Fabrication of dynamic holograms on polymer surface by direct laser writing for high-security anti-counterfeit applications

Abstract

Anti-counterfeit technology has attracted much attention with the development of economy, because many counterfeit products that are difficult for identification have been produced, which extremely damage the interests of consumers. Here, a high-resolution ultraviolet direct laser writer is applied to fabricate computer-generated holograms (CGH) with laser spot size of 300 nm for anti-counterfeit applications. The characteristics of the reconstructed images illuminated by monochromatic light are demonstrated in details. Additionally, colorful reconstructed images are observed with white light illumination in the high-security holograms samples. Furthermore, a kinematic effect of colorful reconstructed images are also observed by modifying focus depth and object size in the algorithm. The normal first (+1st) order diffraction and negative first (-1st) order diffraction in the high-security holograms exhibit different sizes due to distinguishing magnifications. The kinematic effect of white-light holograms shows great potential in anti-counterfeit applications due to its simplicity for recognition and high security since they are hard to duplicate.