Acta Medica Okayama 00078506 68 1 2019 High surface quality micro machining of monocrystalline diamond by picosecond pulsed laser 197 200 EN Y. Okamoto Graduate School of Natural Science & Technology, Okayama University A. Okada Graduate School of Natural Science & Technology, Okayama University A. Kajitani Graduate School of Natural Science & Technology, Okayama University T. Shinonaga Graduate School of Natural Science & Technology, Okayama University In micro machining of monocrystalline diamond by pulsed laser, unique processing characteristics appeared only under a few ten picosecond pulse duration and a certain overlap rate of laser shot. Cracks mostly propagate in parallel direction to top surface of workpiece, although the laser beam axis is perpendicular to the surface. This processed area can keep diamond structure, and its surface roughness is smaller than R-a = 0.2 mu M. New laser micro machining method to keep diamond structure and small surface roughness is proposed. This method can contribute to reduce the polishing process in micro machining of diamond. (C) 2019 Published by Elsevier Ltd on behalf of CIRP. No potential conflict of interest relevant to this article was reported.