Large, ultra-thin, lightweight,carbon-fibre adaptive mirrors for ELTs

当今世界上使用的最大光学望远镜的主镜直径可达10米。主镜的大小基本上决定了望远镜能探测到的物体的微弱程度。目前正在进行开发下一代望远镜的工作。这些望远镜的主镜直径为30-60米，通常被称为超大型望远镜(ELT)。30米的望远镜将能够探测和研究比10米望远镜暗9倍的物体，因此将能够更远地回顾早期宇宙，并回答一些关于星系形成和发展的关键问题。这些望远镜带来了许多技术挑战，这些系统成功的关键是使用了自适应反射镜组件，可以补偿由于风振和重力引起的扭曲造成的大气变化以及望远镜光学系统形状和对准的变化。所提出的ELTS设计都包括一个大的自适应反射镜，系统的尺寸为2-4米。这种大小的自适应反射镜很难制造，因为它需要非常薄才能快速变形。传统上，玻璃被用作镜子的底座，但这么大、这么薄的镜子很难制造，而且有很高的骨折风险。这项拟议的研究将开发一种替代玻璃的材料，即镀镍碳纤维复合材料，这种材料有可能生产出更轻、更低成本的低破裂风险镜子。

The largest optical telescopes that are in use in the world today have primary mirrors of up to 10 meters in diameter. The size of the primary mirror essentially determines how faint an object the telescope can detect. Work is currently under way on the development of the next generation of telescopes. These will have primary mirror diameters of 30-60 meters in size and are generally termed extremely large telescopes (ELTs). A 30 meter telescope will be able to detect and study an object ~9 times fainter than a 10 meter telescope and hence will be able to look back further back into early universe and answer some key questions about how galaxies formed and developed. These telescopes pose many technical challenges and key to the success of these systems is the use of adaptive mirror components that can compensate for the atmospheric variations and changes in the shape and alignment of the telescope optics due to the effect of wind-shake and gravitational induced distortions. The proposed designs for the ELTs all include a large adaptive mirror in the sytems of 2-4 meters in size. This size of adaptive mirror is difficult to make as it needs to be very thin in order to be rapidly deformed. Traditionally glass is used as the basis of a mirror but such large thin mirrors are difficult to make and pose a high risk of fracture. The research proposed will develop an alternative material to glass, namely nickel coated carbon fibre composite, that has the potential of producing a low fracture risk mirror that is lighter and lower cost to produce.