Ultra-precision machining of optoelectronics and microsystems (UPROAR)

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Our overall goal is to develop an ultraprecision dicing / grinding system that will be applicable to photonics and microsystems. Working with a set of UK companies we will develop the system as a test-bed and implement a set of cutting edge instrumentation add-ons to better control the machining of materials with sub-nanometre surface finishes and sub-100 nanometre overall tolerancing on complex objects.Dicing relies on a diamond-impregnated cutting disc driven at up to 150,000 rpm on a spindle being accurately translated relative to a workpiece. Any vibration or lack of perfection in the system will result in degraded surfaces, chipping of diced facets and edge chipping on grooves and channels. Importantly when placing the dicing blade on the spindle, there are inevitable errors in truism, for example, whether the blade is accurately at 90 degrees to the spindle axis, whether the blade is perfectly concentric, and whether the translation is truly along the direction of the blade. Of course, in the real world, these things are never truly perfect, and so a goal of the project is to implement feedback and control, which allows adaptive compensation. In the project, we will build a system using 900kg of granite to hold and create an ultra-stiff system, then use air-bearing elements and control signals to identify and create feedback loops to achieve incredible levels of surface finish and overall precision. Critically we will work in the ductile machining regime where operation in the elastic limit of the material allows us to avoid brittle fracture and the sort of damage which majorly degrades the performance of optical and microsystem elements.We will be looking at a range of optical and electronic materials, including glasses, crystals and semiconductors. In the latter phase of the project, we will be looking to adopt and create new ways to 'true' the blade, using state-of-the-art metrology to control issues of blade side-wall wear, blade flutter, non-concentricity originated machining rates and load-related vibration. From this work, we expect to gain valuable insights that will help our commercial partners. Firstly, by creating new ultra-precision machine tools in the UK, secondly understanding how best to implement advanced techniques and thirdly, by making exemplar devices in technologically important materials to really prove our approaches work.