| Abstract [eng] |
Laser induced periodic surface structures (LIPSS) have a multitude of applications. From solar energy industry to LED manufacturing, control of wetting properties of a material and much more. To carry out the experiment Yb:KGW laser was used (1035 nm wavelength, 177 fs pulse length, the parameters used to generate different surface morphologies are summarized in Lentelė 2). The goal of this work was to determine the principles of the formation of periodic structures, formed by high-frequency femtosecond laser pulses on the surfaces of sapphire and calcium fluoride. To inscribe, by changing the number of pulses, various periodic structures on the surfaces and investigate the morphology and periodicity of those structures. Based on the results of the experiment, the conclusions are as follows:  After exposure to pulses from high frequency femtosecond laser, periodic structures are formed on the surfaces of sapphire and calcium fluoride. The morphologies of those surfaces depend on the number of pulses used.  Increase of the number of pulses used leads to the change of the surface morphologies from HSFL (Al2O3 – 366±21 nm, CaF2 – 374±28 nm) to LSFL (Al2O3 – 807±118 nm, CaF2 – 1768±116 nm, in the case of Al2O3 surface morphology is aperiodic), and finally to LIPASS (Al2O3 – 787±46 nm, CaF2 – 1029±9 nm). Similar LIPASS form on both samples despite the differences of material properties.  Despite the different mechanical, optical and thermal properties of sapphire and calcium fluoride, the observed morphology evolutions of both surfaces are similar. It is possible that this is the case because the principles of formation of periodic structures are similar and the morphology dependance on the number of pulses used is universal. |
