Optical Properties of Sol-Gel Coatings on Plastic Foils Embossed with Surface-Relief Gratings

A novel technique has been developed to fabricate surface-relief gratings using sol-gel derived porous coating on plastic foil substrates. Organically modified TiO₂ sol was prepared by roll-coating on OPP foil substrates. The plastic films coated with TiO₂ nano-particles were embossed to form surface-relief gratings with micro-structures. The morphology of the porous coatings and the micro-structures were investigated using electron scanning microscopy (SEM). Optical transmission of the films was measured using UV-VIS and IR spectroscopy. The diffraction efficiency of the gratings on the coated plastic foil was examined in terms of fabrication conditions. It was shown that special figures could be seen in the films when the angle of view was changed. The final products of the composite films are transparent and suitable for industry manufacture and applications.