重量减轻高达 90% 的细丝结构非常适合空间反射镜。我们评论的第一部分介绍了低热膨胀及其测量的进展、ZERODUR 对空间电离辐射的不敏感性以及突出的应用实例。