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Featured Application: The presented study proposes technology for increasing stealth and preventing the unmasking of objects, including orbital ones, by forming a complex two-period surface microstructure using femtosecond laser processing. Currently, the technology of imparting the necessary reflective properties to a surface is becoming increasingly important. Darkening the surface and matting it helps to diffuse the reflected beam and prevent glare. The surface's reflective properties are determined by its microstructure. Modern pico- and femtosecond lasers make it possible to obtain surfaces with high precision and create various LIPSS (laser-induced periodic surface structure) types. In this article, we describe the process of formation of a complex two-periodic microstructure on the surface of AISI 321 stainless steel under the influence of radiation from femtosecond lasers and describe the process of scattering of a light beam by the resulting surface. Modeling shows that the presence of an additional transparent coating on a flat surface does not improve its scattering properties and does not eliminate glare. In the event that a complex two-periodic structure is formed on the reflective surface and the coating surface, the nature of the reflection has a clearly defined scattered character, regardless of the angle of incidence of the light beam. This study shows the feasibility and effectiveness of forming a two-periodic structure in order to give it stealth characteristics and reduce visibility. [ABSTRACT FROM AUTHOR]

The dependency of CO2 reduction rate in acetonitrile-Bu4NClO4 solution on cathodes, which were modified by laser induction of a copper surface, was studied. The topography of laser-induced periodic surface structures (LIPSS) → grooves → spikes was successively formed by a certain number of pulses. It was proved that for a higher number of laser pulses, the surface area of the copper cathode increases and preferred platy orientation of the copper surface on [022] crystallografic direction and larger fluence values increase. At the same time, the content of copper (I) oxide on the surface of the copper cathode increases. Also, the tendency to larger fluency values is observed. It promotes the increase of cathodic current density for CO2 reduction, which reaches values of 14 mA cm-2 for samples with spikes surface structures at E = − 3.0 V upon a stable process. [ABSTRACT FROM AUTHOR]

In this paper, we report about formation of laser-induced periodic surface structure LIPSS on amorphous Fe-based alloy. The HR-LIPSS was obtained using the femtosecond (266 fs) pulse laser irradiation with a wavelength of 1035 nm. SEM and AFM, as well as optical microscopic examinations with a digital camera, were used for surface topology investigation and LIPSS studies. Images obtained by SEM were analyzed using the DLOA method (Dispersion of LIPSS Orientation Angle) and HR (highly regular) LIPSS was identified. The DLOA of HR-LIPSS was measured as 7.5°. Parameters of laser irradiation were estimated for HR-LIPSS producing on the amorphous metallic ribbon. Amorphous ribbon structure after LIPSS formation was studied using the back-scattered X-ray diffraction method. No crystalline phases were detected on the ribbon surface after LIPSS forming on it; so, the ribbon kept an amorphous structure. [ABSTRACT FROM AUTHOR]