a – Department of Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GH, UK
b – Institute For Manufacturing, Department of Engineering, University of Cambridge, Mill Lane, Cambridge CB2 11RX, UK
Al2O3 ceramic has been micro-structured in air using 180 fs, l = 775 nm optical pulses in a fluence range 1.4 < F < 21 J cm2 with observed ablation rates of 25 < V < 900 mm3/pulse. The threshold fluence was Fth = 1.1 J cm2 at this ultrashort pulse-length in the NIR. Melting could be minimised using ultrafast optical pulses, improving the edge quality. By optimising the processing parameters, the residual surface roughness could be reduced below the pristine surface Ra = 0.8 mm. The debris produced consists mainly of single crystal nanoparticles of alumina with diameters from 20 nm to 1 mm with an average diameter of 300 nm. # 2005 Elsevier B.V. All rights reserved.