Laser induced ripples' gratings with angular periodicity for fabrication of diffraction holograms

Laser induced ripples (also known as Laser Induced Periodic Surface Structures, LIPSS) have gained a considerable attention by both researchers and industry due to their surface functionalization applications. These ripples act as diffraction gratings for the visible light therefore it is widely used in some optical applications and color marking. In this research, a method is proposed for producing holograms by varying the ripples' orientation along the beam path during the laser scanning and thus producing a pattern of ripples orientations. It was demonstrated that, by employing this method, it was possible to produce linear and radial pattern of gratings by changing the ripples' orientations following a given periodic function. As a result, smooth transitions of diffracted monochromatic light along the beam path were achieved, especially in diffracting colors from different locations when changing the azimuthal and incident angles of the incident white light. In addition, the reflection of polarized white light by such periodic gratings was investigated and it was shown that it was fully dependent on the ripples' orientations in respect to the light linear polarization vector. (C) 2018 Elsevier B.V. All rights reserved.