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On the theoretical foundation for the microcutting of calcium fluoride single crystals at elevated temperatures

MetadataDetails
Publication Date2016-08-29
JournalProceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture
AuthorsHao Wang, Annamalai Senthil Kumar, Oltmann Riemer
InstitutionsNational University of Singapore, University of Bremen
Citations14

The machining of a CaF 2 lens with the near-perfect crystal structure poses a more challenging task than simply performing a ductile-regime cutting on brittle materials to achieve an optical surface finish without microcracks in the subsurface layer. This research advances the understanding of the ductile-brittle transition mechanism through material characterisation. The convincing evidence for the advantage of ultraprecision diamond turning over the optical polishing process is disclosed in the comparative experimental tests. A promising solution of thermally enhanced microcutting is proposed to meet both the ubiquitous and ad hoc requirements for the fabrication of the CaF 2 lens. The theoretical foundation for the CaF 2 microcutting at elevated temperatures is for the first time established based on a semi-quantitative modelling and simulation with the crystal plasticity finite element method.