Experimental Setup

We use single nanosecond pulses of an injection seeded Nd:YAG laser at the wavelengths 1064nm, 532nm or 266nm to generate an interference pattern. For that purpose the beam is split into several beams by beam splitters. These individual beams are then directed towards the surface to be structured by the help of mirrors. There an interference pattern is formed, which depends on the number of beams, their wavelength, polarization and the angles between the beams. 

Optical microscopy of 2- and 3-beam interference pattern

Surface appearance after illumination at low intensities

Above a material dependent energy threshold a permanent surface structure can be observed. We show here some examples of patterned surfaces.

Au 50nm thickness

Especially on thin films structures appear which are on a first look difficult to explain. The feature height of the metallic hillocks can be larger than the film thickness.