Design and production of segment mirrors for the large-sized telescopes of the Cherenkov Telescope Array
Design and production of segment mirrors for the large-sized telescopes of the Cherenkov Telescope Array
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切伦科夫望远镜阵列大型望远镜分段镜的设计和生产
DOI：
10.1117/12.2562111
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Vovk Ievgen
中科院分区：
文献类型：
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作者：
Inada Tomohiro;Fukami Satoshi;Noda Koji;Chikawa Michiyuki;Kagaya Mika;Katagiri Hideaki;Mazin Daniel;Obara Koutaro;Okumura Akira;Saito Takayuki;Teshima Masahiro;Yamamoto Tokonatsu;Yoshida Tatsuo;Vovk Ievgen
CTA（切伦科夫望远镜阵列）是下一代地基伽马射线天文台的一个项目。CTA将通过3种不同直径的望远镜覆盖20 GeV和300 TeV的宽能量范围。CTA的大型望远镜（LST）旨在覆盖最低能量范围。我们正在为将在西班牙拉帕尔马建造的4艘LST建造镜子。CTA-LST的抛物面主镜直径为23 m，焦距为28 m。主镜由198个分段镜组成。总有效反射面积约为370平方米。每个镜子都有一个1.51米并排大小的六边形形状。它具有夹层结构，由铝蜂窝（60 mm厚）和两个玻璃表面（2.7 mm）组成，总重量约为47 kg。我们使用溅射沉积技术在表面涂覆5层。涂层保护表面长期运行，如10年在外面，反射率下降小于1%一年。反射镜的反射率在400 nm处达到约92%，并且其分辨率为直径0.5 mrad，其中包含由反射镜反射的80%的光。基于冷崩的生产工艺使其生产稳定。我们报告的部分反射镜的设计和生产约950六角形2平方米的镜子，以实现4 LST的光学系统的抛物线形状。
CTA (Cherenkov Telescope Array) is a project for the next generation of the ground-based gamma-ray observatory. CTA will cover a wide energy range, 20 GeV and 300 TeV, by 3 types of the telescopes whose diameters are different. The Large-Sized Telescopes (LSTs) of the CTA are designed to cover the lowest energy range. We are working on mirrors for 4 LSTs which will be built at La Palma, Spain. The parabolic primary mirror of CTA-LST is 23 m diameter and its focal length is 28 m. The primary mirror consists of 198 segmented mirrors. Total effective reflective area is about 370 m2. Each mirror has a hexagonal shape of 1.51 m side-by-side size. It has a sandwich structure which consists of aluminum honeycomb (60 mm thickness) and two glass surfaces (2.7 mm) and the total weight is about 47 kg. We used a sputtering deposition technique to coat in the surface with 5 layer. The coated layers protect the surface for long operation such as 10 years at outside with a reflectance degradation of less than 1 % a year. The reflectance of the mirror reaches about 92 % at 400 nm and its resolution is 0.5 mrad in diameter that contains the 80 % light reflected by the mirror. The production technique based on cold slumping gave us the stable its production. We report on the design of the segment mirror and the production of about 950 hexagonal 2 m2 mirrors to achieve the parabolic shape of the optical system for 4 LSTs.