Modern space-based telescopes operating in the terahertz (THz) spectral range require highly reflecting and cryogenically cooled optics ensuring extremely low noise. The idea of using high-temperature superconductor YBa2Cu3O7-δ as a telescope's mirror coating for providing low dissipation and high reflectivity of the surface for the subTHz frequency band has been explored. We are presenting here some results of measurements of the reflection losses in YBa2Cu3O7-δ at cryogenic and room temperatures (4.2–300 K) in the frequency band 0.166–0.23 THz. High-accuracy measurements of the absolute value of reflectivity have been performed with the help of the resonance technique. The measured reflection losses in the given frequency band were below 1%. For the same frequency range, these values are well above the reflection losses in normal metals such as copper or aluminum, which are normally used to cover mirrors of telescopes. We, therefore, conclude that the use of high-Tc superconductors YBa2Cu3O7-δ as a highly reflecting coating for the THz telescope's mirror is not advisable.

中文翻译：

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YBa2Cu3O7-σ 在低温下的太赫兹反射率

在太赫兹 (THz) 光谱范围内运行的现代天基望远镜需要高度反射和低温冷却的光学元件，以确保极低的噪音。已经探索了使用高温超导体 YBa2Cu3O7-δ 作为望远镜镜面涂层的想法，为亚太赫兹频段提供低耗散和高反射率的表面。我们在此展示了在 0.166-0.23 THz 频带中低温和室温 (4.2-300 K) 下 YBa2Cu3O7-δ 反射损耗的一些测量结果。在共振技术的帮助下，已经对反射率的绝对值进行了高精度测量。在给定频带内测得的反射损耗低于 1%。对于相同的频率范围，这些值远高于通常用于覆盖望远镜反射镜的铜或铝等普通金属的反射损失。因此，我们得出结论，使用高温超导体 YBa2Cu3O7-δ 作为太赫兹望远镜反射镜的高反射涂层是不可取的。