WEB Fabrication and hydration assessment of diffraction gratings in ophthalmic polymers by Direct Laser Interference PatterningWednesday (23.09.2020) 10:40 - 10:55 F: Functional Materials, Surfaces, and Devices 2 Part of:
The fabrication of diffractive elements in ophthalmic polymers to induce refractive index changes to be applied for refractive correction is of great interest in the fields of optics and ophthalmology. In this work, poly-hydroxyethyl-methacrylate (PHEMA) and silicone hydrogel polymers used as soft contact lenses were structured with linear periodic patterns by means of Direct Laser Interference Patterning (DLIP). As laser sources, a Q-switched laser system emitting 10 ns pulses at a wavelength of 266 nm and a mode-locked solid-state oscillator delivering 12 ps laser pulses at a wavelength of 532 nm were used to produce periodic patterns on the surface of the polymer material. DLIP structuring was carried out employing a two-beam interference setup, studying the features of the laser processed areas as a function of both the laser fluence and the interference spatial period. Optical confocal microscopy and micro-Raman spectroscopy were used to evaluate the topography and the microstructural changes induced in the processed samples. Also, diffraction assessment was carried out under illumination of a continuous-wave 632.8 nm He-Ne laser in the DLIP processed areas to determine the refractive index change variation achieved in the structured areas. Finally, static water contact angle (WCA) measurements were carried out with deionized water droplets on the structured areas to evaluate the hydration properties of DLIP structures.