Novel Mathematical Techniques for Advanced Tool-paths to Transform High-value Optical Fabrication

用于先进刀具路径的新颖数学技术，以改变高价值光学制造

• 批准号: ST/L001950/2
• 负责人: David Walker
• 金额: $ 6.31万
• 依托单位: University of Huddersfield
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FL001950%2F2
• 关键词: Novel; Mathematical; Techniques; Advanced; Tool

Precision lenses and mirrors are used for a host of applications - ground-based telescopes for astronomy, satellites looking up at space or down at the ground, machines to make semiconductor 'chips' (for computers to mobile phones...), defence systems, laser-systems and numerous other applications.The manufacture of precision optics is basically a two-stage process. First a glass blank is ground with a hard grinding wheel that cuts the material, to hog out the glass to the basic curved form. The glass is then polished using some form of pad that rubs the surface, using a water-slurry of a polishing compound - red rouge in the old days, white cerium oxide powder today. Over the last decade, the optics industry has experienced a revolution in computer numerical control (CNC) of both the grinding and polishing processes. The project involves two partner companies pre-eminent in both types of machine and processes. Zeeko Ltd (originally spun out of UCL research in this field) manufactures CNC polishing machines and measurement equipment. Cranfield Precision Ltd (a division of Cinetic Landis) produces CNC grinding machines. Such CNC machines almost always move the grinding or polishing tool across the surface in a standard back-and-forth raster pattern, or in a spiral path (by rotating the work-piece). A raster or spiral is a special case, because it crosses itself nowhere, and this simplifies calculating how the removal adds up. But, just like a tractor ploughing a field, these paths leave regular 'furrows' in the surface. Whilst these might be only nanometres deep (just tens of atoms) they cause stray light around an image in a telescope or camera. There are various ways of smoothing surfaces to remove these regular features, but this takes additional times. Moreover, each extra process leaves its own signature, which itself has to be removed ... in what sometimes seems like an endless circle!The new research will break out of this mould by using advanced mathematical methods to generate more complex tool-paths, which cross each other at myriads of points, and give a natural averaging effect. We call these 'hyper-crossing paths'. Furthermore, the polishing machines are able to change the polishing spot size 'on the fly'. In principle (and with the right mathematics) spot-size could be actively tuned to attack different sizes of surface-feature as the tool moves across a surface. We plan to develop this new idea, and are confident it will lead to a break-through in superior surfaces in less time.And what of the results? These will be incorporated in the standard software of the partner companies, enhancing their competitive position. The results will also be used on the machines at the National Facility for Ultra-precision Surfaces in North Wales, operated by Glyndwr University in partnership with University College London. This will give enhanced capability for manufacturing optics to support British Science and our overseas collaborators. Beyond this we plan to disseminate the findings to the wider UK academic and and manufacturing communities to collaborate on and develop applications and prototypes for applications in high precision surfaces outside of the optics sector e.g. medical - prosthetic joints.

精密镜头和反射镜用于多种应用 - 用于天文学的地面望远镜、仰视太空或俯视地面的卫星、制造半导体“芯片”的机器（用于计算机到移动电话......）、国防系统、激光系统和许多其他应用。精密光学器件的制造基本上是一个两阶段过程。首先，用硬砂轮研磨玻璃毛坯，切割材料，将玻璃磨成基本的弯曲形状。然后使用某种形式的垫子摩擦表面，使用抛光剂的水浆对玻璃进行抛光——过去是红色胭脂，现在是白色氧化铈粉末。在过去的十年中，光学行业经历了研磨和抛光工艺的计算机数控 (CNC) 革命。该项目涉及两家在机器类型和工艺方面均表现出色的合作伙伴公司。 Zeeko Ltd（最初是从伦敦大学学院在该领域的研究中分离出来的）制造数控抛光机和测量设备。 Cranfield Precision Ltd（Cinetic Landis 的子公司）生产数控磨床。此类数控机床几乎总是以标准的来回光栅图案或螺旋路径（通过旋转工件）在表面上移动研磨或抛光工具。栅格或螺旋线是一种特殊情况，因为它不会与自身相交，这简化了移除累加的计算。但是，就像拖拉机耕田一样，这些路径会在地表留下规则的“犁沟”。虽然这些可能只有纳米深（只有数十个原子），但它们会在望远镜或相机中的图像周围产生杂散光。有多种方法可以平滑表面以去除这些规则特征，但这需要额外的时间。此外，每个额外的过程都会留下自己的签名，而这些签名本身必须被删除......有时看起来像是一个无尽的循环！新的研究将打破这种模式，使用先进的数学方法来生成更复杂的刀具路径，这些路径在无数的点上相互交叉，并给出自然的平均效果。我们称这些为“超交叉路径”。此外，抛光机能够“即时”改变抛光点尺寸。原则上（并且通过正确的数学计算），当工具在表面上移动时，可以主动调整光斑尺寸以攻击不同尺寸的表面特征。我们计划开发这一新想法，并有信心它将在更短的时间内实现卓越表面的突破。结果如何？这些将被纳入合作伙伴公司的标准软件中，从而增强他们的竞争地位。研究结果还将用于北威尔士国家超精密表面设施的机器上，该设施由格林多尔大学与伦敦大学学院合作运营。这将增强光学制造能力，以支持英国科学和我们的海外合作者。除此之外，我们计划将研究结果传播给更广泛的英国学术界和制造界，以合作开发光学领域以外高精度表面的应用程序和原型，例如光学领域。医疗-假肢关节。

项目成果

Mid-spatial frequency removal on aluminum free-form mirror.

• DOI: 10.1364/oe.27.024885
• 发表时间: 2019-09
• 期刊: Optics express
• 影响因子: 3.8
• 作者: Hongyu Li;D. Walker;Xiao Zheng;Xing Su;Lunzhe Wu;Christina Reynolds;Guoyu Yu;Tony Li;Peng Zhang

Closing the metrology/process loop in CNC polishing

CNC 抛光中的计量/工艺闭环

• DOI: 10.1117/12.223553
• 发表时间: 2016
• 作者: Walker D.D.

Robotic automation in computer controlled polishing

• DOI: 10.2971/jeos.2016.16005
• 发表时间: 2016-01-01
• 期刊: JOURNAL OF THE EUROPEAN OPTICAL SOCIETY-RAPID PUBLICATIONS
• 影响因子: 1.5
• 作者: Walker, D. D.;Yu, G.;Zhang, P.
• 通讯作者: Zhang, P.

Process Automation in Computer Controlled Polishing

计算机控制抛光的过程自动化

• DOI: 10.4028/www.scientific.net/amr.1136.684
• 发表时间: 2016
• 期刊: Advanced Materials Research
• 作者: Walker D

Insight into aspheric misfit with hard tools: mapping the island of low mid-spatial frequencies

用硬工具洞察非球面失配：绘制低中空间频率岛

• DOI: 10.1364/ao.56.009925
• 发表时间: 2017
• 期刊: Applied Optics
• 影响因子: 1.9
• 作者: Walker D