Abstract. The effect of double nanosecond laser pulses on the titanium surface and the changes in the morphology of ablative catheters caused by them are studied. The considered mode of dual nanosecond pulses allows more efficient use of laser energy for the problems of microrelief formation in comparison with the mode of mono-pulse action due to the separation of the "excess" power density by the time delay exceeding the lifetime of the laser plasma. It is shown that the variation of the time parameters of the double pulses leads to an increase in the depth of the removed layer by about 1.5 times, a twofold increase in the aspect ratio, as well as a decrease in the amount of the liquid phase of the material emitted by the recoil pressure. A complex two-level microstructure of craters is found to be formed in the mode of dual nanosecond pulses. The obtained crater structures in the mode of double nanosecond pulses can be used to change the tribological properties of the metal surface and to create functional micro-reliefs.

Keywords: laser ablation, double nanosecond pulses, ablation crater, micro-structuring, functional microrelief, ytterbium fiber laser

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