Transferring Technology in Optimised Metal-Mirror Fabrication

这项研究的主要目的是向英国工业界转让制造金属镜子的先进技术--既有哈德斯菲尔德大学拥有丰富经验的现有方法，也有在项目期间开发的改进方法。用金属制造镜子的想法可以追溯到艾萨克·牛顿爵士的反射望远镜，他于1668年建造了这座望远镜，以克服当时简单的玻璃透镜的彩色条纹问题。他选择的合金--窥镜--很硬，很容易抛光，但很快就失去光泽，而且有效反射光线的能力，按现代标准来看并不好。铝合金已经取代了窥镜，因为铝的可用性在大尺寸的低成本，因为它的上级反射性能和耐用性。虽然随着温度的变化，它的膨胀和收缩比玻璃大得多，但它的稳定速度要快得多，因为它的导热性很好。而且，你可以把它掉下来，或者摇晃它，它也不会坏！然而，铝有一个明显的缺点-它是软的，难以抛光。出于这个原因，铝镜通常通过使用非常高精度的车床和金刚石工具车削而制成中等尺寸。不幸的是，金刚石车削不可避免地会在表面留下特征，这使得镜子在“可见”光下成像效果不佳。相反，它们通常用于更宽容的红外线（例如夜视镜）。在米尺寸，铝镜通常被传统加工，然后镀镍，因为这更容易抛光。但是镍的反射性能不如铝，所以回到第一步！更糟糕的是，镍的膨胀与铝不同，整个镜子会随着温度的变化而变形。第一种方法是使用计算机控制的抛光机和机器人平台去除金刚石镜面上的特征。金刚石车削将使用校园内的机器进行，由合作伙伴CFT有限公司提供专用金刚石工具。然后，抛光将在哈德斯菲尔德位于STFC达雷斯伯里的新实验室进行，使用合作伙伴公司Kemet有限公司提供的高度专业化的磨料浆。开发的技术将转移到一家制造光学器件的国防公司，QioptiQ有限公司。第二条途径是根据合作伙伴Kemet有限公司的需要，开发制造米级裸铝镜的方法。然后，通过转让技术并升级其研磨和抛光设备，将Kemet定位为潜在供应商。在这两种情况下，以前的研究中缺少的一个关键方面是调查过程步骤之间的详细相互作用。就误差的高度而言，最好的表面可能不适合抛光，因为这些误差如何分布在表面上。我们相信，该项目将在考虑上述两种途径的这种方法方面开辟新的天地。

The main objective of the proposed research is to transfer to British Industry advanced technologies in making metal mirrors - both existing methods in which the University of Huddersfield has considerable experience, and improvements to be developed during the project.The idea of making mirrors out of metal goes right back to Sir Isaac Newton's reflecting telescope, which he built in 1668 as a way to overcome the colour fringe problem with the simple glass lenses available at that time. His chosen alloy - speculum - was hard and easy to polish, but tarnished quickly, and the ability to reflect light effectively, was not good by modern standards. Aluminium alloys have superseded Speculum, due to aluminium's availability at low cost in large sizes, and because of its superior reflection properties and durability. Whilst it expands and contracts much more than glass with changing temperature, it settles down much more quickly because it conducts heat very well. Moreover, you can drop it or shake it and it will not break!However, aluminium has a distinct disadvantage - it is soft and difficult to polish. For this reason, aluminium mirrors have normally been made in modest sizes by turning using a very high-precision lathe and diamond tools. Unfortunately, diamond-turning inevitably leaves characteristic features on surfaces, which make the mirrors not very good for imaging in 'visible' light. Instead, they are usually used in the more-tolerant infrared (e.g. for night-vision goggles).In metre sizes, aluminium mirrors have normally been machined traditionally, then nickel-plated, as this is easier to polish. But nickel has inferior reflection properties to aluminium, so back to square-1! Worse, the nickel expands differently from aluminium, and the whole mirror can distort with temperature changes.With that background, the project concerns two main avenues of investigation. The first tackles removing the features on diamond-turned mirrors, using computer-controlled polishing machines and robot platforms. The diamond turning will be performed using machines on-campus, with specialised diamond tools provided by the partner CFT Ltd. Then, polishing will proceed in Huddersfield's new laboratory at the STFC-Daresbury site, using highly specialised abrasive slurries from the partner company Kemet Ltd. The technology developed will be transferred to a defence company making optics, QioptiQ Ltd.The second avenue is to develop methods to make bare aluminium mirrors in metre sizes, as needed by partner TMF Ltd. The idea is then to position Kemet as a potential supplier, by transferring technology and so upgrading their lapping and polishing facility.In both cases, a key aspect missing from previous research is investigating the detailed interactions between process steps. The best surface in terms of the heights of errors, may not be best for polishing, because of how those errors are distributed over the surface. We believe the project will break new ground in considering this type of approach for both avenues above.