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The authors present a simple and efficient technique for laser writing of arbitrary nanopatterns across a large surface area without using projection masks. It is based on the unique near-field focusing effect of a self-assembled particle array on the surface interacting with an angular incident laser beam. The spot resolution can be down to 80 nm. More than 6 ϫ 10 6 nanolines and c-shaped uniform patterns were fabricated simultaneously over an area of 5 ϫ 5 mm 2 by a few laser shots.

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This paper reports the formation of uniform single layer micro-patterns of graphene on a glass substrate using direct femtosecond laser cutting. The cutting of graphene was achieved in air and argon. By translating the graphene sample with respect to the laser beam, continuous micro-channels were carved. The cutting geometry can be controlled by varying the laser fluence and the scanning path. Also, 1∼2 μm wide graphene micro-ribbons were hatched out. The ablation threshold of graphene was determined to be 0.16∼0.21 J/cm 2 . With the laser fluence higher than the ablation threshold, graphene was ablated rapidly and removed completely without damaging the glass substrate. Atomic force microscopy (AFM) and Raman spectroscopy have been used to confirm the ablation of graphene. Time domain finite difference modelling was employed to understand the thermal history of the laser ablation process.

. (2014) The effects of short pulse laser surface cleaning on porosity formation and reduction in laser welding of aluminium alloy for automotive component manufacture. Optics and Laser Technology, 64 . pp. 162 171. ISSN 0030 3992 It is advisable to refer to the publisher's version if you intend to cite from the work. This paper reports the effects of short pulsed laser surface cleaning on the porosity formation in laser welding of AC-170PX (AA6014) aluminium sheets (coated with Ti/Zr and lubricated using a dry lubricant AlO70) with two types of joints: fillet edge and flange couch, using an AA4043 filler wire for automotive component assembly. The effect of laser cleaning on porosity reduction during laser welding using a filler wire has not been reported before. In this work, porosity and weld fusion zone geometry were examined prior to and after laser cleaning.The nanosecond pulsed Nd:YAG laser cleaning was found to reduce porosity significantly in the weld fusion zones. For the fillet edge welds, porosity was reduced to less than 0.5% compared with 10-80% without laser cleaning. For flange couch welds, porosity was reduced to 0.23 -0.8% from 0.7 -4.3% without laser cleaning. This has been found to be due to the elimination of contaminations and oxide layers that contribute to the porosity formation. The laser cleaning is based on thermal ablation.2