Surface modification of anodised aluminium using a femtosecond laser

Femtosecond laser pulses at 775 nm, combined with a scanning galvonometer system, have allowed the micro scale structuring of an aluminium plate coated with a 2 micron thick anodised aluminium layer for potential industrial applications. The micro-scale structuring of aluminium was investigated using ultrafast pulses of 180 fs duration at a repetition rate of 1 kHz. Under suitably optimised conditions, the interaction of the laser pulses with the substrate created a hydrophilic surface with a contact angle of less than 10 degrees. These surfaces revealed a 'lotus-leaf' like morphology when examined under a Scanning Electron Microscope (SEM). It has been found that these laser processed hydrophilic surfaces revert with time and they undergo this cycle of alternate hydrophilic/hydrophobic behaviour several times upon exposure to the laser pulses. Their potential application in the printing industries is strong due to their reusability and sustainability; initial trials on printing confirm this. This technology would offer extra advantages as a non-chemical process without the need for developer, thereby reducing the overall cost and time of printing.