Cryogenic silicon carbide mirrors for infrared astronomical telescopes: lessons learnt from AKARI for SPICA
Cryogenic silicon carbide mirrors for infrared astronomical telescopes: lessons learnt from AKARI for SPICA
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DOI：
10.1117/12.2026662
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发表时间：
2013-09
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影响因子：
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通讯作者：
T. Onaka;H. Kaneda;M. Kawada;K. Enya;T. Nakagawa
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文献类型：
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作者：
T. Onaka;H. Kaneda;M. Kawada;K. Enya;T. Nakagawa
碳化硅（SiC）具有良好的导热性、较高的刚度和相对较低的比密度，这些都有利于在低温下工作的望远镜的应用。2006年2月，日本首个天文红外太空任务AKARI发射升空，完成了中远红外6个波段的第二代全天巡天，使用了特制碳化硅制成的700毫米低温望远镜。它是一种由轻质多孔芯和致密化学气相沉积（CVD）涂层组成的三明治型SiC，以降低比密度并便于加工，以达到所需的表面形状精度。用干涉仪对160mm样品镜的测量结果表明，AKARI SiC反射镜在低温下（~6K）具有良好的热稳定性，而紧凑设计的反射镜支架成为AKARI望远镜波前误差的主要来源。利用AKARI望远镜的发展和欧空局的赫歇尔望远镜的遗产，我们正在计划下一个红外空间任务SPICA（空间红外望远镜用于宇宙学和天体物理学），一个3.2米的冷却望远镜，参与欧空局使用sic基材料。本文总结了AKARI SiC望远镜的发展历程，并从SiC作为低温空间红外望远镜反射镜材料的角度介绍了SPICA望远镜的发展情况。
Silicon carbide (SiC) has good thermal conductivity, high stiffness, and a relatively low specific density, all of which are advantageous to the application to telescopes operating at cryogenic temperatures. The first Japanese astronomical infrared space mission AKARI, which was launched in 2006 February and completed the second generation all-sky survey at 6 bands from mid- to far-infrared, employed a 700mm cryogenic telescope made of specially developed SiC. It was a sandwich-type of SiC composed of a lightweight porous core and a dense chemical vapor deposition (CVD) coat to decrease the specific density and facilitate machining for achieving the required surface figure accuracy. Measurements with an interferometer of 160-mm sample mirrors demonstrated that the AKARI mirror SiC had good thermal stability down to cryogenic temperatures (~6K), while the mirror support of the compact design became the primary source of the wave-front errors of the AKARI telescope. Taking the advantage of the heritage of the AKARI telescope development as well as ESA’s Herschel telescope, we are planning the next infrared space mission SPICA (Space Infrared Telescope for Cosmology and Astrophysics) of a 3.2m cooled telescope in participation of ESA using SiC-based materials. In this presentation, we summarize the development of AKARI SiC telescope and present the development activities of the SPICA telescope from the point of view of SiC being as the mirror material for cryogenic space infrared telescopes.