4.11. Fabrication of functional surfaces using ultrashort laser pulse ablation

Public examination of a doctoral dissertation in the field of physics

Doctoral candidate: M.Sc. Jarno Kaakkunen  

Date and venue: 4.11.2011 at 12 noon, M100, Metria, Joensuu campus 

 ABSTRACT 

This thesis considers ultrashort laser ablation of functional surfaces using diffractive optics. Three different functionalities are studied: optical absorption, wetting and diffraction. Various fast diffractive optics based exposure systems are demonstrated, applying ultrashort laser pulse ablation, to realize these functionalities. Among the benefits of ultrashort pulses is the fact that they are suitable for direct processing of various materials. 

First, a surface with high optical absorption is realized by interfering four ultrashort pulses using an optical setup based on two lenses and a grating. Then a water repellant plastic surface is demonstrated by applying a diffractive optical element (DOE) together with ultrashort laser processing. Here the plastic is not directly laser processed to become super-hydrophobic, but ultrashort laser pulses are used to fabricate a mould for mass-production processes such as injection moulding. Finally, ultrashort pulses are used with a system composed of two gratings to process two dimensional (2D) diffractive structures with feature sizes less than one micron. 

The doctoral dissertation of M.Sc. Jarno Kaakkunen  entitled Fabrication of functional surfaces using ultrashort laser pulse ablation will be examined at the Faculty of Science and Forestry.The opponent in the public examination is Professor Olivier Parriaux, Universit√© Jean Monnet and the custos is Professor Pasi Vahimaa of the University of Eastern Finland.  

Photo available for download at http://www.uef.fi/vaitoskuvat

Contact: Jarno Kaakkunen, jarno.kaakkunen@uef.fi,  tel. +358 40 776 6158

Publishing year: 2011

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