An automated micro-grinding system for the fabrication of precision micro-scale profiles

Production of micro-scale components is an important emergent field. One underdeveloped area is the production of micro-scale 3D surfaces, which has important applications in micro-optics and fibre optic sensors. One particular application is the production of micro-lenses. With scales of less than 200 μm these lenses can improve light coupling efficiencies in micro-optic systems. However, current lens production techniques have limitations in accuracy and versatility. Creating these surfaces through mechanical micro-grinding has the potential to improve the precision and variety of profiles that can be produced, thus improving transmission efficiencies and leading to new applications.This work presents a novel micro-grinding method for the production of microscale asymmetric, symmetric and axisymmetric curved components from brittle materialssuch as glasses. A specialised micro-grinding machine and machining systemhas been designed, constructed and successfully tested and is presented here. Thissystem is capable of producing complex profiles directly on the tips of optical fibreworkpieces. A five degree of freedom centring system is presented that can align androtate these workpieces about a precision axis, enabling axisymmetric grinding. Amachine vision system, utilising a microscope lens system and sub-pixel localisationtechniques, is used to provide feedback for the process, image processing techniquesare presented which are shown to have a sensing resolution of 300 nm. Using thesesystems, workpieces are centred to within 500 nm. Tools are mounted on nanometreprecise motion stages and motion and infeed are controlled. Tooling configurationswith flat and tangential grinding surfaces are presented along with control and pathgeneration algorithms. The capabilities and shortcomings of each are presentedalong with methods to predict appropriate feed rates based on experimental data.Both asymmetric and axisymmetric flat and curved micro-profiles have beenproduced on the tips of optical fibres using this system. These are presented andanalysed and show that the system, as described, is capable of producing high qualitymicro-scale components with submicron dimensional accuracy and nanometricsurface quality. The advantages of this technique are compared with other processesand discussed. Further development of the system and technique are also considered