Casting and Polishing 8M Telescope Mirrors

该奖项支持8米望远镜镜面铸造和抛光技术的发展。在这种尺寸下，考虑到刚度、重量和热响应，蜂窝夹层设计对镜坯是非常有利的。在过去的几年里，亚利桑那大学开发了一种铸造技术，将玻璃熔化成复杂的模具，形成蜂窝夹层结构。已经铸造了两个350万的空白。在筹资期内，将扩大铸造炉，并生产首批6.5米和8米尺寸的铸件。该项目还涉及镜面抛光的应力搭接方法的开发。这是对以合理的速度抛光高度非球面的问题的直接和直接的攻击。当它穿过镜子时，它的形状会改变，以匹配它下面表面的不同形状。这种方法对最大的望远镜尤其重要，如果初级望远镜焦距较短，那么这种望远镜在稳定性和经济性方面都有好处，因此具有很强的非平稳性。抛光速度对于非常大的表面的经济生产也是至关重要的。这两项正在开发的技术预计都将应用于大型光学领域，而不仅仅是天文学。

This award supports the development of technology for casting and polishing 8m telescope mirrors. At this size, considerations of stiffness, weight and thermal response strongly favor honeycomb sandwich design for the mirror blank. Over the past few years a casting technique has been developed at the University of Arizona in which glass is melted into a complex mold to form a honeycomb sandwich structure in one piece. Two 3.5m blanks have already been cast. In the funding period the casting furnace will be enlarged, and the first castings made at the 6.5m and 8m size. The project is also concerned with the development of the stressed lap method of mirror polishing. This is a straightforward and direct attack on the problem of polishing highly aspheric surfaces with reasonable speed. The lap's shape is changed as it moves across the mirror, to match the varying shape of the surface under it. The method is important especially for the largest telescopes, which benefit in stability and economy if the primary has a short focal length, and is thus strongly asperic. Speed of polishing is also critical for economical production of very large surfaces. Both the technologies being developed can be expected to find application to large optics in general, not just in astronomy.